萃取与精馏耦合分离苯-甲醇的研究

Study on separation of benzene and methanol by coupled extraction with distillation

研究了萃取与精馏耦合法用于苯-甲醇共沸物中的甲醇回收。通过实验手段从萃取剂选择、萃取比及萃取温度变化3个角度对萃取效果进行考察。实验结果表明,水的萃取效果最好,在操作温度35℃下,萃取比1∶1时,甲醇萃取分配系数为40. 0,选择性系数4 260. 8。在此实验数据上,提出以水为萃取剂的萃取与精馏耦合分离工艺流程,并运用流程模拟软件进行3塔连续模拟计算,得到了优化的工艺条件。模拟结果表明,当甲醇塔(T1)理论塔板数为15块、回流比为2,萃取塔(T2)理论塔板数为4块,回收塔(T3)理论塔板数为20块、回流比为2时,可得质量分数在99. 5%以上的苯和甲醇成品。

The extraction and rectification coupling method is used to recover methanol from benzene-methanol azeotrope.The extraction effect is investigated through experimental means from three aspects including extractant selection,extraction ratio and extraction temperature change.The experimental results show that the extraction effect by using water as extractant is the best.Distribution coefficient of methanol extraction is 40.0 and the selectivity coefficient is 4 260.8 when the extraction ratio is 1∶1 and the operating temperature maintains at 35℃.Based on these experimental data,the extraction and rectification coupling process with water as extractant is proposed,and the optimized process conditions are obtained by performing three-tower continuous simulation calculation through using the process simulation software.The simulation results show that benzene and methanol respectively with a mass fraction of 99.5%or more can be gained when the theoretical plate number and the reflux ratio of the methanol tower(T1)is 15 and 2 respectively;the number of theoretical plates of the extraction tower(T2)is 4;the theoretical plate number and the reflux ratio of the recovery tower(T3)is 20 and 2,respectively.