211
8 CO/O
2
Control
8.6.3 Optimisation Strategy
The optimisation strategy includes searching for the optimum working point of the furnace
near the emission edge, adjusting this accordingly, maintaining it, optimising further, if neces-
sary, and monitoring.
To do this, the fuel-air mixture is dynamically modified without influencing the power control
unit in the direction of a lower lambda value (less air, more fuel). The beginning of incomplete
combustion is shown by a strong signal increase and signal dynamics.
From this point on, the air-fuel mixture is slightly modified again in the direction of a greater
lambda value (more air/less fuel). The optimum working point is found.
The working points determined in this way are subjected to a plausibility analysis. Working
points outside of this are discarded and recalculated. This procedure is repeated cyclically so
that the optimum working points are always maintained even in changing weather and system-
related conditions.
If the KS1D Combination probe detects unburned residue (CO/H
2
), for example as a result of
changed, system-specific conditions, the working point is immediately shifted in the direction
of a greater lambda value (more air, less fuel).
The simultaneously measured O
2
value is not required for CO control itself. It is only required
for monitoring and visualisation purposes. If it is not possible for combustion-related reasons
to run to the CO edge over the entire firing range, there is the option of switching smoothly
from CO control to O
2
trim depending on the firing range. With multi-fuel burners, you can se-
lect whether CO control or the O
2
trim is active depending on the fuel.
8.6.4 Advantages of CO Control over O
2
Trim
• Higher energy savings through continuous self-optimisation in every firing-rate point
• Better control performance through significantly shorter setting times
• Excess air independent
• Failsafe
• Higher operating safety
• Robust
• Low-maintenance
8.7 Operating Control and Displays
8.7.1 Is CO Control or O2 Trim Activated?
Factory settings
Oil ï‚® O
2
trim
Gas ï‚® CO control
P 100 AL 1 = 1 O
2
standard trim with optimisation curve
P 101 AL 0 = 0
1
O
2
trim OFF
O
2
trim ON
P 200 AL 1 = 1 CO controller type: Gas = CO control, oil = O
2
trim
P 203 AL 0 = 0
1
CO controller OFF
CO controller ON