Micromod MOD: Modcell 2050R Users Guide - Manual (Page 194)

IB-23C650
RATIO BIAS CONTROL
A typical A/M Ratio Station application where a plant master steam flow
controller provides an input to two boiler masters (A/M ratio stations) is shown
in Figure 25.. Each of the two A/M Ratio Stations receive the same process
signal from the plant master but their outputs to the combustion control
system are different due to different ratios applied to their common process
inputs. This is done to balance boiler loading in an effort to optimize boiler
efficiency. In this example boiler number two is more efficient if run above
50% capacity. Boiler number one runs more efficiently between 40% and
50%. Boiler master number two receives a 45% input signal from the plant
master and a ratio of 1.1 is applied to achieve a 50% output. Likewise boiler
master number one receives a 45% input signal from the plant master but
here a ratio of 0.89 is applied to achieve a 40% output
Figure 25. Example of an A/M Ratio Station Application
Boiler
Master 2
Plant Master
Boiler #1
Boiler
Master 1
Boiler #2
45%
Process
Input
50%
Output
40%
Output
R=0.89 R=1.1
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