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Show Also, a small amount of flue gas recirculation has a more dramatic effect on NOx emissions than a significant amount of fuel staging, as predicted by the chemical kinetics modelling. There are, however, diminishing returns as the amount of flue gas recirculation is increased. This is seen more clearly in Figure 9, in which measured NOx emissions for a fixed excess air level (15%), firing rate (1.0 MW or 3.5 MMBtu/hr) and degree of fuel staging is plotted as a function of flue gas recirculation rate. Finally, Figure 10 shows the optimized emissions performance of the burner as a function of fIring rate. The measured NOx emissions were below the program goal of 15 ppm at all operating conditions, though there was a slight upward trend with firing rate, as would be expected. Integrated ChillerlBurner Test Results: Testing of the prototype 10w-NOx chiller burner in a 300-ton chiller was completed at Trane's laboratories. Figure 11 shows the prototype burner installed in the chiller combustion chamber at Trane. A summary of key results is provided in Table 2. NOx emissions data from the Trane Company integrated chiller tests are plotted for comparison with the data from the Power Harne water-cooled combustion chamber tests in Figure 9. The agreement between the two sets of data is excellent, indicating that the difference in combustion chamber geometry and wall temperatures between the two tests had an insignificant effect on burner perfonnance. The burner met all of the project performance goals: NOx levels were between 11 and 15 ppm, CO emissions were below 20 ppm, and the combustion chamber thennal efficiency was comparable to that obtained with conventional burners. Table 2. Summary of Integrated Chiller/Burner Performance Thermal '_,E~ , "% Cooling: High-Fire 3.5 3.9 15 18 82.8 Cooling: Mid-Fire 2.6 5.1 11 16 832 Cooling: Mid-Fire 1.7 6.2 11 10 84.1 Cooling: Low-Fire 1.2 6.8 12 18 83.9 Conclusions Under the support of the Gas Research Institute, Arthur D. Little, Power Harne and The Trane Company have developed and demonstrated an innovative 10w-NOx burner 16 |