节能环保型甲醇精馏装置的流程模拟与优化

Process simulation and optimization of energy-saving and environment-friendly methanol distillation device

以某厂100万t/a双效节能型甲醇精馏装置为研究对象,采用流程模拟软件Aspen Plus进行流程模拟,模拟结果与实际值吻合良好。在此基础上,分别对预精馏塔、加压塔、常压塔和回收塔的工艺参数进行优化,优化后的工艺参数为预精馏塔萃取水流量为9200kg/h(占粗甲醇进料的7.3%),加压塔操作压力为800kPa,常压塔侧线采出位置为第61块板(从塔顶往下数),回收塔质量回流比为6.9。此外,对流程进行了适当优化,增加预精馏塔尾气水洗装置,进一步回收尾气中残余甲醇,达到节能环保要求。通过工艺参数优化和流程优化,产品中甲醇质量分数达到99.9%,乙醇质量分数低于10×10^(-6),甲醇回收率提高1.0%,甲醇精馏装置总能耗降低11.1%。

Process simulation of double-effect and energy-saving methanol distillation device with an output capacity of 1Mt/a was carried out by using Aspen Plus simulation software. Simulation results agree well with the actual case. On this basis, process parameters of the pre-distillation column, pressurized column, atmospheric column and methanol recovery column were investigated. The optimum results were determined as follows：the rate of extraction water of the pre-distillation column is 9200kg/h; the operation pressure of pressurized column is 800kPa; the draw-out position of atmospheric column is 61st; and the reflux ratio of methanol recovery column is 6.9. Besides, for energy-saving and environment-friendly requirement, process optimization for the pre-distillation column was carried out： adding an incondensable gas water washing device to recover methanol. Under the optimized process parameters, methanol mass fraction of the product can reach 99.9% with an ethanol mass fraction of below 10×10^-6, and the recovery ratio of methanol increases by 1.0%, while the heat duty of methanol distillation unit is reduced by 11.1%.