Environmental Engineering Reference
In-Depth Information
combustion amount was conducted by identifying the models with respect to the
damper, the rpm of the exhaust gas fan (variable voltage, variable frequency, or
VVVF), and the combustion amount.
The simulator is a Proportional Integral Derivative (PID) controller for feedback
control. Two operation terminals for the furnace pressure damper and the rpm of
the exhaust gas fan are involved. A subsystem to branch the control output is
necessary. Several methods are available for this purpose. The split control method
was employed, in which the low-rpm region of the exhaust gas fan is controlled by
the damper and the rpm of the fan will assume control after the damper is fully
opened. Thus, the damper and VVVF were modeled separately in this case.
The results of the simulation with the combustion amount of the simulator shown
in
Figure 5.55
reduced from 50 to 28% are shown in
Figure 5.56
.
The simulator
was set so that the output within 30% would be controlled by the damper and the
output above this figure would be controlled by VVVF, while the damper was set
to be fully opened at the 70% level. The figure clearly illustrates the alternate control
yout
To Workspace
Mux
Parameter
P:0.7
I:0.80
D:0.2
Step Input 2
output
0.00385
s+0.014
+
50
Set point 2
COG
Step Input 1
-
-
0.0122
s+0.0175
+
+
Saturation 2
-
3
PID
Controller
Gain
1
Pressure
(mmH2O)
VVVF
Set point 1
0.0048
20.3095
Subsystem
s+0.0185
offset
Saturation 1
Damper
FIGURE 5.55
Simulation of changing combustion amount.
100
5
80
4
Damper
60
3
40
2
CV
20
1
VVVF
0
1000
0
1000
1200
1400
1600
1800
2000
1200
1400
1600
1800
2000
Time, s
Time, s
FIGURE 5.56
Results of simulation.
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