1000MW二次再热汽轮机轴封系统问题分析及对策

国电泰州3号机组的顺利投产标志着百万千瓦等级二次再热燃煤发电机组正式进入商业运行。机组运行参数优良,但在调试的过程中出现了轴封温度低、机组跳闸后轴封压力低、轴封温度波动大、轴封压力波动大和因轴封蒸汽倒流导致超高压缸排汽温度高等问题。针对这些问题进行了详细分析,认为是由于二次再热排汽温度高、轴封漏气量大、轴封减温水雾化效果差、轴封温度控制逻辑不符合二次再热特点、超高压缸第一级轴封引出管未设计安装逆止门等原因造成,并提出采用轴封电加热器、改善轴封减温水喷嘴、修改轴封温度控制逻辑、增加引出管逆止门等方法加以解决,为今后相同和相似机组的调试运行提供了参考。

Analysis and Treatment of Shaft Sealing Problems in 1 000-MW Double Reheat Turbines

The successful commissioning of Taizhou No.3 unit indicates the start of the commercial operation of the million kilowatt coal- fired generating units with the double reheat system. While the operating parameters appear good, the unit has yet some problems such as low gland seal steam temperature during debugging, low shaft seal steam pressure, large shaft seal steam temperature, pressure fluctuations after tripping, and high VHP exhaust steam temperature due to sealing steam reversed flow. Aiming at these problems, detailed analysis is conducted, which concludes that they are attributed to the high exhaust steam temperature, the large shaft seal steam leakage, the dreadful atomization effect of shaft seal attempering water, the shaft seal steam temperature control logics inconsistency with the double reheat system and the lack of check valve on the outlet pipe from the first shaft seal of the VHP cylinder. Following the analysis, corresponding solutions are put forward, including installing electric heaters, improving the atomization nozzle, modifying the temperature control logics and equipping check valves, hoping to help better operating the same and similar units in the future.