一起锅炉烟管腐蚀穿孔事故原因分析

Analysis on the Causes of Corrosion and Perforation Accidents in Boiler Smoke Pipes

某酒店的WNS型燃气锅炉烟管发生了腐蚀穿孔泄漏,向工作人员了解到该锅炉常年在运行与备用交替状态,停炉期间加药泵也持续不断地向炉内加药。对锅炉进行了水质检测分析虽然水质符合标准,但是锅炉依旧有水垢生成;对样管进行了显微组织金相分析显示管材球化2级;对腐蚀产物进行射线能谱仪测试分析,发现腐蚀产物以Fe、O为主,同时存在Si、Ca、Mg、Cl、S、P成分。通过腐蚀机理分析得出该锅炉烟管水侧腐蚀为局部电化学腐蚀,金属腐蚀类型为氧腐蚀和介质浓缩碱腐蚀。给水中过量加药造成介质浓缩碱腐蚀,锅水未进行有效除氧产生氧腐蚀,锅水中Cl^(-)在薄弱的氧化膜上产生小孔腐蚀,钢材中夹杂的硫化物加快了腐蚀速度,从而引发烟管腐蚀穿孔。

The smoke pipe of a WNS type gas boiler in a certain hotel has undergone corosion,perforation,and leakage.It was learned from the staff that the boiler is in an alternating state of operation and standby all year round.During the shutdown period,the dosing pump also continuously adds medicine to the furnace.Water quality testing and analysis were conducted on the boiler.Although the water quality meets the standards,there is still scale generation in the boiler;The microstructure and metallographic analysis of the sample tube showed that the spheroidization of the tube was level 2;The corrosion products were tested and analyzed by X-ray energy spectrometer,and it was found that the corrosion products were mainly composed of Fe and O,with the presence of Si,Ca,Mg,Cl,S,and P components.Through the analysis of corrosion mechanism,it is concluded that the water side corrosion of the boiler flue pipe is localized electrochemical corrosion,and the types of metal corrosion are oxygen corrosion and medium concentrated alkali corrosion.Excessive dosing in water causes concentrated alkaline corrosion of the medium,ineffective deoxygenation of the boiler water results in oxygen corrosion,and Cl^(-) in the boiler water cause small hole corrosion on the weak oxide film.The inclusion of sulfides in the steel accelerates the corrosion rate,leading to corrosion perforation of the smoke pipe.