TABLE OF CONTENTS Whenever a substance is burnt in air or oxygen with the evolution of heat, the process is called combustion and the substance which is burnt is known as combustible substance. The heat evolved during a combustion can be used economically for industrial or other use. All combustible substances which contain carbon as the main constituent are called fuels. Thus, a fuel may be defined as, any combustible substance, chemical or reactant containing carbon as the main constituent which on proper burning produces heat that can be used economically for domestic and industrial purposes and in generation of power.
The fuels are broadly classified into two types depending upon the state of matter:
Primary Fuels. These include the naturally occurring fuels found freely on earth's crust. These are further classified as:
Solid fuels, for example, wood, peat, lignite, coal, etc.
Liquid fuels, for example, petroleum, crude oil, etc.
Gaseous fuels, for example, natural gas, etc.
Secondary or Derived Fuels. These are artificially manufactured or are derived from primary fuels. These are further classified as:
Solid fuels, for example, coke, charcoal, petroleum coke, pulverised coal, and colloidal fuels. Solid rocket fuels such as thiokol, hydrazine, nitrocellulose, etc.
Liquid fuels, for example, gasoline, diesel oil, kerosene, coaltar and its fractions, alcohol, LPG, and synthetic spirit.
Gaseous fuels, for example, coal gas, water gas, oil gas, biogas, blast furnace gas, acetylenes, etc.
The flowchart for the classification...
