基于响应曲面法的环管装置聚丙烯相对分子质量的模拟及优化

Optimization and Simulation of Relative Molecular Mass of Polypropylene Produced in a Loop Reactor by Response Surface Methodology

基于响应曲面法(RSM),采用5因素3水平的Box-Behnken设计,通过Aspen Polymers Plus软件模拟了环管式丙烯聚合过程,探讨了聚合温度、压力、丙烯质量流量、催化剂用量、H2体积分数对环管反应器出口聚丙烯(PP)相对分子质量的影响,建立了以环管反应器出口PP相对分子质量为响应函数的数学模型,对聚合反应条件进行了优化,确定了满足PP相对分子质量为(1.22±0.004)×105的最佳操作条件。结果表明,在聚合温度71.1℃、压力3.25MPa、丙烯质量流量6.71×103 kg/h、催化剂用量0.20kg/h、H2体积分数3.12%的最佳操作条件下,得到的PP相对分子质量为1.22075×105,与目标值的偏差仅为0.061%;采用响应面法优化环管装置生产具有目标相对分子质量PP的操作条件可行,建立的数学模型能够较准确地预测PP相对分子质量,可以用于指导工业生产。

On the basis of response surface methodology （RSM）, the process simulation for liquid phase bulk propylene polymerization in loop reactor by using Aspen Polymers Plus software was carried out. A five-factor, three-level Box-Behnken experimental design combined with RSM was employed to investigate the individual and interactive effects of temperature, pressure, mass flow of catalyst, mass flow of propylene, and H2 volume fraction on relative molecular mass（Mw） of PP. A quadratic model （R2=0.983） for the prediction and optimization of Mw of PP was developed. The optimization conditions were the temperature of 71.1℃, pressure of 3.25 MPa, catalyst mass flow of 0.20 kg/h, propylene mass flow of 6.71×10.3 kg/h, and H2 volume fraction of 3.12%, under which the obtained Mw was 1.22075×105, being very close to the aimed value of （1.22±0.004）×10.5 with the deviation of 0.061%. The developed model can be used to predict the Mw of PP in industrial production.