Technical description of the burner
9
20052068
GB
The maximum output is chosen within area A of the diagram
(Fig. 4).
The minimum output must not be lower than the minimum limit of
the diagrams.
3.7.1
Procedure to refer burner operating condition
in high altitude plants
Find the CORRECTED BURNER CAPACITY for the plant’s alti-
tude in chart 1 and the CORRECTED PRESSURE in chart 2.
Check in the firing rate graph of the burner (Fig. 4), if the working
point defined by the values above is within the range limits.
If not, higher burner size is needed.
Note
➤
Charts are based only on altitude variation (reference tem-
perature = 68°F, 20°C)
➤
To get the combined correction in case of different air tem-
perature, a compensation of 1000 ft each 20°F (305 m each
11°C) is applicable (100 ft = 2°F).
Example
Rated capacity
= 3000 MBtu/hr - Rated air pressure = 1.5” WC
Real altitude
= 5000 ft - Real temperature = 108°F
∆
= 108°F - 68°F (reference temp.) = 40°F
(equivalent 2000 ft variation)
40 : 2 = 20 x 100 = 2000 ft
Proceeding as descripted above and considering a “virtual altitude”
of (5000 + 2000) ft:
–
3000 MBtu/hr at 7000 ft, the corrected capacity is 3847 MBtu/hr
–
1.5” WC at 7000 ft, the corrected burner air pressure is 1.92
Reference conditions:
–
Ambient temperature 68 °F (20 °C)
–
Barometric pressure 394” WC (1000 mbar)
–
Altitude 328 ft a.s.l. (100 m a.s.l.).
WARNING
The firing rate was obtained considering a room
temperature of 68 °F and an atmospheric pressure
of 394 “WC (approx. 0 ft above sea level), with the
combustion head adjusted.
Fig. 4
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D2431
A
