Method of reducing nitrogen oxides from coke-oven flue gas
The invention relates to a method for reducing nitrogen oxides from the exhaust gas of a coke oven, which has a plurality of coking chambers and heating walls, arranged between the coking chambers, with heating flues (12, 12′) for the indirect heating of the coking chambers. A combustible gas (16), which consists entirely or partially of coke oven gas, is burned in the heating flues (12, 12′), thereby producing an exhaust gas which contains nitrogen oxides. A reducing agent is fed to the exhaust gas at a temperature between 700° C. and 1100° C. and the proportion of nitrogen oxide in the exhaust gas is reduced by a homogeneous gas reaction between the reducing agent and the nitrogen oxides. The exhaust gas is subsequently passed through a regenerator (4) for heat recovery. Furthermore, carbon deposits on hot parts of the combustible gas feed are burned with decarbonizing air, wherein, during a regenerator half-period in which the combustible gas feed to one heating flue (12′) is stopped, the decarbonizing air is introduced into this heating flue (12′) through the associated burner supply line and combustible gas nozzle (15′) and is discharged from another heating flue (12) with the hot exhaust gas. According to the invention, metered amounts of the reducing agent are fed into the decarbonizing air and, together with it, brought into contact with the hot exhaust gas.