蒸汽发生器上升管根部腐蚀开裂可靠性研究

Reliability Study on Corrosion Cracking at the Root of Steam Generator Riser Tube

通过腐蚀形貌和流场结构分析,对某石化企业蒸汽发生器的浮头式换热器上升管管口附近腐蚀、开裂案例进行了成因研究.通过强度校核和失效压力计算分析了该压力容器运行可靠性.两相流冲击腐蚀是该腐蚀、开裂缺陷形成的主要原因;焊接热输入量过大导致的焊缝耐蚀性能下降对腐蚀、开裂有重要影响.经计算,该筒体失效压力为1.58 MPa;强度校核结果表明,该换热器已不满足在设计压力下安全运行的条件.对存在相变传热且没有汽水分界面的换热器,热源介质采用底进顶出结构可削弱两相流腐蚀.

Through the analysis of corrosion morphology and flow field structure,the study was conducted on the causes of corrosion and cracking near the riser nozzle of a floating head heat exchanger in the petrochemical enterprise s steam generator.The operational reliability of the pressure vessel was analyzed through strength verification and failure pressure calculation.The impact corrosion of two-phase flow is the main reason for the formation of corrosion and cracking defects;The decrease in corrosion resistance of welds caused by excessive welding heat input has a significant impact on corrosion and cracking.After calculation,the failure pressure of the cylinder is 1.58 MPa;The strength verification results indicate that the heat exchanger no longer meets the conditions for safe operation under the design pressure.For heat exchangers with phase change heat transfer and no steam water interface,using a bottom in and top out structure as the heat source medium can weaken two-phase flow corrosion.