Acid gas removal from gas mixtures

Claim 1

A process for removing hydrogen sulfide from a natural gas mixture containing methane, carbon dioxide, and hydrogen sulfide which comprises the steps of: a. contacting said gaseous mixture in a first absorption zone under superatmospheric pressure with a solvent comprising a mixture of dimethyl ethers of polyethylene glycols having dissolved therein at least 1 weight percent carbon dioxide to effect absorption of most of the hydrogen sulfide, carbon dioxide and a minor portion of the methane so as to partially purify the gas; b. contacting said partially purified gas from the first absorption zone in a second absorption zone under superatmospheric pressure with a solvent comprising a mixture of dimethyl ethers of polyethylene glycols essentially free of hydrogen sulfide and containing less than 1 weight percent carbon dioxide, to produce a purified gas containing no more than 10 p.p.m. hydrogen sulfide by volume and less than 5 percent carbon dioxide by volume; c. passing the solvent containing dissolved Gases from the second absorption zone to the first absorption zone; d. passing the solvent containing dissolved hydrogen sulfide, carbon dioxide and methane from the first absorption zone to a flashing zone maintained at a pressure substantially lower than that in the first absorption zone to effect liberation of most of the carbon dioxide and methane therefrom; e. withdrawing from said flashing zone gases liberated therein; f. passing a major portion of solvent containing hydrogen sulfide and at least 1 weight percent carbon dioxide from said flashing zone to said first absorption zone; g. passing a minor portion of solvent containing hydrogen sulfide and at least 1 weight percent carbon dioxide from said flashing zone to a stripping zone maintained at a temperature of about 45*-210* F.; h. contacting said solvent in the stripping zone with an oxygen-containing gas to effect removal of substantially all of the hydrogen sulfide therefrom; and i. returning desorbed solvent to the second absorption zone for further contact with the gaseous mixture.