DOCSLIB.ORG

Wet Scrubbers for Dry Dust? Absolutely

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Wet Scrubbers for Dry Dust? Absolutely February 2014 APC www.APCmag.net As appeared in Copyright CSC Publishing Wet Scrubbers for Dry Dust? Absolutely. Ron Hatton Sly Inc. quired design modifications needed on the scrub- Wet scrubbing in industrial processes sometimes ber, as there are with dry dust collectors. A dry col- can be an overlooked method for air pollution con- lector requires special grounding for the tubesheet trol. Whether the reasoning is reluctance to change and filter bags, along with the use of explosion from well-known, typical dry collection tech- vents or chemical suppression. These safety de- niques, concerns over handling dirty water, or sim- vices require periodic inspections and preventative ply being unaware that the technology is available maintenance to ensure that they function properly for an application, wet scrubbing is not typically at if an accident occurs. the forefront of engineers’ or process personnel’s Due to several tragic and fatal events in recent years, list of equipment for controlling plant emissions. the National Fire Protection Association (NFPA) and The purpose of this article is to highlight the bene- Occupational Safety and Health Administration fits and potential advantages of using a wet scrub- (OSHA) have broadened the application and tight- ber system. ened the enforcement of safety measures with regard to both plant housekeeping and equipment design. The increased safety requirements have been imple- mented to protect workers, plants, and equipment. et scrubbers can be used for controlling Although not all explosions occur inside dust con- exhaust from process equipment or as trol equipment, as happened in a housekeeping-re- nuisance collectors designed to address W lated explosion that occurred recently at a sugar housekeeping issues. There are many successful in- refinery, dust collectors provide ideal environments stallations of wet scrubbers downstream of furnaces, for deflagration to occur. Examination of explosions dryers, mixers, bucket elevators, bagging stations, shows that there are five elements necessary for an and other emission points. The versatile technology explosion to take place: fuel (combustible dust), en- is not only an alternative to more traditional pollu- closure, dispersion (dust cloud), oxygen, and an ig- tion control equipment, in some cases, wet scrubbers nition source. All five of these elements must be are the best option. present to have a deflagration. Baghouses and car- tridge filters can create an environment that fulfills Combustible/Hazardous Dusts four of the requirements. The fifth one — the igni- For instance, if you have an application where the tion source — could be provided by the process particulate being collected is combustible, a wet (spark), careless workers (cigarette), or mainte- scrubber can be an ideal choice. Using water to nance/construction near the collector (welding or scrub particulate from an airstream eliminates the grinding spark). Dust carrying a static charge also explosion potential of the dust. There are no re- can arc inside the dirty air chamber, causing igni- Copyright CSC Publishing tion. All of these situations are real and do happen. expensive. Decreasing inlet temperatures can be Baghouses and cartridge filters can be successfully accomplished by dilution (adding ambient air), ra- protected by equipping them with explosion vents diant cooling, or water sprays. All of these meth- and suppression systems. The process and plant ods dramatically add to baghouse system costs, are protected by isolating the system ductwork and, in the case of using water to reduce the tem- with fast-action dampers or suppression to prevent perature, expensive controls are required to make the flames from moving down the inlet ductwork sure an excess amount of moisture does not find its and back into the plant and process. Statistics show way to the collector. that the majority of damage to a plant is caused by An alternative approach would be a wet scrubber. secondary explosions. All of these protection de- Because adding water into the system does not af- vices are expensive and require ongoing mainte- fect scrubber operation, quench systems can be em- nance and inspections that add costs to plant ployed prior to the inlet to the scrubber. A scrubber operating budgets. that includes a pre-quench section is capable of Wet scrubbers can be a viable alternative to using a handling temperatures in excess of 2,000°F. While dry collector in these types of applications. Using these quench systems add to the cost of equipment, water as the collection media, a scrubber inherently the reduction in air volume reduces scrubber size, eliminates the dust cloud and explosion potential by and there is no concern about moisture carryover immediately wetting the dust and saturating the into the unit. airstream. There is no threat from an external (or in- Examples where scrubber technology has been suc- ternal) ignition source — provided that the convey- cessfully implemented would be furnaces, kilns, and ing media is not a combustible gas. Therefore, a wet incinerators. scrubber eliminates the requirement for explosion and isolation protection, saving capital and long- term operating costs. Moisture in the Gas Stream If your process has a moisture content in the gas The previously cited example of an industrial explo- stream that would foul or plug a dry dust collector, a sion in a sugar refinery would be an excellent exam- wet scrubber could handle these difficult conditions ple of when a wet scrubber should be considered. without any issues. Since the scrubber uses water to Other such applications where combustion concerns saturate the gas stream for particulate removal, the are present include handling metal fines, chemicals, moist process gas is easily introduced into the scrub- and many organic materials. ber. These same gas stream conditions in a dry dust collector can result in severe caking on filter bags, High-Temperature Gases plugging of discharge equipment, high differential High-temperature applications also can be very fit- pressures, and frequent filter changes and mainte- ting for wet scrubbers. With a dry dust collector, you nance attention. have special high-temperature construction require- Dryers, kilns, and other process equipment are de- ments that need to be addressed during the design, as signed to drive off moisture from the product. The well as expensive high-temp filter bags that are very result is that the air or gas used in the process picks costly to replace. With a wet scrubber, the standard up this moisture and carries it to the dust collector. designs can handle the high temperatures of the Baghouses and cartridge filters are popular collec- process without any special design considerations or tion devices for these applications but bring with expensive replacement parts. them potential problems with moisture. Even wet In many of today’s processes, extremely high tem- compressed air, the method for pulse cleaning peratures are required. Baghouses and cartridge bags and cartridges, can cause operating problems filters — generally designed for lower tempera- by adding unwanted moisture, causing operating tures — can be designed for temperatures up to and maintenance issues with pulse valves, sole- 550°F using filter media such as fiberglass or PTFE. noid valves, and filter media. Moisture issues are Ceramic or stainless steel media can push operat- difficult to overcome with special media, which ing temperature over 700°F, but they are extremely can be expensive and may only offer temporary Copyright CSC Publishing fixes. Many installations will require insulating the For example, a process that produces solid particu- collector and, at times, the addition of auxiliary late and contains HCl in the airstream can easily be heat to control condensation during startup and filtered within a scrubber system. The water will shutdown of the process. collect the solid particulate through inertial im- paction and interception. By adding a caustic solu- Wet scrubbers are not affected by moist or wet air tion (such as sodium hydroxide) to the water and require no compressed air, insulation, or auxil- stream, the HCl will be scrubbed from the gas iary heat. No filter media means no expensive bag stream and converted to NaCl (sodium chloride) in change-outs and no unscheduled down time. the recirculated water. With the particulate and the harmful gas removed from the airstream, the Particulate and Gaseous Contaminants scrubber exhaust now can vent to atmosphere. And Wet scrubbers are a logical choice for applications since the scrubber solution is nonhazardous, deal- that have both particulate and gaseous emissions to ing with the wastewater can be easily managed. be removed from the airstream before it vents to at- mosphere. With a dry dust collector, gaseous emis- Financial Advantages of Wet Scrubbers sions cannot be addressed as it will only collect the Besides addressing aggressive process-related en- solid particulate. There would need to be a sec- vironments, wet scrubbers can provide financial ondary piece of equipment, such as a scrubber or relief as well. In many cases, a wet scrubber has a RTO, installed to remove the gases. Wet scrubbers lower initial capital cost, better energy savings, can collect the solids, as well as scrub the gaseous lower maintenance costs, and no replacement filter components from the airstream all in one piece of equipment. bags/media to account for. Wet scrubbers are fairly simple in their design and do not have any in- ternal moving parts. Impingement Plate Scrubber Airflow is drawn into scrubber and passes through plate Impingement plate scrubbers collect particulate and water, which traps contaminants. These designs are absorb vapors and gases. High collection efficiencies (99+ suitable for applications that require collection of both percent) can be achieved with low water consumption particulate and gaseous contaminants. and minimum pressure drop. Copyright CSC Publishing Chart 1 shows the comparison of a typical 10,000 cfm, emission requirements. Impingement plate (or tray) low energy scrubber and dust collector.
Load more

Recommended publications
  • Comparison of Chemical Wet Scrubbers and Biofiltration For
    Journal of Chemical Technology and Biotechnology J Chem Technol Biotechnol 80:1170–1179 (2005) DOI: 10.1002/jctb.1308 Comparison of chemical wet scrubbers and biofiltration for control of volatile organic compounds using GC/MS techniques and kinetic analysis James R Kastner∗ and Keshav C Das Department of Biological and Agricultural Engineering, The University of Georgia, Athens, GA, 30602, USA Abstract: Increasing public concerns and EPA air regulations in non-attainment zones necessitate the remediation of volatile organic compounds (VOCs) generated in the poultry-rendering industry. Wet scrubbers using chlorine dioxide (ClO2) have low overall removal efficiencies due to lack of reactivity with aldehydes. Contrary to wet scrubbers, a biofilter system successfully treated the aldehyde fraction, based on GC/MS analysis of inlet and outlet streams. Total VOC removal efficiencies ranged from 40 to 100% for the biofilter, kinetic analysis indicated that the overall removal capacity approached 25 g m−3 h−1, and aldehyde removal efficiency was significantly higher compared with chemical wet scrubbers. Process temperatures monitored in critical unit operations upstream from the biofilter varied significantly during operation, rising as much as 30 ◦C within a few minutes. However, the outlet air temperature of a high intensity scrubber remained relatively constant at 40 ◦C, although the inlet air temperature fluctuated from 50 to 65 ◦C during monitoring. These data suggest a hybrid process combining a wet scrubber and biofilter in series could be used to improve overall VOC removal efficiencies and process stability. 2005 Society of Chemical Industry Keywords: odor; volatile organic compounds (VOC); aldehydes; wet scrubber; biofilter; gas chromatography; mass spectrometry INTRODUCTION and odor complaints have resulted in the need for low Rendering operations convert organic wastes (feathers, cost, effective treatment options.
    [Show full text]
  • Application Note Wet Flue Gas Desulfurization Scrubbers Power: Environmental
    Application Note Wet Flue Gas Desulfurization Scrubbers Power: Environmental Coal fi red power plant emissions are a global concern. collects in the bottom of the absorber. A paste-like calcium The burning of coal produces sulfur dioxide (SO2). When sulfi te (CaSO3) sludge forms in the liquid. CaCO3 can be released into the atmosphere SO2 combines with water very diffi cult to remove if it settles out at the bottom of the to form sulfuric acid (H2SO4). Coal fi red power plants will absorber. More recent scrubber designs will blow outside use a fl ue gas desulfurization (FGD) scrubber to remove air through liquid to convert the sulfi te to sulfate in the the SO2 before release up the stack. The scrubbing following reaction. process is pH dependent. In this paper we will explore some of the challenges in this type of pH measurement. CaSO3 + H2O + 1/2O2 ► CaSO4 + H2O The FGD scrubber uses chemical reagents sprayed into The addition of air is referred to as forced oxidation. The the fl ue gas to react with the SO2. Many different reagents resulting calcium sulfate (CaCO4) crystallizes in the liquid have been used over the years. Examples include and is easily removed through fi ltration. An added benefi t ammonia, caustic, lime, limestone, and sodium carbonate. from the process is that CaCO4 (known as gypsum) can Due to cost, the most common reagents are Lime (CaO) be sold as additive for wallboard and cement production. and Limestone (CaCO3). Since both chemicals are very similar we will limit the scope of this paper to them.
    [Show full text]
  • Wet Gas Scrubbing
    CHAPTER 41 WET GAS SCRUBBING Wet scrubbers use a liquid to remove solid, liquid, or gaseous contaminants from a gas stream. The scrubbing liquid performs this separation by dissolving, trap- ping, or chemically reacting with the contaminant. Scrubbers are used extensively to control air polluting emissions. So many dif- ferent scrubber configurations have been used that there is some confusion as to whether they all belong in the same category. In some references, for example, the definition of a scrubber may be restricted to certain design criteria, such as whether the units are open or packed. In this text, any device fitting the definition of the first sentence is a wet scrubber. Scrubber systems can be designed to remove entrained paniculate materials such as dust, fly ash, or metal oxides, or to remove gases, such as oxides of sulfur (SOx), from a flue gas stream to meet air emission standards. PARTICLE COLLECTION CONCEPTS In scrubbing paniculate matter from gases, the principal concern is usually removal of particles smaller than than 10 /on. Larger particles are relatively easy to separate. The successful design and operation of wet scrubbers depends on knowing the size, composition, and derivation of the particles to be collected. Figure 41.1 shows estimated size for some common pollutants. Just as fine particles in water (colloids) carry a charge of static electricity, so do colloidal par- ticles in the fumes and dust, defined as aerosols. If these particles carry no charge, they may be deliberately charged to assist removal by special separators called electrostatic precipitators. Among the particulates (term for the suspended solid materials) collected by wet scrubbers are dispersion aerosols from processes such as grinding, solid and liquid atomization, and transport of suspended powders by air currents or vibra- tion.
    [Show full text]
  • 2.2 Sewage Sludge Incineration
    2.2 Sewage Sludge Incineration There are approximately 170 sewage sludge incineration (SSI) plants in operation in the United States. Three main types of incinerators are used: multiple hearth, fluidized bed, and electric infrared. Some sludge is co-fired with municipal solid waste in combustors based on refuse combustion technology (see Section 2.1). Refuse co-fired with sludge in combustors based on sludge incinerating technology is limited to multiple hearth incinerators only. Over 80 percent of the identified operating sludge incinerators are of the multiple hearth design. About 15 percent are fluidized bed combustors and 3 percent are electric. The remaining combustors co-fire refuse with sludge. Most sludge incinerators are located in the Eastern United States, though there are a significant number on the West Coast. New York has the largest number of facilities with 33. Pennsylvania and Michigan have the next-largest numbers of facilities with 21 and 19 sites, respectively. Sewage sludge incinerator emissions are currently regulated under 40 CFR Part 60, Subpart O and 40 CFR Part 61, Subparts C and E. Subpart O in Part 60 establishes a New Source Performance Standard for particulate matter. Subparts C and E of Part 61--National Emission Standards for Hazardous Air Pollutants (NESHAP)--establish emission limits for beryllium and mercury, respectively. In 1989, technical standards for the use and disposal of sewage sludge were proposed as 40 CFR Part 503, under authority of Section 405 of the Clean Water Act. Subpart G of this proposed Part 503 proposes to establish national emission limits for arsenic, beryllium, cadmium, chromium, lead, mercury, nickel, and total hydrocarbons from sewage sludge incinerators.
    [Show full text]
  • Odor Control System
    ODOR CONTROL SYSTEM What is an Odor? An odor is defined as a sensation resulting from the reception of a stimulus by the olfactory sensory system. Controlling odors is an important consideration for protecting the environment and our community amenity. Odors can be generated from a vast range of sources including sewage treatment processes and industrial effluents. Odor Control Technologies Typical odor emission control applications are the removal of odor from sewage treatment plants & sewage wet waste. Odor related complaints from communities surrounding WWTPs have been increasing for many WWTPs. Here, several emission sources need odor control equipment, e.g. such as pump stations, wet wells, sludge dewatering, manholes, air valve chambers, and sludge trans-shipment operations from silo into trucks. Sewage odor consists of mainly hydrogen sulphide & H2S is dangerous to be released to the environment. Hydrogen sulphide, the gas, also contains organic sulphur components (mercaptans, hydrocarbons) and ammonia. Odor control technologies can be grouped into three distinct categories: 1. Chemical Absorption (acid and caustic wet scrubbing) 2. Biological Oxidation (bio-filtration and bio-scrubbing / bio trinkling filtration) 3. Adsorption (activated carbon and other adsorptive medias) 4. The Combination of above systems are usually used for Biological Oxidation & Chemical Scrubbing Chemical Absorption: Chemical scrubbers achieve odor removal by mass transfer absorption via contact of air stream with aqueous solution on random packing material in a scrubbing chamber. The liquid is typically water, adjusted to the proper pH and CHEMICAL DOSING oxidation potential by chemicals. TANK CHEMICAL STORAGE TANK CHEMICAL Two parameters define the performance of any absorption SCRUBBER scrubbing system.
    [Show full text]
  • Gas Scrubbers
    Bulletin 7-S Gas Scrubbers INTRODUCTION The use of wet scrubbers for control of air pollution has gained wide acceptance throughout the industry. The ejector-venturi wet scrubber provides a number of advantages over many of the conventional single-purpose devices available. Particulate collectors such as cyclones and electrostatic precipitators cannot efficiently absorb gases or remove odors. Fabric filters, by design, cannot cope with gas streams having a high moisture content and are often affected by highly corrosive gases. Catalytic incinerators can be quickly poisoned by certain organic wastes. On the other hand, ejector-venturi gas scrubbers are very effective at removing noxious gases, particulates, odors, fumes and dusts from gas streams. Particulate contaminants are removed through impaction by the high velocity spray of scrubbing liquid. Gases and odors are eliminated through absorption and/or chemical reaction between the gases and scrubbing liquid. When properly matched to the application, these scrubbers, by their nature, are better able to cope with the high temperatures and corrosive conditions often encountered. Schutte & Koerting has over sixty years of experience in the control of commercial and industrial air pollution using wet scrubber technology. The ejector-venturi gas Description Page scrubbers described on the following pages have been Fig. 7010 Ejector-Venturi Scrubber 2 engineered to operate effectively in a variety of Fig. 7040 Separators 2 applications. Using the same basic design, these standard Fig. 7019 Vent Gas Scrubber System 2 scrubbers can be sized to meet volume requirements from Stock Systems 2 a few CFM to thousands of CFM. This broad applicability Fig. 7014 Scrubber-Separator System 3 permits Schutte & Koerting to stock these scrubbers in a Economical Stock Systems 3 wide range of sizes and materials.
    [Show full text]
  • Lime / Limestone Wet Scrubbing System for Flue Gas Desulfurization
    Application Data Sheet ADS 4900-02/rev.D Power Industry December 2014 Lime / Limestone Wet Scrubbing System for Flue Gas Desulfurization BACKGROUND will therefore add more lime when pH drops below 12 and a limestone based system will be controlled around 6. Unless Wet scrubbers are used in utilities, paper mills, and chemical one or the other is added, the SO gas will quickly drive the plants to remove sulfur dioxide (SO ) and other pollutants 2 2 pH acidic. from gas streams. Undesirable pollutants are removed by contacting the gases with an aqueous solution or slurry The calcium compounds produced in scrubbers tend to containing a sorbent. The most common sorbents are lime accumulate in recirculation loops and can cause a buildup of scale. Scale on the spray nozzles affects the atomization (Ca[OH]2) and limestone (CaCO3). Rosemount Analytical pH equipment is used to control the feed rate of these of the water droplets and reduces the scrubbing efficiency. chemicals. Scale on the return piping reduces flow rate and changes the thermal balance of the system. The tendency to scale is limited by additives such as chelating agents and phos- PROCESS phates, but these additives are generally only effective at After fly ash removal, the flue gas (seen in Figure 1) is bubbled higher pH levels. pH control is necessary to forestall the through the scrubber, and the slurry is added from start of scaling, as it is much easier to prevent scaling than above.The lime or limestone reacts with the SO2 in the flue to remove it.
    [Show full text]
  • Air/Gas Cleaning & Odor Control
    Air/Gas Cleaning & Odor Control Air/Gas Cleaning & Odor Control The Monroe Advantage For over forty years, Monroe Environmental has been designing and manufacturing air quality systems for industrial manufacturers, government agencies, and municipal treatment plants. Table of Complete Air Quality Solutions Contents Monroe Environmental offers a broad range of stand-alone equipment as well as complete 2 The Monroe systems to effectively manage dust, mist, odors, and Advantage fumes associated with both industrial manufactur- 4 Scrubbing ing and municipal water/wastewater treatment. Applications Monroe continues to solve challenging air 6 Packed Bed and gas cleaning problems with our skilled team of engineers, shop technicians, and knowledgeable Fume Scrubbers sales staff. The largest manufacturing companies in 8 Venturi the world routinely look to Monroe to solve their Particulate most demanding mist, dust, and fume control Scrubbers problems. 10 Carbon Monroe Systems and Services Adsorbers Packed Bed Wet Air Scrubbers 15,000 CFM Packed Bed Scrubber to remove ethylene • glycol and NMP fumes from a glass coating operation 12 Multi-Stage • Venturi Particulate Scrubbers Scrubbing • Carbon Adsorbers • Design and manufacture new air quality and odor control systems Systems • Multi-Stage Scrubbing Systems Retrofit existing systems to maximize 14 Mist and Dust Dust Collectors • • performance and removal efficiency Collection • Oil Mist Collectors • Ductwork design 16 Dry Dust • Permit assistance for EPA compliance Collectors • Industrial and municipal
    [Show full text]
  • Design Guidelines for Carbon Dioxide Scrubbers I
    "NCSCTECH MAN 4110-1-83 I (REVISION A) S00 TECHNICAL MANUAL tow DESIGN GUIDELINES FOR CARBON DIOXIDE SCRUBBERS I MAY 1983 REVISED JULY 1985 Prepared by M. L. NUCKOLS, A. PURER, G. A. DEASON I OF * Approved for public release; , J 1"73 distribution unlimited NAVAL COASTAL SYSTEMS CENTER PANAMA CITY, FLORIDA 32407 85. .U 15 (O SECURITY CLASSIFICATION OF TNIS PAGE (When Data Entered) R O DOCULMENTATIONkB PAGE READ INSTRUCTIONS REPORT DOCUMENTATION~ PAGE BEFORE COMPLETING FORM 1. REPORT NUMBER 2a. GOVT AQCMCSION N (.SAECIP F.NTTSChALOG NUMBER "NCSC TECHMAN 4110-1-83 (Rev A) A, -NI ' 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED "Design Guidelines for Carbon Dioxide Scrubbers '" 6. PERFORMING ORG. REPORT N UMBER A' 7. AUTHOR(&) 8. CONTRACT OR GRANT NUMBER(S) M. L. Nuckols, A. Purer, and G. A. Deason 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT. TASK AREA 6t WORK UNIT NUMBERS Naval Coastal PanaaLSystems 3407Project CenterCty, S0394, Task Area Panama City, FL 32407210,WrUnt2 22102, Work Unit 02 II. CONTROLLING OFFICE NAME AND ADDRE1S t2. REPORT 3ATE May 1983 Rev. July 1985 13, NUMBER OF PAGES 69 14- MONI TORING AGENCY NAME & ADDRESS(if different from Controtling Office) 15. SECURITY CLASS. (of this report) UNCLASSIFIED ISa. OECL ASSI FICATION/DOWNGRADING _ __N•AEOULE 16. DISTRIBUTION STATEMENT (of thia Repott) Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If different from Report) IS. SUPPLEMENTARY NOTES II. KEY WORDS (Continue on reverse side If noceassry and Identify by block number) Carbon Dioxide; Scrubbers; Absorption; Design; Life Support; Pressure; "Swimmer Diver; Environmental Effects; Diving., 20.
    [Show full text]
  • Evaluating the Effectiveness of Scrubber Installation on Sulfur Dioxide Emissions from Coal Electricity Generating Units
    Evaluating the Effectiveness of Scrubber Installation on Sulfur Dioxide Emissions from Coal Electricity Generating Units Jayson Toweh Submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Health Harvard T.H. Chan School of Public Health Boston, MA August 16, 2019 2 Abstract Background: Electricity generated by coal represents the second-largest contribution to the United States energy portfolio. Resulting emissions, such as sulfur dioxide (SO2) can lead to various adverse health impacts. Research Question: The goal of this study was to evaluate how SO2 scrubber installation affected SO2 emissions from electricity generating units (EGUs). EGU characteristics were analyzed to determine what led EGUs to install scrubbers and the types of scrubbers that were installed. Methods: EPA Air Markets Program Data was analyzed to compare emissions from EGUs that installed SO2 scrubbers between 1995-2015, to EGUs that had no scrubbers. We evaluated emissions changes from three years before to three years of post- scrubber installation. The HYSPLIT Average Dispersion metric model was used to map exposure concentration a year post scrubber installation. Results: SO2 emissions three years post-installation were 10% the levels of three years before installation. Locations in the eastern United States experienced the most significant reduction in exposure from coal EGUs. Wet Limestone scrubbers were installed most frequently contributing to the significant decrease. Discussion: The most extensive and highest emitting EGUs installed scrubbers and some of the best scrubber technology. Finding incentives to increase scrubber installation in lower generating EGUs is critical moving forward. 3 Introduction Electricity Generating Units Emissions Coal power plants are the second-largest contributor to the United States electricity supply, with 1,146 billion kWh produced equating to 27.4% of the energy generated in 2018 (EIA, 2019).
    [Show full text]
  • INVESTIGATION of POLYCYCLIC AROMATIC HYDROCARBONS (Pahs) on DRY FLUE GAS DESULFURIZATION (FGD) BY-PRODUCTS
    INVESTIGATION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) ON DRY FLUE GAS DESULFURIZATION (FGD) BY-PRODUCTS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Ping Sun, M.S. ***** The Ohio State University 2004 Dissertation Committee: Approved by Professor Linda Weavers, Adviser Professor Harold Walker Professor Patrick Hatcher Adviser Professor Yu-Ping Chin Civil Engineering Graduate Program ABSTRACT The primary goal of this research was to examine polycyclic aromatic hydrocarbons (PAHs) on dry FGD by-products to determine environmentally safe reuse options of this material. Due to the lack of information on the analytical procedures for measuring PAHs on FGD by-products, our initial work focused on analytical method development. Comparison of the traditional Soxhlet extraction, automatic Soxhlet extraction, and ultrasonic extraction was conducted to optimize the extraction of PAHs from lime spray dryer (LSD) ash (a common dry FGD by-product). Due to the short extraction time, ultrasonic extraction was further optimized by testing different organic solvents. Ultrasonic extraction with toluene as the solvent turned out to be a fast and efficient method to extract PAHs from LSD ash. The possible reactions of PAHs under standard ultrasonic extraction conditions were then studied to address concern over the possible degradation of PAHs by ultrasound. By sonicating model PAHs including naphthalene, phenanthrene and pyrene in organic solutions, extraction parameters including solvent type, solute concentration, and sonication time on reactions of PAHs were examined. A hexane: acetone (1:1 V/V) ii mixture resulted in less PAH degradation than a dichloromethane (DCM): acetone (1:1 V/V) mixture.
    [Show full text]
  • A Review of the Scrubber As a Tool for the Control of Flue Gas Emissions in a Combustion System
    EJERS, European Journal of Engineering Research and Science Vol. 4, No. 11, November 2019 A Review of the Scrubber as a Tool for the Control of flue Gas Emissions in a Combustion System N. Harry-Ngei, I. Ubong, and P. N. Ede Depending on the design, specific factors govern the Abstract—This paper focuses on the description, function application and operation of the scrubber; reference [4] and working principles of the wet gas scrubber required to listed the following vital variables to look out for in control air pollution emissions from a combustion system of a deciding the optimal scrubber for use: boiler. Important points to note in the selection and operation i. Characteristics of the particulate matter of the scrubber as well as the different types of scrubbers commonly deployed in the industries to cut down on emissions considered to be removed were addressed. A comprehensive review of the removal ii. The size categorization of the particulate matter mechanisms and schemes of the scrubber were reported for iii. Concentration of the emission in the flue gas various research on the subject. The packed tower scrubber, iv. Characteristics of the scrubber liquid, for however, was recommended because of varying advantages example, whether it is flammable or combustible and ease of operations. v. Desired removal efficiency Index Terms—Scrubber, Gas Emission, Combustion, vi. Important actual process parameters of the flue Environmental Pollution. gas as this will determine the scrubber sizing vii. Required space for the scrubber The potency and quality of separation and cleaning of I. INTRODUCTION flue gases with regards to air pollution control is depended Reference [1] described scrubbers as devices utilised to on the solvent, therefore, the characteristics, operation, remove gaseous constituents that has debilitating effects on optimum condition must be evaluated before a choice is the environment.
    [Show full text]