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Time：2025-06-27 11:52:54 Reading volume：
The main purpose of transformer oil degassing is to remove dissolved gases (such as H₂, O₂, N₂, CO, CH₄, C₂H₂, etc.) and trace amounts of water in the oil to restore the insulation properties and chemical stability of the oil. Common degassing methods include the following:
Principle: Use vacuum negative pressure to reduce the solubility of gas in the oil, so that the gas precipitates from the oil and is pumped away.
Method:
- Heat the oil to 50~70℃ (reduce viscosity and promote gas release).
- In a high vacuum (<1mbar) environment, the oil is dispersed by spraying or film to increase the surface area and accelerate degassing.
Advantages:
- High degassing efficiency, can deeply remove non-fault gases such as O₂ and N₂.
- Suitable for on-site treatment of large transformer oil.
Disadvantages:
- The equipment is complex and requires a stable vacuum system.
- The removal of small molecular gases such as H₂ and CH₄ is slow.
Application:
- Transformer oil regeneration
- Degassing before new oil injection
Principle: Use a selectively permeable membrane (such as polyimide, silicone rubber membrane) to allow the gas in the oil to pass through the membrane and be extracted, while the oil remains in the system.
Method:
- The oil flows through a hollow fiber membrane or a flat membrane assembly, and one side of the membrane is kept in a vacuum or purged with gas (such as N₂).
- The gas passes through the membrane due to the partial pressure difference, and the oil continues to circulate.
Advantages:
- It can be degassed online continuously, which is suitable for the treatment of transformer oil in operation.
- High selectivity for small molecular gases such as H₂ and CO.
Disadvantages:
- The membrane is easily contaminated and requires regular maintenance.
- The investment cost is relatively high.
Application:
- Transformer online monitoring (DGA system matching)
- Special removal of hydrogen (H₂)
Principle: Use the ultrasonic cavitation effect to generate tiny bubbles to promote the precipitation of dissolved gas in the oil.
Method:
- The oil flows through the ultrasonic transducer, and the high-frequency vibration (20~100kHz) causes the gas to gather into bubbles and float up and separate.
- Can be combined with vacuum or nitrogen purge to improve efficiency.
Advantages:
- Simple equipment and low energy consumption.
- Suitable for degassing of small transformers or laboratories.
Disadvantages:
- Poor effect on high-viscosity oil.
- May cause local overheating of the oil.
Application:
- Laboratory oil sample pretreatment
- Auxiliary vacuum degassing
Principle: Introduce high-purity nitrogen (N₂) into the oil, and use gas replacement to reduce the content of O₂, H₂, etc. in the oil.
Method:
- Nitrogen is bubbled in from the bottom of the oil tank to form tiny bubbles and take away the dissolved gas.
- Heating (40~60℃) can be combined to increase the degassing rate.
Advantages:
- Simple operation and low cost.
- It can effectively reduce the oxygen content and delay oil oxidation.
Disadvantages:
- The removal effect of fault gases such as CH₄, C₂H₂ is limited.
- Trace nitrogen residues may be introduced.
Application:
- Deoxygenation treatment before transformer oil filling
- Temporary gas control
Principle: Use adsorbents such as molecular sieves and activated alumina to selectively adsorb gas in oil.
Method:
- The oil flows through the adsorption column, the gas is captured by the adsorbent, and the purified oil returns to the transformer.
- The adsorbent can be heated for regeneration or replacement.
Advantages:
- Specific gases (such as H₂, CO) can be removed in a targeted manner.
- Suitable for small degassing needs.
Disadvantages:
- The adsorbent is easily saturated and requires frequent maintenance.
- It may affect additives in the oil.
Application:
- Online purification of transformer oil
- Used with DGA system
Summary
- Large transformer maintenance → Vacuum degassing (efficient and thorough)
- Online monitoring (DGA) → Membrane degassing (continuous operation)
- Laboratory treatment → Ultrasonic/adsorption method (flexible and simple)
- Temporary deoxidation → Nitrogen bubbling (economical and fast)
The selection of an appropriate degassing method requires comprehensive consideration of gas type, oil volume, cost and operating conditions.
