萃取精馏分离环氧丙烷-水-甲醇混合物的模拟

采用化工流程模拟软件Aspen Plus,以NRTL模型计算气液平衡,对萃取精馏分离环氧丙烷-水-甲醇混合物的过程进行模拟。选择1,2-丙二醇为萃取剂,考察了萃取剂与原料的质量比(溶剂比)、萃取精馏塔理论塔板数、粗环氧丙烷进料位置、萃取剂进料位置、萃取剂进料温度和回流比对分离效果的影响。模拟结果表明,在满足环氧丙烷产品纯度为99.99%(w)的条件下,优化的工艺条件为:溶剂比0.45,萃取精馏塔理论塔板数30块,粗环氧丙烷进料位置第20块塔板,萃取剂进料位置第5块塔板,萃取剂进料温度45℃,回流比0.14。在此工艺条件下,环氧丙烷回收率为99.99%,单位产品热负荷为0.936 GJ/t。

Simulation of Separating Propylene Oxide-Water-Methanol Mixture by Extractive Distillation

An extractive distillation process with two columns and propylene glycol(PG) as the extractant for separating propylene oxide(PO)-water-methanol mixture was simulated by using Aspen Plus process simulation software and NRTL model.The effects of major design parameters,such as mass ratio of extractant and feed(solvent ratio),theoretical tray number of extractive distillation column,crude PO feeding position and extractant feeding position,extractant feeding temperature and reflux ratio,on the separation were investigated.Aimed at PO mass fraction of 99.99%(w) in the product,the optimal process conditions were solvent ratio of 0.45,theoretical tray number of extractive distillation column of 30,crude PO feeding position of the 20th tray,extractant feeding position of the 5th tray,extractant feeding temperature of 45 ℃ and reflux ratio of 0.14.Under the conditions,the PO recovery ratio and the heat duty for per ton product reached 99.99% and 0.936 GJ/ t,respectively.