The separation of crude oil/petroleum products into different chemical compounds can be done by using fractional distillation. Crude oil is a mixture of hydrocarbon of different lengths and sizes. Different hydrocarbon has different chain lengths and hence they have different boiling points. Generally, smaller molecules have less carbon in them and therefore, have lower boiling points. Larger molecules have more carbon in them and hence, they have higher boiling points
By evaporating crude oil, its vapors can be condensed at different temperatures in the fractioning column. Each separated part contains hydrocarbon molecules with a similar or different number of carbon atoms with similar boiling points. A lot of useful materials can be obtained from crude oil using the distillation process.
Process of fractional distillation of crude oil
The process of fractional distillation of crude oil is described below:
- First of all, crude oil is added to a super-heated furnace to boil the mixture, and the temperature of the furnace is maintained at around 600 ºC.
- The boiling crude oil is transferred into a large fractioning column, The lighter gaseous hydrocarbon rises the column. When gaseous hydrocarbon rises the column, it starts to cool, and when the temperature reaches below boiling points, it is converted to a liquid state.
- The fractioning column consists of dozens of distillation trays with lots of small holes.By using these trays, the condensing hydrocarbons are collected and these collected fractions are further treated.
- The solids remaining at the bottom column are called Bitumen, which is large molecules with high boiling points. The lighter gases are collected from the top of column and used as refinery gases. Different chemical substances like fuel oil, diesel, kerosene and gasoline are also collected from different regions of column. These are further purified to remove impurities.
Apparatus of fractional distillation of Crude oil
The following diagram shows the fractional distillation of crude oil.
What is crude oil?
Crude oil is a mixture of hydrocarbon of different lengths and sizes. Different hydrocarbon has different chain lengths.