GB1323931A - Desulphurization of flue gas - Google Patents

Abstract

1323931 Desulphurizing flue gas; thiosulphates CONSOLIDATION COAL CO 30 July 1970 [24 Nov 1969] 36931/70 Addition to 1191427 Heading C1A Hot flue gas containing sulphur dioxide is contacted with ammonium, sodium or potassium formate in solution or in the molten form at a temperature above 140‹ F. and below the decomposition temperature of the formate producing the corresponding thiosulphates and reducing the sulphur dioxide content of the hot flue gas. The temperature may be below 475 degrees. The formate may be in aqueous solution and the corresponding carbonate may also be present. The product thiosulphate may be isolated as such, or used to regenerate formate for recycle to treat further flue gas. In an embodiment of the latter process gas containing sulphur dioxide is contacted with excess potassium formate (e.g. 85%), whereby less than 25% by wt. of formate is converted to thiosulphate, in a scrubber 10. The resulting thiosulphate is then converted to the corresponding carbonate with the excess formate in redactor vessel 20; the products from which are then stripped of H 2 S by means of CO 2 and steam in 26, and carbonate present is converted to formate in 34, the regenerated formate being returned to the scrubber 10.