基于MVR热泵精馏的乙醇-异丙醇分离工艺

Research on technologies for separating ethanol and isopropanol based on the MVR heat-pump distillation

常规精馏分离乙醇-异丙醇小温差体系的能耗较高,为此本文将两种机械蒸汽再压缩(MVR)热泵精馏工艺,即塔顶蒸汽直接压缩供热和塔底液相闪蒸压缩供热精馏工艺应用于乙醇-异丙醇的分离研究。利用Aspen Plus化工流程模拟软件中的严格精馏模块RadFrac.和压缩机模块Compr.,选用Wilson-RK方程计算物性数据,以分离过程的能耗最低为目标函数,对以上提出的两种MVR热泵精馏工艺分别在不同操作压力工况条件下进行了模拟与优化,得到了各自相关的工艺参数和设备参数。研究结果表明:与常规精馏工艺相比,以上两种MVR热泵精馏工艺节能分别为93.2%和93.4%。利用模拟得到的相关数据,估算了以上两种MVR热泵精馏工艺的平均年总费用,并进行了综合经济效益评价。结果表明:以上两种MVR热泵精馏工艺的平均年总费用基本持平,因此以上两种MVR热泵精馏工艺均是分离该体系较为合适的方法。

Because high energy consumption for separation of small temperature difference system such as ethanol and isopropanol has been always a problem in the separation process of ethanol and isopropanol,this paper investigated two kinds of mechanical vapor recompression （MVR） heat-pump distillation processes, tower top vapor recompressed heat-pump distillation and tower bottom liquid flash recompressed heat-pump distillation. Based on the minimum energy consumption for separating ethanol and isopropanol,the simulations for the two schemes were performed by Aspen Plus with the Radfrac. module Compr. module and Wilson-RK equation. The suitable operating parameters and device parameters were obtained under different operating pressure conditions. The research showed that the two MVR heat-pump distillation processes can save energy by 93.2%and 93.4%respectively compared with the conventional distillation process. The average annual total cost（ATC） for the two MVR heat-pump distillation processes was estimated based on the simulation results,and the overall analysis of economic benefits was evaluated. The results showed that the ATC for the two MVR heat-pump distillation processes were similar,indicating both schemes would be suitable for the separation of ethanol and isopropanol.