论文36030.docVIP

毕业设计（论文） 题 目: 汽轮机排汽湿度对机组运行的影响 2006 年 06 月 18 日 摘 要 在大型火力发电厂中，凝汽式汽轮机的末几级和核电汽轮机的所有级都工作在湿蒸汽区，蒸汽湿度会引起叶片水蚀，叶片水蚀对汽轮机的安全运行构成了威胁，同时水蚀也增加了叶片通流部分的流动损失，导致汽轮机的效率降低，而湿度造成的湿汽损失也降低了汽轮机的效率，所以湿度对汽轮机运行的安全性和经济性有着重要影响。因此对汽轮机排汽湿度进行在线监测具有重要的意义。 在汽轮机排汽焓的计算过程中，由于排汽处于湿蒸汽区，不能由压力或温度单独确定低压缸排汽焓，通过对汽轮机排汽湿度进行在线监测，由此得到的热经济性指标才能够真实地反映出汽轮机的实际运行状态，得出实际的排汽焓及低压缸效率，从而为运行指导及设备的状态检修提供依据。 本文分析了末级排汽湿度对汽轮机经济性及安全性的影响。利用华能大连电厂大量现场实测数据计算出末级排汽湿度及低压缸效率，由湿度与负荷等参数的变化关系来进行经济性分析。湿度对安全性的影响主要是产生叶片水蚀，所以通过叶片的水蚀来分析进行机组的安全性。 湿度对汽轮机的经济性及安全性都有着重大的影响，因此在线湿度监测为现场汽轮机结构设计及维修和汽轮机性能分析提供了参考依据。 关键词： 湿度，汽轮机，经济性，安全性 Abstract In modern thermal power plants, the final several stages in condensate steam turbine and all the stages in nuclear steam turbine operate in wet steam region, the drain erosion on blade is caused by the wetness fraction, the operation safety of steam turbine is threaten by the blade erosion. At the same time, the blade erosion increases the flow losses in flow passage, which decreases the efficiency of steam turbine. Furthermore, the moisture loss decreases the efficiency of steam turbine too. so the wetness fraction have a great influence on the operation of steam turbine about safety and efficiency. Therefore，it is significant for monitoring the wetness fraction on line in exhaust of steam turbine. The enthalpy could not be determined by pressure and temperature due to the exhaust in the wet steam region when we compute the thermal parameters on efficiency, on line monitoring the exhaust wetness fraction is necessary. If the exhaust wetness fraction were monitored, the thermal parameters on efficiency would be credible. Because they show the real operation state on steam turbine, the operation instruction and maintain of equipment is based on the real condition. The influences of wetness fraction on the steam turbine efficiency and the safety are analyzed in this thesis. The wetness fraction is calculated by using the massive measured data of real units of dalian power station, then the relations of the