DOCSLIB.ORG

Chapter 2: Separation Factor and Molecular Properties

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chapter 2: Separation Factor and Molecular Properties Unit Operation Design Chapter 2: Separation Factor and Molecular Properties Dr. S.H. Esmaeili-Faraj Molecular weight Molecular volume Properties of Chemical reaction equilibrium pure Acidic Molecular shape groups substances Basic groups Ionization depends Molecular charge (e.g. -COOH and -NH2 in proteins) on pH Dipole moment & polarizability Groups like O-H and C=O in molecules are polar. The molecule Such groups present in an asymmetrical fashion exhibits a finite within a molecule dipole moment Polar molecules interact more strongly with other molecules than nonpolar molecules of the same size do. Polar substance, e.g., water has a lower vapor pressure than a nonpolar species of about the same molecular weight, e.g., methane. The tendency for a dipole to be induced in a molecule of that substance Depends upon the size of molecule and the mobility of electrons Electrons in aromatic rings and, to a lesser extent, olefinic bonds are more mobile than the electrons in single covalent bonds and therefore impart a greater polarizability. Greater More Lower vapor solubility in polarizable pressure molecule polar solvent Interaction with mass separating Properties of pure substances agent or barier Dipole moment Chemical Molecular Molecular Molecular Molecular Molecular Dipole Moment & Separation process & reaction size & weight volume shape charge polarizability polarizability equilibrium shape Distillation 2 3 4 2 - - - - Crystallization 4 2 2 3 2 - - - Clathration - - - - - 3 1 3 Solvent extraction & - - - - - 2 3 2 absorption Ordinary adsorption - - - - - 2 2 2 Adsorption with - - - - - - 1 3 molecular sieves Dialysis; gel - 2 3 - - - 1 3 permeation Ultrafiltration - - 4 - - - 1 - Gaseous diffusion 1 - - - - - - - Sweep diffusion 2 2 - - - - - - Ultracentrifugation 1 - - - - - - - Electrophoresi 2 3 3 - 1 - - - Electrodialysis - - - - 1 - 2 - Ion exchange - - - - - 1 2 - Key: 1. primary effect; necessary for any separation 2. primary effect 3. secondary effect (perhaps through another property) 4. small effect - No effect Morphological analysis Systemically analysis of methods and alternatives for doing special case and then, review of combination of these alternatives. Producing phethalic Gasoline producing anhydride & other blending & terephethalic acid & phthalates as a conversion to dimethyl plasticizer for PVC other isomers terephethalate property O-xylene M-xylene P-xylene Ethyl benzene Percent(%) at 1000K in equilibrium mixture 23 43 19 15 Boiling point(K) 417.3 412.6 411.8 409.6 Freezing point(k) 248.1 225.4 286.6 178.4 Dipole moment (10^-18esu) 0.62 0.36 0 -------- Polarizability(10^-31m3 ) 141 141.8 142 -------- Molecular weight 106.16 106.16 106.16 106.16 Density, at 298k (g/cm^3 ) 0.8802 0.8642 0.8610 0.8670 λ,at boiling point(cal/g) 82.9 82.0 81.2 81.0 = =1.16 Dipole moment of p-xylene = 0 =1.02 p-xylene Narrow molecule Choosing a method on the basis of molecular shape m-xylene Nearly spherical difference • same molecular weights Separation processes based on Mw • different in dipole moment between ortho & meta Distillation(R=15,N≥100) • para & meta separation distillation Separation process based on molecular shape and Reactivity. Crystallization Membrane Adductive Adsorption crystallization Chemical Clathration reaction Extractive HF-BF3 crystallization The difference in molecular shapes has two effects: 1. p-xylene molecules can stack together more readily into a crystal structure because of their symmetrical shape, and as a result p-xylene has a much higher freezing point(286.6 k) 2. The difference in shape between p- and m-xylene means that m-xylene molecules cannot fit easily into the p-xylene crystal structure in the solid phase. Thus, the solid phase formed by partial freezing of a mixture of the two isomers contains essentially pure p-xylene. 100% Ortho 30.5% Para meta100% 100% • p-xylene manufacture by crystallization & isomerization. Recycled isomerized xylene Benzene Toluene Light gas feed 99% Para x crystallization s y 5% ethyl benzene product t l 23% p-xylene a e 50% m-xylene Mixed xylene(9% Para) 22% 0-xylene b n e i s l isomerization p i l z i e t r t e O-xylene r product • addition of CCl4 as separation agent. refrigeration temperature. but Recovery of p-xylene. additional stage for para xylene separation. • addition of nickel[(4-methylpyridine)4 (SCN)2 ] as a separation agent. Recovery of 92% of the p-xylene in a single stage. • addition of normal-pentane . Shifting eutectic point. • αp-o = 2.0 ; αp-m = 1.3 • low density polyethylene membrane. • disadvantages Difficulty of staging Difficulty of provision of driving force for p-xylene crossing from membrane. • molecular sieves • more than 22 new industrial units (1968-1978) Benzene product Toluene product Non aromatics Clay B T sulfolane O Light treating E Platformate N L S P L naphtha I plat former THDA T T O-xylene E poduct R P-xylene product Heavy platformate Clay PAREX isomer treating Heavy aromatic Xylene column Heavies splitter Sulfonation with cold & m- and o-isomers are sulfonated, concentrated while p-isomer is unchanged. Treatment with Elimination of and excess & formation of sodium salts of the sulfonates. Evaporative crystallization O-xylene Sodium sulfonate precipitates first. • only laboratory method. Ethyl benzene D P-xylene D I I S < .03% m-xylene S T T I I l E l L X L A HF-BF3 T A T R D T I Feed A E I O C C N Mixed O O-xylene xylene T O N P O D O R HF-BF3 E S recycle C E O R isomerization M P m- O xylene S 99.5% E Recycled isomerized xylene r • removal between 60% to 99.5% of the water Berry: fruit present. juices Juice stability. 2-3 hr @ 328k <1min @ 367k great economy in transportation & storage costs. 1s @ 389k • common process Multi-effect Reduction of steam evaporation costs. thermal sensitivity • problems build up semisolid layer next to the surface in evaporators escaping of flavor and aroma compound Improvement of evaporation process • solution Use of other separation process reduction of boiling point • vacuum evaporation reduction of residence time(A/V ) preheating by injection of steam 1.addition of fresh juice to the concentrate 2.obtaining layer material from peels , cores , & adding it to concentrate Prevention of escaping aroma 3.Separation of aroma from the water vapor & returning to concentrate 4.Use another process • first technique Product contains 10% of volatile compounds. • second technique Most successful process , difference between flavoring material in peels & juice. • third technique Essence recovery process Initial Receiving Means of creating phase of phase for water chemical potential Example water difference Liquid Vapor Pressure(vacuum) Flash evaporation Temperature Drying with (feed superheat) superheated steam Composition(carrier) Air drying Immiscible liquid Composition(solvent) Extraction solid Temperature(freeze) Freeze concentration Composition Clathration (precipitate) Composition(adsorb) Solid desiccant Initial Receiving phase Means of creating phase of for water chemical potential Example water difference solid Vapor Pressure(vacuum) Ordinary freeze-drying Composition(carrier) Carrier-gas freeze – drying Immiscible liquid Composition (solvent) ------------ Initial Receiving Means of creating phase of phase for chemical potential Example water water difference liquid Vapor Pressure(vacuum) Pervaporation with compression Temperature (feed superheat) ----------- Composition (carrier) liquid Pressure Pervaporation (pressurized feed) with carrier Reverse osmosis Composition Direct osmosis (added solute) Composition(solvent) Perstraction Initial Receiving Means of creating phase of phase for chemical potential Example water water difference Liquid ------------- Screening Pulp removal Density difference Centrifugation before evaporation solid ------------- Screening Grinding & screening for frozen juices Density difference Grinding & flotation in liquid of intermediate density for frozen juices Flash (or partial) evaporation is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. If the throttling valve or device is located at the entry into a pressure vessel so that the flash evaporation occurs within the vessel, then the vessel is often referred to as a flash drum. Ref: www.wikipedia.org If the saturated liquid is a single-component liquid (for example, liquid propane or liquid ammonia), a part of the liquid immediately "flashes" into vapor. Both the vapor and the residual liquid are cooled to the saturation temperature of the liquid at the reduced pressure. This is often referred to as "auto-refrigeration" and is the basis of most conventional vapor compression refrigeration systems. If the saturated liquid is a multi-component liquid (for example, a mixture of propane, isobutane and normal butane), the flashed vapor is richer in the more volatile components than is the remaining liquid. Ref: www.wikipedia.org A close loop pneumatic conveying type Transport steam is superheated indirectly via a tubular heat exchanger or electrical heating Only 5-60 seconds residence time, For some materials a second superheater is necessary to achieve the required dryness Separation of transport steam and the dry material in a high efficiency cyclone Reuse of the generated excess steam with a pressure of 1-5 bar, directly or after a re- SuperheatedSuperheated Steam Steam Dryer Dryer (SSD (SSD™) ™) boiler generating clean steam withwith pre pre-heater-heater and and backmixing secondary superheater
Load more

Recommended publications
  • Automobile Air Bag Inflation System Using Pressurized Carbon Dioxide Bart Adams New Jersey Institute of Technology
    New Jersey Institute of Technology Digital Commons @ NJIT Dissertations Theses and Dissertations Spring 1998 Automobile air bag inflation system using pressurized carbon dioxide Bart Adams New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/dissertations Part of the Mechanical Engineering Commons Recommended Citation Adams, Bart, "Automobile air bag inflation system using pressurized carbon dioxide" (1998). Dissertations. 939. https://digitalcommons.njit.edu/dissertations/939 This Dissertation is brought to you for free and open access by the Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Dissertations by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. Cprht Wrnn & trtn h prht l f th Untd Stt (tl , Untd Stt Cd vrn th n f phtp r thr rprdtn f prhtd trl. Undr rtn ndtn pfd n th l, lbrr nd rhv r thrzd t frnh phtp r thr rprdtn. On f th pfd ndtn tht th phtp r rprdtn nt t b “d fr n prp thr thn prvt td, hlrhp, r rrh. If , r rt fr, r ltr , phtp r rprdtn fr prp n x f “fr tht r b lbl fr prht nfrnnt, h ntttn rrv th rht t rf t pt pn rdr f, n t jdnt, flfllnt f th rdr ld nvlv vltn f prht l. l t: h thr rtn th prht hl th r Inttt f hnl rrv th rht t dtrbt th th r drttn rntn nt: If d nt h t prnt th p, thn lt “ fr: frt p t: lt p n th prnt dl rn h n tn lbrr h rvd f th prnl nfrtn nd ll ntr fr th pprvl p nd brphl th f th nd drttn n rdr t prtt th dntt f I rdt nd flt.
    [Show full text]
  • Volatile Liquid Precursors for the Chemical Vapor Deposition (Cvd) of Thin Films Containing Tungsten
    Mat. Res. Soc. Symp. Proc. Vol. 612 © 2000 Materials Research Society VOLATILE LIQUID PRECURSORS FOR THE CHEMICAL VAPOR DEPOSITION (CVD) OF THIN FILMS CONTAINING TUNGSTEN Roy G. Gordon, Seán Barry, Randy N. R. Broomhall-Dillard, Valerie A. Wagner and Ying Wang Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138 ABSTRACT A new CVD process is described for depositing conformal layers containing tungsten, tungsten nitride or tungsten oxide. A film of tungsten metal is deposited by vaporizing liquid tungsten(0) pentacarbonyl 1-methylbutylisonitrile and passing the vapors over a surface heated to 400 to 500 oC. This process can be used to form gate electrodes compatible with ultrathin dielectric layers. Tungsten nitride films are deposited by combining ammonia gas with this tungsten-containing vapor and using substrates at temperatures of 250 to 400 oC. Tungsten nitride can act as a barrier to diffusion of copper in microelectronic circuits. Tungsten oxide films are deposited by adding oxygen gas to the tungsten-containing vapor and using substrates at temperatures of 200 to 300 oC. These tungsten oxide films can be used as part of electrochromic windows, mirrors or displays. Physical properties of several related liquid tungsten compounds are described. These low-viscosity liquids are stable to air and water. These new compounds have a number of advantages over tungsten-containing CVD precursors used previously. INTRODUCTION Chemical vapor deposition (CVD) is a widely-used process for forming solid materials, such as coatings, from reactants in the vapor phase. CVD processes can have many advantages: good step coverage, dense films, high deposition rates, scalability to larger areas and low cost.
    [Show full text]
  • Bubble Growth in Superheated Solutions with a Non-Volatile Solute
    Chemical Engineering Science, Vol. 49, No.9, pp. 1301- 1)12, 1994 Copyright tJ 1994 Elsevier Science Ltd Printed in Great Britain . All rights reserved 0009- 2509/94 $6.00 + 0.00 BUBBLE GROWTH IN SUPERHEATED SOLUTIONS WITH A NON-VOLATILE SOLUTE OSAMU MIYATAKE Department of Chemical Engineering, Kyushu University, Fukuoka 812, Japan ITSUO TANAKA Division of Biological Production System, Gifu University, Gifu 501-1 I, Japan and NOAM LIOR! Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104-6315. U.SA (First received 30 April 1993; accepted in revised form 9 September 1993) Abstract-Growth of single bubbles in a uniformly superheated binary solution containing a non-volatile solute was studied both experimentally, using an aqueous solution of NaCI at mass fractions of 0.05 and 0.20, an initial temperature range of 40-80°C and an applied initial superheat range of 1.7-16.5°C, and theoretically, with very good agreement between the experimental and theoretical results. The experimental technique developed, using an electrolytically nucleated bubble, was found to be excellent for single-bubble growth studies and photography. Some of the principal conclusions are that increasing the concentration of the non-volatile solute at a given initial solution temperature reduces the bubble growth rate when the far-field pressure is dropped to a fixed value. The effect of concentration on the bubble growth rate becomes smaller when the far-field pressure is reduced to bring the solution to either a fixed superheat, or to a fixed initial pressure difference between the bubble interior and exterior, leading to a conclusion that it is preferable to study and correlate bubble growth rates by using the superheat and this pressure difference as parameters.
    [Show full text]
  • Cooling Under Vacuum
    Cooling under Vacuum GEA Wiegand GmbH Table of Contents Introduction Cooling is an expensive process. Ongoing increases in Introduction 2 energy costs demand alternatives to traditional systems Comparison between compression cooling plants (mechanical compressors). More and more, flash cooling and steam jet cooling plants 2 plants offer an environmentally friendly and economical solution. Steam Jet Cooling Plants – Construction Details GEA Wiegand has more than fifty years of experience in and How They Work 3 the design and construction of flash cooling plants. Advantages of flash cooling plants 3 Vapour compression using jet pumps 4 GEA Wiegand reference plants: Flash cooling 4 water Steam Jet Cooling Plants – Types 5 aqueous nitric acid/phosphoric acid Steam jet cooling plants of compact design 5 aqueous plaster suspension Steam jet cooling plants of column design 6 calcium milk Steam jet cooling plants of bridge design 7 barium hydroxide solutions Standardised steam jet cooling plants – sizes 8 various waste waters fruit juice Installation and Control 10 milk Possible combinations 10 glue Installation alternatives 11 Control of steam jet cooling plants 12 The steam jet cooling plants may have a capacity between Heat Recovery Plants 14 approximately 10 and 20 000 kilowatts. As an example, water may be cooled down to a temperature of approxi- Criteria for the Design mately 5 °C. of Steam Jet Cooling Plants 15 Comparison between compression cooling plants and steam jet cooling plants Type of cooling plant Compression cooling plant Steam
    [Show full text]
  • Modelling and Optimisation of Multi-Stage Flash Distillation and Reverse Osmosis for Desalination of Saline Process Wastewater Sources
    membranes Article Modelling and Optimisation of Multi-Stage Flash Distillation and Reverse Osmosis for Desalination of Saline Process Wastewater Sources Andras Jozsef Toth 1,2 1 Environmental and Process Engineering Research Group, Department of Chemical and Environmental Process Engineering, Budapest University of Technology and Economics, M˝uegyetemrkp. 3, H-1111 Budapest, Hungary; [email protected]; Tel.: +36-1-463-1490 2 Institute of Chemistry, University of Miskolc, Egyetemváros C/1 108, H-3515 Miskolc, Hungary Received: 9 August 2020; Accepted: 27 September 2020; Published: 28 September 2020 Abstract: Nowadays, there is increasing interest in advanced simulation methods for desalination. The two most common desalination methods are multi-stage flash distillation (MSF) and reverse osmosis (RO). Numerous research works have been published on these separations, however their simulation appears to be difficult due to their complexity, therefore continuous improvement is required. The RO, in particular, is difficult to model, because the liquids to be separated also depend specifically on the membrane material. The aim of this study is to model steady-state desalination opportunities of saline process wastewater in flowsheet environment. Commercial flowsheet simulator programs were investigated: ChemCAD for thermal desalination and WAVE program for membrane separation. The calculation of the developed MSF model was verified based on industrial data. It can be stated that both simulators are capable of reducing saline content from 4.5 V/V% to 0.05 V/V%. The simulation results are in accordance with the expectations: MSF has higher yield, but reverse osmosis is simpler process with lower energy demand. The main additional value of the research lies in the comparison of desalination modelling in widely commercially available computer programs.
    [Show full text]
  • Flash Evaporation Flashing Atomization Can Occur in Liquids
    Flash Evaporation experimental apparatus consists of a high pressure Flashing atomization can occur in liquids subjected tank feeding high pressure and high temperature to sudden pressure drop or sufficient superheating water to the nozzle, the liquid collecting vessel, high which leads to formation of vapor bubbles inside the speed camera and the measuring instruments at liquid. Rapid growth of bubbles is the cause of the different location of the system. The pressure is explosion of the bubble and generation of finer generated by the air above the liquid level in the tank droplets and spray. Therefore, this phenomena has which is pressurized by air pressure amplifier. This direct effect on the droplet formation and size as well apparatus, under controlled pressure and temperature as general shape of the spray. can generate a good simulation of flash evaporation In splash plate nozzles due to the high temperature in the actual splash plate nozzle. Measuring the size and pressure flashing is so likely to occur and affect and distribution of the droplets will be performed by the performance of the recovery craft boiler means of the camera and analyzing the pictures dramatically. obtained from different tests. This study is going to explore the flashing To predict the characteristics of the sheet in different evaporation in splash plate nozzles in analytical, circumstances, a theoretical approach will be experimental, and numerical ways. Studying the constructed based on theories existing in the theory and published research works related to this literature. The theory and its agreement with the area is the first step. The unknowns of the study are experimental results can enhance the legitimacy of flashing type in this nozzles, evaporation ratio, effect the results and conclusions of the study and hence a of flashing on droplet formation, size and critical step to attain the goal of the study.
    [Show full text]
  • Modeling of Flash Boiling Flows in Injectors with Gasoline-Ethanol Fuel Blends
    University of Massachusetts Amherst ScholarWorks@UMass Amherst Open Access Dissertations 2-2011 Modeling of Flash Boiling Flows in Injectors with Gasoline-Ethanol Fuel Blends Kshitij Deepak Neroorkar University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/open_access_dissertations Part of the Mechanical Engineering Commons Recommended Citation Neroorkar, Kshitij Deepak, "Modeling of Flash Boiling Flows in Injectors with Gasoline-Ethanol Fuel Blends" (2011). Open Access Dissertations. 338. https://scholarworks.umass.edu/open_access_dissertations/338 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. MODELING OF FLASH BOILING FLOWS IN INJECTORS WITH GASOLINE-ETHANOL FUEL BLENDS A Dissertation Presented by KSHITIJ NEROORKAR Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY February 2011 Mechanical and Industrial Engineering c Copyright by Kshitij Neroorkar 2011 All Rights Reserved MODELING OF FLASH BOILING FLOWS IN INJECTORS WITH GASOLINE-ETHANOL FUEL BLENDS A Dissertation Presented by KSHITIJ NEROORKAR Approved as to style and content by: David P. Schmidt, Chair Stephen de Bruyn Kops, Member Michael Henson, Member Ronald O. Grover, Jr., Member Donald Fisher, Department Head Mechanical and Industrial Engineering To my lovely family ACKNOWLEDGMENTS I would like to thank my advisor Prof. David Schmidt for his guidance and support during the course of this PhD. He has always given the highest priority to the development of his students’ careers, for which I will always be grateful.
    [Show full text]
  • Introduction to Chemical Engineering for Lecture 7: Flash Distillation
    Introduction to Chemical Engineering for Lecture 7: Flash Distillation Martin Iggland, Marco Mazzotti∗ ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 Zurich, Switzerland 1. Flash distillation Flash evaporation is one of the simplest separation processes. A liquid stream containing several components is partially vaporised in a ”flash drum" at a certain pressure and temperature. This results in two phases: a vapor phase, enriched in the more volatile components, and a liquid phase, enriched in the less volatile components. The fluid is pressurized and heated and is then passed through a throttling valve or nozzle into the flash drum. Because of the large drop in pressure, part of the fluid vaporizes. The vapor is taken off overhead, while the liquid drains to the bottom of the drum, where it is withdrawn. The system is called ”flash” distillation because the vaporization is extremely rapid after the feed enters the drum. Because of the intimate contact between liquid and vapor, the system in the flash chamber is very close to an equilibrium stage. Figure 1 shows a schematic drawing of a flash unit. As long as the feed consists of only 2 components, we have a binary flash. We will consider this case first, then we will see how to calculate bubble- and dew-points of binary mixtures. Further reading for this part of the lecture can ∗Corresponding author: phone +41 44 632 2456; fax +41 44 632 11 41. Email address: [email protected] (Marco Mazzotti) Preprint submitted to Script SS 2015 Figure 1: Schematic drawing of a flash distillation unit be found in chapter 2 of Wankat's "Separation Process Engineering" 1.
    [Show full text]
  • Mathematical Modelling of Heat Exchange in Flash Tank Heat Exchanger Cascades
    Mathematics-in-Industry Case Studies Journal, Volume 5, pp. 43-58 (2013) Mathematical modelling of heat exchange in flash tank heat exchanger cascades Andrei Korobeinikov ∗ John McCarthy y Emma Mooney z Krum Semkov x James Varghese { Abstract. Flash tank evaporation combined with a condensing heat ex- changer can be used when heat exchange is required between two streams, where at least one of these streams is difficult to handle (tends severely to scale, foul, causing blockages). To increase the efficiency of heat exchange, a cascade of these units in series can be used. Heat transfer relationships in such a cascade are very complex due to their interconnectivity; thus the impact of any changes proposed is difficult to predict. Moreover, the distribution of loads and driving forces at different stages and the number of designed stages faces tradeoffs which require fundamental understanding and balances. This paper addresses these problems, offering a mathematical model of a single unit composed of a flash tank evaporator combined with a condensing heat exchanger. This model is then extended for a chain of such units. The pur- pose of this model is an accurate study of the factors influencing efficiency of the system (maximizing heat recovery) and evaluation of the impact of an alteration of the system, thus allowing for guided design of new or redesign of existing systems. Keywords. Heat exchange, alumina production, the Bayer process, energy efficiency, energy management ∗Centre de Recerca Matematica, Campus de Bellaterra, Edifici C, 08193 Bellaterra, Barcelona, Spain. ako- [email protected] yMathematics Department, Box 1146, Washington University, St. Louis, MO 63130, USA.
    [Show full text]
  • A Simulation Model of Spray Flash Desalination System
    Proceedings of the 17th World Congress The International Federation of Automatic Control Seoul, Korea, July 6-11, 2008 A Simulation Model of Spray Flash Desalination System Satoru Goto ∗ Yuji Yamamoto ∗ Takenao Sugi ∗∗ Takeshi Yasunaga ∗∗Yasuyuki Ikegami ∗∗Masatoshi Nakamura ∗ ∗ Department of Advanced Systems Control Engineering, Saga University Honjomachi, Saga 840-8502, Japan (Tel: +81-952-28-8643; Fax: +81-952-28-8666; e-mail: [email protected]) ∗∗ Institute of Ocean Energy, Saga University Honjomachi, Saga 840-8502, Japan Abstract: In this paper, a simulation model of a spray flash desalination system is proposed. In the spray flash desalination system, the freshwater is made from the evaporation-condensation process, i.e., evaporation of warm surface seawater in a flash chamber and condensation of the generated vapor by deep cool seawater. A simulation model of the spray flash desalination system is constructed by using physical relations such as the energy conservation law and the mass conservation law. Simulation results of the proposed simulation model are compared with the experimental results of an experimental plant of the splay flash desalination system, and it shows the effectiveness of the proposed simulation model. Keywords: spray flash; desalination system; simulation model; mass conservation law; energy conservation law 1. INTRODUCTION by using the spray flash evaporation. Since the spray flash desalination method can be generated freshwater with small temperature differences, the performance analysis of the hybrid Water issue is a serious problem in the world because of the cycle with Ocean Thermal Energy Conversion (OTEC) has influence of the rapid increase in population, global warming, been examined.
    [Show full text]
  • Research Progresses of Flash Evaporation in Aerospace Applications
    Hindawi International Journal of Aerospace Engineering Volume 2018, Article ID 3686802, 15 pages https://doi.org/10.1155/2018/3686802 Review Article Research Progresses of Flash Evaporation in Aerospace Applications Wei Ma,1 Siping Zhai,2 Ping Zhang ,2 Yaoqi Xian,2 Lina Zhang,1 Rui Shi,1 Jiang Sheng,1 Bo Liu,1 and Zonglin Wu1 1Science and Technology on Space Physics Laboratory, Beijing 100076, China 2School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, China Correspondence should be addressed to Ping Zhang; [email protected] Received 7 June 2018; Accepted 10 October 2018; Published 17 December 2018 Academic Editor: André Cavalieri Copyright © 2018 Wei Ma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Liquid is overheated and evaporated quickly when it enters into the environment with lower saturation pressure than that corresponding to its initial temperature. This phenomenon is known as the flash evaporation. A natural low-pressure environment and flash evaporation have unique characteristics and superiority in high altitude and outer space. Therefore, flash evaporation is widely used in aerospace. In this paper, spray flash evaporation and jet flash evaporation which are two different forms were introduced. Later, key attentions were paid to applications of flash evaporation in aerospace. For example, the flash evaporation has been used in the thermal control system of an aircraft and the propelling system of a microsatellite and oil supply system of a rocket motor.
    [Show full text]
  • Formulas for Calculating the Approach to Equilibrium in Open Channel Flash Evaporators for Saline Water
    Desalination, 60 (1986) 223-249 223 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands Formulas for Calculating the Approach to Equilibrium in Open Channel Flash Evaporators for Saline Water NOAM LIOR Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104 (U.S.A.) (Received January 2, 1985) SUMMARY The evaporator used in multistage flash desalination plants, and considered for open cycle ocean-thermal energy conversion (OTEC) plants is the open- channel type, in which an essentially-horizontal stream of seawater is passed through an open channel in which it is exposed to a pressure lower than the saturation pressure which corresponds to its temperature. This paper reviews the equations used at present to determine the nonequilibrium allowance A' which indicates how far from equilibrium the seawater stream is as it leaves the evaporator. Flash evaporation in open channels is used in most of the water desalination plants, and the existing equations for A' have been developed for that application. The equations are typically empirical correlations, each developed for one type of geometry and range of parameters. The equations are com- pared graphically, plotted side-by-side to express A' as a function of the major parameters: stage saturation temperature, stage flash-down, flashing seawater flow rate, stage length, and flashing seawater depth. It was found for water desalination applications that there exists a large spread between the non-equilibrium fraction values calculated by the differ- ent equations, of about one order of magnitude. The situation is even worse for OTEC conditions. Consequently, it was concluded that no general method exists for the adequately accurate prediction of A', i.e.
    [Show full text]