How to deal with waste transformer oil?

The treatment of waste transformer oil needs to comply with environmental regulations (such as the Basel Convention and national hazardous waste management regulations), while taking into account resource recovery and the economy. The following is a professional treatment plan in steps:

Pretreatment and classification

1. Detection and analysis

- Determination of key indicators:

- Electrical performance (breakdown voltage, dielectric loss)

- Pollutants (water, acid value, PCB content)

- Metal elements (dissolved copper, iron, etc.)

- Classification standards:

- Renewable oil: acid value <0.5mg KOH/g, dielectric loss <4% (40℃)

- Oil to be disposed of: PCB >50ppm or severely carbonized

2. Preliminary filtration

- Remove suspended particles through a 10μm filter element to protect subsequent equipment.

Regeneration technology (applicable to renewable oil)

1. Physical purification method

- Vacuum dehydration and degassing

- Conditions: -95kPa vacuum + 60℃ heating, treatment to moisture ≤15ppm

- Equipment: thin film evaporator (such as GEA's falling film system)

- Centrifugal separation

- Remove free water and particles >1μm (Alfa Laval BTPX series efficiency >98%)

2. Chemical regeneration method

- Adsorption treatment

- Activated clay: Add 3~8% clay and stir to adsorb (reduce acid value to 0.03mg KOH/g)

- Molecular sieve: Selectively adsorbs polar compounds (such as silica gel adsorption tower)

- Alkali washing-clay combined process

3. Deep refining

- Hydrogenation treatment

- Reduction of aging products under a catalyst (Ni-Mo) and high pressure (5MPa) to restore antioxidant properties

- Cost: about $150/ton, suitable for large-scale treatment

Harmless disposal of non-renewable oil

1. High-temperature incineration

- Rotary kiln incinerator: Completely decomposes PCB above 1200℃

- Requirements: Equipped with a dioxin control device (quenching tower + activated carbon adsorption)

- Compliance: A hazardous waste management license is required (such as EU WID certification)

2. Solvent extraction

- Supercritical CO₂ extraction: Separation of PCB and other toxic substances (recovery rate > 99%)

- Applicable: Oil containing PCB 50~500ppm

3. Solidification treatment

- Add cement/sulfur solidification and safe landfill (only when there is no other treatment option)

Resource utilization

1. Fuel

- Modulation of industrial fuel oil (must comply with GB 17145 standard)

- Calorific value ≈40 MJ/kg, equivalent to 90% of diesel

2. Lubricant base oil

- Produce Class II base oil through hydroisomerization (such as Neste's process)

3. Asphalt modifier

- Add 5%~10% to improve the low-temperature performance of road asphalt

Compliance process and cost comparison

| Treatment method | Cost ($/ton) | Compliance requirements | Residue treatment |

|--------------------|-------------|--------------------------|---------------------|

| Physical regeneration | 80~120 | Oil test report required | Filter residue (hazardous waste code HW08) |

| Chemical regeneration | 150~200 | Chemical use permit | Waste white clay (HW13) |

| High temperature incineration | 300~500 | Hazardous waste disposal qualification | Fly ash (HW18) |

| Solvent extraction | 400~600 | PCB processing special license | Extraction residue (HW09) |

Operation precautions

1. Safety protection

- Wear Class A protective clothing (such as Tychem QC suit) when contacting PCB

- Use ATEX-certified equipment in explosion-proof areas

2. Recording and tracking

- Use the ERP system to record oil flow throughout the process (meet EPA 40 CFR Part 262)

3. Best practice cases

- Ecohuile Company of France: Integrated "centrifugation-hydrogenation-blending" process, annual processing of 50,000 tons of waste oil

- China State Grid "Green Oil Plan": Establish a regional centralized processing center, and the reuse rate of recycled oil reaches 73%

Recommended suppliers

- Regeneration equipment: Alfa Laval (Sweden), GlobeCore (Ukraine)

- Disposal services: Veolia (France), Clean Harbors (USA)

- Testing agencies: SGS, Intertek (Global Pass Report)

Life cycle assessment (LCA) is required when selecting a solution, with recycling being a priority. For developing countries, modular mobile treatment stations (such as the containerized units of Thermax in India) are recommended, which can reduce investment costs by 40%.