Oil refinery. This is the furnace where crude oil is heated to 470 degrees Celsius before it enters a distillation tower (still). The furnace burns waste gases from the oil refining process, and uses energy-efficient heat exchangers. Crude oil, which is oil from the ground before it has been refined, contains a mixture of hydrocarbons. This mixture is heated to separate it into parts called fractions. Lighter fractions boil off first and leave the heavier fractions behind. Fractions that are obtained from crude oil include bitumen, fuel oil, lubricating oils, diesel, jet fuel, petrol, and petroleum gases. The fractions are used as fuels, lubricants, and as raw materials for the chemical industry. Photographed at ExxonMobil's Fawley Oil Refinery and Chemical Plant, Hampshire, UK. The oil refinery is the largest in the UK.