Fractional distillation is a vital process in oil refineries used to separate crude oil into various useful components. This separation is based on the boiling points of different hydrocarbons. This process is critical in transforming crude oil into usable products such as gasoline, diesel, and others.
What is Fractional Distillation?
Fractional distillation is a technique that separates a mixture into its individual components, which differ in boiling points. In the oil industry, it specifically applies to crude oil, transforming it into more useful forms like gasoline, diesel, and others.
The Process
- Heating: Crude oil is initially heated to approximately 350°C in a furnace, turning it into vapour.
- Entering the Distillation Column: The vapour enters a fractionating column, which is strategically cooler at the top and hotter at the bottom.
- Rising and Cooling: As the vapour rises, it cools down. Different components condense back into liquid at different heights within the column due to their varying boiling points.
- Condensation: Components with higher boiling points condense lower in the column, and those with lower boiling points condense higher up.
- Collection: These condensed liquids, known as fractions, are collected at various levels within the column.
Alos Check – Difference between Crude oil and Petroleum
Fractional distillation of Crude oil diagram
Fractions and Their Uses
- Gases: Found at the top of the column; used for heating and in petrochemical plants.
- Gasoline (Petrol): Utilised as car fuel.
- Naphtha: Acts as a feedstock for chemical production.
- Kerosene: Employed in jet fuel and heating.
- Diesel: Drives trucks and buses.
- Lubricating Oil: Ensures smooth functioning of engines and machinery.
- Fuel Oil: Power ships and used in industrial heating.
- Bitumen: Essential for road surfacing and roofing.
Importance of Fractional Distillation
The fractional distillation of crude oil is critical as it efficiently provides a wide range of necessary products from a single source—crude oil. Each fraction has specific applications, making this process indispensable in multiple sectors.
Further Processing
After the initial separation:
- Each fuel may undergo additional refining to eliminate impurities or improve quality.
- Techniques like cracking are employed to break down larger molecules into more useful ones.
Classifying Fractions
Fractions are generally categorised into:
- Light Distillates: Include products like gasoline and kerosene, known for their low boiling points and high volatility.
- Medium Distillates: Comprise diesel and gas oil, utilised in heating and gas production.
- Heavy Distillates: Characterised by high boiling points and includes heavy fuels and oils, which are less volatile.
At the extreme ends:
- Top of the Tower: Contains gases like propane and butane that are too volatile to condense.
- Bottom of the Tower: Holds residuals like bitumen, too dense to rise and requiring further distillation.
