Fuels and Earth Science: Fractional Distillation

Fractional distillation is a process used to separate a mixture into its component parts, or fractions, such as in the separation of crude oil.
Crude oil is a finite resource found in rocks. It’s a complex mixture of hydrocarbons that can be separated using fractional distillation.
The process of fractional distillation begins with the crude oil being heated until it turns into a vapour.
Once vaporised, it’s sent into the fractional distillation column, which is cooler at the top and hotter at the bottom.
The different fractions in crude oil have different boiling points, so they condense at different levels within the column.
Fractions with a high boiling point condense at the bottom of the column, while those with a low boiling point condense at the top.
The collected fractions are then typically cooled and condensed into liquids, and can be used for various purposes.
Fractions from the distillation process include gases, petrol, kerosene, diesel oil, and bitumen.
Gases have the lowest boiling points, so they stay as gases and are collected at the top of the column.
Bitumen has the highest boiling point so it condenses at the bottom of the column.
Each of these different fractions can be used in different ways in industry. Gases can be used for domestic heating and electricity generation, petrol for car fuel, kerosene as jet fuel, diesel for cars and trains, and bitumen for road surfacing.
The process of fractional distillation is a vital part of the chemical industry, and understanding how it works is important in understanding how resources can be best utilised and managed.