Fuels and Combustion- Types of fuels

Types of fuels

A fuel, may be defined as a substance (containing mostly carbon and hydrogen) which on burning with oxygen in the atmosphere air, produces a large amount of heat. The amount of heat generated is known as the calorific value of the fuel. Since the principal constitution of fuel is carbon and hydrogen, therefore, it is also known as a hydrocarbon fuel. Sometimes, a few traces of sulphur are also present in it.

The fuels maybe into the following three general forms;

  1. Solids fuels.
  2. Liquid fuels.
  3. Gaseous fuels.

Each of these fuels may be further subdivided into the following two types;

  1. Natural fuels.
  2. Prepared fuels.

SOLIDS FUELS:- The natural fuels are, wood, peat, ignite or brown coal, bituminous coal, and anthracite coal. The prepared solid fuels are wood charcoal, coke, briquettes coal, and pulverized coal.

  1. Wood – It consists of mainly carbon and hydrogen. The wood is converted into coal when burnt in the absence of air. The average calorific value of wood is about 19700 kJ/kg.
  2. Peat – It may be regarded as the first stage in the formation of coal. Its average calorific value is 23000 kJ/kg.
  3. Lignite or brown coal – It represents the next stage of peat coal formation, and is an intermediate variety between bituminous coal and peat. Its average calorific value is 25000 kJ/kg.
  4. Bituminous coal – It represents the next stage of lignite in the coal formation and contains very little moisture (4-6)% and 75-90 % of carbon. The average calorific value of bituminous is 33500kJ/kg.
  5. Anthracite coal – It represents the final stage in the coal formation, and contains 90% or more carbon with a very little volatile of bituminous coal is 33500 kJ/kg.Anthracite coal – present the final stage in the Coal formation and content 90% or more carbon with very little volatile matter. This has a high calorific value of about 36000 kJ/kg and is, therefore, very valuable for steam rising and general power purposes.

    Wood Charcoal – it is made by heating wood with a limited supply of air to a temperature not less than 280 centigrade. It is a good prepared solid fuel that is used for various metallurgical processes.

    Coke – it is produced when a call is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel. This process is known as the carbonization of coal. Coke is Dull black in color and smokeless. It has a high carbon content of about 85 to 90% and has a higher calorific value than coal.
    eat the carbonization aap coal is carried out at 500 to 700 centigrade the resulting cookies scalded lower temperature Coke or soft coke. It is used as a domestic fuel. The hard Coke is mostly used as a blast furnace fuel for extracting pig iron from iron notes to some extent as a fuel in the furnace for producing cast iron.

    Briquetted coal – it is produced from the finally ground cal by molding under pressure with or without a binding material. The briquette coal has the advantage of having practically no loss of fuel through grate opening and thus it increased the heating value of the fuel.

    Pulverized coal – the low great coal with Ash content, is powered people Verizon machines. Apologized cold is really used in the cement industry and also in the metallurgical process.


    Almost all the commercial liquid fuels are dry weight from natural Petroleum. The liquid fuels consist of hydrocarbons. 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 Aur Bi process such as cracking. The solid product like gasoline and paraffin wax recovered from the Residue was in the still.

    Petrol or gasoline – it is the lightest and most volatile liquid fuel mainly used for lightweight all engines. It is distilled at a temperature from 65 degrees To 220 degrees centigrade.

    Kerosene or paraffin oil – is heavier and less volatile fuel than petrol and is used as heating and lighting fuel. 30 distillate at a temperature from 220 degrees To 345 degrees centigrade.

    Heavy fuel oils – the liquid fuels distillate after petrol and kerosene are known as heavy fuel oils. These oils are used in diesel engines and in oil-fired boilers. 20000 distillate at a temperature from 345 degrees to 770 degrees centigrade.


    Channel gas is usually found in or near the petroleum fields under the Earth’s surface. It sincerely consists of Marsh gas or methane together with a small number of other gases such as ethane, carbon dioxide, and carbon monoxide.

    Coal gas – it is also known as town gas. It is obtained by the carbonization of coal and consists mainly of hydrogen, carbon monoxide, and various hydrocarbons. It is very rich in combustion gases. And is largely used in town for street and domestic lighting and heating. It is also used in furnaces and for running gas engines. It is calorific value is about 21000 to 25000 kJ/m3.

    Producer gas – it is obtained by the partial combustion of coal, coke, site coal, or charcoal in a mixed air steam blast. It is mostly used for furnaces people are glass meeting and also for power generation. It is manufacturing cost is low and has a calorific value of about 5000 to 6700 kJ/m3.

    Water-gas – it is a mixture of hydrogen and carbon monoxide and is made by passing steam over incandescent coke. As it burns with a blue flame, also known as Blue Water gas.

    Mond gas- it is produced by passing air and a large amount of steam over West coal at about 650 degrees centigrade. It is used for power generation and heating. It is also suitable for use in gas engines. The calorific value is about 5850 kJ/m3.

    Blast furnace gas – Viper. In the production of Big Island in the blast furnace. Arms as a fuel in steelwork, for power generation in the gas engine for steam rising in boilers and for treating the blast for the furnace. The gas leaving the blast furnace has a high dust content the process of which varies with the operation of the Furnace. It has a low heating value of about 3750 kJ)m3.

    Coke oven gas – is a byproduct from Coke oven and is obtained by the carbonization of bituminous coal. Calorific value varies from 14500 to 18500 kJ/m3. It is used for industrial heating and power generation.

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