The process of separating oil from fuel isn't typically how the refining process works, since "fuel" itself is made from oil. Instead, crude oil is separated into different types of fuels (and other products) using a method called fractional distillation.
Understanding Fractional Distillation
Fractional distillation is a core process in oil refineries. It works by using the different boiling points of various hydrocarbon chains in crude oil. Here's how it works:
- Heating Crude Oil: Crude oil is heated to very high temperatures, causing it to vaporize.
- Entering a Fractionating Column: The hot vapor is then fed into a tall column called a fractionating column. This column is hotter at the bottom and cooler at the top.
- Condensation: As the vapor rises in the column, it cools. Different hydrocarbons condense into liquids at different temperatures and heights within the column.
- Collecting Fractions: These liquids are collected at different levels of the column. These different liquids are known as "fractions."
Common Products Obtained through Fractional Distillation
| Fraction | Boiling Point Range (°C) | Common Use |
|---|---|---|
| Refinery Gases | Below 20 | Fuel for heating and in chemical plants |
| Gasoline (Petrol) | 20-150 | Fuel for cars |
| Naphtha | 70-170 | Chemical feedstock and making other products |
| Kerosene | 150-250 | Fuel for jets and heating |
| Diesel Oil | 250-350 | Fuel for vehicles and some heating systems |
| Fuel Oil | 350-400 | Fuel for ships, power stations |
| Bitumen/Residue | Above 400 | Road surfacing and roofing |
Key Concepts
- Hydrocarbon Chains: Crude oil is composed of different lengths of hydrocarbon chains. Shorter chains have lower boiling points, while longer chains have higher boiling points.
- Distillation: This is the process of separating components of a liquid mixture by their boiling points.
- Fractions: These are the different liquids collected during fractional distillation, each containing a different mix of hydrocarbons with similar boiling points.
Refining Process
The fractional distillation process does not just separate compounds; it may also join or split the various hydrocarbon chains to create different petroleum products. This means that refineries don’t just separate; they also convert some fractions into others to obtain the most desired end-products.
Therefore, the process described is not so much about separating oil from fuel (as fuels are made from oil), but about separating the components of crude oil into different useable fuels.
