A new hybrid reactive-extractive distillation configuration for ternary azeotropic separation with intensification opportunity

Abstract

The concept of reactive-extractive distillation (RED) is not new and has gained significant attention as an innovative approach for separating azeotropic mixtures. Presently, there have been at least 18 studies on RED, exploring variations such as triple column RED (TCRED), double column RED (DCRED), and their intensified configurations like dividing-wall DCRED (DW-DCRED) or side-stream DCRED (SS-DCRED). However, a major drawback observed in all existing intensified RED studies is the inability to achieve energy savings, which contrasts with the outcomes of most conventional distillation system studies. To address this, we propose a new alternative configuration called extractive-reactive distillation (ED-RD) by rearranging the column sequence in DCRED. The ED-RD configuration achieves a substantial 7 % reduction in the total annual cost (TAC) compared to DCRED, primarily due to a reduced number of stages and the utilization of relatively cheaper low-pressure steam in the extractive distillation column (EDC). Furthermore, the intensified thermally coupled ED-RD (TC-ED-RD) configuration demonstrates superior performance, achieving an impressive 21 % reduction in TAC compared to the proposed ED-RD configuration, mainly driven by a significant decrease in total reboiler energy consumption. Overall, the TC-ED-RD configuration excels with a remarkable 28 % reduction in total reboiler energy consumption and a 27 % decrease in TAC compared to DCRED. This reflects the potential of incorporating process intensification techniques to the proposed configuration to achieve substantial energy and cost savings, in contrast to the limitations observed in the conventional RED systems.