丙酮-甲醇混合物萃取精馏分离过程合成与模拟

Synthesis and Simulation of Extractive Distillation Separation Process for Acetone-Methanol Mixture Stream

当混合物组分之间的挥发性相近并且形成非理想溶液,组分间的相对挥发度可能小于1.1,采用常规精馏分离就可能不经济,若组分间形成恒沸物,仅采用常规精馏达不能实现相应组分的锐分离,这种情况可考虑采用强化精馏来实现相应组分之间的分离。用水作为溶剂对流量为40mol/s的丙酮-甲醇(摩尔比为3∶1)混合物流股进行萃取精馏过程合成设计与模拟计算。分离流程采用两塔结构,即萃取精馏塔和溶剂回收塔,前者塔顶馏出产物为丙酮,塔底产物为甲醇、水和微量丙酮的混合物;后者塔顶馏出产物为甲醇,塔底为溶剂水,此塔底产物作为回流与补充溶剂合并返回萃取精馏塔。经过试探法合成,萃取精馏塔采用30块理论板(包括塔顶全凝器和塔底再沸器),溶剂进料板为第7块(从上往下数),丙酮-甲醇混合物流股进料板为第13块,回流比为4,塔顶产物31.226mol/s,丙酮纯度95.5%,塔底产物69mol/s;溶剂回收塔为简单精馏塔,采用16块理论板(包括塔顶全凝器和塔底再沸器),进料位置为第12块,回流比为3,塔顶产物流量为10 mol/s,甲醇含量99.8%,塔底产物流量59mol/s,水含量达到99.9%,补充溶剂约为1 mol/s,实际补充量可根据操作情况适当变化。

Synthesis and simulation of acetone - methanol mixture stream （ mol ratio of 3 ： 1 ） with a total flow rate of 40mol/s separation process was conducted via extractive distillation method using water as solvent. The separation process employed two -column topology structure, i.e. extract distillation column and solvent recov- ery column. The former obtained a top product of nearly pure acetone and a bottom product of a mixture consis- ting of water, methanol and minute acetone, whereas the latter gave a top product consisting mainly of methanol and a bottom product of nearly pure water for recycling to the former combining with the makeup water. Through the synthesis of attempting method, extractive distillation column was equipped with 30 theoretical stages （inclu- ding condenser and reboiler）, with the solvent and acetone -methanol mixture feed stage being 7 and 13 （from top） respectively. The reflux ration is 4 and the distillate flow rate is 31. 226mol/s with acetone purity of 95. 5%. The flow rate of bottom product is 69mol/s. The solvent recovery column is ordinary distillation tower with 16 theoretical stages （ including condenser and reboiler）, with the feed stage being 12 and reflux ratio being 3.The flow rate of distillate is 10 mol/s with methanol purity of 99.8%. The bottom product flow rate is 59mol/s with water purity of 99.9%. The makeup water is about 1 mol/s and the actual complementary water could be varied according to operation conditions.