间歇萃取精馏分离二氯甲烷-乙醇-水体系的模拟及实验研究

基于NRTL模型,以乙二醇为萃取剂,用Aspen Plus软件对二氯甲烷-乙醇-水三元体系间歇萃取精馏过程进行模拟,分别考虑了溶剂比、回流比、塔板数、溶剂进料位置和溶剂进料温度对整个精馏过程的影响.原料为100 kg含95％二氯甲烷(质量分数)、3％水、2％乙醇的混合溶液,利用模拟结果对各工艺参数进行分析和优化,得出了最佳的操作条件:精馏塔塔板数为20块、溶剂进料位置在第2块塔板、溶剂进料温度为38℃、回流比为2.5、溶剂比为0.575.在该操作条件下,塔顶的二氯甲烷的质量分数可达99.8％以上,回收率为96.65％,满足溶剂回收再利用的要求.通过实验对该模拟结果进行验证,得到的二氯甲烷质量分数高达99.8％,回收率为90％左右,与模拟结果基本一致.

Simulation and experimental study on batch extractive distillation for dichloromethane-ethanol-water

Using glycol as extraction agent,based on the non-random two-liquid(NRTL) model,Aspen Plus software is employed to simulate the batch extractive distillation process of dichloromethane-ethanol-water.The feed is 100 kg aqueous solution of dichloromethane-water-ethanol(mass ratio is 95∶3∶2).Taking solvent ratio,reflux ratio,number of plates,solvent feeding position and solvent feeding temperature into consideration,the optimum operating conditions are obtained: The number of tower plates is 20;the solvent feeding position is the second tower plate;the solvent feeding temperature is 38 ℃;the reflux ratio is 2.5;the solvent ratio is 0.575.Under these circumstances,the overhead fraction of dichloromethane is up to 99.8% and the recycling rate is up to 96.65%,fulfilling the requests of recycle.To verify the simulation results,the experiment is carried out.The mass fraction of dichloromethane is up to 99.8% and the recycling rate is about 90%,which are basically the same as the simulation results.