Fgr Commissioning - Riello DB 4 SE FGR Installation, Use And Maintenance Instructions

5.9

FGR commissioning

The flue gas recirculation (FGR) function is used to reduce the
NOx content of flue gases. This is accomplished by feeding a cer-
tain proportion of the flue gas back to the combustion chamber,
causing the flame's temperature to drop. The amount of recircu-
lated flue gas is set via auxiliary actuator 3.
When making the setting, it must be observed that
excessive amounts of recirculated flue gas can
cause the flame to lift off the burner's head (stabil-
ity limit of flame).
WARNING
NOTE:
Reduction of maximum burner output
Use of the flue gas recirculation (FGR) function or the flue gas
mass introduced to the supply air duct might lower the burner's
maximum output.
This means that the maximum amount of combustion air that can
be introduced will be reduced.
Hence, the amount of fuel for high-fire operation must be reduced
to ensure correct combustion values.
The control box supports flue gas recirculation (FGR) function:
flue gas recirculation (FGR) without temperature compensation
(operating mode flue gas recirculation (FGR) = time or tempera-
ture).
With these operating principles, the positions of auxiliary actuator
3 can only change between CLOSED (ignition position) and the
positions on the ratio control curves.
First time set up
Commission the plant with no influence from flue gas recircula-
tion (FGR).
Factory preset: FGR-Mode = AUX3onCurve
Flue gas recirculation (FGR) function is deactivated.
(Auxiliary actuator 3 is driven along its parameterized ratio control
curve)
This enables the fuel-air ratio control system to be set as if the
plant operated without flue gas recirculation (FGR).
For that purpose, in flue gas recirculation (FGR) mode Time, set
the switch-on time to its maximum or parameterize it at such a
level that auxiliary actuator 3 will not be positioned until the curve
settings become active.
Analogously, in flue gas recirculation (FGR) mode Temperature,
set the switch-on temperature to a level that cannot be reached.
After completing the settings of the fuel-air ratio control curves
without flue gas recirculation (FGR), the actual settings with an
active auxiliary actuator 3 can now be made.
Since this might have an impact on the combustion settings, the
fuel- and air-regulating actuators may have to be readjusted.
First time FGR set up
Modify the factory preset: FGR-Mode = time (Auxiliary actuator 3
is held in the ignition position until an adjustable time is reached).
We suggest to use a value from 5-15 minutes for first time FGR
commissioning.
Check value of temperature of flue gas recirculation (FGR). It
must be 120-130 °C to reduce condensation in burner or intake
duct.
Start-up, calibration and operation of the burner
Operation FGR set up
Modify the factory preset: FGR-Mode = temperature (Auxiliary
actuator 3 is held in the ignition position until an adjustable tem-
perature is reached.).
After first time FGR commissioning, we suggest to use this set-
ting using a temperature sensor in FGR duct.
We suggest to use previous value of temperature measured dur-
ing first time commissioning.
In case of use the FGR-Mode = time, make sure that the flue gas
temperature reaches the value within the set time.
FGR temperature sensor
FGR-Mode: PT 1000 temperature probe is connect to X11 termi-
nal (see electrical connection)
You can connect 2 probes in X10 terminal together:
Factory pre-set:
PT100 for boiler temperature (customer installation)
PT1000 for FGR-sensor (already connected)
You can't use PT1000 probe for boiler tempera-
ture when it's used as FGR sensor. But you can
use other type of connection.
Check air temperature where is mounted flame
sensor.
If temperature is more than 50-60°, it's mandatory
WARNING
air cooling using burner air-intake.
While burner is working with FGR, it's possible
reach high surface temperature.
27 GB
20169009