Several cracks were found at the end of Ni201 heat exchange tube in a phosgene reactor of a company during shutdown maintenance.In order to explore the causes of the cracks,the cracking of the heat exchange tube was analyzed through macroscopic morphology analysis,on-site metallographic film analysis,combined with the characteristics of the process operation and the special role of the heat exchange tube in the process.The results show that the shape design of the catalyst used in the phosgene reactor is unreasonable,and some of the catalysts slip to the bottom of the heat exchange tube during operation,and the synthesis reaction occurs,resulting in intermittent thermal shock,which leads to cracks in the heat exchange tube due to thermal fatigue.
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