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PILOT-SCALE DEVELOPMENT OF A LOW-NOX COAL-FIRED TANGENTIAL SYSTEM
Citation:
Kelly, J., R. Brown, E. Chu, J. Wightman, AND R. Pam. PILOT-SCALE DEVELOPMENT OF A LOW-NOX COAL-FIRED TANGENTIAL SYSTEM. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/7-81/137.
Description:
A 293 kWt (1 million Btu/hr) pilot-scale facility was used to develop a low-NOx pulverized-coal-fired tangential system. Conventional tangential system burner and vortex characterization tests defined the major system design requirements for a low-NOx system. Given these requirements, a burner concept was developed which achieves low NOx by directing the fuel and a fraction of the secondary combustion air into the center of the furnace, with the remaining secondary combustion air directed horizontally and parallel to the furnance walls. Such separation of secondary combustion air creates a fuel-rich zone in the center of the furnace where NOx production is minimized. This combustion modification technique has lowered NOx 64%, relative to conventional tangential firing, by injecting 85% of the secondary air along the furnace walls. Under these conditions, NO emissions were 180 ppm corrected to 0% 02. Also at these conditions, CO, UHC, and unburned carbon emissions were less than 40 ppm, 3 ppm, and 2.4%, respectively, comparable to conventional tangentially fired pilot-scale results. Also, the modification places a blanket of air on the furnace walls which reduces wall corrosion and slagging. With the modification, 02 concentrations above the burner level (near the furnace wall) were 12%, nearly three times conventional tangential pilot-scale system wall oxygen concentrations.