Oil accumulates various oxidation products, contaminants and other undesirable substances in the course of operation. These cause significant deterioration of the oil’s performance and properties. The latter cease to comply with the requirements and the oil then must be changed. To preserve valuable materials, used oils should be regenerated.

Regeneration of oil with crude oil in refineries does not seem possible since the additives present in the oil can disrupt the process. The existing used oil regeneration operations are based on physical and chemical methods, or a combination thereof, and focus on removal of aging products and contaminants from the oil.

Purely physical methods allow to remove various solid particles and microscopic water droplets. Tar and solid residue can be partially removed. High volatile contaminants can be distilled out of the oil. These physical methods include gravity, centrifuge, electric, magnetic, vibration processing, as well as filtering, water washing, evaporation and vacuum distillation.

Settling is the easiest process. It is based on natural settling of solid particles and water under the influence of gravity. Depending on the specifics of the process and the requirements to oil purity, settling may be either the only operation, or a preliminary operation before further filtration or centrifuge treatment. The main drawbacks of this method is its long duration and inability to remove particles smaller than approximately 50 micron.

The essence of filtration is the removal of solid particles and tar by special filters. These are made from paper, felt, metal or plastic mesh, composite materials as well as ceramics. To improve quality of filtration, a multistage filtration system is used: fine filtration follows a number of coarse filters in the system.

The most efficient of the purely physical methods is centrifuge processing. Centrifuges allow to remove water and solid contaminants. This type of purification separates the different fractions of mixes by centrifuge force, as the name implies. This method allows to purify the oil to 0.005% solids and 0.6% moisture by weight.