How to filter water from turbine oil?

Filtering water from turbine oil requires choosing the appropriate method based on the water content (free water, emulsified water or dissolved water) and oil characteristics. The following are professional solutions:

1. Determine the water type (the first key step)

- Free water: After standing, the oil will separate into layers, and obvious water droplets can be seen at the bottom.

- Emulsified water: The oil is turbid and becomes milky white after shaking (water particle size <1μm).

- Dissolved water: Transparent, but the water content exceeds the standard (the limit of dissolved water in turbine oil is about 50- 100 ppm).

2. Recommended treatment process

(1) High water content (free water > 0.1%)

- Centrifugal separation method

- Use a high-speed centrifuge (≥ 8000 rpm) to directly separate water by density difference.

- Advantages: Large processing capacity (up to 5000L/h), suitable for initial dehydration.

- Note: Trace amounts of emulsified water may remain (secondary treatment is required).

- Gravity sedimentation + vacuum pumping

- Let stand for 24-48 hours to drain the free water at the bottom, and transfer the remaining oil to the vacuum oil filter.

(2) Emulsified water or trace water (<0.1%)

- Vacuum oil filter (preferred)

- Process parameters:

- Temperature: 60-65℃ (avoid oxidation)

- Vacuum degree: ≤50Pa (absolute pressure)

- After treatment, it can be reduced to ≤ 10 ppm (meet ISO 4406 grade requirements).

- Applicable oils: turbine oil (such as ISO VG32/46), transformer oil.

- Coalescing separation oil filter

- Small water droplets are merged into large droplets through the coalescing filter element, and then drained through the hydrophobic separation layer.

- Advantages: No heating, suitable for synthetic ester turbine oils that are afraid of high temperature oxidation.

(3) Extremely small amount of dissolved water (<50ppm)

- Molecular sieve adsorption

- Use 3Å molecular sieve (pore size 0.3nm) to selectively adsorb water.

- Note: The adsorbent needs to be replaced or regenerated regularly.

3. Turbine oil dehydration standard

- ISO 4406 cleanliness: It is recommended to reach ≤15/12/10 (particulate matter)

- Water content:

- Conventional turbine oil: ≤100ppm (GB/T 11120)

- High-pressure steam turbine: ≤50ppm (ASTM D4378)

4. Operation precautions

- Avoid high temperature oxidation: Heating temperature ≤70℃, can be reduced to 50℃ under vacuum environment.

- System circulation filtration: During online filtration, it is necessary to ensure that the oil is circulated 3-5 times (adjusted according to the water content).

- Use demulsifiers with caution: It may change the chemical properties of the oil, and compatibility testing must be done first.

5. Maintenance recommendations

- Daily monitoring: Use a Karl Fischer titrator (accuracy ±1ppm) or an online humidity sensor.

- Equipment selection reference:

- Small flow (<100L/min): ｓｅｌｅｃｔ a desktop vacuum oil filter (such as Pall or CJC models).

- Large flow industrial system: ｓｅｌｅｃｔ a centrifugal + vacuum combination system (such as Alfa Laval solution).

Turbine oil dehydration needs to be combined with the water form to ｓｅｌｅｃｔ the process. The vacuum oil filter is a general and efficient solution. The centrifugal method is suitable for large-scale drainage in the initial stage, and the coalescence type is suitable for emulsified water. After treatment, the moisture content and particle size need to be verified to ensure that they meet the equipment manufacturer's standards (such as Siemens, GE, etc. have special requirements).