汽轮机湿汽损失的分析与研究

对某台抽汽凝汽式机组末级叶片的水蚀特征进行了分析，提出了利用原有准则计算湿汽损失是有缺陷的．指出湿汽损失应该由2个部分组成：一是来源于一次水滴损失，二是来源于二次水滴损失，并且当蒸汽湿度大于一定值时，二次水滴损失应该大于一次水滴损失．同时，阐述了有核凝结形成的一次水滴也会对叶片产生水蚀作用．通过使用汽轮机外缘内表面去湿隔板可以减小湿汽损失，提高机组效率，延长叶片使用寿命．

Analysis and Study on Moisture Loss in Steam Turbines

An analysis has been carried out on water erosion features of the last stage blade in an extraction condensing turbine unit, based on which the original empirical formula for calculation of moisture loss is proved to be insufficient. Moisture loss generally comes from following two aspects the preliminary water droplet and the secondary water droplet. When the steam moisture is higher than a certain value, the loss by secondary water droplet will be greater than that by the preliminary one. Meanwhile, the preliminary water droplet formed by nucleation condensation will also cause water erosion on the blades. The moisture loss may be reduced by using outer-edge inner-surface dewetting boards, with which the unit efficiency will correspondingly be raised and the service life of blades can be elongated.