METHOD FOR CYCLIC REMOVAL OF SULFUR DIOXIDE FROM GAS FLOW Russian patent published in 1994 - IPC

FIELD: cleaning of exhaust gases of thermal power plants. SUBSTANCE: exhaust gases are in contact with absorbing medium of atmospheric pressure and temperature of 10 to 60 C. Absorbing medium contains less than 80 mas. % of water, preferably 25-50 mas. %, and water-soluble diamine semisalt. Absorbing medium is supplied, at least, 1 mole of water per each mole of sulfur dioxide. Diamine semisalt has pKa for free atom of nitrogen within 4.8-6.9. Molecular mass of respective diamine is less than 300. Preferably, used in absorbing medium is semisulfate or semisulfite of tertiary diamine of general formula given in invention description. Use may be also made of piperazine semisalt. Absorbing medium pH at inlet amounts to 6.5-7.5 and at outlet, at least 4. Spent absorbent is regenerated at 50-110 C with distillation of sulfur dioxide, at least, for 70 mol.%. Regeneration temperature, as minimum, is higher than the temperature of contacting stage by 30 C. Removed from regenerated absorbing medium are heat-resistant salts, and absorbing medium is recirculated to contacting stage. EFFECT: higher efficiency. 12 cl, 2 dwg, 3 tbl