After a long time of operation, transformer oil is oxidized and produces a series of oxidation products, which destroys the original excellent physical and chemical properties, as well as electrical properties, therefore it is unable to meet the use standard. Usually, this kind of transformer oil with heavy degree of oxidation is called waste transformer oil.
In fact, only a small part of the oxidation products in waste transformer oil, around 1-25%, while the other 75-99% are ideal components.
The regeneration treatment of transformer oil is to remove harmful substances in transformer oil by physicochemical or chemical methods, and to restore or improve the physical, chemical and electrical performance indexes of transformer oil.
The common regeneration method of transformer oil is Adsorbent method (physicochemical method, suitable for oil with less oxidation and metamorphism).
1. There are two methods of adsorbent method:
a) Contact method - a regeneration method (agitation) in which the powder adsorbent is in direct contact with the oil.
b) Percolation - mainly uses granular adsorbent, which is put into a special adsorption tank (filter element), and let the transformer oil passes through the adsorption tank to achieve the purpose of purification and regeneration. This method can work online. Transformer Oil Regeneration Machine (Model DVOP-R) and Standalone Oil Regeneration Device (Model RD) developed by PURETECH is this type.
2. Type and performance of adsorbent:
a) Activated clay - used for regeneration treatment of transformer oil by contact method, the components that can be adsorbed: moisture, unsaturated hydrocarbon, resin and asphaltene organic acid, etc.
b) Silica gel - the components that can be adsorbed: water, gas, organic acid and other oxidation products.
c) Active alumina - components that can be adsorbed: organic acids and other oxidation products.
d) 801 adsorbent (5A molecular sieve) - components that can be adsorbed: water, gas, unsaturated hydrocarbon, organic acid and other oxidation products).
3. Factors affecting the regeneration of adsorbent:
a) Oil temperature - the best use temperature of different adsorbents should be selected, for example, when using silica gel adsorbent, the temperature is generally 30-50 ℃, 801 adsorbent, and the temperature is generally 50-60 ℃.
b) The effect of contact regeneration is related to temperature, contact stirring time, performance of adsorbent, dosage and other factors. The best processing conditions should be determined according to the deterioration degree of transformer oil and small-scale test.
Attention: the regenerated transformer oil can only be used after strict filtration and purification (our system install multi-stage filter to further filtrate the regenerated transformer oil), so as to prevent the residues such as adsorbent from being brought into the operation equipment.
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