What is the principle operation of a boiler?

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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