【摘要】 【目的】旨在分析某660 MW超超临界锅炉运行过程中水冷壁发生爆管泄漏原因。【方法】结合锅炉运行工况，利用宏观分析、化学成分检测、显微组织分析、断口形貌观察及力学性能测试等方法对水冷壁泄漏原因展开分析。【结果】结果表明，锅炉螺旋水冷壁管对接焊缝焊接工艺及操作不当，造成焊缝形成淬硬组织和淬火冷裂纹，并积聚了较高水平的残余应力。在机组的频繁大幅度、快速负荷变化的灵活性工况下长期运行过程中，在焊接残余应力及炉膛的复杂、高水平的膨胀应力叠加作用下，对接焊缝中的淬火裂纹快速扩展并贯穿焊缝，最终导致泄漏，并因介质流量及换热能力严重不足，引发同管路的出口垂直段水冷壁管内发生短时过热爆管泄漏。【结论】在灵活性运行工况下，660 MW超超临界锅炉水冷壁发生泄漏主要是由于焊接工艺及操作不当和机组负荷变化剧烈的原因。更多还原

【Abstract】 [Objective] The aim is to analyze the causes of tube bursting and leakage in the water wall during the operation of a 660 MW ultra supercritical boiler. [Methods] Combined with the boiler operation conditions, the cause of water wall leakage is analyzed using methods such as macroscopic analysis, chemical composition detection, microstructure analysis, obervision of fracture morphology and mechanical performance testing. [Results] The results show that improper welding process and operation of the butt weld of the spiral water wall tubes result in the formation of hardened microstructure and quenching cold cracks in the weld, as well as the accumulation of high levels of residual stress. During the long-term operation of the unit under the flexible working conditions of frequent large fluctuations and rapid load changes,under the combined effect of welding residual stress and the complex and high-level expansion stress of the furnace, quenching cracks of the butt weld rapidly expand and penetrate the weld, ultimately leading to leakage, and causing tubes burst and leakage when short term overheating in the outlet vertical segment of the water wall tube at the same piping system due to severe insufficient medium flow rate and heat exchange capacity. [Conclusion] Under flexible operating conditions, water wall leakage of 660 MW ultra supercritical boiler mostly dues to the improper welding process and operation and dramatically changes of unit load.更多还原