某超临界600MW机组锅炉水冷壁管泄漏原因分析

Leakage Cause Analysis on Water Wall Tube of a Supercritical 600MW Unit Boiler

某电厂超临界600MW机组锅炉水冷壁管在运行过程中发生泄漏。通过宏观检查、内壁垢量测定、化学成分分析、金相检验、扫描电镜及能谱分析、力学性能试验、硬度测试等方法对水冷壁管的泄漏原因进行了分析。结果表明:水冷壁管内壁垢层较厚且分布不均匀,锅炉燃烧不稳定,导致水冷壁管的外壁出现腐蚀性热疲劳裂纹,内壁出现热疲劳裂纹,最终导致其发生泄漏失效。

The water wall tube of a supercritical 600 MW unit boiler in a power plant leaked during operation.The leakage causes of water wall tube were analyzed by macroscopic examination,inner wall scale measurement,chemical composition analysis,metallographic examination,scanning electron microscope and energy disperse spectroscopy analysis,mechanical property test and hardness test.The results show that the scaling layer on the inner wall of the water wall tube was thick and distributed unevenly,and the combustion of the boiler was not stable,which resulted in corrosive thermal fatigue cracks on the outer wall and thermal fatigue cracks on the inner wall of the water wall tube,and finally led to leakage failure.