Test results from an existing DOE-NETL funded program to evaluate performance of theAdvanced Layered Technology Approach (ALTA) in a pulverized coal-fired furnace arepresented. ALTA involves a synergistic combination of over-fire air (OFA) and burnermodifications, Rich Reagent Injection (RRI), and Selective Non-Catalytic Reduction (SNCR).The eventual goal of this program is to demonstrate at pilot-scale that the combination ofcombustion modifications, deeper staging, and RRI may yield NO_x emissions lower than thecombination of traditional low-NO_x burners with OFA. A key concept of this approach is thehomogenization of furnace gas composition within a deeply staged primary combustion zone toachieve NO_x emissions approaching thermodynamic limits. Results show that the chemistry ofNO_x reduction associated with RRI is valid in a PC environment. At long residence times, a NO_xconcentration of 62 ppm (0.061 lb/MBtu) may be reached at a burner stoichiometry of 0.85. Atshort residence times, RRI is ineffective when introduced into the stratified gasses generated by alow-NO_x burner, but up to 50% reduction of NO_x can occur when the burner is modified tohomogenize the combustion gases. It has also been demonstrated that at short residence times, acombination of burner modifications, staging, and RRI can produce lower NO_x emissions thanlow-NO_x burners and staging alone, to achieve NO_x emissions of 76 ppm (0.075 lb/MBtu).
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