煤气化变换系统蒸汽过热器列管失效分析及防范措施

针对陕西延长中煤榆林能源化工有限公司甲醇联合装置中煤气化变换系统蒸汽过热器列管失效的问题,采用金相组织、化学分析、扫描电镜及能谱实验进行了原因分析。结果表明,换热器列管表面存在大量由于氯离子腐蚀形成的点蚀坑,在温度和环向应力的共同作用下,引起应力腐蚀开裂,最终导致换热器列管失效。并围绕腐蚀介质和应力两个因素,从设备选型、设备加工、工艺指标等方面提出了防范措施。

Analysis of Steam Superheater Tube Failure in Coal Gas Conversion System and Its Countermeasure

In view of the tube failure of the steam superheater of the coal gasification conversion system in the methanol combined unit of Shaanxi Yanchang Coal Yulin Energy and Chemical Co.,Ltd.,the metallographic structure,chemical analysis,scanning electron microscope and energy spectrum test were used to analyze the cause.The results showed that there were a large number of pits on the surface of the heat exchanger tubes due to chloride ion corrosion.Under the combined action of temperature and circumferential stress,stress corrosion cracking was caused,which eventually led to the failure of the heat exchanger tubes.Based on the two factors of corrosion medium and stress,the countermeasures were put forward from the aspects of equipment selection,equipment processing and process flow index.