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Show FLASHCHAIN's chemical reaction mechanism for N-species evolution resolves the partitioning among char-N, tar-N, and HCN (Niksa 1995). A broad range of coal rank is evident in the evaluation of FLASHCHAIN predictions in Figure 3. These are reported and predicted nitrogen distributions at the end of primary devolatilization after very rapid heating. The predicted char-N levels correctly exhibit the minimum nitrogen retention observed for hv bit coals and are within experimental uncertainty for all coal types. Again, the predicted tar-N levels are within experimental uncertainty for all coals except the sample with 89% C, correctly exhibiting a maximum for hv bit coals. The lone discrepancy is because the tar yield for this coal is badly under predicted, as 16 vs. 27 wt. %. The HCN yields are also reliable except for the subbituminous coal that apparently releases NH3• Clearly, FLASHCHAIN accurately predicts the retention of nitrogen in char, and the partitioning of volatile-N between tar and noncondensibles for coals across the rank spectrum at the operating conditions of greatest technological interest Such resolution provides more information than is currently incorporated into coal-N conversion mechanisms in combustor simulators, which paves the way for more advanced formulations. c Q) ()) g 0.8 Z 0.6 (ij o () -o c 0.4 o ~ o ns ~ u.. 0.2 Nitrogen Evolution for Various Coals • .............................. v. .. . ........ ~. T ....... . ~..... ... ····· .... T T RT " V" 'R T " ,~ T ' ~ r:it--.~ ----.- ;-_ ---B-~ Tar o~~~~--~~~~~~~~~~~~~~~~~ 65 70 75 80 85 90 95 . Carbon Content, daf wt 0/0 Figure 3. An evaluation of FLASHCHAIN predictions against the char-N (e), tar-N (V), and HCN (_) monitored at 15,000 K/s from several coals. FLASHCHAIN predictions appear as the open symbols connected by curves. 5 |