某汽轮发电机组复速级第二级动叶片断裂故障分析

Analysis and treatment on blade rupture failure near velocity-compounded stage of steam turbine-generator sets

某汽轮机3片复速级第二级动叶片发生断裂故障,经宏观检查、叶片材料性能分析、有限元分析及疲劳寿命对比分析发现,叶片根部倒圆加工尺寸偏小和叶片材料夹杂物局部偏聚是导致叶片疲劳断裂的主要原因,经提高叶片材料夹杂物等级和叶根倒圆加工精度,重新定做并更换叶片后,机组连续运行结果表明,机组运行正常,故障消除。

A rupture failure was appearred on the second row＇s blade near the vecolity-compounded stage of a steam turbine-genetator sets. After the genearal check, the static stress characteristic, and the material measure characteristic were obtained, the high-frequency fatigue life and the low-frequency fatigue life of the blades were analyzed with contradistinctive calculation. The results of analysis indicated that the fillets＇ process sizes near the hub zone of those blades were too small and the level of the inclusion in these blades＇ meterial were the main reason of the blade rupture. The steam turbine-generator had achieved the repair job through the methods such as the blade replace, enhanced the process precision and the level of the inclusion in these blades＇ meterial. The results of the operatin test shown that the steam tubine-generator sets run normally,libration steadily, and the failure was solved.