汽轮机低压缸轴承座振动分析和动平衡试验研究

Bearing Pedestal Vibration Analysis and Balance Test of a Turbine Low Pressure Rotor with Bearing Located on the Exhaust Cylinder

建立了转子动力学分析时考虑支撑系统刚度后的等效动刚度分析模型,指出等效动刚度随着转速的变化而变化。当工作转速接近支撑系统共振转速时,支撑系统有效动刚度很小,振动对外界激励力敏感,容易发生大幅度轴承座振动。针对某厂600MW汽轮发电机组发生的低压缸轴承座振动故障进行了分析,介绍了机组振动现象、故障原因分析以及在机组上开展的动平衡试验过程。研究结果表明,大型汽轮机座缸式轴承座的振动受支撑特性影响较大,工作转速下运行时容易发生共振现象。这类振动可以通过精细动平衡试验来降低。

An effective dynamic stiffness model considering support system stiffness was set up for rotor dynamic analysis. The effective stiffness changes with rotating speed. It decreases to a low value if the rotating speed is near the support system resonance speed. In the ease, vibration is sensitive to external excitation force and large bearing pedestal vibration is easily to occur. Vibration phenomenon and fault analysis of a low pressure rotor occurred on a 600MW turbine unit was presented. The balance test process was introduced. Test found that the pedestal vibration is influenced by support stiffness largely. Resonance phenomenon is easily to occur near the working speed if the low pressure bearing was designed on the cylinder. The vibration can be reduced by high speed accurate balance in field.