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AssigneeKrupp-Koppers GmbH
InventorsHeinz Durselen, Arnulf Schuffler, Gunter Meyer
Estimating the term…
The method of reducing a nitrogen oxides content of a flue gas generated on firing of a rich gas or combination coke oven having a plurality of heating walls forming dual heating flues, in which a single stage or multistage combustion takes place, and also having a plurality of regenerators for recovery of flue gas heat and preheating of an underfiring medium, includes the steps of mixing one portion of the flue gas drawn from one flue of the dual heating flues with the underfiring medium, gas and/or air, prior to or on admission to the other flue of the dual heating flues, or a regenerator connected with it, and circulating another portion of the flue gas additionally inside the dual heating flues. The method advantageously also may include recirculating externally at a predetermined flow rate the one portion of the flue gas considering the recirculating of the other portion of the flue gas inside the dual heating flues and controlling the recirculating so that a flame temperature in the heating flues is kept constant based on a heat balance in the heating flues, and feeding, during rich gas firing of the combination coke oven, the one portion of the flue gas recirculated externally only to those of the regenerators, which receive the underfiring media during lean gas operation, and, during rich gas operation, only to every second one of the regenerators.
In a method of reducing a nitrogen oxides content of a flue gas generated on firing of a rich gas or combination coke oven, said coke oven having a plurality of heating walls forming dual heating flues, in which a single stage or multistage combustion takes place, and said coke oven also having a plurality of regenerators for recovery of flue gas heat and preheating of an underfiring medium, the improvement comprising the steps of mixing one portion of said flue gas drawn from one flue of said dual heating flues with said underfiring medium not after admission to the other flue of said dual heating flues, recirculating another portion of said flue gas additionally inside said dual heating flues, recirculating externally at a predetermined flow rate said one portion of said flue gas and controlling said recirculating externally said one portion of said flue gas so that a flame temperature in said heating flues is kept constant based on a heat balance in said heating flues, and feeding, during rich gas firing of said coke oven, said one portion of said flue gas recirculated externally only to those of said regenerators, which receive said underfiring media during lean gas operation, and, during rich gas operation, only to every second one of said regenerators.
Dependencies are inferred from the claim text.