Optimal Design, Proportional-Integral, and Model Predictive Control of Intensified Process for Formic Acid Production II: Reactive Dividing Wall Column without Uncontrollable Vapor Split

Abstract

A reactive dividing wall column (RDWC) integrates reactive distillation and multiproduct separation together, leading to the realization of process intensification. However, the reluctance to use it is due to the uncontrollable vapor split, which is self-regulated according to the flow resistance on each side of the partition wall. For some cases, the pressure of reaction and multicomponent separation is different, which results in an energy penalty if we directly integrate these units together, for example, formic acid (FA) production through methyl formate (MF) as presented in the part I of this series (Ind. Eng. Chem. Res. 2020, 59, 22215). To tackle these obstacles, a new reactive dividing wall column without the uncontrollable vapor split (NV-RDWC) by converting the bidirectional vapor–liquid thermal coupling to liquid-only transfer stream is proposed in this work. Optimization was first carried out by coupling the genetic algorithm (GA) and rigorous simulation. On the basis of the optimal solution, a detailed comparison was conducted between the conventional reactive distillation process, RDWC, and NV-RDWC, and the results show the superiority of NV-RDWC. Then two multiloop proportional-integral (PI) control structures and a model predictive control (MPC) for NV-RDWC were developed, respectively, to investigate their control performance. The dynamic response in the face of feed disturbance shows that MPC could give superior control performance for this complex coupled process.