Riello 20171510, Installation, Use And Maintenance Instructions

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20171652 20 GB
Installation
4.9.1 Flue gas recirculation line sizing
The Tab. K can be helpful to correctly size the FGR pipes taking
flue gases from boiler stack base up to the burner intake port.
NOTE:
The typical recirculation percentage is between 10% and
15%.
A low recirculation percentage might cause a high Nox level.
A high recirculation percentage might cause flame instabili-
ty and a CO level higher than normal.
4.9.2 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
Tab. K
4.10 Burner closing
Once the combustion head adjustment is completed:

reassemble the burner on the guides 3) at about 100 mm
from the pipe coupling 4) - burner in the position shown in
Fig. 15;

insert the electrode cable, then slide the burner as far as the
pipe coupling - burner in the position shown in Fig. 19;

connect the plug of the servomotor 14)(Fig. 15 on page 17);

connect the socket of the maximum gas pressure switch;

refit the screws 2) on the guides 3);

fix the burner to the pipe coupling with the screws 1).
Burner output
kW
Flue gas pressure at test
point 6)(Fig. 18) - mbar
RS
6
8
/E
F
G
R
350 -0.8
400 -1.1
450 -1.3
500 -1.6
550 -1.8
600 -2.1
650 -2.4
700 -2.6
750 -2.9
810 -3.2
RS 1
20/E F
G
R
595 -1.8
650 -2.1
700 -2.4
750 -2.7
800 -3.0
850 -3.4
900 -3.7
950 -4.1
1000 -4.3
1100 -4.5
1150 -4.6
WARNING
When fitting the burner on the two guides, it is
advisable to gently draw out the high voltage
cable until it is slightly taut.
1
4 3 2
Fig. 19
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