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Show The Type 4 signal provides an indication of flame stability by responding to the flame disturbances, changes of load or excess air. Our extensive boiler and burner testing led us to believe that most of the required information can be extracted from the flame fluctuations in the ignition zone. During the current project, we sought such signal processing algorithms which would enable us to form these four types of output signals. Figures 2 through 10 present test results. The BDS (and the derivative Ff and FP systems) offers extensive possibilities for creating and studying new algorithms and ' their combinations. We identified several calculated statistical values (algorithms) possessing the potential to fonn the required output signals. We concentrated on several calculated signals in each group which at present appear to be the best parameters. Type 1 Signal. We conducted detailed analysis of various candidates for creating an effective Type 1 signal, which is probably the most important signal. Figure 2 illustrates several signals (No.8, 10, 15, and 16; each representing various calculated statistical values) as a function of air flow at different loads. We selected the two signals No. 15 and 16 which provided the most stable, sensitive, and repeatable response to changes of air flow or air-fuel ratio. Figures 3a and 3b show two examples of correlation with air flow. With regard to Nox, please notice that for this particular burner at constant load, NOx is consistently proportional to the air flow. Figure 4 illustrates correlation between NO and air flow at different loads. Normal Operating Range I I , AirFlow vo~~ ~e'{ " .. ~'S I ~~~e I Normal Operating Range '-- ~ " Burner Load Figure 1. Desired Output Signals Our next step was to fmd the optimum tuning parameters for the selected signal. These tuning parameters include proper fIltering, the value of coeffIcients used in the algorithm calculations, and the frequency band. After selecting these optimum tuning parameters, we concluded that although some variations in the tuning parameters existed, they were not critical, and the signal worked well in the broad range of their values. Type 2 Signal. We reviewed and analyzed various candidates for the Type 2 signal. Initially, we identified the two signals No. 13 and 18 to correlate with CO (Figures Sa and Sb). However, 4 |