Crude Oil Refining and Fractional Distillation

Study Notes

Crude oil is a fossil fuel formed from the decomposition of ancient organisms.
It is a complex mixture of hydrocarbons.
It is extracted from the ground or sea and exists as a thick, black, viscous liquid.
It is found in large quantities in various countries.
Crude oil is not directly useful in its natural form; it needs processing.

Fractional distillation is a process used to separate crude oil into its components (fractions).
The separation is based on the different boiling points of the hydrocarbons.
Oil is heated to vaporize the hydrocarbons.
Gaseous components rise up the fractionating tower.
As they rise, the temperature decreases.
Lighter hydrocarbons reach their boiling point first, condense and are collected at lower points in the tower.
Heavier hydrocarbons condense and collect at higher points in the tower.
The lighter hydrocarbons (low boiling point) are collected at the top of the tower, while heavier components (high boiling point) are collected at the bottom.

Different fractions have different uses.
Lighter fractions (e.g., LPG, gasoline) are used as fuels.
Medium fractions (e.g., kerosene, jet fuel) are also used as fuels.
Heavier fractions (e.g., lubricating oils, bitumen) are used in various industrial applications.

Some hydrocarbons are too heavy for desired uses
These can be broken down into smaller molecules through thermal or catalytic cracking
Cracking increases the yield of more useful fractions.

The tower is tall and consists of several trays.
Temperature decreases as you move up the tower.
The temperature at which crude oil enters the towers is high, which causes components to boil.
The crude oil vapors move upward.
Vapor will cool as they rise in the column.
Each component will condense at their respective boiling point.
Components at the top of the tower have lower boiling points;
Components at the bottom have higher boiling points.