NO_X reduction using coal pyrolysis gas as reburn fuel: Effects of pyrolysis gas composition

This chapter discusses the reburning efficiency of a pyrolysis gas produced in an entrained flow or fluidized-bed reactor. Pyrolysis experiments are performed for a series of Australian and German coals and combustion studies in a two-stage fuel splitting and staging reactor. Fuel staging or reburning is an efficient method to reduce NO_x emissions from bituminous and brown coals. With coal pyrolysis gas as reburn fuel, the NO_x reduction is improved. The German emission standards of 200 mg/m³ at 6% oxygen (O₂) are achieved at the test facility. The optimum pyrolysis temperature for brown coal maximum NO_x reduction is determined at 800°C. At this temperature, the pyrolysis gas contains maximum concentrations of tar, hydrocarbons, and ammonia (NH₃).