Refining of petroleum, as understood in Class 8 science, is the process of separating crude oil into its various useful components. This separation is crucial because crude oil is a complex mixture of different substances.
Why is Refining Necessary?
Crude oil, as it comes from the ground, isn't directly useful in its raw form. It's a thick, dark liquid containing many different hydrocarbons (compounds made of hydrogen and carbon). Each of these hydrocarbons has a different boiling point. Refining takes advantage of these differences to separate the crude oil into fractions, each with specific uses.
The Refining Process
The primary method used for petroleum refining is fractional distillation, carried out in a petroleum refinery. This process involves the following steps:
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Heating: The crude oil is heated to a high temperature, causing most of it to vaporize.
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Fractional Distillation Column: The hot vapor is passed into a tall tower called a fractional distillation column. This column is hotter at the bottom and cooler at the top.
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Condensation: As the vapor rises through the column, different fractions condense at different heights, depending on their boiling points. Substances with higher boiling points condense at the bottom (where it's hotter), while those with lower boiling points condense higher up (where it's cooler).
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Collection: The different fractions, now in liquid form, are collected separately.
Products Obtained from Refining
The refining process yields a variety of important products, including:
- Petroleum Gas: Used as fuel in homes and industries.
- Petrol (Gasoline): Used as fuel in motor vehicles.
- Kerosene: Used as fuel in stoves, lamps, and jet aircraft.
- Diesel: Used as fuel in heavy motor vehicles and electric generators.
- Lubricating Oil: Used to reduce friction between moving parts of machinery.
- Paraffin Wax: Used in candles, vaseline, and ointments.
- Bitumen: Used in road surfacing and for waterproofing.
Petrochemicals
Many useful substances, called petrochemicals, are obtained from petroleum and natural gas. These are used in the manufacturing of various products such as:
- Detergents
- Fibers (rayon, nylon, polyester)
- Polythene and other plastics
In summary, petroleum refining is a vital process that transforms crude oil into the fuels and materials that power modern society.
