Novolen气相聚丙烯装置长周期运行分析及对策

Analysis of Long-period Operation of Novolen Gas-phase PP Plant and Countermeasures

锦西石化15×104t/a气相聚丙烯装置,采用ABB公司的Novolen工艺。装置自开车运行以来,受反应器温度波动较大、反应聚合物结块、聚合物细粉较多等问题的制约,一直未能实现长周期平稳运行。对此,改进反应器温度和料位参数控制,降低催化剂进料量和浓度对反应温度的影响;同时,严格控制原料丙烯质量,加强质量监测分析,确保丙烯中催化剂毒物COS、CO2、AS、CO、硫、甲乙醇、H2O含量在控制指标范围内,保证丙烯纯度不低于99.5%。选用高品质聚合催化剂,采用催化剂中部进料方式,优化调整聚合反应器各路丙烯流量和助催化剂TEA加入量,载气压缩机入口增加精密过滤器并及时切换清理,反应器卸料阀增加电伴热。通过以上改进,解决了聚丙烯装置反应器温度波动大、聚合物结块、细粉问题,该装置2013年上半年实现长周期连续平稳运行139d,能耗和三剂消耗明显降低。

PetroChina Jinxi Petrochemical Company＇s 15xl＆t/a gas-phase polypropylene unit uses ABB＇s Novolen technology.Due to a series of problems such as large fluctuations in reactor temperature,agglomeration of reaction polymers and large amount of fine polymer powder,the unit had never achieved long-time stable operation since it was put into use.To solve these problems,technicians improved the temperature for the reactor and material level parameter controls to reduce the influence of the volume and concentration of fed catalyst on reaction temperature.In addition,they strengthened the control of quality of feedstock propylene by tightening quality monitoring and analysis to ensure that the contents of catalyst toxicants in the propylene such as COS,CO2,AS,CO,sulfur,methanol,ethanol and H20 were within the control ranges and that the pu- rity of propylene was not less than 99.5%.Other optimizations included using high-quality polymerization cata- lyst,feeding catalyst in the middle section,optimizing propylene flows and the dose of the promoter TEA in polymerization reactor, adding a precision filter at the inlet of the carrier gas compressor and cleaning the filter in a timely manner,and adding electric heat tracing for the discharge valve of the reactor.The above optimizations solved the issues of large fluctuations in the reactor temperature,polymer agglomeration and presence of fine powder for the polypropylene unit.As a result,the unit operated steadily for 139 consecutive hours during the first half of 2013 and its consumption of energy,catalyst,solvent and additives all dropped significantly.