Thermally enhanced compact reformer

• US 6,183,703 B1
• Filed: 01/11/1999
• Issued: 02/06/2001
• Est. Priority Date: 04/12/1996
• Status: Expired due to Term

• Current Assignee: ZTEK Corporation
• Original Assignee: ZTEK Corporation
• Inventors: Hoag, Ethan D., Hsu, Michael S.
• Primary Examiner(s): Beck, Shrive
• Assistant Examiner(s): NECKEL, ALEXA DOROSHENK
• Application Number:
  US09/459,403
• Time in Patent Office: 757 Days
• Field of Search: 422/211, 422/222, 422/198, 481/277, 481/279, 481/982, 481/988
• US Class Current: 422/211
• CPC Class Codes: B01D 53/864 Removing carbon monoxide or hydrocarbons
• CPC Class Codes: B01D 53/8653 characterised by a specific device
• CPC Class Codes: B01J 12/005 carried out at high temperatures, e.g. by pyrolysis
• CPC Class Codes: B01J 12/007 in the presence of catalytically active bodies, e.g. porous plates
• CPC Class Codes: B01J 15/005 in the presence of catalytically active bodies, e.g. porous plates
• CPC Class Codes: B01J 19/249 Plate-type reactors
• CPC Class Codes: B01J 2208/00309 with two or more reactions in heat exchange with each other, such as an endothermic reaction in heat exchange with an exothermic reaction
• CPC Class Codes: B01J 2208/022 Plate-type reactors filled with granular catalyst
• CPC Class Codes: B01J 2219/2453 Plates arranged in parallel
• CPC Class Codes: B01J 2219/2458 Flat plates, i.e. plates which are not corrugated or otherwise structured, e.g. plates with cylindrical shape
• CPC Class Codes: B01J 2219/2465 Two reactions in indirect heat exchange with each other
• CPC Class Codes: B01J 2219/2467 Additional heat exchange means, e.g. electric resistance heaters, coils
• CPC Class Codes: B01J 2219/2477 of the catalysts
• CPC Class Codes: B01J 2219/2479 Catalysts coated on the surface of plates or inserts
• CPC Class Codes: B01J 2219/2482 Catalytically active foils; Plates having catalytically activity on their own
• CPC Class Codes: B01J 2219/2485 Metals or alloys
• CPC Class Codes: B01J 2219/2487 Ceramics
• CPC Class Codes: B01J 2219/2493 Means for assembling plates together, e.g. sealing means, screws, bolts
• CPC Class Codes: B01J 2219/2498 Additional structures inserted in the channels, e.g. plates, catalyst holding meshes
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: C01B 2203/0233 : the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/0238 : the reforming step being a carbon dioxide reforming step
• CPC Class Codes: C01B 2203/0244 : the reforming step being an autothermal reforming step, e.g. secondary reforming processes
• CPC Class Codes: C01B 2203/0261 : containing a catalytic partial oxidation step [CPO]
• CPC Class Codes: C01B 2203/0283 : containing a CO-shift step, i.e. a water gas shift step
• CPC Class Codes: C01B 2203/066 : with fuel cells
• CPC Class Codes: C01B 2203/0811 : by combustion of fuel
• CPC Class Codes: C01B 2203/0833 : Heating by indirect heat exchange with hot fluids, other than combustion gases, product gases or non-combustive exothermic reaction product gases
• CPC Class Codes: C01B 2203/0838 : by heat exchange with exothermic reactions, other than by combustion of fuel
• CPC Class Codes: C01B 2203/0844 : the non-combustive exothermic reaction being another reforming reaction as defined in groups C01B2203/02 - C01B2203/0294
• CPC Class Codes: C01B 2203/0866 : by combination of different heating methods
• CPC Class Codes: C01B 2203/1035 : Catalyst coated on equipment surfaces, e.g. reactor walls
• CPC Class Codes: C01B 2203/1041 : Composition of the catalyst
• CPC Class Codes: C01B 2203/1205 : Composition of the feed
• CPC Class Codes: C01B 2203/1241 : Natural gas or methane
• CPC Class Codes: C01B 2203/1276 : Mixing of different feed components
• CPC Class Codes: C01B 2203/142 : At least two reforming, decomposition or partial oxidation steps in series
• CPC Class Codes: C01B 2203/80 : Aspect of integrated processes for the production of hydrogen or synthesis gas not covered by groups C01B2203/02 - C01B2203/1695
• CPC Class Codes: C01B 2203/82 : Several process steps of C01B2203/02 - C01B2203/08 integrated into a single apparatus
• CPC Class Codes: C01B 3/382 : Multi-step processes
• CPC Class Codes: C01B 3/384 : the catalyst being continuously externally heated
• CPC Class Codes: C01B 3/386 : Catalytic partial combustion
• CPC Class Codes: H01M 2008/1293 : Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 2300/0077 : based on zirconium oxide
• CPC Class Codes: H01M 8/04022 : Heating by combustion
• CPC Class Codes: H01M 8/0612 : from carbon-containing material
• CPC Class Codes: H01M 8/0618 : Reforming processes, e.g. autothermal, partial oxidation or steam reforming
• CPC Class Codes: H01M 8/0625 : in a modular combined reactor/fuel cell structure
• CPC Class Codes: H01M 8/0631 : Reactor construction specially adapted for combination reactor/fuel cell hydrogen C01B3/00; reactors for physicochemical processes B01J19/00
• CPC Class Codes: H01M 8/0662 : Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: H01M 8/2404 : Processes or apparatus for grouping fuel cells
• CPC Class Codes: H01M 8/2432 : Grouping of unit cells of planar configuration
• CPC Class Codes: H01M 8/2483 : characterised by internal manifolds
• CPC Class Codes: H01M 8/2484 : characterised by external manifolds
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/52 : using catalysts, e.g. selective catalysts

Abstract

A natural gas reformer comprising a stack of thermally conducting plates interspersed with catalyst plates and provided with internal or external manifolds for reactants. The catalyst plate is in intimate thermal contact with the conducting plates so that its temperature closely tracks the temperature of the thermally conducting plate, which can be designed to attain a near isothermal state in-plane to the plate. One or more catalysts may be used, distributed along the flow direction, in-plane to the thermally conducting plate, in a variety of optional embodiments. The reformer may be operated as a steam reformer or as a partial oxidation reformer. When operated as a steam reformer, thermal energy for the (endothermic) steam reforming reaction is provided externally by radiation and/or conduction to the thermally conducting plates. This produces carbon monoxide, hydrogen, steam and carbon dioxide. When operated as a partial oxidation reformer, a fraction of the natural gas is oxidized assisted by the presence of a combustion catalyst and reforming catalyst. This produces carbon monoxide, hydrogen, steam and carbon dioxide. Because of the intimate thermal contact between the catalyst plate and the conducting plates, no excessive temperature can develop within the stack assembly. Details of the plate design may be varied to accommodate a variety of manifolding embodiments providing one or more inlets and exit ports for introducing, pre-heating and exhaust the reactants.

Claims

1. A method for reforming a reactant into reaction species with a plate-type reformer, comprising the steps of

providing a plurality of catalyst plates having associated therewith one or more catalyst materials for promoting reformation,

providing a plurality of conductive plates formed of a thermally conducting material,

stacking said catalyst plates and said conductive plates to form a plate-type reforming structure,

conductively transferring heat energy in-plane across a surface of the conductive plate to support the reforming process, and

reforming the reactant into the reaction species when passing through the platetype reforming structure.

2. The method of claim 1, further comprising the step of performing one or more reforming reactions including a catalytically assisted chemical reaction between two or more reaction species, and a catalytically assisted thermal dissociation of a single species.

3. The method of claim 1, further comprising the steps of introducing the reactant through at least one axial manifold in said reforming structure, and forming at least one manifold in said reforming structure for allowing the reaction species to exit from the reforming structure.

4. The method of claim 1, further comprising the step of exposing a substantial portion of the peripheral surface of the reforming structure to allow the exchange of heat energy with an external environment.

5. The method of claim 1, further comprising the steps of forming one or more axial reactant manifolds in said reforming structure for introducing the reactant thereto, and exhausting reaction species from a peripheral portion of the reforming structure.

6. The method of claim 1, further comprising the steps of disposing a thermally conductive, gas-tight housing about the reforming structure to form a peripheral axial manifold to allow pressurized reformer operation, introducing reaction species into the peripheral axial manifold, and capturing said reaction species with said gas-tight housing.

7. The method of claim 1, further comprising the steps of disposing a thermally conductive, gas-tight housing about said reforming structure, and exchanging heat energy between the external environment and said conductive plate by one of radiation, conduction and convection.

8. The method of claim 1, further comprising the steps of

disposing a thermally conductive, gas-tight housing about said reforming structure,

placing in contact an outer surface of the reforming structure with an inner surface of said gas-tight housing, and

conductively transferring heat energy from said gas-tight housing to the conductive plates.

9. The method of claim 1, further comprising the step of forming a generally isothermal condition, in plane of the conductive plate.

10. The method of claim 1, further comprising the step of forming a generally isothermal condition along an elongated axis of the reforming structure.

11. The method of claim 1, further comprising the steps of

forming at least one axial reactant manifold in said reforming structure for introducing a reactant thereto,

providing an integrally formed lip structure on an outer end or an inner end of the conductive plate, and

preheating an incoming reactant with said lip structure when extending into the axial reactant manifold.

12. The method of claim 1, further comprising the step of forming a passage in an in-plane surface of at least one of the conductive plate and the catalyst plate for allowing the reactant to flow over the surface of the plate.

13. The method of claim 1, further comprising the steps of

forming an axial manifold within the reforming structure,

forming passages between the conductive plate and the catalyst plate, and

generating a reactant flow pressure drop through the passages between the conductive plate and the catalyst plate that is substantially greater than a reactant flow pressure drop within the axial manifold.

14. The method of claim 1, further comprising the steps of

forming passages between the catalyst plate and the conductive plate for allowing an incoming reactant to pass over a surface of one of the plates, and

maintaining a substantially uniform pressure drop within the reforming structure to provide for a substantially uniform flow of reactants along an axis of the reforming structure.

15. The method of claim 1, further comprising the step of producing a substantially uniform temperature condition along an axis of the reforming structure.

16. The method of claim 1, further comprising the step of forming the catalyst plate and of a porous catalyst material or the conductive plate of a porous conductive material to form passages therein to allow an incoming reactant to pass through at least a portion of the plate.

17. The method of claim 1, further comprising the step of forming the conductive plate of at least one of a nonmetal such as silicon carbide, and a composite material.

18. The method of claim 1, further comprising the step of forming the conductive plate of at least one metal such as aluminum, copper, iron, steel alloys, nickel, nickel alloys, chromium, chromium alloys, platinum, platinum alloys and other refractory metals.

19. The method of claim 1, further comprising the step of forming the catalyst plate of a ceramic or metallic support plate having the catalyst material coating.

20. The method of claim 1, further comprising the step of selecting the catalyst material from the group consisting of platinum, palladium, nickel, nickel oxide, iron, iron oxide, chromium, chromium oxide, cobalt, cobalt oxide, copper, copper oxide, zinc, zinc oxide, molybdenum, molybdenum oxide, and other suitable transition metals and their oxides.

21. The method of claim 1, further comprising the step of forming the catalyst plate of at least one of platinum, nickel, nickel oxide, chromium and chromium oxide.

22. The method of claim 1, further comprising the step of forming the reactant from at least one of an alkane such as a paraffin hydrocarbon, a hydroxyl such as a hydrocarbon bonded with alcohols, a hydrocarbon bonded with a carboxyl, a hydrocarbon bonded with a carbonyl, an alkene such as an olifin hydrocarbon, a hydrocarbon bonded with an ether, a hydrocarbon bonded with an ester, a hydrocarbon bonded with an amine, a hydrocarbon bonded with an aromatic derivative, and a hydrocarbon bonded with another organo-derivative.

23. The method of claim 1, further comprising the step of coupling reaction species exiting the reforming structure to an external fuel cell.

24. The method of claim 1, further comprising the steps of providing a hydrocarbon fuel as a fuel reactant and at least one of H₂O and CO₂, and performing on the hydrocarbon fuel and at least said one of H₂O and CO₂ an endothermic catalytic reformation to produce H₂, CO, H₂O and CO₂, the energy requirements for the endothermic reforming being supplied by energy produced by an external fuel cell, said energy being transferred from the fuel cell by the conducting plate through in-plane thermal conduction.

25. The method of claim 1, further comprising the steps of providing a hydrocarbon fuel as a fuel reactant and at least one of H₂O and CO₂, and performing on the hydrocarbon fuel and O₂ a catalytic combustion and reformation processes to produce H₂, CO, H₂O and CO₂, and at least one of an exothermic combustion and an exothermic reaction of an external fuel cell supplementing the energy requirements for the endothermic reforming through the in-plane thermal conduction of the conducting plate.

26. The method of claim 1, further comprising the steps of forming the reforming structure in a cylindrical shape, and providing at least one of the catalyst plate and the conductive plate of a diameter between about 1 inch and about 20 inches, and a thickness between about 0.002 inch and about 0.2 inch.

27. The method of claim 1, further comprising the step of only conducting heat with said conductive plates in the in-plane direction from one end region of the surface to another.

28. The method of claim 1, further comprising the step of forming the catalyst plate to have a plurality of zones spaced along a surface of the plate for effecting selected reactions, said zones including a combustion zone, a reforming zone, and an electrochemical zone.

29. The method of claim 1, further comprising the step of forming with said conductive plate a near isothermal temperature condition in-pane of said catalyst and said conductive plates.

30. The method of claim 1, further comprising the steps of

configuring said reforming structure to extend, in one orientation, along a vertical axis, and

configuring said reforming structure to include at least one vertically-extending axial manifold for introducing the reactant thereto and at least one manifold for allowing the reaction species to exit from the reforming structure.

31. The method of claim 1, further comprising the steps of

exhausting the reaction species from a peripheral portion of the reforming structure, and

disposing a thermally conductive, gas-tight housing about the stacked reforming structure to capture the reaction species exhausted by said reforming structure through said peripheral portion.

32. The method of claim 31, further comprising the steps of allowing the reaction species to enter the gas-tight housing, and capturing the reaction species with the gas-tight housing.

33. A method for reforming a reactant into reaction species with a plate-type reformer during operation, said method comprising the steps of

providing a plurality of plates at least one of said plurality of said plates being composed of a thermally conductive material interspersed throughout a thickness of the plate with one or more catalyst materials for promoting the reforming process,

stacking said plates being together to form a reforming structure,

conductively transferring heat energy in-plane, across a surface of the plates, to support the reforming process, and

reforming the reactant into the reaction species when passing through the reforming structure.

34. The method of claim 33, further comprising the steps of

introducing the reactant through at least one axial manifold formed in said reforming structure, and

forming at least one manifold in said reforming structure for allowing the reaction species to exit from the reforming structure.

35. The method of claim 33, further comprising the step of exposing a substantial portion of a peripheral surface of the reforming structure to allow the exchange of heat energy with an external environment.

36. The method of claim 33, further comprising the steps of

forming one or more axial reactant manifolds in said reforming structure for introducing the reactant thereto, and

exhausting reaction species from a peripheral portion of the reforming structure.

37. The method of claim 33, further comprising the steps of

disposing a thermally conductive, gas-tight housing about the reforming structure to form a peripheral axial manifold to allow pressurized reformer operation,

introducing reaction species into the peripheral axial manifold, and

capturing said reaction species with said gas-tight housing.

38. The method of claim 33, further comprising the steps of

disposing a thermally conductive, gas-tight housing about said reforming structure, and

exchanging heat energy between the external environment and said reforming structure by one of radiation, conduction and convection.

39. The method of claim 33, further comprising the steps of

disposing a thermally conductive, gas-tight housing about said reforming structure,

placing in contact an outer surface of the reforming structure with an inner surface of said gas-tight housing, and conductively transferring heat energy from said gas-tight housing to the reforming structure.

40. The method of claim 33, further comprising the step of forming a generally isothermal condition, in plane of the conductive plate, or along an elongated axis of the reforming structure.

41. The method of claim 33, further comprising the steps of

forming at least one axial reactant manifold in said reforming structure for introducing a reactant thereto,

providing an extension on an outer end or an inner end of the conductive plate, and

preheating an incoming reactant with said extension when extending into the axial reactant manifold.

42. The method of claim 33, further comprising the step of forming a passage in said reforming structure for allowing the reactant to flow over the surface of one of said plates.

43. The method of claim 33, further comprising the steps of

forming an axial manifold within the reforming structure,

forming passages in said reforming structure for allowing a reactant to flow inplane of the reforming structure, and

generating a reactant flow pressure drop through the passages that is substantially greater than a reactant flow pressure drop within the axial manifold.

44. The method of claim 43, further comprising the step of allowing the hydrocarbon fuel and at least one of H₂O and CO₂ to undergo a catalytic reformation to produce H₂, CO, H₂O and CO₂, and wherein an exothermic reaction of an external fuel cell supplements the energy requirements for the endothermic reforming reaction of the reforming structure through the thermally conductive material.

45. The method of claim 43, further comprising the step of allowing the hydrocarbon fuel and O₂ to undergo catalytic combustion and reformation to produce H₂, CO, H₂O and CO₂, and at least one of an exothermic combustion and an exothermic reaction of an external fuel cell supplements the energy requirements for the endothermic reforming reaction of the reforming structure through the thermally conductive material.

46. The method of claim 33, further comprising the steps of

forming passages between the catalyst plate and the conductive plate for allowing an incoming reactant to pass over a surface of one of the plates, and

maintaining a substantially uniform pressure drop within the reforming structure with said passages to provide for a substantially uniform flow of reactants along an axis of the reforming structure.

47. The method of claim 33, further comprising the step of forming the conductive plate of at least one of a nonmetal such as silicon carbide, and a composite material.

48. The method of claim 33, further comprising the step of forming the conductive plate of at least one metal such as aluminum, copper, iron, steel alloys, nickel, nickel alloys, chromium, chromium alloys, platinum, and platinum alloys.

49. The method of claim 33, further comprising the step of selecting the catalyst material from the group consisting of platinum, palladium, nickel, nickel oxide, iron, iron oxide, chromium, chromium oxide, cobalt, cobalt oxide, copper, copper oxide, zinc, zinc oxide, molybdenum, molybdenum oxide, and other suitable transition metals and their oxides.

50. The method of claim 33, further comprising the step of selecting the catalyst a material from a group consisting of platinum, palladium, nickel, nickel oxide, iron, iron oxide, chromium, chromium oxide, cobalt, cobalt oxide, copper, copper oxide, zinc, zinc oxide, molybdenum, molybdenum oxide, other transition metals and their oxides.

51. The method of claim 33, further comprising the step of providing as the reactant a hydrocarbon species and at least one of O₂, H₂O and CO₂.

52. The method of claim 33, further comprising the step of coupling the reaction species exiting the reformer to an external fuel cell.

53. The method of claim 33, further comprising the step of configuring the reforming structure to have a cylindrical shape and a diameter between about 1 inch and about 20 inches.

54. The method of claim 33, further comprising the step of only conducting heat with said conductive plates in the in-plane direction from one end region of the surface to another.

55. The method of claim 33, further comprising the step of forming with said conductive plate a near isothermal temperature condition in-pane of said catalyst and said conductive plates.

56. A method for reforming a reactant into reaction species, comprising the steps of providing a plurality of catalyst plates having one or more zones spaced along a surface of at least one of said plurality of catalyst plates for effecting selected reactions, said zones including at least one of a combustion zone, a reforming zone, and an electrochemical zone,

providing a plurality of conductive plates formed of a thermally conducting material,

stacking said catalyst plates and said conductive plates to form a plate-type reforming structure,

conductively transferring heat energy in-plane across a surface of the conductive plate to support the reforming process, and

reforming the reactant into the reaction species when passing through the plate-type returning structure.

57. The method of claim 56, further comprising the steps of

providing steam as part of the reactant,

providing a steam reforming catalyst in said reforming zone, and

providing heat for the reforming zone to support the reformation process by the conductively transferred heat energy flowing in-plane across the surface of the conductive plate.

58. The method of claim 56, further comprising the step of forming said zones into bands that are spaced from each other across the surface of the plate.

59. The method of claim 56, further comprising the step of

configuring the catalyst plate into a cylindrical shape,

disposing the combustion zone at an outermost region of the cylindrical plate relative to the fuel flow,

disposing the reforming zone at an intermediate region of the cylindrical plate relative to the fuel flow, and

disposing the electrochemical zone at an innermost region of the plate relative to the fuel flow.

60. The method of claim 56, further comprising the steps of

first passing a fuel reactant over the combustion zone,

then passing the reactant over the reforming zone, and

finally passing the reactant over the electrochemical zone.

61. The method of claim 56, further comprising the steps of

providing oxygen as part of the reactant,

providing a combustion catalyst in said combustion zone,

providing a steam reforming catalyst in said reforming zone, and

providing heat for the reforming zone to support the reformation process from the combustion zone to the reformation zone by the conductive transfer of heat energy flowing in-plane across the surface of the conductive plate.

62. The method of claim 56, further comprising the step of exposing a substantial portion of the peripheral surface of the reforming structure to allow the exchange of heat energy with an external environment.

63. The method of claim 56, further comprising the steps of

forming one or more axial reactant manifolds in said reforming structure for introducing the reactant thereto, and

exhausting reaction species from a peripheral portion of the reforming structure.

64. The method of claim 56, further comprising the steps of

disposing a thermally conductive, gas-tight housing about the reforming structure to form a peripheral axial manifold to allow pressurized reformer operation,

introducing reaction species into the peripheral axial manifold, and

capturing said reaction species with said gas-tight housing.

65. The method of claim 56, further comprising the step of forming a generally isothermal condition, in plane of the reforming structure with said conductive plate during use.

66. The method of claim 56, further comprising the step of forming a generally isothermal condition along an elongated axis of the reforming structure with said conductive plate during use.

67. The method of claim 56, further comprising the steps of

forming at least one axial reactant manifold in said reforming structure for introducing a reactant thereto,

providing an integrally formed lip structure on an outer end or an inner end of the conductive plate, and

preheating an incoming reactant with said lip structure when extending into the axial reactant manifold.

68. A method for reforming a reactant into reaction species, comprising the steps of

providing a plate-type reformer having stacked catalyst and conductive plates,

conductively transferring heat energy in-plane across a surface of the conductive plate to support the reforming process, and

reforming the reactants into the reaction species when passing through the platetype reformer.