乙二醇与乙酸酯化反应的双反应段反应精馏塔的控制

Control of reactive distillation columns with single and double reactive sections for esterification of ethylene glycol with acetic acid

针对乙二醇(EG)与乙酸(AA)的两步连续酯化反应,以年总成本(TAC)最小为目标,对单反应段反应精馏塔(RDC-SRS)和双反应段反应精馏塔(RDC-DRS)过程进行了优化。结果显示RDC-DRS有更好的节能特性,这是由于其有更多的自由度来增强反应操作和分离操作的内部物质耦合和能量耦合。采用浓度控制方法设计了RDCSRS和RDC-DRS的控制方案,并比较了其动态特性;在出现进料流量扰动和产品组分扰动时,RDC-DRS都要好于RDC-SRS,且流量扰动更大时,其优势更明显,表明在分离两步连续反应时,RDC-DRS是更好的方案。

Two reactive distillation columns with single and double reactive sections( denoted RDC-SRS and RDCDRS,respectively) have been employed for the esterification of ethylene glycol with acetic acid,a reaction that involves a two-stage consecutive reversible reaction. The two processes have been optimized by minimizing the total annual cost. The RDC-DRS was found to require less capital investment and had lower utility consumption than the RDC-SRS. This is due to the fact that the former involves a higher degree of freedom than the latter,which enhances the integration of internal mass and energy transfer between the reaction and separation processes. In terms of a direct composition control strategy,the dynamic controllability of the RDC-SRS and RDC-DRS has been further studied and compared. The RDC-DRS was found to be superior to the RDC-SRS because of step disturbances from the feed flow rate and product purity set-points in the latter. That indicates that the RDC-DRS should be viewed as a better option for the separation of the two-stage consecutive reversible reaction and its complex reaction mixture.