Abstract: In this paper, aiming at the problem of seawater leaking into the lubricating oil system and affecting the safe operation of a 1 000-MW unit due to the oil cooler leakage in the coastal area of Shandong Province, the analysis is conducted and the corresponding treatment measure adopting the centrifugal oil filter and the cartridge oil filter to get rid of the water from the oil is proposed. Meanwhile, the dissolving elution method is proposed to determine the chlorine ion content in the oil, which helps to make a judgement on whether the seawater entrained in the oil is cleaned. With the oil filter processing, the moisture content of turbine oil falls from 24 414 mg/L to 10.1 mg/L, while the chloride ion content is from 155 mg/L down to the undetected. The practice proves that the oil filter processing can make the heavily seawater polluted lubricating oil return to normal in a short time, which can ensure the safe operation of the unit and avoid malignant accidents.

Key words: steam turbine, seawater leaking into oil system, cause analysis, treatment, dissolving elution method