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PART II: INSTALLATION
Sizing of the FGR pipe (FGR burners only)
ATTENTION! Performance curve is obtained in a plant designed according to the following guidelines, size the
FGR pipe as per the example below.
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1
2
Keys
1 Stainless steel FGR pipe, insulated
2 Burner
3 Boiler
The temperature probe for flue gas temperature compensation must be installed on the chimney.
The internal diameter of the FGR conduit must be dimensioned considering a maximum speed of 10 m / s. Assume a volumetric flow
rate of recirculatig fluegases for the dimensioning equal to 20% of the comburent air flow.
ATTENTION! Pipe elbows increase pressure losses, so limit their use as much as possible.
Example:
Let's say 4.816 kW is the maximum burner output:
required combustion air flow will then be 5.800 Stm
Flue gas temperature:
Ambient temperature:
FGR flow for dimensioning:
FGR flow corrected for flue gas temperature:
FGR pipe section:
So in this example, pipe internal diameter must be larger than 245 mm to ensure proper FGR flow.
* FGR = Flue gas recirculation system
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6
7
4
3
5
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4 Bellow unit (a counter-flange supplied
loose is to be welded to the FGR duct)
5 FGR butterfly valve
6 Siphon and condensate drainage
/h = 1,61 Stm
/s in standard conditions (15 °C; 1.013 mbar).
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3
150 °C or 150 + 273,15 = 423,15 K
15 °C or 15 + 273,15 = 288,15 K
1,61 x 20% = 0,322 Stm3 / s
0,322 x 423,15 / 288,15 = 0,473 m3 / s @ (t = 150 °C)
0,473 m3/s / 10 m/s = 0,0473 m2
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8
7 Stack
8 PT1000 Flue gas temperature probe
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6
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6
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