0 Fossil fuels and classification

FUELS & COMBUSTION
Fossil fuel-
? Fuel can be defined as a combustible substance which contains carbon as its main
components, which gives large amount of heat on proper burning.
? Carbon can be used economically for domestic and industrial requirements.
? Common example involving wood, charcoal, coal, kerosene, petrol, diesel, producer gas,
oil gas, etc.
? During combustion process of a fuel (like coal), the atoms of carbon, hydrogen, etc.
combine with oxygen with the simultaneous release of heat at a speedy rate.
? This energy is released due to the "rearrangement of valence elections" in these atoms,
resulting in the formation of new compounds like methane and water.
FUEL + OXYGEN ---> PRODUCTS + HEAT.
? Coals and petroleum oils are the main source of the fuel; the available quantity of these
sources is reduced day by day.
? Fossil fuels are composed by natural resources such as anaerobic decomposition of buried
dead organisms.
? The age of the organisms and their resulting fossil fuels is more than millions of years.
? They are non-renewable resources because they take thousands of years to form, and
reserves are being decomposed much faster than new ones are being made.
? Its uses and production raise environmental issue.
Classification:
1. Solid fuel
? Solid fuel is defined as raw materials which are used as a primary fuel to produce energy
and provide heating.
? Common example under this category includes wood, charcoal, peat, coal, Hexamine fuel
tablets, and pellets made from wood, wheat, rye and other grains.
? It also used in solid fuel rocket technology.
? For creating fire, it has been used.
? Coal is used for firing furnaces, to running steam engines.
? Steam locomotives engines are operated by using wood as fuel.
? In electricity generation, peat and coals are used.
? Due to unsafe levels of toxic emissions, use of some solid fuels is restricted or prohibited
in some urban areas.
2. Liquid Fuel
? Liquid fuels are defined as combustible or energy-generating molecules which are used to
produce mechanical energy.
? Fumes of these fuels are flammable instead of the fluid.
? Most liquid fuels which are used for various purpose in now days, are derived from
petroleum.
Types of liquid fuel:
Gasoline
? It is a by-product of petroleum, contains carbon and hydrogen.
? Gasoline or petrol is produce by hydrocarbon molecules forming aliphatic compounds, or
chains of carbons with hydrogen atoms attached.
? Engines that use unleaded gasoline releases fewer hydrocarbons, have fewer combustion
chamber deposits, and provide a longer life for spark plugs, exhaust system and
carburetors.
? It is generated by distillation of crude oil.
? The desirable liquid is taken out from the crude oil in refineries.
? For the formation of gasoline, petroleum must first be removed from crude oil.
? Gasoline itself is actually not burned, but the fumes it creates ignite.
Diesel fuel
? It is a mixture of aliphatic hydrocarbons extracted from petroleum.
? Diesel may cost less than gasoline; it costs less for production because the extraction
processes used are simpler.
? It can hold dirt particles in suspension longer than gasoline because it is heavier and more
viscous.
? Its efficiency varies with the type of engine.
? Use of a polluted fuel or an improper grade of fuel can cause hard starting, incomplete
combustion, and a Smokey exhaust.
Kerosene
? Kerosene is defined as flammable hydrocarbon oil usually obtained by distillation of
petroleum and used as a fuel, solvent, and thinner.
? It is sometimes used as an additive in diesel fuel to prevent gelling or waxing in cold
temperatures.
? Heat of combustion of kerosene is similar to that of diesel
? It is generally used for heating and fueling vehicles.
3. Fuel gas
? Fuel gas can be referred to any of several gases burned to produce thermal energy.
Natural gas (methane) is the most common example of fuel gas, others include:
? Coal gas or Town gas
? Syngas
? Mond gas
? Propane
? Butane
? Regasified liquefied petroleum gas
? Wood gas
? Producer gas
? Water gas
? HCNG