October CONTINUOUS 2012 VERSUS BATCH PROCESSING

PAGE 34 www.che.com

Process Vacuum Systems

Dry Solids Mixing

Facts at your Fingertips: Fans and Blowers

Steam Systems

Focus on Gas Detection

Ethylene from Shale Gas

PAGE 26 action loves reaction

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Circle 5 on p. 60 or go to adlinks.che.com/40272-05 Now save time, money and space with BULK-OUT™multi-function dischargers Condition, de-lump, screen, feed, weigh batch, combine with liquids, and convey as you discharge, with a custom-integrated, performance-guaranteed discharger system from Flexicon

Dual Bulk Bag Weigh Bulk-Bag-To-Bin Weigh Continuous Loss-of-Weight Bulk Bag Unloader for Sanitary Bulk Bag Batch Eductor conditions, Batching System discharges, Bulk Bag Unloader allows Pneumatic Conveyors has Discharger with patented discharges by weight, and de-lumps and feeds material continuous gravimetric surge hopper with rotary USDA-accepted flow control blends into a liquid stream gravimetrically discharging airlock feeder for metering valve cleans rapidly

Bulk Bag Unloader for Bulk Bag Conditioner- Half Frame Unloaders Combination Bulk Bag Split-Frame allows loading Pneumatic Conveyors has Unloader loosens solidified with Conveyor or Airlock Discharger and Manual of bag frame or rigid bins surge hopper with non-flow- material, then discharges, require forklift, eliminating Dumping Station has multi- onto subframe within 4 in. through pick-up adapter de-lumps and conveys cost of upper frame purpose hopper interface (100 mm) of ceiling

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Circle 20 on p. 60 or go to adlinks.che.com/40272-20 OCTOBER 2012 IN THIS ISSUE VOLUME 119, NO. 10

ONLY ON CHE.COM More on: Shale Gas news; A Web Exclusive article on Environmental Permitting Issues for Dryers and Kilns; New Products; www.che.com Latest news; and more

COVER STORY 26 Cover Story Acids Handling General guidelines on materials, storage, pumping and other concerns for the proper and safe handling of acids

NEWS

11 Chementator A cryogenic turbo mill generates rubber powder from recycled tires; A concept for making gasoline from air; A polymersome that releases its cargo where needed; Progress for making smart membranes; and more

16 Newsbriefs CFATS administration needs improvement, testimony EQUIPMENT & SERVICES DEPARTMENTS argues; Shell to construct world’s first 23 Focus on Gas Detection Measure Letters 6 oil-sands CCS project; ECHA thousands of gases in the field; Fixed gas Calendar ...... 8–9 seeks public consultation; and more detector is protected against dust and water; Who’s Who ...... 62 17 Newsfront Shale Gas Ushers in Detector approved for underground mining; Ethylene Feed Shifts Growth in Carbon dioxide detector protects against Reader Service . . . 60 dangerous leaks; and more ethane cracking has wide effects Economic for the CPI 24D-1 ChemInnovations Show Preview Indicators . . . . 63–64 20 Newsfront A Steamy Situation (Domestic edition) The 3rd annual Many chemical processors do not realize ChemInnovations conference and tradeshow ADVERTISERS the full potential of their steam systems will take place in New Orleans on November 14–15. The show will feature a conference Product Showcase . 56 ENGINEERING program, news on emerging technologies Classified and more. Featured subjects of the Advertising . . . 57–59 25 Facts at Your Fingertips Fans and Chementator Lightning Round, a live, on- Advertiser Index . . 61 Blowers This one-page reference guide stage interview with experts on innovative discusses major considerations in setting technologies, are described up and operating fans and blowers COMING 24I-1New Products (International IN NOVEMBER 34 Feature Report From Batch to edition) Let this company collect and Look for: Feature Re- Continuous Processing Continuous analyze machinery vibration data; Power ports on Dust Safety; flow reactors can provide many benefits supplies with large current outputs; New and Variable Frequency over batch processes. This article features offered in this latest CFD software; Drives for Centrifugal answers why and how This wireless vibration transmitter now Pumps; Engineering has ATEX approval; This oxygen analyzer is 41 Solids Processing Blending, Practice articles on certified for hazardous areas; and more Sampling and Segregation Don’t Anti-surge valve selec- discount these aspects of dry solids tion and sizing; and COMMENTARY mixing, which represent three sides Chemical Injection Sys- of the same coin 5 Editor’s Page Water and energy are tems; a Focus on Ana- lyzers; News articles 47 linked The interdependence between Environmental Manager Reduce water and energy is explored on the Employment Hazards in Process Vacuum Systems Outlook; and Pressure 55 Reduce explosion risks, and chemical The Fractionation Column Measurement and Con- and physical hazards, to ensure safe Who says ChE careers aren’t trol; and more operation of vacuum pumps and adventurous A cautionary tale from the related systems FRI technical director on traveling abroad Cover: David Whitcher

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Circle 14 on p. 60 or go to adlinks.che.com/40272-14 Winner of Eight Jesse H. Neal Awards for Editorial Excellence Editor’s Page

Published since 1902 Water and energy are linked An Access Intelligence Publication PUBLISHER ART & DESIGN his month marks the 40th anniversary of the Clean Water Act (CWA), BRIAN NESSEN DAVID WHITCHER the primary federal law regulating discharges of pollutants into U.S. Group Publisher Art Director/ T [email protected] Editorial Production Manager waters. As far as the developed world’s water priorities go, a great EDITORS [email protected] deal has changed since 1972. For one thing, the top challenge back then REBEKKAH J. MARSHALL PRODUCTION was eliminating releases of toxic substances. Today, that challenge is ar- Editor in Chief guably being met, and we are now getting more serious about minimizing [email protected] STEVE OLSON Director of Production & the consumption of water altogether. DOROTHY LOZOWSKI Manufacturing Managing Editor [email protected] Despite that growing intention, a sometimes-overlooked fact is that [email protected] GERALD ONDREY (Frankfurt) JOHN BLAYLOCK-COOKE water and energy consumption are interdependent. Whether the context Senior Editor Ad Production Manager is the chemical process industries (CPI) or much broader, the truth is this: [email protected] [email protected] The more water that is consumed, the more energy that is needed, and SCOTT JENKINS AUDIENCE Associate Editor vice versa. The connection can be illustrated very clearly by looking at an DEVELOPMENT [email protected] everyday example from the U.S. Environmental Protection Agency (EPA; CONTRIBUTING EDITORS SARAH GARWOOD Audience Marketing Director Washington, D.C.; www.epa.gov). Approximately 4% of electricity demand SUZANNE A. SHELLEY [email protected] in the U.S. is devoted simply to moving and treating drinking water and [email protected] GEORGE SEVERINE wastewater. Conversely, it takes 3,000–6,000 gal/yr of water to power just CHARLES BUTCHER (U.K.) Fulfillment Manager [email protected] [email protected] one 60-W, incandescent light bulb for 12 h/d. PAUL S. GRAD (Australia) JEN FELLING In the CPI, water requires significant energy input for pumping, heat- [email protected] List Sales, Statlistics (203) 778-8700 ing, process uses and treatment (both on the front and back ends). So even TETSUO SATOH (Japan) [email protected] [email protected] if cost savings in water use are not incentive enough on their own, in many JOY LEPREE (New Jersey) EDITORIAL cases reductions in energy use could make up the difference, and some- ADVISORY BOARD [email protected] times more. Meanwhile, shifts in energy and water supplies promise to GERALD PARKINSON JOHN CARSON (California) [email protected] Jenike & Johanson, Inc. increase the stakes moving forward. INFORMATION SERVICES DAVID DICKEY Consider for a moment that emerging energy supplies are not likely to CHARLES SANDS MixTech, Inc. require less water per unit of energy, and in some cases they will require Senior Developer MUKESH DOBLE much more. Take the practice of hydraulic fracturing, for instance, which Web/business Applications Architect IIT Madras, India [email protected] uses vast volumes of water and is increasingly being applied to both oil MARKETING HENRY KISTER and gas exploration. Meanwhile, many emerging biobased routes to both Fluor Corp. JAMIE REESBY energy and chemicals — including those from crops or algae — are based Marketing Director TREVOR KLETZ on mechanisms that need water to grow. Perhaps innovation in these areas TradeFair Group, Inc. Loughborough University, U.K. [email protected] will improve this state of affairs, but it is doubtful that anything would GERHARD KREYSA (retired) JENNIFER BRADY DECHEMA e.V. result in a net decrease in global, or even regional, water demand. Marketing Coordinator TradeFair Group, Inc. RAM RAMACHANDRAN Now think about the fact that as fresh-water resources become more [email protected] (Retired) The Linde Group scarce, the energy required to deliver a gallon of water could itself be on

HEADQUARTERS the rise. If demand increases enough to require that significantly more 88 Pine Street, 5th Floor, New York, NY 10005, U.S. water be sourced through desalination processes, that would in itself mag- Tel: 212-621-4900 Fax: 212-621-4694 nify the energy drain. Desalination is power intensive. EUROPEAN EDITORIAL OFFICES With that in mind, it is time that the CPI start looking at water and Zeilweg 44, D-60439 Frankfurt am Main, Germany Tel: 49-69-9573-8296 Fax: 49-69-5700-2484 energy bills together. In addition to reducing operating costs today, it CIRCULATION REQUESTS: can also get a head start on a brewing problem that is poised to get even Tel: 847-564-9290 Fax: 847-564-9453 more profound. Fullfillment Manager; P.O. Box 3588, Northbrook, IL 60065-3588 email: [email protected] This month’s Equipment News Roundup (p. 20), presents new innovations ADVERTISING REQUESTS: see p. 60 that can achieve big benefits in one of the most obvious connections between For photocopy or reuse requests: 800-772-3350 or [email protected] water and energy efficiency: steam. For reprints: Wright’s Media, 1-877-652-5295, [email protected] Meanwhile, in the CE archives (www.che.com) there is a wealth of prac- ACCESS INTELLIGENCE, LLC tical, how-to guidance on this subject. For instance, the DON PAZOUR ROBERT PACIOREK article Wastewater Treatment: Energy-Conservation Op- Chief Executive Officer Senior Vice President, ED PINEDO Chief Information Officer portunities* presents details on five specific proposals: Executive Vice President SYLVIA SIERRA • Use variable frequency drives (VFDs) to adjust the & Chief Financial Officer Senior Vice President, MACY L. FECTO Corporate Audience Development speed of electric motors to meet process demand Exec. Vice President, MICHAEL KRAUS • Replace old electric motors Human Resources & Administration Vice President, Production and Manufacturing • Maximize the production and use of biogas as a fuel HEATHER FARLEY Divisional President, STEVE BARBER • Switch to a distributed effluent cooling system Access Intelligence Vice President, Financial Planning and Internal Audit • Optimize aeration and oxygen transfer ■ GERALD STASKO Rebekkah Marshall Vice President/Corporate Controller * www.che.com/technical_and_practical/5404.html 4 Choke Cherry Road, Second Floor Rockville, MD 20850 • www.accessintel.com CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 5 Letters

More opinions on ChE education in a biofuels plant? Common practical basics that can and I would like to contribute to the discussion on “practical” should be taught to engineers bound for industry. ChE education (CE, September 2012, p. 5–6). After gradu- I also believe there is no reason why you can’t combine ation, I as well didn’t know what a pipe flange was, nor a engineering theory and practicality in one four-year cur- gasket, didn’t know how to read a pump curve, didn’t know riculum. The amount of math and theory taught in a stan- how to size a relief valve and so on. I could have learned dard ChE program is far too excessive for those going on to more that applies to the CPI [chemical process industries] industry, and there’s no reason why you can’t trim the fat. in an operator training (process technology) curriculum Like you say, eliminate the Laplace Transforms and the that’s offered at the local community college than I ever linear algebra that nobody’s ever going to use. (I did apply a learned in college. The problem as I see it is that the faculty differential equation one time on the job, but that was early of universities are trying to train students to become like on and I still had to go back to the textbook to remember them. But very few actually go on to become teaching pro- how its done.) For example, in the process controls class, fessors since the salaries are better in industry. devote one half of the semester to theory, and one half to a While I agree with Mr. Blanton’s suggestion that intern- practical lab where one can do hands on tuning of control ships are the way to go, opportunities are limited these valves on a DCS simulation of a process plant. days. Those lucky individuals who get an internship repre- I believe it is the responsibility of universities to provide sent a tiny percentage of those who are eligible. The rest of more practical engineering options, and they are doing all us (like myself at the time) end up in manual labor summer of us a disservice by not offering an applied-ChE degree. jobs with no practical experience upon graduation. I remember other articles discussing how it is difficult to I disagree with Mr. Bloss’s assumption that the “engineer- pass the vast knowledge accumulated by retiring engineers ing field is so broad that it is difficult for any university to onto the newly-hired, and a more practical degree would go meet the need of every industry.” Isn’t the ChE curriculum a long way in shortening this gap. In some areas, new engi- itself broad enough supposedly to meet the needs of all neers could essentially “hit the ground running”. chemical engineers? Are you telling me that a centrifugal Jeff Kinsey, process engineer pump used in the plastics industry is different from one used Houston, Tex.

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Circle 3 on p. 60 or go to adlinks.che.com/40272-03 6 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 “Join the ultra-high shear revolution.”

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Circle 18 on p. 60 or go to adlinks.che.com/40272-18 Calendar

NORTH AMERICA (Washington, D.C.). Phone: 202-721-4100; Web: scd-ibio.org 2012 Gasification Technologies Conference. Philadelphia, Pa. November 12–14 Gasification Technologies Council (Arlington, Va.). Phone: 703-276-0110; Web: gasification.org 2012 Aveva World North America User Washington, D.C. October 28–31 Conference. Aveva (Houston). Phone: 832-204-5623; Web: aveva.com 2012 AIChE Annual Meeting. AIChE (New York, N.Y). New Orleans, La. November 12–14 Phone: 203-702-7660; Web: aiche.org Pittsburgh, Pa. October 28–November 2 3rd Annual ChemInnovations Conference & Exhibition, co-located with Clean AFPM International Lubricants & Waxes Meeting. Gulf/Industrial Fire, Safety and Security, and American Fuel & Petrochemical Manufacturers (AFPM; Shale EnviroSafe Conference & Exhibitions. formerly NPRA) (Washington, D.C.). Phone: 202-457-0480; TradeFair Group, an Access Intelligence Co. (Houston). Web: afpm.org Phone: 713-343-1891; Web: cpievent.com Houston November 1–2 New Orleans, La. November 14–15

Carbon Black World 2012. Smithers Rapra Silicon-Containing Polymers & Composites. (Shrewsbury, U.K.). Phone: 207-781-9618; Web: American Chemical Society, Polymer Chemistry Div. carbonblackworld.com (Washington, D.C.). Phone: 540-231-3029; Web: polyacs. San Diego, Calif. November 7–9 net/workshops/12silicon/home.htm San Diego, Calif.. December 9–12 1st International Forum on Commercializing Global Green: From Raw Materials to International SOCMA’s 91st Annual Dinner. SOCMA (Washington, Brands. Society for the Commercial Development of D.C.). Phone: 202-721-4165; Web: socma.com Industrial Biotechnology (SCD-iBIO, a SOCMA affiliate New York, N.Y. December 10

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1-800-339-7991 Available in stainless steel. www.MultiThermCoils.com Heat Transfer Fluids • Industrial Coils • HVAC Equipment Circle 15 on p. 60 or go to adlinks.che.com/40272-15 8 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Power-Gen International. PennWell (Dallas, Tex.). America (Chicago, Ill). Phone: 312-781-5180; Web: Phone: 888-299-8016; Web: power-gen.com mdna.com Orlando, Fla. December 11–13 Düsseldorf, Germany November 27–29

International Electronics Recycling Congress EUROPE (IERC 2013). ICM AG (Birrwil, Switzerland). Phone: 7th World Mycotoxin Forum and 13th International +41-62-785-1000; Web: icm.ch IUPAC Symposium on Mycotoxins & Phycotoxins. Salzburg, Austria January 16–18, 2013 Bastiaanse Communication (Blithoven, The Netherlands). Phone: +31-30-2294247; Web: wmfmeetsiupac.org Interplastica 2013 — 16th International Trade Fair Rotterdam, The Netherlands November 5–9 Plastics and Rubber. Messe Düsseldorf North America (Chicago, Ill.). Phone: 312-781-5180; Web: mdna.com Water Wastewater & Environmental Monitoring Moscow, Russia January 29 – February 1, 2013 (WWEM) 2012. International Labmate Ltd. (St. Albans, Hertfordshire, U.K.). Phone: +44-1604-879-861; Web: ASIA & ELSEWHERE wwem.uk.com Electronics Recycling Asia. ICM AG (Birrwil, Switzer- Telford, England November 7–8 land). Phone: +41-62-785-1000; Web: icm.ch Guangzhou, China November 13–16 New Horizons in Catalysis: The Art of Catalysis in Chemistry. Scientific Update (E. Sussex, U.K.). Phone: Industrial Pumps, Valves and Systems (IPVS) +44-1435-873062; Web: scientificupdate.co.uk Trade Fair & Conference — India 2012. Orbitz Ex- Prague, Czech Republic November 19–20 hibitions Pvt. Ltd. (Mumbai, India). Phone: +91-22-2410- 2801; Web: ipvs.in Valve World Expo 2012, 8th Biennial Valve World Pune, India December 14–16 ■ Conference & Exhibition. Messe Düsseldorf North Suzanne Shelley PLASTIC CONTROL VALVES FOR ALL YOUR CORROSIVE APPLICATIONS

Collins plastic control valves are highly responsive control valves designed for use with corrosive media and/or corrosive atmos- pheres. Collins valves feature all-plastic construction with bodies in PVDF, PP, PVC and Halar in various body styles from 1/2" - 2" with Globe, Angle or Corner configurations and many trim sizes and materials. Valves may be furnished without positioner for ON-OFF applications. Call for more information on our plastic control valves.

P.O. Box 938 • Angleton, TX 77516 Tel. (979) 849-8266 • www.collinsinst.com Circle 7 on p. 60 or go to adlinks.che.com/40272-07 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 9 PERFORMANCE

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O V B B R L ORION HART HART C F FOUNDATION F F O I O M E R A M I I Circle 16 on p. 60 or go to adlinks.che.com/40272-16 Edited by Gerald Ondrey October 2012 A cryogenic turbo mill generates rubber powder from recycled tires Raw material source: end-of-life and Liquid process developed by Lehigh Technolo- post-industrial rubber nitrogen A gies (Lehigh; Tucker, Ga.; www.lehight- Lehigh echnologies.com) for embrittling and milling Technologies rubber from end-of-life vehicle-tire material Cryogenic freezing is capable of generating micron-scale rubber particles that can be used in a host of rub- Cyclone ber, foam and plastic products to lower costs separation while maintaining performance. The process Turbo mill (flowsheet) depends on a specially designed Classification turbo mill that Lehigh CEO Alan Barton Warming likens to “a jet engine with teeth.” Spinning Sustainable at 2,000 rpm, the mill’s turbine rotates rows end products of plates that are studded with small metal containing MRP protrusions. These metal “teeth” impact Micronized cryogenically frozen rubber chunks that are Packaging rubber fed into the mill. powder (MRP) Through a carefully orchestrated addition of liquid nitrogen, the recycled tire rubber is taken to a temperature below its glass- Finished transition temperature (Tg), which renders the rubber chunks brittle, explains Barton. goods silos The frozen rubber is fragmented in the mill into micronized rubber powder (MRP), with of virgin material, extending the normal an average particle size distribution in the feedstock and saving money. For example, Flexible aerogels range of 105–400 µm. the powder is used at levels from 3–7% in Researchers at the NASA “We can shift the distribution to larger tire manufacturing, and from 5–40% in plas- Glenn Research Center or smaller particle sizes, as well as make it tics production. (Cleveland, Ohio; www.nasa. narrower, by altering our proprietary liquid- The main benefit of using MRP is feed- gov) have developed new nitrogen addition technique and by chang- stock cost savings (by displacing a portion flexible aerogels that could ing the pattern of teeth inside the turbine,” of the original material), and in some cases, eventually be used in highly says Barton. The MRP that comes off the the MRP imparts improved properties. Bar- insulating materials and lin ings. Aerogels, sometimes turbine is classified using cyclones to obtain ton cites examples where the powder makes called “solid smoke,” are su the desired particle sizes for particular ap- plastic floor tiles softer and less slippery, and perlightweight structures of plications, he adds. its addition to polyurethane foam for car in- silica reinforced with polymer The powder can then be introduced into teriors acts as a sound deadener. The rubber to add flexibility. Traditional customer processes, such as tire making and powder also produces a smoother, quieter silica aerogels were brittle, plastics production, to replace a percentage ride when added to road asphalt. and crumbled easily. Another type of aerogel was made from polyimide, a strong Save energy (and more) with this and heatresistant polymer, braced with crosslinks for hybrid compressor system for EOR added strength. The work was presented at the recent ast month, Lewa GmbH (Leonberg, Ger- erable energy to compress the CO2 to the pres- meeting of the American Lmany; www.lewa.de) and Burckhardt sures required (up to over 400 bars). Chemical Society (ACS; Compression AG (Winterthur, Switzerland; The two companies have developed a hy- Washington, D.C.; www.acs. www.burckhardtcompression.com) signed an brid approach that makes use of an interme- org) in Philadelphia. agreement to commercialize hybrid compres- diate step — gas liquefaction — to increase sion systems for enhanced-oil-recovery (EOR) the overall energy efficiency of the compres- HART enhancements applications. EOR — injecting high-pressure sion. First, the semi isothermal compres- Last month, the HART Com CO2 into oil wells to both reduce the crude oil’s sion is performed in multiple stages by re- munication Foundation (Aus viscosity and increase the underground pres- ciprocating compressors from Burckhardt tin, Tex.; www.hartcomm.org) sure — has been used for decades to boost the Compression. Then, at about 70 bars, the unveiled ve new enhance yield of a reservoir to up to 60%, compared to CO2 is cooled and liquefied to a tempera- ments to the HART Communi 20–40% achieved with primary and secondary ture of about 20°C. Finally, the pressure of (Continues on p. 12) recovery. Nevertheless, EOR requires consid- (Continues on p. 12) Note: For more information, circle the 3-digit number 11 on p. 60, or use the website designation. CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 CHEMENTATO R

A concept for making gasoline from ‘air’ ir Fuel Synthesis Ltd. (AFS; Darlington, AU.K.; www.airfuelsynthesis.com) has re- cently demonstrated a process for producing carbon-neutral liquid hydrocarbon (HC) fuel Air Fuel Synthesis from air-captured carbon dioxide and hydro- gen. The proof-of-concept demonstration fa- cility, located at Teesside, England produces 5–10 L/d of liquid HCs. The next step of the a dehumidifier and condenser, or another company’s three-year (2012–2015), £1.1-mil- source of clean water — is electrolyzed to lion development program is scaling up to produce hydrogen and caustic. The H2 and (Continued from p. 11) 1–10 metric tons (m.t) per day commercial CO2 are then reacted to form synthesis gas cation Protocol standard. When unit, with the long-term goal of 10-million (syngas; CO and H2) via a reverse water-gas- m.t./yr by the year 2025. shift reaction. The syngas can then be used implemented in new HARTen abled products, these enhance AFS’s process combines well-understood to make liquid HCs via Fischer-Tropsch syn- ments will give users a simple chemical techniques. First, CO2 is absorbed thesis, or methanol, which can be converted devicestatus not cation and from air (fluegas or a fermentation process, into HCs via a mobile methanol-to-gasoline easy access to WirelessHART such as in a distillery) in a sodium-hydroxide (MTG) reactor. network performance. scrubber to form aqueous sodium carbonate. The process can be used for making die- The new enhancements The Na2CO3 solution is then pumped to an sel, gasoline and aviation fuels, as well as are: Condensed Device Status electrolytic cell where the carbonate is re- methanol and raw materials for plastics and Indicators, which provide new commands and standardized duced to CO2, and the Na2CO3 solution is construction materials. Economics for the returned to the scrubber. Meanwhile, water process are being evaluated in the demon- support for Namur NE107 — either recovered from air by means of stration facility. diagnostics for operator noti cation of failure, out of speci cation, function check A polymersome that releases its cargo where needed or maintenance required; Key Performance Indicators, which everal drug delivery systems have been it claims to be the first synthesis of the are additional standardized Sstudied involving the encapsulation boroxole-containing styrene monomer and commands to support Namur of molecules in a suitable structure and its controlled radical polymerization via the NE 124 for host access to their transport through the human body. reversible addition-fragmentation and chain WirelessHART networks per Predictive solid-liquid, vapor- In particular, polymersomes — tiny hollow transfer (RAFT) method. formance indicators; HART spheres that enclose a solution — formed The group synthesized a series of sugar- Over Internet Protocol, which using synthetic block copolymers to form responsive block copolymers that self-as- speci es and standardizes solid, and vapor-liquid-solid the protocol between remote a vesicle membrane (with radii from 50 sembled to form polymersomes in water. I/O systems, multiplexers and nm to 5 µm, mostly containing an aque- It demonstrated that the polymersomes of gateways and host systems; equilibrium calculations. ous solution in their core) have been used these block copolymers could encapsulate Discrete Functionality, which for encapsulating molecules such as drugs, water-soluble cargo, such as insulin, which are new commands that en enzymes, other proteins and peptides, and could then be released only in response to able enhanced support of DNA. Those encapsulated molecules can be the presence of monosaccharides in aqueous several types of discrete and transported and released anywhere within solution under physiological pH conditions. on/off type devices with diag Good thinking. the human body. “To the best of our knowledge, there have nostics; and Infrared Device Feedback from our users is what inspires us to keep making A group led by professor Kyoung Taek been no reports describing boronic acid- Access, a new wireless inter Kim from the School of Nano-Bioscience containing block copolymers that form poly- face option for device con gu CHEMCAD better. Many features, like this one, were added to ration and maintenance that and Chemical Engineering, Ulsan National mer vesicles and exhibit sugar-responsive the software as a direct response to user need. That’s why we eliminates the need to open Institute of Science and Technology (South release of cargo in water at physiologically the device housing in hazard consider every CHEMCAD user part of our development team. Korea; www.unist.ac.kr) has reported what relevant pH,” says the group. ous areas. Get the whole story behind this user-inspired feature and learn more about how CHEMCAD advances engineering at chemstations.com/feedback. HYBRID COMPRESSOR SYSTEM because the power consumption for the reservoir pressure are not disruptive be- MCAD (Continued from p. 11) compression of liquids is lower than cause the system boosts the liquid to the E 6 . H 5

for gases. Other advantages of this ap- final pressure in a single step. C the liquefied CO2 is boosted to the re- proach are: Corrosion problems associ- The limit for piston compressors and N O E quired pressure using a Lewa triplex ated with low-pressure CO2 are avoided diaphragm pumps is approximately 150 L W B diaphragm pump. in the liquid phase; variable flowrates ton/h of acid gases, so one set of machines AVAILA The overall power savings due to liq- and gas compositions can be handled by could handle the CO2 emissions from a uefaction can be up to 15%, says Lewa, the use of speed control; and changes in 200–300-MW, fossil-fueled power plant.

12 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Engineering advanced © 2012 Chemstations, Inc. All rights reserved. | CMS-1789 9/12 CHEMENTATO R

Helmholz-Zentrum Geestacht Progress for making smart membranes ast month marked the comple- formation of membranes,” says Volker Ltion of the three-year, €3.6-million Abetz, the project coordinator and HZG E.U.-funded research project, Self- institute director. In 2011, membranes assembled Polymer Membranes (Self- could be made from chemically differ- Mem). Coordinated by the Institute of ent block copolymers for the first time. Polymer Research at the Helmholtz- It was established that solubility is a Zentrum Geesthacht (HZG; Germany; key parameter. “Very slight variations www.hzg.de), with twelve partners in the composition of the solvent can from industry and academia in Israel, suffice to prevent a membrane from Canada and Europe, the SelfMem net- forming,” he says. “Their functionality can also be ex- work studied self-organizing isopo- One achievement of SelfMem was tended by means of a subsequent coat- rous block copolymer membranes. For the production of membranes with ing of the membrane,” explains Abetz. example, fine block copolymer mem- 20-nm-dia. pores that could be used, Polydopamine, for example, increases branes were produced with an upper for example, for separation of hor- the hydrophobicity of the membrane, surface layer that is highly ordered mones and pharmaceutical substances thereby inhibiting fouling. and uniformly permeated with pores, from wastewater. Other applications The membranes are made by first which serves as a filter, and a lower for such fine-pores membranes are for pouring a solution of the block copoly- layer with a sponge-like structure that intensifying catalytic reactions and for mers onto a fleece. As the solvent evapo- provides stability (photo). gas separation. rates, cylinders are formed that grow In the beginning of the project, “we HZG has applied for four patents, in- vertically downward from the surface. knew practically nothing about struc- cluding one for “switchable” membranes A solvent exchange is then performed in ture property relationships and the in which the pore size can be adjusted a subsequent precipitation bath, which parameters that are necessary for the by variations of temperature and pH. fixes the formed structures.

Predictive solid-liquid, vapor- solid, and vapor-liquid-solid equilibrium calculations.

Good thinking. Feedback from our users is what inspires us to keep making CHEMCAD better. Many features, like this one, were added to the software as a direct response to user need. That’s why we consider every CHEMCAD user part of our development team. Get the whole story behind this user-inspired feature and learn more about how CHEMCAD advances engineering at chemstations.com/feedback. CAD EM 6 . H 5

C

N O E L W B AVAILA

Circle XX on p. XX or go to adlinks.che.com/230XX-XX Engineering advanced CHEMICAL ENGINEERING© 2012 Chemstations, WWW.CHE.COM Inc. All SEPTEMBERrights reserved. 2012 | CMS-1789 13 9/12 Circle 6 on p. 60 or go to adlinks.che.com/40272-06 A wall-less vessel CHEMENTATO R Scientists at the U.S. Dept. of Energy’s Argonne National Labo- ratory (Ill.; www.anl.gov) have discovered a way to levitate indi- A nano cage made from a stack of benzenes vidual droplets of solutions con- rofessor Kenichoro Itami and his group has a 1.8-nm inner diameter, which could taining different pharmaceuticals Pat Nagoya University (synth.chem. confine a guest molecule. In collaboration — a technique that may help in nagoya-u.ac.jp) have synthesized a cage-type with the National Institute of Advanced the development of more efficient drugs. By eliminating the vessel carbon nano-molecule, Carbon Nano-cage, Industrial Science and Technology, the re- walls — where compounds typi- composed of 20 condensed benzene rings — searchers found that the carbon nano-cage cally crystallize — the researchers C120H78. The group used a procedure it de- has a large two-photon absorption cross are hoping to better understand veloped four years ago to synthesize carbon section and a high fluorescence quantum the formation of amorphous solids nano-rings with the ability to eliminate the yield of 87%. These properties are advan- as the solvent evaporates. Most distortion of ring-type benzene structures tageous for such applications as organic drugs are crystalline, so they don’t during synthesis steps. First, they synthe- electroluminescent and organic transistor get fully absorbed by the body, sized an unstrained cyclic precursor by as- materials, optical recording materials, for says Argonne’s Chris Benmore. sembling six L-shaped units [cis-di(p-bro- high-density light storage, fluorescence who leads the study. mophenyl)cyclohexane derivative] and two imaging of bio-molecules and light sensing The scientists use an acoustic levitator to study how droplets three-way units (1,3,5-triborylbenzene) by (using a guest molecule). The structural evaporate without touching cross- and homo-coupling reactions. Then, characteristics of the C120H78 cage make anything. The droplet is placed they obtained carbon nano-cages through it suitable as a backbone structure that at the node of standing waves, acid-mediated aromatization of the cyclo- could be applied for the bottom-up syn- which are generated by two op- hexane moieties in the precursor. thesis of branched carbon nanotubes, or as posed speakers. The acoustic The nano-cage is a white solid that is a junction unit of branched carbon nano- pressure from the sound waves soluble in almost all organic solvents and tubes, which could be applied as miniscule is sufficient to cancel the effect of stable at temperatures up to 300°C. It transistors and logic gates. gravity. The system allows in-situ analysis with the high-energy X-Ray beam at Argonne’s Ad- A little gold can reduce the Pt loading in fuel cells vanced Photon Source. ❏ challenge in the development of edu.sg), led by IBN executive director, cial compressive strain effect on the Pt A polymer-electrolyte membrane fuel professor Jackie Y. Ying, have discov- shell. In contrast, a tensile strain effect cells is the durability and electro- ered that by replacing the central part would be induced by depositing Pt on a catalytic activity of platinum-based of the catalyst with a gold-copper alloy core of Au — which has a larger lattice electrocatalysts. The sluggishness of and leaving just the outer layer in parameter than Pt — leading to a lower the oxygen reduction reaction (ORR) platinum, a superior electrocatalytic catalytic activity. In addition to the sta- causes the fuel cell performance to be activity and excellent stability toward bilization effect exerted by the alloy core limited by the cathodic reaction, and the ORR are achieved. on the Pt shell during the ORR, using a high Pt loading is required for the The researchers reported the synthesis the alloy also reduces the Pt loading in cathode catalyst to achieve good activ- of core-shell AuCu@Pt nanoparticles by the resulting electrocatalyst. ity for the ORR. depositing Pt on preformed AuCu-alloy The catalytic activity of AuCu@Pt was Now researchers from the Institute nanoparticles in oleylamine. The AuCu 0.571 A/mg of Pt, which was more than of Bioengineering and Nanotechnol- alloy core has a slightly smaller lattice five times higher than that of commer- ogy (IBN; Singapore: www.ibn.a-star. parameter than Pt, creating a benefi- cial Pt catalysts.

New catalysts for Baeyer-Villiger oxidation reactions azuaki Ishihara and his group at hydroperoxide, and also purification cluding those with ketone substrates KNagoya University (Japan; www. steps for removing byproducts and and ester products. These catalysts se- ishihara-lab.net) have established a the corrosive, smelly residual catalyst lectively oxidize the C=O group, even if new, environment friendly reaction after the reaction. the substrate contains groups that are technology — using Baeyer-Villiger The new route uses hydrogen perox- sensitive to oxidation. oxidations — for selectively oxidiz- ide with an effective oxidation-accelera- In laboratory trials, the research- ing ketones into esters. The reaction tion catalyst system, both of which are ers produced -caprolactone from cy- uses hydrogen peroxide as the oxidant, easier to handle, and no byproducts are clohexanone with 80% yield after 2 and has potential as a safer alterna- produced. The researchers found that h agitation at 70°C, using H2O2 with tive to the conventional industrial two environmentally friendly catalysts Ca[B(C6F5)4] as the oxidation catalyst route for making the nylon precursor — lithium tetrakis(pentafluorophenyl) system. They also obtained the lactone -caprolactam from -caprolactone. In- borate or Li[B(C6F5)4], and cal- from 2-adamantanone with 98% yield stead of H2O2, industrial routes have cium tetrakis(pentafluorophenyl) or after 10 h agitation at 70°C using the used acetyl hydroperoxide for making Ca[B(C6F5)4] — can be used in both oxidation catalyst system of hydrogen -caprolactam, which required very hydrophilic systems with H2O2 as the peroxide, Ca[B(C6F5)4], and oxalic acid careful handling of explosive acetyl oxidant, and in lipophilic systems, in- as a promoter.

14 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Partner with the Best

KAIST

This fully functional Li-ion battery is flexible team from the Korea Advanced Institute of Science A and Technology (Kaist; Daejeon, South Korea: www. kaist.ac.kr) and Seoul National University (www.useoul. edu) led by Kaist’s professor Keon Jae Lee, claims to have developed the first prototype of a fully functional all-flexible lithium ion battery (LIB). The LIB is based on all-solid-state materials with an energy density of 2.2  103 µWh/cm3 at a current flux rate of 46.5 µA/cm2 under polymer sheet wrapping. The Korean scientists claim this is the highest energy density ever achieved for flexible batteries. The construction of the bendable thin-film battery starts with a standard fabrication process upon a brittle mica substrate (diagram). A cathode current collector, a lithium With over 50 independent subsidiar- ies and more than 220 engineering cobalt oxide cathode (LiCoO2), high-temperature annealing of LiCoO2 at 700ºC), a lithium metal anode, and protective and sales offi ces spread across the encapsulation multilayers are sequentially deposited on world, SAMSON ensures the safety the substrate (Step 1). and environmental compatibility of The next step is physical delamination of the mica sub- your plants on any continent. strate using sticky tapes (Step 2). The flexible LIB from substrate delamination is then transferred onto a PDMS To offer the full range of high-quality (polydimethylsiloxane) polymer sheet (Step 3), where the control equipment used in industrial surface bondability of the PDMS helps the stable settle- processes, SAMSON has brought ment of the flexible LIB. The final step is capping of the together highly specialized compa- fabricated flexible LIB with another thin PDMS sheet to nies to form the SAMSON GROUP. enhance its mechanical stability (Step 4). The thin film LIB is capable of a maximum 4.2-V charg- ing voltage and 106-µAh/cm2 capacity. The bendable LIB enables the fabrication of an all-in-one flexible LED dis- play integrated with a bendable energy source. This novel SAMSON AG · MESS- UND REGELTECHNIK approach can be expanded to various high-performance Weismüllerstraße 3 flexible applications, such as thin-film nanogenerators, 60314 Frankfurt am Main · Germany thin-film transistors and thermoelectric devices. ■ 19 on p. 60 or go to adlinks.che.com/40272-19 Circle Phone: +49 69 4009-0 · Fax: +49 69 4009-1507 E-mail: [email protected] · www.samson.de SAMSON GROUP · www.samsongroup.net A01120EN Newsbriefs

CFATS administration needs improve- STB SEEKS RATE PROTECTION ment, testimony argues FOR CAPTIVE RAIL SHIPPERS he U.S. Surface Transportation Board (STB; Washington, he Society of Chemical Homeland Security (DHS; TD.C.; www.stb.dot.gov) announced two initiatives to explore TManufacturers and Affili- Washington, D.C.; www. ways to further protect captive shippers — those having no ates (SOCMA; Washington, dhs.gov). Specifically, Leary practical alternative carrier for transporting their goods — D.C.; www.socma.com) testi- highlighted communications from unreasonable rail rates. First, the STB proposed to reform fied before Congress last issues with DHS and dif- its rules on how it resolves rate disputes to ensure that all cap- month that poor implemen- ficulties budgeting for com- tive rail shippers have a meaningful way to challenge rates. tation of the nation’s chemi- pliance. Leary said small Second, the STB is considering a proposal submitted by the National Industrial Transportation League (NITL) to increase cal security regulations has companies cannot afford to rail-to-rail competition. created burdens on small spend on security in advance The centerpiece of the STB’s rate-rules proposal removes chemical companies. unless they are certain it the limitation on relief for cases brought under the Simplified Testifying on behalf of will lead to compliance. Stand-Alone Cost (SAC) alternative. “Our goal is to encourage SOCMA before the House Also testifying was Timo- shippers to use a simplified alternative to a Full-[Stand Alone Subcommittee on Environ- thy Scott, chief security Cost] analysis that is economically sound, yet provides a less ment and the Economy, officer at the Dow Chemical complicated and less expensive way to challenge freight rates Matthew Leary, corporate Co., who also represented by discarding the requirement that shippers design a hypo- EHS&S manager for Pilot the American Chemistry thetical railroad to judge a railroad’s real-world rates,” the STB Chemical Co. (Cincinnati, Council (ACC; Washington, wrote in a recently issued decision. Captive shippers have long stated that they do not bring rate Ohio; www.pilotchemical. D.C.; www.americanchem- disputes to the STB because of the high litigation costs associ- com), discussed several is- istry.com). Scott said that ated with the Board’s complex Stand Alone Cost test, tradition- sues impeding compliance while the CFATS concept is ally used to resolve major rate cases. To provide rail customers with the Chemical Facility sound, problems with imple- with a lower-cost, expedited alternative to this test, STB sim- Anti-Terrorism Standards menting the standards — plified evidentiary procedures, but because the methods used (CFATS), which are admin- particularly in the area of are less precise than those used in full SAC cases, the Board istered by the U.S. Dept. of personnel surety — are real. capped the amount of relief available under them. ❏ Shell to construct world’s first ECHA seeks public consultation oil sands CCS project on substances of high concern oyal Dutch Shell (The the world’s first commer- he European Chemicals prepare Annex XV dossiers RHague, the Netherlands; cial-scale CCS project to TAgency (ECHA; Helsinki; for 37 of the substances www.shell.com) says it will tackle carbon emissions in Finland; echa.europa.eu) on its behalf, and other go ahead with the first the oil sands, and the first has opended a public com- countries have put forward carbon capture and storage CCS project in which Shell ment period on 54 poten- proposals for the other 17 (CCS) project for an oil- will hold majority owner- tially harmful substances, proposed substances. sands operation in Canada. ship and act as designer, including 44 that are Comments can be posted The project will be built on builder and operator. It will proposed to be identified on the ECHA website until behalf of the Athabasca Oil also form the core of Shell’s as substances of very high October 18, 2012. The Sands Project joint-venture CCS research program and concern (SVHCs) because Member State Committee owners (Shell, Chevron and help develop Shell’s CO2 of their classifications as will take comments into ac- Marathon Oil) with support capture technology. carcinogenic, mutagenic count when seeking agree- from the governments of The CO2 will be trans- or toxic for reproduction ment on the identification Canada and Alberta. ported through an 80-km (CMR). The list of sub- of all proposed substances The Athabasca Oil Sands underground pipeline to stances proposed for identi- as SVHCs. project produces bitumen, a storage site north of the fication as SVHCs include ECHA is also seeking which is piped to Shell’s Scotford site. Here, the CO2 four fluorodecanoic acid information on the uses of Scotford Upgrader near will be injected more than compounds, several phtha- the substances. This would Edmonton. Starting in late 2,000 m underground into lates and lead compounds, include data on tonnages 2015, the project will cap- a porous rock formation as well as diazene-1,2 di- per use and exposures or re- ture and store, deep under- called the Basal Cambrian carboxamide, methoxy ace- leases resulting from these ground, more than 1 mil- Sands. Sophisticated moni- tic acid and N,N-dimethyl uses. Information on safer lion metric tons a year of toring technologies will formamide. alternatives and techniques, CO2 produced in bitumen ensure the CO2 is perma- The European Commis- and supply-chain structure, processing. The project is nently stored. sion has requested ECHA to are also welcome. ■

16 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Siluria Technologies Newsfront SHALE GAS USHERS IN ETHYLENE FEED SHIFTS

Growth in North American ethane cracking FIGURE 1. Siluria Technolo- gies has developed a catalyst has wider effects for the CPI, while some companies for the oxidative coupling of methane (OCM), potentially opening the door to commer- look to harness methane for ethylene cial-scale ethylene directly from methane in one step

ncreasing production of natural TABLE 1. NORTH AMERICAN ETHYLENE CAPACITY GROWTH gas from hydraulic fracturing of Company Location Capacity, thou- Start up year shale deposits has fundamentally sands of ton/yr I altered the landscape of chemi- Dow Chemical Freeport, Texas 1,906 2014–2017 cal production in North America. The Ineos Lake Charles, La. 1,361 2018 higher margins on steam-cracking eth- CP Chem Baytown, Tex. 1,134 2016–2017 ane to produce ethylene have resulted Braskem/Idesa Coatzacoalcos, Mexico 998 2015 in significant feedstock shifts in the Shell Chemical Pennsylvania 907 2016+ U.S. over the past two years. Numer- Formosa Plastics Point Comfort, Tex. 799 2015 ous chemical producers are expanding ethylene capacity to take advantage LyondellBasell Texas and Illinois 658 2012–2014 of the increased availability of ethane Dow Chemical Hahnville, La. 363 2012 (4th Q) from natural gas. The shift toward Williams Lake Charles, La. 272 2013 (3rd Q) using more ethane as a feedstock for Westlake Chemical Lake Charles, La. 104 2012 ethylene is generating a number of Ineos Chocolate Bayou, Tex. 104 2013 ripple effects for other chemicals, in- Total 8,607 cluding tightness in the propylene Source: IHS Chemical and butadiene markets. Meanwhile, and butane), and some are very “wet,” fabrics; coverings, pipes, conduits as manufacturers in energy-intensive containing from a few percent up to and assorted construction materials; industries take advantage of lower en- even 20% NGLs. Parts of the Marcel- drums, bottles and other containers; ergy costs offered by shale gas, other lus shale in the eastern U.S. are very and antifreeze, solvents and coatings. companies continue the pursuit of an wet, for example, notes Heinen, while According to an analysis by the alternative route to ethylene using the Eagle Ford and Barnett shales in American Chemistry Council (ACC; methane as the feedstock. Texas produce dryer gas (more meth- Washington, D.C.; www.american- Higher shale-gas production has re- ane with less NGLs). chemistry.com), the additional output sulted in a significant and longterm of chemical derivatives generated by change in the relationship between Ethane to ethylene a 25% increase in ethane production petroleum and natural gas prices, ex- Driven by a wide range of derivatives, would translate to $18.3 billion worth plains Russell Heinen, director of IHS ethylene is the most-produced organic of bulk petrochemicals and organic Chemicals (Englewood, Colo.; www.ihs. chemical in the world, with volumes intermediates, as well as $13.1 billion com). “This change in price relation- expected to top 160 million tons in worth of plastics resins and $1.0 bil- ships has kept prices for ethane low 2012, accounting for $150 billion in lion of rubber. relative to naptha, which is still the sales. Major polymers and chemicals dominant feedstock for ethylene pro- made from ethylene include: low-den- New capacity ducers worldwide,” he says (Figure 2). sity polyethylene (LDPE); linear low- A major driver of the increasing eth- IHS is preparing a report, “The Game density polyethylene (LLPDE); and ane-cracking capacity is the ratio be- Has Changed: The Influence of Shale high-density polyethylene (HDPE); tween crude oil and natural gas prices, Development on the Global Chemical as well as polyvinyl chloride; ethyl- which has been generally increasing Industry,” to be released this month. ene oxide; ethanol; ethylene propylene since January 2009, and is at histori- Shale deposits vary greatly in the diene monomer (EPDM) and others. cally high levels (40 to 1 or higher). composition of natural gas. Some End-use markets include wire and “To date, most new capacity for eth- areas contain virtually no natural cable insulation; consumer, industrial ylene has come through retrofits and gas liquids (NGLs; ethane, propane and agricultural packaging; woven expansions, but the bulk of new capac-

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 17 WIDER SHALE GAS EFFECTS

Newsfront host of additional effects of the shale gas boom is generating profound changes across the Achemical industry and beyond, including rising methanol and ammonia production capacity in the U.S., says ACC economist Martha Gilchrist-Moore, who will be speaking about the implica- tions of the shale gas boom at ChemInnovations 2012, along with IHS’ Heinen (see p. 24D-1). ity from newly built plants will The availability of shale gas will also have a profound effect on manufacturing more generally. start to come online in 2016 and Energy-intensive sectors like iron and steel, plastics, glass, rubber, aluminum, fabricated metals 2017,” says IHS’s Heinen. and papers all stand to gain from inexpensive shale gas, she says. Also, combined heat and Since 2010, 450,000 ton/yr power cogeneration plants are even more economically attractive, she notes. of ethylene production capac- ity have been added through retrofits, notes Felipe Tavares, director of In- ral gas is available, new demands for upgrades and expansions in the U.S., tratec (Houston; www.intratec.com). methane are needed, says Rahul Iyer, and producers have announced over 5 Several on-purpose propylene produc- senior director of corporate develop- million ton/yr of new ethylene capacity tion alternatives exist, including those ment at Siluria Technologies (San that are scheduled to come online by using NGLs — propane dehydrogena- Francisco, Calif.; www.siluria.com). 2018 (Table 1). And since the additional tion (PDH) and propylene production Dallas Kachan (Kachan & Co.; San ethane potential would allow about 11 via metathesis chemistry. Francisco, Calif.; www.kachan.com), million ton/yr of ethylene, there is still PDH is a catalytic process in which an analyst and consultant in the clean plenty of room for new capacity to be the hydrogen byproduct can be used technology industry, points out that added to balance potential supply with as fuel for the reaction. Metathesis is the energy and capital intensity re- demands. That means more ethylene a catalyzed reaction between butenes quired for steam cracking of ethane capacity is likely, Heinen says. and ethylene where double bonds are provides an incentive to make ethyl- Industry faces several challenges reformed. Propylene technology is ene in alternative ways. Commercially associated with the added capacity, among the first topics covered in In- viable ways to make ethylene directly Heinen notes, including the ability to tratec’s “Knowledge Base,” an online from methane, if successful, could be bring capacity online without delay, encyclopedia of chemical technology a watershed moment for the chemical and the ability of ethylene producers and economics. The tool can be found and petroleum industries, Kachan re- to work out the supply logistics of han- at: base.intratech.us. cently wrote in a blog post. dling nearly 300–400 thousand bbl/d Capacity growth for propylene from Significant activity is ongoing to- of new ethane by 2020. Also, Heinen PDH is poised to grow significantly. ward commercialization of methane- points out that other potential chal- The Dow Chemical Co. (Midland, to-ethylene technologies, with many lenges are that U.S. ethylene supply Mich.; www.dow.com) has announced startups — some announced and some increases could impact pricing; and plans for a 750,000 ton/yr PDH plant “undercover” — working on various environmental concerns related to in Freeport, Tex., using technology technologies, while university and shale-gas drilling could spur legisla- from UOP LLC (Des Plaines, Ill.; www. government laboratories also attack tion restricting hydraulic fracturing. uop.com). Formosa Plastics and Enter- the problem, according to research by Another challenge for ethylene prise Products Partners LP (Houston; Kachan & Co. The major integrated producers is that some of the newer www.enterpriseproducts.com) has also petroleum companies, including Chev- crackers are ethane-specific, giving up announced plans for PDH facilities on ron, ExxonMobil, Shell and BP hold a feedstock flexibility to focus on eth- the U.S. Gulf Coast. surprisingly wide-ranging portfolio of ane cracking, so future growth might Lummus Technology / CB&I Co. (The patents for methane-to-ethylene tech- be hindered if economics change and Hague, the Netherlands; www.cbi.com) nologies, and several large chemical flexibility is needed. is currently the only licensor to offer companies also hold some intellectual an olefin metathesis process, known property in this area (BASF, Lubrizol, On-purpose propylene as olefin conversion technology (OCT), SABIC, GE, Honeywell and others), The shift to lighter feedstocks for eth- to make propylene from ethylene and Kachan research found. ylene (using more ethane) is beginning butenes. In cases where only ethylene Methane-to-ethylene technologies to have ripple effects that are likely is readily available, Intratec’s Tavares are being considered for use in remote to grow going forward. When steam- says the metathesis process could be areas where natural gas associated cracking naptha or gas oil, propylene combined with a dimerization plant, with crude oil drilling is flared, or re- and other chemicals are formed as which converts ethylene to 2-butene. mote gasfields where no pipelines exist co-products alongside ethylene; but and transporting the gas is difficult. when ethane is the feedstock, ethyl- Utilizing methane Smaller-scale gas-to-liquids (GTL) ene is the primary product, with mini- While methane from natural gas will technologies are needed for areas mal co-products formed. So the shift to continue to play a prominent role as with “stranded gas,” says Sulkhan ethane as a feedstock has resulted in a cleaner-burning alternative to coal Davitadze, an investment director at tighter supplies of three- and four-car- for power generation, its abundance Bright Capital (Moscow, Russia; www. bon chemicals, particularly propylene (~10 times more than ethane in natu- bright-capital.com), a venture capital and butadiene, which is likely to raise ral gas) and price (about half the price firm with a portfolio of companies in prices for those chemicals, says IHS’ of ethane) is spurring a wide-ranging the energy and chemicals areas. Heinan (Figure 3). effort to utilize methane directly as A number of smaller-scale GTL Tightness in propylene supply has a feedstock for ethylene and other processes exist, some using a Fischer- improved the cost-competitiveness chemicals, rather than burning it as Tropsch (F-T)-based approach and of on-purpose propylene production, fuel (Figure 1). Since so much natu- some taking different paths. All are

18 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Source: IHS Chemical SynFuels International U.S. ethylene production by feedstock 30,000

25,000

20,000

15,000

Metric tons Metric 10,000 Heavier Propane 5,000 Butane Ethane

0

2011 2010 2012 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2001 2002 2003 2004 2005 2006 2007 2008 2009 2000 FIGURE 2. Shale gas has pushed natural gas and ethane production higher. Fore- casts indicate the production will rise further FIGURE 4. Source: IHS Chemical SynFuels International uses methane in pyrolysis reactors Steam cracker propylene and butadiene production to generate acetylene, which is then Ratio to ethylene hydrogenated to ethylene 33 8

31 8 gives rise to catalyst active sites that 29 can select ethylene formation over 7 non-specific oxidation of methane. The 27 7 catalyst is a doped metal oxide of tran- 25 6 sition metals that is designed for com- 23 patability with existing petrochemical- 6 21 industry infrastructure. 5 Propylene/ethylene, % Propylene/ethylene, 19 Propylene/ethylene % Butadiene/ethylene, The Siluria technology has a num- ber of advantages over F-T approaches 17 Butadiene/ethylene 5 because it can be accomplished in 15 4 one step, at lower temperatures, and 2011 2010 2012 works well with existing hydrocarbon 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2001 2002 2003 2004 2005 2006 2007 2008 2009 2000 processing equipment. Siluria’s OCM FIGURE 3. Propylene and butadiene production (shown as a ratio to ethylene) have fallen as a result of the shift to lighter feedstocks by ethylene producers technology is an exothermic reaction, so it requires less energy input, and potentially useful, but it’s not clear yet oped by SynFuels. The company oper- the heat given off by the process can what the economics will turn out to be, ates a fully integrated GTL demon- be harvested to drive the process. “We Davitadze remarks. stration plant in Bryan, Tex., capable believe we are the first to develop a SynFuels International (Dallas, of processing 50,000 ft3/day of natural commercially viable, scalable process Tex.; www.synfuels.com) is looking gas into gasoline blendstock. for OCM,” Tchachenko says. to make higher-value chemicals from Siluria Technologies is trying to Siluria’s catalyst-discovery engine methane without using Fischer-Trop- commercialize a single-step methane- has the potential to develop other cata- sch chemisty. SynFuels has designed to-ethylene process. The company just lysts to make different products. Silu- a non-catalytic, water-jacketed, fixed- announced plans to build a demon- ria’s Iyer says the company will be able bed reactor that pyrolyzes methane, stration facility for its process, which to achieve the economics enjoyed by a generating a mixture of gases com- is based on oxidative coupling of meth- world-scale plant in a much smaller posed mostly of acetylene, as well as ane (OCM) chemistry. According to Si- facility, so significant capital-expense some carbon monoxide and hydrogen luria CEO Alex Tchachenko, construc- savings are possible. (Figure 4). The gas mix is fed into an tion on the demonstration plant will OCM is also of interest to the Pol- absorber that separates the acetylene begin in 2013, and it will be capable ish national research laboratory Fer- from the other gases. of producing hundreds of thousands tilizer Research Institute (Pulawy, Acetylene is then hydrogenated, of gallons per year. Siluria’s technol- Poland; www.ins.pulawy.pl). Scien- while still absorbed, using some of the ogy depends on a carefully made cata- tists there have built a pilot plant for hydrogen produced in the initial pyrol- lyst that promotes ethylene formation a methane-to-ethylene facility based ysis step. A specially designed hydro- over non-selective oxidation reactions on OCM. Also, UOP has reportedly genation catalyst that tolerates high (Chem. Eng., December 2010, p. 12). proved, in the laboratory, a one-step levels of carbon monoxide is used. The Siluria’s technology is attractive process for directly converting meth- process, based on technology originally because it’s a one-step process that is ane to ethylene. The company is look- conceived at Texas A&M University capital efficient as well as energy ef- ing for partners to build a pilot plant (College Station, Tex.; www.tamu.edu), ficient, Davitadze comments. for the process. UOP says its technol- is capable of producing polymer-grade Using a genetically engineered bac- ogy could potentially save 40% of the ethylene in 96% yields from acetylene. teriophage (bacteria-infecting virus) as cost of ethane-based ethylene. ■ The ethylene can also be taken fur- a template for material growth, Siluria Scott Jenkins ther to gasoline blendstock (a mix of scientists developed a catalyst mate- C to C hydrocarbons) through an rial that has a unique crystal structure Editor’s note: An expanded version of this arti- 4 12 cle, with additional background information and oligomerization technique also devel- and surface morphology. The structure graphics can be found at www.che.com.

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 19 Newsfront A STEAMY SITUATION

Short staffed and lacking expertise, many chemical processors don’t realize the full potential FIGURE 1. of their steam systems Desuperheaters reduce the temperature of superheated steam for opti mal heat transfer and efficiency, as well as reduced degradation of system components

oday’s chemical processors must Illustrations: Kadant cope with rising labor costs, in- Johnson creasing global competition, Tescalating fuel costs and more- stringent safety and environmental regulations. To improve productivity and reduce costs in today’s competi- FIGURE 2. tive environment, many facilities Steam jet thermo are operating leaner than even be- compressors are fore. And, downsizing strategies designed to boost have seen the reduction of mainte- FIGURE 3. lowpressure Directsteaminjec steam by mixing nance staff, which often results in tion water heaters are used it with highpres a decrease of in-house steam-engi- to rapidly and accurately take low sure steam in CPI neering knowledge and experience. pressure steam and use it to directly heat applications “For today’s chemical processors, water and waterbased slurries by injecting maintenance and improvement of steam directly into the uid steam systems are low on the list of priorities,” says Neil Davies, product marketing manager for Spirax Sarco most efficiency out of an existing “While some are beginning to see that (Blythewood, S.C.; www.spiraxsaco. system, reducing carbon footprint they can make improvements that com). While this is understandable, and reducing costs associated with will increase efficiency and some un- it is not necessarily wise. Not only do utilities, water and chemical require- derstand that they can capitalize on processors rely on their steam sys- ments for treated water. For this the waste energy, they just don’t know tems to lend process efficiency and reason, steam handling experts offer exactly how to do the things they need uptime, but steam can also provide a services such as audits, which often or want to do, especially regarding lost versatile energy medium for heating reveal not only where steam is being energy or heat recovery.” and sterilization processes. wasted, but also optimized solutions Working with an expert is indeed Although the modern steam system and proposals, with suggested busi- worthwhile. For example, Spirax is very efficient, there is always room ness proposals to help demonstrate a Sarco audits hundreds of steam sys- for improvement in existing systems return on investment. tems annually in the U.S. and has and potential for waste steam to be re- “Even though [processors] may not identified actions required to mod- cycled back into the process. However, realize it, steam utilization is one ernize plants, using best practices, lacking staff, experience and knowledge of the biggest areas processors need technologies and products to save of today’s technologies, many proces- assistance with,” says Mike Sneary, 20.7-billion lb/yr of steam energy and sors are ignoring these opportunities. business development manager with reduce carbon dioxide emissions by Tapping into available expert ad- Kadant Johnson (Three Rivers, Mich.; 1.4-million ton/yr. vice can be the ticket to getting the www.kadantsteamsolutions.com). And on an individual basis, says

20 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 STEAM CYCLE SOLUTION CAN OPTIMIZE PERFORMANCE FOR POWER PLANT BOILERS

team plant operators are looking for control solutions that ages,” says Pezalla. “The advantage of this control system is that Swill help them optimize boiler efficiency by reducing fuel it is an open system that works with any type of boiler and can consumption while reducing emissions, according to Bill be implemented during a short maintenance outage leading to Pezalla, global energy industry manager for GE Intelligent Plat- the realization of rapid fuel and water savings. These efficiencies forms (Charlottesville, Va.; www.ge.com). High-performance need to be factored into the total cost of ownership when purchas- plants under 300 MW can meet these needs with control solu- ing control systems.” tions based on expertise in steam-cycle generation management, “Adding boiler and turbine auxiliary-equipment control strategies which can help reduce fuel usage while allowing boilers to run provides a more comprehensive solution,” notes Craig Thorsland, safely and efficiently. steam-cycle solutions leader for GE Intelligent Platforms. “Opti- For example, GE’s Steam Cycle control solution is based on a mally, the overall control solution reduces the need for operator flexible and scalable DCS, Proficy Process Systems, along with intervention. This stabilizes steam production and frees operators pre-packaged advanced combustion-control algorithms and strat- to focus on plant operations. With stable and consistent opera- egies for fossil and biomass fuels to achieve operational benefits tions, the thermal stresses on the boiler and turbine are reduced, and mitigate risk. extending their lifecycles.” These advanced combustion-control algorithms and strategies op- Safety is a concern and the Steam Cycle solution addresses that timize the combustion process to reduce fuel usage 3 to 5%, which concern with drum-level control strategies that allow water levels allows them to better meet stringent emissions regulations. In addi- to be properly maintained to avoid boiler failure. “It is critical to tion, the technologies keep equipment safe and protected by main- keep the water level in the boiler at the proper level,” explains taining the water level in the boiler to prevent damage. Because Thorsland. “If it falls too low, the boiler can be damaged, or worse the control algorithms and strategies are pre-engineered, they are yet, fail with problematic consequences. Control strategies can capable of reducing system implementation time by 50 to 80%. compensate for varying loads and the resulting increases or de- “Power plants are running longer with shorter maintenance out- creases in water level.” ❏

Sneary, steam system improve- traps first, then cold steam traps and (CPI) in applications such as drying, ments for many facilities can identify finally closed steam traps. And finan- filtration, distillation, absorption, 50,000 to 100,000 lb of lost steam en- cial justification is often offered to mixing, vacuum packaging, freeze ergy, which, if stopped, can result in increase the chances of investment in drying, flash cooling, deaerating and a tremendous savings. But, he says, the system. dehydrating. to reap the savings, processors need Once the expert fully understands Desuperheaters are intended to re- the assistance of an expert. “Often, the complete process that takes place duce the temperature of superheated folks in the facility just look at the in the facility, and if the processor steam for optimal heat transfer and wasted steam and think ‘this is the chooses, the expert can then make efficiency, as well as reduced degra- way it’s always been,’ or they may recommendations on how to modify dation of system components. The ef- not be aware of new equipment that the system in an effort to move some ficient geometry allows for direct in- could benefit their steam system. of the wasted energy into another stallation into the steam pipeline with But, people from the outside can see process. “The process is all about un- flanged connections. the wasted energy, figure out ways to derstanding their facility and their And, direct-steam-injection water recover it and use it elsewhere and process and then trying to figure out a heaters (Figure 3) are used to rap- point out how modern equipment can way to save them money,” says Sneary. idly and accurately take low-pressure assist with the process. So, it’s really “And often we save them money by steam and use it to directly heat water worth it to tap into this expertise.” turning wasted steam into usable and water-based slurries by injecting The first step is to find a firm that has steam, using a wealth of equipment steam directly into the fluid. They are the experience to provide a range of ser- for this purpose that they may not yet used in CPI applications including vices from onsite auditing to steam trap know exists.” boiler feedwater preheating, fibrous surveys to the ability to recommend and He says that currently products are slurries such as pulp stock and bio- provide turnkey installations, as well available from many steam system mass pre-treatment, sanitization and as the knowledge and understanding to providers, such as thermocompres- tank cleaning and anaerobic treat- provide financial information that will sors, desuperheaters (Figure 1) and ment of organic waste. justify any improvements. water-jet heaters, to make heat recov- While just a simple steam-trap From there, an audit, including a ery easier and more affordable than survey can yield hundreds of thou- steam trap survey that reveals the ever before. sands of dollars a year in lost steam condition of the steam traps and For example, steam-jet thermo- savings and energy reductions, it which ones have failed, closed or gone compressors (Figure 2) are designed may provide the impetus to further cold, is normally conducted. Follow- to boost low-pressure steam by mix- investigate the possibility for heat ing this audit, recommendations are ing it with high-pressure steam recovery projects that could boost made to repair or replace failed steam in the chemical process industries these savings even more. ■

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 21 RECEIVE Newsfront

FULL ACCESS STEAM-HANDLING Engineering’s to ALL of Chemical PRODUCTS Facts at Your Fingertips articles in one convenient location. Free float trap for facilities with corrosive environments This free float trap (photo) is suitable for the food industry, plants with cor- rosive environments and petroleum refineries and petrochemical plants where steel materials are required. TLV The J3X provides corrosion resistance through the use of high quality CF8 stainless-steel material. It delivers They can be installed in any position, continuous, smooth, low-velocity con- but if installed in horizontal pipes, it densate discharge as process loads is important to make sure the cover is vary. The float has an unmatched on top. — Flowserve, Irving, Tex. sealing performance and is designed www.gestra.com for severe service operations. Rated for 1,740 psig hydraulic shock, the This steam trap resists corrosion free float provides waterhammer re- from clean and pure steam EACH INFORMATION PACKED PDF sistance. The product also offers the The BTS7.1 stainless-steel clean steam article includes graphs, charts, tables, possibility for inline repairs and a trap is constructed to withstand cor- equations and columns on the full thermostatic air vent that automati- rosion from clean and pure steam ap- chemical engineering processes you cally vents air for easier startups. — plications. The unit is pressure rated deal with on a daily basis. This is the TLV Corp., Charlotte, N.C. to ASME standards and is designed to tool you will come to rely on, referring www.tlv.com remove condensate from clean steam back to the information again and systems with minimal backup, mak- again with just the click of a mouse. Steam generators and fluid ing it suitable for the pharmaceutical, heaters offered in many sizes biotechnology and food-and-beverage Facts at Your Fingertips Topics Include: Offered in 18 sizes ranging from 25 to industries. The self-draining trap  Conservation Economics: Carbon 1,000 boiler hp and 862 to 34,500 lb/h operates close to steam saturation Pricing Impacts of steam, these controlled-flow water- temperatures, reducing condensate  Distillation Tray Design tube boiler units are built to appropri- backup and effectively venting air, en-  Burner Operating Characteristics ate national and local standards. Units suring full sterilization. The smooth  Measurement Guide for are designed to burn natural gas, pro- surfaces provide a free-draining Replacement Seals pane, light oil and heavy oil, as well as surface, reducing the risk of bacte-  Steam Tracer Lines and Traps a combination of these fuels and are rial growth and product blockage. —  Positive Displacement Pumps available with steam design pressures Spirax Sarco, Inc., Blythewood, S.C.  Low-Pressure Measurement for up to 3,000 psig. A Superheat version www.spiraxsarco.com Control Valves of the E-Series product, which provides  Creating Installed Gain Graphs superheated steam is available in a va- A disc trap that performs with  Aboveground and Underground riety of sizes for a range of steam pres- low-cost maintenance Storage Tanks sures and temperatures. — Clayton Part of the PowerDyne thermody-  Chemical Resistance of Industries, City of Industry, Calif. namic steam trap family, the stainless Thermoplastics www.claytonindustries.com steel P46SRN has a replaceable mod-  Heat Transfer: System Design II ule that allows the unit to be serviced  Adsorption Thermostatic steam trap is without removing the trap body from  Flowmeter Selection unaffected by waterhammer installation. With the same capacity,  Specialty Metals The Gestra MK 36/51 thermostatic pressure and temperature specifica-  Plus much, much more… 17872 steam trap with a corrosion-resistant tions as the cast steel version, the membrane regulator (thermostatic P46SRN has a corrosion-resistant capsule) is unaffected by water ham- stainless-steel body. Designed for ef- mer. An integral strainer and stan- ficient performance, low-cost mainte- Receive fullfull accessaccess todaytoday byby visiting dard capsule for discharge are avail- nance and durability, the product is a http://store.che.com/product/factswww.omeda.com/cbm/facts able with virtually no backing up. The suitable for steam mains, tracers and traps are suitable for draining satu- coils. — TLV Corp., Charlotte, N.C. rated steam lines and steam tracers www.tlv.com ■ and can also be used for air venting. Joy LePree

22 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Gasmet Technologies Honeywell Process Solutions FOCUS ON Gas Detection & Handling

Industrial Scientific

Trolex

Manufacturer’s warranty period Detector now approved DX4040 with a handheld PDA. How- extended to two years for underground mining ever, the most important development This manufacturer of gas detection The lightweight and highly configu- lies in the ability of the device to iden- and environmental monitoring sys- rable Ventis MX4 (photo) is capable tify unknown gases in the field (at tems has extended its warranty period of detecting from one to four gases, the touch of one button) when using to two years, providing additional cov- including oxygen (O2), methane (CH4) a new version of the unit’s Calcmet erage for all of its equipment. The com- and any two of the following toxic software on a Windows tablet. The pany also offers a service contract spe- gases: carbon monoxide (CO), hydrogen DX4040 is unique because it is able cifically tailored to requirements that sulfide (H2S), nitrogen dioxide (NO2) to identify both organic and inorganic cover the maintenance of its products and sulfur dioxide (SO2). The Ventis compounds, while also storing sample (photo). When customers call for prod- can be configured with CH4, CO, and spectra for post-measurement analysis uct support, they speak directly to an O2 sensors for many everyday mining using a chemical library of over 5,000 engineer, not a call center. — Trolex applications, or it can be configured compounds. There are no sensors that Ltd., Stockport, Cheshire, U.K. with CH4, CO, O2 and NO2 sensors, might need future replacement. No www.trolex.com making it ideal for mines using diesel sample preparation is required, and equipment. In fact, the Ventis MX4 has calibration is simply a zero check with PID detects VOCs and up to recently received MSHA approval for nitrogen or air. — Gasmet Technolo- four more hazards underground mining. The Ventis with- gies Oy, Helsinki, Finland Rugged and durable, the GasAlertMi- out pump has been certified by MSHA www.gasmet.fi cro 5 PID (photo) measures for photo- under Title 30 CFR, Part 22 when used ionization detectable (PID) VOCs with the standard or extended runtime O2 analyzer approved for hazard- (volatile organic compounds), while si- lithium-ion battery packs. The com- ous-area use in North America multaneously monitoring and display- pany anticipates that the Ventis with XTP601 Oxygen Analyzer (photo, p. 24) ing up to four additional atmospheric pump will receive MSHA approval has attained CSA certification, making hazards, including oxygen, combus- later this year. — Industrial Scientific it approved for use in hazardous areas tible gases and a range of toxic gases. Corp., Pittsburgh, Pa. in the U.S. and Canada. The instru- The PID sensor adds photo-ionization www.indsci.com/ventis ment already carries certification from detection capabilities. Compact and ATEX and IEC Ex, and the addition of lightweight, with a concussion-proof, Measure thousands of gases CSA broadens its global coverage. The waterproof IP66/67-rated boot, it is in the fi eld XTP601 uses thermo-paramagnetic well suited for harsh industrial envi- The DX4040 (photo) is the second measurement technology to make ac- ronments. The portable gas detector generation of what is said to be the curate and stable measurements of ox- provides multi-language support in world’s first truly portable FTIR (Fou- ygen in background gases such as hy- English, French, German, Spanish rier transform infrared) spectroscopy drogen, nitrogen and carbon dioxide. It and Portuguese and offers visual, au- analyzer, a technology that brought is capable of measuring oxygen ranges dible and vibrating alarms. — Honey- laboratory-grade gas analysis into the from 0–1% up to 0–25%. Typical haz- well Process Solutions, Houston field. Up to 25 gases can be displayed ardous applications include monitor- www.honeywell.com simultaneously when operating the ing of inerting or blanketing gases in

Note : For more information, circle the 3-digit number CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 23 on p. 60, or use the website designation. Focus

petroleum refining, chemical and phar- maceutical industries. The analyzer, which is housed in a tough flame-proof General Monitors Oldham Gas and explosion-proof housing, is avail- able in three versions: a blind trans- mitter; a unit with status LEDs or a full-display unit. This last version has a touch-screen interface, which allows through-the-glass interaction, elimi- nating the need to remove the analyzer lid (except for service). All versions are supplied with two 4–20-mA outputs, two concentration alarms Modbus RTU over RS485 protocol and applica- tion software as standard. — Michell Instruments, Ely, Cambridgeshire, U.K. www.michell.com

Fixed gas detector is protected against dust and water The OLCT IR infrared fixed gas detec- tor (photo) has been tested according to IEC/EN 60529 and gets the IP67 protection degrees. As a result, the Michell Instruments Sierra Monitor OLCT IR is totally protected against to atmospheric concentrations above via open junction box terminals for com- dust and against the effect of immer- 5,000 ppm is considered unhealthy, missioning. ELDS Version 1.2 Wireless sion in up to 1 m of water, putting the making careful monitoring crucial is particularly beneficial for OPGD sys- OLCT IR ahead of competitors’ prod- at lower levels. The IR700 features a tems installed high in the air or under ucts, says the manufacturer. With a true fail-to-safe design for dependable floor grates. Version 1.2 also features stainless-steel 316L enclosure, dual gas detection performance, heated op- expanded gas applications for high- source, four-beam technology, and tics to eliminate condensation, and a level H2S detection at 0–15,000 ppm in heated optics the OLCT IR is said to dirty optics indicator informs the user FPSO Vent Gases, low-level ppm ammo- be one of the most reliable infrared the device must be cleaned before the nia OPGD, low-level ppm HF OPGD for (IR) gas detectors on the market. A lenses are entirely blocked, thereby refinery alkylation processes, percent low-temperature version allows op- reducing downtime. The Model IR700 LEL HVAC OPGD cross-duct methane eration down to –50°C for the harsh- IR detector features microprocessor- detection, and percent LEL cross-duct est industrial environment. The mean based technology to continuously continuous methane monitoring for time between failures (MTBF) and monitor CO2. It features multiple coal-bed combustion. — Senscient, Inc., the probability of failures on demand communication outputs, a 4–20-mA League City, Tex. (PDF) both calculated by INERIS are signal, proportional to 0–100% full- www.senscient.com respectively 28 years and 1,6 ฀10–3 scale, Modbus and HART. — General with a one-year interval test. — Old- Monitors, Lake Forest, Calif. Detect oxygen defi ciency with- ham Gas, Pittsburgh, Pa. www.generalmonitors.com out high maintenance burdens www.oldhamgas.com The 4501-03, Oxygen Deficiency Gas Wireless communication im- Detector (photo) is a two-wire, loop- CO2 detector protects proves installation and trending powered gas detector that boasts lower against dangerous leaks Said to be an industry first, ELDS cost and easier installation and main- Offering reliable gas detection per- Version 1.2 Open Path Gas Detectors tenance. This eliminates the need for formance with low maintenance, the (OPGDs) feature Integrated 2.4 GHz separate power runs and associated rugged Model IR700 Carbon Dioxide Wireless Communications between the power distribution and circuit protec- Point Detector (photo) requires no ELDS Transmitters/Receivers and the tion for each device. Meanwhile, main- routine calibration and provides com- vendor’s installation and commission- tenance costs are low due to 4–20-mA, plete control room status and control ing tools. The ELDS is easy to install, two-wire loop-powered design, a six- capability for monitoring 0–5,000 with 2.4 GHz wireless alignment and month calibration interval and the ppm. The Model IR700 features a pre- access to event logs, self check results, ability to calibrate without declassify- cision IR point-sensing element that and system diagnostics. This eliminates ing the area. — Sierra Monitor Corp., offers reliable protection against the hard-wired Class I Division I or II con- Milpitas, Calif. hazards of carbon-dioxide gas leaks. nectors and cables, or area de-classifi- www.sierramonitor.com ■ While CO2 is nonflammable, exposure cation for technician access to detectors Rebekkah Marshall 24 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Emerson Process Management

Siemens Let this company collect and analyze machinery vibration data This condition-monitoring specialist company has introduced a vibration data collection-and-analysis service (photo) for industrial plant operators that aims to minimize downtime and maximize productivity. Where no fixed machine condition-monitoring system is available (or is impractical) for criti- cal plant, this company recommends that periodic vibration data collection should be implemented to monitor and trend the op- erational condition of ma- chinery. Offline analysis by the company’s vibration experts can then identify faults and impending fail- ures that enable schedul- ing of maintenance. No upfront capital investment is required to add regular monitoring of all a compa- ny’s machinery and plant equipment. — Sensonics Ltd., Berkhamsted, U.K. Pointwise www.sensonics.co.uk

Power supplies with large current outputs Sensonics The Sitop smart family (photo) has been extended with three single-phase, 24-V power supplies with rated output currents of 2.5, 5 and 10 A, as well as two 12-V power supplies with 7- and 14- A outputs. The output voltage of the new PSU100S power sup- ply (photo) is adjustable over the range of 24 to 28 V for the 24-V versions, and up to 15.5 V for the 12-V models. All devices can supply 1.5 times the rated current for 5 s/min to ensure problem- Gridgen V15.18 is said to increase other features. — Pointwise, Inc., free starting for all loads that draw the recovery of prism cells from the Fort Worth, Tex. a high current. — Siemens Industry layers of extruded tetrahedra in the www.pointwise.com Sector, Erlangen, Germany boundary layer. It offers the option www.siemens.com/sitop to use a Green-Gauss formulation This wireless vibration transmit- for computing prism volume that is ter now has ATEX approval New features offered in “more forgiving” than the default for- With ATEX Zone 0 and Class I, Div. 1 this latest CFD software mulation, and includes two improve- ratings, the CSI 9420 Wireless Vibra- Last month saw the release of V15.18, ments to the algorithm’s ability to tion Transmitter (photo) can now be the latest version of Gridgen soft- smoothly extrude more tetrahedral installed directly in hazardous areas, ware for computational fluid dynam- layers from concave regions. V15.18 such as chemical, petrochemical and ics (CFD) mesh generation (photo). also includes several “bug” fixes and offshore facilities, as well as other ex-

Note : For more information, circle the 3-digit number CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 24I-1 on p. 60, or use the website designation. Michell Instruments New Products

plosion-classified environments. The safety ratings, which are in addition to existing hazardous-area ratings to the IECEx and Brazilian standards, further extends the benefit of wireless technology to new areas of the plant. The CSI 9420 connects quickly, easily and economically to any machine, and provides key insights to the condition of pumps, fans and other assets located in hazardous areas, without the expense of running cables. — Emerson Process Management, Baar, Switzerland www.emersonprocess.com

A safety relay that is certified for SIL 2 The Safety Relay Module (SRM; photo) is said to be a versatile relay re- peater module that has been certified by Exida for single use in safety-in- strumented systems (SIS) up to SIL 2. The SRM is part of the company’s FS Functional Safety Series and accepts single-contact closure in- puts from logic-solver trip outputs, including the STA Safety Trip Alarm and the SPA2 Programmable Limit Alarm Trip. With three contacts per alarm input, the SRM allows for the addition of alarm contacts to safety processes without special installation or configuration. — Moore Industries International, Inc., North Hills, Calif. www.miinet.com Moore Industries Omega International Engineering Measure soil dampness with one hand Analyzer (photo), making it approved A Web-based application for The new HSM50 Series of digital for use in hazardous areas in the U.S. generating valve assemblies handheld moisture meters (photo) is and Canada. The instrument already The new RapidDraw3D Valve-model easy to operate, and enclosed in a com- carries certification from ATEX and Generator is a free automated valve- pact ABS-plastic housing for measur- IEC Ex. The XTP601 uses thermo- assembly model generator that al- ing moisture in soil or similar mate- paramagnetic measurement technol- lows users to quickly generate real- rial. The microprocessor-based device ogy to make accurate and stable mea- istic, to-scale three dimensional (3D) displays data quickly and accurately surement of O2 in background gases, valve assemblies and export them to on an LCD screen. The unit has a such as H2, N2 and CO2, over ranges any CAD program for use in plant measurement range of 0 to 50% mois- from 0–1% and 0–25%. Housed in a piping diagrams. RapidDraw3D is ture content with an accuracy of ±5% flame- and explosion-proof enclosure, said to be easy to use, and can be of full scale, and operates over a tem- the instrument is available in three accessed for free upon registering perature range of 0 to 50°C. — Omega versions: a blind transmitter, a unit at www.rapiddraw3d.com. The 3D Engineering, Inc., Stamford, Conn. with status LEDs or a full-display unit. rendering can be downloaded from www.omega.com All three versions are supplied with the Internet for import to the chosen two 4–20-mA outputs, two concentra- CAD program, such as PDF, Auto- This O2 analyzer is certified for tion alarms, Modbus RTU over RS485 CAD, SolidWorks, DXF, STEP IGES hazardous areas protocol and application software. — Parasolids and more. — Metso Auto- This company has attained CCSAUS Michell Instruments, Ely, U.K. mation Inc., Helsinki, Finland certification for its XTP601 Oxygen www.michell.com www.metso.com

24I-2 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Pumps ■ Valves ■ Systems

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Circle 11 on p. 60 or go to adlinks.che.com/40272-11 Yokogawa Mettler Toledo AutoChem

New Products

Clamp on this process meter to measure currents Launched last month, the CL420 Clamp-on Process Meter (photo) mea- sures 0–120-mA d.c. process-control signals without breaking the loop. Typical applications include distrib- uted control systems, programmable logic controllers, pressure and temper- ature transmitters and loop-powered isolators and indicators. The device offers a 0.2% accuracy and 0.01-mA resolution from 0 to 20 mA d.c. Other features include milliampere measure- ment and percent-of-span for 4–20- mA, dual LCD numeric display, LED Syrris torch light and data-hold function and a 6-mm-dia. clamp. An analog output is also available. — Yokogawa Corp. of America, Newnan, Ga. www.yokogawa.com/us

A high-pressure reactor system for process development The EM20-100-HC and EM60-100-HC 100-mL Hastelloy Pressure Reactors (photo) are designed for use with this company’s EasyMax synthesis work- station. These reactors expand the use of EasyMax to both autoclave-like organic synthesis and high-pressure process characterization. The 100-mL reactor’s design enables quick setup and fast results from low- to medium- pressure reactions (to 100 bars) using the built-in touch-screen and reactor combination like an autoclave; this simplifies mixing, temperature and pressure control and allows measure- ment of mass flow and gas uptake. commercially available, laboratory- intense sunlight or brightly lighted Accessories, such as the iControl soft- scale flow aqueous extraction system, indoor conditions. All lights use ad- ware, enable evaluation of gas con- and can be used with a wide variety of vanced LED technology to provide lon- sumption, mass transfer, kinetics and organic solvents that are either more or ger life and lower energy consumption heterogeneous catalysis. The reactor less dense than water. Membrane tech- than fluorescent or incadescent light covers the temperature range between nology enables separation of the wid- sources. Custom capabilities include 20 and 180°C. — Mettler Toledo Au- est possible range of phase mixtures, lights with five color combinations toChem, Inc., Greifensee, Switzerland including tetrahydrofuran (THF) from selectable from nine different colors. www.mt.com/easymax aqueous phase, and controls bubble — Hans Turck GmbH & Co. KG, Mül- formation, thereby limiting the forma- heim an der Ruhr, Germany Continuous L-L extraction — tion of emulsions that commonly occur www.turck.com no shaking required using traditional liquid-liquid extrac- The Asia FLLEX (flow liquid-liquid ex- tions. — Syrris, Royston, U.K. This extruder cooks ingredients traction) module (photo) is a flow chem- www.syrris.com and makes a healthy snack istry equivalent to a separating funnel, The ZSK MEGAvolume Plus twin- yet involves no shaking, nor does it rely Lights that can be seen even screw extruder, featuring 54-mm-dia. on gravity. It is suitable for the prepa- when it’s already bright out screws, has been custom made by this ration of samples prior to analysis, Five new EZ-Light high-intensity company for a new production line for further synthetic steps or purification. indicators have been introduced to the food industry that was recently The Asia FLLEX is said to be the only provide clear, long-range visibility in commercialized by Dinnissen B.V. (Sev-

24I-4 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Allison Engineering

SYSTEM ANALYSIS

This analyzer optimizes biogas Our experts analyse your system and yields, minimizes H S formation show where you can save energy – 2 with SES System Ef ciency Services Designed and manufactured in Ger- or PumpMeter. many, the Awi-Flex multifunctional biogas analyzer (photo) is sup- plied with a small air compressor that regu- lates air injection into the digester (above the sludge level) to SELECTION between 0.5 and 1 vol.% for breaking Your KSB partner or KSB EasySelect will help you nd exactly the right down H2S into elemen- pumps and valves. tal sulfur and water. By accurately measuring the O2 and H2S levels in the biogas and using a combination of PI and fuzzy logic control, H2S levels can be reduced by up to 80%, says the company. The Awi-Flex analyzer is HIGH-EFFICIENCY designed to measure CH4, CO2, H2S, HYDRAULIC COMPONENTS O2 and H2, with up to five measuring Top pump and valve performance Coperion points. It features an integral PC that with minimum loss – all thanks to enables easy access to recorded data, 140 years of innovation and expertise. enum, The Netherlands). Tradenamed sensor parameters and system diag- Magi-N.ext (photo), the new production nostics, with 4–20-mA, Profibus and line permits the production of a wide Ethernet communications. — Allison range of preserved and healthy conve- Engineering, Basildon, U.K. nience foods. The starch components www.allison.co.uk of different recipes are gelatinized by HIGH-EFFICIENCY means of an extrusion cooking process Separate components from gases DRIVES in which the shearing action of the with this desublimator Our high-ef ciency motors even twin screws rapidly causes the temper- The Pluto mini-desublimator is used exceed today’s standards. ature of the mixture to rise to 100°C. to separate substances in applications In conjuction with the water from the such as for tank breathing, thereby content in the product, the native raw reducing emissions to the environ- starch is gelatinized. A degassing step ment, for recovering raw materials removes a large portion of the moisture or for protection of downstream vac- via a vacuum system, creating directly uum generators. Gas comes in con- expanded, easily manageable products tact with cooled lamellae in the Pluto DEMAND-DRIVEN obtained at the pelletizing stage by a unit; here, the gas component to be OPERATION centric pelletizer, ZGF 70. — Coperion separated desublimates at or below Optimised control systems like GmbH, Stuttgart, Germany its triple point and adheres to the PumpDrive continuously match www.coperion.com cold surface in crystalline form. The pump output to system requirements.

www.ksb.com/fl uidfuture Circle 12 on p. 60 or go to adlinks.che.com/40272-12 New Products

GIG Karasek Pluto unit is split into several sectors A smart fl ange system for to prevent deposits from clogging the increased safety gas inlet. As soon as the desublimator The QVF Supra-Line is com- is loaded, the solid product is melted patible with two proven flange off. Separation efficiencies of over systems — the QVF/WPR2002 95% are achieved, says the manufac- and the Schott/KF systems — turer. The Pluto unit can be supplied and thus reduces the number in all weldable materials, and can be of technically equivalent com- used across the temperature range ponents required while provid- from –20 to 350°C, as well as within a ing the user with increased pressure range between vacuum and safety. The Supra-Line ex- 10 bars. — GEA Luftkühler GmbH, tends the allowable operating Bochum, Germany conditions for temperatures up www.gea.com to 200°C, provides extensive resistance to acids and sol- Software simulates vibrations to vents, and an even higher keep machinery healthy corrosion resistance In order to detect unexpected torsional due to its fire-pol- and lateral vibrations in mechanical ished flanges. The drive systems, computer simulation Supra-Line flanges is crucial to determine the dynamic in the nominal behavior of rotating machinery. This size range from DN company offers a new, re- vised software package the heated and cooled panels lead to simulate both torsional to a high evaporation and conden- and lateral vibrations while sation surface in the smallest pos- also considering nonlinear sible space. As a result, the econom- characteristics (such as high- ics are more favorable when using elastic coupling elements, gear the Plate Molecular Still compared couplings and backlash in gear ARLA to more expensive short-path distil- stages), steady state and also time- Maschinentechnik lation processors, says the company. transient conditions. A software pack- — GIG Karasek GmbH, Gloggnitz, age for a comprehensive rotordynamic Austria analysis, including fluid-film bearings 15 to 300 require only one seal per www.gigkarasek.at (photo), is also available and inte- nominal diameter, regardless of the grated into the rotordynamic analysis shape of the flange. The flange con- Level control is simplifi ed with simulation system ARMD 5.7 G2. — nection features a patented clamp- non-steady-state tuning ARLA Maschinentechnik GmbH, Wip- ing system with a ringed grounding This company’s software now in- perfuerth, Germany element within the groove of the cludes non-steady-state (NSS) mod- www.arla.de flange instead of screwed-on lugs. — eling features for integrating control De Dietrich Process Systems GmbH, loops. These tools are said to provide Gas cylinder storage simplifi ed Mainz, Germany fast, simple modeling and tuning of with Website Wizard www.qvf.de level controls. Unlike temperature, This company’s updated Website now pressure and flow, level controls features a Gas Cage Wizard that An economical way to distill have different dynamics, and these makes choosing the right gas cylinder large volumes of products new tools make it simple to tune storage option simpler. Users enter The patented Plate Molecular Still level controls, even while the level the height, diameter and the number (photo) is capable of distilling large is moving, says the company. NSS of cylinders that need to be stored, and quantities of product (10 ton/h and tuning integrates seamlessly with the Wizard instantly calculates and more), under medium- or high- the company’s PlantTriage and PID suggests the most suitably sized cage vacuum conditions. The system is Loop Optimizer software. These tools from a standard range of cages. In ad- suitable for applications involving also provide capabilities for both dition to a wide range of mesh cages, temperature-sensitive substances, tight control and surge-tank scenar- enclosures and cabinets, the Website such as oils, fats, pharmaceuticals, ios. NSS modeling is included with also provides essential, up-to-date vitamins, methyl esters and more. PlantTriage Version 11 and higher, U.K. Health and Safety Executive The product is fed through a distri- and with PID Loop Optimizer Ver- (HSE) information and FAQs. — Gas bution system to the outer surface of sion 21 and higher. — ExperTune Cage Direct, Crawley, U.K. the evaporator plates within a cylin- Inc., Hartland, Wisc. www.gascagedirect.co.uk drical vessel. In this arrangement, www.expertune.com

24I-6 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 M 957-E4.QXD_Chem_Engineering 10.06.11 09:18 Seite 1

Freudenberg Filtration Technologies clouds. These pipe solids can be automatically connected THE CHEMICAL DIVISION into pipe runs, annotated with EdgeWise MEP, and then brought directly into Revit as fully functional Revit pipe FILLING VISIONS objects. All data, such as di- ameter, length, elbow bend ra- dius and more, are also trans- ferred into Revit. Beta testers report modeling-time savings of up to 85% over previous workflows, says the company. Future releases will handle Herbold Meckesheim square ducting, cable trays and other planar objects. — ClearEdge3D, Herndon, Va. www.clearedge3d.com

Efficient filter cartridges that require no precoating Installed into Viledon sinTexx filter cartridges, this new cor- rugated polyester medium with nanofiber lining (photo) is said to achieve optimum performance when dealing with fine and difficult-to- handle dust and smoke. Com- Granulate and recycle plastics pared to conventional corrugated poly- TURNKEY VISIONS waste for less energy ester materials and ePTFE (expanded Among the products being exhibited at polytetrafluoroethylene) membranes, the Fakuma Plastics Recycling Trade the Viledon sinTexx media with nano- n process technologies Show (Friedrichshafen, Germany; Oc- fiber lining offers several advantages, tober 16–20) is the Granulator SML says the manufacturer: Higher collec- which are free of interfaces: 45/60 SB (photo) with forced feeding tion efficiency, even during initial op- (patent pending). This unit has a spe- eration; lower flow resistance, which stocking – mixing – filling cial granulator design that can consid- reduces power and compressed-air erably reduce its energy demand, with consumption and extends their use- a 30 to 50% lower connected load com- ful lifetime; and customary precoat- n complete turnkey plants pared to a traditional machine. Pre- ing is not required. — Freudenberg shredded waste and hollow bodies can Filtration Technologies SE & Co. KG, from the thus be recycled in a very economic Weinheim, Germany way. — Herbold Meckesheim GmbH, www.freudenberg-filter.com HAVER & BOECKER group: Meckesheim, Germany www.herbold.com No membranes required for this engineering – delivery – dissolved oxygen sensor service New piping software slashes The new 2610 Optical Dissolved Oxy- time for modeling workflows gen Sensor utilizes optical technology With the new release, EdgeWise MEP to measure dissolved oxygen with for Autodesk Revit, users can now, high repeatability and accuracy while for the first time, bring extracted reducing maintenance and energy pipes, conduits and other cylindrical costs, says the company. This device HAVER & BOECKER, Germany mechanical, electrical and plumbing eliminates the need for replacement Phone: +49 2522 30-271 (MEP) elements directly into Revit. membranes and reference solutions Fax: +49 2522 30-403 This new MEP software leverages the associated with traditional galvanic E-mail: [email protected] powerful feature-extraction technol- or polarimetric measurement tech- ogy of EdgeWise to automatically ex- nologies, and therefore has reduced www.haverboecker.com tract pipe solids from laser scan-point maintenance costs. The 2610 has M 957-E4 Circle 9 on p. 60 or go to adlinks.che.com/40272-09 The Jet Pulverizer

Flottweg New Products

an optical cap sensor that is factory calibrated — no field calibration is necessary — and built-in ModBus RS485 and 4–20-mA current-loop out- puts. The sensor can be com- bined with the new 9900 transmitter, and covers the range from 0 to 20 mg/L, 0–200% saturation with accuracies of ±0.1 mg/L (for 0–8 mg/L) or ±0.2 mg/L (for 8–22 mg/L). — GF Piping Systems, Tus- tin, Calif. Smith & Loveless www.gfpiping.com and are easily accessible. Special at- skid-mounted package. Each system Process more beer with this tention was given to the new design is preassembled and shipped directly larger clarifi er of the cutter head in order to ensure to the job site on one truck, thereby To be introduced next month at Brau the production of evenly shaped, high- significantly reducing field installa- Beviale 2012 (Nuremberg, Germany; quality pellets, says the manufacturer. tion costs while allowing for a compact November 13–15), the AC2500 beer — Maag, Oberglatt, Switzerland footprint. All components are con- clarifier (photo) processes up to 600 www.maag.com structed of stainless steel and utilize hL/h of beer, making it suitable for big patented technologies, including grit- breweries. The AC2500 can be used This large-capacity mill has removal technologies with V-Force flexibly for pre-clarification before fil- design features of smaller ones Baffel, S&L Pista Turbo Grit Pump tration, green-beer clarification and The new 36-in. Orbital Bottom Side and the Grit Washer featuring Tri- for turbidity adjustment in the case of Feed Mill (photo) is designed to pro- Cleanse Technology. The system comes cloudy beer, such as wheat beer. Like cess 3,000–6,000-lb/h capacities, and with a PLC-based control system with its smaller predecessors, the AC2500 combines design features normally touch-screen, color human machine in- features the SoftShot bowl discharge found only in smaller mills, says the terface (HMI) and NEMA 4X panel to system, in which yeast is separated manufacturer. The combination of operate the entire system. Pista Works from beer and collected in the solids the bottom side feed and orbital-mill operates peak system flow capacity chamber of the bowl. The system auto- design elements is said to offer best- of 0.5–7-million gal/d, depending on matically recognizes, by turbidity mon- in-class performance, efficiency and the model. — Smith & Loveless, Inc., itoring, when the bowl is completely durability. The orbital distribution Lenexa, Kan. full. The feed system, valves and dis- chamber offers multiple injection www.smithandloveless.com charge system have been optimized to points, ensuring even distribution of minimize the impact of shear forces. — material into the grinding chamber, This concentrate pump operates Flottweg SE, Vilsbiburg, Germany which results in tighter product dis- with steam, air or more www.flottweg.com tribution and higher processing rates. The new Pivotrol PTF4 is a high-capac- The bottom side-feed modifications ity, pressure-powered condensate pump A pelletizing system for allow for greater process clarification that covers a wider motive-pressure smaller-scale production of product, while reducing wear on the range. This new version can be oper- With a production flowrate of up to mill. Traditional C-clamps have been ated by steam, air or other pressurized 600 kg/h, the Sphero 50 underwater replaced with bolts to add rigidity, flat gases, and covers a complete pressure pelletizing system can be applied in seals have been replaced by O-rings range of up to 200 psig. The PTF4 incor- testing plants and smaller produc- for tighter sealing, and a new feed- porates dual Pivotrol pumping mecha- tion plants with pelletizing options injector nozzle design allows for easy nisms with PowerPivotol technology, for virgin polymers, masterbatches, adjustments during processing. — The and is backed by a 3-million cycles or compounds, recycling, organic and Jet Pulverizer Co., Moorestown, N.J. five-year extended warranty, which is wood-based polymers, and more. The www.jetpulverizer.com available as an option. Patented vent- entire system is mounted on a mobile assist valves release pressure in the frame with lockable wheels, and can Four headworks processes pump during the exhaust stroke, for be easily moved and adapted to dif- preassembled into one package faster filling or overall cycling, leading ferent extruders. All components, such The complete Pista Works headworks to higher capacities. — Spirax Sacro, as startup valves, die plates, water system (photo) combines several head- Blythewood, S.C. basins and drives are suspended from works processes — screening, grit re- www.spirax.com ■ a T-bar, can be shifted horizontally moval and grit washing — into one Gerald Ondrey

24I-8 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Fans and Blowers

Department Editor: Scott Jenkins

ans and blowers are com- contractions and interferences at A. Fan and system matched B. Wrong fan mon in air-handling and F fan inlets and outlets. Fan System System movement systems used in the chemical process industries Fan efficiency Fan Desired Desired (CPI). Two major uses of fans The denominator of the power and blowers are in pneu- Actual equation includes a factor to (P) Pressure (P) Pressure matic conveying systems and reconcile the units with fan effi- in ventilation and air-pollution- ciency. Efficiency affects power control systems. Powering fans inversely. However, there are Flowrate (Q) Flowrate (Q) and blowers can contribute limits on what fans can deliver. C. Wrong system D. Wrong fan and system significantly to costs, and their The design of a fan and its Fan efficient operation can be blade type can greatly influence Fan System affected by the way plant opera- efficiency. Meanwhile, the fan’s Desired System tors select and run their systems. peak point of efficiency mea- Desired Actual Included here are considerations sured in a laboratory may not Actual Pressure (P) Pressure Pressure (P) Pressure for selecting and operating fans necessarily be the most stable and blowers in dilute-phase point of operation. If peak ef- pneumatic conveying and air- ficiency coincides with the peak Flowrate (Q) Flowrate (Q) pollution control applications. of the pressure curve, then there FIGURE 1. Both the fan and system curves must be considered may be operational problems, when choosing the best fan and operating point to optimize reliability Air pollution control as volumetric flowrates vary and power use Air-pollution control systems with only tiny changes in system Gas delivery must protect plant workers from pressure. The designer must the process, while also meeting consider both curves when all emissions standards set forth choosing the best fan and in local and national regula- operating point to optimize reli- tions. The system should also ability and power usage. seek to minimize energy costs A fan’s peak point of ef- Gas intake as well as replacement costs ficiency may not be the most FIGURE 2. (such as filter bags and neutral- Air trapped between the rotors and blower housing is stable point of operation. Both transferred from inlet to outlet without compression izing chemicals). the fan and system curves must The power required for an be considered when choosing volume delivered. the discharge pressure. Com- air handling system is computed the best fan and operating A fan’s volumetric output pression ratio for these blowers using the following factors: point to optimize reliability and depends on its discharge is about 2 to 1, which means Volumetric flowrate (Q) in ft3/ power usage (Figure 1). pressure. The output of the that if the inlet air is atmospheric min; total pressure (in. H2O); re- System pressure is affected fan decreases as the pressure pressure (14.7 psia), the blower sistance due to friction in ducts, by hood and duct resistance as increases, and increases as the can handle discharge pressures hoods and ∆P of control device; a function of velocities in the pressure decreases (an inverse up to two times atmospheric density factor of the gas being system and the inefficiencies of relationship). Fans’ output air pressure, or about 15 psig. collected (df), dimensionless; flow (fan-system effects). volume changes with a change Capacity is directly related to and efficiency of the fan (η), in discharge pressure. blower speed, and has an upper dimensionless. The air power Pneumatic conveying The best application of fans limit because of the maximum equation is the following: Dilute-phase pneumatic is a system in which conveying allowable tip speed of the timing ()QT()Pd()f conveying systems generally conditions (such as conveying gears (~4,500 ft/min). Powerh()p = rate, distance and material To optimize the performance ()η (,6 356) use centrifugal fans and posi- (1) tive displacement blowers for type) are relatively constant of blowers in pneumatic convey- Any increases in flow, system to- supplying conveying air to the parameters, and the resulting ing systems, consider the follow- tal pressure, or density will raise system. Compressors are used conveying system pressure is ing points: power requirements. Increases in for dense-phase, high-pressure not expected to change much. • Blowers should be oil-free fan efficiency will reduce power pneumatic conveying. For fans, airflow reductions • Blowers should be operated requirements. A system handling Two key factors for pneumatic correspond to air pressure at the middle of equipment twice as much air will require conveying systems are airflow increases, and airflow stops operating range twice the power to control and air delivery pressure. The when the conveying line plugs. • Blower speed should be emissions if all other factors are relationship between the two Horsepower decreases as air 1,800 rpm equal. Twice the volumetric air- dictates the selection of an air pressure increases. Fans are • Volumetric eficiency should flow also requires larger ducts, mover for these systems. used mostly in applications that be high control devices and fans. Fans. Fans are usually used in require high air volume at low • Mechanical eficiency of the Careful manipulation of the low-pressure conveying systems pressures. The main advantages drive should be as high as factors in the equation, including where the pressures are less of fans are their low cost, low possible fan efficiency, can have cost- than 2 psig, or where both large noise levels and avoidance of • The pressure drop for the inlet saving effects throughout the air flows and low pressures are the need for close clearances. filter should be as small as system’s life. However, reaching required. Fans used in these Blowers. Blowers for dilute- possible situations are usually of the cen- phase pneumatic conveying the desired flowrate and pres- Editor’s note: trifugal type, rather than axial. systems are generally rotary, The content for this edi- sure requires that fan-system ef- tion of “Facts at your Fingertips” was fects be considered. Inefficiency The main disadvantage of positive displacement, lobe-type adapted from the following sources: due to these fan-system effects fans is their relatively steep- blowers (Figure 2). Lanham, G. “Energy Efficiency: Opti- sloping performance curve, These blowers are consid- mizing the Air-Power Equation.” Chem. could result because of poorly Eng., June 1, 2007, pp. 50–53; and designed hoods, short-radius wherein even a small change ered positive displacement type Agarwal, A. “Moving Air in Pneumatic elbows, branch-entry angles in discharge pressure results in because they deliver a constant Conveying Systems, Chem. Eng., Sept. of more than 45 deg, abrupt a significant change in the air volumetric airflow regardless of 2011, pp. 38–42. FeatureCover Story Report Acids Handling General guidelines Acid vapor pressure versus temperature on materials, storage, 100.00 pumping and other

concerns for the 10.00 proper and safe handling of acids

1.00 Alberto Baumeister Sebastiano Giardinella Mayhell Coronado bar pressure, Vapor Ecotek 0.10 norganic acids play a major role in the chemical process industries (CPI). They are used as raw ma- Iterials, catalysts or finishing and pH control agents in the manufacture 0.01 of a wide range of chemical products, -150 -50 50 150 250 350 Temperature, °C from fertilizers to detergents, and even foods. Given their widespread HCl (pure) HNO3 (100 wt.%) H2SO4 (70 wt.%) H2SO4 (100 wt.%) use, a major issue in the CPI is the HF (pure) HNO3 (90 wt.%) H2SO4 (80 wt.%) H2SO4 (98 wt.%) proper and safe handling of the acids, HCl (34 wt.%) HNO3 (70 wt.%) the adequate materials selection for the pieces of equipment, piping and fittings used in the process, and the FIGURE 1. The vapor pressure as a function of temperature for the acids covered in correct storage and even disposal of this article these materials. These are important factors that Physical properties cal properties of the acids covered in need to be taken into account from the Some acids are naturally present as this article are briefly presented here. design phase throughout the operat- liquids (H2SO4), some are solids at am- These properties for common avail- ing life of a facility, in order to ensure bient conditions (anhydrous H3PO4), able grades are presented in Table 1. there will not be integrity problems and others are gases (HCl, HF). Acids Figure 1 plots their vapor pressures that may negatively impact project are very soluble in water and thus also at different temperatures. economical turnover, personnel safety widely available as aqueous solutions Sulfuric acid. Sulfuric acid is the or the environment. at different concentrations. Some of single most important inorganic This article covers the most im- these solutions are also enhanced by chemical in tonnage produced and in portant inorganic acids: sulfuric acid dissolving additional compounds (for use. H2SO4, can be described as a col- (H2SO4), nitric acid (HNO3), phos- example, fuming sulfuric acid is made orless, oily, hygroscopic liquid with no phoric acid (H3PO4), hydrogen chloride by dissolving SO3 in sulfuric acid). odor; it is the largest inorganic chemi- (HCl) and hydrochloric acid, and hydro- Given that there are several avail- cal manufactured and one of the most gen fluoride (HF) and hydrofluoric acid; able grades, the knowledge of physi- widely used inorganic chemical in the providing general guidelines on their cal properties for each one is impor- manufacture of many other products. physical properties, safety data, ap- tant in order to avoid freezing, the By the year 2004, North America and propriate materials, storage, pumping formation of hazardous fumes, or Asia were the biggest producers of and other common issues encountered other problems when storing and sulfuric acid, recording almost 60% of when handling such fluids in the CPI. handling these materials. The physi- world total production. Sulfuric acid

26 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 TABLE 1. PHYSICAL AND CHEMICAL PROPERTIES OF ACIDS [1–5]

Units H2SO4 H3PO4 HNO3 HF HCl 7664- CAS Number 7664-93-9 7697-37-2 7664-39-3 7647-01-0 38-7

Molecular g/gmol 98.079 97.994 63.01 20.01 36.46 weight Aqueous. Fuming, Concen- Gas (an- Gas (an- Technical Grade Fertilizer Tower 65% Pure WFNA Strong Common Aqueous Aqueous Aqueous trated hydrous) hydrous) Grade oleum 22°Be Concentra- 35 H SO , wt.% 98 78–80 62–70 2 4 75–85 100 90 68 100 48–51 40 100 50 33 tion 65 SO3 Physical Liquid Liquid Liquid Liquid Solid Liquid Liquid Liquid Gas Liquid Liquid Gas Liquid Liquid state Color Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Colorless Disagree- Pungent Pungent able (can Pungent Acrid Pungent Pungent Pungent Odor Odorless Odorless Odorless Odorless Odorless Acrid odor odor odor cause odor Odor odor odor odor choking) Boiling point °C 340 200 155.85 151.1 212.8 86 120.5 121 20 108 112.2F –85 100 83 (760 mmHg) Vapor density 3.4 3.4 2.2 2.5D 0.7 1.97 1.3 0.62 1.267 (air = 1) Specific grav- 1.83 1.72 1.57 1.56 1.87 1.50 1.50 1.50 1.17 1.14 1.03 1.16 ity (H2O=1) Liquid B C A density (at g/mL 1.8361 1.7272 1.6105 1.5533 1.579 1.5129 1.4826 1.4048 1.202 1.159 1.251 1.164 20ºC) Melting point °C 10.5 –4.29 –36.55 –36.98 42.2 –42 –41.6 –83 –40 –62 –114 –46.2 Dynamic viscosity (at cP 20.5 6.5 3.52 2.68E 2 20ºC) Notes: A Liquid Density of phosphoric acid at 75% B Liquid density of sulfuric acid at 80% C Liquid density of sulfuric acid at 70% D Vapor density of nitric acid at 65% E Dynamic viscosity obtained after extrapolation F Boiling point at 38.2% is manufactured by the combustion of acts violently in the presence of strong als to form explosive hydrogen gas. Its sulfur with dry air to form sulfur diox- bases, reducing agents and combusti- appearance varies from pale yellow to ide (SO2), then sulfur trioxide (SO3) is ble fluids, such as turpentine, charcoal colorless, according to purity. produced through a catalytic conver- and alcohol. It is corrosive to metals, Hydrochloric acid has many appli- sion. Finally, sulfuric acid is obtained forming flammable or explosive gas. cations in the production of organic after absorption of SO3 in water. Nitric acid also reacts violently with and inorganic compounds such as fer- Sulfuric acid is a strong acid and a organic compounds. tilizers, chlorides, dyes and more. HCl strong oxidizing agent; therefore it re- Phosphoric acid. H3PO4 or or- plays an important role in pickling acts violently with bases, combustible, thophosphoric acid is a white solid of steel, acid treatment of oil wells, reducing materials, water and organic with a melting point of 42°C, which is chemical cleaning and processing, and compounds with the evolution of heat. highly soluble in water, non-toxic and ore reduction among others. It is highly corrosive to most common a relatively weak acid. When boiling all aqueous solutions, metals and forms a flammable/explo- H3PO4 is the third most important HCl forms an azeotropic constant- sive gas. acid in industry. It is used mostly in boiling mixture that contains 20.24% Sulfuric acid is mostly used in the the production of phosphate fertiliz- HCl and boils at 110°C (230°F). manufacturing of fertilizers, organic ers; but also in the manufacturing of Hydrogen fluoride and hydroflu- pigments, explosives and more. As a agricultural feeds, soaps, detergents, ric acid. Anhydrous hydrogen fluo- strong electrolyte it is used in electro- waxes; and in the food industry as pre- ride (AHF) is a clear, colorless, corro- plating baths for pickling, and for op- servative, acidifier, clarifier or flavor sive fuming liquid with an extremely erations in the production of iron and enhancer; among other uses. sharp odor. It easily dissolves in water steel. Moreover, it is extensively used H3PO4 has two main methods of pro- to form hydrofluoric acid. as a solvent for ores and as a catalyst duction: the wet process and electric HF forms dense white vapor clouds in the petroleum industry. furnace. It is commercially available if released. Both liquid and vapor can Nitric acid. HNO3 is a solution of ni- at concentrations of 75, 80, 85 and 87 cause severe burns to all parts of the trogen dioxide (NO2) in water; it is a wt.% of PO3. Higher concentrations, body. Specialized medical treatment is colorless to light-brown fuming liquid such as 105 wt.% (superphosphoric) required for all exposures. with an acrid suffocating odor. Nitric and 115 to 118 wt.% (polyphosphoric) HF occurs naturally in volcanic acid is the second most important in- are also available. “Pure” or “techni- gases and may result from industrial dustrial acid; it is a highly oxidizing cal grade” phosphoric acid is usually activities, such as coal-burning, and agent, used in the manufacture of found at 85 wt.%. the manufacture or production of alu- chemicals, explosives, fertilizers, steel Hydrogen chloride and hydrochlo- minum, phosphate fertilizer, steel and pickling and metal cleaning. However, ric acid. Hydrochloric acid is a solu- other chemical derivatives. the largest use for nitric acid is for the tion of the gas hydrogen chloride; it is Commercially, HF is used to man- production of fertilizers. a poisonous, highly corrosive, hazard- ufacture fluoropolymers, pharma- Nitric acid is a strong acid that re- ous liquid that reacts with most met- ceuticals, aluminum, stainless steel,

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 27 Cover Story

TABLE 2. TOXICITY AND EMERGENCY RESPONSE DATA

H2SO4 H3PO4 HNO3 HF HCl PEL (OSHA) 1 mg/m3 1 mg/m3 TWA 2 ppm, 3 ppm, 2 mg/m3 TWA 5 ppm, 7 mg/m3 ceiling [6–8] 5 mg/m3 TWA

REL (NIOSH) 1 mg/m3 TWA 1 mg/m3 TWA; 2 ppm, 3 ppm, 2.5 mg/m3 TWA; 5 ppm, 7 mg/m3 ceiling [9] 3 mg/m3 STEL 5 mg/m3 TWA; 6 ppm, 5 mg/m3 (15 min) 4 ppm, ceiling 10 mg/m3 STEL IDLH 15 mg/m3 1,000 mg/m3 25 ppm 30 ppm 50 ppm (NIOSH) [9]

Incompat- Organic materials, chlorates, carbides, fulminates, Strong caustics, most Combustible materi- Metals, water or steam. Cor- Hydroxides, amines, alkalis, ibilities & water, powdered metals. Reacts with water to produce metals, Reacts with als, metallic powders, rosive to metals. Attacks glass copper, brass, zinc. Hydrochlo- Reactivities heat. Corrosive to metals metals to form H2 hydrogen sulfide, car- and concrete ric acid is highly corrosive to gas. Do not mix with bides, alcohol. Reacts most metals solutions containing with water to produce bleach or ammonia heat. Corrosive to metals UN Listing 1830: sulfuric acid; sulfuric acid, 2796: sulfuric 1805: phosphoric 2031: nitric acid, 1052: hydro- 1790: hydro- 1050: hydrogen 1789: hy- Number with more than 51% acid acid, with not acid; phosphoric other than red fuming gen fluoride, fluoric acid chloride, anhy- drochloric 1831: sulfuric acid, fuming; sul- more than 51% acid, liquid; phos- 2032: nitric acid, anhydrous drous acid; hydro- furic acid, fuming, with less than acid phoric acid, solid; fuming; nitric acid, 2186: hydrogen chloric acid, 30% free sulfur trioxide; sulfuric phosphoric acid, red fuming chloride, refriger- solution acid, fuming, with not less than solution ated liquid 30% free sulfur trioxide 3453: phosphoric 1832: sulfuric acid, spent acid, solid Emergency Guide 137 Guide 157 Guide 154 Guide 157 Guide 125 Guide 157 Guide 125 Guide 157 Response [10] Notes: PEL: Permissible exposure limit REL: Recommended exposure limit IDLH: Immediately dangerous to life or health concentration TWA: Total weighted average STEL: Short time exposure limit ERG: Emergency Response Guidebook high-octane gasoline, electronics (mi- is subject to the U.S. Department of Materials selection crochips and printed circuit board Transportation Pipeline and Hazard- The materials of construction, as well cleaning) and uranium isotopes. It is ous Materials Safety Transportation as any lining or internal coating re- also used to etch glass or metal. regulations. Transportation of hazard- quirements should be determined by a ous materials in various forms (bulk, materials expert based on the acid, its Safety and emergency response pipeline or tank cars) is subject to concentration and storage conditions. Because acids are mostly hazardous Title 49 of the Code of Federal Regula- Aqueous acid solutions are very cor- chemicals, their toxicity levels and in- tions (49 CFR). rosive, and usually require special ma- compatibilities need to be taken into In the event of spills of these acids terials depending on the temperature account when storing and transport- or other hazardous materials, only or phase. ing them, as well as how to respond in properly trained personnel such as Some recommendations are given the event of a spillage. firemen and policemen (or properly regarding the correct material selec- Permissible exposure limits (PEL) for trained plant personnel) should be in- tion depending on acid, such as in the hazardous materials are given by the volved in the emergency response and following reference for H2SO4: NACE U.S. Occupational Safety and Health containment of the product. RP0391 — Materials for the Han- Administration (OSHA) regulations: The Emergency Response Guide- dling and Storage of Concentrated 29 CFR 1910.1000, 29 CFR 1926.55 book 2008 (ERG2008) provides guide- (90 to 100%) Sulfuric Acid at Ambient and 29 CFR 1915.1000 for the general, lines for managing emergencies when Temperatures; HF: NACE 5A171 — construction and maritime industries, hazardous chemicals are involved. Materials for Storing and Handling respectively. Other toxicity levels, such This guidebook is available in printed Commercial Grades of Aqueous Hy- as the Recommended Exposure Limit form, and can also be downloaded in drofluoric Acid and Anhydrous Hydro- (REL) and Immediately Dangerous convenient electronic form, includ- gen Fluoride. to Life and Health Concentrations ing applications for smart phone that Depending on the acid and stor- (IDLH) are published in the U.S. Na- allow for quick searches of the chemi- age, transport or process conditions, tional Institute of Occupational Safety cals and their associated guides. A new interior coatings or linings could also and Health (NIOSH) Pocket Guide version of the Emergency Response be considered. For instance, rail tank to Chemical Hazards. The chemical Guidebook is scheduled for release cars transporting concentrated sulfu- incompatibilities, health effects and this year (2012). ric acid should be internally coated other concerns when handling or stor- The chemical safety data for the according to NACE SP0592 — Appli- ing hazardous chemicals are also given acids covered in this article, including cation of a Coating System to Interior in the NIOSH Pocket Guide. toxicity levels, incompatibilities and Surfaces of New and Used Rail Tank In the U.S., transportation of these emergency response guides are sum- Cars in Concentrated (90 to 98%) Sul- acids or other hazardous materials marized in Table 2. furic Acid Service.

28 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 TABLE 3. MATERIALS OF CONSTRUCTION, CLADDING & LINING [12]

Materials of H2SO4 construction Aluminum alloys may be used to handle dilute (concentration below 10%) and concentrated Aluminum acid (above 98%). It suffers corrosion for handling sulfuric acid in a range of concentration of 40–95 % It can be used to handle concentrated sulfuric acid at ambient temperatures under static and Carbon steel low-velocity condition. Corrosion resistance depends on temperature, acid concentration, iron tanks with flat bottoms and oper- content and flowrates ating pressures less than 0.14 barg Alloys with 14.5% content of silicon have shown best resistance to corrosion for sulfuric acid Cast Iron (2.5 psig) handling in all concentrations at temperatures up to the boiling point • API STD 620 — Recommended Copper Copper and copper alloys are not suitable for sulfuric acid handling Rules of Construction of Large, It has shown high resistance to corrosion in sulfuric acid handling up to 70% concentration. Lead Although, this material is not recommended for pumps or valves Welded, Low Pressure Storage Nickel 200 demonstrates good tolerance to sulfuric acid when it is handled at low or moder- Tanks: for vertical tanks with flat Nickel ate temperatures bottoms and operating pressures It can be used for handling sulfuric acid at concentrations below 95% under oxidizing condi- between 0.14 barg and 1.03 barg Niobium tions (2.5 psig and 15 psig) Exhibits excellent resistance to sulfuric acid up to 250°C (480°F) and is used when no corro- Gold • ASME BPV Code, Sect VIII, Div 1: sion can be tolerated for other operating pressures Platinum Resists sulfuric acid in all concentrations and temperatures Special design criteria, such as par- Palladium It is attacked by sulfuric acid in the presence of air ticular corrosion allowances or nozzle Rhodium In wrought or cast form rhodium is not recommended for handling sulfuric acid design, are also considered in acid Concentrated sulfuric acid turns extremely corrosive in presence of 316 and 304 stainless storage tanks — either by special com- Stainless steel steels. The conventional austenitic grades show good resistance in dilute or highly concen- trated acid at moderate temperatures pany or supplier criteria, or from pro- It is slowly dissolved by dilute sulfuric acid; corrosion resistance depends on the concentra- fessional associations. For instance, Zinc tion of the acid and the purity of the metal concentrated sulfuric acid tanks de- sign should follow NACE SP0294 — TABLE 4. MATERIALS OF CONSTRUCTION, CLADDING & LINING [12] Design, Fabrication, and Inspection of Storage Tank Systems for Concen- Materials of H3PO4 construction trated Fresh and Process Sulfuric Acid Aqueous solutions of phosphoric acid with concentration of 5 to 85% are highly corrosive and Oleum at Ambient Temperatures. for alloys 1100. Consequently this material is not recommended for phosphoric acid han- Aluminum Tanks should allow access to the dling top nozzles and the vent system, and offer an appropriate facility for sam- All cast irons can be considered to handle phosphoric acid; although the presence of contaminants must be previously evaluated since it can provoke severe cases of corrosion. pling. Periodically, it is necessary to Cast Iron High-silicon cast irons are ideal to manage phosphoric acid in all concentrations at any homogenize the contents of the tank, temperature, no presences of fluoride ions (F-) are allowed because the acid that remains on the Copper and copper alloys can be used to manage pure phosphoric acid solutions in heat- surface establishes a vapor-liquid Copper exchanger tubes, pipes and fittings. System impurities can accelerate the rate of corrosion equilibrium in which toxic and corro- more than acid concentration sive gases are released, so a recircula- It is extensively used in the manufacture of phosphoric acid. It is highly resistant to corro- Lead sion tion system is recommended. Special attention should be given to Nickel alloys are appropriate for handling phosphoric acid. For dilute acid alloys 20Cb-3 Nickel and 825 are recommended; for concentrated acid at high temperatures alloy B-2 offers the the acid physical properties in stor- highest corrosion resistance age to prevent freezing, high corrosion Niobium Resistant to corrosion for handling acid at temperatures below 100°C in all concentrations rates or vaporization. In general, corrosion rates increase Resistant to corrosion for handling acid at temperatures between 160 and 200°C in all Silver concentrations at higher temperatures, so acids Resistant to corrosion for handling acid at temperatures up to the boiling point in all con- should be stored at the lowest pos- Tantalum centrations in absence of fluoride ions (F–) sible temperature without freezing Conventional austenitic stainless steel has shown elevated corrosion resistance for all con- the acid. Higher corrosion rates could Stainless Steel centrations of phosphoric acid up to 65°C (150°F) also result from heating of the metal surfaces due to sun radiation, so the Tables 3–8 list some common metal Tanks for acid storage are usually tank exterior should be painted with alloys used in the CPI, along with their built of either metal (lined or non- a radiation reflecting color, such as general acceptable use ranges (concen- lined), or fiber reinforced plastic (FRP). white. Another regular measure to trations and temperatures) for each of Metal tanks offer a higher durability, maintain acids at an appropriate the acids covered in this article. and can also resist higher stresses or temperature is coating the tank with impacts; whereas FRP tanks are eco- an adequate material such as vinyl- Storage tanks nomical, usually chemically inert, and based materials. Usually aboveground storage tanks can be a good alternative for low-vol- In places where the storage tem- (ASTs) are used to store acid as they ume, short storage times. perature could be below the acid facilitate accessibility to tanks and The mechanical design of tanks for freezing point, storage tanks and ves- ancillary equipment for inspection acid storage usually follows either of sels should be provided with heating and maintenance. The storage tank the following codes: facilities, such as plate coils mounted should be sized for at least 50% more • API STD 650 — Welded Steel on the outside of the tank wall, or ex- volume than required. Tanks for Oil Storage: for vertical ternal heat exchangers connected to

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 29 TABLE 5. MATERIALS OF CONSTRUCTION, CLADDING & LINING [12]

Materials of con- HNO3 Cover Story struction Aluminum alloys commonly used for nitric acid services are 1100 and 3003. Corrosion de- Aluminum pends on temperature and concentration of the acid. Aluminum alloys are compatible with ni- tric acid at temperatures up to at least 71°C (160°F) when it is inhibited by hydrofluoric acid Cast iron can be used for handling concentrated nitric acid under control conditions such as the tank. Internal heating coils are Cast iron not recommended, because excess low temperature and low velocity. Corrosion attacks when handling dilute nitric acid For concentrations of 0 to 65%, most AISI 300-Series stainless steel has shown great corro- temperature in the coil walls acceler- Stainless steel sion resistance for temperatures up to the boiling point ates corrosion and could cause leaks. Also, high-pressure steam is not rec- Copper Not suitable for use in nitric acid ommended as a heating medium since Lead It can be used for concentration between 52 and 70% heat exchange surfaces could exceed Molybdenum Not suitable for use in nitric acid 100°C, causing severe corrosion. Nickel alloys are widely used in the production of nitric acid. Alloy 617 offers an excellent Pressurized storage is required Nickel performance and corrosion resistance for handling nitric acid at high temperatures in the when the vapor pressure exceeds the catalyst-support grids in high pressure plants atmospheric pressure at the storage Niobium It is completely resistant to nitric acid in all concentration at temperatures below 100°C temperature. Gold It is resistant to nitric acid in concentrations up to 50% above that it is attack by corrosion Common guidelines for acid storage Palladium It is vulnerable to attack from corrosion when nitric acid is in presence of air tank design are summarized in Chem. In wrought or cast form rhodium is resistant to corrosion produced by concentrated nitric acid Rhodium Eng. May 2008, Facts at your Finger- at 100°C tips: Acid Storage. Silver Not suitable for use in nitric acid When storing acids above ground, Tin Not suitable for use in nitric acid. Complex reaction occurs containment is also an issue. Tanks Appropriate for handling nitric acid at any concentration in temperatures below the boiling point. As temperatures exceed 80°C (175°F), corrosion becomes stronger depending on nitric should be properly diked, or double Titanium walled, to contain spills. In general, acid purity. Titanium alloys can’t be used for red fuming nitric acid due to a violent reaction that can take place in the system containment should be at least for one tank volume (if not properly drained), TABLE 6. MATERIALS OF CONSTRUCTION, CLADDING & LINING [12] or less provided there is adequate Materials of con- HF drainage to an acid neutralization struction pit, with blockage valves accessible Aluminum Unsuitable for handling hydrofluoric acid to operators. Local code requirements Stainless-steel type 304 has a good performance for handling anhydrous hydrogen fluoride should also be addressed when de- Stainless steel up to 200°C (390°F), it has poor resistance to dilute or concentrated hydrofluoric acid. On the signing acid-tank containment; for other hand stainless-steel type 316 can be used for handling dilute acid at low temperatures The use of copper alloys is affected by aeration and velocity, its corrosion resistance depends instance, the U.S. State of Florida has Copper specific requirements as given by Rule on the concentration and temperature Fair corrosion resistance in a wide range of concentration and temperatures for handling Lead 62-762.891 — Mineral Acid Storage hydrofluoric acid. Not recommended for handling dilute acid Tank Requirements. It offers great corrosion resistance to aqueous and anhydrous hydrofluoric acid with concen- Molybdenum trations up to 50%, below 100°C (212°F) Pumps Nickel 200 is ideal for handling hot anhydrous hydrogen fluoride vapor, but it is not recom- Nickel The design basis should be set before mended for handling hydrofluoric acid in aqueous solutions selecting a pump, that is, the operat- Niobium Unsuitable for handling hydrofluoric acid ing conditions such as temperature, Tin Unsuitable for handling hydrofluoric acid suction pressure, acid concentration, Titanium Unsuitable for handling hydrofluoric acid and so on. Zirconium Unsuitable for handling hydrofluoric acid A primary issue that must be taken into account while pumping acids is In order to select the piping mate- are suitable; they can be manually op- safety, so, the selected pump for the rial, the following aspects have to be erated or be fitted with actuators. system cannot leave place for leak- defined: acid concentration, transport Materials for different parts of the age; this is an advantage regularly temperature, phase, fluid velocity, valves (disk, stem and seat) should be offered by vertical submerged pumps type of flow, impurities in the acid and selected according to the acid concen- over horizontal pumps. Also, material solids presence. tration and operating conditions, by selection guidelines shall be followed Corrosion is often related to an consulting the valve manufacturer. to avoid casing, impeller or other in- acid’s velocity. In order to maintain a Some common materials according ternals damage. low velocity of the fluid, a bigger pipe to the acid to be handled are presented diameter is suggested. in Tables 9–13. Piping and fittings Selecting pipe material and designing Valves Acid handling the pipe system is a very important Valves are used for various functions, Sulfuric acid. Sulfuric acid must be issue in a plant, especially while han- including the following: stored separately from combustible dling acids. The system must ensure For blocking, gate valves or plug and reducing substances in a well- the acid is transported safely and ef- valves are regularly used. However, ventilated environment at tempera- ficiently. Piping should have as few plug valves are preferred for this ser- tures below 23°C (73.4°F). Concen- flanges as possible, so the chance of vice, to ensure proper valve operation. trated acid needs to be isolated from having leaks becomes negligible. For control, globe or butterfly valves water, as it may react violently, releas-

30 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 TABLE 7. MATERIALS OF CONSTRUCTION, CLADDING & LINING Materials of con- HCl struction

It is not appropriate for handling HCl; it has no resistance to corrosion Aluminum

Unalloyed cast iron systems are unsuitable for handling HCl, especially if high velocities References Cast Iron are involve. A high-silicon iron alloyed with small amounts of molybdenum, chromium and 1. Perry, R., Green, D. W., & Maloney, J. O. “Perry’s copper can be used to handle hydrochloric acid up to 95° C (200°F) at all concentrations Chemical Engineers’ Handbook,” McGraw- Corrosion attacks stainless steel (316) and stainless steel (304) when handling HCl at any Hill, N.Y., 2008. Stainless steel concentration or temperature 2. Davenport, W. G., and King, M. J., Sulfuric Acid Properties, In Sulfuric Acid Manufac- Copper can be used to handle dilute hydrochloric acid only, due to its sensitivity to velocity, Copper ture: Analysis, Control and Optimization, aeration and oxidizing impurities Elsevier, pp. 287–291, 2006. It exhibits tolerance to corrosion at 24°C (75°F) and concentrations up to 15%. It is unsuit- 3. DKL Engineering, Inc.,. Technical Manual, Lead able for concentrated acid at higher temperatures April 12, 2003. Retrieved July 6, 2012, from Sulfuric Acid Properties: www.sulphuric- Pure nickel and nickel-copper alloys can be used for handling hydrochloric acid below 10% acid.com/techmanual/Properties/proper concentration, without air presence, at low temperatures. The lower the concentration the ties_acid_properties.htm Nickel higher can be the temperature of the system; for example, HCl at 0.5% can stand tempera- 4. Material Safety Data Sheet, Nitric acid, 65% tures up to 200°C before corrosion attacks the alloy MSDS. It has shown excellent corrosion resistance to handle HCl at any concentrations and tem- 5. Potash Corp., Purified Phosphoric Acid, Tech- Niobium peratures up to 100°C (212°F) nical information bulletin, PCS Sale — In- dustrial Products, 2005. It can be used for handling hydrochloric acid at any concentrations and atmospheric pres- Gold 6. U.S. Dept. of Labor, Occupational Safety and sure up to the boiling point Health Administration (OSHA). Retrieved Palladium Unsuitable for handling hydrochloric acid May 14, 2012, from Regulations: 29 CFR 1910.1000 (General Industry): www.osha.gov/ In cast or wrought form, rhodium has excellent corrosion resistance to handle concentrated pls/oshaweb/owadisp.show_document?p_ Rhodium hydrochloric acid in temperatures up to 100°C (212°F) table=Standards&p_id=9991 7. U.S. Dept. of Labor, Occupational Safety Silver It is very susceptible to aeration when concentration and temperature are high and Health Administration (OSHA), Re- trieved May 16, 2012, from Regulation: It has shown excellent corrosion resistance to handle HCl at any concentrations under 29 CFR 1926.55 (Construction Industry): Tantalum atmospheric pressure and temperatures up to 90°C (195°F). It can be used to handle acid www.osha.gov/pls/oshaweb/owadisp.show_ with concentrations below 25% up 190°C (375°F) document?p_table=Standards&p_id=10628 Titanium Unsuitable for handling hydrochloric acid 8. U.S. Dept. of Labor, Occupational Safety and Health Administration (OSHA), Re- trieved May 16, 2012, from Regulation: 29 CFR 1915.1000 (Maritime): www.osha.gov/ TABLE 8. MATERIALS OF CONSTRUCTION, CLADDING & LINING pls/oshaweb/owadisp.show_document?p ACIDS COMMON ALLOYS _table=standards&p_id=10286 9. National Institute of Occupational Safety and For dilute and intermediate sulfuric acid (between 40 and 80% concentration) Incoloy alloys 25- Health, “NIOSH Pocket Guide to Chemical 6MO, 825, 020 and Inconel alloy G-3 have shown excellent corrosion resistance for temperatures up Hazards”, NIOSH Publications, 2007. to 50 °C (120°F). When handling aggressive acid, Inconel alloys 625, 622, C-276 and 686 are suit- H SO able. For reducing conditions, Monel alloy 400 is appropriate in the absence of air for temperatures 10. U.S. Dept. of Transportation, “Emergency Re- 2 4 sponse Guidebook 2008 (ERG2008)”, 2008. up to boiling point for concentrations below 15%. For storage of H2SO4, Monel alloy 400 can be used at room temperatures up to 80% concentration. Hastelloy B3, C-2000 and G-30 are also suitable for 11. Grossel, Stanley S., Safe, Efficient Handling handling sulfuric acid of Acids, Chem. Eng., July 1998, pp. 88–98. Chromium enhances corrosion resistance in alloys while handling nitric acid, due to this fact, Incoloy 12. ASM International, (2002). Handbook of Cor- rosion Data, 2002.13. API Std. 620. alloy 800 and 825 are adequate for nitric acid at all concentrations for temperatures up to the boiling point. Inconel alloy 600 and C-276 also offer good corrosion resistance to nitric acid for concentra- 14. API Std. 650. HNO 3 tion over 20% at room temperature; alloy 690 has shown better corrosion resistant because its 15. ASME Boiler and Pressure Vessel Code Sec. chromium content is higher. Hastelloy G-30 alloy and G-35 offer excellent corrosion resistance for VIII Div 1. this same reason 16. DKL Engineering, Inc., Technical Manual, When handling phosphoric acid, Incoloy alloys 825, 020 and 25-6MO, as well as Inconel alloy G-3 December 20, 2005, Retrieved July 6, 2012, are suitable and regularly used. For extreme conditions such as high temperature and high amount of from Strong Acid System — Piping, www. H3PO4 impurities or halides contaminants, Inconel alloys 625, 622, C-276 and 686 are recommended. Has- sulphuric-acid.com/techmanual/strong%20 telloy alloys B-3 and G-30 stand phosphoric acid in all concentrations and temperatures. Hastelloy acid/sa_piping.htm alloy G-35 was especially designed for phosphoric acid wet processing in fertilizers manufacture 17. International Program on Chemical Safety, Chemical Safety Information from Intergov- Incoloy alloys 25-6MO, 825 and 020, and Inconel alloy G-3 are used for dilute hydrochloric acid ernmental Organizations, April 2000, Re- handling. Another alloy that offers good corrosion resistant in concentrations below 10% with aer- trieved May 12, 2012, from Hydrogen Chlo- ated conditions at room temperature is Monel alloy 400. Nickel alloy 200 can be used at room ride: www.inchem.org/documents/icsc/icsc/ HCl temperature for concentrations up to 30% as well. For environments that contemplate the presence eics0163.htm of oxidizing contaminants and hot hydrochloric acid, Inconel alloys 625, 622, C-276 and 686 are rec- 18. Pohanish, R. P. , “Sittig’s Handbook of Toxic ommended. Hastelloy alloys B-3, C-2000 and G-30 are also suitable for handling hydrochloric acid, and Hazardous Chemicals and Carcinogens”, at all concentrations and temperatures Elsevier, 2012. The formation of fluoride films is key on engineering materials in order to offer good corrosion- 19. Southerm States Chemical A Dulany Indus- resistance rates while handling hydrofluoric acid. Monel alloy 400 is widely used for this purpose, tries Co., Chemical Safety Handbook, 2002. due to the fact that it has shown excellent corrosion resistance for all hydrofluoric acid services in all 20. The Dow Chemical Company, June 2008, HF concentrations and temperatures up to (and even above) the boiling point. For anhydrous hydrogen 2008, Retrieved July 9, 2012, from Prod- fluoride up to 82°C (180°F), Nickel alloy 200 is commonly used. For dilute HF and temperatures up to uct Safety Assessment: Nitric Acid: http// 70°C (158°F) Inconel alloy 600 can also be used. Other alloys like Hastelloy C-2000 and Hastelloy msdssearch.dow.com/publishedliterature- G-30 are also recommended for handling hydrofluoric acid DOWCOM/dh_0131/0901b80380131028. pdf?filepath=productsafety/pdfs/noreg/233- 00312.pdf&fromPage=GetDoc ing heat. If sulfuric acid needs to be as gloves, a vapor respirator when 21. U.S. Dept. Transportation, Electronic Code of Federal Regulation. Retrieved May 14, diluted or combined with water, then ventilation is inadequate, face shield 2012, from Chapter I Pipeline and Haz- it has to be added to water carefully. and full suit shall be used. ardous Materials Safety Transportation regulation: http://ecfr.gpoaccess.gov/cgi/t/ To manipulate sulfuric acid, proper Nitric acid. Nitric acid must be text/text-idx?c=ecfr&tpl=/ecfrbrowse/ personal protective equipment, such stored separately in a corrosion resis- Title49/49cfrv2_02.tpl

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 31 TABLE 9. SPECIFIC EQUIPMENT, PIPING, VALVES AND PROTECTIVE Cover Story CLOTHING GUIDELINES Equipment H2SO4 Iron sulfate is produced in storage tanks of sulfuric acid; it is a consequence of interaction between the tank’s surface and the acid. Usually iron sulfate precipitates, therefore the pump suction pipe should be placed above the tank bottom to avoid pumping solid residues that can tant location, avoiding contact with Tanks compromise pump well-functioning. Under the same line, storage tanks must provide a facility powders, carbides, hydrogen, sulfide, to clean the tank bottom. The tank’s maintenance should be performed periodically according turpentine and strong bases. Along to the laws of the state and the company policies the same lines it is important to men- According to the plant requirements, pumps used for sulfuric acid handling are usually hori- tion that nitric acid’s storage requires zontal centrifugal pumps or heavy duty vertical, submerged type special conditions, such as adequate For handling sulfuric acid at 93.19% (66 °Bè) usually horizontal centrifugal pumps with me- Pumps ventilation and especially low tem- chanical seals are used peratures to ensure a cool environ- Common materials of construction are: cast iron or Alloy 20 wetted ends, Alloy 20 plunger, ment for the solution, because heat tetrafluoroethylene plastic chevron packings may cause containers to burst and For sulfuric acid service, welded pipe lines with schedule 80 are commonly used, these pipes result in escape of poisonous gases; should be kept full of acid to minimize corrosion attacks. Sulfuric acid also promotes hydrogen so it should not be stored above 23°C Piping and gas formation; for this reason it is necessary to avoid pressure buildup by venting the line fittings (73.4°F), and the container must re- In case of draining the pipe, the use of air is not recommended, because it can accelerate cor- main dry and locked up. rosion. Nitrogen can be used for such purposes Nitric acid and its vapors can cause Butterfly Valves: Lead is an adequate stem and disk material for sulfuric acid at all concentra- severe damage during its handling to Valves tions; for concentrations lower than 75% at low temperatures Alloy 20 and Hastelloy have also persons who have contact with it; the been used. The seat should be made of PVF, with Viton and Hypalon also been used severity of the damage is related to Properly fitted chemical safety goggles, face shield (8-in. high minimum) and protective cloth- ing should be worn. Acid-proof clothing should be fitted snugly at neck and wrists, in a manner the time of contact or exposure and preventing drainage of acid to gloves or boots. Impervious rubber or polyvinyl chloride gloves Protective the acid concentration. with gauntlets covering forearms should be used. Boots made of the same material should be clothing Every process that involves nitric worn, with tops being covered by the trousers. Head protection via hard hat or full cover acid hood should be worn, as well as a respirator for protection against fumes acid handling or storage must contem- plate an adequate ventilation system that ensures airborne levels below the TABLE 10. SPECIFIC EQUIPMENT, PIPING, VALVES AND PROTECTIVE safety exposure limits allowed, not CLOTHING GUIDELINES only this measure needs to be taken into account but also workers should Equipment H3PO4 be aware of the risks arising from Heating coils should be provided in order to maintain the phosphoric acid above its freezing point, depending on ambient conditions and acid concentration. For instance, 85% H PO Tanks 3 4 management of nitric acid. freezes at 21.1°C Phosphoric acid. Phosphoric acid can be described as a stable chemical, All fittings should have wetted parts of 316 L stainless steel, with mechanical seals rather than packing. Centrifugal pumps are also used for phosphoric acid handling because it is not subject to thermal Pumps decomposition. However, the design criteria for its handling should be Stainless steel 316 is regularly used for piping because it has shown excellent results in cor- based on the acid concentrations and rosion resistance for all concentrations of phosphoric acid, even though the piping material operating temperatures. The most Piping and can be the same used for storage important issue about this acid is the Fittings When using stainless steel, the fittings and valves should be welded or flanged; screwed fit- variation of its freezing point accord- tings are not recommended because they may allow leakage ing to its concentration; the freezing Butterfly valves: 316 SS, Alloy 20 and Hastelloy C are good stem and disk materials for phos- point of standard concentrations are Valves phoric acid at various concentrations, with Monel also showing fair results. Common seat –17.5°C (0.5°F) at 75%, 4.6°C (40.2°F) materials include: PVF, Neoprene, Hypalon, Viton or EPT at 80% and 21.1°C (70.01°F) at 85%, Properly fitted chemical goggles and protective clothing should be worn. Impervious gloves and aprons are recommended. No special respiratory protection is required under ordinary therefore it becomes necessary to Protective conditions of use, provided that adequate ventilation is maintained. When vapor or mist con- Clothing heat phosphoric acid at high concen- centrations exceed applicable standards, approved respiratory protective equipment must be trations in order to maintain the acid used as a liquid solution. Unlike other acids, phosphoric acid skin and generates destruction of tis- relief valves, emergency dump sys- does not react violently with metals; sue and severe bone damage. tems); and personal protection equip- reaction occurs slowly and progres- Package sizes range from 500–1,000 ment (appropriate clothing). sively with hydrogen as a product, so, mL for analytical products, to 10,000-L When boiling all aqueous solutions, caution should be exercised because ISO containers. HF is delivered com- HF forms an azeotropic constant boil- the vapors formed are flammable. mercially in concentrations of 98 wt.%, ing mixture that contains 35.6% (by Hydrofluoric acid. HF acid is a very 48–51 wt.% and 40 wt.%. weight) HF and boils at 111.35°C hazardous material, both in liquid and Due to HF’s nature, strict measures (231.8 °F). vapor phase. It can cause severe burns, shall be taken when handling the acid Hydrochloric acid. HCl must be which may not be immediately pain- in industrial facilities. Such measures stored in a corrosion resistant loca- ful or visible. HF is a strong irritant include administrative controls (for tion. Even though the acid is non- to the skin, eyes and respiratory tract. example, work permits); engineering flammable, when it is heated hy- The fluoride ion easily penetrates the controls (instrumentation: detectors, drochloric acid fumes are released,

32 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 TABLE 11. SPECIFIC EQUIPMENT, PIPING, VALVES AND PROTECTIVE CLOTHING GUIDELINES

Equipment HNO3 For acid grades lower than 95 wt.%, tanks should be designed for slight pressure and vac- uum, with fumes collected at a disposal system and sent to a scrubber. Vent piping should Tanks be designed taking into consideration possible corrosion from contact with moisture the following compounds: chromate, permanganate and sulfate. Such re- Wetted parts should be made of 304L stainless steel for concentrations lower than 95 wt.%; for higher concentrations, they should be made of titanium (with a water content actions generate chlorine gas as a Pumps higher than 1.34% to prevent spontaneous combustion), silicon iron or 3003 aluminum result. A subsequent reaction occurs alloy [11] with metal peroxide forming its cor- Piping made of 304L stainless steel is frequently used for HNO up to 95 wt.%, and of alumi- responding chloride. Piping and Fit- 3 num for higher concentrations. Carbon steel (CS) piping with TFE, FEP or glass linings (up to When storing hydrochloric acid, tings 11 certain temperatures) can also be used for all grades. [ ] proper ventilation has to be ensured Butterfly valves: 316 SS, Alloy 20 and Hastelloy C are good stem and disk materials for nitric in order to maintain the acid concen- acid at various concentrations. Seats made of Viton can handle various concentrations up to Valves 70%; for low concentrations at low temperatures, Neoprene, Hypalon and EPT have also been tration in air below the permitted used limit of exposure. ■ Protective Edited by Gerald Ondrey Neoprene or natural rubber latex gloves are acceptable for handling nitric acid. Clothing

TABLE 12. SPECIFIC EQUIPMENT, PIPING, VALVES AND PROTECTIVE Authors CLOTHING GUIDELINES Alberto Baumeister is the CEO and co-owner of the Equipment HF Ecotek group of companies, which is located in the City Anhydrous and 70 wt.% HF up to 66°C, or HF between 60 to 70 wt.% up to 38°C, can be of Knowledge, Panama (Calle stored in carbon steel (CS) tanks, since the metal is passivated with an iron fluoride film 60, PH Obarrio 60, Piso 15, Tanks when the fluid is in contact with the metal. Hydrogen corrosion may occur in steel tanks. Ofc. 15-A, Obarrio, Panamá, Rep. De. Panamá; Phone: Other grades of HF can be stored in tanks made of CS with natural rubber lining, polyethyl- +507-203-8490; Fax: +507- ene or unplasticized PVC [11] 203-8491; Email: abaumeis- [email protected]). He has Diaphragm pumps with TFE or polychlorotrifluoroethylene (CTFE) diaphragms can handle experience as coordinator and anhydrous, 70 wt.% and electronic-grade HF. senior process consultant in engineering projects Pumps Centrifugal pump materials depend on grade: Ni-Cu alloy of Alloy 20 is used for anhydrous for the chemical, petrochemical, refining, oil and HF, Vinylidene chloride (VC)-lined steel for 70 wt.% and electronic-grade HF, and Penton- gas industries. He has a Master’s Diploma in lined steel or solid Penton for electronic grade HF [11] water treatment management from Universidad de León (Spain, 2011), a specialization in man- Anhydrous and 70% wt HF can be transported in seamless CS piping. The rating and sched- agement for engineers at Instituto de Estudios ule should be selected according to the operating pressure and corrosion allowance, with Superiores de Administración (Venezuela, 1990), Piping and fit- Sch 80 and Sch 160 commonly used for both grades, respectively. CS with VC, TFE and FEP and a degree in chemical engineering from Uni- tings versidad Metropolitana (1987), graduating first lining is also used, depending on fluid temperature. of his class. He has been a professor of the Chem- Electronic-grade HF can be transported in unplasticized PVC pipe ical Engineering School at Universidad Metro- politana between 1995 and 2007 and has written Butterfly valves: Hastelloy C is the best material for the stem and disk, with Alloy 20 also several technical publications for international Valves exhibiting fair results. Common seat materials include: PVF, Hypalon and Viton; for pure associations. (100%) HF, only PVF or Viton should be considered Sebastiano Giardinella Protective Neoprene and natural rubber gloves are excellent for handling hydrofluoric acid in all con- is the vice president and co- Clothing centrations, glove change is necessary before 8 hours owner of the Ecotek group of companies (same address as above; Email: sgiardeinella@ TABLE 13. SPECIFIC EQUIPMENT, PIPING, VALVES AND PROTECTIVE ecotekgrp.com). He has ex- perience as process leader, CLOTHING GUIDELINES and in project planning and control, in engineering proj- Equipment HCl ects for the chemical, petro- chemical, refining, oil and gas Outdoor tanks are preferred for storing hydrochloric acid; some common measures of pro- industries. He is a certified tection when tank is placed indoors are coating the floor with asphalt or another corrosion project management professional (PMP), has Tanks resistant material to prevent several damages in case of leaks or spills. The tank must be Master’s Degree in project management from provided with a vent so acid fumes do not accumulate in the tank and a drainage system so Universidad Latina de Panamá (Panama, 2009), maintenance can be performed periodically. Vents should be routed to a scrubber and a degree in chemical engineering from Universidad Simón Bolívar (Venezuela, 2006), graduating summa cum laude; and is currently Pumps similar to those used for H2SO4 and H3PO4 can be used. Centrifugal pumps lined with, or constructed of TFE, PVDF of Derakane are commonly used. a student of the M.Sc. in renewable energy de- Pumps velopment at Heriot-Watt University (Scotland). Mechanical seals of carbon and ceramic faces with TFE or fluoroelastomer secondary seals, 11 He is also professor of project management at and Hastelloy C metal parts, are also recommended [ ] Universidad Latina de Panamá, and has written technical publications for Chemical Engineering Piping and fit- CS piping with TFE, PVDF, Derakane or polypropylene lining is frequently used for HCl. magazine, international associations and aca- tings PVC or FRP piping have also been used, depending on fluid pressure demic institutions. Butterfly Valves: common stem and disc materials include: lead or Hastelloy C. Common seat Mayhell Coronado is a pro- Valves materials include: PVF, Neoprene, Hypalon and Viton cess engineer of the Ecotek group of companies (same Protective cloth- For concentrations up to 40% neoprene and fluoroelastomer gloves are recommended for address as above; email: ing handling hydrochloric acid. For concentrated acid, butyl gloves are suitable [email protected]). She has experience in the de- velopment of conceptual and which can compromise the safety and and it is advisable for them to take a basic engineering projects for the oil and gas, and chemical toxicity levels allowed, therefore stor- shower and gargle with sodium bicar- industries, as well as in sup- port to company management. age tanks need proper venting that bonate after manipulating the acid in She has a degree in chemical shall be directed to a safe location order to avoid teeth corrosion in other engineering from Universidad Metropolitana (Venezuela), where she taught thermodynamics, and treatment facility. activities performed by the operator. transport phenomena and general chemistry as Operators handling hydrochloric Undesirable reactions can take professor assistant, and has published a work on the effects of microbial contamination in diesel acid must wear protective equipment place between hydrochloric acid and fuel used for thermal power generation.

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 33 Feature Report From Batch to Continuous Processing

1,000 Continuous flow Reactor size reactors can provide 10 mL 100 mL 100 many benefits over 1 L 10 L

batch processes. Flow, L/h 10 100 L This article answers 1,000 L 10,000 L why and how 0 0 10 100 1,000 10,000 100,000 1,000,000 Robert Ashe Reaction time, s AM Technology FIGURE 1. Reactor sizes for a range of throughputs and reaction times are shown

mall chemical reactors offer a commercial throughputs. The solu- concentrated within a relatively small number of benefits compared tion to this problem is to use a flow number of individuals or groups. For to large reactors, such as better reactor. This is a channel or series of the wider industrial community, many Sheat transfer and mixing. While mixed stages in which process materi- basic questions relating to the busi- small batch vessels are impractical at als react as they flow through it. It is ness case and implementation meth- the industrial scale, continuous flow analogous to a series of small, stirred ods for adopting flow processes fail to reactors can provide the benefits of batch vessels on a conveyor belt. A get answered properly. For example, small physical size without the prac- flow reactor provides the benefits of the question of energy saving is often tical difficulties of multiple vessels. small physical size without the practi- dismissed on the grounds that the This article considers the four basic cal difficulties of charging and empty- temperature cycle in a flow reactor is needs of flow reactors (volumetric ing multiple small vessels. broadly similar to that of a batch reac- capacity, heat transfer, plug flow and Historically, flow reactors have tor and therefore, there is no net en- mixing) and how they influence choice been more common in bulk chemical ergy saving. This, however, disregards of equipment. processes where the problems of ves- the fact that a flow reactor may have sel size are most acute. With growing many tons less of hardware to heat Flow reactors pressure on chemical manufacturers and cool, and does not require a five- A small chemical reactor has a higher to meet ever-tougher cost and regula- fold oversizing of the utilities to cope ratio of heat transfer area to work- tory targets however, the range of ap- with uneven heating and cooling loads. ing volume than a large reactor. It plications for flow reactors has started Implementation of flow reactors also can also deliver more mixing energy to expand rapidly. remains far too reliant on trial-and- per unit volume without bending the Flow reactors are not new technol- error rather than systematic methods. agitator shaft. Since the outcome of ogy, but many of the applications they All too often good applications for flow most chemical reactions is linked in are now being developed for are new, technology get abandoned during tri- some way to mixing or heat transfer and as such progress is confronted by als for lack of the right equipment or (or both), small reactors have inherent the usual adoption problems of mar- operating methods. advantages over large ones. Depend- ket resistance, availability of the right There are difficult challenges for ing on the reaction type, these ad- equipment and lack of user knowhow. flow reactors, such as fouling and vantages can contribute toward sub- User knowhow is arguably the big- large solids. Apart from these how- stantially lower capital and operating gest hurdle to progress since most en- ever, flow reactors are easier to scale costs. Small batch vessels, however, gineers and scientists were trained in up than batch systems, since the size are impractical at the industrial scale batch methods and have had little ex- differences between laboratory and since hundreds or even thousands of perience with flow technology. While production scale are greatly reduced. process cycles would be required for good knowhow does exist, this is still Success, however, is contingent on a

34 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 FIGURE 2. In plug ow, the uid velocity across the face of a channel is uniform good understanding of the underlying The extent to which these benefits substitute for testing under flow con- process characteristics and a broad apply depends on factors such as pro- ditions. The equipment used for scale- knowledge of reactor types to address cess type, product value and through- up development should be as similar the specific needs. put. It also depends on whether the as possible to the full sized reactor. application is for an existing facility This generally favors the use of large Reasons for continuous or a new one. flow reactors for scaleup work rather The benefits of flow reactors vary ac- Manufacturers from the chemical than microreactors (other than where cording to the nature of the process, but process industries (CPI) often view microreactors can be used at the pro- they typically include the following: the batch versus continuous ques- duction scale). • Improved yield and quality — For tion as an either/or option, and reject competitive and consecutive re- flow reactors on the grounds that the Reactor capacity actions, flow reactors can deliver batch vessels are still required for The volumetric capacity of a flow re- significant improvements to yield work-up operations. While this may actor should be as small as possible. and purity be true in many cases, the commer- Apart from the obvious benefits of • Reduced solvent use — For heat- cial advantages of using flow reac- small footprint and higher perfor- transfer limited reactions, flow re- tors within existing batch processes mance, small flow reactors have actors can operate with leaner re- should not be underestimated. Flow proportionately lower startup and action mixtures and therefore with reactors generally occupy small foot- shutdown losses. The physical size is less solvent. Similarly, continuous prints and can be integrated within calculated from the relationship: countercurrent processes for opera- existing batch plants. Where flow re- tions, such as extraction, yield bet- actors can make a material difference Reactor size (L) = Throughput (L/s) × ter separation with less solvent to yield or reduction in batch fail- Reaction time (s) • Capital cost — For mixing or heat- ures, the commercial case for using transfer limited processes, flow re- them within existing batch processes Reactor sizes for a range of through- actors are smaller and often signifi- can be self-evident. There are also puts and reaction times are shown in cantly smaller than batch reactors. other reasons for using flow reactors Figure 1. Smaller physical size contributes within existing batch processes, such A flow reactor can be scaled up by to lower equipment costs as well as as debottlenecking, reducing energy a process of numbering up (or scaling smaller utilities and buildings. Capi- waste, more efficient use of solvents, out). For this, the channel size is kept tal expenditure reductions on build- improved safety, reduced problems of constant and capacity is increased by ing costs alone for a continuous plant bursting disc failure (which can dis- using multiple parallel channels of can amount to 50% or more [1] able an entire production facility) similar size. The size of the scaled up • Utility costs — Over 50% of the en- and increasing plant flexibility. system can be predicted accurately ergy used in a batch reactor is wasted when numbering up, since the func- on the hardware, cross mixing be- Understanding the process tional capabilities of the channels re- tween the heating and cooling fluids While microreactors can be used suc- main unchanged. and uneven utility loads. Flow reac- cessfully with very little process in- The reactor can also be scaled up tors can reduce this waste by 90% or formation, the same does not apply to by increasing the channel length, al- more by virtue of reduced physical larger flow reactors. Scaling up flow though scope for this is limited by size and steady state operation reactors by trial-and-error is difficult pressure drop. In some cases, longer • Plant flexibility — Batch reactors and potentially dangerous. A good un- channels will give better performance have good flexibility in terms of the derstanding of the process is required (due to higher velocities) and there- unit operations they can perform, before trials are undertaken. fore require smaller working capaci- but very limited flexibility in terms A variety of analytical devices can be ties than predicted. of working capacity. A flow reactor used to study flow processes, but one Increasing the tube diameter is often is more specialized in terms of unit of the most useful tools for generating the only practical way of scaling up, operations it can perform, but the design data is a reaction calorimeter, especially where high reactor volumes capacity per cycle can be varied by since this provides information about are required. Increasing the diameter, orders of magnitude by changing the both kinetics and heat of reaction. It however, often reduces performance, cycle time. This can contribute to is also worth noting that the differ- and therefore the scaled system may greater plant flexibility and there- ences between batch and flow reactors have to be larger than predicted to fore less process equipment relate to scale (there is no flow effect) compensate for the difference. • Safety costs — For hazardous pro- and a small reaction calorimeter with When scaling up, it is preferable to cesses, the cost of managing safety similar heat transfer and mixing char- use the maximum tube diameter pos- in small flow reactors is inherently acteristics (to the proposed flow reac- sible, subject to satisfactory perfor- cheaper than large batch reactors. tor) can provide reliable design data mance. Short, large-diameter tubes Small pressure vessels are cheaper for scaleup. have lower fabrication costs, a reduced to fabricate and require smaller Even where processes are relatively tendency to block and a lower pressure emergency-relief systems well understood however, there is no drop. They are also easier to clean.

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 35 Feature Report

FIGURE 3a. In a plug ow reactor, material is only retained in the reactor while it is reacting, and it cannot be discharged until the re quired residence time has elapsed

Plug flow some product is retained for longer Plug flow describes a flow pattern than required in the reactor and some where the fluid velocity across the unreacted material is discharged pre- face of a channel is uniform (Figure 2). maturely (Figure 3b). Good plug flow It also implies no back mixing and all is the key to minimizing reactor size FIGURE 3b. An example of a system fluid elements having the same resi- and optimizing yield and purity. A that is not plug ow is the continuously dence time. While plug flow is required common misconception is that plug stirred tank reactor (CSTR), which is for most applications, ideal plug flow flow is not required for zero order fully backmixed. In the absence of plug cannot be achieved in practice due to reactions (where the reaction rate is ow, reacted material is retained for lon ger than required, and unreacted mate the effects of molecular diffusion, sur- independent of reactant concentra- rial is discharged prematurely. It is there face drag, bends and obstructions in tion). This is not correct. Plug flow is fore inherently less efficient than either a the channel. important for virtually all processes, plug reactor or an ideal batch reactor Microreactors typically have chan- even for zero order reactions. The ex- nel diameters of less than 0.5 mm. In ception to this is fast zero-order reac- two phase mixtures. There are also these systems, the plug flow character- tions (typically a few seconds or less) different mechanisms for promoting istics benefit from low fluid velocities where reactor size is not a significant mixing, such as molecular diffusion, [2]. This is a useful characteristic as cost issue and there are no consecu- turbulent flow or splitting and fold- the reaction time can be varied from tive reactions. ing of fluid streams. In a flow reactor, less than a second to many minutes in For many applications, the benefits the optimum mixing condition is good relatively short channels. of good plug flow are not limited to radial mixing (mixing across the tube) In larger diameter channels, good residence time control. Where the re- with low axial mixing (mixing along plug-flow characteristics benefit from action rate is dependent on reactant the tube). high fluid velocities [2], and the chan- concentration (nth order reactions), Scale is important for mixing. For nel length has to be varied to suit the low back mixing reduces dilution of example, a small flow reactor can reaction time. Good radial mixing is unreacted material giving faster reac- blend a fluid in a fraction of a second, also desirable to prevent the fluid tion rates and higher yields per unit whereas a 1,600-L batch reactor can from separating into zones of fast volume. Plug flow also provides the take 10 to 20 seconds [3]. — and slow — moving fluid. Radial means for preventing material from Microreactors operate under lami- mixing can be achieved by means of over reacting, and reducing reactions nar flow conditions with Reynolds baffles, static mixing elements, dy- between reactants and product. numbers of typically less than one namic mixing and turbulent flow. A Where the outcome of a reaction hundred [4]. The flow streams are good approximation to plug flow can is particularly sensitive to plug flow, parallel, and these systems rely prin- also be achieved by using multiple high fluid velocities and long channels cipally on molecular diffusion for ra- stirred tanks in series, and the higher are desirable. From the perspective of dial mixing. Microreactors have a the number of tanks used the better. pressure drop and reactor cost, how- reputation for good mixing that is Above ten stages, however, the cost of ever, there are practical advantages not always deserved. For demanding additional stages starts to outweigh to minimizing channel length. A good mixing applications, such as with two the incremental benefits. compromise is to use long small-di- phase fluids, it is often necessary to Plug flow is determined by experi- ameter tubes where the reaction rate employ static mixing elements within mental methods such as dye injection is high (and therefore more sensitive the channel to promote radial mixing. tests. These data need to be treated to back mixing) and larger diameter The need for good radial mixing with care, because the quality of plug tubes where the reaction rate is slow. becomes increasingly important as flow required will change with the re- the diameter of a flow reactor is in- action rate. The observed quality of Mixing creased. Without radial mixing, large plug flow can also change as the phys- Mixing can be characterized in many tubes bring problems of poor blend- ical properties of the fluid changes. ways, such as applied mixing energy, ing, poor plug flow and reduced heat- Plug flow provides the means for uniformity of mixing, time to achieve transfer performance. separating reacted and unreacted ma- a uniform blend, Reynolds number There are two general methods for terial (Figure 3a). Without plug flow, or mass transfer characteristics for promoting radial mixing: dynamic

36 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Heat transfer capacities for different tube diameters and heat transfer coefficients 100,000

10,000 Heat transfer coefficient W/m2/°C and the heat transfer fluid (∆T). This 1,000 10 is typically in the range of 0 to 50°C, 100 but it can be higher where the pro- 100 1,000 cess fluid can tolerate extreme sur- face temperatures. Heat transfer capacity, W/L/°C 10 The amount of heat that can be 0.1 1 10 100 Tube diameter, mm transferred per unit volume of prod- uct (Q) is inversely proportional to FIGURE 4. Cooling capacities for different tube sizes and heat-transfer coefficients are shown here tube diameter (D). This means that the tube diameter needs to be small enough to cope with the process heat Temperature control in a flow reactor load. Cooling capacities for different 120 tube sizes and heat transfer coeffi- 1. No cooling cients are shown in Figure 4. 100 2. Single cooling Where the product can tolerate temperature, 80 two tube sizes extreme temperatures, heat transfer is not important to design and short 60 3. Single tube size, two cooling large-diameter tubes are preferable 40 temperatures for reasons of cost, low pressure drop Temperature , °C , Temperature 4. Single tube size, 20 and ease of cleaning. In such cases, single cooling temperature the feed and discharge temperatures 0 0 1 2 3 4 5 6 7 8 9 10 can be controlled by separate feed and discharge heat exchangers, respec- Volume through the reactor, L tively. If the process temperature can FIGURE 5. This example illustrates different approaches for temperature control rise above the normal boiling point, elevated operating pressures are re- quired to suppress boiling. Boiling in mixing and static mixing. In dynamic the reactor to maximize interfacial a flow reactor is undesirable as it re- mixing, mechanical stirrers generate area- and mass-transfer coefficients duces the working volume. radial mixing. In static mixing, radial • Where solids are present in the pro- Temperature control. For many mixing is promoted by either turbu- cess fluid, efficient mixing is required processes, good temperature con- lent flow or elements that break up the to keep them uniformly dispersed trol is necessary and reactor design flow pattern (baffles or static mixers). and free flowing. Dynamically mixed has to take account of variations in Mixing is a difficult parameter to flow reactors have the advantage of process heat load along the chan- characterize, and the mixing condi- keeping solids suspended if the flow nel. In microreactors, high levels of tions can also vary within the channel is interrupted. In a statically mixed heat can be added or removed with as the physical properties of the pro- system, an interruption to flow can low temperature differences between cess material changes. For this reason, lead to a serious blockage the jacket and the process fluid. This there is no substitute for testing. Some • Where the process fluid contains means that a single cooling strategy general considerations for mixing in fragile materials, such as crystals or can often be applied without causing larger systems include the following: live cells, mixing is constrained by serious overcooling where the process • Good radial mixing is required the need to prevent product damage heat load is low. In larger flow reac- throughout large flow reactors tors, higher temperature differences even when the process fluid is fully Heat transfer between the jacket and process fluid blended in order to maintain good In a tubular flow reactor, heat is added are necessary to compensate for the plug flow and where applicable, ef- or removed by a cooling jacket. The lower surface-to-volume ratios. If a ficient heat transfer amount of heat that can be transferred single cooling strategy is employed • For some processes, such as compet- per unit volume of product in a tube under these conditions, problems of itive reactions, mixing at the point (Qv) is determined by the relationship: overcooling can arise in areas where where reactant streams combine the process heat load is low (for ex- Q = (4 × U × ∆T)/D can be essential for optimum perfor- v ample at the end of an nth order reac- mance. For these, different mixing The heat transfer coefficient (U) is tion). While it is feasible to manage strategies may be required at the typically in the range of 50–1,500 W/ this with co-current flow (between inlet and early stages of the reactor m2/°C. There is little scope for varying the heat transfer fluid and process • Processes with more than one phase this since the parameters that deter- fluid), a more practical approach is to (solid, liquid, gas) usually have mass mine it are fixed by other needs. treat the channel as a series of stages transfer limitations. To overcome the The heat transfer rate can be con- with different channel sizes or jacket limitations, these processes require trolled by varying the temperature temperatures (to cope with different high mixing efficiencies throughout difference between the process fluid heat loads). The example shown in

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 37 Feature Report

Figure 5 illustrates different cooling FIGURE 6. This strategies for an exothermic reaction dynamically mixed plug ow reactor in a 10-L reactor: uses transverse • In the first case, no cooling is ap- mixing in tubes plied, and the tube diameter is 38 mm. The overall reactor length is 9 m, and the product temperature rises to over 100°C • In the second case, a single coolant temperature of 0°C is used. The first cooling stage (2 L) uses a 5-mm-dia. tube, and the second stage (8 L) uses These are generally larger systems diameter; Simple with low fabrication a 38-mm-dia. tube. The overall reac- suited to slower reactions and mul- cost; Low pressure drop in larger di- tor length is 109 m and the process tiphase mixtures ameter systems; Larger-diameter tu- temperature is held at 40–60°C bular reactors are easy to clean • In the third case, a single tube of Flow reactor types Disadvantages: High tube lengths 5-mm dia. is used. The first cooling This section summarizes common flow other than for short reaction times; stage (3 L) uses a cooling jacket at reactor types. It has to be accepted that Poor to moderate mixing, which limits 10°C, and the second stage (7 L) the comments are generalizations and performance with multiphase mix- uses a cooling jacket at 40°C. The there will be considerable overlap in tures; Tube lengths have to be varied overall reactor length is 509 m and terms of capabilities between different with reaction time; Poor to moderate the temperature is held at 40–60°C reactor types. solids handling and easily blocked if • In the fourth case, a single tube of Microreactors (statically mixed): flow is interrupted; Startup and shut- 5-mm dia. is used, and the cooling These typically have channel diam- down losses can be high jacket is at 10°C throughout. The eters of less than half a millimeter, al- Typical applications: Generally suit- overall reactor length is 509 m, and though channels of up to 1 mm or more able for small or large scale produc- the process material is progressively are often described as microreactors. tion with low viscosity fluids and lim- cooled to below 20°C The flow channel may be a simple tube ited mixing requirements; Generally The first case is the simplest and or may include static mixing elements better for dedicated applications since cheapest solution since the tube length to promote mixing. They operate under performance is sensitive to fluid veloc- is short and no cooling system is re- laminar flow conditions with a Reyn- ity (and therefore length has to suit quired. In the second and third cases, olds number of less than 100 [4]. the reaction time) the process temperature is controlled Advantages: Very good heat transfer; Tubular flow reactors with baffles within a range of 20°C but the second Good plug flow at low velocities; Can or static mixing elements (stati- case has the advantage of shorter tube handle reaction times from less than cally mixed): Baffles or static mixers length. In the fourth case, the product one second to many minutes within in tubes give better mixing and plug is subject to severe overcooling, which short channels; Low startup and shut- flow than simple tubes, and this im- will affect the reaction rate (and hence down losses; Can be used with very proves with increased density of mix- loss of yield). little process knowhow ing elements. Disadvantages: Generally poor mixing Advantages: Moderate to good heat Common flow reactors with two phase fluids, although this transfer depending on tube diameter; Most flow reactors fall into two broad can be addressed with static mixing el- Moderate to good mixing depending on categories according to whether they ements; Very high cost per unit volume; density of mixing elements and fluid use static or dynamic mixing. Poor solids handling capabilities and velocity; More flexible than simple • Static flow reactors rely on fluid easily blocked; Difficult to clean other tubular reactors in terms of reaction movement through the reactor to than by flushing; High pressure drop time for a given length; Can operate generate radial mixing and the Typical applications: Ideal for R&D effectively under laminar as well as higher the axial velocity, the better where limited quantities of reagents turbulent flow conditions subject to the mixing. Having no moving parts, are available; Can be used for low adequate density of mixing elements they can be fabricated with very throughput product for reaction times Disadvantages: Higher fabrication small channel diameters. They are of a few seconds or less cost than simple tubes; While perfor- generally smaller reactors suited to Tubular flow reactors (statically mance is improved with higher den- fast reactions with homogenous flu- mixed): These are simple tubes rang- sity mixing elements this is achieved ids (although multiphase mixtures ing from a few millimeters in diam- at the cost of higher pressure drop and can be handled in some cases) eter to over 50 mm. They rely on tur- increased difficulty of cleaning; Gener- • Dynamic flow reactors use mechani- bulent flow for effective mixing and ally poor solids handling capabilities cal stirring to mix the product. The plug flow. and easily blocked with high density mixing performance is independent Advantages: Moderate to good heat- mixing elements; On large diameter of fluid velocity through the reactor. transfer capacity depending on tube systems with high density mixing ele-

38 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 ments, hot spots can occur at the cen- Disadvantages: Poor performance for tubes without the cost and technical ter of the tube most applications due to the lack of problems associated with mechanical Typical applications: Suitable for a plug flow; Significant oversizing is re- seals, baffles and shaft stability. broad range of manufacturing op- quired to compensate for the high level Advantages: Good mixing that is in- erations, but preferably with clean of reacted material retained in the re- dependent of fluid velocity through fluids; For reasons of cost and pres- actor; Moderate to poor heat transfer the reactor; Good plug flow; High flex- sure drop, generally better suited to capacity depending on size ibility in terms of reaction time range reaction times of a few minutes or Typical applications: Only a small for a given tube length; Short, large less; Given the practical difficulties number of applications suit this type of diameter tubes that are easy to clean; of cleaning, generally better for ded- reactor. These are generally zero order Good handling characteristics for icated applications processes where reactor size is not a multi-phase mixtures. Very low pres- Oscillatory flow reactors (stati- significant cost factor and there are no sure drop (gravity transfer can often cally mixed): In static flow reactors, consecutive or competitive reactions be used) mixing relies on axial movement of Multiple, continuously stirred- Disadvantages: Subject to minimum fluid through the channel. The pen- tank reactors in series (dynami- diameter constraints, which limits the alty for this is high tube length and cally mixed): The lack of plug flow in scope for strong exotherms where good high pressure drop for processes with a single-stage stirred tank can be over- temperature control is required long reaction times. The oscillatory come by using multiple stirred tanks Typical applications: Processes with flow reactor addresses this problem in series. While as few as three tanks long reaction times, slurries and gas- using bidirectional flow. This gives in series have been employed by some liquid mixtures higher average velocities in short, users, a substantial improvement in larger diameter tubes even with long plug flow (in terms of residence time Conclusion reaction times. distribution) is observed by using ten The batch to continuous debate en- Advantages: Significant reduction stages [5]. Above ten stages, the trade- compasses a broad spectrum of views. in overall length compared to other off between cost and performance be- At one extreme are those who remain static flow reactors; Better solids comes increasingly difficult to justify. fully committed to batch methods. For handling characteristics than other For very small systems, agitated cell some applications batch reactors are static flow reactors; Moderate to good reactors that employ transverse mix- clearly a better solution or the only op- mixing; Generally more flexible than ing can be used. For larger systems, tion. Processes with sticky materials other static flow reactors in terms of conventional tanks with rotational for example are inherently unsuited residence time stirrers can be used. to flow systems as are some slurries Disadvantages: The additional vari- Advantages: Good mixing that is inde- with large solids. In the absence of able of oscillatory flow makes charac- pendent of fluid velocity through the heat transfer or mixing constraints, terization more difficult; Accumula- reactor; Good solids handling; Very batch reactors are also cheaper than tion of gas or vapor in the reactor can low pressure drop (gravity transfer flow reactors (although significantly severely impair mixing performance; can often be used) less energy efficient). The resistance Performance is a trade off between Disadvantages: Small systems are to change from batch to continuous good mixing (which favors short tubes) expensive due to the high number of is often justified on the grounds that and good plug flow (which favors long stirred stages required for optimum existing batch processes are well op- tubes); An additional pump is required performance; Large systems suffer timized and offer little scope for im- for the oscillatory flow; This has to from the same heat-transfer and provement. This is true for some pro- generate relatively high pressures mixing limitations of conventional cesses and particularly so when the and can present material selection batch reactors cost of switching from batch to con- problems with some process fluids Typical applications: Process devel- tinuous is factored in. Typical applications: Suited to a broad opment with multi-phase mixtures; Where there are mixing or heat range of slower reactions and can han- At the industrial scale, they are more transfer constraints however, the com- dle slurries common where volumetric capacities mercial benefits of flow reactors are Single, continuously stirred-tank of thousands of liters are required often clear cut and compelling. It has reactor (dynamically mixed): This Dynamically mixed plug-flow re- been suggested that as much as 60% is a conventional stirred tank with actors: Plug flow reactors need to be of commercially important non-poly- continuous feed and discharge. This long and tubular to achieve good plug mer reactions could be run more effi- is not a plug flow reactor, which se- flow. While rotating stirrers can be ciently in flow reactors [6] (and higher verely limits its suitability for most designed for use in tubes, they gen- if peripheral benefits are included). To applications. erally present significant cost and quantify these benefits, however, ac- Advantages: Good mixing that is inde- fabrication problems. An alternative count needs to be taken of many fac- pendent of fluid velocity through the design for agitated tube reactors uses tors that contribute to lower cost of reactor; Good solids handling; Very transverse mixing with free-moving goods. It also has to be recognized that low pressure drop (gravity transfer agitator elements (Figure 6). These most processes in use today were de- can often be used) generate strong radial mixing in long veloped for batch reactors and would

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 39 Feature Report

not necessarily be the first choice of in this field, the scope for integrating equipment, greater plant flexibility, method given the option of more-capa- multiple steps will improve, but as fewer batch failures, improved yield/ ble flow reactors. things stand, multi-step continuous quality, improved safety, lower energy At the other extreme of the batch processes will remain the exception costs and reduced solvent use. Prog- to continuous debate are advocates rather than the rule. ress in this area, however, will depend of fully continuous processes where The near term future for chemical on a broader understanding of the multiple steps are carried out within process technology must lie between subject in terms of methods for iden- a single process train. The difficulty the extremes of fully batch and fully tifying suitable applications for flow here is that good residence-time con- continuous [7]. There are many com- reactors, a better knowledge of the trol is critical to many flow processes. mon processes where incumbent available equipment and systematic Problems in one stage of a continuous methods are severely constrained by methods for process development. ■ process will impact the entire process heat transfer and mixing limitations. Edited by Dorothy Lozowski train, and the system will only be as Integrating flow reactors within exist- good as the least reliable step. As pro- ing batch processes for the right ap- Author Robert Ashe (AM Technology, cess equipment and knowhow develop plications will contribute to: smaller The Heath Business & Tech- nical Park, Runcorn,Cheshire, References WA7 4QX, U.K.; Phone: +44 (0) 1928.515454; Email: 1. Nichols, J., Innovations in Process Technol- 5. Levenspiel, O., “Chemical Reaction Engineer- [email protected]) ogy for Manufacture of APIs and BCPs, ing”, 2nd Ed., John Wiley and Sons, 1972. is a chemical engineer with Pharm. Eng., Vol. 28, No 5, Sept./Oct. 2008. 6. Calabrese, G.S. and Pissavini, S., From batch over 35 years of experience in 2. Levenspiel, O., Bischoff, K., “Backmixing in to continuous flow processing in chemicals fine chemicals, pharmaceuti- the Design of Chemical Reactors” Vol. 51, manufacturing, AIChE J., Vol. 57, No. 4, cals and food manufacturing. Dec. 1959. pp. 828–834, 2011. Much of his career has been devoted to chemical plant de- 3. Eslinger, J., De Dietrich Process Systems, 7. Roberge, D.M. and others, Microreactor Tech- sign in high-value chemical manufacturing. In Bulletin BP 8, F-61170, Sept. 28, 2004. nology and Continuous processes in the fine 2000, he co-founded AM Technology with David 4. Capretto L. and others, “Micromixing Within chemical and pharmaceutical Industry: is Morris. This company specializes in the manu- Microfluidic Devices, Topics in Current the Revolution Underway?, OPRD, Vol. 12, facture of flow reactors and holds a broad portfo- Chemistry”, Vol. 304, pp. 27–68, 2011. pp. 905–910, 2008. lio of patents for dynamic mixing in tubes.

Circle 1 on p. 60 or go to adlinks.che.com/40272-01 40 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Solids Processing Blending, Sampling and Segregation These aspects of dry solids mixing represent three sides of the same coin. Do not discount them

Thomas G. Troxel Jenike & Johanson, Inc.

lending and segregation are melt index and so on. Blend- two opposite and competing ing bulk solids can be achieved processes in solids handling in many ways including batch Bthat ideally fit the expres- and continuous methods and sion “two sides of the same coin.” But, with a wide variety of equip- if you think about it, coins have three ment, covering the range from sides and sampling completes the idi- extremely low intensity blend- omatic expression perfectly. Blending ing with gravity recirculation is a necessary and essential process or layering components onto a operation widely employed in many belt, to high intensity blending industries and materials, from nano- with high-speed, high specific- FIGURE 1. This pattern shows how the faster scale powders to run-of-mine ores. horsepower blenders. velocity in the center displaces material relative Segregation is almost always an un- All of the various equipment to the slower material at the walls wanted consequence of handling op- and processes for blending sol- erations that reverses the blending ids rely on three principal mechanisms sufficient to locally fluidize material, process or creates a need for blending for achieving a blend: convection, dif- diffusion occurs. Tumble blenders, where it might not otherwise be nec- fusion and shear. continuous screw blenders and agi- essary if it were not for the effects of Convection. Convection is the trans- tated blenders also provide opportu- segregation. Sampling is the vitally fer of a collection of particles from one nities for diffusion where material is important tool for measuring and location to another. This can occur as a cascading or in free-fall. quantifying a blend, understanding result of material cascading in a tum- Shear. The definition of shear as it the sources and effects of segregation ble blender, material moving against applies to solids blending is some- and for troubleshooting problems. the blade of a ribbon or paddle blender times misunderstood. Shear occurs in or as a result of gas pressure pulses in a flowing granular solid as a result of Blending a pneumatic blender. a velocity gradient, and can develop Blending is the process of combining Diffusion. Diffusion is the random as either a discontinuous shear (for two or more materials to achieve a redistribution of particles that occurs instance, a shear or slip plane) or as combined product. The mixture may as a result of increased particle mobil- a continuous gradient of velocity. In be a combination of dissimilar materi- ity. Increased mobility typically occurs either case there can be some over- als such as cement, sand and aggre- when the bulk density of the material lap in what could be called shear and gate to make concrete; or cereal flakes, is decreased sufficiently to allow in- what might be characterized as con- raisins, nuts and marshmallows to dividual particles to move relative to vection. The important difference, at make breakfast cereal. A blend may one another. Fluidization in fluidized least as it applies to solids blending, also be a combination of chemically bed reactors or granulators results in is in the intensity. Shear planes that similar particles blended to create a diffusion. Mechanical blenders move develop in gravity blending or in a uniform mixture of particle sizes, or collections of particles by convection, tumble blender or screw blender will another property such as color, flavor, but when the speed of the agitator is achieve blending predominantly by a

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 41 Solids Processing

convective process. Shear in a high- ponent and allowable speed mixer will have a different end variation) but also the result in that it will be much more quantity of material effective in breaking up agglomer- that is to be measured. ates of fine powders and distribut- The compositional re- ing small-particle-size material with quirement of a blend high surface activity. is usually well known Figure 1 is a cross section view because it is either the through a bin showing the displace- entire objective of the ment of material as it flows. The pat- process to produce a tern shows how the faster velocity in particular mixture, such the center displaces material relative as a pharmaceutical FIGURE 2. Sifting segregation occurs when a mixture containing a range of particle sizes is allowed to form to the slower material at the walls. tablet or box of cereal, a pile. Smaller particles sift between larger particles as This displacement pattern can be or it is an intermediate each layer of material slides along the pile surface described as shear deformation, but mixture that has well the blending that occurs is caused by defined requirements. Determining selected by the packaging system convection of collections of material the amount of material to measure is controller, to control both the propor- from the central part of the bin that sometimes less clear, and may be dif- tion of each component and the total reach the outlet sooner than material ferent depending on who is answering weight in a box. This would seem an near the wall. If material withdrawn the question. In pharmaceutical ap- ideal solution since it would guaran- from the bin is circulated back to the plications the answer is clear in that tee both accurate package weight and top, the discreet fill pattern that was it is almost always based on the unit composition. From the producers point placed into the bin will be smeared dose of the blend that makes up the of view, they had improved quality by and homogenized, and some degree of final tablet. insuring that every package met their blending will be achieved after several In other applications the sample quality standard. recirculations [1]. size subjected to scrutiny is not as However, to everyone’s surprise, In a high-speed agitated blender, clear cut. Take, for example, a box consumer complaints from packages shear occurs with significantly higher of cereal. In one specific example a produced at this plant went up. What intensity near the agitator but affects manufacturer produced a cereal with the plant had gained in compositional a relatively small volume of material. a cereal particle and a marshmallow accuracy they had sacrificed in unifor- The high-intensity shear can break candy particle. The packaging line mity. Consumers found that individual agglomerates, plate fine particles onto filled boxes from a series of conveyors bowls of cereal poured from the new the surface of larger particles and re- that fed a mixture of the two compo- packages had much wider variations of distribute particles with much higher nents into a gravimetric packaging the two components than boxes filled intensity, causing better diffusion of machine that dispensed the required from the old filling line. The new fill- small particles that may adhere to weight of the blend into each package. ing line had given up control of blend- themselves or other particles. Ideally, The two components of the mixture ing, even though the blending in the the convective component of blending were of similar size and density and old system was very “low tech”. The in this type of blender brings all of the the only blending that occurred was new system allowed only about one material in the blender into the high in the handling system along several second from the time the ingredients shear zones. conveyors and in a surge hopper. Each were separate until they were com- component was metered onto the con- bined in the package. There was very Blend quality veyor system at the correct ratio, but little opportunity to do any blending, In casual conversation, terms such as there was not a discreet blending pro- and the result was that some boxes “uniform blend”, “homogenous mix- cess. The manufacturing plants fine were well blended while others were ture”, and “well blended” are often tuned their systems to get an accept- segregated. From the manufacturers used without quantifying what they able mixture into each box. point of view, they had “improved qual- mean. In the heavily scrutinized phar- In this case, each box was always ity” and were taking responsibility for maceutical industry, regulations and within weight tolerance for the stated what they could control to the highest guidelines dictate specific and often package quantity, but there was no degree of precision, but they were not rigorous methodology for quantifying direct control of the ratio of the two controlling the sample size of interest the uniformity of a mixture. Food and components in any box. In an effort to to consumers. other consumer products must also improve quality, a new packaging line Random blend. The simplified case meet trade regulations for delivering was installed that handled each com- of blending two different ingredients the stated quantity of product and ponent individually up to the packag- that do not have significant bonding composition of ingredients. Quantify- ing head where each component was or other interactions is often referred ing the structure of a blend requires weighed in a series of weigh hoppers, to as a random blend. In a random defining not only the composition (for and then each box was filled from blend, all individual particles are free instance, the proportion of each com- several hoppers of each component, to move relative to each other, and

42 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Discharge from V blender 30.0

25.0

20.0

15.0 % Beads 10.0

5.0

0.0 0 20 40 60 80 100 Material emptied, %

FIGURE 3. In the example described in the box on p. 44, cy FIGURE 4. Implementation of a morerigorous sampling lindrical pellets with a nominal size of about 3 mm were being method in the example on p. 44, revealed inadequate blending. blended with nearly spherical beads with a size range from Area between dotted lines represents desired blend ratio about 1 mm down to 150 microns particle bonding is very weak or does Segregation not occur. Particles that form random Segregation is the separation of par- blends can be easy to blend, because ticles that have identifiable differ- the particles move easily relative to ences. By definition, identical parti- one another, but that also means that cles cannot segregate. Segregation can they can readily separate from each be driven by many forces including other and collect in zones of similar gravity, electrostatic forces, fluid drag particles when forces such as gravity, forces and elastic forces. airflow, or vibration act on the blend. Sifting. The most prevalent type of This process is referred to as segrega- segregation is sifting, which results tion. Random blends are never perfect, in separation by particle size. Sift- and even in the best-blended state ing segregation occurs to some de- there will be random variations in gree in virtually every industry that concentrations of components. handles bulk solids. Sifting will occur Ideal random blends are uncommon in mixtures of different size particles in most industrial applications, al- when particles are sufficiently large though the cereal example described so that surface forces are weak above comes close. In most dry blend- relative to gravity (usually larger ing applications, particles have some than 100 microns), when particles FIGURE 5. Based on the improved tendency to interact with one another have mobility relative to one another sampling results, the example blender by way of chemical, molecular, physi- (in other words, they do not adhere to was modi ed to improve the blending cal, or other means such that individ- each other) and when there is some performance and minimize segregation mechanisms ual particles can agglomerate, coat or mechanism to allow particles to move bond to one another. When particle relative to one another. Collections of tion by size may occur. Even if all the interaction occurs, the blend is re- different size particles will not spon- particles are chemically homogeneous, ferred to as an ordered, structured, or taneously segregate when at rest, but this segregation may cause problems interactive blend. In an ideal world, will often readily segregate when al- because it may affect other blend prop- this type of blending process could lowed to move in many common, in- erties, such as solubility or bulk den- create new particles, each consisting dustrial handling processes. sity. There are many examples where of the combined individual ingredi- Figure 2 shows an example of sift- this type of segregation is important, ents. A perfect particle created in this ing segregation that occurs when a such as with spray-dried laundry de- blender would consist of the desired mixture containing a range of particle tergent and food products, and other ratio of each ingredient. This concept sizes is allowed to form a pile. Smaller natural materials such as clay cat lit- of combining ingredients to create particles sift between larger particles ter, coal and other mineral materials. new, chemically homogeneous parti- as each layer of material slides along In these examples the particles vary cles is one of the primary objectives of the pile surface. As the pile builds up, in size, but are virtually identical from wet and dry granulation processes. In the finer fraction deposits preferen- a chemical standpoint. most industrial blending processes, tially near the center and coarser frac- In many other industrial-blending the reality is somewhere between a tion near the edges. applications, particles not only dif- random blend and an ordered blend. A blend of perfect structured par- fer in size, but also in chemical com- Some particles of the blend may have ticles of identical size will not segre- position. And in most cases, particles very little tendency to interact while gate after discharge from the blender. of different size also have different other blend components may have However, if there are size differences chemical composition, so sifting seg- significant interaction. between the particles, then segrega- regation not only results in physical

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 43 AN EXAMPLE

n an example involving plastic compounding, engineers for the free flowing and hence blend easily. Blend time in the tumbling Iproject had experience using a V-type rotating blender for simi- type blender is very short, on the order of tens of revolutions. lar materials at other plants. Batch ingredients would be fed into However, the other side of the coin is equally important because a scale hopper and then discharged into the blender. The blended the material also segregates readily, so maintaining the material batch would then be discharged into a surge bin feeding an ex- in a blended state is difficult. This required two modifications to truder. While this process had worked successfully at other com- the geometry of the blend container. First, the dead zone near pounding plants, this plant would blend ingredients with a wider the center of the blender had to be reduced because the blender size range. The most extreme case involved blending the two ma- geometry did not allow enough diffusion to mix material in the terials shown in Figure 3, which consisted of cylindrical pellets with center of the blender. Convection dominated the action in the a nominal size of about 3 mm and nearly spherical beads with a blender, and diffusion occurred on the cascading surfaces, but size range from about 1mm down to 150 microns. some material remained poorly blended in the center. In addition Engineers for the project ran tests in a small-scale V-blender and to the blending performance, the flow pattern that developed dur- evaluated blend uniformity by taking samples from the blender. ing discharge had to be changed from funnel flow, where some The overall blend results showed a lot of scatter. Some samples of the blend remained stagnant during discharge, to mass flow, were acceptable, while others were significantly outside the de- where all of the blend flowed as it discharged. In funnel flow, the sired blend ratio. Engineers also noticed that when the batch was highly segregating material could de-mix along shear surfaces discharged after a test, the material in the receiving container during discharge. A mass flow pattern was achieved by design- was severely segregated. This prompted development of a more ing a sufficiently steep hopper-shaped blend container with an rigorous sampling method that included collecting samples from internal bullet to displace material in the center of the container. the discharge of the blender from beginning to end. When this The final configuration of the blender, shown in Figure 5, pro- was done the results, shown in Figure 4, clearly showed inad- duced the results shown in Figure 6. equate blending. Based on this realization, further testing was The other important point illustrated in this example is sampling. done to determine if a tumbling type of blender could be used. Without sampling the blender discharge stream from start to fin- After a series of trials, a cylindrical blend vessel with an conical ish, it would be impossible to know if the blend delivered to the hopper and insert was found to produce a blend within specifica- extruder would be uniform and within specification. tion, and discharge a blended stream to the downstream vessel. A blending process shouldn’t be considered as an independent This example illustrates several key points about blending, seg- step in a block diagram, but really must be treated as a synergy regation and sampling. First, the blender must provide the cor- of the mixing activity, segregation and sampling to produce the rect blending action for the solids. These two materials are very desired end result. ❑ property differences associated with FIGURE 6. The size distribution, such as bulk density sampling results Optimized Blensert blender for the new blender 30 and fluidization behavior, but also dif- design show the ferences in chemical composition. improved perfor- Fluidization segregation and mance. Area be- 25 particle entrainment. Other com- tween dotted lines mon mechanisms of segregation that represents desired blend ratio act primarily on particle size are flu- 20 idization segregation and particle entrainment or dusting segregation. 15 Fluidization segregation occurs where gas movement through a bed of solids % Beads 10 causes finer, lighter particles to rise to the top surface of a fluidized blend of powder, while the larger, heavier par- 5 ticles concentrate at the bottom of the bed. Particle entrainment or dusting 0 segregation occurs when fine particles 0 20 40 60 80 100 in a blend are carried by air currents Material emptied, % (such as during transfer of a blend into a container) and then settle pref- erentially at the container walls. blend uniformity. Variability can be ex- the sampling method. The two “golden pressed by statistical measures, such as rules” of sampling are to always collect Sampling standard deviation, coefficient of varia- a full stream sample, and always collect Sampling is essential in determining the tion, or relative standard deviation, as a sample while it is moving [3]. state of the blend in a blender, in down- well as other measures [2]. In the case of the cereal example stream equipment or in the final deliv- The single most important rule of given above, sampling is easy because ered product. Samples are analyzed to sampling is to collect a sample that the sample is either a whole box of ce- measure the variables of interest to the accurately represents the state of the real or individual servings poured from application, such as particle size, chemi- blend at the point where it is sampled. the box. In either case the sample is cal composition, pH, dissolution rate, In many industrial processes this is a easy to get and it is possible to analyze color and so on. The overall average of significant challenge due to either the the entire sample. For other processes, the sample results represents the aver- difficulty of getting a sample at the de- significant challenges can prevent age composition of the blend. Variations sired location or because of the potential the use of good sampling techniques. between samples provide a measure of for sampling error that is introduced by In an example involving limestone

44 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Solids Processing

at a circulating fluidized-bed boiler, rotated to exposed the cavities, blended error. These can come from properties of the size distribution of the limestone material will fill the cavities, which can the blend and from operator technique. used for fluegas desulfurization came then be covered again and withdrawn. Some typical sources of error include into question. This became a critically Thief sampling has been used exten- local segregation as material fills the important question because the plant sively and studied thoroughly. While it cavities, smearing as the thief is in- could not meet emission regulations remains the only practical way to collect serted into the bed, and preferential ad- above about 50% output, and the blame samples from all positions in a static hesion or repulsion of some components was falling on the size distribution of bed, it has been shown to have biases of the blend. the limestone produced by the onsite and limitations that can cause sampling Sampling will always introduce preparation plant. The plant produced about 50 ton/h of limestone, and to get a meaningful sample was not a trivial task. To satisfy all parties involved, the plant had to modify its chute systems to put in large diverter gates and posi- tion several operators to coordinate the Vanton solid thermoplastic pumps to stainless, collection of simultaneous full-stream high alloy, plastic-lined and fiberglass pumps for water, samples in 55-gal drum quantities. wastewater and corrosive treatment chemicals: Samples of this size pose another challenge in analysis. Usually it is not practical or convenient to analyze such large sample quantities, so samples must be reduced or split. Simply grab- bing a small sample from a large sample container can introduce significant sam- • ZERO CORROSION pling error, especially if sifting segrega- (unlike stainless and alloys) tion can occur. The preferred method of • ZERO CONTAMINATION splitting samples is to use a spin riffler, (unlike stainless and alloys) which can divide a sample into a num- • ZERO CHEMICAL ABSORPTION OR WICKING ber of smaller splits, usually from 6 to (unlike fiberglass reinforced 16 divisions. Spin rifflers are capable of plastics) providing a high degree of uniformity • ZERO TEARING, CRACKING, between the individual sub-samples. OR PEELING Another challenging task is sampling (unlike plastic linings) All wet end components of Vanton from a static bed in a blender. Clearly • ZERO OR NEAR-ZERO ABRASION centrifugal pumps are molded of solid PVC, (unlike stainless, alloys, and fiberglass) PP or PVDF, and handle flows to 1450 gpm these samples cannot be collected while (330 m3/h), heads to 400 ft (122 m) and the material is moving, so some means temperatures to 275°F (135°C). of getting a meaningful sample must Vanton molds all wet end components of It means you can say good-bye be used. Simply scooping material from solid, homogeneous thermoplastics that to pumping problems you now the top surface is insufficient for many are 100% inert to the caustic and acidic experience with chemical transfer, treatment chemicals you handle, such disinfection, dosing, effluent reasons, including particle segrega- as alum, ferric chloride, hydrofluosilicic collection, lift stations, odor control, tion, which could make the top surface acid, polymer, sodium hydroxide, sodium recirculation and other process significantly different from material hypochloride, sulfuric acid and others. applications. deeper in the bed. A sampling thief is often used to collect samples from a sta- tionary bed. A sampling thief is a probe that can be inserted into a bed of material to col- lect a sample from below the surface. SUMP-GARD® Vertical CHEM-GARD® Horizontal FLEX-I-LINER® Rotary Non-metallic Many designs exist, but in their basic Centrifugal Pumps Centrifugal Pumps Peristaltic Pumps Pump/Tank Systems form, they consist of a rod, frequently Standard, bearingless, Standard, ANSI, DIN, Dosing/feeding liquids Tanks from 60 to 5000 gal low headroom, wash mag drive, close coupled and viscous fluids (227 to 18,900 liter) with with a pointed tip. The rod has cavi- down, integral motor/ and self priming to 6000 SSU pumps and automated ties cut into it along its length which shaft and vortex controls Z-0551 are covered by a tube that fits closely over the rod and has openings that cor- respond to the cavities in the rod. The .com tube can be rotated to cover the cavities 1-908-688-4216 [email protected] or open them. When the rod is inserted into the bed of material, and the tube Circle 23 on p. 60 or go to adlinks.che.com/40272-23 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 45 Solids Processing

some degree of error, which can affect propriate location, such as a known terial may have been stagnant during the sampling results in three ways. dead zone in the blender that may be blending and at the beginning and end Perhaps the most common effect is holding the “missing” material. When of discharge from a batch bin. ■ that sampling increases the variability this type of error is observed it usually Edited by Rebekkah Marshall of samples, which produces data show- requires additional detective work to ing that the uniformity of the blend is determine the cause of the bias. References worse than it actually is. In some cases, Sampling devices can also produce 1. Carson, J.W., and Royal, T.A., Techniques of this presumed “fact” is used to suggest samples that show lower variabil- in-bin blending, IMechE, C418/056, 1991. 2. Fan, L.T., Chen, S.J., and Watson, C.A. Solids that a blend is actually better than ity than are actually present due to mixing. Industrial Eng. Chem. 62, 53–69, July what the sampling data shows. smearing of the sample. This type of 1970. Author Sampling error can also produce error is often referred to as “counter- Thomas G. Troxel is a vice bias, or an overall shift in the results, feiting.” Counterfeiting is hard to de- president at Jenike & Johan- indicating that the measured average tect because it may produce results son, Inc. (3485 Empresa Dr., San Luis Obispo, CA 93401; from the collected samples is higher that show blending is good. Phone: 805-541-0901; Email: or lower than the known blend com- The purpose of sampling is to ac- [email protected]). He holds a B.S. in Engineering Science position. This type of error can be con- curately quantify the state of a blend (ES) from California Polytech- nic State University (Cal Poly) founding because people often jump or uncover blend quality issues, not to in San Luis Obispo. After to the conclusion that there is “miss- mask or overlook suspected problems. graduating as the Outstand- ing Senior in the ES program ing” or “extra” material, somehow. Samples should be intentionally col- in 1981, he worked at General Dynamics Co. He It is more likely that one component lected from suspected regions where then helped to open Jenike & Johanson’s San Luis Obispo, California facility in 1982. Troxel adheres to, or is repelled by, the thief, the blend may be less uniform, not just has been intimately involved in many aspects of or preferential flow of one component from the middle of the blender, or dur- the firm’s consulting and research activities on a wide range of projects including flow properties into the thief shifts the sample com- ing the “best” part of a production run. testing, modeling, blending, pneumatic convey- ing and fluidization. He has been a major force position. Another possibility is that Fringe regions may include the surface behind the firm’s expansion in mechanical design a sample is collected from an inap- of the material, regions where the ma- engineering and custom-built equipment.

Circle 10 on p. 60 or go to adlinks.che.com/40272-10 Environmental Manager

Stanley S. Grossel Process Safety and Design Reduce Hazards in Consultant Process Vacuum Systems acuum conditions for many Reduce explosion risks, and chemical unit operations — including distillation, evaporation, dry- and physical hazards, to ensure safer operation Ving, crystallization, filtration and more — are typically achieved of vacuum pumps and related systems using the following three approaches: • Steam ejector systems rials. Each of these chemical sources medium- and high-vacuum systems. • Mechanical vacuum pumps of hazards is also discussed below. Consideration should be given to the • Integrated vacuum systems (which Homogeneous reactions. Homogeneous fact that gases that do not normally combine steam ejectors and me- reactions occur in the gas phase be- come into contact with each other dur- chanical vacuum pumps) tween two or more gas molecules. If ing the process cycle may be mixed in This article is the second part of a such reactions are possible in a given the pumping system and exhaust pip- two-part series,1 and provides practi- manufacturing process, the process ing. It is possible that water vapor or cal guidance for addressing — during pressure and reactant concentrations cleaning solutions may be present in design and operation — some of the must be carefully controlled to pre- the process equipment after routine most commonly encountered hazards vent excessive reaction rates. maintenance procedures due to the and maximizing the overall safety of Heterogeneous reactions. Heteroge- equipment having been washed and these systems. neous reactions require a solid surface cleaned. Water vapor may also enter This section reviews the potential (a catalyst) to occur. Most heteroge- the system from exhaust ducts and hazards that can occur with process neous reactions become homogeneous exhaust scrubbers.Where solvents are vacuum pumps and systems. These at higher pressures, normally at pres- used to flush process deposits from the include chemical sources of hazards, sures well below atmospheric pressure. vacuum system, it is important to en- explosion-related hazards and physi- This means that the way in which the sure that the selected solvent is com- cal sources of hazards. They are dis- gases react inside the process equip- patible with all the process materials cussed below, and are based on mate- ment will not necessarily relate to the in the vacuum system. rial in Reference 1. way that they react when compressed by a mechanical vacuum pump. Explosion-related hazards Chemical sources of hazards Abnormal reactions. Abnormal reac- Explosions can occur in vacuum Chemical reactions and explo- tions can occur when chemicals come pumps. The most common causes of sions. All possible chemical reactions into contact with gases or materials violent rupture of a vacuum system that a vacuum system might encoun- that the designer did not anticipate. due to an explosion results from the ter at any point in mechanical vacuum This can occur, for example, when ignition of flammable materials, or the pump systems should be considered — there is a leak that either allows atmo- blockage or restriction of the pump ex- particularly those that could result in spheric gases (air) to leak into the sys- haust. In general, the source of explo- a fire or explosion (deflagration). And tem, or toxic, flammable, or explosive sion hazards in vacuum systems fall such an analysis should consider these gases to leak into the atmosphere. into one of the these categories: scenarios during normal use, potential To prevent the occurrence of abnor- • Oxidants misuse and failure conditions. mal reactions, high-vacuum applica- • Flammable materials For instance, experience has shown tions should typically maintain a leak • Pyrophoric materials that explosions have occurred in situ- tightness of 1 × 10–5 mbar-L/s (1 × • Unstable materials ations involving materials that were 10–3 Pa-L/s), or lower. It must be en- Oxidants. Oxidants, such as oxygen, not originally considered by the sys- sured that all valves in the system are ozone, fluorine and others are often tem designer, and in which the failure leak-tight across their seats. pumped using vacuum pumps. Oxi- mode of that particular scenario had In estimating an acceptable air- dants readily react with a variety of not been taken into account. During leakage rate, do not overlook the im- substances and materials. The reac- this analysis, the reactions that should plications of process contamination tion often produces heat and an in- be considered include homogeneous, by air leakage. If leakage into the creased gas volume with a potential heterogeneous and abnormal reac- vacuum system could in any way ad- for fire and overpressure in the pump tions. Two other sources of chemical versely affect the process, or create a or exhaust system. The practices dis- hazards are toxic and corrosive mate- safety hazard, the acceptable air leak- cussed below are recommended to age may be considerably less than minimize the potential for an explo- 1. Editor’s note: Part 1 of this two-part article ap- peared in the September 2012 issue (pp. 59–66). that presented in Ref. 1, pp. 83–86, for sion in pumps handling oxidants:

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 47 Environmental Manager

1. Always use perfluoropolyether in contact with air anywhere in the gas to below its toxic limit (PFPE) lubricant in pumps that are vacuum system. This can happen if • Leak detection: Many vacuum pumps used to pump oxygen in concentra- air leaks into the system, or if the sys- are generally designed to be leak tions above 25 vol.% in an inert gas. tem exhaust comes in contact with the tight to a level of < 1 × 10–3 mbar- Although PFPE lubricants are pre- atmosphere. In a confined space (such L/S (< 1 × 10–1 Pa-L/s). However, ferred, hydrocarbon-based lubricants as an exhaust duct, a dust filter, or an the leak-tightness of the adjoining may be used if a suitable inert purge oil box of a mechanical pump) combus- process system cannot be ensured is used to guarantee that the oil is not tion can cause an explosion. and thus should be checked with a exposed to unsafe levels of oxidant. If, in addition to pyrophoric materi- reliable leak-detection method (such 2. If it is not desired to use PFPE lu- als, an oxidant is also present in the as helium mass-spectrometry leak bricants in oil-sealed rotary vane or process, the probability of an explosion detection) to confirm the integrity of piston vacuum pumps, dilute the oxi- occurring at both atmospheric and pro- the vacuum and exhaust systems dant to a safe concentration using an cess conditions increases greatly. Simi- • Shaft sealing (dry pumps): Many inert gas (dry nitrogen). However, this larly, if oxidants from other processes vacuum pumps use a gas purge to approach is only feasible for relatively are vented through a common extrac- ensure that process gases do not low flowrates of oxidant gases. tion (treatment) system, combustion or enter the gearbox, and thereby, po- 3. One must install safety features in an explosion could result. It is neces- tentially escape into the atmosphere. a mechanical pump system to ensure sary, therefore, that an independent The integrity of the purge gas sup- that the minimum flow of the dilution extraction system be used when pyro- ply must be ensured when handling gas required to reduce the oxidant phoric materials are pumped. toxic gases. Non-venting regulators concentration to a safe level is always While the use of PFPE lubricants in must be used in combination with a available, and to ensure that the flow the pump will not prevent the ignition non-return check valve of oxidant does not exceed the maxi- and explosion of pyrophoric materials, it • Shaft sealing (other pumps): Oil- mum allowed flowrate. The safety sys- will help to minimize the risk of a sub- flooded shaft-seal designs (for in- tem must be designed so that the flow sequent oil fire. However, PFPE lubri- stance, for mechanical booster pumps of oxidant stops immediately if these cants can absorb process gases which, and rotary vane pumps) minimize conditions are not met. in the case of pyrophoric materials, can the risk of process gas leakage (or, of Flammable materials. Many gases lead to local ignition when the lubri- the in-leakage of air), and can pro- are flammable and can explode (defla- cant is exposed to air. The probability of vide a visual warning (oil leakage or grate) if they are within the flamma- this occurring can be reduced by using oil level reduction) before a hazard bility limits, and there is an ignition a dry vacuum pump, which contains no arises. Other seal designs may not source of sufficient energy available lubricant in the swept volume. give adequate warning of failure (for instance, from a localized heat Unstable materials. Sodium azide is • Magnetic drives: Where total her- source). It may be possible to reduce occasionally used in the preparation of metic sealing is required, dry vac- the explosion hazard if the concen- products for freeze drying and other uum pumps can be fitted with a tration of flammable gases is lowered manufacturing processes. Sodium azide magnetic drive employing a ceramic by introducing an inert gas at several can produce hydrozoic acid, the vapors containment vessel (housing); this points within the pump or system. of which can react with heavy metals to eliminates the need for shaft sealing Another way to reduce the probabil- form unstable metal azides, which may on the motor input shaft ity of an explosion is to eliminate po- then explode spontaneously. If pressure-relief valves or rupture tential ignition sources. It may be dif- Brass, copper, cadmium, tin and zinc disks are used to relieve excess pres- ficult to eliminate all ignition sources are commonly used in many compo- sure, ensure that they are safely because there is often a possibility of nents in vacuum pumps, accessories vented into a suitable exhaust system static discharge or friction hot spots and piping. If one’s process system uses to prevent the toxic gas from escaping where rotating machinery is used. or produces sodium azide, it must be en- into the atmosphere and possibly com- Where it is not possible under abnor- sured that the gas path in the process ing in contact with people. mal conditions to avoid the flammable system does not contain heavy metals. Corrosive materials. Corrosive gases zone, the equipment must be designed Toxic materials. Toxic materials are generally attack the material they are to contain any resulting explosion not necessarily explosive in nature, but in contact with by the mechanism of without rupturing or transmitting a they are hazardous to one’s health, and ion exchange, a process that can only flame to the environment. This is typi- thus require special care. The following happen in the presence of a suitable cally achieved by installing a flame ar- methods for handling them in vacuum liquid solvent (such as water). This rester on the exhaust piping. pump systems should be considered: mechanism cannot occur when the Pyrophoric materials. A number of • Gas dilution: Systems can be in- material is in the vapor phase, even if gases (such as silane, phosphine and stalled to allow the dilution of toxic a suitable solvent is present. others) are pyrophoric — that is, they process gases as they pass through The possibility of corrosion occur- are spontaneously flammable in air at the vacuum pump and into the ex- ring in mechanical vacuum pumps atmospheric pressure, so combustion haust piping. Dilution may be used should be considered when carrying could occur if the gases were to come to reduce the concentration of the out a hazard analysis.

48 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Edwards Vacuum Pumps

sure of a deliberately closed and iso- lated vacuum system cannot occur, for instance, as a result of a fault in a pressure regulator or purge con- trol system • Where the pumped product can react FIGURE 1. Prudent design, operating and maintenance strategies are needed to violently with water, it is recom- minimze the potential hazards associated with all types of vacuum systems mended that a cooling fluid other than water (for example, a heat transfer Many vacuum pumps are not de- items listed below to ensure safe opera- fluid) be used in the cooling circuit signed to resist wet corrosive mate- tion of vacuum pumps and systems: rials. Therefore, the following points • Consider all possible chemical reac- Physical sources of hazards should be considered: tions within your system Exhaust system over-pressure. The • Anhydrous materials: The removal • Make allowance for abnormal chem- most common physical hazard is an of a liquid solvent (water) will pre- ical reactions, including those that over-pressurized exhaust due to a vent corrosion. However, special could occur under fault conditions blockage or restriction in the exhaust care must be taken to prevent the • Refer to material safety data sheets system. All high-vacuum pumps are ingress of wet air from the exhaust when you assess the potential haz- specifically designed to operate with of the vacuum pump, especially ards associated with your process high outlet-to-inlet compression ra- when the pump is stopped and air materials tios. They are designed to exhaust to is sucked back into the pump. An • Use dilution techniques to minimize atmospheric pressure, or to a pressure inert purge should be used as part reactions with oxidants and flam- only slightly higher. If the exhaust is of the shutdown procedure in order mable materials restricted or blocked, many typical vac- to flush corrosive vapors out of the • Use dry vacuum pumps if flammable uum pumps can generate an exhaust system prior to shutdown materials could enter the flammable pressure in excess of 7 barg (101.6 psig). • Dilution: Use a suitable dilution gas zone under abnormal conditions This can lead to failure of the pump or to prevent condensation of corrosive • Use the correct type of lubricant in other components in the system. vapors and thus prevent the pos- your pump when you pump oxidants, In addition to the potential over- sible resulting corrosion and consider the use of a dry pump pressure caused by the operation of • Temperature: Increase the pump- • Do not use heavy metals in the gas the pump, the introduction of a com- and exhaust-line temperature to path of your system if your process pressed gas (such as a purge or dilu- prevent condensation and, therefore, uses or produces sodium azide tion gas) can also over-pressure the corrosion. Where the low tempera- • Take specific care when handling system if the exhaust system is re- ture of the incoming gas flow could toxic, corrosive, or unstable materials stricted or blocked. lead to condensation and subsequent • Ensure that the concentration of Where a vacuum pump is fitted with corrosion, an inert gas purge should flammable materials in the vacuum a flame arrester on the exhaust side, it be used to avoid condensation system does not permit these mate- is essential that the exhaust back pres- • Corrosion of safety equipment: Where rials to enter the flammable zone. sure does not exceed the maximum safety critical equipment (such as During operation, there should be limit stated in the vacuum system's flame arrester elements, tempera- a suitable supply of inert gas (ni- instruction manual. A regularly sched- ture sensors, safety relief valves and trogen) to achieve dilution to a safe uled maintenance program should be so on) could be damaged by corrosive level under all foreseeable operating instituted to ensure that process de- products in the process gas flow, their conditions and failure modes posits do not block the exhaust system materials of construction must be se- • Ensure that exhaust blockages can- and flame arrester. In addition, it may lected to avoid this hazard not occur during operation, either be desirable to install a pressure sen- • Phase changes: Unplanned phase because of mechanical components sor located between the pump and the changes can result in condensation (such as valves or blinds) or because flame arrester to detect if a blockage is and possible corrosion. Consideration of process materials or byproducts occurring and to sound an alarm. of changes in temperature and pres- depositing in pipelines, filters and Phase change. Another cause of sure is required to avoid this hazard other exhaust components overpressure is sublimation or phase • Unplanned reactions: These can lead • Use only PFPE (perfluoropolyether) change, which can lead to blockage of to the generation of corrosive prod- oils to lubricate pump mechanisms process piping. The instruction manual ucts. Careful consideration should that are exposed to high concentra- supplied with a vacuum pump should be given to the possibility of cross tions of oxygen or other oxidants. be read for information on the maxi- contamination when equipment is Other types of oils sold as “non- mum and recommended continuous used for more than one purpose flammable” may only be suitable for backpressure, and the exhaust system To minimize hazards from chemical use with concentrations of oxidants should be designed so that these limi- sources and to minimize explosion haz- up to 30% v/v tations can be met. ards, attention should be paid to the • Ensure that the accidental overpres- Some recommendations for oil-

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 49 Environmental Manager

sealed rotary vane and piston pumps, there is no process gas flow through Where the vacuum system is used to dry pumps, and exhaust system design the system. These two methods can handle a vapor or gas mixture in the are summarized below: help to prevent over-pressurization: flammable range, and where there is • For oil-sealed rotary vane and piston • Reduce the pressure and allow the a potential ignition source, the pump, pumps, design the exhaust system gases to bypass the pump into a piping and associated vessels should so that the pump is never subjected freely vented exhaust volume have a minimum design pressure of to a back-pressure greater than 1 • Monitor the pressure of the vacuum 10 bar gauge (145 psig). bar gauge (14.5 psig). Under nor- system and use a positive-closure Eliminate stagnant volumes. A stag- mal operating conditions, the pump valve to shut off the supply of com- nant volume is any closed volume in a should not run continuously with a pressed gas at a preset pressure level vacuum pipe or component that is not back-pressure of more than 0.35 bar Inlet overpressure can also result from subjected to a through flow of gas. Ex- gauge (5.1 psig) incorrect vacuum pump operation, amples are the gear box of a mechani- • Many dry pumps also generate high and special precautions must be taken cal booster pump or the gauge head of exhaust pressures when the exhaust until it has been established that the an instrument. Valved piping and ni- system is blocked or restricted. One pump is operating correctly. trogen-gas inlet pipes can also become well-known dry-pump manufacturer If the direction of rotation of the stagnant when they are isolated. recommends that its dry pumps pump is incorrect and the pump is Stagnant volumes must be taken should not be operated with an ex- operated with the inlet blocked or re- into account when one considers the haust pressure higher than 0.3 bar stricted, the pump will generate high mixture and reaction of process gases gauge (4.4 psig). If there is a risk of pressure in the inlet piping. This could that are not normally present together high exhaust pressures occurring, result in rupture of the pump, the pip- in the process vessel. A stagnant vol- this vendor recommends that the ing and components in the piping. ume is not purged and may be filled system incorporate an exhaust pres- Always use a blanking plate (line with process gases as the pressure in sure switch to shut down the pump blind) loosely secured by screws to the the system rises and falls. In this way, and prevent the recommended pres- pump inlet until it has been estab- gases that pass through the system at sure from being exceeded lished that the direction of rotation for one stage of the process can be retained. • It is recommended that the exhaust the pump is correct. These may then react with gases from system be designed to withstand Operation at high rotational speeds a subsequent phase of the process. an internal pressure of at least 1.3 could result in pump break-up. Do not Thorough evacuation of the process bar gauge (18.9 psig) for oil-sealed operate the pump at rotational speeds chamber between episodes involving pumps and at least 10 bar gauge above the maximum designed speed of the introduction of incompatible gases (14.5 psig) for dry pumps, unless rotation; this is particularly important will lower the risk of an explosion. over-pressure relief is provided. where frequency inverters are used for Special care must be taken when If a vacuum pump exhaust system speed control. considering cross-contamination in contains accessory components that stagnant volumes, especially when the might cause restrictions or blockages General design practices pressure is relatively high (close to at- the protection methods shown in the More details about the design practices mospheric pressure) and the gases are Table (p. 53) should be provided. described below can be found in Ref. 1. potentially explosive. In particular, one Inlet overpressure. The most com- Pressure ratings in a system. Vac- should consider the hazard of buildup mon cause of over-pressure in vacuum- uum systems and piping are designed in filters and separators. Where appro- pump inlet piping is the introduction of to operate with internal pressures priate, use high-integrity, continuous compressed gas (such as purge gases) below atmospheric pressure. In prac- flows of inert purge gas to reduce the when the pump is not operating. If tice, however, it is necessary to design probability of cross-contamination. components in the inlet piping are not the system (pump and piping) for use When pumping flammable gases, it suitable for the pressures that result, with internal pressures above atmo- is possible for stagnant volumes to fill the piping will rupture and process spheric pressure as well. It may be nec- with potentially explosive gases or va- gases will leak from the system. essary to incorporate pressure relief pors that cannot be removed by normal Care must be taken before connect- devices to prevent over-pressurization. purging. When an ignition source may ing compressed gas supplies to the Exhaust systems must always be de- also be present, specific purging of the vacuum system through pressure reg- signed to produce the smallest possible stagnant volume should be considered. ulators, which are designed to provide backpressure to the pump during opera- Sources of potentially explosive gas a low-pressure flow so that the regu- tion. It is important, however, to design or vapor mixtures. When a flammable lated pressure is within the pressure the exhaust system with an adequate gas or vapor is mixed with the correct rating of the vacuum system. The non- pressure rating; it must be suitable for concentration of oxygen or other suit- venting regulators most commonly the pressures that can be generated by able oxidant, it will form a potentially used will cause the pressure within the pump and by the introduction into explosive mixture, which will ignite in the vacuum system to rise to the pres- the system of a compressed gas, and be the presence of an ignition source. sure of the gas supply to the regula- suitable for use with the overpressure- While it is generally apparent if a tor, if operated under conditions where protection measures used. pumped gas or vapor is potentially

50 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 TABLE. OPTIONS FOR PROTECTING VACUUM PUMP EXHAUST SYSTEMS Component Protection method Valve in Interlock the valve so that its piping is always open when the pump is operating exhaust Incorporate a pressure relief bypass Exhaust Incorporate a pressure relief bypass scrubber Incorporate a pressure monitor or sensor and interlock this with the pump motor clusion of air and oxygen from so that the pump is shut down when the exhaust pressure is too high Flame Provide an exhaust pressure measurement or a differential-pressure measurement the process and pump system, arrester and dilution of the pumped gas Oil mist filter Incorporate a pressure-relief device with an inert purge gas (usu- ally nitrogen) that is intro- explosive, there are some conditions • Flammable sealing liquids. Where a duced into the pump inlet or purge where a potentially explosive mixture flammable liquid is used as the seal- connections, if needed. The required is produced due to conditions that ing liquid in a liquid-ring vacuum integrity of the air/oxygen-exclusion were not considered when the process pump, air ingress will create a poten- measures (for example, purging) was designed. One must identify all tially explosive internal mixture and of any alarms or interlocks will possible sources of potentially explo- Avoiding the flammable zone. A depend on the hazardous zone that sive mixtures that could be generated flammable gas or vapor will only cre- would result, were the exclusion and by the process vacuum equipment. Ex- ate a potentially explosive atmosphere dilution systems to fail amples are listed: if it is combined with sufficient air or Precautions typically required to rigor- • Cross-contamination. Where a vac- oxygen (or another oxidant, such as ously exclude air from the process and uum pump is being used for a num- chlorine) and the concentration of the pump system include the following: ber of duties, it is possible that its vapor in the mixture lies between the • Eliminate air leaks. Use a leak detec- use with individual gases or vapors lower flammability limit (LFL) and tor or conduct a pressure-rise test is safe, but if the pump is not purged the upper flammability limit (UFL). • Remove all air from the system before before use with another gas or vapor, To be potentially explosive, it is the start of the process. Before any then cross-contamination could occur also necessary for the concentration flammable gas is admitted into the with unexpected reactions of oxygen to be above the limiting oxi- process, the system should be fully • Cleaning fluids. An application may dant concentration (LOC). There are evacuated and purged with an inert be viewed as benign, but the use of several strategies that can be used to gas (usually nitrogen) to remove all flammable cleaning fluids and the avoid operating with gas mixtures in air from the system. At the end of subsequent drying by evacuation the flammable region. The choice of the process, repeat this procedure through the vacuum pump can cre- strategy will depend on the outcome of before the system is finally vented ate a potentially explosive mixture the hazard analysis for the process and to the atmosphere • Unexpected material. On “house the pumping system. Recommended • Maintain the integrity of shaft-seal vacuum” duties where the vacuum strategies include the following: gas. For dry-vacuum pumps, ensure pump is used to provide a distrib- • Maintain the flammable gas con- that any shaft-seal gas cannot be uted vacuum system, it is possible centration below the LFL. This is supplied with, or contaminated by, to pump flammable gases or vapors accomplished by diluting the flam- air under any circumstances (for that were not considered during sys- mable mixture with an inert gas dry-vacuum pumps). In addition, tem design. These gases or vapors (usually nitrogen) that is introduced ensure that any gas ballast port is may have autoignition temperatures into the pump inlet and/or purge either sealed, or only used to intro- that are lower than the internal connections. Refer to NFPA 69 [2] duce inert gas temperatures of the vacuum pump for recommendations as to what • Follow instructions and maintain • Dissolved vapors. Low autoignition- percentage of the LFL the flamma- proper lubrication. For wet vacuum temperature vapors generally have ble concentration should be main- pumps (rotary piston or rotary vane high vapor pressures. Pumping tained. The required integrity of the pumps), maintain the shaft seals in these vapors at pressures above the dilution system and of any alarms or accordance with the manufacturer’s vapor pressure will generally result interlocks will depend on the nature instructions, and use a pumped, pres- in internal dry-pump stage temper- of the hazards that would result if surized oil-lubrication system with atures below the autoignition point. the dilution system were to fail an alarm that indicates the loss of oil However, it is possible for these va- • Maintain the oxidant concentration pressure. This system may comprise pors to become absorbed in a liquid below the LOC. This mode of opera- an external accessory to provide fil- with a lower vapor pressure, and for tion requires the use of oxygen-con- tered and pressurized lubricating oil, them to be released as the pressure centration monitoring of the pumped with a pressure switch. Ensure that falls below the vapor pressure of the gases to ensure safe operation. To any gas ballast port is either sealed, dissolved vapors. At this lower pres- minimize the risk of flammable gas or only used to introduce inert gas. sure, it is possible for the internal accidentally entering the flammable Provide an adequate purge of inert dry-pump stage temperature to ex- zone, a safety margin below the LOC gas to the oil box, to remove air before ceed the autoignition point should be maintained. NFPA 69 the start of the process • Air leakage. The accidental ingress [2] presents recommendations for • Maintain the drive-shaft seal for of air or oxidant into a vacuum sys- these safety margins. The preferred vacuum booster pumps (such as the tem may change the concentration method of maintaining the oxidant Roots pump). Maintain the primary of a flammable gas or vapor and cre- (usually oxygen) level below the drive shaft seal fully in accordance ate a potentially explosive mixture LOC is to carry out both rigorous ex- with the manufacturer’s instruc-

CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 51 Environmental Manager

tions, and ensure that any purge or condition, and adopt a suitable flame- Flexible hoses. Flexible hoses have breather port connections can only suppression strategy to make the sys- a thicker wall section and shallower be used to introduce inert gas tem safe in the event of a burn being convolutions than bellows. Flexible • Guard against reverse flow. Ensure detected. The suitable strategy depends hoses provide a convenient method that the system operating proce- on the application, but could include for the connection of vacuum system dures and protective equpment pro- the following: components and help to compensate tect the system from any reverse air • Stopping the supply of fuel. Closing for misalignment or small movements flow that might result from a pump a valve located on the inlet of the in rigid vacuum piping. Flexible hoses failure. Ensure that any pumped dry vacuum pump will prevent the can be formed into relatively sharp flammable gases are safely dis- supply of fuel (process gas or vapor) bends that will hold their position. posed of at the final vent from the into the vacuum pump Flexible hoses are intended for in- pump exhaust. Ensure that flam- • Stopping the source of ignition. Stop- stallation in static systems. They are mable gas mixtures cannot occur in ping the pump by turning off power not suitable for repeated flexing, as the exhaust piping. This is done by to the motor will bring the pump to this could cause fatigue failure. When using suitable inert-gas purging of a halt in approximately 10 seconds flexible hoses are used, use the short- the piping before the start of, and • Inerting the area of the burn. The est possible length and avoid unneces- after the end of, the flammable gas rapid addition of inert gas into the sary bends. Do not use flexible hoses process, and by the use of adequate area of the burn (typically, but not on dry pump exhausts. inert-gas purging during operation, always located in the exhaust mani- Anchor points. Piping and piping com- to prevent turbulent back-mixing of fold of the pump) will eliminate the ponents must be anchored correctly. For air down the exhaust flame. Note that it is possible for a example, if bellows are anchored incor- • Maintain the flammable gas concen- flame to reignite if the source of ig- rectly, they will not reduce the vibration tration above the UFL. Where the nition is not removed generated by the pump, and this could flammable gas concentrations are lead to fatigue in the piping. very high, operation above the UFL Piping design Seals. Where there is the possibil- can be used. Procedures for doing this This section discusses design prac- ity of positive pressure occurring in are given in NFPA 69 [2]. To maintain tices for piping components used with any part of the vacuum system (even the oxygen at a safe level, rigorous mechanical vacuum pumps. under failure conditions), one must use exclusion of air and oxygen from the Bellows. Bellows are short, thin- trapped O-ring type seals, which are process and pump system is required. walled components with deep convo- capable of withstanding the expected This can be accomplished by dilution lutions. They are used to reduce the vacuum and positive pressures. of the pumped gas with an inert gas transfer of vibration from a pump to a (usually nitrogen) or by addition of vacuum system. They are available in Physical over-pressure enrichment flammable gas (NFPA metal, rubber or plastic construction. protection 69 discusses the use of methane for Always install bellows in a straight Over-pressure can be caused by a re- this), introduced into the pump inlet line with both ends rigidly con- striction or blockage in the vacuum and/or purge connections strained. When installed correctly, the system or in one of its components. Use of flame-arrester protection bellows can withstand a small positive The over-pressure may also occur as a systems. When dry vacuum pumps internal pressure (refer to the Instruc- result of compressed-gas flow from the are used for pumping gases or vapors tion Manual supplied with the bellows pump or from external compressed gas that could enter the flammable zone for details). Note: Do not use bellows supplies (such as those for a dilution under abnormal conditions, exhaust on dry vacuum-pumps’ exhausts: use system). There are two main methods flame arresters should be installed to braided flexible bellows (see below). of over-pressure protection, as follows: quench any resulting flame front in Braided flexible bellows. Braided flex- Pressure relief. Rupture disks or the event of an ignition. Flame arrest- ible bellows are bellows with an outer pressure-relief valves may be used ers should be closely coupled to the ex- protective layer of woven stainless- to relieve an overpressure situation. haust connections. steel braid. They are suitable for use These devices must be provided with Where there is the possibility of con- as exhaust connections on dry pumps discharge piping to convey the relief tinuous burning within a dry vacuum and other applications where there is device discharge fluid to a safe location pump, special precautions should be significant gas pulsation or the possi- (where plant personnel are not usually taken. Such conditions could occur due bility of high gas pressures. located), and the vent line should have to a continuous ignition source result- Braided flexible bellows are intended no restrictions. If the process produces ing from the accidental pumping of a for installation in static systems. They solid byproducts, the pressure-relief gas or vapor with an auto-ignition tem- are not suitable for repeated flexing, as devices must be inspected on a regu- perature lower than the internal pump this could cause fatigue failure. When larly scheduled basis to ensure that temperatures. In this case, one must a braided flexible bellows is installed, they are not blocked or restricted. use a PT100 or equivalent tempera- one must comply with the minimum Over-pressure alarm or trip. This ture-sensing device on the pump side bend radius given in the manufactur- method of protection is used by several of each flame arrester to detect a burn ers’s instruction manual. vacuum-pump system manufacturers.

52 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 This type of protection can be used for The control system should be de- Acknowledgements any vacuum-pump system, but it is signed so that both the pump and any The author wishes to thank J.L. Ryans of East- man Chemical Co. (Kingsport, Tenn.) for his re- particularly suitable for systems that gas inlets (which are capable of pres- view of the draft of this article and for his help- produce solid byproducts. surizing the system above its maxi- ful comments and recommendations. I should also like to acknowledge the assistance of the Since the use of an alarm or trip mum operating pressure) are shut following people, who provided technical infor- system forms part of a primary safety down when the trip point is reached. mation used during the development of this ar- ticle: Peter N. Lodal (Eastman Chemical Co.), system, it must incorporate a design Purge systems. The correct use of John Campbell (SIHI Pumps Americas), Mark Nichols (Edwards Ltd.), and Eric Johnson (Gra- of high integrity. One should not rely a purge (usually nitrogen) can ensure ham Manufacturing Co.). on a simple pressure switch or sensor that corrosive products are removed, installed in a flow line, as the conden- preventing them from damaging the Author sation of solid particles or corrosion of vacuum pump, and also from plugging Stanley S. Grossel is president of Process Safety the sensor can cause the device to fail or damaging protective systems such and Design, Inc. (4 Marble Court, Unit 9, Clifton, N.J. 07013-2212; Phone: 973-779-3668; Email: without indication of the failure. as flame arresters. In addition, the [email protected]). He provides consulting ser- It is also recommended that a sen- removal of process gases ensures that vices related to process safety and loss prevention, storage and handling of bulk solids and powders, sor be used that incorporates a nitro- undesired and potentially dangerous air pollution control, and process design of batch gen purge flow to the sensor. A purge chemical reactions do not occur be- plants. Prior to his 1993 retirement, Grossel spent 25 years in the Engineering Dept. of Hoffman-La- flow keeps the sensor relatively free tween process gases and vapors used Roche, in a variety of roles. He was honored as the from blockage, and such a sensor is de- in different process cycles. ■ only Senior Engineering Fellow ever to be desig- nated by Hoffman-LaRoche. Grossel is a fellow of signed so that, if the sensor is blocked, Edited by Suzanne Shelley AIChE, and holds AIChE’s Norton Walton/Rus- sell Miller Award for outstanding contributions to the nitrogen supply pressure is high loss prevention. He has lectured and been pub- enough to operate the pressure alarm lished widely, and has authored major standards References and guidelines. Grossel is also a contributor on and trip. The normal settings for such 1. Edwards Ltd., Safety Manual-Vacuum Pump process safety to the 7th Ed. of “Perry's Chemical devices are usually no higher than 0.3 and Vacuum (corporate manual). Engineers’ Handbook.” He holds a B.S.Ch.E. from bar gauge (4.35 psig) and no greater 2. NFPA 69, Standard on Explosion Prevention City College of New York and an M.S.Ch.E. from Systems, National Fire Protection Associa- Drexel Inst. of Technology, and has completed than 0.4 bar gauge (5.80 psig). tion, Quincy, Mass., 2008. courses toward a doctoral degree.

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510 Sep ‘06 Aug ‘06 Sep ‘05 Prelim. Final Final CE Index 513.1 510.0 467.2 500 Equipment 606.5 602.3 541.2 Heat Exchanges and Tanks 565.1 560.9 509.2

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CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 53 The entire shale drilling community will come together in one place to take part in the event focused on environmental, health, safety, and regulatory considerations faced by the industry.

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ccording to my version of the story, Unfortunately, his friends Robert Kohler said, “We don’t need weren’t working the gates visas to enter Hungary.” Accord- on that particular day. Our A Mike Resetarits is the technical director at Fraction- ing to Robert’s version, he said, taxi driver slowed but did “It’s easy to get visas to enter Hungary.” not stop. Two very young ation Research, Inc. (FRI; Stillwater, Okla.; www. fri.org), a distillation research consortium. Each Either way, he was wrong. Either way, Hungarian soldiers were month, Mike shares his irst-hand experience with he got us to Budapest. very unimpressed by the CE readers Robert Kohler and I visited the explanation that our driver OMV plant in Schwechat, Austria, shouted as we drove past them. They they travel abroad, their American on a Friday morning. At Robert’s urg- un-slung their weapons. They looked passports and American dollars will ing, we decided to go to Budapest at each other, wondering whether to pave their way to and from anywhere for the weekend, without visas. We shoot or not. Robert and I looked at and will shield them from all troubles. took a Vienna-to-Budapest train that each other, wondering whether to Whether at the border to Hungary, or stopped at the Hungarian border. The slouch or not. They did not. We did. in a market square in Mongolia, the immigration agent was unimpressed Within two minutes we were back U.S. State Department does not re- by our visa-less American passports. at the train station and on the very ally know you. You’re on your own. Be He ordered us off the train — and our same train that we were thrown off careful. ■ luggage too. of, and headed toward Budapest. Mike Resetarits We found ourselves in a very small Some Americans feel that, when [email protected] border station that some might call a cottage. A tall black-haired taxi driver with a brown leather beret approached us hurriedly and requested $20 each for emergency visa service. We had no other options that we knew about. Robert and I agreed to his price. The taxi driver ran to his cab. Robert and I power-walked behind him, lugging our luggage behind us. Before the car doors were closed, the taxi was speed- ing through a recently harvested corn field. After a 15-min ride, most of my teeth were loose. When the cab exited the cornfield, we were faced by a high- way border station with buildings that looked governmental. The taxi driver stated, in reasonably good English, “Leave your bags in the cab. We. Must. Hurry.” Inside the building, we encountered a long line. Our taxi driver took us to the front of the line, by shouting something in Hungarian that did not completely satisfy everybody that we were cutting in front of. Nevertheless, we left the building with photographs and stamps in our passports. We jumped back into the taxi and sped toward an automobile border crossing that had three closed lanes and three open lanes. Each open lane had 20 cars in each. Our driver took us to one of the closed lanes. Circle 4 on p. 60 or go to adlinks.che.com/40272-04 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 55 PRODUCT SHOWCASE Precise Density Measurement For Caustics and Acids

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CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 59 New Product Information October 2012 JustFAXit! or go to www.che.com/adlinks Fill out the form and circle or write in the number(s) go on the web and ill out the below, cut it out, and fax it to 800-571-7730. online reader service card. ✁ name title

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60 ChemiCal engineering www.Che.Com oCtober 2012 Advertisers’ Index

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MultiTherm LLC 8 Send Advertisements and Box replies to: Diane Hammes 1-800-225-7440 adlinks.che.com/40272-15 Chemical Engineering, 11000 Richmond Ave, Houston, TX 77042 E-mail: [email protected] Tel: 713-343-1885 * International Edition CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 61 People

OCTOBER WHO’S WHO

Thill Peeters Rosenberger Pace Lind SNC-Lavalin (Montreal, Quebec), a control products, names Bill Bendel Conrad Winters becomes director of global engineering and construction technical sales manager and drug product development for group that specializes in infrastruc- Terri Simmons global customer Hovione (Loures, Portugal), a ture and operations and maintenance service manager. global producer of active pharmaceu- services, names Robert Card tical ingredients and drug president and CEO. Dow Corning Electronics Solu- product intermediates. tions (Midland, Mich.) promotes Tony Thill becomes president of Eric Peeters to vice president. Abresist Kalenborn Corp. (Urbana, CST International (Lexana, Kan.), Ind.), a manufacturer of impact- and a global manufacturer of factory- The Hallstar Co. (Chicago, Ill.), a wear-resistant linings, appoints coated metal storage tanks, alumi- producer of specialty ingredients for Jennifer Lind as a territory manager num domes and related products. use in industrial and personal care for Mississippi, Alabama, western applications, promotes David Rosen- Tennessee, eastern Arkansas and the Blachoh Fluid Control (Riverside, berger to vice president of sales and panhandle of Florida. ■ Calif.), a maker of industrial fluid Louis Pace to chief operating officer. Suzanne Shelley

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Reverse PAGE 34 Osmosis Heat Transfer More and more, business in the Chemical Process Industries (CPI) is not Fluids Hydrocarbon Properties local, it’s global. To keep up with this rapidly evolving marketplace, you need a magazine that covers it all, not just one country or region, not just Focus on Filtration Facts at Your r Lessons-Learned Fingertips: Systems Valves one vertical market, but the whole CPI. Preventing Caking With editorial offices in Europe, Asia, and North America, CHEMICAL ENGINEERING is well-positioned to keep abreast of all the latest innovations in the equipment, technology, materials, and services used by process plants worldwide. No other publication even comes close. The #1 choice of worldwide To subscribe, please call 1-847-564-9290 CPI organizations or visit [email protected] www.che.com

62 CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 Economic Indicators BUSINESS NEWS PLANT WATCH underground, more than 1-million m.t./yr of Lummus propane-dehydrogenation CO2 produced in bitumen processing. The technology selected for unit in China Solvay increases fluorinated-derivatives Alberta government will invest $745 million August 28, 2012 — CB&I (The Woodlands, production capacity in France in Quest from a $2-billion fund to support Tex.; www.cbi.com) has been awarded a September 6, 2012 — Solvay S.A. (Brussels, CCS, while the Government of Canada will contract by the Hebei Haiwei Group for the Belgium; www.solvay.com) is investing invest $120 million through its Clean Energy license and basic engineering design of a over €10 million to double the capacity Fund. Quest is said to be the world’s first grassroots propane dehydrogenation unit of the fluorinated aliphatic-derivatives commercial-scale CCS project to tackle to be located in Jingxian, Hebei Province, production line at its plant in Salindres, carbon emissions in the oil sands. Shell has China. The unit will use the Catofin propane France. The project’s first stage is cur- received the necessary federal and provin- dehydrogenation process from Lummus rently underway. The Group decided to cial regulatory approvals for Quest. Technology that employs Süd-Chemie’s double production capacity for triflic acid latest Catofin catalyst to produce 500,000 and triflic anhydride, as well as for lithium Lanxess to build the world’s largest m.t./yr of propylene. The unit is expected to bis(trifluoromethanesulfonyl)imide to meet EPDM plant in China start up in 2015. the rapidly expanding requirements of September 4, 2012 — Lanxess AG (Le- electronic applications and the battery and verkusen, Germany; www.lanxess.com) Foster Wheeler awarded contract for pharmaceuticals markets. is building what is said to be the world’s gas-to-chemicals complex in Brazil largest plant for ethylene propylene diene August 23, 2012 — Foster Wheeler AG (Zug, BASF to build production plant for monomer (EPDM) synthetic rubber in Chi- Switzerland; www.fwc.com) says that a sub- specialty zeolites in Ludwigshafen na. The company is investing €235 million in sidiary of its Global Engineering and Con- September 6, 2012 — BASF SE (Ludwig- the plant in Changzhou, Jiangsu Province. struction Group has been awarded a con- shafen, Germany; www.basf.com) is invest- The plant will have a capacity of 160,000 tract by Petróleo Brasileiro S.A. (Petrobras) ing in the construction of a production plant m.t./yr and is expected to start up in 2015. for a gas-to-chemicals complex in Linhares, for specialty zeolites at its Ludwigshafen, All necessary permits have been obtained Espirito Santo State, Brazil. Foster Wheeler will Germany site. The plant is expected to start from the local authorities. provide basic and front-end engineering up operations in the 1st Q of 2014. BASF cur- design, as well as additional assistance. The rently produces specialty zeolites at its oper- Technology from Veolia Water Solutions is design phase is scheduled for completion ating site in Seneca, S.C., where production selected for potash and salt recovery at the end of 2013.The complex is expected capacity is also being expanded. August 30, 2012 — Veolia Water Solutions & to produce more than 1-million m.t./yr of Technologies (Saint Maurice, France; www. ammonia and urea fertilizers, methanol, NatureWorks broadens Ingeo product veoliawaterst.com) has been awarded the acetic acid, plus formic acid and melamine. portfolio with Sulzer equipment supply of a large-scale evaporation and September 6, 2012 — Sulzer Chemtech crystallization plant by Iberpotash, S.A., a MERGERS AND ACQUISITIONS Ltd. (Winterthur, Switzerland; www. business unit of ICL Fertilizers. Iberpotash pro- sulzerchemtech.com) is supplying pro- duces potash fertilizers from sylvinite mining BP agrees to sell Carson refinery and prietary production equipment to the from deposits located near Suria, Spain. The Arco Retail Network to Tesoro NatureWorks LLC (Minnetonka, Minn.; www. plant, to be completed in 2014, will recover August 13, 2012 — BP (London, U.K.; www. natureworksllc.com) Blair, Nebr., facility to and purify high-quality sodium chloride and bp.com) has reached an agreement to enable NatureWorks to increase production potassium chloride from byproduct salts sell its Carson, Calif. petroleum refinery and of Ingeo biopolymer and produce high-per- resulting from the production of fertilizer. Uti- related logistics and marketing assets in formance resins and lactides. Ingeo produc- lizing technology from Veolia, Iberpotash will the region to Tesoro Corp. for $2.5 billion tion capacity at Blair will rise from 140,000 expand production capabilities to include in cash (including the estimated value to 150,000 metric tons per year (m.t./yr). 750,000 tons/yr of chemical and food-grade of hydrocarbon inventories and subject Commissioning of the new equipment is salts, as well as recover up to 50,000 tons/yr to post-closing adjustments) as part of a expected in the 1st Q of 2013 with capac- of white potash from the process. previously announced plan to reshape BP’s ity increases and new products becoming U.S. fuels business. Subject to regulatory available in the 2nd Q. Linde to build Vietnam’s largest and other approvals, Tesoro will acquire the air separation unit 266,000-bbl/d refinery near Los Angeles as Shell to construct the world’s first oil-sands August 29, 2012 — The Linde Group (Mu- well as the associated logistics network of carbon capture and storage project nich, Germany; www.linde.com) has been pipelines and storage terminals and the September 5, 2012 — Shell (The Hague, awarded a long-term contract to supply Arco-branded retail marketing network in the Netherlands; www.shell.com) plans Vietnamese steel-company Posco SS-Vina Southern California, Arizona and Nevada. to go ahead with the first carbon capture (PSSV) with industrial gases. The deal will see The sale also includes BP’s interests in and storage (CCS) project for an oil sands Linde construct the country’s largest air sep- associated cogeneration and coke operation in Canada. The so-called Quest aration unit (ASU) at the Phu My industrial calcining operations. The closing is expected project will be built on behalf of the Atha- park in Ba Ria. The Group will be investing a to happen before mid-2013. This is part of the basca Oil Sands Project joint venture owners total of around €40 million in the project. The previously announced program to divest $38 (Shell, Chevron and Marathon Oil). From ASU will be able to produce 35,000 Nm3/h of billion of assets by the end of 2013. ■ late 2015, Quest will capture and store, deep gases, and is set to go onstream in 2014. Dorothy Lozowski

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October 2012; VOL. 119; NO. 10 Chemical Engineering copyright @ 2012 (ISSN 0009-2460) is published monthly, with an additional issue in October, by Access Intelligence, LLC, 4 Choke Cherry Road, 2nd Floor, Rockville, MD, 20850. Chemical Engineering Executive, Editorial, Advertising and Publication Offices: 88 Pine Street, 5th Floor, New York, NY 10005; Phone: 212-621-4674, Fax: 212-621-4694. Subscription rates: $149.97 U.S. and U.S. possessions, $166.97 Canada, and $269 International. $20.00 Back issue & Single copy sales. Periodicals postage paid at Rockville, MD and additional mailing offices. Postmaster: Send address changes to Chemical Engineering, Fulfillment Manager, P.O. Box 3588, Northbrook, IL 60065-3588. Phone: 847-564-9290, Fax: 847-564-9453, email: [email protected]. Change of address, two to eight week notice requested. For information regarding article reprints, please contact Wright’s Media, 1-877-652-5295, [email protected]. Contents may not be reproduced in any form without written permission. Canada Post 40612608. Return undeliverable Canadian Addresses to: PitneyBowes, P.O. BOX 25542, LONDON, ON N6C 6B2

FOR MORE ECONOMIC INDICATORS, SEE NEXT PAGE CHEMICAL ENGINEERING WWW.CHE.COM OCTOBER 2012 63 Economic Indicators 2010 2011 2012

DOWNLOAD THE CEPCI TWO WEEKS SOONER AT WWW.CHE.COM/PCI

CHEMICAL ENGINEERING PLANT COST INDEX (CEPCI) 650 (1957-59 = 100) July '12 June '12 July '11 Annual Prelim. Final Final Index: CE Index 582.2 585.6 593.2 600 2004 = 444.2 Equipment 708.5 713.9 724.1 Heat exchangers & tanks 652.0 661.4 681.8 2005 = 468.2 550 Process machinery 664.7 666.5 675.8 2006 = 499.6 Pipe, valves & fittings 911.3 917.7 915.3 2007 = 525.4 500 Process instruments 424.2 425.1 446.9 2008 = 575.4 Pumps & compressors 928.9 927.0 909.5 2009 = 521.9 Electrical equipment 509.7 513.7 512.5 450 2010 = 550.8 Structural supports & misc 757.8 759.9 764.7 2011 = 585.7 Construction labor 323.9 322.6 326.9 400 Buildings 525.6 527.1 520.5 JFMAMJJASOND Engineering & supervision 328.0 327.9 332.1

CURRENT BUSINESS INDICATORS LATEST PREVIOUS YEAR AGO

CPI output index (2007 = 100) Aug. '12 = 87.4 Jul. '12 = 87.8 Jun. '12 = 87.5 Aug. '11 = 87.6 CPI value of output, $ billions Jul. '12 = 2,097.5 Jun. '12 = 2,059.0 May. '12 = 2,116.1 Jul. '11 = 2,113.3 CPI operating rate, % Aug. '12 = 75.4 Jul. '12 = 75.7 Jun. '12 = 75.5 Aug. '11 = 75.6 Producer prices, industrial chemicals (1982 = 100) Aug. '12 = 292.9 Jul. '12 = 295.4 Jun. '12 = 312.7 Aug. '11 = 337.0 Industrial Production in Manufacturing (2007=100) Aug. '12 = 94.1 Jul. '12 = 94.8 Jun. '12 = 94.5 Aug. '11 = 90.7 Hourly earnings index, chemical & allied products (1992 = 100) Aug. '12 = 156.9 Jul. '12 = 158.9 Jun. '12 = 157.2 Aug. '11 = 156.6 Productivity index, chemicals & allied products (1992 = 100) Aug. '12 = 102.5 Jul. '12 = 103.2 Jun. '12 = 103.7 Aug. '11 = 107.2

CPI OUTPUT INDEX (2007 = 100) CPI OUTPUT VALUE ($ BILLIONS) CPI OPERATING RATE (%)

120 2500 85

110 2200 80

100 1900 75

90 1600 70

80 1300 65

70 1000 60 JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND

Current Business Indicators provided by IHS Global Insight, Inc., Lexington, Mass.

CURRENT TRENDS apital equipment prices, as reflected in the CE Plant Cost growth in June. The data indicate that production of organic CIndex (CEPCI; top), dropped 1.9% from June to July (the and inorganic basic chemicals was up slightly, as was that of most recent data). Meanwhile, the Current Business Indicators synthetic rubber, but those gains were offset by declines in plas- from IHS Global Insight (middle), including the operating rate, tic resins and artificial fibers, according to the ACC report. dropped slightly from July to August. Meanwhile, wholesale sales of chemicals rose by 0.5% in July, According to the American Chemistry Council’s (ACC; Wash- to $10.2 billion. This follows a 1.3% gain in June, ACC noted. ington, D.C.; www.americanchemistry.com) latest weekly eco- Chemical inventories were also up. Compared to a year ago, nomic report at CE press time, production by the U.S. chemi- chemical sales at the wholesale level were up 4.8%, outpacing cal industry fell by 0.3% in August. The drop left production at the 3.0% rise in inventories, ACC said. 85.7% of its average level from 2007, ACC noted. The lower For more on capital cost trends and methodology, visit: production in August follows a similar decline in July and flat www.che.com/pci ■

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