热媒盐换热器换热管腐蚀穿孔失效分析

Failure Analysis of Corrosion Perforation of Tubes in HTS Heat Exchanger

通过外观分析、材料金相组织分析和EDS能谱分析等手段,对某热媒盐换热器换热管腐蚀失效的原因进行了深入分析。结果表明:腐蚀产物中含有硫酸根,这是缓蚀剂磷酸钠中混入了少量的硫酸钠造成的。腐蚀区域集中在换热器的最上部,该部位正是气液两相流界面,锅炉水不断地蒸发波动,造成水中的硫酸根集聚浓缩,局部酸性大大增加,从而引起换热管局部腐蚀。

Based on the analysis of the appearance, material metallographic structure, EDS energy spectrum and other methods, the cause of corrosion failure of the tubes in the heat transport salt （HTS） heat exchanger is deeply analyzed. The result shows that the corrosion products contain the sulfate radical caused by the introduction of the sodium sulfate into the corrosion iuhibitors sodium phosphate. The corrosion area is mainly on the uppermost part of the heat exchanger which is the interface of the gas and the liquid where the sulfate radical assembles and concentrates due to the evaporation of the boiler water that leads to the increase of the local acidity and then the local corrosion of the heat exchange tube.