Answer / prof. diwan

what karthik has written for air preheater is right but the
air blower is used to blow the air from outside the boiler
to increase the rate of combustion

Answer / karthick

air pre heater is used to heat the air required for
combustion of fuel in the boiler.it utilizes the heat of
flue gases and is mounted in the path of chimney

air blower is used to create the necessary draught inside
the boiler if natural draught is not sufficient to produce
the required pressure difference

Answer / arul - mz

Like to add one more thing...

Usuallly In APH there will be 3 sectorial compartments (in
a cylinder well separated from each other) and covered by
two discs (one top & another bottom) The sectors will carry
the following
1) bigger part (included angle = 180 deg app) takes the
flue gas.
2) two Smaller parts- carrying PRIMARY AIR (70-80 deg), &
SECONDARY AIR (100-110 deg)....

Primary air to remove moisture from the coal by pre heating
the coal.

Secondary air to supply hot air to the combustion chamber.

This is as per the BHEL-design implementation for all the
sites.

Using the APH, We are Saving hardly 5-8 crores p.a worth
energy for running a 80 MW powerplant...
:-)

Answer / ranveer upadhyay

Air preheater is used to recover heat from the exhaust flue
gases. It is installed between economiser and the chimney.
the air is required for the purpose of combustion is drawn
through the air preheater where its temperature is raised.
where as air blower is used for:
to create the necessary draught inside
the boiler if natural draught is not sufficient to produce
the required pressure difference

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