Describe the steps involved in the fractional distillation of crude oil.

Fractional distillation is a means of splitting crude oil (which is a mixture of a huge range of hydrocarbons in varying amounts) into its fractions (mixtures of hydrocarbons with very similar chain lengths). This is important because different fractions have different properties and therefore have different uses - bitumen has a very large number of carbons per molecule, and is used for tarring roads, whereas petrol has a much smaller number (usually around 8 carbons per molecule).
The process works on the basis that different molecule lengths have different boiling points. This is because for a liquid to boil, the intermolecular forces have to be overcome with the input of energy - longer molecules have more points for forces to act on, so more energy is required to separate them. Henceforth, generally, as the hydrocarbon gets longer, its boiling point increases.
In fractional distillation, the crude oil is piped into the bottom of the fractioning tower, where it is vapourised at a tremendous heat. The gas rises up the tower and as the temperature decreases further up (it is set up to have a temperature gradient), the fractions condense at different points and are piped into separate tanks - the longer ones condense closer to the bottom because they have higher boiling points, whereas the shorter ones remain gaseous for a longer time. Some isn't even vapourised at the start, and is piped-off from the bottom to form residue.
I hope this helps.

Answered by DavidOrrell | 2024-06-10

Steps in Fractional Distillation of Crude Oil
Fractional distillation is a method used in oil refineries to separate crude oil into its various components. Here are the steps involved:
Crude oil is heated to high temperatures, around 400°C, at the base of a fractionating column, causing it to vaporize.
The vaporized oil travels up the column and, as it rises, it cools. Different hydrocarbon chains condense at different levels in the column based on their boiling points.
Heavier components, like bitumen, condense at the bottom (temperatures > 350°C), while lighter ones, such as diesel (250-350°C), kerosene (160-250°C), naphtha (70-160°C), petrol (20-70°C), and gases (< 20°C), condense at progressively higher levels where the temperature is cooler.
As the vaporized components reach adequately cooler zones at different heights within the column, they condense into liquids and are collected.
The separated liquids are simpler mixtures of hydrocarbons and other petroleum compounds suitable for various applications, such as gasoline, diesel fuel, and kerosene.

Answered by GuyPearce | 2024-06-24

Fractional distillation separates crude oil into different components based on their boiling points. The process involves heating crude oil, vaporizing it, and allowing it to condense at various heights in a fractionating column. Each fraction is collected for different uses, such as gasoline, diesel, and bitumen.
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Answered by DavidOrrell | 2024-10-01