Transformer Oil Recycling Plant

Product Range:

Thermopac currently manufactures Transformer Oil Regeneration equipment with sorbent and reactivation capability technology. Oil regeneration plants are of modular design with a variable number of columns and a rotating equipment skid for housing pumps, controls and control cabinet. Transformer oil treatment plants are available in different oil flow ranges from 1500 l/h up to 12 000 l/h. Oil treatment plants feature highly efficient design to achieve the most efficient dehydration, degasification and finishing Transformer Oil. Oil treatment equipment uses double stage high vacuum technology together with a variable flow to efficiently control the oil speed.

Description Of Oil Regeneration Process:

Most power equipment is using transformer oil for its di-electric properties for cooling, insulating and protecting the active parts. Transformer oils are highly refined oils that consist mainly of a mixture of hydrocarbons. Over a period of time, due to oxidation, by-products start to form in the oil. Increase in oxidation by-products result in the increase of acidity (neutralization number) and decrease the interfacial tension of the oil. At this stage, sludge starts to form, and oil starts losing its di-electric properties because it is getting old. To prevent further deterioration of oil and possible damage to the active part of the transformer, oil needs to be regenerated. Oil regeneration equipment regenerates oil in steps. At the inlet of the equipment, oil is filtered through a coarse filter to prevent any particles from entering the equipment.

It is then heated to the desired temperature to elevate the regeneration effect. After the oil has been heated, it enters the back section of the equipment. Oil is pumped through the back section which houses columns with sorbent media. It is in this section where the oil is stripped of all impurities and ageing by-products. Oil is then pumped through a vacuum breaking valve into the degassing section where it is dehydrated and degassed. Treated oil is then pumped back to the transformer oil tank by the outlet pump. After a given period, sorbent in the back section of the equipment achieves full saturation and is no longer able to regenerate oil. At this stage, the sorbent needs to be reactivated or to be restored to its original state to be able to regenerate oil.

Reactivation stage starts by draining the columns in the back section saturated oil tank. After the oil has been drained, a vacuum is created and maintained throughout the whole reactivation process in the back section. Then by selective use of heating elements on the top parts of individual columns, the reactivation process is initiated. During the process, the impurities are removed from the sorbent to restore it to its original state. This entire process can be repeated many times until the sorbent starts to lose its properties and needs to be replaced.

Steps Oil Regeneration

  • Filtered through a coarse filter to prevent any particles from entering the equipment, it is then heated to the desired temperature to elevate the regeneration effect
  • After the oil has been heated, it enters the back section of the equipment. Oil is pumped through the back section which houses columns with sorbent media. It is in this section where the oil is stripped of impurities and ageing by-products
  • Oil is then pumped through a vacuum breaking valve into the degassing section where it is dehydrated and degassed. Treated oil is then pumped back to the transformer by the outlet pump
  • After a given period, sorbent in the back section of the equipment achieves full saturation and is no longer able to regenerate oil
  • At this stage, the sorbent needs to be reactivated (restored to its original state) to be able to regenerate oil again. Reactivation stage starts by draining the columns in the back section of saturated oil.
  • After the oil has been drained, a vacuum is created and maintained throughout the whole reactivation process in the back section.
  • Then by selective use of heating elements on the top parts of individual columns, the reactivation process is initiated. During the process, the impurities are removed from the sorbent to restore it to its original state. The off gases generated during this process are decomposed in thermal oxidizer before released to chimney.
  • This entire process can be repeated many times until the sorbent starts to lose its properties and needs to be replaced.

Technical Characteristics Of Oil Regeneration Equipment

Transformer oil regeneration process is completely automated by PLC and SCADA. Its inlet pump is a positive displacement rotary pump. The outlet pump is a centrifugally closed coupled high suction pump. For degassing the rotary vane, a vacuum pump and vacuum booster roots pump are used. For the reactivation phase, a rotary piston roots pump is used. All valves across the equipment are automatic ball valves, which are pneumatically controlled. Equipment is fully automatic, controlled by PLC logic and interfaced with a SCADA system. Numerous safety features are introduced throughout the unit to ensure the safety of the equipment as well as the operating personal. Aeration valves, overheating protection, and automatic level switches guarantee the safety of the equipment as well as its ability to identify a possible risk and to power down to prevent any accidents.

Technical Characteristics Of Oil Regeneration Equipment
Model Oil flow(l/h) Max Output (LPD) Piping (DN) Power (kW)
TTOR-2000 4000 20,000 40 80
TTOR-4000 8000 40,000 50 140
TTOR-6000 12000 60,000 80 200

Performance Values Of Oil Regeneration Equipment

The level of contamination differs per transformer. The ageing process, as well as the utilization of a transformer, make it difficult to determine when and how will oil age to the point that it loses its di-electric properties. Regardless of the level of contamination, oil regeneration always delivers the result required by the IEC 60422 standard for mineral insulating oils in electrical equipment. However, our Thermopac regeneration technology goes one step further and significantly improves on the values required by the IEC 60422 standard, with the returning oil having properties almost identical to new transformer.

Performance Values Of Oil Regeneration Equipment
Property (Unit) IEC 60422 Before Regeneration After Regeneration
Breakdown Voltage (kV/2,5 mm ) >60 49 95
Di-electric Dissipation Factor at 90 °C <0,01 0,0823 0,0008
Acidity (m g KOH/g) <0,03 0,15 0,010
Water Content (ppm ) <10 35 6
Interfacial Tension (m N/m ) >35 27 49
Codes and Standards

  • American Society of Testing Materials (ASTM)
  • American Society of Mechanical Engineers (ASME)
  • American Petroleum Institute (API)
  • Tubular Exchanger Manufacturer’s Association (TEMA)
  • Bureau of Indian Standards (BIS)
  • Local Standards where the plants will be located
Advantages of the Process

  • Environment friendly
  • Highly efficient with latest technology
  • Minimum contamination and rework
  • PLC Automated, with SCADA system
  • Skid mounted – Expandable, reduces set-up cost and time
  • Modular construction
  • Handles a variety of lube oils