Thermodynamics & Heat Transfer - Steam Boilers Part 2.pdf

Construction & Working of Water & Fire tube Boilers.

1. Mr. V. C. Gadage SIT Polytechnic Ichalkaranji SITCOE,Yadrav-Ichalkaranji. Mr.S.S.Sajane

Thermodynamics & Heat
Transfer

Chapter 2:
Steam Generators and
Steam Turbines

2. Steam boiler
1.Babcock & Wilcox Boiler

3. Content:
1.

•Babcock & Wilcox Boiler

2.
•Construction & working of Babcock & Wilcox Boiler
3.
•Diagram of Babcock & Wilcox Boiler
4.
•Application of Babcock & Wilcox Boiler

4. 1. Babcock & Wilcox Boiler:
Construction :
i.Water tubes
ii.Grate
iii.Furnace
iv.Baffles
v.Super heater
vi.Mud box
vii.Inspection doors

5. Working of Babcock and Wilcox Boiler
Flow of flue gases
Water circulation

6. Working of Babcock and Wilcox Boiler

Feed valve
drum
Down take header
uptake-header
Drum in vapour
Super heater
Steam stop valve
Application
Fire door
CC
Water tube(UTH)
Super heater
Water tube(DTH)
Chimney
ATM
air flow Water flow

7. Steam boiler
2.La-mont boiler:

8. Content:
1.

•La-mont boiler

2.


•Construction & working of La-mont boiler


3.

•Diagram of La-mont boiler

4.

•Application of La -mont boiler

9. 2.La-mont boiler:
i.@ 45000 kg/hr at 500 C & at a pressure of 120 bar.
ii.Vertical axis
iii.High pressure boiler
iv.Multi tube
v.Water tube
vi.Forced circulation

10. Construction :
i.Air Preheater
ii.Centrifugal Pump
iii.Grate
iv.Furnace
v.Water Steam Separator Drum
vi.Water tubes
i.Evaporator
ii.Economiser
iii.Super heater

11. Working of La-mont boiler:
blower
Air preheater
Furnace(cc)
Radiant evaporator
Convective
evaporator
super heater
economiser
Air pre heater
Chimney
atm
Hot well
Economiser
Storage and
separating drum
Circulating pump
Radiant evaporator
Convective
evaporator
Storage and
separating drum
Super heater
Steam stop valve
Gas flow
Water flow

12. Steam boiler
3.Cocharn boiler

13. Content:
1.

•Cocharn boiler

2.


•Construction & working of Cocharn boiler


3.

•Diagram of Cocharn boiler

4.

•Application of Cocharn boiler

14. Cocharn boiler:
i.Fire tube boiler
ii.Vertical axis
iii.Multitubular
iv.cylindrical shell
v.Efficiency around 70%
vi.Low initial cost
vii.Capacity of 20 to 3000kg/hr

15. Construction of Cocharn boiler:

i.Grate
ii.Blow off cock
iii.Fusible plug
iv.Water level indicator
v.Feed check valve
vi.Man hole
vii.Pressure gauge
viii.SSV
ix.Fire tube
x.The furnace & combustion chamber
xi.The hemispherical crown
xii.The smoke box

16. Working of Cocharn boiler:
Water in
Boiler shell
Steam stop valve
application
Fire door
Smoke box
furnace
Fire tubes
Smoke box
chimney
atm
Gas flow
Water flow

17. Steam boiler


4. Loeffler boiler

18. Content:
1.

•Loeffler boiler

2.

•Construction & working of Loeffler boiler

3.


•Diagram of Loeffler boiler


4.

•Application of Loeffler boiler

19. Construction of Loeffler boiler

i.Fan
ii.Air pre heater
iii.Oil fuel or pulverised coal
iv.Super heater
v.Evaporator
vi.Economiser
vii.Feed pump
viii.Drum
ix.Steam circulating pipe

20. 4. Loeffler boiler

i.forced circulation.
ii.Use of superheated steam.
iii.The steam will act as heat carrying and heat
absorbing medium.
iv.The feed water pumps
v.Economizer
vi.From super heater big portion of steam
(about 3/4) is trapped off for external use
and remainder portion (about 1/4) is passed
to evaporator drum.
vii.nozzle

21. Working:

Blower
Air pre heater
CC
Radiant super heater
Convection super
heater
economiser
Air pre heater
Chimney
Atm
Feed pump
economiser
nozzles
Evaporator drum
Steam circulating
pump
Radiant super heater
Convection super heater
Gas flow
Water flow

22. 1. Babcock & Wilcox Boiler:
Construction :
i.Water tubes: Water tubes are placed between the drum and furnace in an inclined
position (at an angle of 10 to 15 degree) to promote water circulation.
ii.These tubes are connected to the uptake-header and the down- comer as shown.
iii.Grate: Coal is fed to the grate through the fire door.
iv.Furnace: Furnace is kept below the uptake-header.
v.Baffles: The fire-brick baffles, two in number, are provided to deflect the hot flue
gases.
vi.Super heater: The boiler is fitted with a superheater tube which is placed just under
the drum and above the water tubes
vii.Mud box: Mud box is provided at the bottom end of the down comer.
viii.Inspection doors: Inspection doors are provided for cleaning and inspection of the
boiler

23. i.Working of Babcock and Wilcox Boiler:
ii.Coal is fed to the grate through the fire door and is burnt.
iii.A) Flow of flue gases:
iv.The hot flue gases rise upward and pass across the left-side portion of the water tubes.
v.The baffles deflect the flue gases and hence the flue gases travel in the zig-zag manner (i.e., the hot gases are deflected by
the baffles to move in the upward direction, then downward and again in the upward direction) over the water tubes and
along the superheater .
vi.The flue gases finally escape to atmosphere through chimney.
vii.
B) Water circulation:
viii.That portion of water tubes which is just above the furnace is heated comparatively at a higher temperature than the rest of
it.
ix.Water, its density being decreased, rises into the drum through the uptake-header. Here the steam and water are separated
in the drum.
x. Steam being lighter is collected in the upper part of the drum.
xi. The water from the drum comes down through the down –comer into the water tubes.
xii.A continuous circulation of water from the drum to the water tubes and water tubes to the drum is thus maintained.
xiii.The circulation of water is maintained by convective currents and is known as “natural circulation”.
xiv.A damper is fitted as shown to regulate the flue gas outlet and hence the draught.

24. 2.La-mont boiler:

i.It is modern high pressure water tube boiler working on a forced circulation.
ii.Capacity of steam generation is @ 45000 kg/hr at 500oC & at a pressure of
120 bar.
iii.Circulation is done by centrifugal pump.
iv.The forced circulation causes the feed water to circulate through the water
walls & drums equal to ten times the mass of steam evaporated, to prevent the
tubes being overheated.
v.The feed water passes through the economiser to an evaporating drum. It is
then drawn to the circulating pump through the tubes.
vi. The pump delivers the feed to the header.
vii. The header distributes water through nozzles into the generating tubes acting
in parallel. The water & steam from these tubes passes into the drum.
viii. The seam in the drum is then drawn through the superheater.
ix.Advantage – It is flexible, compact & small size of drum.

25. 3. Cochran Boiler:
i.Cochran boiler is a vertical, multi tube boiler, commonly used for small capacity
steam generation. Figure shows the arrangement of boiler.
ii.It consists of a cylindrical shell with the crown having hemispherical shape.
iii.The grate is placed at the bottom of the furnace and ash pit is below the grate.
iv. The furnace and the combustion chamber are connected through a pipe.
v. The hot gases from the combustion chamber flow through the nest of horizontal fire
tubes.
vi. The hemispherical crown of the boiler shell gives maximum strength. Coal or oil
can be used as fuel.
vii. The smoke box is provided with doors for cleaning of the interior of the fire tubes.
viii.This boiler is very compact and requires minimum floor area.
ix.It gives 70% thermal efficiency.

26. 4. Loeffler boiler

i.
Working:
ii.The economizer extracts sensible heat from flue
gases and hot water at temp. close to saturation
temp. is passed to evaporator drum.
iii.From super heater big portion of steam (about 3/4)
is trapped off for external use and remainder portion
(about 1/4) is passed to evaporator drum.
iv.The evaporator drum which is used provided with
set of nozzle through which steamenters in
evaporator drum.
v.The steam from evaporator drum is passed to
superheater through circulatingpump.
vi.The air preheater maybe placed in path of flue gases
to supply the hot air incombustion chamber.
vii.Loeffler boiler has steam-generating capacity of 100
tons/hour at 140 bar pressure.