초록 ▼

A method for controlling NOx in a multi-zone re-heating furnace used for meeting process heating (or re-heating) requirements in the metals industry. Oxidant-fuel stoichiometry is altered in different zones of a multi-zone re-heating furnace to reduce the overall NOx emission without replacing exist

A method for controlling NOx in a multi-zone re-heating furnace used for meeting process heating (or re-heating) requirements in the metals industry. Oxidant-fuel stoichiometry is altered in different zones of a multi-zone re-heating furnace to reduce the overall NOx emission without replacing existing burners or intrusively modifying the furnace (or drilling holes in the furnace) for fuel and/or an oxidant injection. The oxidant-fuel stoichiometry in at least one zone of a multi-zone re-heating furnace is made either oxidant neutral or oxidant deficient (or fuel rich) to reduce the formation of NOx and the oxidant-fuel stoichiometry of at least one other zone that is located downstream of the oxidant neutral or oxidant deficient zone is made oxidant rich (or fuel lean) to further reduce the formation of NOx in the furnace.

대표청구항 ▼

[ What is claimed:] [1.]1. A method for controlling formation of NOx in a metal heating furnace having a soak zone and at least two heating zones wherein metal to be heated moves through said heating zones and through said soak zone counter-current to combustion gases flowing through the furnace to

[ What is claimed:] [1.]1. A method for controlling formation of NOx in a metal heating furnace having a soak zone and at least two heating zones wherein metal to be heated moves through said heating zones and through said soak zone counter-current to combustion gases flowing through the furnace to a flue in said furnace, said heating effected by combustion of a fuel with an oxidant, comprising the steps of:operating at least one heating zone of said furnace so that said zone is one of oxygen neutral or fuel rich as determined by stoichiometry; andoperating at least one other heating zone of said furnace downstream of said one zone of said furnace oxidant which as determined by stoichiometry with an increase in oxidant content large enough in said one other heating zone of said furnace to maintain an overall oxidant rich oxidant-fuel stoichiometry in said furnace;whereby said flue gases from said one heating zone and said one other heating zone are mixed prior to exiting said flue, whereby NOx and CO formation in said flue gases exiting said flue are suppressed.