This document discusses combustion principles and provides details on various topics related to combustion. It defines combustion as a chemical reaction between a fuel and oxygen that produces a considerable amount of heat. It also discusses the basic elements required for combustion, different phases and types of combustion, industrial combustion processes and fuels, classification of industrial combustion, and concludes with emphasizing the importance of flames and combustion beds in industrial processes.

1. MEHRAN UNIVERSITY OF
ENGINEERING AND TECHNOLOGY
Jamsher Khan 16CH44 (GL)
Sagar Khan 16CH56
Affaque Bhatti 16CH51
Abdul Manan 16CH15
Waqar Amin 16Ch110
Topic
Combustion Principle
Submitted To
Pro. Dr Shaheen
Department Of Chemical Engineering MUET

2. COMBUSTION PRINCIPLE
 Combustion is a chemical reaction between a
Fuel and Oxygen Which is accompanied by the
production of considerable amount of Heat
 Usually Its an Endothermic Reaction
 The reaction has to be initiated By some Source
Of High Temperature Energy (ignition) l
 Combustion refers to the rapid oxidation results
in large amount of heat is released
 Solid and liquid fuels must be changed to a gas
before they will burn

3. COMBUSTION PRINCIPLE
 Combustion plants are fired by wide
variety of fuels from natural gas
 But common to all is the combustion of
fuels containing the elements are
CARBON and HYDROGEN generally
known as Hydrocarbon Fuels

4. COMBUSTION REACTIONS

5. COMBUSTION PROCESSES
o There are several processes of combustion Of
Fuel
1. Bringing together the fuel and air
2. Ignition the reaction
3. Ensuring that the flame burns in a stable
manner
4. Extracting useful heat from the process
5. Arranging for the Safe disposal of the products
of combustion

6. BASIC ELEMENT OF COMBUSTION
 The fire triangles or combustion triangles
or ″fire diamond″ are simple models for
understanding the necessary ingredients
for most fires.
 The triangle illustrates the three
elements a fire needs to ignite: heat, fuel,
and an oxidizing agent (usually oxygen

7. BASIC ELEMENT OF COMBUSTION

8. PHASES OF COMBUSTION
1.Pre-Ignition
 Heat Is required to raise a fuel to ignition
Temperature (600 degree F)

9. PHASES OF COMBUSTION
2. Ignition
 Process Where A rapid Exothermic reaction
is initiated Which Causes The material to
undergo Changes producing temperature
greatly in excess of ambiet

10. PHASES OF COMBUSTION
3. Combustion
 Flaming =Volatiles that produced in the
preheating phase ignite to form a visible
flame
 Smoldering =The remaining carbon may
burn as a solid surfaces oxidation

11. PHASES OF COMUSTION
4. Extinction
 Opposite of ignition
(termination of combustion)
 Moisture Content of fuel can play a large
role

12. FACTORS THAT WHICH INCREASES THE
COMBUSTION PROCESS
 Flames are brought closer to the Fuel to
Slope
 The wind Pushes The Flames Over wind
 The amount Of time the fire has burnt
 The ventilation characteristic Of the
Confining Structure
 The Amount and Type Of Combustible
Present

13. MODES OF SPREAD OF FIRE
conduction convection Radiation

14. PRINCIPLE OF FIRE/ COMBUSTION
Breaking
Of Chain
Reaction
(It Is the
chemical
reaction)
Smotherin
g
(Cutting off The
supply Of oxygen
from Fire Area )
Starvation
(Removal of
un burnt
Material from
Fire Area)
Cooling
(Removal of heat
from the burning
material Fire)

15. TYPES OF COMBUSTION
Complete
and
incomplete.
Spontane
ous
Micro-
combustio
n.
Stoichiome
tric
combustio
n
Turbulen
t
Smoulderin
g Rapid
Micro-
gravity.
Explosion

16. INDUSTRIAL COMBUSTION
1. General definition
 combustion is defined as the oxidation of fuels,
typically, but not exclusively, through the rapid
combination of hydrogen and carbon contained
in the fuel with the oxygen contained in
atmospheric air
 This rapid combination releases heat at
relatively high temperature, which may then be
used for the heating of industrial processes,
including the generation of steam and high-
pressure hot water

17. INDUSTRIAL COMBUSTION
 This may be very simplistically represented
as:
 2C + O2 2CO + Heat
 2CO + O2 2CO2 + Heat
 2H2 + O2 2H2O + Heat

18. INDUSTRIAL COMBUSTION
2. Industrial Fuels
 An industrial fuel may be a regular fossil fuel
such as coal, crude oil, or natural gas.
 These may be processed from their raw “as
found” state to produce a wide variety of
refined fuels such as blended pulverised coal,
desulphurised coal gas, Liquified Petroleum
Gases (LPGs), liquid fuels ranging from
gasoline through to residual oils and so forth.
 Alternatively the fuel may be derived from
biomass material.

19. INDUSTRIAL COMBUSTION
 Traditional firewood is arguably the
“original fuel” used by mankind.
 Alternatively fuels may be derived from
wastes to produce so-called 'Refuse Derived
Fuels”' or RDFs.

20. INDUSTRIAL COMBUSTION
3. Industrial Comburents
 An industrial Comburent may range from
regular atmospheric air containing
approximately 21% v/v O2,
 The remainder being almost exclusively
molecular nitrogen - N2, through oxygen
enriched air to relatively pure oxygen - Oxygen
containing a very small quantity of impurities.
 Alternatively oxygen depleted (vitiated) air - for
example Gas Turbine or Diesel exhaust gases -
may also be used as a comburent.

21. INDUSTRIAL COMBUSTION
4. Industrial Combustion Modes
 Traditional industrial combustion processes were
primarily based on the concept of the comburent -
almost always, regular atmospheric air - being
encouraged to rise through a bed of fuel
 Originally containing wood but later various forms of
lump coal and most recently, domestic solid waste.
 Such a system is described as a stoker fired boiler of
which there a several basic types. Figure 1 shows an
example of a stoker fired boiler.

22. INDUSTRIAL COMBUSTION

23. CLASSIFICATION OF INDUSTRIAL
COMBUSTION
GasesLiquidsSolids

24. CLASSIFICATION OF INDUSTRIAL
COMBUSTION
1. Solids
 In recent decades such solid fuel combustion
modes, have given way, at least in relatively large
coal fired scale boilers, to pulverised coal burners,
where the coal is milled to a very fine powder -
typically 75% by mass < 75mm
 passed through a burner in suspension in an
atmosphere derived from the coal dryer. This
produces a turbulent diffusion flame, an example
of which is shown in Figure Arrays of such flames
are used to fire boilers of various designs.

25. CLASSIFICATION OF INDUSTRIAL
COMBUSTION

26. CLASSIFICATION OF INDUSTRIAL
COMBUSTION
2. Liquids
 Liquid fuels have been traditionally burned in
various forms of pot burners
 Modern liquid fuel burners employ atomising
devices to produced fine droplets of the fuel
 Which initially are evaporated in the throat of a
burner which gives rise to a turbulent diffusion
flame, an example of which is shown in Figure

27. CLASSIFICATION OF INDUSTRIAL
COMBUSTION

28. CLASSIFICATION OF INDUSTRIAL
COMBUSTION
3. Gaseous
 Finally gaseous fuels are exclusively fired in
burners which give rise to flames.
 These may be produced by premixing the
gaseous fuel and the comburent to give a
'premixed' flame.
 Alternatively the gaseous fuel and the
comburent may be mixed in the burner to give a
regular turbulent diffusion flame, as shown in
Figure

29. CLASSIFICATION OF INDUSTRIAL
COMBUSTION

30. CONCLUSION
 It is clear from the various examples of
combustion given above, that there is a
variety of combustion modes used in
industry.
 Flames are of considerable importance in
industrial process heating and have formed
the basis of the research of the International
Flame Research Foundation for over 50 years
(Ref to Spirit of IJmuiden)

31. CONCLUSION
 However the various form of bed stokers,
particularly fluidized beds, are also of
particular importance in industry.

32. REFERENCES
 Combustion
Handbook
Combustion File no.: 32
Version no.: 1
Date: 16-10-2000
Author: Peter Roberts
Referee: Nick Syred
Sub-editor: Neil Fricker
Source: Author
Domain: Open Domain