加氢装置高压换热器开裂原因分析及对策

文章介绍了某炼油厂加氢裂化装置反应流出物/低分油换热器(E106A)0Cr18Ni10Ti材质管束爆管情况,结合该换热器管、壳程工作条件和防腐措施,利用内窥镜检查、光谱材质分析及硬度性能分析、金相及扫描电镜分析等方法对爆管样品进行了综合分析,并同时采用XRD和能谱对结晶物进行分析。结果表明:E106A换热器管束内壁存在NH₄Cl结晶,当注水量不足时,NH₄Cl水解形成的酸性环境提高了奥氏体不锈钢Cl^-应力腐蚀开裂的敏感性,从而导致该换热器管束发生穿晶型应力腐蚀开裂,当裂纹延伸到一定程度后发生爆管。针对以上腐蚀开裂原因,从工艺控制和设备选材等方面提出了相应的防腐建议和措施。

CAUSE ANALYSIS AND COUNTERMEASURES FOR CRACKING OF HIGH PRESSURE HEAT EXCHANGER IN HYDROGENATION UNIT

This paper introduces the tube burst of 0Cr18Ni10Ti tube bundle of a hydrocracking unit reaction effluent/low separation heat exchanger(E106A)in a refinery.Combined with the working conditions of the tube and shell side of the heat exchanger and the anti-corrosion measures,the tube burst samples are analyzed comprehensively by means of endoscopy,spectral material analysis,hardness performance analysis,metallography and scanning electron microscope analysis.The crystal was analyzed by adopting XRD and energy spectrum.The results show that there is NH4Cl crystal in the inner wall of E106A heat exchanger tube bundle.When the amount of water injection is insufficient,the acid environment formed by hydrolysis of ammonium chloride improves the sensitivity of Cl^-stress corrosion cracking of austenitic stainless steel,which leads to transgranular stress corrosion cracking of the tube bundle of E106A heat exchanger.When the crack extends to a certain extent,the tube bursts.In view of the above corrosion cracking reasons,the corresponding anti-corrosion suggestions and measures are put forward from the aspects of process control and equipment material selection.