combustion equipments

1. COMBUSTION
EQUIPMENTS FOR
FUELS
PRESENTED BY : AMAN GUPTA
RAKESH GUPTA
SWARN VEER SINGH JARAL
DEVIKA BHARDWAJ
ANAM MUKHTAR
SYED RABIA
PANKAJ SHARMA
FUEL TECHNOLOGYTEACHER CONCERNED:
Dr. Ankush Gupta

2. COMBUSTION
 A Fuel is basically a source of heat.
 The usual method of producing heat from fuel is by the
process of Combustion.
 It is a chemical reaction between the Fuel and the
Oxidant.
 Combustion in a fire produces Flame, and the heat
produced can make combustion self-sustaining.

3. COMBUSTION

4. COMBUSTION EQUIPMENTS
For smooth and efficient combustion, there are some
requirements :
 Fresh charge of fuel should be freely ignited as it enters the
burning zone.
 Steady combustion is the basis for obtaining the desired
amount of heat release.
 Adequate combustion space should be provided for driving
the process.

5. Contd.
 Sufficient temperature of the combustion gases should be
maintained.
 Quantity of air supply should is important in achieving proper
combustion.
 The method of air supply is another vital factor of efficient
combustion.
So considering all these requirements, there is a need of a
combustion equipment.

6. Contd.
 Combustion equipments are those appliances that are
used for burning fuels for heating.
 These includes heaters, ovens, stoves, furnaces,
fireplaces, dryers, burners, stokers, and many more.
 Combustion equipments can be used for solids, liquids,
and gaseous fuels.
 These allow the proper combustion of fuels.

7. WHAT IS A BURNER?
Device which enables a chemical reaction of fuel
and oxidizer (usually Oxygen from air) to produce
heat in a controlled way.

8. TYPES OF BURNER :
• GAS BURNERS.
• OIL BURNERS.
• COAL BURNING EQUIPMENTS.

9. Requirements for smooth & efficient
combustion :
• Fresh charge of fuel should be freely ignited as it enters the
burning zone.
• Steady combustion is the basis for obtaining the desired
rate of heat release.
• High temperature combustion is no doubt a fast process
but proceeds with a finite rate.
• The quantity of air supply is important in achieving proper
combustion.

10. Contd…
• The method of air supply is another vital factor of efficient
combustion.
• Sufficient temperature of the combustion gases should be
maintained in all parts of the combustion chamber.

11. Gas burners :
• Numerous types of burners have been developed for
burning gaseous fuels in domestic and industrial heating
appliances. There are two basic types :
• Total or partial premix type, in which a part or whole of the
combustion air is mixed with the gas before it emerges out
of the nozzle.
• Nozzle-mix type, in which, the air is supplied to the burner
tip after the gas leaves the nozzle.

12. Atmospheric or aerated gas burners :
• These burners are based on the principle of the Bunsen
burner.
• The burner consists of a fixed orifice, spud for gas inlet, a
controllable shutter for air supply, a venturi-shaped mixing
tube and a burner head with ports (holes) drilled in it.
• The narrow zone of the mixing tube is called its throat
which diverges into the hind part called its bell.
• The gas is controlled by a valve in the gas line.

13. Contd…
• When the gas is admitted through the orifice, its kinetic
energy is increased owing to the high injection velocity and
creates a low pressure at the throat.
• Primary air is sucked into the bell through the air shutter.
• During flow through mixing tube from the bell to the
burner head the gas and air mix uniformly and the static
pressure is increased by the slowing down of the fluid
stream.

14. Contd…
• The combustible mixture burns in the form of tiny burner
flames anchored on the ports of the burner head.
• The primary air is not enough to complete the combustion.
• Secondary air is entrained on the flame surface from the
surrounding atmosphere.
• The quantity of primary air depends upon the type of
flame, burner design, input rate and type of gas.

15. Atmospheric gas burner
• Depending upon the gas pressure, there may be low
pressure gas aspiration at 7.5 to 20 cm wg or high pressure
gas aspiration at 0.25 kg/cm^2 gauge and above.

16. air aspiration gas burners :
• Air is supplied from a compressor at a medium pressure of
0.15 to 0.35 kg/cm^2 gauge or above and its kinetic energy
is used to aspirate gas at 7.5 to 20 cm wg into an aspirator
body for mixing the two and then the mixture enters the
combustion chamber.
• The gas is supplied at a constant pressure controlled by a
governor.

17. Air aspiration gas burner :

18. Depending upon the structure of the
flame, gas burners are :
• Torch burner : Each burner gives one flame visibly projected
from the burner tip.
• Ring burner : It is usually an atmospheric burner. The
burner head is in the form of concentric rings having
suitably drilled holes.
• Pipe burner : This is also an atmospheric burner. The mixing
tube ends in a pipe with drilled holes or projecting tube
ports. There may be single-or multiple-row drilling.

19. Contd…
• Flameless combustion types : In the surface combustion
system, the combustion is localised on the solid surface and
no flame is visible.
• These systems are often referred to as flameless
combustors.
• Surface combustion is used at both very high and very low
gas velocity which will normally give rise to blow off and
flash-back problems.

20. Contd…
• These burners suffer from the disadvantage of noisy
operation brought about by the combustion progressing as
a series of explosions in rapid succession inside the tunnel.
• Tunnel burners are manifold in groups so that one gas-air
proportioner controls the group.
• The combustion is complete with the primary air supplied.

21. Tunnel burner using the surface
combustion principle :

22. Contd…
• Pulsating combustors : They are in a class by themselves.
The periodic appearance of explosion flames characterize
them.

23. Liquid Fuels
 Liquid materials that are used as a fuel to produce
energy by combustion with oxygen or oxygen-enriched
air are known as liquid Fuels.
 Petroleum accounts for the bulk of the liquid fuels.
 The other liquid fuels in use are coal tar, crude benzol,
synthetic liquid fuels.
 All internal combustion engines run on the liquid fuels.

25. VAPORISING BURNERS
 Vaporising burners are favoured for heating units of small
size such as portable air heaters, small boilers and cooking
stoves for domestic purposes.
 Vaporising burners are characterised by low cost and quiet
operation.
 Suitable for oils ranging from Naphtha to light fuel oil.

26. PRINCIPLE OF OPERATION
 The volatile fuel is passed at a low pressure through a tube
adjacent to the flame, where vaporisation takes place.
 The vapour stream issues out of an orifice at a high velocity and
entrains primary air.
 The fuel-air mixture passes through a mixing tube and burns at
the burner head similar to atmospheric gas burner principle.

27. TYPES OF VAPORISING BURNERS
1) POT TYPE BURNER:
 Common type vaporising burner.
 Capacity upto 10 kg/h.
 Superior Kerosene and liquid fuel oil are used.
Fig: pot – type burner

28. WALL – WIPING FLAME ROTARY
VAPORISING BURNER
 Use coarse atomisation before the
fuel is vaporised.
 Capacity up to 30 kg/h.
 Kerosene and liquid fuel oil are used.
 Premixing of fuel and air .
 Power requirement is low and
operation is noiseless. Fig: wall-wiping flame
rotary

29. HIGH SPEED VAPORISING BURNER
 A high rate of vaporisation is
achieved by atomisation of the
volatile liquid fuel and
recirculation of hot combustion
gases within the burner.
 This burner clearly bears out the
difference between vaporising
and atomising burners. Fig: high speed vaporising burner

30. ATOMISING BURNERS
 What is atomisation ?
“Atomisation is a process of preparing the liquid fuel for
combustion by disintegrating it into droplets. Enormous surface
area per unit weight is created and this helps the heterogeneous
combustion of the liquid fuel and the gaseous oxidant”.
 Atomising burners are provided with an arrangement for the
atomisation of liquid fuels before the actual combustion takes
place.

31. TYPES OF ATOMISING BURNERS
 1) PRESSURE JET ATOMISING BURNER:
Plain orifice type
( used for fuel
injection in diesel
and internal
combustion engines.
Very high pressure s,
upto 350 kg/m2 )
Centrifugal swirl
type

32. SIMPLE SWIRL TYPE OIL BURNER
These burners are most
popular in large industrial oil
burners.
These burners have much
lower oil pressures , 7 to 35
kg/cm2 .
Fig: swirl type oil burner

33. TWIN FLUID ATOMISERS
 These atomisers use an auxiliary fluid ( air or steam) to atomise
the oil and are of three main types:
 A) LOW PRESSURE – type using air at 35 – 70 cm wg.
 B) MEDIUM PRESSURE – type using air at 0.4-1 kg/cm2.

 C) HIGH PRESSURE – type using air / steam at pressures> 1
kg/cm2 gauge.

34. Depending upon whether the fuel and auxiliary fluid mix within the
burner or beyond the burner outlet ,LP , MP and HP types of
atomisers are of following types.
Fig: twin fluid atomisation: a) , b) , c) OUTSIDE MIX TYPES ; d) , e) , f) INSIDE MIX
TYPES

35. ROTARY ATOMISERS
FIG: ROTARY ATOMISING
BURNER
These burners are used in boilers and small installations.
Capacity upto 800 kg/h is available which is much lower than the maximum capacity
of other atomiser types.
Rotary atomising burners are compact , efficient and comparatively low in initial
cost.

36. SOLID FUELS
 Solid materials that are used as a fuel to produce energy
by combustion with oxygen or oxygen-enriched air re
known as Solid Fuels.
 Solid fuels which are present in the nature called
Natural Solid Fuels which includes wood, coal,
charcoal and many more.
 The ones which are man-made or prepared artificially
are called Processed Solid Fuels which includes coke,
briquettes and many more.

37. SOLID FUELS

38. COMBUSTION EQUIPMENTS
Coal (solid fuels) may be burnt by various ways :-
1. Fixed or agitated beds on a grate,
2. Suspension in air in pulverized fuel burners or
cyclone burners,
3. Fluidized bed combustors, in a slurry with water or
in suspension in oil in atomization burners.

39. Contd.
 Grate firing is employed in domestic and industrial
units and in thermal power plants.
 Pulverized fuel and cyclone burners are used in
thermal power stations and large industrial units.
 Fluidized bed are used in refrigeration and for
advanced applications.

40. Fixed Bed Combustion
 Fixed-bed combustion systems include grate furnaces and
underfeed stokers.
 In fixed-bed systems, lumps of coal, usually size-graded
between 3 and 50 millimeters, are heaped onto a grate, and
preheated primary air (called under fire air) is blown from
under the bed to burn the fixed carbon.
 Some secondary air (over fire air) is introduced over the coal
bed to burn the volatiles released from the bed.

42. Combustion Of Coal
 Coal may be burnt in a grate by hand firing or by using
mechanical stokers.
1) Hand Firing :-
The grates are usually made of iron bars with 6 to 10 mm gaps
between them. Hand firing can be done either by spreading or
coking method.
In Spreading method, a small quantity of coal is supplied at a
time by spreading it over a part of the fuel bed.in this method, care
is to be taken to maintain uniform bed thickness.

43. Contd.
 While in Coking method, a considerable amount of coal
is fed onto a plate. The heap of fresh coal is slowly
carbonized by heat of the glowing bed.
 The volatile products pass over the bed and get burnt in
the air rising through the grate. Then formation of coke
takes place.
 The coke is then distributed over the bed.

44. Combustion Of Coal
Mechanical Stokers :-
 It functions on the principle of continuous coal feeding. The
evolution of volatile matter is thus uniform and it becomes easier to
control the air required for combustion.
 The mechanical means used are, depending on design,
combinations of the screw feed, the conveyor belt, the bucket
chain, the paddle and the ram.
 There are 3 types, the over-feed, the under-feed and the cross -
feed.

45. Overfeed Stokers

46. Underfeed Stokers

47. Pulverized Coal Firing
 A pulverized coal-fired boiler is an industrial or
utility boiler that generates thermal energy by
burning pulverized coal (also known as powdered coal or coal
dust since it is as fine as face powder in cosmetic makeup) that
is blown into the firebox.
 The basic idea of a firing system using pulverized fuel is to use
the whole volume of the furnace for the combustion of solid
fuels.
 The combustion appliances applied are known as pulverized
fuel (PF) burners.

48. Contd.
 Coal is ground to the size of a fine grain, mixed with air
and burned in the flue gas flow.
 Biomass and other materials can also be added to the
mixture.
 Coal contains mineral matter which is converted to ash
during combustion.
 The ash is removed as bottom ash and fly ash. The
bottom ash is removed at the furnace bottom.

49. Pulverized Burners

50. Contd.

51. Cyclone Firing
 Cyclone furnaces feed coal in a spiral manner into a combustion
chamber for maximum combustion efficiency.
 A cyclone furnace consists of a horizontal cylindrical barrel
attached through the side of a boiler furnace.
 Crushed coal and a small amount of primary air enter from the
front of the cyclone into the burner. In the main cyclone burner,
secondary air is introduced tangentially, causing a circulating gas
flow pattern.
 Coal particles thus have a whirling motion.

52. Contd.
 The products, flue gas and un-combusted fuel, then
leave the burner and pass over the boiler tubes.
 Tertiary air is then released further downstream to
complete combustion of the remaining fuel, greatly
reducing NOx formation.
 A layer of molten slag coats the burner and flows
through traps at the bottom of the burners, reducing the
amount of slag that would otherwise form on the boiler
tubes.

53. Cyclone Combustor

54. Contd.

55. Fluidized Bed Combustion (FBC)
 This is the another method of burning coal.
 These are now commercially available in India in
applications like electricity generation and industrial
boilers where steam is the main product.
 In this ,the coal is crushed and fed to the refractory lined
cylinder to form a bed. Air is supplied through a
perforated distributor plate at the bottom.

56. Contd.
 In this state the coal-air system behaves like a fluid.
 The coal is continuously supplied to the bed and the
turbulence of a fluidized bed causes rapid mixing of
the particles.
 The burning of the coal release heat and the ash may
be removed from the bed by gravity flow .

57. Contd.

58. Thank You