The exploitation of transformer oil leads to the loss of its original color. Oil discoloration is one of the indicators of profound physicochemical changes. There are various factors causing oil darkening, but they are mostly associated with its contamination by various impurities and oxidation products.
Adsorption refining is the most effective technology in the performance of a transformer oil bleaching task. It is based on the absorption of harmful impurities using special substances called adsorbents.
Synthetic Zeolite is most commonly used for the elimination of water. The effectiveness of zeolites is determined by their structure, particularly, by the presence of charged oxygen ions on the surface of the pores. They provide a high adsorbent capacity, especially in relation to the polar water molecules.
The type of the adsorbed substance depends on the size of pores’ inlet holes in which molecules can permeate. That is why zeolites are sometimes called “molecular sieves.” The adsorption of the transformer oil’s molecules does not occur because, as a rule, the size of the oil molecules is much larger than the size of contaminant molecules. Therefore, they are unable to pass through the zeolite pores.
Pure zeolites have the form of a fine crystal powder. But, this form is inapplicable for practical purposes therefore, zeolite granules are used. Their mechanical strength fully comlies with all necessary requirements. Adsorption refining of transformer oil by means of zeolites removes the dissolved moisture found in the oil.
Natural adsorbents may also be used to remove impurities from the oil. First of all we are talking about bleaching earth. Fuller’s earth is highly efficient in the context of transformer oils processing.
Fuller’s earth is a soft clay product found in the montmorillonite group of minerals that form microscopic chrystals. The main feature of this adsorbent is the lattice pattern it forms that allows for the adsorbing of various ions (mostly cations) as well as providing an ion exchange.
Fuller’s earth is most frequently used for the processing of petroleum products. Transformer oils are no exception – they are also bleached with Fuller’s earth.
GlobeCore has developed and supplies bleaching equipment for transformer oil processing. Today GlobeCore manufactures several different equipment models using the principle of adsorption with the application of various adsorbents. This provides many choices in finding the optimal equipment for each specific customer’s needs.
Special attention should be paid to GlobeCore’s СММ-R-type plants designed to purify, regenerate and bleach transformer oils. They consist of separate blocks for filtering, degassing, regeneration and adsorbent reactivation. Fuller’s earth is used as the adsorbent in the the CMM-R line of equipment. The adsorbent has a capacity of 300 reactivations which is equivalent to between 1.5 to 3 years of operation.
It is possible to connect СММ-R plants and to process oil directly in an operating transformer. It reduces operating costs and eliminates possible electrical supply interuptions.
Transformer oils recycled by GlobeCore СММ-R units are fully restored to their original performance characteristics and can be reused for the service life of the transformer.
The equipment for transformer oil purification, that is manufactured and supplied by GlobeCore, is mobile, eco-friendly and energy efficient.
