分隔壁萃取精馏塔分离乙酸乙酯-异丙醇

Separation of Ethyl Acetate-Isopropyl Alcohol by Extractive Dividing Wall Column

采用分隔壁萃取精馏塔,以乙二醇为溶剂将乙酸乙酯与异丙醇分离。基于装置的实际条件进行Aspen Plus模拟,考察溶剂比、溶剂温度、回流比等条件对其分离效果的影响,同时评估其经济性。模拟得到理想的操作条件为左回流比3.5、右回流比1.5、溶剂比4、溶剂温度90℃、混合物进料位置偏下。模拟结果表明,溶剂比和左侧回流比、左侧回流比和右侧回流比在操作上存在关联;其他条件一定时,溶剂温度存在唯一值,使得两侧产品的质量分数同时达到最优;分隔壁塔与常规流程相比在经济性上具有很大优势,可节能11%和降低25%设备费。用实验验证模拟结果时,右侧产品质量分数偏低,但可通过调节右侧回流比解决这个问题。最终达到左侧出料乙酸乙酯的质量分数为98.82%,右侧出料异丙醇的质量分数为97.88%。

An extractive dividing wall column （EDWC） was established and used for separating ethyl acetate-isopropyl alcohol （EA-IPA）. Operation conditions including solvent ratio, solvent temperature, reflux ratio and etc. were investigated by using ethylene glycol as solvent. Based on the actual conditions of the EDWC, simulations were run to obtain ideal operating conditions, and economies of EDWC was also evaluated. The ideal operation conditions were left reflux ratio of 3.5, right reflux ratio of 1.5, solvent ratio of 4, solvent temperature of 90℃ and feed location of EA-IPA mixture at lower position. The simulation result revealed that there existed operation relationship between left reflux ratio and solvent ratio. Solvent temperature should be fixed when other conditions were given so that the purities of left and right distillations could be maximized at the same time. EDWC had a great advantage in economics with energy consumption reduced by 11% and capital cost shorted by 25%, compared with conventional extractive distillation. Experimental results conducted based on simulation results showed that the purity of the right distillation was lower than the simulation results, which could be solved by adjusting right reflux ratio. Finally, the mass fraction of EA in the left distillation was 98.82%, and that of IPA in the right distillation was 97.88%.