Students’ Reading Material
• Introduction to Fuel
A fuel is a substance that has energy stored inside it. So, a substance that produces useful energy when it undergoes a chemical reaction is called as a fuel. Upon burning a fuel, a large amount of energy is released as heat. Fuels are used for various purposes such as cooking food, running vehicles, generating electricity etc. Coal, wood, petrol, diesel etc. are some common fuels. Thus, a fuel can be defined as a substance that produces heat and light energy upon burning in air or oxygen.
• Characteristics of an Ideal Fuel
An ideal fuel should have the following characteristics: o An ideal fuel should have high calorific value. o It should have a moderate ignition …show more content…
Common Varieties of Coal
There are four common varieties of coal-
Anthracite Different Varieties of Coal
Each variety of coal has a different calorific value. The calorific value of different kinds of coal depends upon its carbon content. The higher the carbon content, higher is the calorific value of the coal. The calorific values of different kinds of coal are given in increasing order as:
Peat < lignite < bituminous < anthracite
Peat has the lowest content of carbon as it is the recently buried organic matter. Due to less effect of heat, temperature and pressure, peat gathers less carbon and energy content. With the passage of time, temperature and pressure increases on the coal which forms lignite, bituminous and anthracite eventually. Peat and lignite are the low quality coal types while bituminous and anthracite; both the types of coal have more carbon and energy content. Anthracite is considered the best type of coal. Figure 1: Formation of different types of coal
Table 1: Types of Coal
Type of Coal Carbon Content Calorific Value (kJ/g)
Peat 50-60% 10.5-14.63
Lignite 60-70% 14.63-18.81
Bituminous 75-80% 31.35-33.44
Anthracite 90-95% 28.01-31.35
ii. Products Obtained by Destructive Distillation of …show more content…
During destructive distillation of coal, pure carbon in the form of coke is obtained during the destructive distillation of coal. Coke is used as a reducing agent and a fuel as well. Figure 2: Destructive Distillation of Coal
o Crude Petroleum
Petroleum is a mixture of hydrocarbons that occur in gaseous, liquid or solid form. The term crude petroleum is often used for the liquid form which is called crude oil. Dead marine plants and animals which once lived at the bottom of the sea led o the formation of petroleum. Their remains were covered by layers of sand and mud. With an increase in temperature and pressure, the remains slowly changed into crude oil.
i. Refining crude Petroleum
Petroleum is obtained from oil deposits by drilling a hole using oil rigs in the earth’s crust. After extraction, the crude petroleum is refined in refineries by the process of fractional distillation. The different constituents of petroleum obtained by fractional distillation are called fractions.
ii. Products Obtained by Refining crude