以丙三醇为溶剂连续萃取精馏分离乙腈-水

Separation of Acetonitrile-water by Continuous Extractive Distillation with Glycerol as Solvent

本文采用化工流程模拟软件Aspen Plus V7.3对乙腈—水共沸体系的萃取精馏过程进行了模拟与优化。通过绘制拟二元气液平衡相图,筛选出合适的萃取剂为丙三醇。确定了双塔连续萃取精馏的工艺流程,并利用灵敏度分析工具考察了萃取精馏塔的全塔理论板数、回流比、溶剂比(萃取剂对原料的摩尔比)、萃取剂进料位置、原料进料位置对分离效果的影响。确定的最佳工艺方案为:全塔理论板数为14,回流比为0.25,溶剂比为0.5,原料和萃取剂分别在第10块和第3块理论板进料。在此工艺条件下:萃取精馏塔塔顶乙腈的纯度达99.99%,萃取剂再生塔塔顶水的纯度达到99.96%。模拟与优化结果为乙腈—水共沸体系萃取精馏过程的设计提供了参考。

Extractive distillation process for acetonitrile -water azeotropic system was simulated and optimized using Aspen Plus V7.3. By the pseudo-binary phase diagram, glycerol was selected as a suitable extractant. The process of continuous extractive distillation with two columns was confirmed. The separation effect of the number of theory stages, the mixture feed stage, the solvent feed stage, the reflux ratio and the mole ratio of extractant to mixture （sol-vent ratio） were investigated using sensitivity analysis tool. The optimal condition for the extractive distillation is as follows： the number of theory stages is 14, the mixture feed stage is 10th, the solvent feed stage is 3rd, the reflux ratio is 0.25, and the solvent ratio is 0.5. Under the technological condition： the separation effect of acetonitrile of extrac-tive distillation tower top is up to 99.99%. The purity of water of the extractant- recovery column is 99.96%. The re-sults are useful for the design of extractive distillation process for acetonitrile-water azeotropic system.