催化裂化装置烟气轮机结垢原因分析与对策

Causes analysis and countermeasure of fouling in flue gas turbine of RFCCU

2010年5月起,中国石油化工股份有限公司武汉分公司2号催化裂化装置出现了烟气轮机结垢问题,因此导致停机21次,为满足长周期运行的要求,装置做出多项调整和改造.总结自2010年至2016年针对烟气轮机结垢问题采取的一系列改造措施:降低烟气轮机入口烟气中细粉浓度,减少催化剂的黏连性,改善烟气轮机内的环境.发现烟气轮机结垢的关键原因是原VAS-250型第三级旋风分离器设计值与实际工况不匹配,实际烟气流量仅为原设计值的77%,烟气线速低,分离效率低,烟气轮机入口催化剂细粉质量浓度156 mg/m3,小于10μm颗粒仅占86%,低于烟气轮机设计要求.2016年6月对第三级旋风分离器进行改造,采用PSC-300型旋分单管,烟气轮机入口催化剂细粉粒度小于10μm的质量浓度达到92.5 mg/m3,满足烟气轮机设计要求.本周期,烟气轮机运行近3 a以来,烟气轮机解体3次均未发现硬垢,自2017年11月预防性维修后,已连续运行457 d,运行状况良好.

Since May 2010,the 2#RFCCU of SINOPEC Wuhan Company has experienced fouling problem of flue gas turbine.Up to now,the turbine had been shut down 21 times caused by fouling.Various adjustments and modifications have been made in order to meet the requirements of long-term operation.This paper summarizes a series of transformation measures to prevent fouling of the flue gas turbine from 2010 to 2016:reducing the concentration of catalyst fines in flue gas at turbine entrance,reducing the adhesion of catalyst,improving the environment of the turbine.It is found that the key reason for fouling is that the design of original VAS-250 third stage cyclone separator does not match the actual working condition.The actual flue gas flow rate was only 77%of the design value.The flue gas linear velocity was low,and the separation efficiency was low.The concentration of catalyst fines at the entrance of flue gas turbine was 156 mg/m3,and the proportion of particles less than 10μm was only 86%which was less than the design requirements.In June 2016,the third stage cyclone separator was revamped and PSC-300 single cyclone separator was adopted.The particle size of catalyst at the entrance of flue gas turbine was less than 10μm and the concentration was 92.5 mg/m3,which met the design requirements of flue gas turbine.In this operation duration,hard scale has not been found in three disintegration of flue gas turbines since they have been operating for nearly three years.After preventive maintenance in November 2017,the flue gas turbine has been running for 457 days continuously and in good condition.