Gas purification

Claim 2

A process as claimed in claim 1 wherein an inert gas is introduced into the stripping zone to aid in volatilizing the hydrogen sulfide contained in the solvent.

Claim 3

A process as claimed in claim 3 wherein the stripping gas is purge gas from the methanol synthesis operation.

Claim 4

A process as claimed in claim 1 wherein the lean solvent is saturated with carbon dioxide in the conditioning zone.

Claim 5

A process as claimed in claim 1 wherein the gas mixture from the absorption zone undergoing expansion is used to drive an expansion turbine to generate power.

Claim 6

A process as claimed in claim 1 wherein the gas mixture entering the absorption zone is first passed in indirect heat exchange with the gases leaving the absorption zone to cool the gas mixture to a temperature below the temperature in the absorption zone prior to entering the absorption zone.

Claim 7

A process as claimed in claim 1 wherein the gas mixture to be purified in natural gas.

Claim 8

The process as claimed in claim 1 wherein the absorption zone is maintained at a pressure of 500-1,500 pounds per square inch absolute and the temperature is between 70* and 110* F.

Claim 9

A process as claimed in claim 1 wherein the solvent is a mixture of dimethyl ethers of polyethylene glycols having 3 -8 ethylene units.

Claim 10

A process for purification of natural gas containing principally methane together with carbon dioxide and minor amounts of hydrogen sulfide to remove substantially all the hydrogen sulfide while retaining most of the carbon dioxide in the gas mixture which comprises: a. maintaining an absorption zone under superatmospheric pressure within the range of about 500 to 1,500 pounds per square inch absolute, and a temperature between about 70* and 110* F.; b. passing the natural gas in indirect heat exchange with gas leaving the absorption zone to effect cooling of the natural gas entering the absorption zone to a temperature below the temperature in the absorption zone; c. introducing the cooled natural gas containing principally methane together with carbon dioxide and minor amouNts of hydrogen sulfide into the lower section of the absorption zone; d. introducing as a solvent medium, a mixture of dimethyl ethers of polyethylene glycols having 3 - 8 ethylene units saturated with carbon dioxide into the upper section of the absorption zone, said solvent medium having a temperature below the temperature in the absorption zone; e. passing the solvent medium downwardly countercurrent to and in intimate direct contact with the uprising gas mixture to remove substantially all the hydrogen sulfide together with a minor portion of carbon dioxide from the gas mixture; f. releasing the gas mixture containing the methane and carbon dioxide and substantially free of hydrogen sulfide from the absorption zone and passing said released gas mixture in indirect heat exchange with incoming natural gas feed; g. reducing the pressure on said gas mixture from the absorption zone to effect cooling and expansion of said gas mixture; h. passing said gas mixture into an expansion turbine to generate power; i. passing the cooled gas mixture in direct contact with lean solvent in a conditioning zone to cool the solvent to a temperature below the temperature of the absorption zone and to saturate the lean solvent with carbon dioxide; j. passing the cooled solvent containing dissolved carbon dioxide from the conditioning zone as solvent medium to the absorption zone for scrubbing the gas mixture containing hydrogen sulfide; k. discharging the gas mixture containing methane and carbon dioxide and substantially free of hydrogen sulfide from the conditioning zone; l. passing rich solvent containing hydrogen sulfide together with minor amounts of methane to a flashing zone to liberate minor amounts of methane dissolved in the rich solvent; m. passing the rich solvent containing hydrogen sulfide from the flashing zone to a stripping zone maintained at a pressure of 12 to 100 pounds per square inch absolute and at a temperature of 80* to 120* F. to volatilize the hydrogen sulfide contained in the solvent; n. discharging the hydrogen sulfide from the stripping zone; and o. passing the lean solvent from the stripping zone to the conditioning zone.

Claim 11

A process as claimed in claim 1 wherein the gas mixture to be purified is derived from fossil fuel.