In its natural state, right after being extracted, crude oil is very rich in different components such as hydrocarbons with different molecular weight, and organic compounds.
The refining that follows the extraction is simply the process whereby these substances are separated and made suitable for energy production.
The first substance to be eliminated from crude oil is salt, as it can be highly corrosive to the petrochemical plant.
In the following phase, crude oil is heated at very high temperatures and sent to the base of a fractionating column, where a first separation takes place.
While crude oil moves from the base of the column upwards, it splits into different components, starting from those with the highest molecular weight and boiling point, in the following order: diesel, kerosene and naphtha.
This phase is - more appropriately – called “fractioning” instead of “refining,” because the different components are separated using temperature ranges rather than specific boiling points. The oil derivatives are still not pure enough to be effective, and will need to be refined through more distillations.
The type of distillation we described above is composed of different phases, and takes place inside a single column, which in turn has a complex structure, with different entry and exit points to allow the crude oil to be reinserted for a better efficiency of the process.