除氧器进汽逆止阀失效暗藏机组跳闸风险

Unit tripping risk analysis hidden behind the failure of deaerator admission check valve

通过对某火电机组一次跳闸事件的分析,从理论上否定了高低压旁路短时误开必然导致机组跳闸的错误说法。结合现场实际进一步分析,确认除氧器进汽逆止阀失效是此次机组跳闸的直接原因。该阀失效后,能在前后压差下开启,但无法起到逆止作用,一旦机组大幅快速减负荷,将会引起给水泵汽轮机水冲击,导致机组跳闸。

By analyzing the tripping of a thermal power unit,it theoretically negates the inevitability of tripping led by short-time high/low voltage bypass fault opening.Combined with the further analysis on site,it is confirmed that the failure of the deaerator admission check valve was the direct cause of the unit tripping.After the valve fails,it can be opened by the front-and-back pressure difference,but it cannot play the role of backstop.Once the unit is greatly reduced in load,it will bring water shock to the water pump turbine,which causes the unit tripping.