双环管PP装置带连接堵塞原因及改进措施

在双环管聚丙烯(PP)装置上,可切换生产无规共聚PP和均聚PP产品,但无规共聚PP产品中乙烯含量过高、转产过程过快以及工艺参数控制不合适等都会导致PP装置的带连接堵塞;根据带连接堵塞的原因,从工艺参数和工艺流程两方面进行了改进。结果表明:采取降低无规共聚PP中乙烯质量分数为3. 0%～3. 5%,转产过程中乙烯含量为零时再调整给电子体加入量、适当调整装置工艺参数等措施,可保证PP装置的长周期稳定运行;在带连接的上游端加装一条冲洗丙烯的管线加快带连接内物料的流速,从而减少带连接堵塞的危险;在第二环管反应器返回第一环管反应器的带连接末端加装一个球阀,可及时地处理带连接堵塞;进一步的改进是在两环管反应器之间加装桥连接,以实现在线处理堵塞的带连接。

Reasons and countermeasures for belt connection blockage of dual-loop polypropylene plant

A dual-loop polypropylene(PP)plant can be used to alternatively produce random copolymer PP and homopolymer PP.However,the belt connection blockage could be caused by the extremely high ethylene content of random copolymer PP,extremely fast production conversion and inappropriate process parameters control.The innovation countermeasures could be conducted from two aspects of process parameters and technological process based on the reasons for belt connection blockage.The results showed that the long-term steady operation of PP plant could be guaranteed by reducing the ethylene mass fraction of random copolymer PP to 3.0%-3.5%,adapting electron donor addition during the production conversion at the ethylene content of zero,and appropriately adjusting the process parameters;a flushing pipeline for propylene can be installed at the upstream end of the belt connection to accelerate the flow rate of the material inside,thereby reducing the risk of the belt connection blockage;a ball valve can be installed at the end of the backward belt connection from the second loop reactor to the first loop reactor in order to timely solve the belt connection blockage;and the further countermeasure is to install a bridge connection between the two reactors in order to realize the on-line blockage resolution.