300MW机组回油滤网堵塞导致主油箱油位下降原因分析及处理

Reason Analysis on Decline of Main Oil Tank Level Caused by Blockage of Returned Oil Strainer of 300 MW Unit and Its Treatment

某厂一300 MW机组,在开机过程中发现主油箱油位持续下降,但润滑油压、各轴系温度未见异常,检查发现主油箱回油滤网部分堵塞,导致脏油室回油不畅使油位高于主油箱溢流口,部分回油经该溢流口排至事故油坑,而现有油位计因接于回油滤网后,仅能反映净油室油位而不能反映脏油室油位。因此决定在现有油位计旁增设一玻璃管油位计,连接于回油滤筒底部,用于反映脏油室油位,通过两油位(即脏油室、净油室油位)差即可判断回油滤网是否脏污,避免因回油不畅,脏油室油位过高而从溢流口跑油,危急机组安全,甚至发生汽轮机断油烧瓦之类的恶性事件。

The main oil tank level of 300 MW unit is found decreasing continuously during the starting up in a power plant, but is found no abnormality in the lubrication pressure and the temperature of various shafting. Through the inspection, it is found that the returned oil strainer of main oil tank is blocked, resulting in the unsmooth returned oil in the dirty oil tank, which causes the oil level higher than the overflow vent of main oil tank, through which some returned oil is discharged to the accidental oil pit. After a further inspection, it is found that the existing oil level indicator can only reflect the oil level of purified oil but can not reflect that of dirty oil because it is connected with the back of the returned oil strainer. Therefore, it is decided to add a glass tube oil level indicator next to the existing oil level indicator. The new oil level indicator is connected at the bot- tom of returned oil filtering cartridge, which is used to reflect the oil level of dirty oil. Whether the returned oil strainer is dirty can be judged through the difference between the two oil levels （the oil level of dirty oil and purified oil）, which can avoid the oil leakage from the overflow vent when the dirty oil level is over high caused by the unsmooth returned oil to endanger the security of the unit, and the accident of oil cut - off and burn - out of bearing shoe in steam turbine.