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Show DISCUSSION AND CONCLUSIONS Table 1 shows a comparison of the base NOx (without FGR) and adiabatic flame temperature for several fuel compositions. As would be expected, the table shows that the NOx emissions increase as the adiabatic flame temperature increases. The emissions also appear to be very sensitive to flame temperature, since they increase by 33%, from 27 PPM to 35, with only a 130°F increase in adiabatic flame temperature. Table 1 Flame Temperature and NOx for Various Fuel Gases without Flue Gas Recirculation Flame Temp. J-IV NOx,(3%02) of H" PPM Natural Gas 40% H2 I 30% C3H8 I 30% Nat. Gas 50% H2 I 50% Nat. Gas 40% H2 I 30% C3H6 I 30% Nat. Gas 3385 / v"5 7 3450 /6 7'7 3465 C,"7 3515 11 3 ~ 27 28 32 35 Another interesting finding is that, except for the propene fuel mixture, a higher rate of flue gas recirculation was required to achieve a given percentage reduction in NOx for the refinery fuel gas mixtures compared to the natural gas fuel. This is shown by the lower slope of the NOx versus FGR curves for the mixed fuel gases. The variation in response to FGR between the different fuel compositions is also sufficient enough to require that data must be collected for a wide variety of fuel compositions in order to allow accurate prediction of emissions. In summary, the data show that it was possible to meet the SCAQMD Rule 1146 NOx emission limit of 40 PPM utilizing the SFR burner without FGR when using ambient air. The Rule 1109 NOx emission limit of 0.03 Ib/MMBtu was easily met using the SFR burner with FGR. These test results have also been confirmed by recent measurements made in a process heater in a refinery in the Los Angeles area. 11 |