MIL-HDBK-1003/6
S.G =
Specific gravity of feedwater.
5.1 =
42.42 Btu/Min./HP hour
8.33 Lbs./gal.
(d) Pump Horsepower Input:
(16)
EQUATION:
Input HP =
Q x TDH x S.G.
3960 x Ep x Ed
where:
Q
=
Gallons per minute.
TDH
=
Total dynamic head, feet.
S.G. =
Specific gravity to 60 degrees F water.
Ep
=
Pump efficiency at specific point of operation.
Ed
=
Efficiency of motor or driver at same point of operation.
3960 =
33000 ft. pounds per H.P. minute
8.33 lbs. per gallon
8.3
Fans
8.3.1
Types. The major boiler fans are the forced draft and induced
draft fans which supply air for combustion of fuel and transport flue gases
through the boiler. Additional fans provide pneumatic injection of fuel,
recirculation of unburned carbon, gas recirculation, and forced overfire air.
Numerous small fans are used for cooling and sealing of igniters, scanners and
other equipment.
Pressurized Boilers. Boilers are either pressurized or have
8.3.2
balanced draft for combustion. A pressurized boiler operates at above
atmospheric pressure in the furnace. The forced draft fan supplies the air
necessary for proper combustion in the furnace and will also provide a
sufficient volume of air to compensate for leakage losses and sealing air
requirements.
Balanced Draft Boilers. Balanced draft boilers are systems where
8.3.3
forced draft fans supply air to the furnace and induced draft fans exhaust the
products of combustion. The furnace is kept at a slightly negative pressure,
0.2 to 0.5 inches W.C., by the induced draft fan which is generally located
downstream of the particulate removal system.
Forced Draft Fans. Forced draft (FD) fans operate with reasonably
8.3.4
clean, cool or warm air. Forced draft fans should be designed for quietness,
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