Simple distillation involves heating the liquid mixture to the boiling point and immediately condensing the resulting vapors. This method is only effective for mixtures wherein the boiling points of the liquids are considerably different (a minimum difference of 25oC).
steps :
1) Evaporation
Crude oil is heated until it evaporates.
Crude oil vapour is put into a fractionating column at the bottom and rises upwards.
2) Condensation
The temperature is highest at the bottom of the column. Long-chain hydrocarbons condense at the bottom and are collected as liquids.
Short-chain hydrocarbons have lower boiling points. They pass up the column and condense at lower temperatures nearer the top.
3) Collection
The fractions are collected. They are then processed to create end products:
Fuels (e.g. petrol, diesel) are a common end product.
The petrochemical industry can use some fractions as feedstock (material used in an industrial process) to make solvents, lubricants, detergents etc.