Liquid Fuels

Almost all the commercial liquid fuels are derived from natural petroleum (or crude oil). The liquid fuels consist of hydrocarbons. The natural petroleum may be separated into petrol or gasoline, paraffin oil or kerosene, fuel oils and lubricating oils by boiling the crude oil at different temperatures and subsequent fractional distillation or by a process such as cracking. The solid products like vaseline and paraffin wax are recovered from the residue in the still.

The following are some important liquid fuels :

1. Petrol or gasoline. It is the lightest and most volatile liquid fuel, mainly used for light petrol engines. It is distilled at a temperature from 65° to 220° C.

2. Kerosene or paraffin oil. It is heavier and less volatile fuel than the petrol, and is used as heating and lighting fuel. It is distilled at a temperature from 220° to 345° C.

3. Heavy fuel oils. The liquid fuels distilled after petrol and kerosene are known as heavy fuel oils. These oils are used in diesel engines and in oil-fired boilers. These are distilled at temperature from 345° C to 470° C.