PX装置结晶分离单元常见问题分析与对策

Analysis and countermeasures of common problemsin the crystallization separation unit of PX unit

针对中海石油宁波大榭石化有限公司对二甲苯(PX)装置自投产以来发生结晶器刮刀碎片掉落、管道冻堵、离心机联锁、控制阀失效等多起事故进行了分析,认为是结晶过程不稳定导致生成大量晶块堵塞管道而发生了联锁停机事故。由于外购C_(9)芳烃水含量高,导致结晶装置进料水含量远超工艺要求(进料水质量分数在10μg/g以内),长期运行造成装置内部水分累积。除此之外,还分析了高含水量对结晶过程稳定性的影响以及对装置工艺及设备的危害,并结合装置现状制定对策及合理化建议,有效减少装置波动,确保装置正常生产运行。

In response to the multiple accidents that have occurred in the PX unit of CNOOC Ningbo Daxie Petrochemical Co.,Ltd.since its commissioning,including the falling of crystallizer scraper fragments,pipeline freezing and blockage,centrifuge interlocking,and control valve failure.This article analyzes the common accidents of the unit and summarizes them as the unstable crystallization process leading to the generation of a large number of crystal blocks blocking the pipeline and its interlocking effect.Due to the high water content of purchased C_(9)aromatic hydrocarbons,the feed water content of the crystallization unit far exceeds the process requirements(feed water mass fraction is within 10μg/g),and long-term operation leads to the accumulation of internal water content in the unit.In addition,the impact of high water content on the stability of the crystallization process and its harm to the process and equipment of the unit were analyzed.Based on the current situation of the unit,countermeasures and reasonable suggestions were formulated to effectively reduce device fluctuations and ensure normal production operation of the unit.