Riello 20155654, Installation, Use And Maintenance Instructions

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31 20155699 GB
Start-up, calibration and operation of the burner
6.4 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 channel 3.
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.
With these operating principles, the positions of actuator’s chan-
nel 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).
This enables the fuel-air ratio control system to be set as if the
plant operated without flue gas recirculation (FGR).
After completing the settings of the fuel-air ratio control curves
without flue gas recirculation (FGR), the actual settings with an
active actuator’s channel 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
Actuator’s channel 3 is held in the ignition position until an adjust-
able time and temperature are reached.
Check value of temperature of flue gas recirculation (FGR) during
operation mode. It must be 100-130 °C to reduce condensation
in burner or intake duct.
Operation FGR set up
Actuator’s channel 3 is held in the ignition position until a delay
time and an adjustable temperature is reached.
After first time FGR commissioning, we suggest to setup the con-
trol box FGR delay time.
Use a value from 5-15 minutes.
Also check temperature sensor FGR make sure that the flue gas
temperature reaches the value within the set time.
If necessary, you can adjust BT 330 FGR temperature with a star-
ting value.
Default factory time: 300 sec
Default FGR temperature: 50°C
WARNING
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
Check air temperature where is mounted flame
sensor. If temperature is more than 50-60° the
flame sensor can be damaged.
While burner is working with FGR, it's possible
reach high surface temperature.