40
•
The new filter assembly (part number LA220623) can then be inserted into the snout, beveled
side inwards.
•
The snout can be refitted, ensuring that the filter locates into the probe body. The retaining wash-
ers and nuts should be tightened sequentially to seal the filter assembly to the flange.
Probe Mounted Flue Thermocouple Replacement
•
Remove the oxygen probe from the flue as detailed in section 6.4.3.
•
Disconnect the internal connections to the thermocouple.
•
Unscrew the 2 thermocouple-mounting blocks from the probe snout to allow the thermocouple
to be straightened.
•
Remove the hexagonal nut securing the thermocouple into the probe and withdraw the thermo-
couple through the probe body.
•
Refitting is the reverse of the removal procedure. The electrical connection and polarity of the
thermocouple are detailed below.
SOx, NOx, Smoke, CO, AUX1, AUX2, O/P1, O/P2
The 6 inputs are isolated from the 2 outputs and the oxygen probe, however, they are not isolated
from each other.
The 2 outputs are isolated from the 6 inputs and the oxygen probe, however, they are not isolated
from each other.
Oxygen Trim Operation
With the oxygen trim system correctly commissioned and enabled, the unit will continually compen-
sate for changes in fuel and environment that affect combustion.
The trim system will continually monitor the flue oxygen level and attempt to maintain this as close
the desired oxygen level (oxygen setpoint) for the current point in the firing range.
Using air or fuel flow information entered into the unit at commission time, the trim drive motor will
be moved by an amount which will give the desired change in air or fuel flow, which then gives the
desired flue oxygen reading.
The adaptive algorithm used will then remember how much trim was applied at this point and next
time this firing point is reached, the same trim will be applied immediately without having to wait for
the oxygen value to change.
Trim is not applied if the unit is in commission mode.
Commissioning Oxygen Trim
WARNING: Use extreme care when entering flow values and oxygen set points. Incorrect
setting of either could cause a hazardous situation to occur.
If the flow values and oxygen set points have been up-loaded it is essential that the combus-
tion is verified at each firing position to ensure a hazardous condition cannot occur.
If using automatic oxygen trim commissioning it is the sole responsibility of the commission-
ing engineer to ensure the values calculated by the system are correct and will not cause a
hazardous condition to occur.
Once the oxygen trim is commissioned the trim flow limit must be set to ensure a fault in the
oxygen trim will not cause a hazardous condition to occur.
For the oxygen trim system to function correctly, the following information must be entered:
1.
Option parameters
2.
Flow values and O2 setpoints.
These values may be entered manually by the engineer, or the system can automatically calculate the
values and enter them itself (automatic trim commissioning).
