Oils used as lubes in machines and equipment, can to a large extent ((30…40 % and more) be collected into special containers of otherwise preserved.
These oils are more or less different from new oil, depending on the conditions of use: use duration, temperature and nature of the lubricated surface. Waste oils from total-loss lubrication systems in closed premises with no dust, are nearly clean or altered chemically.
Waste oils are contaminated by dust, fibers and particles of metal from the friction surfaces. Oils accumulate small carbon particles and water. Oxygen and water participate in various chemical reactions with the hydrocarbons in elevated temperature (oxidation, tar formation etc), which change the properties of the oil. This makes used oil lose its performance and gradually become unusable.
Waste oils usually include motor and industrial oils, as well as a mixture of substances originating from washing pipes, transportation tanks, tankers etc, including those extracted from oil-containing water and oil-based rinsing fluids.
The oil is referred to as waste oil if it has been used for a certain amount of time and/or lost its quality in the course of operation and drained from the oil system.
Waste rinsing fluids are gasoline, kerosene etc no longer usable.
Various equipment is used to collect and change oil. Collection of and careful use of waste oil products makes it possible to conserve oil reserves and protect the environment from pollution.
One of the most realistic ways of replenishing oil resources is regeneration, i.e. restoration of quality and reuse of waste oil. Waste oil regeneration is rapidly developing. It is performed by special equipment.
Waste oil collection should be separate for waste motor oil, waste industrial oil and various mixtures of waste oil products.
The content of usable hydrocarbons in waste oils is quite high. Motor oil regeneration yields 70-85% output of basic oil, depending on the degree of purification and the regeneration process, after which the oil may contain up to 5% of low boiling fractions (gasoline and kerosene as well as volatile gasoil).
The hydrocabon composition of regenerated oil is very similar to that of new oil.
There are various regeneration methods, including multistage processes:
- physical processes including settling, filtration, distillation of fractions, centrifuging, water wash, vacuum evaporation etc;
- physical and chemical, which includes coagulations with surfactants and contact purification with bleaching clay, selective purification with propane, phenol, furan etc;
- chemical methods, which include sulfuric acid process, alkaline process and hydrogentaion.