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Boilers
How
Boiler Works
Engineeringinsider
A boiler can be
defined as a closed vessel in which steam is produced from water by combustion
of fuel.
A boiler is used in
many industries such as in steam power generation, in sugar industries, in
textile industries for sizing and bleaching etc. and in many other chemical
industries.
Earlier it was mainly
used in generating power in the steam engine.
A boiler is simply an
enclosed vessel which boils water and ultimately turns it into steam which is
used for heating of rooms and heavy fuel oils on the ships.
The boilers are fitted
with different safeties as the steam pressure is up to 8 bars in most cases.
There are normally two
kinds of boilers on ships, Auxiliary and Exhaust. Some ships have composite
boilers.
Boiler are of two type
1.
STB
(Smoke tube Boiler) or donkey boiler
2.
WTB
(Water tube Boiler) or high pressure boiler
On board a vessel, STB or
WTB maybe used as per the requirement.
Stages
Of Combustion-
Since a boiler operates
through fuel combustion, heat transfer and energy release, the stages of
combustion are typically described as follows:
1.
Standby:
boiler is ready to meet demand.
2.
Call
For Heat: system pressure or temperature has fallen below a pre-determined set
point.
3.
Safety
Check: A series of self-tests are performed to ensure the boiler is safe to
operate (water level, gas pressure, electrical status, etc.).
4.
Pre-purge:
a forced draft fan or blower is used to force air through the furnace or
combustion chambers to remove any potential unburned fuel that might be
present.
5.
Pilot
Ignition: fuel and air are mixed and forced through a small pilot flame tube
where a spark is generated to ignite the fuel.
6.
Pilot
Flame Trial: a flame sensor is used to make sure a strong, sustainable flame
has been developed.
7.
Main
Ignition: Fuel and air are mixed and forced through a burner nozzle and are
ignited by the pilot flame. Main combustion continues at various rates – low to
high fire – until the system set point pressure or temperature is met.
8.
Post
Purge – the forced draft fan or blower is run to remove any potential unburned
fuel from the furnace or combustion chamber.
9.
Boiler
goes into standby mode until temperature or pressure falls below the set point.
WORKING
PRINCIPLE OF BOILER-
The basic working principle of boiler is very simple and
easy to understand.
The boiler is essentially
a closed vessel inside which water is stored. Fuel (generally coal) is bunt in
a furnace and hot gasses are produced.
These hot gasses come in
contact with water vessel where the heat of these hot gases transfer to the
water and consequently steam is produced in the boiler.
Then this steam is piped
to the turbine of thermal power plant.
There are many different
types of boiler utilized for different purposes like running a production unit,
sanitizing some area, sterilizing equipment, to warm up the surroundings etc.
Nice blog! Thanks for sharing such an informative blog.
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