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Sanjay M. Mahajani - One of the best experts on this subject based on the ideXlab platform.
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Transacetalization of Glycerol with Methylal by Reactive Distillation
Industrial & Engineering Chemistry Research, 2012Co-Authors: Amit Hasabnis, Sanjay M. MahajaniAbstract:The applicability of Reactive Distillation (RD) for the transacetalization of glycerol with methylal in the presence of Amberlyst-15 is studied by experiments and simulation. On the basis of the batch kinetic runs a pseudohomogeneous kinetic model is proposed. The experiments are performed on a continuous Reactive Distillation column and are compared with the predictions of the equilibrium stage model. Various feasible configurations of Reactive Distillation are identified and the experimentally validated simulator is used to investigate the effect of different design and operating parameters such as number of rectifying stages, stripping stages, feed mole ratio, reboiler duty, etc. on the performance in each case. The RD process alternatives and the conventional process of reaction followed by Distillation are compared.
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Entrainer-Based Reactive Distillation for Esterification of Glycerol with Acetic Acid
Industrial & Engineering Chemistry Research, 2010Co-Authors: Amit Hasabnis, Sanjay M. MahajaniAbstract:The applicability of Reactive Distillation for esterification of glycerol with acetic acid in the presence of Amberlyst-15 as catalyst and ethylene dichloride as an entrainer is evaluated through experiments and simulation. The reaction is studied in both semibatch and continuous Reactive Distillation systems. The effect of different parameters such as entrainer amount, catalyst loading, and reboiler duty is studied. The results indicate that entrainer-based semibatch Reactive Distillation can enhance the selectivity toward triacetin to about 100%, which is much greater than that offered by any conventional reactor with stoichiometric mole ratio of reactants. Simulations for both semibatch and continuous Reactive Distillation are performed, and results agree reasonably well with those obtained by experiments. The best possible design and operating parameters are obtained through detailed simulation using an experimentally validated model. A column configuration is recommended for a continuous process.
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Reactive Distillation with side draw
Chemical Engineering and Processing: Process Intensification, 2009Co-Authors: Suman Thotla, Sanjay M. MahajaniAbstract:We demonstrate the applicability of a new Reactive Distillation configuration, i.e. Reactive Distillation with side draw, for certain industrially important reactions. For the reacting systems which involve products with intermediate volatility, a side draw facilitates its in situ removal and enhances either conversion or selectivity. It further reduces the downstream processing in some cases. The concept is proved for three representative systems, viz. esterification of lactic acid, aldol condensation of acetone and for esterification of fatty acid by methanol. Experimental proof is also provided in some cases.
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Esterification of Lactic Acid with n-Butanol by Reactive Distillation
Industrial & Engineering Chemistry Research, 2007Co-Authors: Rakesh Kumar, Sanjay M. MahajaniAbstract:Esterification of lactic acid with n-butanol may be performed to synthesize n-butyl lactate or to recover lactic acid from its aqueous solution. In the present work, the reaction is performed in the presence of cation-exchange resins as a catalyst. Kinetic parameters like activation energy and the rate constants are estimated using the pseudohomogeneous model. The applicability of Reactive Distillation for this reaction is evaluated through experiments using batch and continuous Reactive Distillation techniques. An equilibrium stage model is formulated, and simulation results are compared with the experimental results. Further, the effects of operating parameters like feed mole ratio, catalyst loading, and boilup rate are evaluated on the conversion of lactic acid in batch Reactive Distillation. Experimental results of continuous Reactive Distillation are compared with the simulation results observed using the Aspen plus process simulator. Effects of operating variables were studied with the help of the e...
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Recovery of lactic acid by batch Reactive Distillation
Journal of Chemical Technology & Biotechnology, 2006Co-Authors: Rakesh Kumar, Sanjay M. Mahajani, Hemant Nanavati, Santosh B. NoronhaAbstract:Lactic acid, being virtually a non-boiling compound, is difficult to separate from its aqueous solution by conventional methods such as Distillation. It is necessary to convert it to the relatively volatile ester and the separation of the ester, followed by hydrolysis, is recommended as an appropriate method of recovery. In the present work, we explore and investigate a novel Reactive Distillation strategy to perform esterification, Distillation and hydrolysis in a single unit. The experiments were performed in a batch Reactive Distillation set-up and the results have been explained with the help of an appropriate model. An unsteady state mathematical model based on an equilibrium stage concept was developed for batch Reactive Distillation. A pseudo-homogeneous model was used for the determination of reaction kinetics. The effect of operating parameters such as feed concentration, mole ratio, catalyst loading, boil-up rate, etc. on the recovery of lactic acid was studied with the help of simulation and experimental results. The feasibility issue of Reactive Distillation has been discussed based on the results obtained. Copyright © 2006 Society of Chemical Industry
William L Luyben - One of the best experts on this subject based on the ideXlab platform.
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Reactive Distillation design and control
2008Co-Authors: William L LuybenAbstract:Chapter1: Introduction 1.1 History 1.2 Basics of Reactive Distillation 1.3 Neat Operation versus Excess Reactant 1.4 Limitations 1.5 Scope 1.6 Computational Methods 1.7 References PART 1: STEADY-STATE DESIGN OF IDEAL QUATERNARY SYSTEM Chapter 2: Parameter Effects 2.1 Effect of Holdup on Reactive Trays 2.2 Effect of Number of Reactive Trays 2.3 Effect of Pressure 2.4 Effect of Chemical Equilibrium Constant 2.5 Effect of Relative Volatilities 2.6 Effect of Number of Stripping and Rectifying Trays 2.7 Effect of Reactant Feed Location 2.8 Conclusion Chapter 3: Economic Comparison of Reactive Distillation with a Conventional Process 3.1 Conventional Multi-Unit Process 3.2 Reactive Distillation Design 3.3 Results for Different Chemical Equilibrium Constants 3.4 Results for Temperature-Dependent Relative Volatilities 3.5 Conclusion Chapter 4: Neat Operation versus Using Excess Reactant 4.1 Introduction 4.2 Neat Reactive Column 4.3 Two-Column System with Excess B 4.4 Two-Column System with 20% Excess A 4.5 Economic Comparison 4.6 Conclusion PART 2: STEADY-STATE DESIGN OF OTHER IDEAL SYSTEMS Chapter 5: Ternary Reactive Distillation Systems 5.1 Ternary System without Inerts 5.2 Ternary System with Inerts 5.3 Conclusion Chapter 6: Ternary Decomposition Reaction 6.1 Intermediate Boiling Reactant 6.2 Heavy Key Reactant with Two Column Configuration 6.3 Heavy Key Reactant with One Column Configuration 6.4 Conclusion PART 3: STEADY-STATE DESIGN OF REAL CHEMICAL SYSTEMS Chapter 7: Steady-State Design for Acetic Acid Esterification 7.1 Reaction Kinetics and Phase Equilibrium 7.2 Process Flowsheets 7.3 Steady-State Design 7.4 Process Characteristics 7.5 Discussion 7.6 Conclusion Chapter 8: Design of TAME Reactive Distillation Systems 8.1 Chemical Kinetics and Phase Equilibrium 8.2 Component Balances 8.3 Effect of Parameters on Reactive Column 8.4 Pressure-Swing Methanol Separation Section 8.5 Extractive Distillation Methanol Separation Section 8.6 Economic Comparison 8.7 Conclusion Chapter 9: Design of MTBE and ETBE Reactive Distillation Columns 9.1 MTBE Process 9.2 ETBE Process 9.3 Conclusion PART 4: CONTROL OF IDEAL SYSTEMS Chapter 10: Control of Quaternary Reactive Distillation Columns 10.1 Introduction 10.2 Steady-State Design 10.3 Control Structures 10.4 Selection of Control Tray Location 10.5 Closedloop Performance 10.6 Using More Reactive Trays 10.7 Increasing Holdup on Reactive Trays 10.8 Rangeability 10.9 Conclusion Chapter 11: Control of Excess-Reactant System 11.1 Control Degrees of Freedom 11.2 Single Reactive Column Control Structures 11.3 Control of Two-Column System 11.4 Conclusion Chapter 12: Control of Ternary Reactive Distillation Columns 12.1 Ternary System without Inerts 12.2 Ternary System with Inerts 12.3 Ternary A B+C System: Intermediate Boiling Reactant 12.4 Ternary A B+C System: Heavy Reactant with Two-Column Configuration 12.5 Ternary A B+C System: Heavy Reactant with Single Column PART 5: CONTROL OF REAL SYSTEMS Chapter 13: Control of MeAc/ EtAc/IPAc/BuAc/AmAc Systems 13.1 Process Characteristic 13.2 Control Structure Design 13.3 Extension to Composition Control 13.4 Conclusion Chapter 14: Control of TAME Plantwide Process 14.1 Process Studied 14.2 Control Structure 14.3 Results 14.4 Conclusion Chapter 15 Control of MTBE and ETBE Reactive Distillation Columns 15.1 MTBE Control 15.2 ETBE Control PART 6: HYBRID AND NON-CONVENTIONAL SYSTEMS Chapter 16: Design and Control of Column/Side- Reactor Systems 16.1 Introduction 16.2 Design for Quaternary Ideal System 16.3 Control of Quaternary Ideal System 16.4 Design of Column/Side-Reactor Process for Ethyl Acetate System 16.5 Control of Column/Side-Reactor Process for Ethyl Acetate System 16.6 Conclusion Chapter 17: Effect of Boiling Point Rankings on the Design of Reactive Distillation 17.1 Process and Classification 17.2 Process Configurations 17.3 Relaxation and Convergence 17.4 Results and Discussion 17.5 Conclusion Chapter 18: Effects of Feed Tray Locations on the Design and Control of Reactive Distillation 18.1 Process Characteristics 18.2 Effects of Relative Volatilities 18.3 Effects of Reaction Kinetics 18.4 Operation and Control 18.5 Conclusion APPENDIX A1. Reference A2. Catalog of Types of Real Reactive Distillation Systems
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plantwide control for tame production using Reactive Distillation
Aiche Journal, 2004Co-Authors: Muhammad A Alarfaj, William L LuybenAbstract:The synthesis and control of a plantwide flowsheet to produce tert-amyl methyl ether (TAME) is reported. The flowsheet consists of a plug-flow reactor, one Reactive Distillation column, and two conventional Distillation columns. The two conventional columns are needed for the recovery of excess methanol and the inert C5s. The columns are operated at different pressures to overcome separation limitations resulting from the presence of azeotropes. The Reactive Distillation is run with an excess of methanol because it is needed for both the reaction and the azeotropic vapor liquid equilibrium (VLE) requirements in the column. The Reactive Distillation column is the critical unit in this flowsheet that needs to be carefully controlled. An effective control structure is one in which a temperature in the stripping section and a methanol composition in the Reactive zone are controlled. This control scheme is similar to that applied to other Reactive Distillation systems of the same type (that is, ETBE, MTBE). Because there is no reaction in the other two columns, they are effectively controlled by simple temperature controllers. The fresh feed of methanol must be manipulated to maintain the overall balance of methanol in the flowsheet. The proposed control structure is able to handle disturbances in feed rate and composition up to ±20%.© 2004 American Institute of Chemical Engineers AIChE J, 50: 1462–1473, 2004
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comparison of alternative control structures for an ideal two product Reactive Distillation column
Industrial & Engineering Chemistry Research, 2000Co-Authors: Muhammad A Alarfaj, William L LuybenAbstract:Although steady-state design and open-loop dynamics of Reactive Distillation columns have been explored in many papers, very few papers have dealt with closed-loop control. Most of these control papers consider Reactive Distillation columns in which there is only one product, and an excess of one of the reactants is sometimes assumed. This paper explores the closed-loop control of a Reactive Distillation column in which two products are produced in a single column and stoichiometric amounts of fresh feeds are desired. The reversible reaction is A + B ⇌ C + B. The relative volatilities are favorable for Reactive Distillation; i.e., the reactants are intermediate boilers between the light product C and the heavy product D. Simple ideal physical properties, kinetics, and vapor−liquid equilibrium are assumed so that the basic control issues of Reactive Distillation can be explored without being clouded by complexities of a specific chemical system. Six alternative control structures are evaluated via rigorous...
Kejin Huang - One of the best experts on this subject based on the ideXlab platform.
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Thermally Coupled Reactive Distillation System for the Separations of Cyclohexene/Cyclohexane Mixtures
Industrial & Engineering Chemistry Research, 2015Co-Authors: Li Shi, Haisheng Chen, Yang Yuan, Shaofeng Wang, Kejin HuangAbstract:Because of the very close boiling points of cyclohexene and cyclohexane, their separation is extremely difficult with conventional Distillation systems and Reactive separation with water as Reactive entrainer offers great economic incentives. In the current work, the synthesis and design of a flow-sheet with two Reactive Distillation columns (i.e., the hydration and dehydration Reactive Distillation columns) in series (FSTRDC) is first conducted subject to the minimization of total annual cost (TAC), and this leads to a process design with an excessive use of water. Although the process design facilitates the hydration of cyclohexene into cyclohexanol, it gives rise to a serious remixing effect in the hydration Reactive Distillation column and poses an unfavorable effect to the decomposition of cyclohexanol into cyclohexene and water in the dehydration Reactive Distillation column. For the suppression of these deficiencies, the hydration Reactive Distillation column was then modified to be heated directly...
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Dynamics and control of totally refluxed Reactive Distillation columns
Journal of Process Control, 2012Co-Authors: Kejin Huang, Haisheng Chen, Liang Zhang, San-jang WangAbstract:Abstract According to the mechanism of the reaction operation involved, Reactive Distillation columns are often designed to work in a totally refluxed operation mode. The totally refluxed operation mode makes the reflux drum interact solely with the reaction operation involved and retards considerably the dynamics of the latter. The resultant great difference in process dynamics between the reaction operation and the separation operation involved leads frequently to under-damped responses with the degree of under-dampness closely dependent on the inventory control of the reflux drum. With the tight inventory control of the reflux drum, the degree of under-dampness can be suppressed and this presents a favorable effect to process dynamics and controllability of the totally refluxed Reactive Distillation columns. Two hypothetical ideal Reactive Distillation columns with and without a side reaction, respectively, and a high-purity ethylene glycol Reactive Distillation column are employed to examine the unique dynamics and controllability of the totally refluxed Reactive Distillation columns. The results obtained are in good accordance with the above interpretation. The current work reveals the general behaviors of the totally refluxed Reactive Distillation columns and can be particularly useful in control system synthesis and design.
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Design and Analysis of Internally Heat-Integrated Reactive Distillation Processes
Industrial & Engineering Chemistry Research, 2012Co-Authors: Yang Jiao, San-jang Wang, Kejin Huang, Haisheng Chen, Wei LiuAbstract:Process intensification is aimed at integrating different processes in design to reduce utility consumption and capital investment, as well as at achieving environmental and safety benefits. Internally heat-integrated Distillation and Reactive Distillation are representative examples of such design technology. In this study, the performance of internally heat-integrated Reactive Distillation, a novel technology combining both internally heat-integrated Distillation and Reactive Distillation, is investigated for three ideal Reactive Distillation processes with a reaction zone located at top, middle, and bottom, respectively, of a Reactive Distillation column. The influences of reaction thermal effect (i.e., exothermic or endothermic reaction), relative volatilities between components, and chemical equilibrium constants on total annualized cost (TAC) are examined. Simulation results demonstrate that the internally heat-integrated Reactive Distillation can provide better economic benefit than conventional re...
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Reactive Distillation design with considerations of heats of reaction
AIChE Journal, 2006Co-Authors: Kejin Huang, Masaru Nakaiwa, San‐jang Wang, Atsushi TsutsumiAbstract:Although Reactive Distillation columns allow direct utilization of heat of reaction to separation operation, the effectiveness of internal heat integration appears generally to be unsatisfactory and their thermodynamic efficiency could quite often be improved substantially through seeking further internal heat integration between the reaction and separation operations. Prudent arrangement of Reactive section, effective determination of feed location, and deliberate distribution of catalyst constitute the three methods that can complement internal heat integration within a Reactive Distillation column. The Reactive section is suggested to superimpose properly onto the stripping section for exothermic reactions and onto the rectifying section for endothermic reactions. Feed location and distribution of catalyst should be determined so that the effect of internal heat integration can be maximized to its fullest extent. A sequential procedure is proposed to determine an appropriate process configuration for internal heat integration within a Reactive Distillation column. Five Reactive Distillation systems, involving not only equilibrium-limited but also kinetically controlled reactions, are used to evaluate the design philosophy proposed. It has been found that a substantial improvement in system performance can be achieved even for some reaction systems with side reactions and/or unfavorable thermodynamic properties. Seeking further internal heat integration has been demonstrated to be an effective method for refining process design of a Reactive Distillation column involving reactions with highly thermal effect. These conclusions are of great significance and can provide process designers with additional latitude to elaborate their process designs. © 2006 American Institute of Chemical Engineers AIChE J, 2006
George Buzad - One of the best experts on this subject based on the ideXlab platform.
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New tools for the design of kinetically controlled Reactive Distillation columns
Computers & Chemical Engineering, 1994Co-Authors: Michael F. Doherty, George BuzadAbstract:Abstract Reactive Distillation is an emerging technology that has great potential as a process alternative for carrying out liquid phase chemical reactions. Systematic design methods for Reactive Distillation systems have only recently begun to appear, and so far these have been restricted to systems at chemical equilibrium. It is not always economical, however, to operate Reactive Distillation columns close to reaction equilibrium conditions. In this paper we present a design procedure for kinetically controlled Reactive Distillation columns, and demonstrate the concepts for reactions of the type 2C ⇔ A + B. We show that the amount of liquid holdup per stage has a significant effect on the design, and that there is a sharp minimum in the total column holdup, at fixed product compositions, as the liquid holdup on each stage is varied.
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Reactive Distillation by design
Chemical Engineering Research & Design, 1992Co-Authors: Michael F. Doherty, George BuzadAbstract:During the last decade there has been a rapid upturn in interest in Reactive Distillation. The chemical process industry recognizes the favourable economics of carrying out reaction simultaneously with Distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for Reactive Distillation systems have only recently begun to emerge. We survey the available design techniques and point out opportunities for research
Michael F. Doherty - One of the best experts on this subject based on the ideXlab platform.
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Green Chemical Engineering Aspects of Reactive Distillation
Environmental science & technology, 2003Co-Authors: Michael F. Malone, Robert S. Huss, Michael F. DohertyAbstract:Reactive or catalytic Distillation technology combines chemical synthesis steps with separations by Distillation. This combination can lead to intensified, high-efficiency process systems with significant green engineering attributes. New applications and understanding have prompted growth in the use of Reactive Distillation for a variety of chemical syntheses, especially esterifications and etherifications involving oxygenated hydrocarbons. We describe several applications and the potential and tradeoffs for Reactive Distillation technology in the context of green engineering principles.
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Selectivity Targets for Batch Reactive Distillation
Industrial & Engineering Chemistry Research, 2000Co-Authors: Sagar B. Gadewar, And Michael F. Malone, Michael F. DohertyAbstract:Reactive Distillation has proved to be an important process alternative to the conventional reactor−separator configuration. Advantages of Reactive Distillation and flexibility of a batch process can be combined in batch Reactive Distillation. We present a simple method to estimate the advantage of using batch Reactive Distillation over conventional technology. For the examples studied, we determine yield and selectivity targets for a batch Reactive Distillation device. This method also determines the effect of operating parameters on yield and selectivity. We show that the advantage of using batch Reactive Distillation equipment is more significant for systems with fast side reactions. Comparison of these estimates with those for conventional reactors is useful for quick screening of process alternatives during process synthesis.
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New tools for the design of kinetically controlled Reactive Distillation columns
Computers & Chemical Engineering, 1994Co-Authors: Michael F. Doherty, George BuzadAbstract:Abstract Reactive Distillation is an emerging technology that has great potential as a process alternative for carrying out liquid phase chemical reactions. Systematic design methods for Reactive Distillation systems have only recently begun to appear, and so far these have been restricted to systems at chemical equilibrium. It is not always economical, however, to operate Reactive Distillation columns close to reaction equilibrium conditions. In this paper we present a design procedure for kinetically controlled Reactive Distillation columns, and demonstrate the concepts for reactions of the type 2C ⇔ A + B. We show that the amount of liquid holdup per stage has a significant effect on the design, and that there is a sharp minimum in the total column holdup, at fixed product compositions, as the liquid holdup on each stage is varied.
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Reactive Distillation by design
Chemical Engineering Research & Design, 1992Co-Authors: Michael F. Doherty, George BuzadAbstract:During the last decade there has been a rapid upturn in interest in Reactive Distillation. The chemical process industry recognizes the favourable economics of carrying out reaction simultaneously with Distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for Reactive Distillation systems have only recently begun to emerge. We survey the available design techniques and point out opportunities for research
