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Michael F. Doherty - One of the best experts on this subject based on the ideXlab platform.
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prediction of heterogeneous reactive Azeotropes in esterification systems
Chemical Engineering Science, 2000Co-Authors: Matthew J Okasinski, Michael F. DohertyAbstract:Abstract This paper develops the conditions for heterogeneous reactive azeotropy and expands the method described in Okasinski and Doherty (A. I. Ch. E J. 43 (1997) 2227–2238) to cover heterogeneous reactive mixtures, enabling the existence and location of both homogeneous and heterogeneous reactive Azeotropes to be determined. Esterification reactions of acetic acid with isopropanol, n -propanol, n -butanol, and n -pentyl alcohol are examined. The results for the n -propanol system, portrayed on a bifurcation diagram, indicate the presence of a heterogeneous minimum-boiling quaternary reactive azeotrope at the value of the reaction equilibrium constant reported in the literature. A heterogeneous reactive azeotrope has not been theoretically predicted before for any mixture. This prediction provides an opportunity for new experiments on heterogeneous, reacting mixtures to determine the validity of the prediction.
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Computing all homogeneous and heterogeneous Azeotropes in multicomponent mixtures
Industrial & Engineering Chemistry Research, 1999Co-Authors: Stanislaw K Wasylkiewicz, Michael F. Doherty, Michael F. MaloneAbstract:A homotopy method for computing Azeotropes in homogeneous multicomponent mixtures, developed by Fidkowski et al.,1 has been generalized to include heterogeneous liquids. The method together with an arc length continuation and a rigorous stability analysis and calculation of liquid−liquid equilibrium in multicomponent mixtures, developed by Wasylkiewicz et al.,2 gives an efficient and robust scheme for finding all homogeneous as well as heterogeneous Azeotropes predicted by a thermodynamic model. A new, more general homotopy function has been proposed which reduces to the form proposed by Fidkowski et al.1 for homogeneous liquid mixtures. Unlike the homogeneous case, turning points can often be found on solution branches leading to the heterogeneous Azeotropes. A few examples for heterogeneous systems are shown and compared with results obtained using the homogeneous models.
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Structure of Distillation Regions for Multicomponent Azeotropic Mixtures
Aiche Journal, 1998Co-Authors: Raymond E. Rooks, Michael F. Doherty, Vivek Julka, Michael F. MaloneAbstract:Geometric methods for the conceptual design of nonideal and azeotropic distillation systems have focused primarily on three- and four-component mixtures. A generalization of geometric methods that does not rely on visualization and gives a completely equation-based approach to determine the structure of distillation regions for homogeneous mixtures is described. This method is useful for mixtures with a large number of components, provided a vapor–liquid equilibrium model is available. The approach is applied to assess feasibility and alternative separations in several examples, including a five-component mixture with nine Azeotropes and a six-component mixture with seven Azeotropes. These methods can be used to rapidly generate process alternatives, and the examples demonstrate that there can be a surprising number of these alternatives for the distillation of azeotropic mixtures.
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thermodynamic behavior of reactive Azeotropes
Aiche Journal, 1997Co-Authors: Matthew J Okasinski, Michael F. DohertyAbstract:During process design of reactive distillation systems, there is often uncertainty in the value of the reaction equilibrium constant (Keq), whether it is determined experimentally or calculated from thermochemical data. The effect of the reaction equilibrium constant on the existence and location of reactive Azeotropes (constant boiling reactive mixtures) is explored for chemical equilibrium systems with a single chemical reaction. With a known set of starting points, arc-length continuation was used to track solutions of the equations for reactive azeotropy as a function of the reaction equilibrium constant. The results, portrayed in bifurcation diagrams, reveal that Azeotropes may appear or disappear as the equilibrium constant is varied. Results for the esterification of acetic acid with ethanol indicate three distinct regions of phase behavior. The first regime (Keq < 0.449) contains a quaternary saddle reactive azeotrope. At intermediate values of the reaction equilibrium constant (0.449 < Keq <12.5), there are no reactive Azeotropes in the system. In the third regime (Keq < 12.5), a minimum-boiling quaternary reactive azeotrope appears. In addition, for three reported literature values of the reaction equilibrium constant, each one lies in a different regime. Other examples also illustrate the broad taxonomy of reactive azeotropic systems.
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necessary and sufficient conditions for reactive Azeotropes in multireaction mixtures
Aiche Journal, 1995Co-Authors: Sophie Ung, Michael F. DohertyAbstract:Necessary and sufficient conditions for azeotropy in reactive mixtures derived show that in the space of transformed compositions, they take the same functional form as the conditions for azeotropy in nonreactive mixtures. In general, reactive Azeotropes do not correspond to points of equal mole fraction (or mass fraction) across the coexisting equilibrium phases. The relationship between stationary points in the equilibrium temperature or pressure surface and reactive Azeotropes is also considered, as well as their relevance to the Gibbs-Konovalov theorems.
Yinglong Wang - One of the best experts on this subject based on the ideXlab platform.
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thermal coupled extractive distillation sequences with three entrainers for the separation of azeotrope isopropyl alcohol diisopropyl ether
Journal of Chemical Technology & Biotechnology, 2020Co-Authors: Yi Zhang, Jun Gao, Zhishan Zhang, Lianzheng Zhang, Yinglong WangAbstract:BACKGROUND: During the synthesis of isopropyl alcohol (IPA) by hydration of propylene, diisopropyl ether (DIPE) is usually produced as a by‐product. Because IPA and DIPE can form a binary homogeneous azeotrope with the minimum boiling temperature at atmospheric pressure, it is difficult to separate the binary mixture by simple distillation. RESULT: For separating the azeotrope IPA + DIPE, side‐stream extractive distillation column (SSED) and extractive dividing wall column (EDWC) processes with three entrainers [2‐methoxyethanol (2‐MEA), 2‐ethoxyethanol and propylene glycol ethyl ether (PGEE)] were simulated and optimized based on the minimal total annual cost (TAC). Moreover, CO₂ emissions of the six sequences were calculated and the impact on the environment evaluated. CONCLUSIONS: The sequence of SSED with PGEE as entrainer can reduce TAC by ≤34.48%, but EDWC with PGEE can offer TAC reduction of ≤52.46%. The results demonstrate that the EDWC sequence with PGEE as entrainer is favourable for separating the binary azeotrope IPA + DIPE. © 2020 Society of Chemical Industry
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vapour liquid equilibrium measurements and extractive distillation process design for separation of azeotropic mixture dimethyl carbonate ethanol
The Journal of Chemical Thermodynamics, 2019Co-Authors: Kai Liu, Jun Gao, Zhaojie Wang, Yi Zhang, Yinglong WangAbstract:Abstract Dimethyl carbonate and ethanol can form an azeotrope with the minimum boiling point. To separate the azeotrope (dimethyl carbonate + ethanol) by extractive distillation, p-xylene, butyl propionate, and isobutyl acetate were chosen as entrainers, and the isobaric vapour-liquid equilibrium (VLE) data for the binary systems of (dimethyl carbonate + p-xylene), (dimethyl carbonate + butyl propionate), (dimethyl carbonate + isobutyl acetate) and (ethanol + isobutyl acetate) were measured at 101.3 kPa using a modified Rose type recirculating still. The thermodynamic consistency of the VLE experimental data for the four binary mixtures was tested by the Herington and van Ness methods. Furthermore, the measured VLE data were correlated by the NRTL, UNIQUAC and Wilson thermodynamic models and the binary interaction parameters of the three models were regressed. Based above, an extractive distillation process with the entrainer of p-xylene was proposed and simulated to separate the azeotrope (dimethyl carbonate + ethanol).
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qspr modeling of azeotropic temperatures and compositions for binary Azeotropes containing lower alcohols using a genetic function approximation
Chinese Journal of Chemical Engineering, 2019Co-Authors: Huixin Wang, Jun Gao, Xueli Geng, Zhaoyou Zhu, Yinglong WangAbstract:Abstract Binary Azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding Azeotropes is essential for effectively separating binary Azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results; however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship (QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary Azeotropes containing lower alcohols. The QSPR models for 64 binary Azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation (GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted. External tests of an additional 16 Azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the Azeotropes, and good predictive ability was obtained within acceptable prediction error levels.
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ternary liquid liquid equilibria for systems containing dimethyl carbonate or methyl acetate methanol 1 methylmidazole hydrogen sulfate at 298 15 k and 318 15 k
The Journal of Chemical Thermodynamics, 2018Co-Authors: Guilin Wen, Xueli Geng, Yinglong Wang, Wenting Bai, Jun GaoAbstract:Abstract The separation of methanol from its Azeotropes is very important for the production process of vinyl alcohol and dimethyl carbonate. This work describes the feasibility of separating (methanol + methyl acetate) and (methanol + dimethyl carbonate) Azeotropes by liquid-liquid extraction using ionic liquid as solvent. The ternary liquid-liquid equilibria (LLE) data for the systems of {methyl acetate + methanol + 1-methylmidazole hydrogen sulfate ([MIM]HSO4]}, {dimethyl carbonate + methanol + [MIM][HSO4]} were measured at 298.15 K and 318.15 K under atmospheric pressure. The separation factor and distribution coefficient were calculated from the experimental LLE results to evaluate the separation performance. The influence of temperature on the LLE was investigated and discussed. The experimental LLE data were satisfactorily correlated by NRTL and UNIQUAC models, the binary interaction parameters were obtained and the calculated LLE data were compared with the experimental results.
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measurement and correlation of isobaric vapor liquid equilibrium for binary systems of allyl alcohol with isobutyl acetate butyl acetate and butyl propionate at 101 3 kpa
Journal of Chemical & Engineering Data, 2018Co-Authors: Yangchen Gao, Jun Gao, Puyun Shi, Zhishan Zhang, Yinglong WangAbstract:For separation of the azeotrope of allyl alcohol and water, three extractive agents—isobutyl acetate, butyl acetate, and butyl propionate—were selected to extract allyl alcohol from the azeotrope. To recover the extractive agents by distillation, the isobaric vapor–liquid phase equilibrium (VLE) data for allyl alcohol + isobutyl acetate, allyl alcohol + butyl acetate, and allyl alcohol + butyl propionate were measured at 101.3 kPa. With the VLE data, there is no azeotrope formed in three systems. The consistency of the measured VLE data was validated by the Herington, infinite dilution, pure component consistency, and van Ness tests. Moreover, the Wilson, UNIQUAC, and NRTL models were used to fit the measured VLE data. All of the calculated results agreed with the VLE experimental data. Meanwhile, the parameters of the Wilson, UNIQUAC, and NRTL were regressed, which can be employed for the development and optimization of the separation process. Furthermore, the VLE data were predicted by the UNIFAC model ...
Vincent Gerbaud - One of the best experts on this subject based on the ideXlab platform.
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design and control of pressure swing distillation for separating ternary systems with three binary minimum Azeotropes
Aiche Journal, 2019Co-Authors: Ao Yang, Weifang Shen, Lichun Dong, Jie Li, Vincent GerbaudAbstract:The separation of ternary nonideal systems with multi‐azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi‐azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple‐column pressure‐swing distillation for separating ternary systems with three binary minimum Azeotropes. This procedure involves thermodynamic insights, a two‐step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple‐column pressure‐swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 106 in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur.
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Design and control of pressure‐swing distillation for separating ternary systems with three binary minimum Azeotropes
AIChE Journal, 2019Co-Authors: Ao Yang, Weifang Shen, Lichun Dong, Shun An Wei, Vincent GerbaudAbstract:The separation of ternary nonideal systems with multi‐azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi‐azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple‐column pressure‐swing distillation for separating ternary systems with three binary minimum Azeotropes. This procedure involves thermodynamic insights, a two‐step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple‐column pressure‐swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 106 in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur.
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A Novel Method for Detecting and Computing Univolatility Curves in Ternary Mixtures
Chemical Engineering Science, 2017Co-Authors: Nataliya Shcherbakova, Ivonne Rodriguez-donis, Jens Abildskov, Vincent GerbaudAbstract:Residue curve maps (RCMs) and univolatility curves are crucial tools for analysis and design of distillation processes. Even in the case of ternary mixtures, the topology of these maps is highly non-trivial, as shown by Serafimov’s and Zhvanetskii’s classifications. We propose a novel method allowing detection and computation of the existence of univolatility curves in homogeneous ternary mixtures independently of the presence of Azeotropes, which is particularly important in the case of zeotropic mixtures. The method is based on analysis of the geometry of the boiling temperature surface constrained by the univolatility or unidistribution condition. The introduced on the concepts of the generalized univolatility and unidistribution curves in the three dimensional composition – temperature state space that lead to a simple non iterative and efficient algorithm of computation of the univolatility curves. Two peculiar ternary systems, namely diethylamine – chloroform – methanol and hexane – benzene – hexafluorobenzene are used for illustration. When varying pressure, tangential azeotropy, bi-ternary azeotropy, saddle-node ternary azeotrope, and bi-binary azeotropy are found. In both examples, a distinctive crossing shape of the univolatility curve appears as a consequence of the existence of a common tangent point between the three dimensional univolatility hypersurface and the boiling temperature surface. Moreover, rare univolatility curves starting and ending on the same binary side are found.
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Systematic design of an extractive distillation for maximum-boiling Azeotropes with heavy entrainers
AIChE Journal, 2015Co-Authors: Weifeng Shen, Lichun Dong, Shun An Wei, Hassiba Benyounes, Xinqiang You, Vincent GerbaudAbstract:Extractive distillation is one of the most attractive approaches for separating azeotropic mixtures. Few contributions have been reported to design an extractive distillation for separating maximum-boiling Azeotropes and no systematic approaches for entrainer screening have been presented. A systematic approach to design of two-column extractive distillation for separating Azeotropes with heavy entrainers has been proposed. A thermodynamic feasibility analysis for Azeotropes with potential heavy entrainers was first conducted. Then, five important properties are selected for entrainer evaluation. Fuzzy logic and develop membership functions to calculate attribute values of selected properties have been used. An overall indicator for entrainer evaluation is proposed and a ranking list is generated. Finally, the top five entrainers from the ranking list have been selected and use process optimization techniques to further evaluate selected entrainers and generate an optimal design. The capability of the proposed method is illustrated using the separation of acetone–chloroform Azeotropes with five potential entrainers.
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thermodynamic insight on extractive distillation with entrainer forming new Azeotropes
2010Co-Authors: Ivonne Rodriguezdonis, Vincent Gerbaud, Xavier JouliaAbstract:This paper deals with the feasibility analysis of batch extractive distillation taking into account the effect of the univolatility lines ai,j = 1 and the shape of residue curves for ternary mixtures involving two binary Azeotropes. A general feasibility criterion previously established for ternary mixtures only including one azeotrope is now extended to Serafimov’s classification diagrams: 2.0-1, 2.0-2a, 2.0-2b and 2.0-2c. Application of the feasibility criterion hints at which component goes up or down using a rectifying or stripping column. Preliminary feasibility results are verified by computing the map of extractive liquid profiles using a simplified modelling. Examples including batch rectifier are also corroborated by rigorous simulation using ProSim Batch.
Jun Gao - One of the best experts on this subject based on the ideXlab platform.
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thermal coupled extractive distillation sequences with three entrainers for the separation of azeotrope isopropyl alcohol diisopropyl ether
Journal of Chemical Technology & Biotechnology, 2020Co-Authors: Yi Zhang, Jun Gao, Zhishan Zhang, Lianzheng Zhang, Yinglong WangAbstract:BACKGROUND: During the synthesis of isopropyl alcohol (IPA) by hydration of propylene, diisopropyl ether (DIPE) is usually produced as a by‐product. Because IPA and DIPE can form a binary homogeneous azeotrope with the minimum boiling temperature at atmospheric pressure, it is difficult to separate the binary mixture by simple distillation. RESULT: For separating the azeotrope IPA + DIPE, side‐stream extractive distillation column (SSED) and extractive dividing wall column (EDWC) processes with three entrainers [2‐methoxyethanol (2‐MEA), 2‐ethoxyethanol and propylene glycol ethyl ether (PGEE)] were simulated and optimized based on the minimal total annual cost (TAC). Moreover, CO₂ emissions of the six sequences were calculated and the impact on the environment evaluated. CONCLUSIONS: The sequence of SSED with PGEE as entrainer can reduce TAC by ≤34.48%, but EDWC with PGEE can offer TAC reduction of ≤52.46%. The results demonstrate that the EDWC sequence with PGEE as entrainer is favourable for separating the binary azeotrope IPA + DIPE. © 2020 Society of Chemical Industry
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vapour liquid equilibrium measurements and extractive distillation process design for separation of azeotropic mixture dimethyl carbonate ethanol
The Journal of Chemical Thermodynamics, 2019Co-Authors: Kai Liu, Jun Gao, Zhaojie Wang, Yi Zhang, Yinglong WangAbstract:Abstract Dimethyl carbonate and ethanol can form an azeotrope with the minimum boiling point. To separate the azeotrope (dimethyl carbonate + ethanol) by extractive distillation, p-xylene, butyl propionate, and isobutyl acetate were chosen as entrainers, and the isobaric vapour-liquid equilibrium (VLE) data for the binary systems of (dimethyl carbonate + p-xylene), (dimethyl carbonate + butyl propionate), (dimethyl carbonate + isobutyl acetate) and (ethanol + isobutyl acetate) were measured at 101.3 kPa using a modified Rose type recirculating still. The thermodynamic consistency of the VLE experimental data for the four binary mixtures was tested by the Herington and van Ness methods. Furthermore, the measured VLE data were correlated by the NRTL, UNIQUAC and Wilson thermodynamic models and the binary interaction parameters of the three models were regressed. Based above, an extractive distillation process with the entrainer of p-xylene was proposed and simulated to separate the azeotrope (dimethyl carbonate + ethanol).
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qspr modeling of azeotropic temperatures and compositions for binary Azeotropes containing lower alcohols using a genetic function approximation
Chinese Journal of Chemical Engineering, 2019Co-Authors: Huixin Wang, Jun Gao, Xueli Geng, Zhaoyou Zhu, Yinglong WangAbstract:Abstract Binary Azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding Azeotropes is essential for effectively separating binary Azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results; however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship (QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary Azeotropes containing lower alcohols. The QSPR models for 64 binary Azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation (GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted. External tests of an additional 16 Azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the Azeotropes, and good predictive ability was obtained within acceptable prediction error levels.
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ternary liquid liquid equilibria for systems containing dimethyl carbonate or methyl acetate methanol 1 methylmidazole hydrogen sulfate at 298 15 k and 318 15 k
The Journal of Chemical Thermodynamics, 2018Co-Authors: Guilin Wen, Xueli Geng, Yinglong Wang, Wenting Bai, Jun GaoAbstract:Abstract The separation of methanol from its Azeotropes is very important for the production process of vinyl alcohol and dimethyl carbonate. This work describes the feasibility of separating (methanol + methyl acetate) and (methanol + dimethyl carbonate) Azeotropes by liquid-liquid extraction using ionic liquid as solvent. The ternary liquid-liquid equilibria (LLE) data for the systems of {methyl acetate + methanol + 1-methylmidazole hydrogen sulfate ([MIM]HSO4]}, {dimethyl carbonate + methanol + [MIM][HSO4]} were measured at 298.15 K and 318.15 K under atmospheric pressure. The separation factor and distribution coefficient were calculated from the experimental LLE results to evaluate the separation performance. The influence of temperature on the LLE was investigated and discussed. The experimental LLE data were satisfactorily correlated by NRTL and UNIQUAC models, the binary interaction parameters were obtained and the calculated LLE data were compared with the experimental results.
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measurement and correlation of isobaric vapor liquid equilibrium for binary systems of allyl alcohol with isobutyl acetate butyl acetate and butyl propionate at 101 3 kpa
Journal of Chemical & Engineering Data, 2018Co-Authors: Yangchen Gao, Jun Gao, Puyun Shi, Zhishan Zhang, Yinglong WangAbstract:For separation of the azeotrope of allyl alcohol and water, three extractive agents—isobutyl acetate, butyl acetate, and butyl propionate—were selected to extract allyl alcohol from the azeotrope. To recover the extractive agents by distillation, the isobaric vapor–liquid phase equilibrium (VLE) data for allyl alcohol + isobutyl acetate, allyl alcohol + butyl acetate, and allyl alcohol + butyl propionate were measured at 101.3 kPa. With the VLE data, there is no azeotrope formed in three systems. The consistency of the measured VLE data was validated by the Herington, infinite dilution, pure component consistency, and van Ness tests. Moreover, the Wilson, UNIQUAC, and NRTL models were used to fit the measured VLE data. All of the calculated results agreed with the VLE experimental data. Meanwhile, the parameters of the Wilson, UNIQUAC, and NRTL were regressed, which can be employed for the development and optimization of the separation process. Furthermore, the VLE data were predicted by the UNIFAC model ...
William L Luyben - One of the best experts on this subject based on the ideXlab platform.
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control of a triple column pressure swing distillation process
Separation and Purification Technology, 2017Co-Authors: William L LuybenAbstract:Abstract The separation of the ternary mixture of acetonitrile, methanol and benzene into three high-purity products is complicated by the presence of three binary Azeotropes that divide the ternary diagram into three distinct regions. Fortunately the compositions of two of these Azeotropes change significantly with pressure. The economic optimum flowsheet has been developed in a recent paper in the literature that uses a process with three columns operating at different pressures. Three high-purity products are produced as bottoms streams from the three columns with the distillate of the third column recycled back to the first column. The plantwide dynamic controllability of this complex, non-ideal interacting process is studied in this paper. An effective control structure is developed that controls one temperature in each column. Pressure compensation in the low-pressure column improves load rejection of both throughput and feed composition disturbances. No on-line composition measurement is required.
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Pressure-Swing Distillation for Minimum- and Maximum-Boiling Homogeneous Azeotropes
Industrial & Engineering Chemistry Research, 2012Co-Authors: William L LuybenAbstract:Pressure-swing azeotropic distillation uses two columns operating at two different pressures to separate azeotropic mixtures by taking high-purity product streams from one end of the columns and recycling the streams from the other end with compositions near the two Azeotropes. This configuration can be economically used when changes in pressure significantly shift the composition of the azeotrope. The larger the shift, the smaller the required recycle flow rates, so the smaller the energy requirements in the two reboilers. Pressure-swing distillation can be applied to both minimum-boiling and maximum-boiling homogeneous azeotropic mixtures. With minimum-boiling systems, the distillate streams are recycled. With maximum-boiling systems, the bottoms streams are recycled. Intuition would lead us to expect that recycling distillate streams would be more energy intensive than recycling bottoms streams. A distillate recycle must be boiled up in the column. A bottoms recycle stream is not boiled up. Therefore, ...
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design and control of the butyl acetate process
Industrial & Engineering Chemistry Research, 2011Co-Authors: William L LuybenAbstract:Butyl acetate can be produced by the reaction of methyl acetate with butanol in a reversible, liquid-phase, mildly exothermic reaction. Methanol is the second product. The chemical equilibrium constant is less than unity, so the reactor effluent contains significant amounts of the reactants, which must be recovered for recycle back to the reactor. The volatilities are such that there are three distillation columns and two recycles. The nonideal vapor−liquid equilibrium results in two Azeotropes that must be considered. The first column C1 takes the two light components overhead (methyl acetate and methanol) and the two heavy components out of the bottom (butanol and butyl acetate). The C1 distillate is fed to a second column, which produces product methanol out of the bottom and a recycle stream of the methyl acetate/methanol azeotrope in the distillate. The C1 bottoms is fed to a third column, which produces product butyl acetate out of the bottom and a recycle stream of butanol in the distillate. Becaus...
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two stripper decanter flowsheet for methanol recovery in the tame reactive distillation process
Industrial & Engineering Chemistry Research, 2009Co-Authors: Ilung Chien, William L LuybenAbstract:The process to produce TAME via reactive distillation requires a methanol-recovery section because the presence of C5/methanol Azeotropes means that a significant amount of methanol is present in the distillate from the reactive column. The use of pressure-swing azeotropic distillation and extractive distillation were studied in a previous paper in which both the steady-state design and the plantwide control of the entire process were developed. This paper considers a third alternative flowsheet for the separation of the C5/methanol Azeotropes that takes advantage of the heterogeneity of the azeotrope. Two stripping columns and a decanter are used. The total annual cost of this flowsheet is a factor of 4 less than that of the pressure-swing system. The system is demonstrated to be easy to control by controlling a tray temperature in each stripping column.
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control of the maximum boiling acetone chloroform azeotropic distillation system
Industrial & Engineering Chemistry Research, 2008Co-Authors: William L LuybenAbstract:The literature contains a number of papers that study the control of azeotropic distillation systems. Both homogeneous and heterogeneous Azeotropes have been considered, but all of the systems considered in these control papers deal only with minimum-boiling Azeotropes. These Azeotropes are caused by molecular repulsion between different types of chemical components and are more common than systems in which molecular attractions occur that result in maximum-boiling Azeotropes. There appears to be no papers that study the control of this type of azeotropic system. This paper explores the design and control of the maximum-boiling azeotropic acetone/chloroform distillation system. The normal boiling points of the two pure components are 329.4 and 334.3 K, while the azeotropic boils at 337.6 K at 1 atm with a composition of 34.09 mol % acetone. A two-column extractive distillation process is used with dimethyl sulfoxide as the solvent. The two components are separated into 99.5 mol % pure products leaving in ...
