How to purify transformer waste oil？

To purify transformer waste oil, several methods can be employed, including physical and chemical treatments. Here's a detailed guide on how to purify transformer waste oil:

Physical Treatment Methods

1. Mechanical Filtration:

   • This method removes solid particles and some suspended impurities from the oil.
   • It is important to use dry filter media and to ｒｅｐｌａｃｅ filter paper when the oil pressure increases or the water content or breakdown voltage of the filtered oil decreases.

2. Centrifugal Separation:

   • Centrifugal separators are used to remove water, solid particles, and oil sludge from transformer oil.
   • They operate at high speeds (above 5000 rpm) to separate contaminants from the oil.
   • However, this method cannot remove dissolved water in the oil and is best used as a preliminary treatment for transformer oil with high concentrations of contaminants.

3. Vacuum Filtration:

   • Vacuum filtration is effective for removing dissolved gases, water, and other impurities from transformer oil.
   • Cold mechanical filtration is good for removing oil sludge and free water, while hot vacuum treatment is better for removing dissolved water and suspended water.
   • The oil temperature should be controlled below 70°C to prevent oxidation.
   • When treating transformer oil with a high water or solid content, centrifugal separation or mechanical filtration should be used before vacuum treatment to improve purification efficiency.

Chemical Treatment Methods

1. Phosphating:

   • This involves adding a phosphating agent to the transformer oil to neutralize acidic substances and improve oil quality.

2. Deacidification:

   • Alkaline substances such as sodium hydroxide or potassium hydroxide are used to neutralize acidic substances in the oil, forming salts that are soluble in the oil.

3. Regeneration:

   • Advanced treatment methods such as adsorption, chemical regeneration, and water washing regeneration can be used to further purify transformer oil.
   • Adsorption methods use adsorbents like activated clay or silica gel to remove impurities.
   • Chemical regeneration involves using sulfuric acid or alkaline solutions to react with oxides in the oil and then removing the resulting residues.

Additional Considerations

1. Regular Monitoring:

   • Regularly sample and test transformer oil to monitor its contamination level and performance.

2. Equipment Selection:

   • Choose appropriate purification equipment and methods based on the transformer's model and operating environment.

3. Operation Standards:

   • Follow strict operating procedures during purification to avoid deteriorating oil quality.

4. Record Keeping:

   • Maintain detailed records of the purification process and results to provide a reference for future maintenance.

By following these methods and considerations, transformer waste oil can be effectively purified, allowing for its reuse and reducing environmental impact.