反应精馏合成乙酸异丙酯过程的强化与动态控制

Intensification and Dynamic Control of a Reactive Distillation Process for the Synthesis of Isopropyl Acetate

为了解决传统反应精馏难以得到高纯度乙酸异丙酯的难题,将反应精馏与萃取精馏工艺耦合在一个塔中,打破产物间的共沸,得到高纯度的乙酸异丙酯。同时采用萃取剂循环物流对异丙醇进行预热,以降低反应萃取精馏塔的再沸器热负荷。利用AspenPlus模拟软件对该流程模拟,得到乙酸异丙酯的摩尔分数可达99.5%,在此基础上以年度总费用(TAC)最小为优化目标,得到最优的操作参数。基于经济最优流程,对反应萃取精馏合成乙酸异丙酯流程进行控制结构的设计,采用相对增益矩阵(RGA)判据获得不同的操纵变量与控制变量匹配关系,提出了3种动态控制结构并对其动态特性进行了分析。结果表明,Q/F-温度串级控制结构可有效抵抗扰动,稳定后产品纯度偏差较小,且回稳时间相比温差控制更短,可以保证生产的平稳运行。

Often the conventional reactive distillation column cannot produce high purity isopropyl acetate (IPAc).In this work,the reactive distillation and extractive distillation were integrated into one column to obtain high purity IPAc,and the inlet isopropanol was preheated to reduce the reboiler heat load of reactive and extractive distillation column.Subsequently,the process was simulated by the Aspen Plus software,and the results show that the molar fraction of IPAc reaches 99.5%.The optimal operating conditions are obtained with the minimum total annual cost (TAC) as the target function.Based on the steady-state simulation design data,the control structures were designed for reactive and extractive distillation processes.Different matching relationships between manipulate and control variables are determined through the relative gain array (RGA) criterion,and the dynamic characteristics of three control structures were analyzed.The results indicate that the Q / F -temperature cascade control has a shorter settling time and less purity deviation than the temperature difference control structure,which can handle the disturbances effectively and keep the process running smoothly.