Process for removal of contaminants from a gas stream

This invention relates to the treatment of gas streams, and in particular to an improved method for solvent extraction of hydrogen sulfide and other contaminants from sour gas feed stocks, tail gases, ammonia, and flue gas streams. A selected contaminant is removed from a gas stream containing an unselected component that is also absorbed by the solvent, although to a lesser degree than the selected contaminant. In a typical application, hydrogen sulfide is removed from a natural gas stream that contains carbon dioxide as an unselected component. The process employs a solvent absorption/regeneration sequence, carried out in an absorber and regenerator, to remove the selected contaminant (hydrogen sulfide, for example) from the gas stream. The overhead gas from the regenerator has a higher concentration of the selected contaminant than the original gas stream. This contaminant rich overhead gas stream is partially employed as a recycle stream that is combined with the original gas stream, with the resulting combined gas stream being fed to the absorber. The increased partial pressure of the selected contaminant in the absorber shifts the operating point, resulting in increased absorption of the selected contaminant relative to the unselected component. The regenerator overhead gas has a relatively high concentration of the selected contaminant.