电站锅炉管件失效泄漏原因分析

火力发电厂管件失效泄漏是频发事故,严重影响机组的安全、经济运行。以某发电厂后墙省煤器和低温再热器管子失效泄漏事故为例,通过对失效泄漏的管件进行宏观形貌分析、金相分析和强度分析,论证了泄漏事故的原因是由于腐蚀和钢管固有缺陷导致低温再热器高温段弯管外侧发生泄漏,泄漏的高速流体冲刷、气蚀导致后隔墙省煤器发生泄漏,进而对低温再热器反冲刷,加剧泄漏事故的恶化。最后提出更换失效管件,加强金属监督,尽量扩大防磨防爆检查范围,对易被气流磨损、冲刷部位进行防磨喷涂或加装防磨罩。

Cause analysis of leakage by tube failure of power station boiler

Tube burst accident of heating surface tubes in a thermal power plant takes place frequently,which seriously affects the safety and economic operation of thermal power plant.In this paper the tube failure leakage accidents of economizer and low temperature reheater in a power plant were analyzed.Three kinds of methods were applied,including macroscopic analysis,metallographic analysis and strength analysis.It showed that overheating was not the cause of this tube burst.Oxygen corrosion and defects of low reheater leaded tube leakage.Then leaking fluid from low temperature reheater tube caused fluid scour and cavitations erosion on the rear wall economizer.Fluid scour and cavitations erosion leaded leakage of the rear wall economizer.The fluid from the rear wall economizer tube caused fluid scour and cavitations erosion on the low reheater which strengthened leakage of low reheater.At last the treatment measure and proposals of preventing similar accident were put forward.The failure tube should be replaced.The examination and test of metal tube should be paid attention to during boiler maintenance.Metal tube which is easy to be scoured should be put on protection covering or coating to prevent from fluid scouring.