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Show Thermal Reference Test Input Scale Do Site 106 vV 106 BTU/hr mm Location Primary test scales (burner/furnace similarity) 0.03 0.1 27 Michigan 0.3 1.0 87 Michigan 1.3 4.4 181 IFRF 4 13.6 318 IFRF 12 40.9 549 John Zink Co. Secondary test scales (confinement effects) 0.3 1.0 87 BERL Table 1: The five principal burner scales in the SCALING 400 test series, spanning a factor of 400 in thermal input. Shown are the burner thermal input at full load conditions and the combustion air duct diameter Do for each scale. The additional 300 k W scale measurements at BERL examined effects of varying geometric and thermal conditions. During the past two years, the analysis portion of the SCALING 400 study has been underway at The University of Michigan. Data from all five primary burner scales, as well as from additional tests under conditions of lower confinement, have been examined in detail. From this, new insights have been obtained into the N Ox generation mechanisms in typical industrial burners and furnaces. These insights have been used to develop a physically- based burner scaling model relating the N Ox emission performance of smallscale burners to full industrial scales over a wide range of thermal inputs, staging ratios, excess air dilution levels, and combustion air temperatures. This paper summarizes results from these scaling analyses and presents the burner scaling model. The presentation is organized as follows. In §2 we briefly summarize the burner and furnace geometries and operating conditions used in the SCALIN G 400 tests. Following this, §3 presents N Ox emissions performance data from all burner scales over the entire range of operating conditions. In §4 we then develop the burner scaling model, and in §5 present comparisons between actual burner performance and predictions from the scaling model under the assumption of perfect geometric, aerodynamic, and thermal sirnilarity across all burner scales. In §6 we introduce corrections to account for departures from perfect similarity in the SCALING 400 tests. Conclusions are then drawn in §7 as to general principles governing industrial gas burner scaling and the utility of the burner scaling model presented here. 2. BURNERS AND FURNACES The swirl-stabilized burners used in the SCALING 400 test series were all geometrically identical to that shown in Fig. 1, and varied only in size. The dimension of the com bustion air duct diameter Do at each burner scale is given in Table 1. The design represents a generic industrial gas burner, and allows for continuous variation in inlet swirl number a~d _~apabilities for han_dli!lg a~bien-t and preheated combustion air as well as fuel staging 3 |