Alternative fuel reburning

Advanced reburning is a NOx control technology that couples basic reburning with the injection of nitrogen agents and promoter compounds. Pilot scale experiments were conducted in which efficiency of basic and advanced reburn ing processes were characterized with a wide range of reburn fuels. Test fu els included natural gas, pulverized coal, coal pond fines, biomass, refuse derived fuel, and Orimulsion, Process variables that were studied included reburn fuel type, reburn fuel heat input, reburn zone residence time, init ial NOx concentration, nitrogen agent injection temperature, and promoter t ype and amount. Reburn fuel properties found to affect the performance most significantly include fuel nitrogen content, volatiles, and ash constituen ts. Basic reburning performance for the tested solid fuels was found to app roach that of natural gas reburning, with over 70% NOx reduction achievable at reburn heat inputs above 20%. Advanced reburn tests were conducted in w hich reburning was coupled with injection of nitrogen agents and promoters. The most effective promoter compounds were found to be alkalis, most notab ly sodium compounds. At reburn heat input of 10%, NOx reductions in the ran ge of 85%-95% were achieved with natural gas and biomass advanced reburning . (C) 1999 Elsevier Science Ltd. All rights reserved.