多支撑汽轮机轴承标高调整对轴封间隙的影响分析

Influence of Elevation Adjustment on Shaft Seal Clearance of a Multi-support Turbo-Generator Unit

采用传递矩阵法、差分法等建立多支撑轴系轴承标高调整对相邻截面轴封间隙影响的分析模型,考虑了轴承标高调整对轴承载荷的影响、轴承载荷对轴颈偏心距和偏位角的影响以及转轴弹性变形等因素的共同作用,并以某大型汽轮发电机组为实例进行了计算分析。结果表明:受油膜、转轴弹性变形等因素影响,轴封间隙变化量小于轴承标高调整量;与中间轴承相比,自由端附近轴封间隙变化对轴承标高变化不敏感;轴承载荷越轻,轴承标高调整对轴封间隙变化的影响越小,对于油膜振荡等失稳类故障,故障治理时标高调整幅度可以大些;低转速下油膜较薄,缓冲效果较弱,轴封间隙变化对轴承标高变化较敏感。

By means of transferring matrix and differential method,an analytical model was established for the influence of elevation adjustment of multi-support shafting bearings on the clearance of adjacent shaft seals,considering the effects of bearing elevation adjustment on the bearing load,the effects of bearing load on both the eccentricity and deflection angle as well as the elastic influence of the shaft,which was subsequently applied to the calculation and analysis of a large scale steam turbine.Results show that the change of seal clearance is mostly less than the adjustment of bearing elevation due to the influence of oil film and elastic deformation of the shaft.Compared with the intermediate bearing,the gap of the shaft seal near free end is not sensitive to the change of bearing elevation.The lower the bearing load,the smaller the influence of elevation adjustment on the clearance change.To deal with an oil-film instability fault,the scope of elevation adjustment could be enlarged.The change of seal clearance is sensitive to that of elevation adjustment at low speeds due to poor damping effect of thin oil film.