采用宏微观分析、力学性能试验、化学成分分析、金相检验以及能谱、X射线衍射分析等方法, 对某锅炉SNCR脱硝水冷壁管泄漏原因进行了分析。结果表明: 该水冷壁管泄漏系在尿素腐蚀介质作用下产生的局部腐蚀穿孔所致;从脱硝喷枪泄漏的尿素液滴滴落在高温水冷壁管上和水冷壁管鳍片焊趾处的拉应力分别为水冷壁管的腐蚀泄漏提供了介质条件、温度条件和应力条件。

The leakage reasons of the water-wall tube used for a boiler’s SNCR denitrification were investigated by means of macroscopic and microscopic analysis, mechanical properties test, chemical compositions analysis, metallographic examination, energy disperse spectroscopy analysis and X-ray diffraction analysis. The results indicate that the leakage of the denitrification water-wall tube was caused by the localized corrosive perforation under the corrosive medium of carbamide. The carbamide liquid leaked from the denitrification spaying gun dropping on the high-temperature water-wall tube and the tensile stress at weld toe of the finned tube created the appropriate conditions of medium, temperature and stress for the corrosive leakage.