Process for the selective removal of sulfur dioxide from effluent gases

Claim 1

The process for the selective removal of sulfur oxides from gas mixtures containing at least such sulfur oxides and carbon dioxide which comprises: (a) passing the gas mixture at a temperature below 80° C. through an absorber in countercurrent contact with an absorbent solvent composition consisting essentially of (1) from about 20 to about 60% by weight of monoethanolamine; (2) from about 10 to about 40% by weight of sulfur dioxide such that the molar ratio of sulfur dioxide to available monoethanolamine is always greater than or equal to 0.5/1; and (3) at least about 4% by weight water at a solvent composition flow to gas flow ratio such that the molar concentration of sulfur oxides to be absorbed therein does not exceed the molar concentration of water present; (b) absorbing said sulfur oxides in said solvent composition; (c) passing the aborbent solvent composition containing absorbed sulfur oxides at a maximum temperature of about 120° C., to at least one stripper tower and stripping the absorber sulfur dioxide from the absorbent solvent composition while maintaining the temperature in the stripper below 120° C.; (d) removing from the stripper a stripped lean solvent bottom composition containing a maximum of about 40% by weight of sulfur dioxide and at least about one mole of water for each mole of sulfur oxides remaining in said lead solvent; (e) recycling the stripped lean solvent bottoms from step (d) to the absorber together with sufficient water to provide a solvent absorbent composition having the same composition as defined in step (a); and (f) removing from the stripper a vapor consisting essentially of sulfur dioxide and water.