燃料乙醇精馏工艺的模拟优化与节能研究

Research on the Simulation & Optimization and Energy Saving of Extractive Distillation in Fuel Ethanol Production

将工业乙醇生产的一级精馏系统和燃料乙醇生产的加盐萃取精馏系统合并,在差压精馏节能技术的基础上,利用过程系统模拟软件ProII对蒸馏工艺进行模拟优化。醪塔:最佳理论塔板数为15块,塔顶压力为50 kPa;精馏塔:最佳理论塔板数为30块,塔顶压力为200 kPa,回流比为3.4;萃取精馏塔:塔顶产品乙醇体积浓度为99.8%(优级纯)时,所需最佳理论塔板数为30块,回流比为0.4,萃取剂和酒精质量比为1.2∶1;萃取剂回收塔:在塔釜液含水量为0.2%(w/w)的前提下,最佳理论塔板数为10块,回流比为0.5。另外,采用热能耦合、闪蒸技术、设置中间再沸器等一系列节能措施,结合燃料乙醇生产的蒸煮工段,对热量进行充分利用,使冷却水以及加热蒸汽的用量大大减少。

The first-grade distillation system in industrial ethanol production and the salt-added extractive distillation system in fuel ethanol pro-duction were combined together and the distillation process was simulated and optimized by simulation software ProII on the basis of the ener-gy-saving technique of differential pressure distillation.The optimized technical parameters were summed up as follows： prefractionator： the best theoretical number of trays was 15,and the top pressure was 50 kPa;distillation column： the best theoretical number of trays was 30, the top pressure was 200 kPa, and the reflux ratio was 3.4; extractive distillation column： when the ethanol volume concentration of the top product got 99.8% （superior grade pure）, the best theoretical number of trays was 30, and the reflux ratio was 0.4, the mass ratio of extractant and alcohol was 1.2：1 ; extractant recovery tower： when water content in the bottom product was 0.2 %（w/w）, the best theoretical number of trays was 10, and the reflux ratio was 0.5. Besides, a series of energy-saving measures were also adopted such as thermal energy coupling, flash steaming technique, and the installment of middle reboiler. In combination with the cooking procedures in fuel ethanol production, the heating energy was fully utilized so that the consumption of cooling water and heating steam were greatly reduced.