Do you want to know what is Transformer Oil Purification? How to do oil filtration? Or what is oil purification process?
In this article, you will understand transformer oil purification process, steps and methods involved in oil purification process. Oil purification is a process to remove sludge, dissolved moisture and dissolved gases from the oil.
Before we move to process details, Let’s see why transformers need to purify oil?
Here we will see in brief advantages for transformer oil purification:
Improved insulation properties of the oil and hence the other media like paper/cellulose insulation.
Better the insulation of transformer, longer the life of the transformer and the breakdown of the transformer.
Longer the life of the transformer asset, good returns on investment of the asset.
Lesser breakdowns and failure of the transformer results in uninterrupted power supply.
For best performance of transformers, we require filtration machines designed and manufactured to standards.
At SERVKON, we supply Oil purification machines with Standard (BIS, NEMA, IEEE, IEE, ASTM, ASME, IEC) for good performance of transformer.
Now let’s move to, Oil Purification Procedure.
Transformer Oil Purification Procedure
The transformer is one of the main in the electrical power industry which needs to be maintained for guaranteed uninterrupted power transmission in order to get assured revenue benefits.
Transformer life mainly depends on the quality of oil volume it contains.
Regular oil filtration assures long and consistent results from the transformer. Oil purification is a process to remove sludge, dissolved moisture and dissolved gases from the oil. Transformer oil conditioning may also include to some extent improving the acidity of the oil.
A good oil purification system is able to deliver filtered oil with parameters as per the standard specification. However, this revival of the oil by oil filtration plant to standard oil parameters is based on the quality of unprocessed oil and its initial process. In case the unprocessed oil does not match the standard oil parameters, then the effort of transformer oil filtration is all in vain. method of regeneration of oil should be adopted in this case.
Here we shall look at the method of the transformer oil filtration by vacuum type dehydration and centrifuge type removal of solids and water separation.Transformer oil conditioning is a streamline oil filtration process of sludge purification, moisture and gas removal.
1. First step in the transformer oil purification
The first step in this serial process is to raise the oil temperature to level, generally up to 65 Deg C. This aids to give the oil latent heat, which later aids, to dissociate the moisture and gases from oil in the degassing chamber. Additionally the viscosity of the oil drops, which aids in better filtration to some extent. Recommended heater design should consider an area of heating of about 1 to 2 W/https://www.linkedin.com/redir/malware-page?url=sq%2ecm%2e In the transformer oil purification plant, the heating system is protected against built up and excess temperature rise.
2. Second step of transformer oil purification
The second step of oil purification plant is of sludge and dirt from the transformer oil.
Two methods have been used for removal of the sludge:
- Removal of sludge by filter candles.
- Sludge removal by centrifuging action.
Removal of sludge by filter candles.
Transformer oil filtration using filter candles in the transformer oil purifier machine can further be classified as:
- Filtration using the classical edge filter.
- Filtration of oil using the depth type filter.
Both methods of cartridge type filtration are prevalent and owe certain advantages and disadvantages.
The edge type filter system can be cleaned and be reused for at least three to four times, however, cleaning and fitting of the edge filters involves considerable time and human effort. This system is robust to handle quantity of sludge. Edge filters can be cleaned by reverse pressurized dry air/nitrogen flow in order to remove the contamination. After the paper stack is removed and dried in oven/ bright sunlight and reused. This operation demands experience and skill set.
New trends and technology in the market have driven transformer oil filter machines to use filter cartridges instead edge type paper stacked filters. These cartridges are similar to those of the water filter cartridges and can be selected from a variety of purification range say from 500 to size.
The advantage using these cartridges over the edge filter is:
- No moisture storage, since the filter media used can be non-hygroscopic.
- Easy to replace with less human effort and easy availability.
Removal of sludge by centrifuging action.
An alternate method used for dirt separation of oil is centrifuged. Routine oil filtration or transformer oil conditioning is often confused with transformer oil centrifuging. Oil centrifuging is a different technology and has a little impact on improving the oil parameters. Centrifuges, used for separation of dirt from the oil can be slow speed type centrifuges that do not require an additional electric motor to spin the centrifuge cone at high speed.
However, the dirt separation of oil with such centrifuging has limitations since these centrifuges cannot remove the dirt less than level. Thus a centrifuge becomes evitable which scales up the cost of the oil conditioning machine.
The only advantage of the centrifuges is the recurring cost of changing filter elements is saved. centrifuges can remove water from the oil that is in free form, but not the dissolved moisture. Manufacturers of centrifuge also often not guarantee removal of moisture to a level less than 5 ppm.
3. Third step in the oil filter machine
The third step in the oil filter machine is dehydration of transformer oil and degasification of the oil.
Dehydration and Degasification of transformer oil, These processes of dehumidification of oil and removal of gasses are executed in the degassing chamber. The dissolved water, oil separation or dissolved gas, oil separation is possible at reduced pressure, i.e. vacuum, due to the difference of boiling point of water, gas and oil. In the process of separation of gases it becomes important to retain the aromatic hydrocarbons so that the original properties of the oil are retained. When the water level in the oil is above the saturation level of transformer oil, oil is observed in free water. Removal of free water can be done by centrifuge or by coalescing principle.
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