Test: Conventional & Alternative Fuels of IC Engine - 2 - Mechanical Engineering MCQ

Fractional Distillation: Separating Crude Oil
Crude oil, also known as petroleum, is a complex mixture of hydrocarbons that is extracted from the Earth's crust. It is an essential raw material used in the production of various fuels and products. One of the primary processes used to separate crude oil into its different components is fractional distillation.

What is Fractional Distillation?
Fractional distillation is a physical separation process that relies on the differences in boiling points of the components in a mixture. It is based on the principle that each component in a mixture vaporizes at a different temperature.

The Process of Fractional Distillation:

• 1. Heating: The first step in fractional distillation involves heating the crude oil. The crude oil is heated in a large vessel called a distillation column.
• 2. Vaporization: As the crude oil is heated, it begins to vaporize. The different components of the crude oil have different boiling points, so they vaporize at different temperatures. The vaporized components rise up the distillation column.
• 3. Separation in the Distillation Column: The distillation column is designed with multiple trays or plates. These trays help to separate the different components of the vaporized crude oil.
• 4. Condensation: As the vapor rises up the distillation column, it encounters cooler temperatures at higher levels. This causes the vapor to condense back into liquid form. The components with higher boiling points condense first, while those with lower boiling points remain in the vapor phase.
• 5. Collection of Different Fractions: At different levels of the distillation column, the condensed liquid is collected. The collected liquid at each level represents a fraction, which contains a specific range of hydrocarbon molecules with similar boiling points.
• 6. Separation of Gasoline, Kerosene, and Fuel Oil: The distillation column is designed in a way that the fractions collected at specific levels correspond to the desired products. Gasoline, kerosene, and fuel oil are three important fractions obtained through fractional distillation.
• 7. Further Processing: After fractional distillation, the collected fractions may undergo additional refining processes to obtain the final products with desired specifications. These processes may include further distillation, cracking, reforming, or treatment with additives.

Cracking: Cracking is a process in which larger hydrocarbon molecules present in crude oil are broken down into smaller, more useful molecules. This is achieved by subjecting the crude oil to high temperatures and pressures or by using catalysts. The cracking process is used to produce gasoline, which is a high-demand fuel for automobiles.

Heating: Heating is a general term used to describe the application of heat to crude oil or its components to facilitate separation. In the context of crude oil refining, heating is typically involved in processes like distillation or cracking, where controlled temperature increases are applied to achieve the desired separation or reaction.

Reforming: Reforming is a process that involves rearranging the molecular structure of hydrocarbons present in crude oil. The purpose of reforming is to convert low-octane gasoline components into high-octane gasoline components. This is achieved by subjecting the hydrocarbons to high temperatures and pressures in the presence of catalysts. Reforming

Conclusion: In conclusion, crude oil is separated into gasoline, kerosene, and fuel oil through the process of fractional distillation. This process takes advantage of the different boiling points of the components in crude oil to separate them into distinct fractions. Fractional distillation is a crucial step in the refining of crude oil and allows for the production of various fuels and products that are essential for our daily lives.

Blending amounts of alternative fuel with conventional fuel is one way to displace petroleum. 

Normal paraffins exhibit the poorest antiknock quality when used in an SI engine. The antiknock quality improves with the increasing number of carbon atoms and the compactness of the molecular structure. The aromatics offer the best resistance to knocking in Si engines.

M 0 : Pure gasoline
M 15 :15% methanol and rest gasoline
M 85 :85% methanol and rest gasoline
M 100: Pure methanol

Alcohol does not vaporize as easily as gasoline. Its latent heat of vaporization is much higher. This affects cold weather starting. Gasoline is introduced in the engine to overcome cold weather starting. It helps in quick engine warming.