METHOD AND SYSTEM FOR THE DENITRIFICATION OF FLUE GASES BY MEANS OF SNCR (SELECTIVE NON-CATALYTIC REDUCTION) AND DOWNSTREAM CATALYST FOR AMMONIA DECOMPOSITION

摘要

The invention relates to a method for the denitrification of flue gases (1) and to a corresponding system, wherein the flue gases (1), which are generated in a rotary kiln (2) for sintering cement clinker, are conveyed to a calcining zone (3) for the deacidification of raw cement meal. Aqueous ammonia solution, ammonia (NH3), or ammonia-releasing substances (6) for denitrifying the flue gases (1) are injected into the calcining zone (3) according to the method of selective non-catalytic reduction (SNCR), and the flue gas stream, together with an ammonia slip (6) generated during the denitrification, is passed through a heat exchanger (9) and through at least one dedusting device (10). According to the invention, the flue gas stream is guided from the heat exchanger (9) through a heat exchanger exhaust gas line (11) via a catalyst (12) for the decomposition of excess ammonia (6) with residues of nitrogen oxide contained in the flue gas (1) in accordance with a method of selective catalytic reduction (SCR), wherein the catalyst (12) is arranged in a reactor (13) provided in the heat exchanger exhaust gas line (11), and is no larger than is required for a sufficient decomposition of the ammonia (6). The advantage of this is that relatively small catalysts (12) can be used.