聚丙烯反应器稳定性分析

建立了针对本体法连续搅拌槽式聚丙烯反应器 (CSTR)的动态机理模型 ,并在定态点处进行线性化处理 ,以建立线性化模型 ,从工艺和控制角度对聚丙烯反应器的稳定性进行了全面分析。结果表明 ,丙烯聚合这种非线性、强放热、开环不稳定的CSTR与理想的CSTR有着很大的不同 ,放热速率不仅是温度的函数 ,而且受丙烯浓度、催化剂浓度的影响也很大。反应过程中转化率很低 ,再加上丙烯的临界温度也很低 ,温度升高会使冷凝潜热减少 ,单靠夹套冷却水难以移走反应热 ,从而造成高温稳态点 (开环稳定点 )的不存在。在假稳态的操作点处 (开环不稳定点 ) ,系统受到扰动而使温度升高 ,如不加任何控制将导致反应器烧毁。如果进料温度、催化剂初始浓度等发生变化也将导致假稳态点的变化 ,这时如果仍然按着原来的操作点进行操作 ,势必造成反应温度波动 ,影响产品质量

Stability analysis of polypropylene reactor

A dynamic mechanism model and its linearized model for the continuous stirred tank reactor of propylene liquid-phase bulk polymerization were developed. Based on the models, the process and control stabilities of polypropylene reactor were analyzed. The results showed that the exothermal rate was not only the function of temperature but also affected by the concentrations of propylene and catalyst. Because the propylene conversion rate and its critical temperature are very low, rising in temperature can result in the decrease of the latent heat of propylene. It is very difficult to remove the reaction heat only by the cooler water in the jacket of the reactor, thus a high-temperature steady state in ideal CSTR is hard to occur. At the mid-temperature pseudo-steady state, the temperature of the disturbed reactor may quickly increase and even make the reactor burned out, if there is no any control. The middle pseudo-steady point is not constant. If the feed temperature and the initial concentration of catalyst change, this middle pseudo-steady point will also change. If the operation runs at the former point, it will cause fluctuation of reaction temperature and has a bad effect on the product quality.