Unfavorable process intensification of double column reactive extractive distillation system

Abstract

This study evaluated the energy saving potential of process intensified double column reactive extractive distillation (DC-RED) through three case studies. The results showed that process intensified technologies, thermally coupled reactive extractive distillation (TC-RED) and dividing wall reactive extractive distillation (DW-RED), did not yield any energy savings compared to conventional DC-RED. Contrary to the expectation, the elimination of the remixing effect in the process intensified DC-RED did not lead to any energy savings. Further analysis revealed that the remixing effect was not significant enough to achieve energy savings through process intensification, and the strong reaction exotherm in DC-RED reduced the potential for energy saving. Additionally, the higher interconnection flowrate in TC-RED and DW-RED resulted in higher energy consumption due to the increased boil-up ratio. Moreover, the lower feed temperature to the solvent recovery column (SRC) led to less energy efficiency and larger reboiler duty. An alternative energy saving scheme was proposed by adding a heat exchanger (HEX). The addition of HEX led to energy savings of 37.23 % in Acetonitrile (ACN)/Isopropanol (IPA)/Water separation, 45.62 % in Ethyl Acetate (EA)/Ethanol (EtOH)/Water separation, and 39.21 % in IPA/EA/Water separation.