循环流化床锅炉水冷壁管泄漏原因探讨

Study on Leakage Causes of Water Wall Tube of Circulating Fluidized Bed Boiler

某电厂1号锅炉在整套启动运行过程中发生了水冷壁管泄漏,为了查明泄漏原因,利用宏观形貌分析、化学成分分析、金相组织检测及力学性能测试等方法,对泄漏的水冷壁管进行了综合性试验分析。结果表明,1号锅炉水冷壁泄漏的主要原因为水冷壁管对接焊缝内存在结晶裂纹(热裂纹),在锅炉启停以及负荷变化过程中的管排膨胀收缩应力及内部介质压力的叠加作用下,焊缝中细小的结晶裂纹扩展贯穿焊缝而引起泄漏。针对1号锅炉水冷壁管泄漏的原因,提出了有效的预防措施,以防止同类泄漏事故的再次发生,保证机组的安全、稳定、连续运行。

A water wall tube leakage occurred in No.1 boiler of a power plant during the whole starting and running process.In order to find out the cause of the leakage,a comprehensive test analysis was carried out on the leaking water wall tube by means of macroscopic feature analysis,chemical composition analysis,metallographic structure test and mechanical property test.The results show that the main reason for the leakage of the water wall of No.1 boiler is that there are crystal cracks(thermal cracks)in the butt weld of the water wall tube.Under the superposition of the expansion and contraction stress of the tube rows and internal medium pressure during the process of boiler start-up and stopping and load change,the fine crystal cracks in the weld expand through the weld and cause leakage.According to the cause of leakage of water wall tube of No.1 boiler,effective preventive measures are put forward to prevent similar leakage accidents from happening again and ensure the safe,stable and continuous operation of the unit.