HASMUKH GOSWAMI COLLEGE OF ENGINEERING,VAHELAL,AHMEDABAD
ELEMENTS OF MECHANICAL ENGINEERING(2110006)
PRACTICAL:-01
ENR NO:-
DATE:-
AIM: TO STUDY ABOUT DIFFERENT TYPES OF BOILER, BOILER MOUNTINGS &
ACCESSORIES.
INTRODUCTION OF BOILER:
According to Indian Boiler Regulation “Boiler” is closed pressure vessel in which steam is
generated with capacity exceeding 25ltrs, gauge pressure greater than or equal to 1Kg/cm3 &
water is heated at 100oC or above.
“Boiler” is closed pressure vessel in which steam is generated from water at required pressure
and temperature.
CLASSIFICATION OF BOILER
According to geometric orientation (axis) of the boiler: Horizontal boiler:-If the axis of the boiler is horizontal, then it is called…….
 Vertical boiler:-If the axis of the boiler is vertical, then it is called…….
 Inclined boiler:-If the axis of the boiler is inclined, then it is called…….
According to position of water and hot gases: Fire tube boiler (Figure-1): - If the hot gases pass through the tubes and water is
surrounding the tubes, then the boiler is called ……….
 Water tube boiler (Figure-2): - If the water passes through the tubes and hot gases
surrounding the tubes, then the boiler is called ……….
According to location of the furnace: Externally fired boilers: - In this boiler the furnace is placed outside of the boiler shell.
 Internally fired boilers: - In this boiler the furnace is placed inside of the boiler shell.
According to working pressure: High pressure boiler:-If the pressure of boiler is higher than 25 bar then it is called….
 Medium pressure boiler: - If the pressure of boiler is between 10 to 25 bar then it is
called….
 Low pressure boiler: - If the pressure of boiler is between 3.5 to 10 bar then it is
called….
According to numbers of tubes in the boiler: Single tube boiler: - If there is one single tube inside the boiler for water or gas
circulation then it is called………..
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
Multi tube boiler: - If there are more than one tube inside the boiler for water or gas
circulation then it is called………..
According to mobility of boiler: Stationary boiler: - If the boiler is fixed at one place & cannot move easily from one
place to other then it is called………
 Mobile boiler:-If the boiler is move from one place to other easily then it is called……..
According to method of water circulation: Natural circulation boiler (Figure-3):- In this boiler, water flow takes place naturally,
by density difference of water. The flow of water and steam are set up due to density
difference resulting from difference in temperature. The low capacity boilers use natural
circulation.
 Forced circulation of boiler (Figure-4):-In this boiler water flow takes place by a pump.
The high capacity boilers use natural circulation.
Cochran boiler (Figure-5):
Characteristics: It is vertical boiler. It is horizontal tube boiler.
 It is multi tube boiler. It is portable boiler.
 It is fire tube boiler.
 It is internally fired.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The water is supplied to the boiler through the feed check valve.
 The coal is supplied to the grate through the fire door.
 The hot gases are produced from the complete combustion of fuel (coal).
 This hot gases are enters inside the fire tubes from the combustion chamber because
of the fire brick lining.
 The heat transfer takes place between water and tubes (hot gases), and water is
converted in to the steam.
 This steam is collected at the top of the boiler.
 The ash formed is collected in ash pit and hot gases are discharged in atmosphere
through the chimney.
Lancashire boiler (Figure-6):
Characteristics: It is a horizontal and stationary boiler.
 It is fire tube & multi tube boiler.
 It is internally fired boiler.
 It is medium pressure boiler.
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
List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The coal is supplied to the grate through the fire door.
 The water is supplied to the boiler through the feed check valve.
 Path of flue (hot) gases:Grate (coal) fire tube bottom flue pipe side flue pipe chimney atmosphere
 Due to this hot gas path the water in shell is heated two times once by bottom pipe &
again by side pipe. Because of the heat transfer water is converted in to the steam and
collected at the top of the boiler shell.
 Damper regulates mass flow rate of hot gases.
Locomotive boiler (Figure-7):
Characteristics: It is a horizontal boiler.
 It is fire tube & multi tube boiler.
 It is portable boiler.
 It is internally fired boiler.
 It is medium pressure boiler.
 Force circulation of water.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The coal is feed in to the fire-box through the fire hole.
 The hot gases which are generated due to the burning of the coal are deflected by fire
brick arch.
 Path of flue (hot) gases:Grate (coal)  fire box  fire tubes  smoke box  chimney  atmosphere
 The water is feed in to the barrel from feed check valve.

The heat of hot gases is transfer to the water through the hot tube surfaces.
 The steam generated is collected in a dome shape chamber above the water surface.
 The wet steam is goes in to the super heater from steam regulator.
 The super heated steam is fed to the steam engine or steam turbine.
Babcock & Wilcox boiler (Figure-8):
Characteristics: It is water tube & multi tube and stationary boiler.
 It is externally fired boiler.
 Natural circulation of water.
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 It is high pressure boiler.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The water is feed in to the drum through feed check valve.
 Due to the gravitational force water feed in to the inclined tube.
 The coal is feed to the grate by help of stroker. The coal is fired; hot gases produced
& moves surrounding to the tubes.
 The baffle gives the direction to the hot gases. So the contact between tube surface &
hot gases increased. It results in increasing heat transfer rate, so the steam production
rate is increase.
 The wet steam enter in to the anti priming pipe & then super heater tubes.
 From the super heater, super heated steam moves to the prime mover.
HIGH PRESSURE BOILERS:La-Mont boiler (Figure-9):
Characteristics: High pressure boiler.
 Water tube boiler.
 Forced circulation of water.
 It is stationary boiler.
 It is internally fired boiler.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: Flue(Hot) gases path:Combustion chamber  convective evaporator  super heater  economiser  air
preheater  chimney  atmosphere
 Water/Steam path:Hot well feed water pump economizer steam drum steam circulating
pump radiant evaporator convective evaporator steam drum super heater
prime mover
 The feed water from hot well is pumped to boiler drum through economiser.
 In economiser, the feed water absorbs the sensible heat from flue gases.
 The feed water in radiant evaporator absorbs the radiant heat and in convective
evaporator absorbs the convective heat and evaporates.
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 The steam collected in upper part of separating steam drum. Then it passes through
super heater where it becomes super heated.
 The super heated steam supplies to the prime mover.
Benson boiler (Figure 10):
Characteristics: High pressure boiler.
 Water tube boiler.
 Forced circulation of water.
 It is stationary boiler.
 It is internally fired boiler.
 It is once through boiler.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The incoming water completely evaporated and super heated in single pass, so it is
called once through boiler.
 The feed water is supplied by feed pump at high pressure.
 This water passes through economiser and then radiant evaporator where most of
water is evaporated.
 The remaining water is evaporated in convective evaporator and converted in to the
steam.
 The steam is passed through the super heater and finally supplied to the prime mover.
Lo-effler boiler (Figure 11):Characteristics: High pressure boiler.
 Water tube boiler.
 Forced circulation of water.
 It is stationary boiler.

List of mountings: Pressure gauge, Steam stop valve, Safety valve, Feed check valve, Water level
indicator, Blow off cock, Man hole, Fusible plug

Working of the boiler: The high pressure feed pump draws water through the economiser and deliver it in to
the evaporating drum.
 An evaporator drum is outside of the boiler.
 Feed water is evaporated by mixing super heated steam coming from super heater.
 The steam circulating pump draws saturated steam from evaporator drum.
 Then steam passes through radiant and convective super heaters where it is heated to
required temperature.
 About 1/3 of super heated steam is supplied to prime mover and remaining 2/3 super
heated steam is supplied to evaporator drum to evaporate the feed water.
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Velox boiler (Figure 12):Working of the boiler: The air is compressed by air compressor before supplying to the combustion chamber.
 The fuel and air are injected downwards in to a vertical combustion chamber.
 There are water tubes inside the combustion chamber.
 The hot gases deflected up wards with supersonic velocity. The heat transfer from hot
gases to water at very high rate.
 The water evaporates in side of the tubes, and then mixture passes in to a separator.
 Then the steam passes to super heater and then prime mover.
 Then the remaining water again passed in the water tubes with new feed water coming
from economiser.
 The hot gases after heating the water and steam flow through the gas turbine and
economiser.
 The hot gases rotate the gas turbine-air compressor & also increase the temperature of
feed water in economiser.
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