在液相本体法环管反应器聚丙烯生产过程中,聚丙烯颗粒粒径分布影响聚合速率、气力输送、后处理工序生产成本和最终的聚丙烯物性,特别是对后续工序有流化床烯烃共聚的工艺有重要影响。为预测环管反应器中聚丙烯的粒径分布,考察各操作变量和动力学参数对聚丙烯粒径分布的影响,运用了粒群衡算方法。在综合分析环管反应器中物料流型、聚丙烯颗粒动力学和聚丙烯颗粒生长的基础上,建立了稳态操作时聚丙烯颗粒粒径分布预测模型。模型计算结果表明,当单一粒径催化剂进料时,随着催化剂粒径或是预聚合与主聚合反应温度的增加,聚丙烯粒径分布向大粒径方向偏移,且分布变宽;相比于反应温度,催化剂粒径作用更为显著。同时发现,丙烯进料流速对聚丙烯粒径分布的影响很小。在催化剂粒径有分布的情况下,不同粒径催化剂的质量比不但影响聚丙烯的平均粒径,而且也影响其粒径分布曲线,并在一定的质量比下会出现双峰颗粒粒径分布曲线。In a propylene polymerization loop reactor,polymerization rate,fluid transport,and cost of post-treatment after polymeric process and polymer properties may be affected by polymer particle size distribution,especially when a co-polymerization technology including olefin polymerization fluidized-bed reactor is followed.In order to investigate the effects of operation parameters and kinetics parameters on the polypropylene particle size distribution in the loop reactor,a steady-state particle size distribution model was developed,in which the flow type in the loop reactor,polypropylene particle dynamics and the particle growth were taken synthetically into account based on the mass balance and solid population balance.The result showed that for uniform size catalyst feed,by increasing either initial catalyst size or the reaction temperature of the main polymeric reactor,the polypropylene particle size distribution in loop reactors became boarder and shifted to larger size,in comparison with the reaction temperature,the effect of catalyst particle size was obvious.The effect of propylene feed rate on polypropylene particle size distribution was much smaller.It's also shown that the ratio of catalyst masses with different sizes in the case of multi-size catalyst feed strongly affected not only the average polypropylene particle size,but also the particle size distribution in the loop reactor.Bimodal polypropylene particle size distribution can be obtained by using a catalyst feed with a distinct particle size distribution.国家自然科学基金(20406016);; 中国石油化工股份有限公司福建炼油化工有限公司项目(G7808-06-ZS-1006)资
