汽轮机轴承载荷变化对轴系稳定性的影响

Influence of Bearing Load Variation of Steam Turbine on Shafting Stability

汽轮发电机组经长周期运行后,基础的不均匀沉降和运行过程中参数的调整等,都会引起各轴承座载荷发生变化。其中,高中压转子由于其质量轻,对轴承的载荷非常敏感,载荷不足容易诱发轴承产生自激振动,因此阐明发生自激振动过程中轴承载荷的变化过程很有必要。基于热传递理论,以全周进汽和喷嘴配汽两种配汽方式机组为分析案例,根据支撑轴承金属温度的变化情况进行诊断,达到准确识别轴承载荷不足诱发的自激振动的目的。结果分析表明,轴承的稳定性裕度不足是引起机组发生自激振动故障的主要原因,发生自激振动后轴承金属温度与振动呈相关性,金属温度降低,振动变大。基于热传递理论的诊断方法简单可靠,对汽轮发电机组自激振动的诊断具有重要的参考价值。

After a long period of operation of the steam turbine generator unit,the uneven settlement of the foundation and the adjustment of parameters during operation will cause changes in the load of each bearing pedestal.The high and intermediate pressure rotor is very sensitive to the load of the bearing due to its light weight.If the load is insufficient,it will easily cause self-excited vibration of the bearing.Therefore,it is necessary to clarify the change process of the bearing load during self-excited vibration.Based on the theory of heat transfer,the unit with two steam distribution modes,full cycle steam admission and nozzle steam distribution,is taken as the analysis case,and diagnosis is made according to the change of metal temperature of the support bearing,so as to accurately identify the self-excited vibration caused by insufficient bearing load.The analysis results show that the lack of stability margin of the bearing is the main cause of self-excited vibration failure of the unit.After self-excited vibration,the metal temperature of the bearing is related to the vibration.The metal temperature decreases and the vibration becomes larger.The diagnosis method based on heat transfer theory is simple and reliable,and has important guiding significance for the diagnosis of self-excited vibration of steam turbine generator units.