苯乙烯工业预聚过程牌号切换策略研究

Grade Transition Policy Research of Pre-polymerization of Styrene on Plant Scale

对苯乙烯热引发工业预聚动态过程进行了模拟,反应器出口固含量以及聚合物重均分子量的模拟结果与工业装置采集数据的误差在5%以内。考察了反应温度、进料流量、进料配比对单体转化率和聚合物重均分子量的影响规律, 其中反应温度对单体转化率和聚合物重均分子量的影响最大,进料流量次之。据此提出了多个牌号切换过程的策略,并与工业切换方案及温度阶跃变化方案进行比较。结果表明温度过调策略可以使过渡时间缩短和减少过渡料。最优切换策略的过渡时间和过渡料较工业切换方案减少了81.3%而较温度阶跃变化方案减少了47.5%。

A dynamic model was developed for an industrial styrene pre-polymerization process. Calculated weight fraction and weight average molecular weight (Mw) of polystyrene in the outlet stream are all in good agreement with industrial data. The influence of operation parameters such as temperature, total input flux and weight fraction of monomer in feed flow on conversion rate and Mw was investigated with steady-state model. Temperature was found to be a most sensitive parameter for weight fraction and Mw, and the total input flux was the most inactive parameter. According to sensitivity analysis, various grade transition policies for pre-polymerization reactors were put forward. Compared with the industrial way, the transition time of the optimized policy might be shortened 81.3%. Compared with the step changes to the set-points strategy, the transition time and off-specification product of the optimized policy might be shortened 47.5%. The results indicate that over-change of temperature could reduce off-specification product and shorten transition time.