关键词: font-family:-apple-system, blinkmacsystemfont, ", font-size:14px, background-color:#FFFFFF, ">PX装置, 结晶分离, 含水量, 结晶器, 管道和阀门, 离心机

Abstract: 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 crystal scraper fragments, pipeline freezing, centrifuge interlocking, and control valve failure, it is analyzed that these are caused by unstable crystallization process leading to the blockage of pipelines by a large number of crystal blocks, resulting in interlocking shutdown accidents. Due to the high water content in the purchased C₉ aromatic hydrocarbons, the water content in the feed to the crystallization unit far exceeds the process requirements (feed water mass fraction within 10 μg/g), and long-term operation leads to the accumulation of water inside the unit. In addition, the impact of high water content on the stability of the crystallization process and the harm to the unit's process and equipment are also analyzed. Countermeasures and rationalization suggestions are formulated based on the current situation of the unit to effectively reduce fluctuations and ensure normal production operation.

Key words: font-family:-apple-system, blinkmacsystemfont, ", font-size:14px, background-color:#FFFFFF, ">PX unit, crystallization separation, water content, crystallizer, pipelines and valves, centrifuge