Flame Tube Parametric Studies for Control of Fuel Bound Nitrogen Using Rich-Lean Two-Stage Combustion.

摘要

A flame tube was used in experimental parametric studies of two-stage, rich-lean combustion to evaluate techniques for minimizing the conversion of fuel-bound nitrogen to nitric oxides in a premixed, homogeneous combustion system. Air at 670 exp 0 K and 0.48 MPa was premixed with fuel blends of propane, toluene, and pyridine, then burned at primary equivalence ratios of 0.5 to 2.0 and secondary equivalence ratios of 0.5 to 0.7. These fuel mixtures were proportioned to yield hydrogen compositions of 9.0 to 18.3 wt % and fuel nitrogen compositions of 0 to 1.5 wt %. Two distillates of a coal syncrude produced by the SRC-II process also were tested for NO/sub x/ emissions and the results compared with the propane-toluene-pyridine data. In addition to oxides of nitrogen, the exhaust gas was sampled for carbon monoxide, carbon dioxide, unburned hydrocarbons, and smoke. Rich-lean two-stage combustion was successful in reducing the conversion rate of fuel-bound nitrogen. Rates of less than 10% were observed for the optimum primary equivalence ratios, which ranged between 1.4 and 1.73 with a secondary equivalence ratio of 0.5. Fuel hydrogen and nitrogen content both influenced the values at which the optimum primary equivalence ratio occurred. The amount of fuel-bound nitrogen also affected conversion rate, since the conversion rate dropped as fuel nitrogen content increased. Exhaust NO/sub x/ levels, however, still increased with additional fuel nitrogen. (ERA citation 05:020026)