气相流化床聚乙烯颗粒粒径分布模型的研究  

Simulation of Particle Size Distribution in Gas Phase Ethylene Polymerization Fluidized-Bed Reactor

作　　者：杨宝柱[1] 江炜[1] 王靖岱[1] 阳永荣[1] 

机构地区：[1]浙江大学化学工程与生物工程学系,浙江杭州310027

出　　处：《高校化学工程学报》2005年第4期461-467,共7页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学重大基金资助项目(20396009)。

摘　　要：气相法流化床聚乙烯生产过程中,聚乙烯颗粒粒径分布影响聚合速率、脱挥速率、后处理工序生产成本和最终的聚乙烯物性。为预测流化床中聚乙烯的粒径分布,考察各操作变量和动力学参数对粒径分布的影响,运用了质量衡算的方法,在综合分析聚合过程中聚乙烯颗粒的生长、磨损和扬析等行为的基础上,建立了稳态操作时聚乙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操作气速的增大,聚乙烯粒径分布向大粒径方向偏移,且分布变宽;相比于操作气速,催化剂粒径作用更为显著。同时发现,床层压力和温度对聚乙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树脂的平均粒径,而且也影响树脂的粒径分布曲线,并在一定的配比下会出现双峰颗粒粒径分布曲线。最后,对某聚乙烯厂家的流化床反应器的聚乙烯颗粒粒径分布进行了模拟计算,计算结果与实验数据基本一致,说明该模型较好反映了气相流化床反应器的反应历程和规律,具有良好的工业应用前景。In gas phase polymerization fluidized-bed reactor (FBR), polymerization rate, devolatilization rate, cost of post-treatment after polymeric process and polymer properties may be affected by polymer particle size distribution. In order to simulate the polyethylene particle size distribution (PSD) in FBR and investigate the effects of operation parameters and kinetic parameters on PSD, a steady-state particle size distribution model was developed. Based on the mass balance and solid population balance, the model synthetically takes into account the particle growth, attrition and elutriation. The result shows that for uniform size catalyst feed, by increasing either initial catalyst size or superficial gas velocity, the PSD in bed becomes boarder and shifts to larger size. The effect of bed temperature and pressure on PSD can be neglected. It's also shown, the different size catalyst weight ratio in case of multi-size catalyst feed strongly affects PSD in bed. Bimodal PSD can be obtained by using a catalyst feed consisting of multiple distinct but uniform catalyst size. The polyethylene PSD in the industrial fluidized bed reactor could be predicted by this model with fairly good accuracy.

关 键 词：气相流化床 聚乙烯 粒度分布 模型 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业] TQ316.314