Abstract: A method of purifying flue gas from the firing equipment of a combustion unit, especially fuel gas from fitting equipment to which low-ash flue is supplied, or from a grating firing having a high degree of ash removal, with the flue gas containing noxious compounds. A finely divided or pulverous basic additive is used on which the noxious compounds produced during firing are adsorbed. Flue dust, especially flue dust/additive mixture, that is carried along in the flue gas is separated from the latter, with at least a portion of the separated-off flue dust being hydrated and sifted, whereby subsequently at least a portion of the dry, hydrated flue dust is returned to the flue gas purification process. Non-pulverized flue dust is homogenously mixed with finely sprayed water to effect the hydration. The return of flue dust to the flue gas purification process is undertaken by returning at least a portion of dry, thus-hydrated flue dust to the firing equipment of the combustion unit.

Abstract: A method of continuously introducing additive, which is conveyed by gaseous and/or liquid carriers, into a turbulent reaction gas flow in the combustion chamber of a steam generator having dry ash withdrawal for selective removal, in a dry manner, of environmentally harmful gaseous noxious materials, such as sulfur, chlorine, and chlorine compounds, which are contained in a hot reaction gas flow which results after a complete or incomplete flame combustion of solid, liquid, or gaseous fuels. Depending upon the additive introduced, heat is stored and/or used for decomposition reactions. The additive, is first introduced at one or more input locations, due to locally different pressure conditions in the combustion chamber, into one or more recirculation flows which are within the system and are closed. The additive is subsequently withdrawn from these recirculation flows and is introduced into the reaction gas flow.