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Show SR1=0.9 for oil and lOON, the TFN begins to rise dramatically because of HCN and NH 3formation, but the percent conversion continues to decrease (SR1=0.7-0.8 for 30NT). Thus, in general, there exists two first stage stoichiometries with identical TFN levels (e g 300 ppm for oil) but with vastly different conversion efficiencies (41% versus 23%) and, hence, different exhaust emission. Impact of fuel properties on NO emissions The results in Figure 10 show data for three fuels, with 0.2, 2.99 and 9.5% fuel nitrogen, as the percent of the TFN exiting the first stage which wa$ converted to NO in the second stage. As the TFN concentration increased (due to decreasing SRI), the percentage conversion decreased. 100 EI v- 1217.6302*x"'-O.6<419 R-O.8S ~r-----------------~ i SIll - I I o C ~~------~~~----~ 200 300 _ Z "to .)~ €~ c: ~~ • .r-----------------~ ! c)~~ € ~ ~ u • 0.7 0 .. ..- o.s ",DI1(O- ry. Olan 2DOOO Figure 9. Influence of first stage exit composition on second stage NO. .~ 0 eo z N EI 104 • 0 Z M 0 )cC· 60 e~ 0 f E lol ~ • «I ~ :. o· c ~ z u0 C M i: 102 • n.r . ~1 20 • ~. SRl~.7 lit • ~. SAO-l • fAI. S.1 a • E,.52 0 - 101 0 5000 10000 15000 20000 0 .. 6 II SF .. IN ppm XNI (Dry, 0 102) Figur 10. Conversion of TFN to exhaust NO. Figur 11. The effect of fuel-N on exhaust NO. This behaviour is analogous for all three fuels and TFN correlate only with total nitrogen content for liquid fuels. Figure 11 shows theoretical calculated, predicted and measured minimum exhaust NO as a function of total fuel nitrogen content for all six liquid fuels. Results of the theoretical calculations was obtained from the combustion calculation with use of ultimate analysis for fuels, and stoichiometric ratio SRO=l without staged combustion. 7 10 |
