OIL FILTRATION SYSTEMS
The purpose of oil filtration is the removal of water, moisture, contaminates, and other undesirable components from the insulating oil. All of these undesirable components work to deteriorate the stability of oil and the oil’s ability to resist the effects of molecular oxygen. Contaminates work to reduce the oil’s electrical insulating properties and ability to flow at low temperatures. Such “undesired” components are unsaturated hydrocarbons, nitrogen and some sulfur compounds, asphalt- resinous substances, polycyclic hydrocarbons with short side chains (naphthenic, aromatic and naphthenic, aromatic), and solid hydrocarbons, primarily paraffin and ceresin.
Transformer oils deteriorate over time and the decay begins from the moment the transformer oil is shipped from the manufacturer’s factory. High temperatures, the presence of oxygen, water, and the catalytic action of the materials within the transformer all combine to cause the oxidation and cracking of the transformer oil. The by-products of this oxidation process are acidic in nature, and result in an ever increasing rate of deterioration of the transformer and its oil. Oil contaminated with these highly undesirable substances will lose its insulating properties and will shorten the life of the transformer. The insulating properties of transformer oil therefore, should be and must be maintained periodically by filtering the oil through special oil filtration equipment as follows:
The following describes different methods of purification:
Acid-alkaline filtration.
Reduces the process of distillate sulfuric acid concentration up to 93-98%. Consumption of acid depends on the chemical composition of raw materials and the given depth of treatment ranges from 5 to 20% with respect to the cleaning distillate.
Selective filtration
Selective filtration consists of the use of an extraction solvent for the removal of undesirable components. The action of selective solvents is based on a selective solvent in which the solubility of different individual chemical compounds of groups that constitute the distillate.
In the transformer maintenance industry, cleaning is carried out in the extraction column, where distillate and the selective solvent is contacted on special plates. The solvent was fed up the column, and the distillate is placed at its bottom. Phenol, sinking and liaising with the distillate, extracts the undesirable components.
De-waxing of oils
This method may be performed in at least two different ways: (1) by separating solid crystal hydrocarbons (mainly paraffin) from the solution during cooling; and (2) by forming a complex n-paraffin with urea and its separation, etc.
Contact filtration
It is based on the the oil being mixed with bleaching earth (clay). It is then exposed to excessive heat for a period of time necessary for completion of the adsorption process, and is then filtered to separate the oil from the clay.
Regeneration
Regeneration is the most complete and most effective means of performing transformer preventive maintenance. Regeneration is now done by the industry leading GlobeCore Process that uses a sorbent filtering process that not only purifies, but completely regenerates the insulting oil. Regeneration is a complete process that removes the acids, particulate matter, water and moisture and other undesirable contaminates from the oil, core and the insulating paper. Regeneration of transformer oil destroys furan compounds used for predicting the degree of polymerization (“DP” status and life expectancy of the insulation). Analysis of transformer oil should be made prior to performing the maintenance process to determine the “Acid Number” of the oil. If the acid number is 0.08 or above, the oil needs to undergo the GlobeCore Regeneration Process. Oil that is allowed to rise above a 0.08 acid number will shorten transformer service life and increase the chances of a transformer failure and service disruption.
The GlobeCore Process combines Oil Purification and Oil Regeneration into one complete and simple process known as the “Two for One Engineering Miracle.” The GlobeCore Process is performed with the CMM-R series of units that utilize a “Fuller’s Earth” filtration system that automatically reactivates the spent sorbent materials allowing for a continuous, and uninterrupted regeneration process.
The GlobeCore Process has greatly advanced the regeneration process because it performs two very important functions that were not available with older purification and sorbent filtering systems used in the past. (1) The GlobeCore Process is able to completely clean and dry the entire transformer removing the water, moisture, and contaminates from the windings and the insulating paper. The purification process alone cannot clean the windings and the paper and was an incomplete process. (2) In the past, the use of a “Fuller’s Earth” filtering system required the constant disposal of spent sorbent. The process was labor intensive, time consuming and very damaging to the environment and underground water systems. The highly advanced GlobeCore CMM-R units automatically reactivate the sorbent material after every regeneration cycle and continue to re-use the sorbent up to 300 cycles. This eliminates sorbent disposal problems and reduces operating costs.
Regeneration is now the preferred method for long term transformer maintenance because it provides the best value over all other maintenance methods.
The Main factors supporting the high economic efficiency of regeneration include, but are not limited to the following:
- No used oil disposal costs
- No oil transportation costs
- Greatly reduced new oil costs
- Reduced labor costs
- Costs for regeneration can be as low as 10% of the cost of replacing the old oil with new oil.
- Little or no environmental risks
Its time to get with the Process, The GlobeCore Process!