Patent ID: 8544394

Claim:
An apparatus for reducing the formation of nitrogen oxide on a primary side of a furnace and reduce or avoid nitrous oxide and ammonia slip in an offgas of the furnace, the furnace being configured to burn a fuel in a combustion process having at least two stages, the apparatus comprising: a combustion chamber including a grate disposed therein; a combustion bed configured to receive a primary gas including oxygen so as to burn the fuel on the grate, the combustion bed including a plurality of bed areas, each of the bed areas having a respective feed of the primary gas and a partial offgas stream; an offgas burn-out zone downstream from the combustion chamber configured for after-burning of incompletely burned offgas components; a secondary gas introduction device configured to introduce a secondary gas including oxygen into the offgas burn-out zone; and an injection device configured to inject a water-gas mixture as at least one free jet above a surface of the combustion bed upstream from the offgas burn-out zone so that the at least one free jet axially penetrates, over all the bed areas of the combustion bed, the partial offgas streams of all the bed areas and increases a temperature of the offgas above the combustion bed at a rear portion of the bed areas upstream from the downstream offgas burn-out zone.