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Show For example, FLASHCHAIN has already been incorporated into a PC-Based software package developed by EPRI that estimates NOx emissions in the exhausts of full-scale utility boilers. As depicted in Figure 6, the structure of the calculation is straightforward. The user provides a few measured values of NOx emissions and describes the major furnace operating conditions, such as the firing configuration, the type of NO x control technology, the firing capacity, etc. The user also enters the proximate and ultimate analyses for the coal that was fired while the data was recorde<L as well as those for any coals that he or she wants to screen. This computer program then predicts the NOx emissions for the set of coals being screened when they are burned under the same firing conditions as were used when the data was collected. In this program, FLASHCHAIN is used to predict two critical characteristics that relate coal properties to NOx emissions: First, it predicts the total amount of volatiles driven off the coal while it is being heated under flame conditions, where heating rates approach lOs Kls and temperatures approach 3000 OF. The weight loss under flame conditions typically exceeds the proximate volatile matter contents by 20 to 100 %, which explains why NOx emissions do not correlate very well with fuel ratios determined from typical ASTM proximate analyses. The second critical infonnation from FLASH CHAIN is the partitioning of fuel-nitrogen species among gaseous pyrolysis products and char. This partitioning is important because only the chemistry involving gaseous nitrogen compounds can be affected by aerodynamic NOx abatement strategies that regulate mixing to achieve relatively reducing conditions at moderate temperatures. Current Coal Properties: Coal A Current NOx Emissions: Coal A Alternate Coal Properties: CoalS Flashchaln Model Rgure 6. Structure of EPRI's NOx LOI Predictor Program. 10 NOx Correlations Predicted NOx emissions for Alternate Coal CoalB (same firing conditions as Coal A) |