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Show 35 30 25 Ec. 20 ,e; )( 0z 15 10 5 0 APPROACH 0 o 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 CO (ppm) Figure 1: N Ox and CO Trade-off The first step of the approach is to establish and utilize a burner which represents design features typical of practical, industrial applications but incorporates flexibility that is attractive for research study. The second step is to establish a fuel and air mixing strategy that provides a systematic variation in mixing effectiveness. The third step is to operate the burner at one load condition, vary the fuel mixing processes, and assess the impact on (1) the emission of NOx and (2) the overall combustion efficiency. The fourth step is to establish a methodology for tracking the burner performance (in tenns of NOx emissions and combustion efficiency) and identify the operating conditions that yield the more typical "adverse" response (i.e., reduced NOx emissions accompanied by degraded combustion performance) and those select conditions, if any, that yield a "favorable" response (i.e., reduced NOx emissions accompanied by high combustion efficiency). The fmal step is to conduct in-situ measurements (such as laser anemometry) to lend insight into the processes that produce the "favorable" response in contrast to the "adverse" response. EXPERIMENT BURNER AND FACILITY The model, industrial burner, shown in Figure 2, is upfrred with natural gas at 100,000 BtuIhr and coaxial air. The burner was specially designed, with industrial advice, to provide dimensions and an overall configuration typical of practical systems while retaining parametric flexibility in both the geometry and overall operating conditions. The principal flexibility in operating conditions are, for a given load, the excess air and the swirl strength (S') . . Air is provided to the burner via two air streams, the axial air stream and the swirl air stream. The total flow of air and 2 |