Systems and methods for gasifying a hydrocarbon feedstock

1. A method for gasifying a hydrocarbon feedstock, comprising:

gasifying a hydrocarbon feedstock in a gasifier in the presence of one or more particulates to produce a syngas and carbon-containing particulates;

recycling the produced syngas using processes external to the gasifying of the hydrocarbon feedstock, wherein the processes external to the gasifying of the hydrocarbon feedstock sequentially comprise:

cooling the syngas by at least a first heat exchanger,

performing particulate control on the cooled syngas,

further cooling the cooled syngas after the particulate control by at least a second heat exchanger,

heating the twice cooled syngas in a combustor external to the gasifier, and

introducing the heated syngas to the gasifier;

cooling the carbon-containing particulates;

combusting at least a portion of the carbon of the cooled carbon-containing particulates in a combustion process by the combustor external to the gasifying of the hydrocarbon feedstock to produce a combustion gas; and

utilizing the combustion gas in further processes external to the gasifying of the hydrocarbon feedstock,

wherein the further processes external to the gasifying of the hydrocarbon comprise drying a moisture-containing hydrocarbon feedstock to produce a dried hydrocarbon feedstock, and

wherein the hydrocarbon feedstock comprises the dried hydrocarbon feedstock.

2. The method of claim 1 , wherein the carbon-containing particulates comprise carbon-containing coarse ash, carbon-containing fine ash, or a combination thereof.

3. The method of claim 1 , wherein the processes external to the gasifying of the hydrocarbon feedstock further comprise: heating a boiler feed water; heating at least a portion of the syngas; heating a first oxidant; heating a steam; or a combination thereof.

4. The method of claim 3 , wherein heating the boiler feed water produces a first steam, and wherein the method further comprises introducing the first steam to the gasifying of the hydrocarbon feedstock, exporting the first steam to a process external to the gasifying of the hydrocarbon feedstock, supplying the first steam to a steam turbine to produce electrical power, or a combination thereof.

5. The method of claim 3 , wherein heating the first oxidant produces a heated first oxidant, and wherein the method further comprises introducing the heated first oxidant to the gasifying of the hydrocarbon feedstock.

6. The method of claim 3 , wherein heating the steam produces a second steam, and wherein the method further comprises introducing the second steam to the gasifying of the hydrocarbon feedstock, exporting the second steam to a process external to the gasifying of the hydrocarbon feedstock, supplying the second steam to a steam turbine to produce electrical power, or a combination thereof.

7. The method of claim 1 , wherein the dried hydrocarbon feedstock has a moisture concentration ranging from about 12 wt % to about 22 wt %.

8. The method of claim 1 , wherein the particulates comprise sand, ceramic materials, ash, crushed limestone, inorganic oxides, or a combination thereof.

9. The method of claim 1 , wherein the combustor comprises one of: a slagging combustor, an ash furnace, and a pulverized-coal furnace; and the combustion process further comprising:

maintaining a molar ratio of oxygen in a sub-stoichiometric proportion during the gasifying process; and

maintaining a stoichiometric excess of combustion oxidant during the combustion process.

10. The method of claim 1 , wherein the hydrocarbon feedstock comprises one or more bituminous coals, one or more sub-bituminous coals, one or more anthracite coals, one or more petroleum cokes, or a combination thereof.

11. The method of claim 1 , wherein the gasifier is selected from one of: (i) a circulating solids gasifier, and (ii) an entrained flow gasifier.

12. The method of claim 1 , further comprising

conveying the syngas from the gasifier using a first line;

conveying at least a portion of the one or more carbon-containing particulates from the gasifier using a second line separate from the first line; and

conveying the at least a portion of the carbon-containing particulates using the second line to the hydrocarbon stock being gasified.

13. The method of claim 12 , further comprising separating the syngas from the carbon-containing particulates, wherein the separated carbon containing particulates is conveyed by the second line.

14. The method of claim 12 , wherein the coarse ash is conveyed via the second line, and the fine ash is conveyed to the hydrocarbon stock being gasified using a third line separate from the second line.

15. A method for gasifying a hydrocarbon feedstock, comprising:

gasifying a hydrocarbon feedstock in a gasifier in the presence of one or more particulates to produce a syngas and carbon-containing particulates;

recycling the produced syngas using processes external to the gasifying of the hydrocarbon feedstock, wherein the processes external to the gasifying of the hydrocarbon feedstock sequentially comprise:

cooling the syngas by at least a first heat exchanger;

performing particulate control on the cooled syngas;

further cooling the cooled syngas after the particulate control by at least a second heat exchanger;

heating the twice cooled syngas in a combustor external to the gasifier; and

introducing the heated syngas to the gasifier;

combusting at least a portion of the carbon of the carbon-containing particulates in a combustion process by the combustor external to the gasifying of the hydrocarbon feedstock to produce a combustion gas; and

utilizing the combustion gas in further processes external to the gasifying of the hydrocarbon feedstock,

wherein the further processes external to the gasifying of the hydrocarbon feedstock comprise drying a moisture-containing hydrocarbon feedstock to produce a dried hydrocarbon feedstock,

wherein the hydrocarbon feedstock comprises the dried hydrocarbon feedstock,

wherein the one or more carbon-containing particulates comprise carbon-containing coarse ash, carbon-containing fine ash, or a combination thereof, and

wherein the one or more processes external to the gasifying of the hydrocarbon feedstock comprise: heating a boiler feed water; heating a first oxidant; heating a steam; or a combination thereof.

16. The method of claim 15 , wherein heating the boiler feed water produces a first steam, heating at least a portion of the syngas produces a heated syngas, heating the first oxidant produces a heated first oxidant, heating the steam produces a second steam, and drying the moisture-containing hydrocarbon feedstock produces a dried hydrocarbon feedstock having a moisture concentration ranging from about 12 wt % to about 22 wt %, the method further comprising:

introducing the first steam to the gasifying of the hydrocarbon feedstock, exporting the first steam to a process external to the gasifying of the hydrocarbon feedstock, supplying the first steam to a steam turbine to produce electrical power, or a combination thereof;

introducing the heated syngas to the gasifying of the hydrocarbon feedstock;

introducing the heated first oxidant to the gasifying of the hydrocarbon feedstock;

introducing the second steam to the gasifying of the hydrocarbon feedstock, exporting the second steam to a process external to the gasifying of the hydrocarbon feedstock, supplying the second steam to a steam turbine to produce electrical power, or a combination thereof; and

introducing the dried hydrocarbon feedstock to the gasifying of the hydrocarbon feedstock.

17. The method of claim 15 , wherein the at least a portion of the carbon of the carbon-containing particulates is combusted in the combustor, wherein the combustor comprises one of: a slagging combustor, an ash furnace, and a pulverized-coal furnace.

18. The method of claim 15 , further comprising:

cooling the carbon-containing particulates before combusting the at least a portion of the carbon of the carbon-containing particulates; and

using a supplemental fuel in addition to the at least a portion of the carbon of the carbon-containing particulates during the combustion.