Category Archives: Solutions

The article considers  types of turbine oil contaminants, as well as negative consequences to which they may lead.

Application of GlobeCore oil filtration stations reduces costs of turbine oil operation, reduce oil consumption, increase its performance and avoid unscheduled stops of power plants.

Prolonged operation of turbine oil leads to accumulation of various impurities in oil system:

• gelled oil aging products;
• corrosion products;
• mechanical impurities with  wear product ;
• foreign matter.

With no action, the turbine oil contamination can lead to:

• emergency shutdowns of  equipment;
• unscheduled repairs;
• underproduction of electricity;
• high costs for oil replacement.

Application of GlobeCore filtration systems:

• reduce operating costs;
• reduce oil consumption by extending its operating life;
• reduce environmental impact by reducing the amount of waste;
• maintain oil performance for a long exploitation;
• improve  lubrication system and turbine control;
• reduce costs of repair works;
• ensure smooth operation without shutdowns;
• eliminate financial expenses for oil purification by third parties.

Features and benefits of CFU – М oil filtration unit, designed for turbine oil processing:

• purify oil using a thermal vacuum method in one cycle;
• easy to maintain and operate;
• extend service life of oil;
• spare parts come with the plant.

Transformer oil contains up to 10% air (by volume) at atmospheric pressure. This significantly accelerates its oxidation and reduces dielectric strength. Therefore, the oil in large transformers must be degassed. Before putting the oil into the transformer, the residual gas content must be brought to less than 0.1% volume.

The CMM-4/7 by GlobeCore is designed for degassing, used oil removal of solid particles and heating of transformer oil in power transformer with voltages up to 1150 kV.

This product is used by transformer installation, maintenance and repair facilities, as well as transformer oil service facilities.

Principles of operation

The CMM-4/7 operates on the principle of thermal and vacuum degassing and drying of transformer oil without used oil removal, eliminating the need for centrifuges and special sorbents.

Oil is filtered by 5 µm filters. Using both processes allows to bring processed oil to the following speicifcations:

• weight moisture content – 5 g/t;
• nominal filtration – 5 µm;
• gas content by volume – 0,1%;
• dielectric strength – 70 kV.

Advantages:

• no harmful emissions or waste requiring special disposal or storage;
• small footprint;
• mobility and onsite use;
• simple design, easy servicing and operation;
• foam control system;
• oil paper insulation drying;
• GSM-module for remote control of the unit’s operation;
• outstanding results after even one pass of the oil through the unit;
• low energy consumption;
• low noise emissions.

Specifications

Parameter			Value
1. Capacity, m3/hour, not less than
		–      degassing drying and filtration mode		4,0
		– heating and filtration mode		7,0
2. Capacity adjustment range, m3/hour				0-4,0
3. Max oil output temperature in heating mode, ºС				90
4. Filtration rate				>50
5. Outlet pressure, MPa				0,35
6. Oil output head relative to inlet, n				35,0
7. Electric oil heater power, kW				70
8. Oil heater mean surface power, W/cm2, max				1,1
9. Max power consumption, kW, max				80
10. Power supply
	– voltage, V			380
	– frequency, Hz			50
11. Dimensions, mm
	– length			1650
	– height			1590
	– width			1250
12. Weight, kg, max				920

Client benefits from purchasing the used oil recycling unit:

1. Flowing degassed and purified transformer oil without used oil removal.
2. Transformer oil heating capability — without used oil removal.
3. Ability to heat oil filled electrical equipment with hot oil — we created new heating system globe core.
4. Transformer vacuumizing capability.

Transformer oil is used in power transformer an oil filled switches. This oil facilitate insulation of energized parts of the equipment, heat dissipation and arc extinguishing.

The dangers of transformer oil contamination

Electric power experts agree that the life time of a transformer lasts only as long as the life time of its insulation system. During operation transformer oil accumulates oxidation products, contaminants etc. Oxygen and water in a dielectric fluid provokes oxidation even in perfect operation conditions. Particles of the transformer construction materials are also a factor.

Oxidation is accompanied by formation of acids, acting on carbon and metals, forming aldehydes, alcohols and soapy metals. These form a sediment on the insulation. Contaminants also increase the oil’s viscosity, degrading its heat dissipation function.

Therefore, aging of transformer oil is the results of high temperature, oxygen and the electric field with the transformer construction materials. Important operation parameters (acidity, dissipation factor, dielectric strength) are sensitive to the aging process. The faster it goes, the faster they reach critical limits, making the oil unusable. Using such oil in a transformer is dangerous: the risk of failures and power interruptions becomes high.

What happens with used transformer oil

Waste transformer oil are quite harmful for the environment. Over 40% of water contamination worldwide is caused by waste oil. One liter of spilled waste oil makes a million liters of ground water undrinkable. Mass contamination by oil products kills plants and animals. Besides, water oil contains carcinogenic substances. Dumping of waste oil into the environment is unacceptable.

The solution is to restore used transformer oil to as good as new condition and reusing it. Beside the positive environmental effect, this also allows for significant economy on purchasing new and disposing of oil transformer oil, as well as increase of transformer service life 20 years and longer. At this time, the price tag of a transformer is several hundred thousand dollars on average. The cost of disassembling damaged equipment, transportation and installation of new equipment can reach into the millions.

Methods of transformer oil restoration

Let is look into some of the classic and new methods applied for restoration of used transformer oil.

Centrifuge. A centrifuge is a drum in a tightly sealed body. It contains many conical plates with openings. Such devices are used to remove moisture and solid particles. At one time, centrifuges were widely used in oil handling facilities despite their drawbacks, such as low capacity, complexity, intensive mixing of oil with air and large footprint. With time, compact portable oil restoration units of the required processing capacity have been developed. Therefore the amount of centrifuges in operation became to decline.

Electric purification. This method involves the uneven influence of electrical field on moisture and contaminants in the oil with sedimentation of these on the electrodes. Sedimented moisture and water are removed from the surface of the electrodes with oil and this mix is again supplied for sedimentation. The process lasts until all contaminants are removed.

Percolation. This method involves the percolation of the waste oil through a layer of absorbent (most often silica gel) in a vertical cylindrical vessel. Using adsorbents offers good results, but the material must be disposed of or reactivated after the process. Oil saturated materials cannot be released into the environment.

 

Bleaching clay processing. Silica gel is produced by a series of chemical reactions, making the production process costly. An alternative is using naturally occurring materials, such as bleaching clay. Due to the porous structure, the bleaching clay has good capture capability and can be used for continuous reclamation of transformer oil in filters on transformers and to restore oil drained from a transformer.

GlobeCore’s environmentally friendly solutions

GlobeCore has developed and has been implementing technologies aimed at restoration of waste transformer and high voltage switch oil.

Specifically, the CMM type oil purifier units allow to degas and filter transformer oil by processing the oil under vacuum, heating and passing a section of filters. The equipment reduces moisture content to less than 5 ppm, gas content to less than 0.1 and increases dielectric strength of the oil to 70 kV. The CMM type oil purifier units do not release any substance which would require special disposal or handling.

The CMM-R oil purifier units extend the transformer life time by restoring the dielectric strength and chemical composition of transformer oil. This unit allows to reclaim the oil directly in an on-line transformer. This method also allows to remove sediment from the windings. The sorbent used is Fuller’s earth, the main advantage of which is the multiple use capability. The oil purifier facilitates continuous processing of transformer oil and savings on purchasing new and disposing of oil oils. Projected Fuller’s earth service life is 300 of reactivations, the equivalent of 1.5 – 2 years of operation. After the absorbent is exhausted, it si environmentally safe and can be disposed of accordingly.

GlobeCore also offers environmental solutions for other adsorption based processes. Zeolite drying cabinet ZSC-15 allows to dry the zeolite to improve its adsorption performance and improve the dehydration of oil.

The CMM-4RP unit restores waste absorbent (bleaching clay, Fuller’s Earth etc), used in transformer oil reclamation units. The technologies used allow to reactivate the sorbent up to 10 times. After deactivation, the absorbents contain no oil and can be disposed of regularly without harmful effects.

GlobeCore’s oil restoration technologies allow to:

• save significantly on purchasing new and disposing of used oil products;
• reduce the harmful environmental effects;
• extend transformer service life 20 years and more.

Here are some numbers to further emphasize the economic efficiency of transformer oil restoration:

• average transformer price per 1 KVA – $8-15;
• average market prices of oil reclamation of one liter of transformer oil – $0.7-0.8;
• average price of one liter of new transformer oil – $1.5-2.

Only porous materials,  having a large specific surface, can be adsorbents. To dry air – silica is most commonly used. Silica gel is a result of dehydration of sodium silicate.

The specific surface area of this adsorbent is 400-770 m2 / g and granule size – 0,2-7 mm. At the end of its effective operation the moisture level  is 9-11%. Residual moisture content is  not more than 0.02 g / kg.

With more absorption – the drying gradually reduces, and there comes a moment when the moisture absorption from the air completely stops. In order to restore the absorption properties – it is heated to a temperature above 100 ° C or air dried (150-180ºS temperature).

The process of adsorbing moisture from the air depends on the pressures. The adsorbed water vapor forms a concave meniscus inside a capillary of adsorbent. The partial pressure of water above the concave surface is lower than on a flat surface at the same temperature. Therefore the steam from the air diffuses into the capillary cavity and is condensed there. The intensity of the drying process depends on the difference between the partial pressures of saturated water vapor above the surface of the meniscus and air dried.

In industry there are two types of air drying devices. A device with a continuously rotating absorbing layer or a fixed layer device. The first has 75% of the adsorbent constantly in the stream of drying air The remaining part passes through the stream of hot air, where it is giving away absorbed moisture and restores. In the devices of the second type the adsorbent is not moving: one part is  absorbing moisture and the other – desorbed. Automatic switch changes between the modes after a certain period of time.

There are many factors influencing transformer oil. All of them need to be checked – to provide a good and reliable work of transformers.

Contact with the atmosphere, high temperature and sunlight – are important factors that affect the quality of oil. And the higher the oxidation of transformer oil, the lower its dielectric strength. Oxidation can be estimated using parameters: reaction of water extract and acid number. They are key quality controls. The first shows the presence  of insoluble acids in the oil , and the second – the number of milligrams of potassium hydroxide that is necessary  to neutralize all the free acid. A good transformer oil should have a neutral reaction of water extract.

Low temperatures  – and the pour point of oil is a very important parameter. The less is the temperature – the more is the viscosity of oil, which is leading to the slow circulation  of insulating liquid in the oil-filled electrical equipment

Oil gradually decreases  in the transformer tank, caused by evaporation. Therefore, it is necessary to conduct a regular topping up of dielectric fluid.

If during operation of transformer the insulated liquid  fails to satisfy set requirements, it is necessary to activate the regeneration process. Regeneration – is a recovery of properties of transformer oils, which prolongs their further use for the intended purpose.

To slow the aging process of oil are used:

• Special thermosiphon filters are used filled with silica gel. They have good absorption properties, continuously removing aging products and restoring insulating liquids.
• Nitrogen protection against oxidation. Nitrogen pillows are generated in the transformer tank, to prevent contact of oil with the air,

In the absence of chemical insoluble impurities, water or coal – insulating liquid can be recovered by using

• sedimentation,
• filtration or
• centrifugation.

When treating insulating fluids it is very important to ensure uninterrupted supply of electricity to consumers. This is possible, either with a backup transformer, or using equipment for regeneration while a transformer is in operation. GlobeCore  manufactures such systems.

CMM-R – a regeneration plant, restoring quality of transformer oil to set values by the use of a special sorbent – Fullers Earth. It has a high absorption capacity and removes products of oxidation and aging from the insulating liquid.

After saturation Fuller’s earth  is directly restored in the equipment and can be used for further processing of transformer oil.

During operation transformer oil is exposed to a variety of adverse factors: high temperatures, oxygen, moisture, sunlight, and others. Their overall impact leads to a significant deterioration of the insulating properties of transformer oil. It is moment when you need industrial purification systems.

In order to preserve and extend service life of electrical equipment it is recommended to periodically monitor its operational parameters. Service life of solid insulation of power transformers depends on the degree of polymerization of cellulose. Its destruction most often occurs in an acidic environment, and the intensity of destruction develops along with increasing operating temperature of the equipment. It follows herefrom that service life of solid insulation is directly dependent on the degree of degradation of transformer oil and its operating temperature.

Interestingly, but even in the case of compliance with the existing standards for the acid number there still can be sludge detected in transformer oil, which precipitates in the form of a thin coating on the windings, absorbs into paper and impairs heat removal from the hot parts of the transformer. This also reduces the degree of polymerization of cellulose, and shortens service life of the equipment.

If the operational parameters of transformer oil fall below the rated values, this indicates that the oil can not perform the required functions in full, and thus becomes waste.

As of today, there is still a tradition that provides for replacement of waste oil with fresh. But, despite the fact that the practice of replacing has been evolving for decades, now the technology of reclamation (regeneration) of transformer oil is getting increasingly used. Let’s try to figure out which decision is more practicable: replacement or regeneration?

The major difference between these processes is that the structural-group composition of the regenerated and new oil is not the same even in the case if the oil brands coincide. Over the years of exploitation, oil and paper form a certain kind of symbiosis. Used oil that has passed through the regeneration process stays neutral to the paper that it has been interacting with before. However, if a new oil is filled into the transformer, then, in this case, additional adverse reactions and disruption of the previously achieved equilibrium are possible.

Generally, regeneration of used transformer oil is implies the full restoration of its operational parameters to the rated values. From the technical standpoint, this procedure can be performed by the GlobeCore CMM-R regeneration unit.  The process of removing undesirable components is carried out through Fuller’s earth sorbent, the properties of which are recovered during the regeneration cycle. Such an approach makes processing of transformer oil continuous and without pauses on replacement of the sorbent.

Another important advantage of the CMM-R unit – the ability to regenerate oil directly in the tank of a transformer that is being energized. There is no need in power outage of important objects and civilian users.

You shouldn’t forget about the financial aspect as well, because in the light of the current economic situation it is also very important! Reclamation of used transformer oil will significantly reduce the costs on purchase of fresh and disposal of waste oil. Moreover, by using the GlobeCore Regeneration Process, you will make an important contribution to the preservation of nature, since waste oil is considered to be quite a hazardous and hard-to-degrade waste.