Ø Boiler is an apparatus to
produce steam.
Ø Thermal energy released
by
combustion of
fuel issued to
make steam at
the desired
temperature and pressure.
The steam produced is
used
for:
1). For generating power in steam engines or
steam turbines.
2). Heating the residential
and industrial
buildings.
3). Performing certain processes
in the sugar mills,
chemical and textile
industries.
Selection of boiler:
} The working pressure &
quality of steam.
} Steam generation.
} Floor area available.
} Accessibility for repair & inspection.
} Comparative initial
cost.
} Erection facilities.
} The probable load factor.
} The fuel & water available.
} Operating &
maintenance cost.
BOILER PROPERTIES
a). Safety:
The boiler should be safe under the operating conditions.
b). Accessibility: the various part of boiler should be accessible for
repair &
maintenance.
c). Capacity: Should be capable of supplying Steam according to the requirements.
d). Efficiency: Should be able to absorb a maximum amount of heat
produced
due to burning of fuel in the furnace.
e). It should be simple in construction.
f). Its initial cost and maintenance cost is
low.
g). It should be capable of quick
starting and loading.
The boiler may be classified
as :
1. Horizontal, vertical or inclined
2. Fire tube &
water tube
3. Externally fired &
internally fired
4. Forced circulation &
internally fired
5. High pressure & low pressure
6. Forced circulation &
natural circulation
7. Stationary & portable
8. Single tube &
multi tube boilers
ØBoiler mainly classified as:
A. fire tube
b. water tube
a). FIRE TUBE BOILERS
b). WATER TUBE BOILERS
ØComparison between Fire-tube &
water-tube boilers
|
S no.
|
Particulars
|
Fire tube
boilers Water tube boilers
|
|
|
1.
|
Mode of firing
|
Internally fired Externally fired
|
|
|
2.
|
Rate of steam production
|
lower Higher
|
|
|
3.
|
construction
|
Difficult Simple
|
|
|
4.
|
transportation
|
Difficult Simple
|
|
|
|
|
|
|
|
5.
|
Treatment of water
|
Not so necessary
|
More necessary
|
|
6.
|
Operating pressure
|
Limited
to 16 bar
|
Under high pressure as
100 bar
|
|
7.
|
Floor area
|
More floor
area
|
Less floor area
|
|
8.
|
Shell diameter
|
Large for same power
|
Small same power
|
|
9.
|
explosion
|
Less
|
More
|
|
10.
|
Risk of bursting
|
lesser
|
More risk
|
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