超临界对冲燃烧式机组水冷壁高温区腐蚀原因分析

Analysis of Corrosion of High-temperature Region of Water-cooled Wall of Hedge Combustion Supercritical Unit

针对某国产600 MW超临界锅炉长周期运行后高温区侧墙螺旋水冷壁腐蚀情况,利用电镜能谱、X射线荧光光谱、物相分析对水冷壁管外壁附着物进行分析。分析结果表明:水冷壁外壁附着物包含大量FeS,硫元素质量百分比平均在26.7%。水冷壁管的金相组织为铁素体加珠光体,烟气侧硫化物型高温腐蚀是导致水冷壁管腐蚀减薄的直接原因。建议通过防腐喷涂、燃烧调整、贴壁风改造等措施防止水冷壁高温腐蚀减薄。

After a long period of operation of a domestic 600 MW supercritical boiler,the analysis of the corrosion of the spiral water cooling wall of the side wall in the high temperature zone.The analysis of the attachments on the outer wall of the water-cooled wall tube using mirror energy spectroscopy,X-ray fluorescence spectroscopy,and phase analysis,showed that the attachments on the outer wall of the water-cooled wall contain a large amount of FeS,and the sulfur element mass percentage averages 26.7%.The metallographic structure of the water-walled tube is ferrite plus pearlite,and the high-temperature corrosion of the sulfide on the flue gas side does not affect the internal structure of the metal.The high temperature corrosion of sulfide on the flue gas side is the direct cause of the corrosion thinning of the water-cooled wall pipe.The higher sulfur content in coal combustion is the root cause of the high temperature corrosion of sulfide.It can be solved by anti-corrosion spraying,combustion adjustment and walling air modification to reduce water wall corrosion at high temperature.