13
Operation
Fuel-air Compound Control
Hydraulic Diagram
Fuel-air compound control
This compound pneumatic control
system with precision-adjustment capa-
bility has been designed to allow the
fuel and air flow rates to be steadily
varied in sliding mode for an adjustment
of the fuel-air ratio over the whole con-
trol range.
In the two-stage sliding control concept
the partial-load and full-load positions
are within the control range. Depending
on the heat demand these two load
points will be selected in sliding mode.
A larger fuel feed will not be suddenly
turned on or off. In the stepless control
mode the load will be controlled at any
point within the control range depending
on the heat demand. The two-stage sli-
ding and the stepless control concepts
are different only in the control systems
used with the burners. The same mode
of operation is used for both versions.
Electronic compound control:
The air box includes an actuator for
operating the air damper. The oil control
valve incorporates an actuator for adju-
sting the return oil flow rate and thus the
output of the burner.
The actuators for the air and fuel flow
control will be operated depending on
output by the electronic compound con-
trol which will move them into the pro-
grammed positions.
Electronic compound control
Oil
feed
Oil
return
Air
1a
Oil control valve with actuator
1b
Air dampers with actuators
2
Burner
3
Boiler
4
Combustion air fan