Transformer Oil Regeneration & Filtration

REOIL Transformer oil regeneration plant

Most power equipment is using transformer oil for its dielectric properties for cooling, insulating, and protecting the active parts. Transformer oils are highly refined oils that consist mainly of a mixture of hydrocarbons. Over time, oxidation by products start to form in the oil. Increases 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 is losing its dielectric 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.

Description of oil regeneration process

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 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 individu- al columns, the reactivation process is initiated. During the process, the impurities are removed from the sorbent which restores 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.

Features

• • Electrical heaters with surface efficiency below 1.1 W/cm, with indirect heating to prevent local overheating
• • Fully automatic operation of the REOIL units optionally controlled by PLC and operated via SCADA
• • High vacuum double or single stage coalescer based dehydration and degasification section
• • Filter rated up to 0.5 microns prevents particles from entering back into the transformer
• • Oil catch pan to prevent accidental spillage, with automatic shutdown control
• • Variable flow rate of oil is an integral part of the REOIL plant design allowing the users full flexibility during oil treatment
• • Automatic removal of corrosive sulfur from transformer oils
• • Integrated inhibitor vessel
• • Possibility of full manual control
• • Single or dual bank application for parallel processing
• • Dual storage tank for proper separation of process and waste oils
• • Unique reactivation technology with careful monitoring and fine-grained control of the reactivation process
• • Reactivation technology executed under vacuum conditions with thin columns diameter
• • Unique internal cleaning process to remove any reactivation residues from equipment after reactivation
• • Highly efficient regeneration sorbent with large surface areas a porosity
• • Possibility of remotely access to the unit via integrated GSM modem
• • SCADA system localized to most popular languages
• • Full set of documentation also in electronic form available for download

Performance

The level of contamination differs from transformer to 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 dielectric 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 REOIL 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 those put into the transformer for the first time.

REOIL transformer oil regeneration equipment is inherently designed to remove corrosive sulfur compounds from transformer oils. Sulfur, as well as elemental (free) sulfur (classified as S8), is removed so that treated transformer oil meets the IEC 62697-1 (DBDS) and IEC 62535 standards. Due to the highly efficient sorbent used inside the REOIL equipment all reactive sulfur compounds are removed completely from the oil after treatment. Due to the careful monitoring and fine-grained control of the reactivation process, the equipment ensures that there is no introduction of any elemental (free) sulfur (classified as S8) into to the residual oil after treatment.

 

Property (Unit)	IEC 60422	Before processing	After processing	10 years after processing
Corrosive sulfur (IEC 62535, DIN51353)	Non-corrosive	Corrosive	Non-corrosive	Non-corrosive
DPDS (ppm) (IEC 62697-1)	<5	110	<5	<5
Breakdown voltage (kV/2,5 mm)	>60	39	95	81
Dielectric dissipation factor at 90 °C	<0,01	0,22	0,001	0,005
Acidity (mg KOH/g)	<0,03	0,35	0,010	0,025
Water content (ppm)	<10	39	4	9
Interfacial tension (mN/m)	>35	11	48	41

Technical data