SYSTEM AND METHOD FOR MINIMIZING NITROGEN OXIDE (NOX) EMISSIONS IN CYCLONE COMBUSTORS

摘要

A method and system of minimizing nitrogen oxide emissions is disclosed. A boiler is provided with a slagging cyclonic combustor (2) at a lower region of a combustion zone (10). A carbonaceous fuel, an air stream and an oxygen stream are introduced into the combustor (2) with a multi-hole, secant oxygen injector. The oxygen stream (5) provides about 2 to 15 percent of the oxygen flowing into the boiler. The carbonaceous fuel is combusted at a stoichiometry of less than about 1.0 reducing oxidation of nitrogen-carrying species in the combustion products. An over fire air stream is introduced via an over fire air port into an upper region of the combustion zone contacting with the combustion product in the upper region and substantially completing the combustion process at a stoichiometry above about 1.0 and producing a flue gas.