Crude oil, also known as petroleum, consists of a mixture of compounds called hydrocarbons. There are many useful materials that can be produced from it. To be able to do this, it needs to go to refineries for further refining and provide the defined range of products. These refineries normally uses a distillation column to separate crude oils into fraction. This process is called fractional distillation. It is used when separating a mixture of substances with different boiling points.
is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which one or more fractions of the compound will vaporize.
A distillation column with several condensers coming off at different heights is required. It will be heated at the bottom until the crude oil boils. The various components of crude oil have different molecular sizes, weights and boiling temperatures.
Upon heating, the crude oil is evaporated and its vapours will be allowed to condense at different temperatures in the fractionating column. The column is filled with trays or plates that have many holes or bubble caps to allow the vapor to pass through.
As the vapor rises through the trays in the column, it cools.
When a substance in the vapor reaches a height where the temperature of the column is equal to that substance’s boiling point, it will condense to form a liquid. The trays collect the various liquid fractions.
Those substances with high boiling points condense at the bottom and substances with low boiling points condense at the top.
The collected liquid fractions may pass to condensers, which cool them further, and then go to storage tanks, or they may go to other areas for further chemical processing
The main fractions collected generally include refinery gases, gasoline (petrol), naphtha, kerosene, diesel oil, fuel oil, and a residue that contains bitumen. These fractions are mainly used as fuels, although they do have other uses too.
Very few of the components that comes out of the fractional distillation column are ready for market. Some more complex chemical processes will need to take place to break or combine different compounds to produce the required result of the end products.
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Photo credit to BBC.CO.UK