Bentone bg 300, Installation And Maintenance Instruction

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19
Bentone
5.4
Calculation of gas flow
Formula symbol Description Example values
V
N
Standard gas volume [Nm3/h]
Gas volume at normal condition 15 °C 1013 mbar
-
Q
Boiler output [kW] 140 kW
H
i
Lower calorific value of gas [kWh/m
3
]
Natural gas under normal conditions 15 °C 1013 mbar, EN 676
9.45 kWh/m
3
η
Boiler efficiency (e. g. 90%) 0.9
f
Conversion factor (pressure and temperature compensation)
-
t
Gas
Gas temperature at gas meter [°C] 15 °C
P
Baro
Barometric air pressure [mbar] 945 mbar
P
Gas
Pressure of gas at the gas meter [mbar]
20 mbar
V
Operating volume [m
3
/h]
-
VG Gas flow measured at the gas meter [m
3
] 0.46 m
3
T
Measuring time for consumed gas quantity [s] 91 s
V
N
=
Q
V
N
=
140 kW
=
16.5 m
3
/h
η
· H
i
0.9 · 9.45 kW/m
3
Calculate standard volume using the following formula:
f
=
273
x
P
Baro
+ P
Gas
f
=
273
·
945 + 20
= 0.90
273 + t
Gas
1013 273 + 15 1013
Calculate conversion factor using the following formula:
V
=
V
N
V
=
16.5 m
3
/h
=
18.2 m
3
/h
f
0.90
Calculate gas volume using the following formula:
V
=
3600 · V
G
V
=
3600 · 0.46 m
3
=
18.2 m
3
/h
T
91 sek
Determine operating volume with the following formula:
Gas quality kWh/Nm 3 MJ/Nm 3
Natural gas G20
9.5 34.02
Natural gas G25 8.2
29.25
Calorific value of the gas
Lower calorific value H
i
at normal conditions 15 °C and 1013 mbar, EN 676.
For exact calorific value of the gas, contact the gas distributor.
172 515 13-2
Height above
sea level [m]
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
P
Baro
[mbar] 1013
1001
989 977 966 954 943 932 921 910 899
888 877
Gas quality
kWh/Nm 3 MJ/Nm 3
Butane
G30 32.25 116.09
Propane
G31
24.44 88.00