火力发电厂高压加热器换热管腐蚀泄漏原因

摘要

某电厂660MW机组高压加热器的换热管材质为TP304奥氏体不锈钢管,机组投运不到半年,该机组的三台高压加热器就分别出现了不同程度的泄漏.通过检测换热管材料的元素组成、力学性能和抗晶间腐蚀性能,排除腐蚀开裂是材料性能不达标造成的可能性.通过对材料表面的EDS分析和腐蚀开裂面的SEM分析,确定高压加热器短期腐蚀开裂的主要原因是在高压加热器汽侧高温高压条件下,侵蚀性介质氯离子在设备运行振动作用下,促进换热管快速发生腐蚀疲劳开裂.%The high-pressure heater tubes of a 660MW thermal power plant are made of TP304 austenitic stainless steel.After half year operation,the different degree of leakage of three high pressure heaters occurred.By testing of chemical composition,mechanical properties and intergranular corrosion of high-pressure heater materials,it is shown that the corrosion cracking was not caused by unqualified material.The results of EDS of tube surface and SEM of cracking surface reveal that corrosion fatigue caused leakage of high-pressure heater tubes,due to the high concentration of Cl-in vapor and vibration of equipment during operation.