600MW超临界机组汽轮机低压转子末级叶片损坏原因分析

Damage analysis of the last stage blades of low-pressure rotor of steam turbine about 600 MW super critical units

介绍某发电厂发生的一起超临界机组低压转子末级叶片损坏事故,宏观检查发现是因为反向第6级蜂窝汽封跌落引起的。进一步开展材质分析、力学性能试验、金相试验,并对蜂窝汽封的加工工艺综合分析,得出如下结论:钎焊工艺影响了汽封体的原始热处理状态,使汽封体的综合机械性能下降,而且汽封体结构不合理,加上运行蒸汽的冲击,导致汽封体跌落断裂,造成末级叶片损坏。分析结论对汽轮机的检修、改造具有指导意义。

The falling of reverse 6th honeycomb seals damaged some last stage blades of low-pressure rotor of super critical unit in a power plant. By macroscopical checking, material analysis, mechanical properties testing, metallography testing and the comprehensive analysis of the processing technic of the honeycomb steam seal, it could be deduced that brazing procedure affected the original heat treatment conditions of the honeycomb seal, which led to the mechanical performance reduced. And the seal structure is unreasonable; operating at high temperature high-pressure steam environment accelerated the seals falling. The falling seals struke the last stage blades of low-pressure rotor and resulted in the last stage blades damaged. The analysis result has directive significance for maintenance and retrofit to steam turbine.