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Show surfaces or outside of the furnace, the N O x concentration declines in conjunction with increasing CO. N Ox declines because of flame quenching and, Figure 5. NOx VARIATION WITH LOAD. therefore, lower temperatures. CO increases because of flame quenching, and also, because the C O in the cold wall boundary layers becomes kinetically frozen and ceases being further oxidized before leaving the boiler. The second example can be seen in the comparison of the PRECISE C O curve and N O x curves for the flame which results from designing the flame by analysis. The N O x is the minimum, without forcing C O excessively high, for the selected burner type and application parameters; gross heat input, volumetric loading, combustion air temperature, non-cooled surface area, furnace proportions, diluents, etc. GENERALIZED NOx BEHAVOIR Figure 6 is a first time published, full domain generalization of N O x yields from high nitrogen oils, low nitrogen oils and natural gas over the full range of furnace exit oxygen concentrations. It is applicable to analytically designed flames without F G R or any other upstream N O x suppression methods, and for aerodynamically clean, low excess air, diffusion flame, mixing rate limited burners. This is one of a collection of generalized N O x plots. The others include the effects of FGR, FBN, volumetric heat input, draft loss and multiple burner interactions. There are three curves for each fuel, for ambient temperature, 190 and 320 C combustion air. The shape of the curve is most revealing. There is a clear bend in the data with the low oxygen end of the curve trending toward zero N O x at zero boiler outlet oxygen. It is apparent that all three fuels have similarities in the relationship of N O x to oxygen leaving the flame. In nonhomogeneous mixtures of combustion reactants, the equilibrium N O x concentrations in the fuel lean zones is not zero. Zero N O x in a stoichiometric mixture is only theoretically required at chemical equilibrium when the combustion products are BOILER OUTLET '/. 02 Figure 6. NOx DEPENDENCY on FLAME EXIT 02. perfectly stirred. Therefore, it can be concluded that N O x formation in stoichiometric mixtures in this class of imperfectly stirred, diffusion limited, swirl stabilized burner is not precisely zero, but is quite low. The higher temperature data shows that N O x formation at greater oxygen concentrations leaving the flame increases at a decreasing rate as both total N O x and oxygen increase. Figure 7 extends the range of temperature applicability of the general N Ox relationships in Figure 6. Figure 7 is a plot of N O x versus combustion air temperature for ultra-high temperature combustion air without F G R using natural gas [10]. The high temperature data confirms that it is accurate to extend the high temperature portions of these curves to much higher temperature applications. FBN YIELD EFFICIENCY Figure 8 is a plot of NOx versus FBN mass percent in the fuel. The curve labeled 100 % FBN Conversion is accurate for only one set of conditions. That condition is satisfied when 100 percent of the atomic nitrogen in the liquid fuel is chemically converted to N O and when 110 percent theoretical air is included in the reactants. The error for inclusion of some or all of |