Technical description of the burner
9
20044771
GB
3.8
Firing rate
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 diagram.
3.8.1
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 temper-
ature = 68°F, 20°C)
To get the combined correction in case of different air temper-
ature, 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
D9093
Pr
essur
e in combustion
chamber
-
mb
a
r
Firing rate for C-ETL Canadian Listing
A
