Transformer waste oil filtration method

Transformer waste oil filtration and regeneration methods

Transformer waste oil filtration and regeneration are important to power equipment maintenance. The following is a systematic treatment method:

Pretreatment stage

1. Sedimentation separation method

- Natural sedimentation: let stand for more than 72 hours, and use gravity to separate water and impurities

- Heating sedimentation: heat to 60-70℃ to accelerate sedimentation (pay attention to fire prevention)

- Centrifugal sedimentation: Use a centrifuge to quickly separate large particle impurities

2. Coarse filtration treatment

- Metal filter filtration: 100-200 mesh stainless steel filter to remove visible particles

- Filter paper filtration: Use special filter paper for preliminary purification

- Bag filtration: multi-layer fiber bag filter for large particle pollutants

Deep treatment technology

1. Vacuum dehydration and degassing method

- Working principle: treatment at 50-70℃, vacuum degree -0.095～-0.099MPa

- Treatment effect: water content can be reduced to below 10 ppm

- Equipment type:

- Single-stage vacuum oil filter

Double-stage high vacuum oil filter

2. Precision filtration technology

- Filter element type:

- Cellulose filter element (precision 5-10μm)

- Glass fiber filter element (precision 1-3μm)

- Stainless steel sintered filter element (cleanable and reusable)

- Multi-stage filtration system: connect filter elements of different precisions in series to achieve gradient purification

3. Adsorption regeneration method

- Commonly used adsorbents:

- Activated clay (dosage 3-8%)

- Silica gel (particle size 2-5mm)

- Activated alumina

- Molecular sieve

- Treatment process:

- Contact method: direct mixing and stirring of oil and adsorbent

- Percolation method: oil passes through the adsorbent bed

Special treatment technology

1. Electrostatic oil purification technology

- Applicable objects: fine particles (0.1-1μm) and colloidal substances

- Electric field strength: 10- 20kV/cm

- Treatment effect: More than 99% of submicron particles can be removed

2. Centrifugal separation technology

- High-speed centrifuge: speed 6000- 15000 rpm

- Processing capacity: suitable for waste oil with high water content (>1000ppm)

- Advantages: no consumption of filter material, suitable for large-scale processing

3. Membrane separation technology

- Ultrafiltration membrane: molecular weight cutoff 1000-300000 Dalton

- Nanofiltration membrane: removes soluble impurities

- Reverse osmosis: deep dehydration

Quality inspection standards

Recycled oil should meet the following key indicators:

- Breakdown voltage: ≥60kV/2.5mm (new oil standard)

- Water content: ≤15ppm

- Acid value: ≤0.03mgKOH/g

- Dielectric loss factor (90℃): ≤0.005

- Interfacial tension: ≥35mN/m

Precautions

1. Safety protection:

- Firefighting equipment should be equipped at the processing site

- Operators should wear protective equipment

- Do a good job of grounding during electrostatic treatment

2. Environmental protection requirements:

- Waste adsorbents should be treated as hazardous waste

- Pickling wastewater should be discharged after neutralization

- Waste gas should be collected and treated

3. Economic considerations:

- Treatment costs should not exceed 60% of the price of new oil

- Severely aged oil (acid value>0.5mgKOH/g) is not recommended to be regenerated

4. Equipment maintenance:

- Regularly ｒｅｐｌａｃｅ filter elements

- Vacuum pump oil is replaced every 500 hours

- Regularly descale the heating system

By reasonably selecting the treatment process, about 80% of transformer waste oil can be restored its performance and realize resource recycling. For transformer oil of 500kV and above, it is recommended to entrust a professional oil service company to handle it.