600 MW超临界火电机组低低温省煤器管失效分析  

Failure analysis of low-low temperature economizer pipe in 600 MW super-critical thermal power unit

作　　者：陈志荣 房璐璐 王鲁 CHEN Zhirong;FANG Lulu;WANG Lu(Huadian Electric Power Research Institute Co.,Ltd.,Hangzhou 310030,China)

机构地区：[1]华电电力科学研究院有限公司,杭州310030

出　　处：《黑龙江电力》2020年第5期447-452,共6页Heilongjiang Electric Power

摘　　要：为分析某电厂600 MW超临界火电机组低低温省煤器泄露管道的失效类型及机理,采用宏观形貌检查、基体化学成分分析、金相检验、扫描电镜及X射线衍射检测方法,结合低低温省煤器现场泄漏情况对泄露样管进行深入研究。结果表明,发生泄漏的低低温省煤器管段表面积灰情况严重,可见多处宏观泄漏点,样管外壁大面积呈现凹凸不平,宏观形貌具有明显的低温腐蚀特征;样管的化学成分完全符合国家标准或行业标准对ND钢的要求;金相显微组织为铁素体加珠光体加碳化物,显微组织中可观察到孔洞及沿晶微裂纹;样管外壁泄漏点及凹坑内腐蚀产物主要由Fe、Cu、Cr、Sb元素的硫化物及氧化物构成。综合判断,低温腐蚀是造成低低温省煤器管道泄漏的主要原因。In order to analyze the failure type and mechanism of low-low temperature economizer leakage pipe in a 600 MW super-critical thermal power unit,the methods of macroscopic morphology inspection,chemical composition analysis of matrix,metallographic examination,scanning electron microscope and X-ray diffraction are used to conduct in-depth study on the leakage sample pipe combined with the on-set leakage situation of the low-low temperature economizer.The results show that serious ash accumulation and macroscopic leakage points are occurred on the surface of the low-low temperature economizer leakage pipe.The outer surface of the sample pipe shows a large area of unevenness,and macroscopic morphology has obvious low-temperature corrosion characteristics.The chemical composition of the sample pipe fully meets the requirements of national standards or industry standards for ND steel.The metallographic microstructure is composed of ferrite,pearlite and carbide,and holes and intergranular micro-cracks could be observed.The corrosion products in the pits and leakage points of the outer surface of the sample pipe are mainly composed of sulfides and oxides of Fe,Cu,Cr and Sb.It can be concluded that low temperature corrosion is the main cause of low-low temperature economizer pipe leakage.

关 键 词：燃煤锅炉 低低温省煤器 低温腐蚀 ND钢 失效分析 

分 类 号：TK223.33[动力工程及工程热物理—动力机械及工程]