This document provides information on various types of fuels including their classification, composition, and uses. It discusses natural/primary fuels like wood, coal, petroleum and natural gas. It also describes artificial/secondary fuels produced from primary fuels such as coke, kerosene, petrol and diesel. Liquid fuels mainly come from petroleum and its distillation fractions. Gaseous fuels discussed include natural gas, water gas, producer gas, biogas, LPG and CNG. The characteristics of good fuels and fuel values are also summarized.

2. Dr. SURENDRAN PARAMBADATH
(M.Sc, M.Phil, M.Tech)
Formerly: Post Doctoral Research Associate,
Nano-Information Materials Research Laboratory,
Pusan National University, Busan-South Korea
Currently: Assistant Professor
Govt. Polytechnic College, Perinthalmanna

3. Any substance which on proper burning in air gives amount
of heat, that can be used economically for domestic and
industrial purposes.
Classification of fuels:
A. Based upon their occurrence or preparation
(i) Natural or primary fuels-which occur in nature ie available in
nature and can be used directly.
Eg: Wood, charcoal, Peat, Lignite, bituminous coal, anthracite coal,
petroleum and natural gas.
(ii) Artificial or secondary fuels which are manufactured artificially,
generally from primary fuels.
Eg: Coke, kerosene oil, Petrol, Diesel oil, Coal gas, water gas,etc…
B. Based upon their physical state, there are
(i) Solid fuels (ii) Liquid fuels and (III) Gaseous fuels.

4. Classification of fuels
Type of Fuel Primary (Natural) Secondary
(Artificial)
1) Solid Wood, Wood, Charcoal, Coke,
charcoal, Peat, Charred
Lignite, bituminous peat, Coal
coal etc. briquette.
2) Liquid Crude Petroleum Various fractions
of petroleum.
3) Gaseous Natural gas Coal gas, Oil gas,
Water gas,
Producer gas,
Gobar gas etc.

5. The calorific value of a fuel is defined as the
quantity of heat liberated by the complete
combustion of a unit mass of the fuel in air or
oxygen with the subsequent cooling of the products
of combustion to the initial temperature of the fuel.
The presence of moisture in the fuel will reduce its
calorific value.

6. Characteristics of a good fuel
1 High calorific value which determines the amount of heat
produced and temperature attained.
2 Moderate ignition temperature.
3 Moderate velocity of combustion for continuous supply of
heat.
4 Low moisture content. Velocity of combustion in presence of
moisture leads to low temperature.
5 Low non-combustible matter content, as their presence lead
to formation of ash, decreases in calorific value of fuel,
additional cost of storage handling of disposal of waste
products etc.

7. Liquid Fuels
The main source of liquid fuel is petroleum, which
on distillation gives important liquid fuels petrol,
diesel and kerosene oil.
Petra = rock, oleum = oil.

8. Treatment of Petroleum
Remove dirt, water sulphur etc.
Fractional distillation
Heating up to 400oC in an iron
retort, whereby all volatile
constituents except the residue are
evaporated, and fractionally
separated during condensation.

9. Crude Oil

10. Super Unleaded Leaded
Unleaded Diesel
Petrol Petrol
Petrol

11. 1. Gasoline or Petrol or Motor Spirit.
It is a mixture of low boiling (40-120oC)
hydrocarbons such as
pentane, hexane, heptane and octane.
Petrol and alcohol in the ratio o 4:1
gives Power alcohol.

12. CH3-CH2-CH2-CH2-CH3
Pentane
CH3-CH2-CH2-CH2-CH2-CH3
Hexane
CH3-CH2-CH2-CH2-CH2-CH2-CH3
Heptane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Octane

13. 2. Kerosene oil
It is a mixture of higher hydrocarbons such
decane to hexadecane.
It is used as a domestic fuel in stoves, as jet
engine oil and for making oil gas.

14. CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Decane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Dodecane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Didecane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Tridecane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Tetradecane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Pentadecane
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Hexadecane

15. 3. Diesel oil
It is a mixture of hydrocarbons with boiling
range (250-320oC).

16. Knocking
The metallic sound produced during irregular
burning of the fuel is termed as knocking.
Straight chain alkane> branched chain alkane>
Olefines> Cycloalkane> Aromatic hydrocarbons

17. Octane Number
The octane number of a fuel is a
measure of its tendency to knock;
when burnt in a spark-ignition engine.
n-hptane ----------Maximum knocking
Octane number 0
Iso-octane -----------Minimum knocking
Octane number 100
Tetraethy lead or Diethyl telluride: Anti knocking agents.

18. Cetane Number
It a measure of the ignition quality ie the
antikonocking character of a diesel oil.

19. Cracking
It is the process of breaking up of less
volatile bigger molecule of hydrocarbons
from petroleum into more volatile lower
molecules of hydrocarbons.

23. 1. Thermal cracking
Fuel oil and lubricant oil are subjected to high
temperature pyrolysis at about 770K and high
pressure, when random cleavage of carbon-
carbon bonds takes place and lower alkanes
result.
A-A-A-A-A-A-A- A-A-A A-A-A + A-A-A-A + A-A-A-A-A-A-A

24. 2. Catalytic cracking
In this process heating is done at a lower
temperature in presence of catalysts silica
and alumina mixture to produce gasoline.

26. 1. Natural Gas
It is formed by the decomposition of organic matter under the
earth and is almost always present in petroleum wells.
Composition:
CH4 = 71%, C2H6 = 5-10% , H2 = 3%, CO + CO2 = rest
It is a cheap convenient fuel and burns with a
hot blue flame.

27. Uses:
1.It is an excellent fuel for domestic and
industrial purpose.
2.Manufacture of a number of chemicals by
synthetic process.
3.As a raw material for the manufacture of
carbon black.
4.In preparation of synthetic proteins by
microbiological fermentation of methane
(CH4)

28. 2. Water Gas
It is a mixture of combustible gases CO and H2
with small amounts of non-combustible CO2 and
N2.
Water gas can be made by passing steam and a
little air alternatively through a bed of red hot
coal or coke maintained at a temperature of
about 900-1000oC in a reactor.
C + O2 CO2
2C + O2 2CO

29. Uses:
1.As a fuel gas
2.As an illuminating gas
3.As a source of hydrogen gas
4.In manufacture of ammonia
gas.
Combination of water gas:
CO = 41%, H2 = 51%, CO2 = 4.2%, N2 = 3%, CH4 = 0.8%

30. 3. Producer Gas
It is a mixture of CO and N2 and is
prepared by blowing controlled amount
of air through a deep bed of red hot coke
or coal, maintained at about 1100oC in a
special reactor.
Composition:
CO = 30%, N2 = 52%, H2 = 13%, CH4 = 3% and CO2 = 2%

31. Uses:
1.For running gas engines.
2.For heating open-hearth furnace
muffle furnace, retorts etc.
3.As a reducing agent in metallurgical
operations.

32. 4. Gobar Gas (Dung Gas)
Degradation of biological matter by the bacterial
action in the absence of free oxygen produces,
biogas.
Combination of water gas:
CH4 = 50-60%, H2 = 5-10%, CO2 = 30-40%, N2 = 2%

33. Uses:
1.It is mainly used as domestic cooking
gas.
2.As an illuminant in villages
3.As a fuel to run engines.

34. 5. LPG (Liquefied Petroleum Gas)
It is obtained as a by product, during the cracking
of heavy oils and from natural gas.
The main constituents of LPG are n-butane, iso-
butane, propane and butene with little or no
propene and ethane.

35. Uses:
1.Mainly as a domestic fuel for
burning gas stove in houses.
2.As a fuel in some of the
industries.
3.As motor fuel.
4.In laboratories in gas burners
for heating purpose.

36. Advantages of LPG
1.Easy to operate, to control and easy to
store.
2.Higher efficiency and heating rate.
3.No smoke and hence neat, clean and no
pollution.
4.Easy to transport, undergoes complete
combustion.
5.Cheaper than gasoline, as a motor fuel.

37. 6. CNG (Compressed Natural Gas)
It is highly compressed form of natural gas. It
consists of methane and may contain small
amounts of ethane and propane.
Uses:
1. In commercial vehicles such as taxis, truck, buses.
Disadvantage:
1. Mainly maintaining at high pressure.
2. The release of methane gas through pipe line
during transport and from vehicles due to its
incomplete combustion.

40. 1. Wood
2. Charcoal
Charcoal is a black porous brittle solid which can burn in air
to give CO2 and traces of CO. It is the most active form of
carbon and a good adsorbent.
3. Peat
The progressive transformation of wood to anthracite under
the earth, due to excessive pressure, high temperature, absence
of oxygen, presence of bacteria and time.
Wood Peat Lignite
Anthracite Coal Bituminous Coal

42. 4. Lignite
It is soft, dark brown colored variety,
representing second stage in the conversion of
vegetable matter into coal.
C= 67%, H = 6%, O = 35% and Ash = 2.5%
Uses: i) Lignites are usually dried, powdered
and pressed into small briquettes and burnt as
house hold fuels and for steam raising boiler
fuel,
ii) Most important use is in manufacture of
producer gas.

44. 5. Bituminous Coal
It is the third stage of conversion of vegetable
matter into coal.
C= 75-88%, H = 5%, O = 2 % and Ash = 10%
Uses:
1.Widely used as a domestic fuel.’
2.In several industries for making
metallurgical coke, coal gas and for steam
raising.

46. 6. Anthracite Coal
It is a class of highest rank coal, the last one in the
formation of coal from vegetable matter. It is the
hardest of all kind of coal.
It is dense, black and brittle.
C= 90%, H = 3%, O = 2 % and Ash = 5%
Uses:
1. As a fuel for house hold purposes
2. For steam raising
3. In metallurgical purposes, where high local heat
and no smoke are desirable.

48. Nuclear Fuels

49. Otto Han discovered the fission
of Uranium opened the
prospects of using the vast
energy stored in the atomic
nucleus for the production of
electric power.
1 Kg of Uranium = 3x106 Kg of high grade coal.

50. Mass Defect and Nuclear Energy
A B + C
High Mass Low mass
Difference is called Mass defect. That
difference is the loss of mass during the
formation of the nucleus of the isotope or the
actual loss of mass equivalent to the energy
released during the formation of the given
nucleus from individual nucleons.

53. Main Parts of a Typical Nuclear Reactor
1. Reactor core: Consists of an assemblage of fuel elements, control rods,
coolant and
moderator. The fission chain reaction takes place in this part of the
reactor and heat energy is liberates.
2. Reflector: To reflect back some of the leaking neutrons.
3. Pressure Vessel: Which encloses the core and reflector.
4. Shielding: To weaken the Y-rays and radiations coming out from the
reactor.
5. Heat Exchanger: To transfer the heat liberated from the reactor core to
boil water and get steam.
6. Turbine: To operate utilizing the steam from the heat exchanger, and to
drive a generator to produce electricity.
7. Moderators: Used are graphite or beryllium or heavy water. Reduce the
KE of fast fission neutrons.
8. Control roads: Boron, steel or cadmium to absorb some neutrons.
9. Coolants: Used ordinary water, heavy water, liquid metal like sodium,
organic liquids and gases. They remove heat from the reactor.

55. Nuclear Fusion
Nuclear fusion is the process of combination of light
weight nuclei to form heavier nucleus, with the
simultaneous release of energy.

56. Advantageous Over Fission Reaction
1.Much greater amount of energy.
2.Products of fusion are non
radioactive while fission products
are unstable and radioactive and
hence fission products pose a
waste-disposal problem.

57. Rocket Propellant
Fuels used in rockets for their propulsion are called
propellant.
1.Solid Propellant
2.Liquid Propellant
3.Hybrid propellant

58. Solid Propellant
The first mankind Propellant.
Modern Solid Propellants are divided in to two classes.
A. Composite propellant
Consists of a blend of polyurethane or
polybutadiene as fuel and ammonium
perchlorate as oxidizer. Along with some
finely divided Al or Mg.
B. Double base propellant
Consists of nitroglycerine and
nitrocellulose, both containing the oxidizer
and fuel element in the same molecule.

59. Liquid Propellant
A. Monoliquid propellant: Consists of a single of a
single liquid chemical compound, which on
decomposition or ignition gives out a large volume of
hot gases.
Eg: Hydrazine, Methyl nitrate, nitro methane and
hydrogen peroxide.
B. Biliquid propellant: Consists of a combination of
liquid fuels like kerosene, alcohol, liquid H2 or
hydrazine and liquid oxidizer like liquid oxygen,
dinitrogen tetroxide or nitric acid.

60. Hybrid Propellant
It consists of a solid fuel and a liquid
oxidizer.
Eg: A mixture of acrylic rubber and
liquid N2O4