Process for the dinitration of exhaust gas

摘要

A process is described in which a combustion gas from a combustion apparatus of a steam generator is subjected to a denitration treatment by a denitration apparatus followed by passing the resulting exhaust gas to a downstream dedusting apparatus, this process making it possible to prevent the catalyst in the denitration apparatus being poisoned by the heavy metal component which poisons the catalyst and which is contained in the fuel, without reducing the combustion efficiency. A secondary combustion furnace is created in order to burn unburnt materials which are contained in the ash, which contains a large amount of concentrated heavy metal elements as the component poisoning the catalyst, without returning the ash to the combustion apparatus of the steam generator. An ash heating apparatus can be provided in the middle of the ash circulation in order to remove the heavy metal elements, followed by return of the resulting exhaust gas upstream to an air heater for the steam generator (and downstream to the denitration apparatus), in order as a result to recover the heat of combustion of the unburnt material by the air heater.