660MW超临界直接空冷机组锅炉末级过热器爆管原因分析

Tube-bursting Cause Analysis of Boiler Final Super-heater in 660MW Super Critical Direct Air-cooling Units

为分析660MW超临界锅炉末级过热器爆管原因,对管样进行了宏观形貌、化学成分、显微组织和力学性能分析。结果表明,末级过热器管材各元素含量达标,拉伸及屈服强度合格。爆管的爆口宽大,组织劣化,具有典型的短时严重超温爆管特征。在此基础上,提出了控制启动烟温、加强壁温监控、提高给水品质以及控制温度变化速率等措施,有力保证了锅炉的安全稳定运行。

In order to find the reason for tube-bursting of 660 MW supercritical boiler final superheater, the macro-morphology, chemical composition, microstructure and mechanical properties of the tube were analyzed. The results show that the contents of elements of final superheater pipe meet the requirements of the standards, and the tensile and yield strength are qualified. The burst mouth of the burst tube is wide and its microstructure becomes deteriorate, which shows typical features of short-term serious over-temperature tube-bursting. On this basis, the measures, such as controling the flue start-up gas temperature, strengthening the wall temperature monitoring, improving the quality of water supply and controling temperature change rate and others were put forward, and the safe and stable operation of the boiler was effectively ensured.