Petroleum refining processes are chemical engineering processes which use petroleum refineries to transform crude oil into useful products, such as liquefied petroleum gas, gasoline or petrol kerosene, jet fuel, diesel oil and fuel oils. Petroleum refineries are large industrial complexes that involve many different processing units and auxiliary facilities such as utility units and storage tanks. Each refinery is unique and has its own arrangement and combination of refining processes largely determined by the refinery location, desired products and economic considerations.
The primary end-products produced in petroleum refining may be grouped into four categories: light distillates, middle distillates, heavy distillates and others. Light distillates include, light petroleum gas, gasoline, kerosene, and jet fuel and other aircraft fuel. Middle distillates include automotive and rail-road diesel fuels, residential heating fuel, and other light fuel oils. Heavy distillates include heavy fuel oils, and bunker fuel oil and other residual fuel oils. Other products produced in all petroleum refineries include speciality petroleum naphtha, speciality solvents, petrochemical feed-stocks, asphalt and tar, petroleum coke, lubricating oils, waxes and greases and carbon black.