FRACTIONAL DISTILLATION OF CRUDE OIL





FRACTIONAL DISTILLATION



FRACTIONAL DISTILLATION

Fractional distillation is the first step of turning crude oil into effectively used petroleum products in the modern industry. During the fractional distillation process crude oil is heated up to 350⁰ C  in order to turn it into a mixture of gases. Its also called the seperation process. This fractional distillation is done at refineries where crude oil is distilled in distillation towers.

Crude oil is a mixture of many types of molecules called hydrocarbons. Crude oil consists of thousands of hydrocarbons which have different numbers of carbon atoms. Their boiling points are so close together that it would be nearly impossible to seperate them individually. But this process is not necessary as crude oil is lumped into groups called boiling fractions where each fraction covers a range of boiling points. Heavier hydrocarbons have greater boiling points and the lighter hydrocarbons have lower boiling points.

The fractional distillation process may differ from refinery to refinery as it depends on the crude oil being distilled. In general before distillation crude oil is heated enough to vaporize some, after it gets to distillation tower/column where it becomes a form of mixture of vapors and liquids. Once the crude oil is inside the distillation tower, the liquids and vapors seperate. The liquids fall to the bottom of the distillation tower and the vapors rise. As they pass through the trays (bubble caps) they are cooled. When their temperature falls below the boiling point of the heaviest fraction this fraction will condense on the tray and will draw off. The rest of the vapors will rise up through this tray to the next where they cool further below the boiling range of the next heaviest fraction and it condensates again. This process continues until the lightest fraction is on the top of the distillation tower and is condensed.

In fractional distillation process liquefied petroleum gas (LPG) forms at the top of the distillation tower. In the next fractions down gasoline, jet fuel and paraffin for lighting and heating, diesel fuels, lubricating oils, waxes and polishes, fuels for industrial use and asphalt and bitumen is formed.