超临界汽轮机组剩余汽流力的数值模拟研究

Numerical Simulation of Residual Steam Force in Supercritical Steam Turbine

超临界汽轮机组由于其高参数,在部分进汽时会产生很大的剩余汽流力,相对以往亚临界机组,这个力对机组的稳定运行带来了很大的影响。以某电厂660MW典型超临界机组为基础,利用CDF技术,建立了喷嘴-动叶单流道模型,详细计算了不同工况、不同阀序下,作用于轴系的剩余汽流力的大小与方向;分析了不同阀序下汽流力对轴系稳定性的影响:剩余汽流力可改变轴系在轴承内的稳定位置,从而改变轴承的动力特性,使轴系稳定性发生变化,这样的变化可能会引起转子振动增大甚至失稳事故。某电厂实例说明,剩余汽流力在某些阀序下引起轴承载荷变轻,使得轴系振动增大,而改变阀序在一定程度上可以利用剩余汽流力增加轴系稳定性,抑制这种振动。所做的工作可以为电厂消除进汽方式引起的振动提供参考。

Supercritical steam turbines will bring a large residual steam force under partial admission due to its highparameter. The residual steam force is much bigger than which caused in Subcritical turbines and it has greatly affected the stability of the units. The author used CFD to establish the single flow passage model of governing stage that based on typical 660MW supercritieal unit, calculated the residual steam force in different working conditions and different valve orders; The author has analyzed the influence of steam force on the stability of shafting system： The residual steam force can change the position of shafting in the bearing so that it also changed the dynamic characteristics of the bearing. The changes of shafting stability may cause the vibration of rotor and even instability accident. According to the example of the power plants, the residual steam force could reduce bearing load, which will cause vibration of shafting. Changing valve order could use steam force to increase stability and suppress vibration. The work done in this paper may provide reference for suppress the vibration that caused by partial admission.