Four supercritical 600 MW units have been installed in one power plant

and two steam-driven feed-water pumps with 50% rated evaporating capacity being equiped for each unit.During operation of said pumps

the phenomenon of sealing water leakage problem has occurred many times

resulting in entrance of water into oil system of the small turbine and the steam-driven pumps

leading to deterioration of oil quality

affecting seriously safe operation of the small turbine and steam-driven pumps.Through rafrofit measures

such as demolishing multi-stage U_shaped tubes of backwater from sealing water

replacing them with water-collecting tank

installing automatic regulating system of water-level in the water tank

reducing flow resistance in the pipeline

adjusting sealing gap of the screw to a small value

and lowering negative pressure in the bearing chamber etc.

the trouble of sealing water leakage from shaft end has been finally eliminated

ensuring normal operation of the units.