PART II: INSTALLATION
18
Sizing of the FGR pipe (FGR burners only)
1111
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.
Example:
Let’s say 4.816 kW is the maximum burner output:
required combustion air flow will then be 5.800 Stm
3
/h = 1,61 Stm
3
/s in standard conditions (15 °C; 1.013 mbar).
* FGR = Flue gas recirculation system
ATTENTION! Performance curve is obtained in a plant designed according to the following guidelines, size the
FGR pipe as per the example below.
ATTENTION! Pipe elbows increase pressure losses, so limit their use as much as possible.
Flue gas temperature:
150 °C or 150 + 273,15 = 423,15 K
Ambient temperature:
15 °C or 15 + 273,15 = 288,15 K
FGR flow for dimensioning:
1,61 x 20% = 0,322 Stm3 / s
FGR flow corrected for flue gas temperature:
0,322 x 423,15 / 288,15 = 0,473 m3 / s @ (t = 150 °C)
FGR pipe section:
0,473 m3/s / 10 m/s = 0,0473 m2
So in this example, pipe internal diameter must be larger than 245 mm to ensure proper FGR flow.
8
7
6
1
2
3
6
7
4
5
6
3
2
6
1
Keys
1 Stainless steel FGR pipe, insulated
2 Burner
3 Boiler
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
7 Stack
8
PT1000
Flue gas temperature probe
Summary of Contents for H365X
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Page 49: ...Siemens LMV5x Service Manual M12920CC rev 2 1 08 2017...
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Page 60: ...12 2 2 LMV5x program structure...
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Page 96: ...Note Specifications and data subject to change Errors and omissions excepted...
Page 98: ...Annex1 Example for motor cable...
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Page 100: ...Annex 2 Example for sensor cable...
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