660 MW汽轮机转子抱死停转原因及处理

Cause Analysis and Treatment of Rotor Locking Stoppage of a 660 MW Steam Turbine

某660 MW机组电厂在#2机组停机后,机组一直未破真空,轴封系统正常投入,在停机5 h后盘车电流波动上涨至最大值,盘车跳闸。机组紧急破真空,联系检修紧急手动盘车,转子抱死,无法盘动。分析原因为机组停运时未及时破真空,轴封压力波动,大量的低温蒸汽通过轴封吸入汽缸,它不仅在转子上引起较大的热应力,而且会造成轴封及轴封处的大轴急剧冷却收缩,收缩量过大时,将有可能导致轴封或汽缸内部动静部分碰磨,进而会导致主机大轴抱死。为此,运行人员提出了一系列改进和优化措施,并在之后的运行中不断摸索完善措施,避免了类似事故的再次发生。

A shutdown,vacuum-maintained,and shaft seal normally operating unit in an actual 660 MW power plant encountered limit reaching of current fluctuation,and further,undesired trip of the turning gear.The unit urgently broke the vacuum and contacted maintenance for emergency manual turning,and found the rotor get locked and could not be turned.The event was analyzed to determine the real causes.The unit was shut down and the vacuum was not broken in a timely manner,resulting in fluctuations in the shaft seal pressure.A large amount of low-temperature steam was sucked into the cylinder through the shaft seal,which not only caused significant thermal stress on the rotor,but also caused rapid cooling and contraction of the shaft seal and large shaft.When the contraction amount was too large,it may cause friction between the shaft seal or the internal dynamic and static parts of the cylinder,leading to main engine shaft locking.The operators proposed a series of improvement and optimization measures,and continuously explored and improved them in subsequent operations,avoiding similar accidents from happening again.