FORFARANDE OCH ANORDNING FOR KATALYTISK REDUKTION AV SKADLIGA EMNEN I ROKGASER

摘要

An apparatus and process for catalytically reducing noxious substances in flue gas wherein a heat exchanger is traversed from a top section to a bottom section by a plurality of heat storage elements which are separately movable and are charged by the flue gas transversely to their direction of movement. At least a portion of the heat storage elements are provided with a catalyst coating. Flue gas cooled downstream of a desulfurization system is conducted through the bottom section of the heat exchanger where it is preheated by the heat storage elements and is then heated to a predetermined reaction temperature by an external heating means. Ammonia is added and the flue gas is conducted at least once through at least one middle section of the heat exchanger for the catalytic reduction of the noxious substances. Then, the flue gas is conducted through the top section of the heat exchanger so as to cool it to a predetermined chimney entrance temperature. Not only is a decrease in catalytic activity prevented, but an adverse affect on the efficiency of the catalyst due to leakages from a gas preheater for the flue gas is prevented so that the heat exchanger can be used advantageously downstream of a desulfurization system.