Optimization of the composition of mixed entrainer for economic extractive distillation process in view of the separation of tetrahydrofuran/ethanol/water ternary azeotrope

BACKGROUND: There are three binary azeotropes in the tetrahydrofuran/ethanol/water ternary system at atmospheric pressure. Ternary extractive distillation (ED) processes were studied to separate the ternary azeotropic mixture using two single component solvents and a mixed solvent as entrainer. RESULT: Based on the sequential iterative optimization procedure, the minimal total annual costs (TACs) of the ternary extractive distillation process using ethylene glycol (EG), dimethyl sulfoxide (DMSO), and the mixture of DMSO and EG as entrainer were obtained. Compared with two single component entrainers DMSO and EG, the TAC of the extractive distillation process with mixed entrainer (60 mol% DMSO + 40 mol% EG) decreases by 6.55% and 31.88%, respectively. Furthermore, the reboiler heat duties of two extractive distillation columns (EDCs) with mixed entrainer were compared with two single component entrainers. CONCLUSION: The results show that the optimal ED process using mixed entrainer performs better than that using single component entrainers from the perspective of economics. Moreover, there is a tradeoff between the reboiler heat duties of two EDCs, which can be adjusted by changing the entrainer performance in two EDCs. The use of mixed entrainer enhances the flexibility of the tradeoff because it only needs to change the composition of the mixed entrainer. (C) 2017 Society of Chemical Industry