Appendix - Burner Firing Rates According To Air Density - Riello RS 28/M Installation, Use And Maintenance Instructions

APPENDIX
- Burner firing rates according to air density
average barom.
above sea level
ft m " W.C.
0 0
329 100
658 200
300
987
1316 400
1645 500
1974 600
2303 700
2632 800
2961 900
3290 1000
3947 1200
4605 1400
5263 1600
5921 1800
6579 2000
(A)
The FIRING RATE area values have been obtained considering a surround-
ing temperature of 68°F (20°C), and an atmospheric pressure of 398" W.C.
and with the combustion head adjusted as shown on page 8.
The burner may be required to operate with combustion air at a higher tem-
perature and/or at higher altitudes.
Heating of air and increase in altitude produce the same effect: the expan-
sion of the air volume, i.e. the reduction of air density.
The burner fan's delivery remains substantially the same, but the oxygen
content per cubic meter and the fan's head are reduced.
It is therefore important to know if the maximum output required of the burner
at a given combustion chamber pressure remains within the burner's firing rate range even at different temperature and altitude con-
ditions. Proceed as follows to check the above:
1 -Find the correction factor F in the Table (A) for the plant's air temperature and altitude.
2 -Divide the burner's delivery Q by F in order to obtain the equivalent delivery Qe:
Qe = Q : F (MBtu/hr)
3 -In the firing rate range of the burner, Fig. (B), indicate the work point defined by:
Qe = equivalent delivery
H1 = combustion chamber pressure
The resulting point A must remain within the firing rate range.
4 -Plot a vertical line from Point A as shown in Figure (B) and find the maximum pressure H2 of the firing rate.
5 -Multiply H2 by F to obtain the maximum reduced pressure H3 of the firing rate.
H = H x F (" W.C.)
3 2
If H3 is greater than H1, as shown in Fig. (B), the burner delivers the output required.
If H3 is lower than H1, the burner's delivery must be reduced. A reduction in delivery is accompanied by a reduction of the pressure in
the combustion chamber:
Qr = reduced delivery
H1r = reduced pressure
Qr 2
( )
H r = H x
1 1
Q
Example, a 5% delivery reduction:
Qr = Q x 0.95
2
H1r = H1 x (0.95)
Steps 2 - 5 must now be repeated using the new Qr and H1r values.
Important: the combustion head must be adjusted in respect to the equivalent delivery Qe.
pressure
mbar
0 (0°C)
399 1013 1,087
394 1000 1,073
389 989 1,061
385 978 1,050
380 966 1,037
376 955 1,025
372 944 1,013
367 932 1,000
363 921 0,988
358 910 0,977
354 898 0,964
346 878 0,942
337 856 0,919
329 836 0,897
321 815 0,875
313 794 0,852
CORRECTION FACTOR
Air temperature
41 (5°C) 50 (10°C) 59 (15°C)
1,068 1,049 1,031
1,054 1,035 1,017
1,042 1,024 1,006
1,031 1,013 0,995
1,018 1,000 0,983
1,007 0,989 0,972
0,995 0,977 0,960
0,982 0,965 0,948
0,971 0,954 0,937
0,959 0,942 0,926
0,930 0,914
0,946
0,925 0,909 0,893
0,902 0,886 0,871
0,881 0,866 0,851
0,859 0,844 0,829
0,837 0,822 0,808
" W.C.
H
H
H
18
F
°F (°C)
68 (20°C) 77 (25°C)
1,013 0,996
1,000 0,983
0,972
0,989
0,978 0,962
0,966 0,950
0,955 0,939
0,944 0,928
0,932 0,916
0,921 0,906
0,910 0,895
0,898 0,883
0,878 0,863
0,856 0,842
0,836 0,822
0,815 0,801
0,794 0,781
2
3
A
1
D2617
Qe
86 (30°C) 104 (40°F)
0,980 0,948
0,967 0,936
0,956 0,926
0,946 0,916
0,934 0,904
0,923 0,894
0,913 0,884
0,901 0,872
0,891 0,862
0,880 0,852
0,868 0,841
0,849 0,822
0,828 0,801
0,808 0,783
0,788 0,763
0,768 0,743
MBTU/h
(B)