Investigation on the Acid Removal Performance of Oil Regeneration Sorbent Materials

Transformers being one of the most expensive equipment in the networks require proper utilisation, which includes regular maintenance and application of life-extension techniques in feasible situations. Ageing process of the mineral oil and cellulose paper insulation system creates by-products such as moisture, acids and sludge, which further accelerate the degradation of the transformer insulation. Therefore, the removal of these by-products through oil regeneration could potentially prolong the lifetime of transformers. Typically, oil regeneration process includes percolation of oil through an adsorbent system followed by a filtration and a degasification process. Various sorbent types such as fuller's earth, alumina, molecular sieves, silica-kaolin-sand mixture are used for the regeneration process. This paper investigates the acid removal performance of a modified alumina based sorbent, against two conventional sorbents i.e. fuller's earth and alumina. It was found that the overall performance of modified alumina was higher than the conventional sorbent materials. Furthermore, all the three sorbent materials showed higher absorption capacity for low molecular weight acids than the high molecular weight acids.