Crude Oil and Fractional Distillation

Crude Oil Overview

• Crude oil is a fossil fuel that serves as a mixture of various compounds, predominantly hydrocarbons (compounds made of hydrogen and carbon).

• The predominant type of hydrocarbons found in crude oil are alkanes.

• Crude oil originates from the remains of ancient plankton and other organic matter that have been buried under mud and subjected to high temperatures and pressure for millions of years.

• Due to its long formation process, crude oil is a finite resource, categorized as a non-renewable fuel.

Extraction and Processing

• Crude oil is extracted from underground sources by drilling into rock formations where it has been stored.

• Once extracted, different hydrocarbons need to be separated to utilize their various properties effectively.

Fractional Distillation

• The process of separating crude oil into its components is called fractional distillation.

• This technique relies on the different boiling points of hydrocarbons.

• Procedure:

  • The crude oil is heated until it converts most of it into gas.

  • The gas mixture is fed into a fractionating column, which is hotter at the bottom and cooler at the top.

Vapor Rise and Condensation

• Gases rise through the column and when they encounter a cooler region below their boiling point, they condense into liquids.

• Longer-chain hydrocarbons have higher boiling points and will condense earlier in the column:

  • Examples:

    • Bitumen: utilized for road surfacing.

    • Heavy fuel oil: further separated for heating or lubricating purposes.

Shorter-Chain Hydrocarbons

• Shorter-chain hydrocarbons have lower boiling points and will rise higher in the column before condensing:

  • Examples:

    • Diesel and petrol: used in vehicles.

    • Kerosene: utilized in jet engines.

• Some hydrocarbons, like liquefied petroleum gas (LPG), remain as gases because their boiling points are lower than the entire column temperature.

Comparison of Hydrocarbon Fractions

• Fractions obtained from fractional distillation can be categorized by their chain length:

  • Top fractions (short-chain): more flammable, making them ideal as fuels.

  • Bottom fractions (long-chain): often poor fuels, used for other purposes or can be broken down through cracking (described in the next video).

Petrochemicals

• All substances obtained from crude oil are known as petrochemicals and serve as raw materials in the petrochemical industry.

• Common products from petrochemicals include solvents, lubricants, polymers, and detergents.

Conclusion

• Fractional distillation is a crucial process for separating crude oil into usable components, each with distinct properties and applications.