伯德曲线在某300 MW汽轮机高中压转子裂纹故障诊断中的应用

Application of abnormal Bode curve in crack diagnosis of HP-IP rotor of a 300 MW steam turbine

某300MW机组运行中汽轮机高中压转子振动不断爬升,且与主蒸汽压力升高和主蒸汽温度降低密切相关。通过启停机过程异常伯德曲线的分析以及振动与主蒸汽压力升高、温度降低高度敏感的特征,诊断高中压转子振动不断爬升的根本原因是转子出现了较严重的横向裂纹。揭缸检查发现,高中压转子调节级后应力释放槽位置存在长度覆盖超过3/4圆周周长、最深194 mm的横向裂纹,证实了诊断结论的正确性。深度调峰、灵活性运行方式会影响汽轮机转子的疲劳寿命,严重时会导致产生转子裂纹。建议加强对振动特征异常表现,特别是启停机过程异常伯德曲线的分析,及早发现存在裂纹,采取相应处理措施。

The vibration of high-medium pressure rotor of a 300 MW unit turbine kept climbing during the operation,and the vibration was closely related to pressure rise and temperature drop of the main steam.By analyzing the abnormal Byrd curve during start-up and shutdown of the turbine and the highly sensitive characteristics of vibration and main steam pressure rising and temperature decreasing,it is diagnosed that the root cause of vibration climbing of the HP-IP rotor is the severe transverse cracks in the rotor.The inspection results of cylinder removal confirmed the diagnosis conclusion.It is found that,at the position of the stress relief groove after the adjustment of the HP-IP rotor,there existed a transverse crack with length of more than 3/4 of the circumference(the maximum of 194 mm).Deep peak regulation and flexible operation mode would affect the fatigue life of the turbine rotor,and even lead to rotor crack.It suggests that analysis on abnormal performance of the vibration characteristics should be strengthened,especially the abnormal Bode curve of the startup and shutdown process,so as to find out the existence of cracks and take corresponding measures.