Comparison of extractive distillation separation sequences for acetonitrile/methanol/benzene multi‐azeotropic mixtures

Abstract

Background The extractive distillation‐based separation of a multi‐azeotropic mixture has several optional solvents and schemes. The screen of a suitable solvent was performed and diverse extractive distillation sequences were compared for separating the specified mixture of acetonitrile/methanol/benzene. Result As a solvent breaking all binary azeotropes, chlorobenzene was selected over aniline on the basis vapor–liquid equilibrium diagrams and infinite dilution factors. Four separation sequences were optimized by the sequential iterative procedure on the basis of minimal total annual cost (TAC), and CO2 emissions were calculated. Among four sequences, sequence III, composed of two extractive distillation columns and one solvent recovery column, is the best scheme from environmental and economic viewpoints. Simple partial heat integration was further implemented and can save 20.08% and 8.86% in terms of energy cost and TAC. Conclusion The results demonstrate that the separation of acetonitrile/methanol/benzene is fully achievable using common extractive distillation with chlorobenzene as solvent. Moreover, there is a trade‐off between heat transfer in the reboiler‐condenser and corresponding energy consumption variations due to pressure changes when considering heat integration. © 2018 Society of Chemical Industry

Separation of a ternary mixture with multiple azeotropes via pressure‐swing distillation

“…However, the mixture must be handled properly in order to avoid waste of resources and environmental pollution. Conventional distillation is unable to effectively separate this system due to the presence of three binary azeotropes, and thus some special separation methods must be considered . Recently, a few studies have been reported for the separation of the THF–ethanol–water system via extractive distillation and PSD.…”

“…Conventional distillation is unable to effectively separate this system due to the presence of three binary azeotropes, and thus some special separation methods must be considered. [16][17][18] Recently, a few studies have been reported for the separation of the THF-ethanol-water system via extractive distillation and PSD. Zhao et al 19,20 investigated the steady state design of conventional and thermally coupled extractive distillation configurations with various extracting agents.…”

Optimization of Solvent and Extractive Distillation Sequence Considering Its Integration with Reactor

“…Zhang et al proposed a method for identifying the optimal solvent on the basis of isovolatility curves [3]. Based on vaporliquid equilibrium diagrams and infinite dilution factors, Wang et al selected the feasible solvent to separate the specified mixture and targeted the optimal distillation sequence with minimum TAC [4]. In view of controllability and economy, Wang et al simulated two possible extractive distillation sequences for separating toluene-methanol-water ternary azeotropic mixture to identify suitable flowrate of solvent [5].…”

Isobaric vapor–liquid equilibrium of tert‐butanol + water + ionic liquids at atmospheric pressure

“…The addition of the solvent is to enhance the relative volatility of azeotropic mixtures. [5][6][7] An appropriate solvent possesses not only high solubility but also high selectivity to the separated mixture. Usually, for extractive distillation, there are three kinds of solvent, namely organic solvent, 8 inorganic salt 9 or mixtures of inorganic salt and organic solvent.…”

“…In the circumstances, extractive distillation which is usually used to separate azeotropic mixtures or close‐boiling mixtures was adopted by adding an appropriate solvent. The addition of the solvent is to enhance the relative volatility of azeotropic mixtures 5–7 . An appropriate solvent possesses not only high solubility but also high selectivity to the separated mixture.…”