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INFLUENCE OF COAL COMPOSITION ON THE FATE OF VOLATILE AND CHAR NITROGEN DURING COMBUSTION
Citation:
Chen, S., M. Heap, D. Pershing, AND G.B. Martin. INFLUENCE OF COAL COMPOSITION ON THE FATE OF VOLATILE AND CHAR NITROGEN DURING COMBUSTION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-83/032.
Description:
The paper gives results of burning 50 coals from North America, Europe, Asia, South Africa, and Australia in a 21 kWt refactory-lined tunnel furnace to determine the influence of coal properties on the fate of volatile and char nitrogen. Excess-air fuel NO emissions (determined by combustion in Ar/O2/CO2) ranged from 415 to 1380 ppm with a premixed burner. These results correlated with total fuel nitrogen, inert pyrolysis HCN yield, and non-volatile nitrogen content, rather than with the geographic origin of the coal. Minimum staged NO emissions (at optimum first stage stoichiometry) ranged from 140 to 380 ppm. Detailed in-flame measurements indicated that, as first stage stoichiometry (air/fuel) was reduced, first stage NO formation decreased, but was ultimately offset by increases in oxidizable gaseous nitrogen species and solid phase nitrogen retention. TFN (NH3 + NO + HCN) generally increased with increasing fuel nitrogen, and the species distribution depended on coal rank. In general, HCN was greater than NH3 with bituminous coals, but less than NH3 with subbituminous and lignite coals. Second stage TFN conversion to exhaust NO decreased as the TFN distribution was shifted in favor of HCN and NH3. Char nitrogen conversion was generally low (less than 20%).