At least one absorbent is added to the exhaust gas, which is passed at temperatures in the range from about 40.degree. to 500.degree. through a fluidized bed reactor and through dedusting means. Part of the solids separated in the dedusting means is recycled to the fluidized bed reactor. At least part of the recycled solids is blown with an entraining gas upwardly through a tube into the lower portion of the reactor. At least part of the combustion exhaust gas is fed to the reactor as a rising stream from a space which surrounds the tube. Air or combustion exhaust gas may be used, e.g., as an entraining gas.