火电厂锅炉前隔墙省煤器进口联箱短管裂纹分析

Analysis on stub tube cracks of inlet manifold of partition economizer of a power plant

某电厂#3炉前隔墙省煤器进口联箱短管在运行中发生泄漏。割管发现,管内壁有大量明显的横向裂纹。对试样管段进行表面情况检查、金相分析、断口电镜及能谱分析,得出结论:省煤器的破坏为腐蚀性热疲劳,与管系结构、运行方式密切相关。导致热疲劳损坏的原因为交变温度应力,外加机械束缚、介质内压应力。

Leaks happened on tubes of economizer in operation. Cracks were found on part of the cut tubes. After superficial examination, the metallurgy, fracture electron microscope and energy spectrum analyses are made, conclusion of corrosive thermal fatigue closely related to the piping structure and operation mode is reached. The reasons are alternative temperature stress, external mechanical bind and medium internal compression stress, etc. Oil and condenser leaks make the crack corrosive.