Process for removing dust and fly ash as well as sulphur oxides and nitrogen oxides from flue gases

摘要

To remove dust and fly ash as well as sulphur oxides and nitrogen oxides from flue gases, the flue gases are conditioned and passed through a plurality of moving beds of granular carbon-containing sorbents. For improved utilisation of the sorbents, dust and fly ash are removed from the flue gases by a first moving bed, the first moving bed being composed of sorbents which have been taken off from a second moving bed. Sulphur oxides are only removed from the flue gases freed from dust and fly ash by a second moving bed. The second moving bed is formed from sorbents which have been taken off from a third moving bed. By means of the third moving bed, nitrogen oxides and further sulphur oxides are removed from the flue gases which are substantially freed from sulphur oxides and to which has been added a mixture of gaseous ammonia, pure gas and air. The process according to the invention, as a result of the conditioning of the flue gases, leads to an increase in the service life of the sorbents by 100% or more, an increase in the loading of the sorbents by 90% or more and to a diminution of the plant required for carrying out the process. By the use of preloaded sorbents for dedusting, this can also be carried out particularly economically, especially since multiple use of the sorbents results in a significant reduction in operating costs.