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Show 0.67 NOEX = 0.87*SR1*(NO)+ (HCN+NH3 )+ 1 1+0.004(HCN+NH3 ) + 0.27(1-SR1)~(char N) (Eq.2) where all concentrations are ppm dry, corrected to stoichiometric conditions. As with equation (1), this nonlinear regression equation correlates well with experimental data from staged combustion of fuels with 0.2, 2.8 and 9.5% fuel nitrogen well in spite of extremely complex controlling processes involved in staged combustion. CONCLUSIONS Data have been presented showing the impact of fuel properties on NO formation from liquid fuels under both excess air and staged conditions. Investigations of fuels with a wide range of percent wt fuel nitrogen indicate that: 1 Fuel NO formation from liquid fuels can be correlated with the total fuel nitrogen content and with inert pyrolysis HCN yield under excess air conditions. 2 The results of this investigation with six fuels indicate that NO emission can be correlated by the TFN entering the second stage of combustion under staged conditions. 3 The distribution of TFN species in the first stage depends heavily on percent fuel nitrogen. In general, HCN is greater than NH 3 . 4 NO control for high nitrogen fuels is most effective when a rich primary zone is held at an optimum stoichiometry to minimize both the TFN concentration and the TFN conversion to NO in the second stage flame. The second stage conversion decrease with increasing unburned hydrocarbons content. 5 Increased NO reduction was attained at longer first stage zone residence times when firing all fuels. The mechanism believed to be responsible for this conclusion was a hydrocarbon reduction of NO in the fuel-rich staged zone. This reduction of NO depleted the reactive nitrogen pool (TFN) entering the burnout zone which lowered the conversion of TFN to NO excess in the burnout zone. 6 The behaviour of fuel NO formation has been similar for all fuels tested, and correlated with data obtained from high reactive volatile matter coals. This work addressed only global mechanisms in the staged and in the post flame, at long time scales, and says nothing about XN and NO formation mechanism occurring at short time scales. The latter are, of course, important, since they control the initial condition for the destruction of nitrogenous species in the first stage of a staged combustion. ACKNOWLEDGEMENTS This work was funded by Studsvik Energy as part of an inhouse basic research program. 9 |