oi regeneration

GlobeCore: Oil Regeneration Extends Transformer Life by 20 Years Globecore GmbH, a German company, manufactures equipment which extends power transformer service life by 20 years

Transformer Oil Regeneration Unit CMM-12R at electricity substation. (Image source: Globecore)

Globecore protects and saves millions of dollars of investments in power transformers. This is achieved by transformer oil purification, which can be performed on site, with the transformer energized. Old oil is reused. Transformer oil is used in power and instrument transformers, as well as oil-filled switchgear. The oil insulates energized parts of the equipment, dissipates heat and extinguishes the arc in switches.

Transformer oil is used in power and instrument transformers, as well as oil-filled switchgear. The oil insulates energized parts of the equipment, dissipates heat and extinguishes arcs in switches.

What are the hazards of transformer oil contamination?

The transformer lives as long as its insulation system. Transformer gradually accumulates oxidation products, contaminants and other impurities over time when used. Oxygen and water in the insulating fluid provokes oxidation even under ideal operating conditions. Particles originating from the construction materials of the transformer are also a problem.

The process of oxidation results in formation of acids, which act on carbon and metals, forming aldehydes, alcohols and soap metals. These substances deposit on solid insulation. Contaminants increase oil viscosity, hampering circulation and cooling.

Therefore, aging of transformer oil is a consequence of combined effects of high temperature, oxygen, and electric field in the presence of the transformer construction materials. Important operational parameters of the insulating fluid (acidity, dissipation factor and dielectric strength) are very sensitive to its aging. The higher the intensity of the process, the sooner they reach critical levels, and the oil becomes impossible to use.

Using such oil is also dangerous to the transformer: the risk of failures and power outages increases significantly.

What to do with used transformer oil?

Accumulation of waste transformer oil is a serious environmental concern. Consider this: over 40% of waterways in the world are contaminated and covered with a film of waste oil. One liter of waste oil makes a million liters of groundwater unusable! Plants and animals die due to massive pollution with oil products. Besides, waste oil contains carcinogenic substances. Dumping of waste oil into the environment is entirely unacceptable. So what is the solution and how to preserve the planet for future generations?

There is a solution: restoration of transformer oil to its initial condition and reusing the oil. Beside the pronounced environmental benefits, this solution allows to save on purchasing new and disposing of used oil, as well as to extend transformer lifetime by 20 years or more. At this time, the cost of one power transformer reaches, on average, hundreds of thousand US dollars. The number can easily reach into the millions, if the costs of disassembling the oil unit, transporting and installing a new transformer are factored in.

Methods of transformer oil regeneration

Let us consider several techniques used in regeneration of used transformer oil.

Centrifuges. These devices are large drums in sealed cases. The drum consists of a number of conical plates with orifices. Centrifuges are used for removal of moisture and solid particles. At one time centrifuges were widely used in oil processing facilities despite their limitations, such as low capacity, complex design, intensive mixing of the processed oil with air and large footprint. With time, compact mobile units for oil treatment were developed, and the number of centrifuges operated is now on decline.

Electric purification. Electric purification is based on the uneven influence of the electromagnetic field on contaminants in transformer oil, which causes the impurities to settle on electrodes. The biggest limitation of this method is the complexity of cleaning the deposits from the electrodes. Also, electric purification cannot remove water. Due to these reasons, this approach has not been widely implemented 

Adsorption. This technique involves percolation of oil through a layer of adsorbent (silica gel in most cases), loaded into a vertical cylinder. Silica gel is produced by a series of chemical reactions, making the material rather expensive. Besides, there is a problem of silica gel disposal, since oil-contaminated materials must not be released into the environment.

The alternative is purification of transformer oil with Fuller’s earth, a natural adsorbent. Due to its porous structure, this material has good adsorptive qualities and can be used both for continuous regeneration of transformer oil from dehydrating breather filters, and also for restoration of oil drained from a transformer.

Generally, Fuller’s earth must somehow be disposed of, just like silica gel. However, GlobeCore process allows to reactivate and reuse the sorbent for transformer oil regeneration many times over.

Thermovacuum dehydration and high vacuum degassing. The GlobeCore process using heat and high vacuum ensures the best parameters of transformer oil. Operation of these units is environmentally safe and does not involve special disposal or storage.  

GlobeCore environmental solutions

For many years, GlobeCore has been developing and implementing technologies for restoration of used transformer oil.

The company has successful experience in servicing power transformers of land based and offshore wind farms. We offer a range of units specifically tailored for these purposes.

The UVM type units degas oil and remove particulate matter by a combination of heat, vacuum and filtration. This unit reduces moisture content to 5 ppm and gas content to 0.1% or less and increases dielectric strength to 70 kV.

The CMM-R regeneration plants extend transformer lifetime by restoring the dielectric strength and chemical composition of transformer oil. This equipment allows to regenerate oil directly in an energized transformer. Connecting a CMM-R to an operating transformer allows to remove sludge from the windings and extract it from the oil by the sorbent. These units are loaded with Fuller’s earth.

The GlobeCore regeneration process has the capability of continuous processing of transformer oil, saving on new oil and disposal of saturated sorbents. Fuller’s earth can be reactivated up to 300 times, the equivalent of 1.5 - 2 years of operation or regeneration of 1000 tons of oil.

GlobeCore also cares about environmental safety of other machines which use adsorbents. The SSZ-15 zeolite drying cabinet can pre-dry zeolite to improve adsorption and the quality of oil dehydration. The CMM-4RP, one of GlobeCore latest developments, allows reactivation of saturated sorbents used in transformer oil regeneration systems. The technology can reactivate the same sorbent at least 10 times. The reactivated sorbents contain no residual oil and, if necessary, can be disposed of a regular household waste without harm to the environment.

Therefore, GlobeCore transformer oil filtration technologies allow to:

- save on purchasing new and disposing of used oil;

- significantly lower industrial load on the environment;

- extend transformer life by at least 20 years.

In conclusion, we would like to show some numbers to emphasize the economic feasibility of used transformer oil restoration:

- average market price of regenerating one liter of transformer oil is $0.7-0.8;

- average price of one liter of new transformer oil is $1.5-2.

For more informations visit our website:https://globecore.co.za/

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