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Time：2025-05-30 11:56:31 Reading volume：
Working principle of the vacuum dehydration oil filter:The vacuum dehydration oil filter is primarily used to remove moisture, gas, and solid impurities from insulating oils, such as transformer oil and lubricating oil, thereby restoring the insulation performance and physical and chemical properties of the oil. Its core principle is to achieve efficient purification by combining vacuum evaporation and precision filtration.
The vacuum oil filter usually includes the following key steps:
1. Primary filtration (coarse filtration)
- The oil first passes through a coarse filter (such as a 20~50μm filter) to remove large particles of impurities (such as metal chips, fibers, etc.) to protect subsequent equipment.
2. Heating stage
- The oil enters the heater (electric heating or steam heating), and the temperature is raised to 50~70℃ (some models can reach 80℃), reducing the viscosity of the oil and improving the dehydration efficiency.
3. Vacuum dehydration and degassing (core link)
- The heated oil enters the vacuum separation tank (vacuum degree is usually -0.08~-0.099 MPa), under the conditions of high vacuum + atomization/thin film evaporation:
- Water evaporation: free water and dissolved water in the oil are rapidly vaporized under low pressure and pumped out by the vacuum pump.
- Gas separation: dissolved air, hydrogen and other gases are precipitated and discharged.
4. Precision filtration (fine filtration)
- The dehydrated oil passes through the fine filter (1~5μm filter element) to remove tiny particles and ensure the cleanliness of the oil (such as NAS 1638 level 6 or higher).
5. Oil return or storage
- The purified oil can be directly injected back into the transformer or stored in the oil storage tank.
- Raoult's Law: The vapor pressure of the liquid surface is related to the temperature. The boiling point of water decreases under vacuum (e.g., at -0.095 MPa, the boiling point of water is about 40°C), making it easier for water to evaporate.
- Atomization/thin film evaporation:
- Atomization: The oil forms fine droplets through a nozzle or a rotary spray device, increasing the evaporation area.
- Thin film evaporation: The oil forms a thin film on the packing or tower plate, which improves the mass transfer efficiency and accelerates the removal of water and gas.
- Henry's Law: The solubility of a gas in a liquid is proportional to the pressure. Under high vacuum, dissolved gases (such as O₂, N₂) precipitate and are pumped away.
- Reduce the viscosity of the oil, improve fluidity, and make it easier to separate water and gas.
- However, excessive temperature (>80℃) may cause oil oxidation and needs to be strictly controlled.
| Components | Functions |
|------|------|
| Coarse filter | Remove large particles and protect subsequent equipment |
| Heater | Increase oil temperature, reduce viscosity, and promote water evaporation |
| Vacuum separation tank | Core component to achieve oil-water-gas separation |
| Atomizer | Increase oil surface area and improve evaporation efficiency |
| Vacuum pump | Vacuum and discharge water vapor and gas |
| Condenser | Condensate water vapor to prevent it from entering the vacuum pump |
| Fine filter | Remove tiny particles to ensure oil cleanliness |
| Oil pump | Provide power to maintain oil circulation |
- Transformer oil treatment: remove moisture and gas, and increase breakdown voltage (up to 70kV or more).
- Lubricating oil regeneration: extend oil life and reduce equipment wear.
- Steam turbine oil purification: prevent oil emulsification and ensure safe operation of the unit.
- Vacuum control: too low (such as >-0.08 MPa) affects the dehydration effect, and too high may cause oil boiling and splashing.
- Temperature control: generally not exceeding 70℃ to avoid oil oxidation.
- Filter element maintenance: Regularly ｒｅｐｌａｃｅ the fine filter element to prevent clogging.
- Explosion-proof requirements: When handling flammable oil, the equipment must meet explosion-proof standards.
The vacuum dehydration oil filter efficiently removes water, gas and impurities in the oil through a combination of heating + vacuum evaporation + precision filtration. It is a key purification equipment in the power, petrochemical and other industries.
