Conceptual design of the triple-column extractive distillation processes with single entrainer and double entrainer for separating the N-hexane/acetone/chloroform ternary multi-azeotropic mixture

Currently, there are very limited efforts on investigating triple-column extractive distillation process with single entrainer (S-TCED) for separating ternary multi-azeotropic mixture with special phase behavior. Therefore, two counter-intuitive methods, including conventional S-TCED and double side-stream S-TCED, are proposed for separating the N-hexane/acetone/chloroform mixture containing four azeotropes, in comparison with the correspondingly intuitive method of triple-column extractive distillation process with double entrainer (D-TCED). First, dimethyl sulfoxide is selected to break azeotropes and increase the relative volatility through vapor liquid equilibrium analysis and maximum selectivity calculation. Subsequently, the conceptual design of extractive distillation flowsheets is performed via thermodynamic insights, especially for two S-TCED configurations. Genetic algorithm is adopted to optimize separation schemes with the minimal total annual cost (TAC). The optimization results show that two S-TCED flowsheets can perform the separation of the ternary multi-azeotropic mixture, and even cause the slight reduction in TAC compared to their corresponding D-TCED configurations, respectively. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study compares the separation methods of triple-column extractive distillation process with double entrainer and single entrainer for ternary multi-azeotropic mixtures with special phase behavior. Through thermodynamic analysis and genetic algorithm optimization, it is demonstrated that the S-TCED process with single entrainer can effectively perform the separation.