Boiler operation
Boiler
working procedure:
The boiler is supplied with water by a feed pump.
Water enters the boiler through a feed check valve.
When the water reaches normal water level which is approximately the middle of
the water gauge glasses, the feed pump is stopped by the dual control.
The burner is bolted to the hinged front door. Air
required for combustion is provided by a forced draught fan which is integral
with the burner unit.
The furnace receives heat radiant from the flame and
the hot gases from the flame give up heat to tubes in the second pass as they
travel to the front chamber. Gases turn into front chamber and give up more
heat to the tubes in the third pass as they travel to the rear chamber. The
gases leave the boiler by the chimney at the top of the rear chamber.
As the steam pressure rises the pressure has been
shown in pressure gauge. When the pressure is sufficiently high the main stop
valve can be opened to allow steam to pass to the process or heating system.
When the steam leaves the boiler the water level
will drop until it reaches a point which is equally 12.5 mm = ½ inches below
the normal level. The dual control will start the feed pump and more water will
be fed into the boiler.
Two pressure switches are fitted to the boiler one
acts as a pressure limit control and other is pressure control. The pressure
control will be a high or low pressure stat in the case of high or low burners
and a modulating pressure control in the case of modulating burners, which
controls the firing rate of the burners. Which control controls the firing rate
of the burner.
When the boiler pressure reaches the maximum
required the limit pressure state shut down the boiler. The burner will restart
automatically when the pressure falls to a preset poijnt bellow the maximum.
One should limit the pressure state fail to stop the
burner, the safety valve will lift the excess pressure will escape to
atmosphere, thus preventing any further rise in boiler pressure.
One must follow this caution
One must be checked the setting of the safety valve
prior to dispatched as manufacturer recommendation.
If necessary the valve should be adjusted during
commissioning. The set pressure should not be altered except by a suitably
qualified person, who is also able to fully assess the consequences of carrying
out such an alternation.
The safety valve is provided with easing gear for
test purposes and supplied with a padlock to prevent unauthorized interference.
The key should be retained in a secure place under the supervision of a
qualified person.
A steam accumulation test at the maximum evaporative
capacity with the stop valve closed
should be performed in the presence of the inspecting authority before the
boiler is put into normal operation.
If for any reason water is not supplied to the
boiler and the water level falls to a point
about 50 mm = 2 inches below the normal level the dual fuel control stop
the burner and activate the low water alarm. Provided the water level is
restored before reaching the extra lowest water level the alarm will stop and
the burner will restart automatically.
If one has been seen continuously water level fall
to reaches 75 mm or 3 inches below the normal level , the over riding control
will activate the extra lowest water alarm rending the burner in a lockout
condition.
If one has been shown let water out of the boiler,
this can be done by opening the blow down valve at the rear of the boiler.
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