Abstract: The flue gases from a wet-operating flue gas desulfurization plant contain liquid droplets loaded with solid material. These can lead to incrustations which are hard to remove and to corrosion. Previously, in order to dry the droplets, the flow of flue gases was heated by unpurified crude gas, steam or hot water or indirectly by hot air. In order to use less energy in drying the droplets, it is now proposed that the drying energy for evaporating the liquid from the droplets is supplied to the gas flow in a channel by radiant energy from a radiator. The gas flow is only heated to such a degree that the water vapour and carbon dioxide contained in the gas flow selectively absorb radiation of certain wavelengths, while the liquid droplets directly absorb the necessary heat for evaporation. It is also possible for the radiant energy to be absorbed by an assembly which can be heated by radiation and which then releases energy into the gas flow.