乙苯工艺中苯精制单元动态仿真与控制优化

Dynamic simulation and control optimization of the benzene refining unit in an ethylbenzene process

乙苯是重要的有机化工原料,国内需求量大但产能不足。在苯与乙烯烷基化制取乙苯工艺中,苯精制单元作为全流程的起点,为其余单元提供原料,该工段耦合性强、控制难度大。以某企业年产50万吨乙苯工艺为研究对象,对苯精制单元建立动态模型,就该工艺单元的控制方案进行分析与优化。针对原控制方案在进料量发生波动时不能对塔釜组成变化作出快速响应的问题,提出了新的控制方案。通过对比分析,最终选定以灵敏板温度为主控变量来控制塔釜采出,仿真结果表明改进后的控制方案在产品纯度的控制上效果显著。

Ethylbenzene is an important organic chemical raw material.Although domestic demand in China is high,the production capacity is insufficient.In the formation of ethylbenzene by alkylation of benzene with ethyl-ene,the benzene refining unit serves as the starting point of the whole process and provides feeds for the remaining units.However this section has strong coupling and is difficult to control.In this work,an enterprise with an annual output of 500000 tons of ethylbenzene is chosen as the research object,a dynamic model of the benzene refining unit is established,and the control scheme of the process unit is analyzed and optimized.In an attempt to overcome the problem that the original control scheme cannot respond quickly to the changes in the composition of the tower when the feed volume fluctuates,a new control scheme is proposed.Through a comparative study,the temperature of the sensitive tray is selected as the main control variable to control the extraction at the bottom of the tower.The simulation results show that the improved control scheme is more effective in allowing control of product purity.