基于Aspen plus萃取精馏的概念设计及优化

Concept design and optimization by Aspen Plus for extractive distillation

本文利用Aspen Plus软件,以醋酸-水体系为例,概念设计和优化萃取精馏过程。热力学模型选择NRTL活度系数方程和Hayden-O'Connell逸度系数方程,采用Aspen Plus的DSTWU模块,确定萃取精馏塔和溶剂回收塔的初始参数。在初始参数下,利用Aspen Plus的RadFRac模块对2塔精算,并利用Sensitivity模块,分别优化2塔的原料和萃取剂进料位置、回流比、萃取剂对原料的进料比等参数。设计和优化结果为:萃取精馏塔塔板数为30,原料进料板为第8块,萃取剂的进料板为第3块,回流比为3,萃取剂与原料进料比(质量)为1.6;溶剂回收塔塔板数为20,进料板为第7块,回流比为2。此参数下,利用RadFRac模块进行全流程模拟,结果显示,产品冰醋酸的质量分数达0.9975,2塔再沸器总热负荷为6545 kW,生产1t冰醋酸耗费蒸汽(1MPa)量为4.25t,与文献报道的普通精馏过程相比,可节约能耗52.23%。概念设计和优化的结果对工业化设计和生产具备指导意义。

Using Aspen Plus software,concept design and optimization for extractive distillation was executed with HAc-water system as examples in this paper.Thermodynamic models were chosen as NRTL equation for activity coefficient and Hayden-O＇Connell equation for fugacity coefficient.Initial parameters of extractive distillation column and recovery column were obtained by DSTWU model of Aspen Plus.In the initial parameters,rigorous calculation was executed by RadFRac model and sensitivity model was used to optimize the parameters such as feed stage,extractant stage,reflux ratio,and ratio of extractant to feed of the two columns.The results of design and optimization show that parameters of extractive distillation are as follows：stage number is 30,feed stage is 8,extractant stage is 3,reflux ratio is 3,ratio of extractant to feed is 1.6,and parameters of recovery column are as follows：stage number is 20,feed stage is 7,reflux ratio is 2.In the optimized parameters,full flow simulation was executed by RadFRac model.The results show that product mass fraction of HAc could reach 0.997 5 and total reboiler＇s heat duty of the two towers was 6 545 kW.Consumption of heating steam was 4.25 t per ton of HAc,which was reduced by 52.23%in comparison with traditional distillation reported in literature.The results of concept design and optimization will provide fundamental guide for the industrial design and productionproducing.