Heat pump assisted extractive distillation sequences with intermediate-boiling entrainer

Abstract

Currently, no research has focused on improving the economic efficiency and environmental sustainability of the classic extractive distillation (CED) process through using both vapor recompression heat pump (VRHP) and intermediate-boiling entrainer. In this paper, both VRHP configuration and intermediate-boiling entrainer benzene are introduced to improve economic efficiency and environmental sustainability of the direct CED (DCED) and indirect CED (IECD) sequences for separating the acetone/n-heptane azeotrope. The DCED and ICED are optimized by sequential iterative procedure, aiming at the minimum total annual costs (TAC). Furthermore, six independent VRHP-DCED and six independent VRHP-ICED sequences are designed and optimized to minimize steam and electricity consumption. The results illustrate that the ICED sequence can outperform the DCED sequence, while a part of the VRHP-CED sequences demonstrate the advantages compared to the ICED sequence in terms of economic, energy and environmental performance. The comparison with the ICED sequence shows that the VRHP-DCED (V) sequences with the minimum steam consumption can cause a decrease by 83.38%, while the VRHP-ICED (IV′) sequences with the minimum TAC and gas emissions can cause a reduction by 8.24% and 26.87% compared with the ICED sequence, respectively.