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3.9.1
Procedure to refer burner operating condition
at an altitude and/or at a combustion supporter
air temperature different to the standard values
(328 ft above sea level, 68 °F).
Altitude
Altitude
bar. press.
ft a.s.l.
m a.s.l.
"w.c.
0
0
399
328
100
394
1.000
305
385
2.000
610
371
3.000
915
358
4.000
1.220
345
5.000
1.525
332
6.000
1.830
320
7.000
2.135
307
8.000
2.440
294
F - correction factor of discharge head and delivery in relation to temperature and altitude.
Reference conditions:
–
Air temperature 68 °F (20 °C)
–
Barometric pressure 394 ''w.c. (1000 mbar)
–
Altitude 328 ft a.s.l. (100 m a.s.l.)
3.10 Minimum furnace dimensions
The firing rates were obtained in special test boilers.
Fig. 5 indicates the diameter and length of the test combustion
chamber.
Technical description of the burner
bar. press.
0
5
mbar
32
41
1013,00
1,087
1,068
1000,00
1,073
1,054
977,40
1,049
1,030
942,80
1,012
0,994
908,20
0,975
0,957
875,80
0,940
0,923
843,50
0,905
0,889
811,85
0,871
0,856
779,80
0,837
0,822
747,80
0,803
0,788
11
AIR TEMPERATURE
10
15
20
50
59
68
1,049
1,031
1,013
1,035
1,017
1,000
1,012
0,994
0,977
0,976
0,959
0,943
0,940
0,924
0,908
0,907
0,891
0,876
0,873
0,858
0,844
0,841
0,826
0,812
0,807
0,793
0,780
0,774
0,761
0,748
Example
Using the Tab. C, for an altitude of 3,000 ft and an air temperature
of 68 °F, an F factor value is obtained equal to 0.908;
if the capacity at the boiler furnace is Qfoc = 4,500 Mbtu/h, the cor-
rect output will be equal to:
Qburner = Qfoc / F = 4,500 / 0.908 = 4,956 Mbtu/h
Example
Output 6400 Mbtu/hr - diameter 31.5 inch - length 10.4 ft.
GB
25
30
40
77
86
104
0,996
0,980
0,948
0,983
0,967
0,936
0,961
0,945
0,915
0,927
0,912
0,883
0,893
0,878
0,850
0,861
0,847
0,820
0,829
0,816
0,790
0,798
0,785
0,760
0,767
0,754
0,730
0,735
0,723
0,700
Tab. C
D9086
Fig. 5
20094575
°C
°F
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