超临界机组水冷壁高温腐蚀研究

Research on High Temperature Corrosion of Water Wall Tube Used in Supercritical Unit

针对某超临界机组水冷壁管的腐蚀问题进行了相关的背景资料调查和取样实验室检测分析。主要实验内容包括管样金相分析、硬度检测、腐蚀区域及腐蚀产物扫描电镜观察以及X射线能谱分析等。结果表明,该水冷壁管的腐蚀原因为高温S腐蚀。这是由于在燃烧状况不理想的情况下形成了还原性气氛,未被完全燃烧氧化的游离态硫与水冷壁管中的铁反应生成硫化物,破坏了氧化层对管壁的保护作用,造成了管壁的严重高温硫腐蚀。

The relevant background information and sampling laboratory analysis were done for the corrosion problems of water wall tube in a supercritical power unit. The main experimental contents consisted of metallographic analysis, hardness testing, scanning electron microscope observation of corrosion zone and corrosion product and X-ray energy spectrum analysis. The results show that the corrosion reason for the water wall tube is high temperature sulfur corrosion. The unsatisfactory combustion situation results in the reductive atmosphere. The incompletely combustion free state sulfur can react with iron element in the water wall tube ,then, the iron sulfide forms, which can destroy the protection effect of oxide layer on the tube wall, finally, it results in the serious high temperature sulfur corrosion.