大型轴流风机油泵切换低油压现象的分析及改造

Analysis and elimination of low oil pressure phenomenon while switching oilpumps of large axial-flow fans

珠海发电厂700MW机组原送、引风机油系统运行油泵切换到备用油泵时常常出现低油压现象,备用泵起不到可靠的备用作用。为此对此现象进行了分析,其原因是:油泵的叶片有磨损,泵的出力下降;油泵切换周期偏长,备用泵起动时干涩,响声较大。为此,制定了改造措施:出口排气阀的位置往泵体方向移近;油泵出口自动排空气管由原来在油箱液面上改到液面下面,保证备用泵进出口管道充满油;在两台油泵的入口增加了两个联络门。改造后,油泵起动平稳无异响,出口压力稳定。

The original oil system for blast and draft fans of 700 MW units in Zhuhai Power Station often experienced low oil pressure while switching the operation oil pump to stand-by oil pump,and the stand-by pump could not work reliably.Upon analysis on the phenomenon, a conclusion is drawn that the phenomenon was caused by decrease in the output of the pumps with attrited blades and by long switching interval of oil pumps that led to unsmoothness and loud noise when starting the stand-by pump.Consequently,the outlet exhaust valve was moved closer to the pump, the outlet automatic exhaust pipe was placed under oil level of the oil tank to ensure that the inlet and outlet pipes of the stand-by pump are full of oil,and two communication valves were added to the inlets of the two oil pumps.After the above reconstruction,the start-up of the oil pumps are stable without abnormal noise and the outlet pressure is steady.