Coal gassification

Claim 2

A method according to claim 2 wherein all of said separated carbonaceous material is returned to said gasification vessel.

Claim 3

A method according to claim 2 wherein said gasification vessel has discrete operating stages, a first stage for forming a hot synthesis gas by reacting recycled carbonaceous material, oxygen, and steam and a second stage for reacting the carbonaceous fuel with the synthesis gas and steam, said recycled hydrogen and carbon monoxide injected into said second stage.

Claim 4

A method according to claim 2 wherein the effluent from the gasifier vessel is passed through a carbon monoxide, hydrogen shift reactor immediately after the solid carbonaceous material is separated from said stream.

Claim 5

In a process for producing a pipeline gas by reacting coal in the presence of steam and oxygen at elevated temperature and under super-atmospheric pressure in a two-stage gasifier to produce a gas mixture the improvement which comprises: combusting partially reacted carbon aceous material with oxygen in the presence of steam in a first stage of the gasifier at an elevated temperature, said temperature being selected to suppress the formation of methane in the first stage, and high pressure to form a hot synthesis gas; adding the synthesis gas to a mixture of finely divided coal and steam into the second stage of the gasifier to form a gasifier effluent consisting of solid carbonaceous particles suspended in a gas consisting of a mixture of methane, hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, and Water vapor; separating out the coal particles and returning a portion of said particles to the first stage of the gasifier as the source of partially reacted carbonaceous material; subjecting the gaseous remainder of the effluent to an acid gas removal process wherein carbon dioxide, hydrogen sulfide, and water vapor are removed and thereafter; liquefying said methane and separating said methane from said hydrogen and said carbon monoxide to produce a pipeline gas; warming said hydrogen and carbon monoxide mixture and injecting said mixture into the second stage of said gasifier; whereby the carbon monoxide-hydrogen recycle gas reacts exothermically with the coal in the gasifier to provide a portion of the heat required to sustain gasifier operation, heat balance between the stages is eliminated and the overall oxygen requirement is reduced thereby increasing the overall process efficiency.

Claim 6

A method according to claim 6 wherein all of said solid carbonaceous particles separated from said gasifier effluent is returned to the gasifier and reacted to form the hot synthesis gas.

Claim 7

A method according to claim 6 wherein the first stage of said gasifier is operated at a temperature in excess of 2600*F and at a pressure of greater than 70 atmosphere.

Claim 8

A method according to claim 6 wherein the second stage of said gasifier is operated at a minimum temperature of 1700*F and a pressure greater than 70 atmosphere.

Claim 9

A method according to claim 6 wherein the gaseous portion of the gasifier effluent is passed through a carbon monoxide hydrogen shift reactor prior to the acid gas removal step.