冷凝模式下降低Unipol工艺聚乙烯树脂灰分的方法

对Unipol气相流化床反应器冷凝操作时聚乙烯树脂灰分增加的原因进行了分析。树脂灰分是催化剂的残留物,其增加的主要原因是:随空时收率的增加,催化剂在反应器内的停留时间缩短,使催化剂的活性不能充分发挥;冷凝操作使反应器内温度分布梯度加大,在偏离最佳反应温度的情况下,催化剂活性达不到最高;助催化剂过量或不足;原料杂质含量的增加造成催化剂及助催化剂用量的增加。采用新型催化剂、改进常规催化剂、优化工艺操作条件等措施可以降低树脂灰分,其中采用淤浆催化剂可使树脂灰分降低60%～70%。

Reducing Ash Content of Unipol Polyethylene in Condensate Mode of Operation

Reasons of ash content increasing in Unipol polyethylene produced from gas fluidized bed reactor and operated in condensate mode,were analysed. The main reasons were as follows:residence time of catalyst reduced with increasing space-time yield so that catalyst could not take full effect;in condensate mode operation,increase of temperature gradient in reactor affected catalyst activity;the co-catalyst was in excess or in deficiency;increase of impurity content in raw material led to excessive catalyst and co-catalyst to be consumed.Measures proposed to reduce ash content in PE product were: adopting new catalyst,improving conventional catalyst,and optimizing process conditions.The ash content could be reduced 60%—70% by using slurry catalyst.