备用油浆泵机械密封失效原因及对策

催化热裂解工艺反应温度高、裂解深度大,致使循环油浆中含有较多易结焦积炭的聚合物。苛刻的工作条件降低了油浆泵机械密封的使用性能,并且备用油浆泵时常因机械密封失效而发生泄漏,以至不能正常运行。对备用油浆泵机械密封失效原因进行了分析,调整了备用油浆泵常开机械密封冲洗液的操作方案;为避免因粗柴油冲洗液汽化使运行泵发生汽蚀,改用常压渣油作为机械密封冲洗液,取得了良好的效果。改造后的油浆泵已运行5个月,主、备泵切换累计3次,未更换机械密封,节省了机械密封的备件费用,降低了柴油作为冲洗液所增加的生产成本,未发生过主、备泵机械密封同时大量泄漏的事故,确保了装置长周期稳定运行。

Failure causes of mechanical seal of spare slurry pump and countermeasures

As catalytic pyrolysis cracking process is high in reaction temperature and deep in cracking, the recycle slurry oil contains a higher amount of polymers which are subject to coking. Harsh work conditions have reduced the service life of slurry oil pump＇ s mechanical seal, and spare slurry oil pump often leaked be- cause of mechanical seal failure which affected the normal operation. The causes of mechanical seal failure were analyzed and the operation of flush liquid of mechanical seal of spare slurry pump was adjusted. The at- mospheric residue was used as flush liquid of spare pump＇ s mechanical seal to avoid cavitation of pump when it is flushed by diesel oil, and good results have been achieved. The revamped slurry pump has been operating for 5 months, and operating and spare pumps have been switched over for 3 times. No mechanical seals need to be replaced and costs of spare mechanical seals and additional costs of using diesel oil as flush liquid have been saved. No large leakages of operating and spare pumps have occurred ever since and long-term operation of the unit has been ensured.