Riello 20162652, Инструкции по установке, использованию и обслуживанию

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20162733 24 GB
Installation
5.11.1 Flue gas recirculation line sizing
The Tab. J can be helpful to correctly size the FGR pipes taking
flue gases from boiler stack base up to the burner intake port.
Maximum allowed pipe length (considering smooth steel pipes) is
specified for every burner and pipe diameter.
To prepare the Tab. J a flue gas maximum temperature of 260°C
was considered.
Tab. J
To account for the flow resistance at 90° elbows of the flue gas
circuit, the following equivalent straight pipe length values can be
considered, and shall be deducted from the maximum pipe length
values indicated in Tab. J to obtain the maximum length of FGR
pipe development in the considered instance:
Tab. K
Example for RS 510/E FGR:

foreseen overall pipe development: 24 m

foreseen number of bends: 3
Start considering a 6” pipe.
In Tab. J you see that maximum allowed length is 30 m, then we
must take off 3 x 4.5 = 13.5 m to account for bends.
We then obtain a maximum pipe value of 16.5 m.
You understand that pipe diameter is too small so we must
choose a 8” diameter.
Maximum allowed pipe length
FGR = 75 - (3 x 6.1) = 56.7 m that is > 24 m so it is fine.
5.11.2 Calculating the percentage of recirculated
flue gas
As a general rule, recirculated flue gas quantity must be adjusted
so as to recirculate the smallest quantity necessary to obtain the
required NOx rate.
Adjustment is carried out through the throttle valve located on
FGR pipe. It is necessary to consider that too high a quantity of
recirculated flue gas could lead to flame instability and excessive-
ly high CO rate.
To calculate the % of recirculated flue gas, use the formula be-
low: % IFGR= (CO
2
R
)/(CO
2
f
) x 100.
Where:

(CO
2
R
) is the percentage of CO
2
measured at the burner
coupling

(CO
2
f
) is the percentage of CO
2
measured at the stack
Diameter of FGR pipe
(inch)
RS 410/E FGR
(m)
RS 510/E FGR
(m)
RS 610/E FGR
(m)
3" - - -
4" 6.1 4.9 3
6" 45 30 24
8" - 75 61
Size of pipe
Pipe fittings
90° elbow (m) 45° elbow (m)
3" 2.2 1.2
4" 3 1.7
6" 4.5 2.4
8" 6.1 3.3