600MW汽轮机低压缸末级叶片的强度分析

The Strength Analysis of 600MW Steam Turbine Low-pressure Cylinder Last Blade

汽轮机运行过程中,低压缸末级长叶片高速旋转,承受了较大的离心力以及蒸汽参数变化产生的交变应力,导致低压缸转动部件产生裂纹,危及机组的安全运行。通过对低压缸末级叶片进行三维建模和低压缸转子进行二维建模,分析惯性载荷以及蒸汽温度变化对转子强度的影响。结果表明:机组启动过程中,当转速增加时叶片与轮缘的等效应力随之增大,最大受力点的等效应力变化规律与转速上升曲线基本一致;汽轮机冷态启动初期,温度载荷对结构应力的影响最大,随着启动时间的增加,转子温度呈级间分布,其影响逐渐减弱。

During the operation of the steam turbine,the long blades rotate at a high speed at the end of the low-pressure cylinder,which bears large centrifugal force and alternating stress caused by the change of steam parameters,leading to cracks in the rotating parts of the low-pressure cylinder and endangering the safe operation of the unit.The three-dimensional model of the long blades at the end of the low-pressure cylinder and the two-dimensional model of the low-pressure cylinder rotor are carried out respectively to analyze the effects of inertial load and steam temperature changing on the rotor strength.The results show that during the start-up of the unit,the equivalent stress of the blade and the flange increases with the increase of rotating speed,and the change rule of the equivalent stress at the maximum stress point is basically consistent with the speed-up curve.At the beginning of the cold start-up,the temperature load has the greatest influence on the structural stress.With the increase of start-up time,the temperature of the rotor is distributed between stages,and the effect of the temperature load gradually weakens.