, INDE X
. 3.1. FUELS INTRODUC TION
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\I_ ' 3.2. SOLID FUELS
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3.3. LIQUID FUELS
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,, 3.4. GASEOUS FUELS
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3.5. COMBUSTIO N I
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, UNIT III
FUELS AND COMBUSTION
3.1 FUELS-INTRODUCTION
Fuel is a combustible substance, containing carbon as a main constituent, which on proper
burning gives large amounts of heat, which can be used economically for domestic and industrial purpose.
Example:
Wood, charcoal, coal, kerosene, petrol, diesel, producer gas, oil gas etc.
During the process of combustion of fuels, the atoms of carbon, hydrogen, etc., combine
with oxygen with liberation of heat simultaneously.
The combustion reaction can be explained as
C+02 ~ CO2 + 94 kcals
2H2 + 0 2 ~ 2H2 0 + 68.5 kcals
The calorific value of a fuel depends mainly on the amount of carbon and hydrogen. In the
process of combustion, the chemical energy of fuel is converted into heat energy. To utilize the energy of
fuel in most usable form, it is required to transform the fuel from its one state to another, i.e. from solid to
liquid or gaseous state, liquid to gaseous state, or from its chemical energy to some other form of energy via
single or many stages. In this way, the energy of fuels can be utilized more effectively and efficiently for
vanous purposes.
REQUIREMENTS OR CHARACTERISTICS OF A GOOD FUEL
A good fuel should have the following characteristics:
1. High calorific value.
2. Moderate ignition temperature.
3. Low contents of ash or non-combustible matters.
4. Low moisture content.
5. Free from objectionable and harmful gases like CO, SOx, H2 S.
6. Moderate velocity of combustion.
7. Combustion should be controllable.
8. Easy to transport and readily available at low cost.
, 3.1.1 CLASSIFICATION OF FUELS
Fuels may broadly be classified in two ways, i.e.
A. According to the mode of their procurement(occurrence)- natural and artificial.
B. According to the physical state in which they exist in nature - solid, liquid and gaseous
A.CLASSIFICATION OF FUELS BASED ON THEIR OCCURRENCE
Fuels are classified into two types as follows:
1. Primary fuels(Natural fuels): It occurs in nature.
Ex., coal, petroleum, gas.
2. Secondary fuels(Artificial fuels): It is derived from primary fuels.
Ex., coke, gasoline, coal gas.
B.CLASSIFICATION OF FUELS BASED ON THEIR PHYSICAL STATE
Both primary and secondary fuels may be further classified into three types :
1. Solid fuels - coal, coke, charcoal
2. Liquid fuels - gasoline, diesel
3. Gaseous fuels - coal gas, natural gas, producer gas, water gas
Fuels
Prum,:u y o:r: Seic,o n,dlary o :r
N atur.al Fuels Artificial Fu els
S olid! Fuels Llqmd Foos G aseous: F u -els
ElL, Wo,o d., coa1 Ex_, P e u:ol1e 1LBTI 00 Ex_, N .a tw:a] gas
□
Solid Fuels. Liquid Foos Ga!:-eous. F uel:!-
Ex... Charm aL Ex _, die s el,. Ex-. LPG.. ~ te:r·
ool::,e ke:r:,o :&ene ga.s
. 3.1. FUELS INTRODUC TION
j/
/ ~,··
\I_ ' 3.2. SOLID FUELS
;.i ~,
i
I
')
.A i, / ,..,,
,V&-.
l.~ ¥'
3.3. LIQUID FUELS
(?'
t(:'
,, 3.4. GASEOUS FUELS
I •
I I
..
if
' ·.~
3.5. COMBUSTIO N I
~~--
-~
-..... ,
...
:t«ll
, UNIT III
FUELS AND COMBUSTION
3.1 FUELS-INTRODUCTION
Fuel is a combustible substance, containing carbon as a main constituent, which on proper
burning gives large amounts of heat, which can be used economically for domestic and industrial purpose.
Example:
Wood, charcoal, coal, kerosene, petrol, diesel, producer gas, oil gas etc.
During the process of combustion of fuels, the atoms of carbon, hydrogen, etc., combine
with oxygen with liberation of heat simultaneously.
The combustion reaction can be explained as
C+02 ~ CO2 + 94 kcals
2H2 + 0 2 ~ 2H2 0 + 68.5 kcals
The calorific value of a fuel depends mainly on the amount of carbon and hydrogen. In the
process of combustion, the chemical energy of fuel is converted into heat energy. To utilize the energy of
fuel in most usable form, it is required to transform the fuel from its one state to another, i.e. from solid to
liquid or gaseous state, liquid to gaseous state, or from its chemical energy to some other form of energy via
single or many stages. In this way, the energy of fuels can be utilized more effectively and efficiently for
vanous purposes.
REQUIREMENTS OR CHARACTERISTICS OF A GOOD FUEL
A good fuel should have the following characteristics:
1. High calorific value.
2. Moderate ignition temperature.
3. Low contents of ash or non-combustible matters.
4. Low moisture content.
5. Free from objectionable and harmful gases like CO, SOx, H2 S.
6. Moderate velocity of combustion.
7. Combustion should be controllable.
8. Easy to transport and readily available at low cost.
, 3.1.1 CLASSIFICATION OF FUELS
Fuels may broadly be classified in two ways, i.e.
A. According to the mode of their procurement(occurrence)- natural and artificial.
B. According to the physical state in which they exist in nature - solid, liquid and gaseous
A.CLASSIFICATION OF FUELS BASED ON THEIR OCCURRENCE
Fuels are classified into two types as follows:
1. Primary fuels(Natural fuels): It occurs in nature.
Ex., coal, petroleum, gas.
2. Secondary fuels(Artificial fuels): It is derived from primary fuels.
Ex., coke, gasoline, coal gas.
B.CLASSIFICATION OF FUELS BASED ON THEIR PHYSICAL STATE
Both primary and secondary fuels may be further classified into three types :
1. Solid fuels - coal, coke, charcoal
2. Liquid fuels - gasoline, diesel
3. Gaseous fuels - coal gas, natural gas, producer gas, water gas
Fuels
Prum,:u y o:r: Seic,o n,dlary o :r
N atur.al Fuels Artificial Fu els
S olid! Fuels Llqmd Foos G aseous: F u -els
ElL, Wo,o d., coa1 Ex_, P e u:ol1e 1LBTI 00 Ex_, N .a tw:a] gas
□
Solid Fuels. Liquid Foos Ga!:-eous. F uel:!-
Ex... Charm aL Ex _, die s el,. Ex-. LPG.. ~ te:r·
ool::,e ke:r:,o :&ene ga.s
