Multi-objective optimization of sustainable extractive dividing-wall column process for separating methanol and trimethoxysilane azeotrope mixture

Abstract

The design and optimization of distillation process for separating azeotropes has attracted extensive attentions in decades. Currently, due to the high emphasis on environmental and social effect, it is necessary to incorporate relevant criteria into the objective function in addition to the economic indicators for approaching a more sustainable process. This paper aims to improve the process for separating the azeotropic mixture of methanol and trimethoxysilane via multi-objective optimization based on NSGA-II. Firstly, the performance of three processes, i.e., pressure-swing distillation, extractive distillation, and extractive dividing wall column (EDWC) distillation, is optimized and compared by using total annual cost (TAC) as the objective function, demonstrating that the EDWC distillation process is the preferred process. Subsequently, a heat pump assisted EDWC process (HP-EDWC) is proposed, and the multi-objective optimization is carried out based on NSGA-II algorithm with three criteria including TAC, carbon emission, and the thermodynamic efficiency, to obtain a set of Pareto solutions, which are then evaluated by using a multi-criteria decision-making method of TOPSIS to give the optimal solution. As a result, the values of TAC, carbon emission, and thermodynamic efficiency of the optimal HP-EDWC process are 90.30×104 $/year, 501.07 kg/h, and 26.02%, respectively.