Crude oil is a mixture of different substances and must first be ‘refined’ in a refinery—it must be broken down to its components. For this, it is heated at about 300°C in a distillation set-up. The individual substances evaporate at different temperatures. Petrol, used as fuel in many cars, becomes gaseous at temperatures between 35°C and 140°C, whereas diesel oil becomes gaseous at about 300°C. The different vapours are collected and cooled or liquefied. In this way, the individual components of crude oil are separated from one another and stored as diesel oil, kerosene, or petrol.
