Eclipse Combustion AIRHEAT AH-MA - Manual (Page 10)

Eclipse AH-MA Air Heat Burner v2, Design Guide 160, 8/1/05 10
Calculating the maximum input requirements
To calculate the total burner maximum input required, solve:
Max. Input (Btu/hr) = 1.3 x SCFM x
∆ T (max)
Caution:
This is an approximation based on the gross heating value of the
fuel. For more accurate heat balance calculations, refer to the
Eclipse Combustion Engineering Guide (EFE-825).
Choosing design heat input at high fire
See Data Sheet No. 160 for the following:
1) Use the “Operating Range” chart to determine the maximum and
minimum heat inputs per foot of burner based on the known air
pressure drop.
2) Use the “Flame Length” chart to check flame length versus available
distance downstream of the burner for uniform temperature
distribution.
Determining the length of burner needed
Burner length, feet = max. heat input, total burner (Btu/hr)
heat input per foot (Btu/hr/ft)
Note:
Round fractional lengths (in ft.) up to the next half-foot.
Calculating minimum input required
1) Minimum Input (Btu/hr) = 1.3 x SCFM x T (min)
2) Min. Heat Input per foot, Btu/hr/ft = min. heat input, total burner, Btu/hr.
burner length, feet
3) With the minimum heat input per foot, go to the “Operating
Range” chart in Data Sheet No. 160 and confirm that the burner
can operate at the input for the air pressure drop the burner will
see. If the minimum input required is too low, there are two
options to obtain this operating condition:
a. Use a staged burner control (see burner staging and control
methods in this section).
b. Modulate the air flow to a lower pressure drop, thus lowering
the minimum input capability of the burner.
Example: A make-up air heat burner will be used to heat
60,000 SCFM air from 0°F to 80°F maximum; and, from 75°F to
80°F minimum. Air ∆ P across the burner is designed to be
0.7"w.c. at high fire. The fuel is natural gas.
1) Max. Input Required: Btu/hr = 1.3 X 60,000 X 80 = 6,240,000
Btu/hr.
Step 1: Burner design
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