DOCSLIB.ORG

Distillation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Distillation Distillation Introduction Distillation is the thermal process used to separate or purify liquid mixtures. There are two big categories of distillation: simple distillation based on one-stage equilibrium and the fractional distillation (fractionation) based on multiple-stage equilibrium. In our laboratory exercise, we will be doing a multiple-stage equilibrium distillation of biofuel-water mixture. The objective here is to distill ethanol from the mixture to produce concentrated ethanol, which can be further processed to be used as biofuel or biochemical. A schematic diagram of a multiple-stage fractional distillation is shown in Figure 1. Here the feed F (mol/h) at a known initial concentration of ethanol (mole fraction) (xF) enters the distillation column at some intermediate tray (stage). The boiled vapor and the liquid are in equilibrium on each tray in the column, the vapor moving up the column and the liquid down the column through the sieve trays ensuring good contact between the two reaching equilibrium. The distilled vapor is condensed (using cold water in heat exchanger) in a condenser in the top, part of it is recycled back to the column (L (mol/h)) and the distillate product D (mol/hr) at a higher concentration of ethanol (xD) is removed from the top. The majority liquid that is flowing down the column is heated in a reboiler and the vapor returned back to the column while removing some portion as bottom product W (mol/h) at an ethanol concentration (xw). Figure 1. Multiple-stage fractional distillation (single) column with reflux Figure 2 is another schematic of the fractional multiple-stage distillation showing the trays inside and the vapor and liquid flows. Here, the section above the feeding position is call enriching section while the section below the feeding position is call stripping section. There are several sieve trays installed inside. The vapor and the liquid from each stage/tray flow countercurrent to each other. The liquid in a stage flows to the stage below and the vapor from a stage flows through the pores of sieve upward to the stage above. Hence, in each stage a vapor stream and a liquid stream are mixed, and a vapor and a liquid stream leave in equilibrium. 1 Figure 2. Fractional distillation with sieve trays or stages Some of the key assumptions in distillation are that there is equilibrium between the vapor and liquid leaving the tray; for ideal mixtures this can be described by Raoult’s law. The latent heats of vaporization of the components being distilled are approximately the same. So, the energy needed for vaporizing 1 mol of component A is the same as energy released from condensing 1 mol of component B. This results in a constant equimolar counter flow assumption in distillation. Figure 3 shows the vapor liquid equilibrium diagram for ethanol-vapor mixture. Figure 3. Vapor Liquid Equilibrium (VLE) diagram for ethanol-water system. x is the mole fraction of ethanol in the liquid phase and y is the mole fraction of ethanol in the vapor phase – they both are in equilibrium. Blue is the equilibrium line and Red is the 45◦ line. 2 As you can see in Figure 3 above about 0.8 mole fraction of ethanol in the liquid mixture (x) there is an azeotrope formed; beyond which the mole fractions of ethanol in the liquid and vapor phases are the same. Hence, they cannot be further purified or concentrated. For an ideal system, using Raoult’s law the relationship between mole fractions and partial pressures for a binary system can be given as, yA = xA PA*/P yB = xB PB*/P Where xA, xB are the mole fractions of components A and B in the liquid phase in a binary mixture Where yA, yB are the mole fractions of components A and B in the vapor phase in a binary mixture PA* and PB* are the saturation vapor pressures of pure component A and B at a given temperature P is the total pressure in the vapor phase. General format of above equations: * yi =Pi /P= xiPi /P where yi is the mole fraction of component i (A or B) in the vapor phase. For a binary mixture of A and B, the relative volatility of component A with respect to B is defined as: / / / 1 /1 ∗ ∗ So, / 11 where (For simplicity, the subscript “AB” is usually omitted for a binary system). Separation factor The separation factor of ethanol (over water) for the distillation is defined as / / where WEtOH and WH2O are concentrations of ethanol and water (in wt%) in the top product (D) and feed (F), respectively. Overall Material Balance 3 Using the nomenclature used in Figure 1, the overall material balance and component balance for the whole distillation column can be given as follows: F = D + W (overall total material balance) FxF = DxD + WxW (overall material balance on A) The overall material balance equations can be used to determine two unknown variables of D, xD , W, xW (F and xF are usually given)for designing distillation columns. For the distillation laboratory experiment, D, xD, W, xW are measured, (F and xF are known, can also be measured) and the overall material balance and component balance can be used to verify the accuracy of your measurements. An important operating parameter Reflux Ratio (R) is defined as R = L/D where, L= amount of the top condensate that is recycled back to the column (mol/h) D= amount of the top condensate that is removed from the top (mol/h) For more detailed description on the theory and operation of distillation column please see the more detailed notes as well as the reference book. Calculations and Reporting 1) In our laboratory exercise, we will be conducting multiple-stage distillation of ethanol-water mixture at a known initial concentration in the feed xF (approximate initial concentration is known, but still need to analyze its accurate concentration), constant feed flow rate F (mol/h), reboiler temperature (T) and at a reflux ratio (R). After reaching equilibrium, you will be measuring the temperature profile across the various stages including the top and bottom, pressure drop across the column and the amount of energy supplied to the heater in the reboiler Q (J/h). We will be taking samples of the feed, top product (distillate), bottoms product and measuring their ethanol concentration using specific gravity and Gas Chromatography measurements. We will also be measuring the flow rate of the top product and the bottom product. 2) To check concentrations and top and bottom product flow rate, conduct an overall material balance of the system and a component balance for ethanol and water separately and show that they are in balance. If not, explain why there may be a discrepancy. 3) Based on the temperature profile and pressure data measured and using the Txy data of the ethanol- water system (data of the boiling point diagram, given in the file “TxyEthanolWaterSystem.xlsx”) for ethanol-water mixture, calculate and plot the equilibrium concentrations of ethanol and water at various stages of the distillation column including the top condenser and the bottom. Compare the concentrations of the top condenser and the bottom against the experimentally determined values (measured by GC etc.). 4) Determine the relative volatility of the ethanol-water system at various stages of the distillation column using the vapor and liquid mole fractions calculated in 3). 5) Calculate the Separation Factor for the distillation column after reaching equilibrium under these experimental conditions. 4 5) Another complete experimental data set obtained at reflux ratio different from yours will be provided to you. Conduct the above calculations at two different reflux ratios (R), compare the performance, and determine the effect of reflux ratio on the overall distillation column performance. Some of the parameters used to compare performance include concentrations (mole fractions) in the top and bottom products, heat duty supplied to the reboiler and top and bottom product flow rate. NOTE that the reflux percent (R%) shown on the display panel and in the data acquisition software of our distillation system is the total condensate of the top condenser, i.e., R% = L/(L + D) * 100. You need to convert all R% values into R (= L/D), which is the real reflux ratio (here on mass basis). Files to submit include: (1) Your Full report in the name of YourGroupName_Distillation_YourName.pdf, e.g., Group3_Distillation_John.pdf (2) Your excel file in the name of, e.g., Group3_Distillation_John.xls (3) Raw data in the name of, e.g., Group3_Distillation_Rawdata.xls (one group only need to submit one raw data file, but each of you can always submit it and I’ll keep one copy only) References [1] Distillation Laboratory Experiment manual, GUNT [2] Christie J. Geankoplis, Transport Processes and Separation Process Principles 4th Edition [3] Distillation Theory and Operation class notes 5 .
Load more

Recommended publications
  • Extraction of Wax from Sorghum Bran •
    i EXTRACTION OF WAX FROM SORGHUM BRAN • 1 HSIEN-WEN HSU <& . ***£/ B. S., National Taiwan University, China, 1951 A THESIS » submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE - Department of Chemical Engineering KANSAS STATE COLLEGE OF AGRICULTURE AND APPLIED SCIENCE - 1955 » k Lo i~i ii Q^cu^v^Js TABLE OF CONTENTS INTRODUCTION 1 PREVIOUS WORK 3 MATERIALS 6 GLASS SOXHLET EXTRACTION AND ANALYSIS OF WAX AND OIL IN MISCELLA 7 Procedure of Using Soxhlet Extractor 7 Separation of Wax from Oil by the Acetone Method.. 8 Summary of Results 9 PILOT PLANT EXTRACTION 15 SEPARATION OF WAX AND OIL 16 Effect of Temperature in the Acetone Method 16 Urea Complex Method of Separation. 17 Theory 17 Experimental Procedure 22 Summary of Results 26 COST ESTIMATION OF A WAX RECOVERY PLANT 29 DISCUSSION 30 CONCLUSIONS 35 ACKNOWLEDGMENTS 36 BIBLIOGRAPHY 37 APPENDIX 39 INTRODUCTION i One of the functions of the Agricultural Experiment Station is the never ending search for means of better and fuller utilization of the agri- cultural products that are of particular interest in the state of Kansas. In line with this broad objective, the extraction of economically valuable lipid materials from the sorghum bran has been studied in several theses in the Departments of Chemical Engineering and Chemistry in recent years. Generally the emphasis has b. en placed upon either the chemical and physical properties of these lipides or the equipment design and performance for the solvent ex- traction operation. A brief review of the previous work is presented in the ensuing section.
    [Show full text]
  • The Separation of Three Azeotropes by Extractive Distillation by An-I Yeh A
    The separation of three azeotropes by extractive distillation by An-I Yeh A thesis submitted in partial fulfillment of the requirement for the degree of Master of Science in Chemical Engineering Montana State University © Copyright by An-I Yeh (1983) Abstract: Several different kinds of extractive distillation agents were investigated to affect the separation of three binary liquid mixtures, isopropyl ether - acetone, methyl acetate - methanol, and isopropyl ether - methyl ethyl ketone. Because of the small size of the extractive distillation column, relative volatilities were assumed constant and the Fenske equation was used to calculate the relative volatilities and the number of minimum theoretical plates. Dimethyl sulfoxide was found to be a good extractive distillation agent. Extractive distillation when employing a proper agent not only negated the azeotropes of the above mixtures, but also improved the efficiency of separation. This process could reverse the relative volatility of isopropyl ether and acetone. This reversion was also found in the system of methyl acetate and methanol when nitrobenzene was the agent. However, normal distillation curves were obtained for the system of isopropyl ether and methyl ethyl ketone undergoing extractive distillation. In the system of methyl acetate and methanol, the relative volatility decreased as the agents' carbon number increased when glycols were used as the agents. In addition, the oxygen number and the locations of hydroxyl groups in the glycols used were believed to affect the values of relative volatility. An appreciable amount of agent must be maintained in the column to affect separation. When dimethyl sulfoxide was an agent for the three systems studied, the relative volatility increased as the addition rate increased.
    [Show full text]
  • Distillation 65 Chem 355 Jasperse DISTILLATION
    Distillation 65 Chem 355 Jasperse DISTILLATION Background Distillation is a widely used technique for purifying liquids. The basic distillation process involves heating a liquid such that liquid molecules vaporize. The vapors produced are subsequently passed through a water-cooled condenser. Upon cooling, the vapor returns to it’s liquid phase. The liquid can then be collected. The ability to separate mixtures of liquids depends on differences in volatility (the ability to vaporize). For separation to occur, the vapor that is condensed and collected must be more pure than the original liquid mix. Distillation can be used to remove a volatile solvent from a nonvolatile product; to separate a volatile product from nonvolatile impurities; or to separate two or more volatile products that have sufficiently different boiling points. Vaporization and Boiling When a liquid is placed in a closed container, some of the molecules evaporate into any unoccupied space in the container. Evaporation, which occurs at temperatures below the boiling point of a compound, involves the transition from liquid to vapor of only those molecules at the liquid surface. Evaporation continues until an equilibrium is reached between molecules entering and leaving the liquid and vapor states. The pressure exerted by these gaseous molecules on the walls of the container is the equilibrium vapor pressure. The magnitude of this vapor pressure depends on the physical characteristics of the compound and increases as temperature increases. In an open container, equilibrium is never established, the vapor can simply leave, and the liquid eventually disappears. But whether in an open or closed situation, evaporation occurs only from the surface of the liquid.
    [Show full text]
  • Standard Operating Procedures
    Standard Operating Procedures 1 Standard Operating Procedures OVERVIEW In the following laboratory exercises you will be introduced to some of the glassware and tech- niques used by chemists to isolate components from natural or synthetic mixtures and to purify the individual compounds and characterize them by determining some of their physical proper- ties. While working collaboratively with your group members you will become acquainted with: a) Volumetric glassware b) Liquid-liquid extraction apparatus c) Distillation apparatus OBJECTIVES After finishing these sessions and reporting your results to your mentor, you should be able to: • Prepare solutions of exact concentrations • Separate liquid-liquid mixtures • Purify compounds by recrystallization • Separate mixtures by simple and fractional distillation 2 EXPERIMENT 1 Glassware Calibration, Primary and Secondary Standards, and Manual Titrations PART 1. Volumetric Glassware Calibration Volumetric glassware is used to either contain or deliver liquids at a specified temperature. Glassware manufacturers indicate this by inscribing on the volumetric ware the initials TC (to contain) or TD (to deliver) along with the calibration temperature, which is usually 20°C1. Volumetric glassware must be scrupulously clean before use. The presence of streaks or droplets is an indication of the presence of a grease film. To eliminate grease from glassware, scrub with detergent solution, rinse with tap water, and finally rinse with a small portion of distilled water. Volumetric flasks (TC) A volumetric flask has a large round bottom with only one graduation mark positioned on the long narrow neck. Graduation Mark Stopper The position of the mark facilitates the accurate and precise reading of the meniscus. If the flask is used to prepare a solution starting with a solid compound, add small amounts of sol- vent until the entire solid dissolves.
    [Show full text]
  • Alembic Pot Still
    ALEMBIC POT STILL INSTRUCTION MANUAL CAN BE USED WITH THE GRAINFATHER OR T500 BOILER SAFETY Warning: This system produces a highly flammable liquid. PRECAUTION: • Always use the Alembic Pot Still System in a room with adequate ventilation. • Never leave the Alembic Pot Still system unattended when operating. • Keep the Alembic Pot Still system away from all sources of ignition, including smoking, sparks, heat, and open flames. • Ensure all other equipment near to the Alembic Pot Still system or the alcohol is earthed. • A fire extinguishing media suitable for alcohol should be kept nearby. This can be water fog, fine water spray, foam, dry powder, carbon dioxide, sand or dolomite. • Do not boil dry. In the event the still is boiled dry, reset the cutout button under the base of the still. In the very unlikely event this cutout fails, a fusible link gives an added protection. IN CASE OF SPILLAGE: • Shut off all possible sources of ignition. • Clean up spills immediately using cloth, paper towels or other absorbent materials such as soil, sand or other inert material. • Collect, seal and dispose accordingly • Mop area with excess water. CONTENTS Important points before getting started ............................................................................... 3 Preparing the Alembic Pot Still ................................................................................................. 5 Distilling a Whiskey, Rum or Brandy .......................................................................................7 Distilling neutral
    [Show full text]
  • Minimum Reflux in Liquid–Liquid Extraction
    17th European Symposium on Computer Aided Process Engineering – ESCAPE17 V. Plesu and P.S. Agachi (Editors) © 2007 Elsevier B.V. All rights reserved. 1 Minimum Reflux in Liquid–Liquid Extraction Santanu Bandyopadhyaya and Calin-Cristian Cormosb aEnergy Systems Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400 076, India, E-mail: [email protected] bDepartment of Chemical Engineering, Faculty of Chemistry and Chemical Engineering, University "Babeş-Bolyai", Arany Janos 11, Cluj-Napoca 400028, Romania, E-mail: [email protected] Abstract In a simple countercurrent arrangement of different stages of liquid–liquid extraction operation, the richest extract leaving the operation is in equilibrium with the feed. However, by using reflux it is possible to enrich the extract further. A simple counter current liquid–liquid extraction operation with reflux is analogous in its essentials to distillation. In this paper, the method based on Invariant Rectifying-Stripping (IRS) curves, originally proposed to calculate minimum reflux and minimum energy requirement in distillation, has been extended to liquid–liquid extraction. The equivalent IRS curves for a ternary liquid–liquid extraction predicts the feed location in the counter current process. It also predicts the minimum reflux requirement for a given separation and minimum amount of solvent required. Keywords: liquid extraction, IRS curves, feed location, minimum solvent. 1. Introduction Liquid–liquid extraction is a separation process that takes advantage of the distribution of a substance between two insoluble liquids phases [1]. Feed to be separated is mixed with extracting solvent to produce a solvent-rich phase, called extract, and a solvent-lean phase, called raffinate.
    [Show full text]
  • Liquid-Liquid Extraction
    OCTOBER 2020 www.processingmagazine.com A BASIC PRIMER ON LIQUID-LIQUID EXTRACTION IMPROVING RELIABILITY IN CHEMICAL PROCESSING WITH PREVENTIVE MAINTENANCE DRIVING PACKAGING SUSTAINABILITY IN THE TIME OF COVID-19 Detecting & Preventing Pressure Gauge AUTOMATIC RECIRCULATION VALVES Failures Schroedahl www.circor.com/schroedahl page 48 LOW-PROFILE, HIGH-CAPACITY SCREENER Kason Corporation www.kason.com page 16 chemical processing A basic primer on liquid-liquid extraction An introduction to LLE and agitated LLE columns | By Don Glatz and Brendan Cross, Koch Modular hemical engineers are often faced with The basics of liquid-liquid extraction the task to design challenging separation While distillation drives the separation of chemicals C processes for product recovery or puri- based upon dif erences in relative volatility, LLE is a fication. This article looks at the basics separation technology that exploits the dif erences in of one powerful and yet overlooked separation tech- the relative solubilities of compounds in two immis- nique: liquid-liquid extraction. h ere are other unit cible liquids. Typically, one liquid is aqueous, and the operations used to separate compounds, such as other liquid is an organic compound. distillation, which is taught extensively in chemical Used in multiple industries including chemical, engineering curriculums. If a separation is feasible by pharmaceutical, petrochemical, biobased chemicals distillation and is economical, there is no reason to and l avor and fragrances, this approach takes careful consider liquid-liquid extraction (LLE). However, dis- process design by experienced chemical engineers and tillation may not be a feasible solution for a number scientists. In many cases, LLE is the best choice as a of reasons, such as: separation technology and well worth searching for a • If it requires a complex process sequence (several quali ed team to assist in its development and design.
    [Show full text]
  • Reflux Condensation in Narrow Rectangular Channels with Perforated Fins Nadia Souidi, André Bontemps
    Reflux condensation in narrow rectangular channels with perforated fins Nadia Souidi, André Bontemps To cite this version: Nadia Souidi, André Bontemps. Reflux condensation in narrow rectangular channels with perforated fins. Applied Thermal Engineering, Elsevier, 2003, 23, pp.871-891. 10.1016/S1359-4311(03)00021-8. hal-00184135 HAL Id: hal-00184135 https://hal.archives-ouvertes.fr/hal-00184135 Submitted on 19 Feb 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Reflux condensation in narrow rectangular channels with perforated fins N. Souidi a, A. Bontemps b,* a GRETh-CEA Grenoble, 17 Rue des Martyrs, 38054 Grenoble Cedex 9, France b LEGI-GRETh, Universitee Joseph Fourier, 17 Rue des Martyrs, 38054 Grenoble Cedex 9, France Reflux condensation is an industrial process that aims to reduce the content of the less volatile com- ponent or to eliminate the non-condensable phase of a vapour mixture, by the means of separation. Separation consists in condensing the less volatile phase and to recover the condensate while simulta- neously, the non-condensable species are recuperated at the top of the system. Compact plate-fin heat exchangers can be used in gas separation processes.
    [Show full text]
  • Laboratory Rectifying Stills of Glass 2
    » LABORATORY RECTIFYING STILLS OF GLASS 2 By Johannes H. Bruun 3 and Sylvester T. Schicktanz 3 ABSTRACT A complete description is given of a set of all-glass rectifying stills, suitable for distillation at pressures ranging from atmospheric down to about 50 mm. The stills are provided with efficient bubbling-cap columns containing 30 to 60 plates. Adiabatic conditions around the column are maintained by surrounding it with a jacket provided with a series of independent electrical heating units. Suitable means are provided for adjusting or maintaining the reflux ratio at the top of the column. For the purpose of conveniently obtaining an accurate value of the true boiling points of the distillates a continuous boiling-point apparatus is incor- porated in the receiving system. An efficient still of the packed-column type for distillations under pressures less than 50 mm is also described. Methods of operation and efficiency tests are given for the stills. CONTENTS Page I. Introduction 852 II. General features of the still assembly 852 III. Still pot 853 IV. Filling tube and heater for the still pot 853 V. Rectifying column 856 1. General features 856 2. Large-size column 856 3. Medium-size column 858 4. Small-size column 858 VI. Column jacket 861 VII. Reflux regulator 861 1. With variable reflux ratio 861 2. With constant reflux ratio 863 VIII. The continuous boiling-point apparatus 863 IX. Condensers and receiver 867 X. The mounting of the still 867 XI. Manufacture and transportation of the bubbling-cap still 870 XII. Operation of the bubbling-cap still 870 XIII.
    [Show full text]
  • Selection of Thermodynamic Methods
    P & I Design Ltd Process Instrumentation Consultancy & Design 2 Reed Street, Gladstone Industrial Estate, Thornaby, TS17 7AF, United Kingdom. Tel. +44 (0) 1642 617444 Fax. +44 (0) 1642 616447 Web Site: www.pidesign.co.uk PROCESS MODELLING SELECTION OF THERMODYNAMIC METHODS by John E. Edwards [email protected] MNL031B 10/08 PAGE 1 OF 38 Process Modelling Selection of Thermodynamic Methods Contents 1.0 Introduction 2.0 Thermodynamic Fundamentals 2.1 Thermodynamic Energies 2.2 Gibbs Phase Rule 2.3 Enthalpy 2.4 Thermodynamics of Real Processes 3.0 System Phases 3.1 Single Phase Gas 3.2 Liquid Phase 3.3 Vapour liquid equilibrium 4.0 Chemical Reactions 4.1 Reaction Chemistry 4.2 Reaction Chemistry Applied 5.0 Summary Appendices I Enthalpy Calculations in CHEMCAD II Thermodynamic Model Synopsis – Vapor Liquid Equilibrium III Thermodynamic Model Selection – Application Tables IV K Model – Henry’s Law Review V Inert Gases and Infinitely Dilute Solutions VI Post Combustion Carbon Capture Thermodynamics VII Thermodynamic Guidance Note VIII Prediction of Physical Properties Figures 1 Ideal Solution Txy Diagram 2 Enthalpy Isobar 3 Thermodynamic Phases 4 van der Waals Equation of State 5 Relative Volatility in VLE Diagram 6 Azeotrope γ Value in VLE Diagram 7 VLE Diagram and Convergence Effects 8 CHEMCAD K and H Values Wizard 9 Thermodynamic Model Decision Tree 10 K Value and Enthalpy Models Selection Basis PAGE 2 OF 38 MNL 031B Issued November 2008, Prepared by J.E.Edwards of P & I Design Ltd, Teesside, UK www.pidesign.co.uk Process Modelling Selection of Thermodynamic Methods References 1.
    [Show full text]
  • Distillation Theory
    Chapter 2 Distillation Theory by Ivar J. Halvorsen and Sigurd Skogestad Norwegian University of Science and Technology Department of Chemical Engineering 7491 Trondheim, Norway This is a revised version of an article published in the Encyclopedia of Separation Science by Aca- demic Press Ltd. (2000). The article gives some of the basics of distillation theory and its purpose is to provide basic understanding and some tools for simple hand calculations of distillation col- umns. The methods presented here can be used to obtain simple estimates and to check more rigorous computations. NTNU Dr. ing. Thesis 2001:43 Ivar J. Halvorsen 28 2.1 Introduction Distillation is a very old separation technology for separating liquid mixtures that can be traced back to the chemists in Alexandria in the first century A.D. Today distillation is the most important industrial separation technology. It is particu- larly well suited for high purity separations since any degree of separation can be obtained with a fixed energy consumption by increasing the number of equilib- rium stages. To describe the degree of separation between two components in a column or in a column section, we introduce the separation factor: ()⁄ xL xH S = ------------------------T (2.1) ()x ⁄ x L H B where x denotes mole fraction of a component, subscript L denotes light compo- nent, H heavy component, T denotes the top of the section, and B the bottom. It is relatively straightforward to derive models of distillation columns based on almost any degree of detail, and also to use such models to simulate the behaviour on a computer.
    [Show full text]
  • Distillation ­ Accessscience from Mcgraw­Hill Education
    6/19/2017 Distillation ­ AccessScience from McGraw­Hill Education (http://www.accessscience.com/) Distillation Article by: King, C. Judson University of California, Berkeley, California. Last updated: 2014 DOI: https://doi.org/10.1036/1097­8542.201100 (https://doi.org/10.1036/1097­8542.201100) Content Hide Simple distillations Fractional distillation Vapor­liquid equilibria Distillation pressure Molecular distillation Extractive and azeotropic distillation Enhancing energy efficiency Computational methods Stage efficiency Links to Primary Literature Additional Readings A method for separating homogeneous mixtures based upon equilibration of liquid and vapor phases. Substances that differ in volatility appear in different proportions in vapor and liquid phases at equilibrium with one another. Thus, vaporizing part of a volatile liquid produces vapor and liquid products that differ in composition. This outcome constitutes a separation among the components in the original liquid. Through appropriate configurations of repeated vapor­liquid contactings, the degree of separation among components differing in volatility can be increased manyfold. See also: Phase equilibrium (/content/phase­equilibrium/505500) Distillation is by far the most common method of separation in the petroleum, natural gas, and petrochemical industries. Its many applications in other industries include air fractionation, solvent recovery and recycling, separation of light isotopes such as hydrogen and deuterium, and production of alcoholic beverages, flavors, fatty acids, and food oils. Simple distillations The two most elementary forms of distillation are a continuous equilibrium distillation and a simple batch distillation (Fig. 1). http://www.accessscience.com/content/distillation/201100 1/10 6/19/2017 Distillation ­ AccessScience from McGraw­Hill Education Fig. 1 Simple distillations. (a) Continuous equilibrium distillation.
    [Show full text]