High temperature fuel cell system and method of operating same

• US 7,422,810 B2
• Filed: 12/03/2004
• Issued: 09/09/2008
• Est. Priority Date: 01/22/2004
• Status: Active Grant

• Current Assignee: Bloom Energy Corporation
• Original Assignee: Bloom Energy Corporation
• Inventors: Gottmann, Matthias, Finn, John, Venkataraman, Swaminathan
• Primary Examiner(s): Crepeau; Jonathan
• Assistant Examiner(s): HODGE, ROBERT W
• Application Number:
  US11/002,681
• Publication Number:
  US 20050164051A1
• Time in Patent Office: 1,376 Days
• Field of Search: None
• US Class Current: 429/411
• 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 2208/00716 Means for reactor start-up
• CPC Class Codes: B01J 2219/00006 Large-scale industrial plants
• CPC Class Codes: B01J 2219/2465 Two reactions in indirect heat exchange with each other
• CPC Class Codes: B01J 2219/2479 Catalysts coated on the surface of plates or inserts
• CPC Class Codes: B01J 2219/2481 Catalysts in granular from between plates
• CPC Class Codes: B01J 8/0257 in a cylindrical annular shaped bed
• CPC Class Codes: B01J 8/0285 Heating or cooling the reactor for tubular reactors in furnaces B01J8/062
• CPC Class Codes: C01B 2203/0233 the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/0283 containing a CO-shift step, i.e. a water gas shift step
• CPC Class Codes: C01B 2203/043 Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/0495 the impurity being water
• CPC Class Codes: C01B 2203/066 with fuel cells
• CPC Class Codes: C01B 2203/0811 by combustion of fuel
• CPC Class Codes: C01B 2203/0822 the fuel containing hydrogen
• CPC Class Codes: C01B 2203/1035 Catalyst coated on equipment surfaces, e.g. reactor walls
• CPC Class Codes: C01B 2203/1241 Natural gas or methane
• CPC Class Codes: C01B 2203/127 Catalytic desulfurisation
• CPC Class Codes: C01B 2203/1294 : Evaporation by heat exchange with hot process stream
• CPC Class Codes: C01B 3/384 : the catalyst being continuously externally heated
• CPC Class Codes: C01B 3/48 : followed by reaction of water vapour with carbon monoxide
• CPC Class Codes: C01B 3/56 : by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• CPC Class Codes: H01M 2008/1293 : Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 8/04007 : related to heat exchange
• CPC Class Codes: H01M 8/04022 : Heating by combustion
• CPC Class Codes: H01M 8/04097 : with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04164 : by condensers, gas-liquid separators or filters
• CPC Class Codes: H01M 8/04268 : Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/0612 : from carbon-containing material
• CPC Class Codes: H01M 8/0625 : in a modular combined reactor/fuel cell structure
• CPC Class Codes: H01M 8/0668 : Removal of carbon monoxide or carbon dioxide
• CPC Class Codes: H01M 8/0675 : Removal of sulfur
• CPC Class Codes: H01M 8/12 : operating at high temperature, e.g. with stabilised ZrO2 electrolyte
• CPC Class Codes: H01M 8/18 : Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
• CPC Class Codes: H01M 8/2432 : Grouping of unit cells of planar configuration
• CPC Class Codes: H01M 8/249 : comprising two or more groupings of fuel cells, e.g. modular assemblies
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 20/10 : Process efficiency
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Abstract

A high temperature fuel cell stack system, such as a solid oxide fuel cell system, with an improved balance of plant efficiency includes a thermally integrated reformer, combustor and the fuel cell stack.

Claims

1. A solid oxide fuel cell system, comprising:

a combustor comprising a combustor conduit;

a plurality of solid oxide fuel cell stacks; and

a reformer adapted to reform a hydrocarbon fuel to a hydrogen containing reaction product and to provide the reaction product to the stacks;

wherein;

at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks is adapted to be heated by cathode exhaust of the stacks, and the reformer is adapted to be heated by the combustor which is thermally integrated with the reformer via the combustor conduit, and by at least one of radiative and convective heating from the stacks across a gap between the stacks and the reformer;

the reformer surrounds the combustor conduit;

the plurality of solid oxide fuel cell stacks surround the reformer, such that the reformer is sandwiched between the combustor conduit and the plurality of the solid oxide fuel cell stacks; and

the at least one wall of the reformer in combination with the stacks form a cathode exhaust conduit of the stacks.

2. The system of claim 1, wherein the cathode exhaust conduit of the stacks is thermally integrated with the reformer and is adapted to heat the reformer using the cathode exhaust of the stacks.

3. The system of claim 2, wherein a first portion of the cathode exhaust conduit comprises a space located between the stacks and the reformer, into which space the cathode exhaust is provided from the stacks.

4. The system of claim 3, wherein the cathode exhaust conduit is connected to an inlet of the combustor.

5. The system of claim 3, wherein the gap between the reformer and the stacks comprises the cathode exhaust conduit of the stacks.

6. The system of claim 5, wherein an outer reformer wall contains fins which extend into the cathode exhaust conduit and an inner reformer wall contains fins which extend into the combustor.

7. The system of claim 1, wherein the combustor comprises the combustor conduit and a combustion zone containing a combustor catalyst.

8. The system of claim 7, wherein the combustor shares at least one wall with the reformer.

9. The system of claim 8, wherein:

the reformer comprises a catalyst containing cylinder;

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises an outer wall of the cylinder facing the plurality of solid oxide fuel cell stacks;

and the combustor combustion zone comprises a catalyst containing tube located in the cylinder core and the combustor tube wall comprises an inner wall of the reformer cylinder.

10. The system of claim 8, wherein:

the reformer comprises a plurality of catalyst containing plate shaped reformer portions, each of which shares one wall with a catalyst containing plate shaped combustor combustion zone; and

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises a plurality of walls of the plurality of reformer portions facing the plurality of the solid oxide fuel cell stacks.

11. The system of claim 7, further comprising a catalytic partial oxidation reactor adapted to provide hydrogen into the combustor during system start up.

12. The system of claim 7, further comprising an air heat exchanger, wherein an outlet of the combustor is connected to a first inlet of the air heat exchanger, an air inlet conduit is connected to a second inlet of the air heat exchanger, and a first outlet of the air heat exchanger is connected to a cathode inlet of the stacks.

13. The system of claim 1, further comprising:

a condenser adapted to separate water from a stack anode exhaust;

an evaporator adapted to evaporate water to be provided into a stack inlet fuel stream; and

a fuel-steam mixer adapted to mix the evaporated water and the stack inlet fuel stream.

14. The system of claim 1, further comprising:

a desulfurizer fluidly connected to fuel inlets of the stacks; and

a water-gas shift reactor fluidly connected to fuel outlets of the stacks;

wherein the desulfurizer and the water-gas shift reactor are thermally integrated with each other.

15. The system of claim 1, further comprising:

a connecting conduit connecting a fuel inlets of the stacks with an outlet of the reformer;

a hydrocarbon fuel inlet conduit connected to an inlet of the reformer; and

a hydrocarbon fuel by-pass line fluidly connected to the fuel inlets of the stacks, wherein the by-pass line is adapted to provide unreformed hydrocarbon fuel into the fuel inlets of the stacks.

16. The system of claim 1, further comprising:

a hydrogen separation device fluidly connected to the fuel outlets of the stacks;

a carbon monoxide separation device fluidly connected to the fuel outlets of the stacks;

a hydrocarbon fuel inlet conduit fluidly connected to fuel inlets of the stacks; and

a carbon monoxide recycle conduit, whose inlet is fluidly connected to an outlet of the carbon monoxide separation device and whose outlet is fluidly connected to the fuel inlets of the stacks.

17. The system of claim 1, further comprising:

a PSA separation device fluidly connected to fuel outlets of the stacks; and

a thermal output of the stacks in addition to the fuel outlets is thermally integrated with at least a first column of the PSA device.

18. The system of claim 1, wherein the combustor conduit, the reformer and the stacks are located in a hot box.

19. The system of claim 18, wherein:

the combustor conduit is located in a middle of the hot box; and

the reformer comprises a plurality of conduits which surround the combustor conduit.

20. A solid oxide fuel cell system, comprising:

a combustor;

a plurality of solid oxide fuel cell stacks; and

a reformer adapted to reform a hydrocarbon fuel to a hydrogen containing reaction product and to provide the reaction product to the stacks;

wherein;

at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks is adapted to be heated by cathode exhaust of the stacks, and the reformer is adapted to be heated by the combustor which is thermally integrated with the reformer, and by at least one of radiative and convective heating from the stacks across a gap between the stacks and the reformer;

the reformer surrounds the combustor;

the plurality of solid oxide fuel cell stacks surround the reformer, such that the reformer is sandwiched between the combustor and the plurality of the solid oxide fuel cell stacks; and

the at least one wall of the reformer in combination with the stacks form a cathode exhaust conduit of the stacks.

21. The system of claim 20, wherein a first portion of the cathode exhaust conduit comprises a space located between the stacks and the reformer, into which space the cathode exhaust is provided from the stacks.

22. The system of claim 20, wherein:

the reformer comprises a catalyst containing cylinder; and

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises an outer wall of the cylinder facing the plurality of solid oxide fuel cell stacks.

23. The system of claim 20, wherein:

the reformer comprises a plurality of catalyst containing plate shaped reformer portions, each of which shares one wall with a catalyst containing plate shaped combustor combustion zone; and

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises a plurality of walls of the plurality of reformer portions facing the plurality of the solid oxide fuel cell stacks.

24. A solid oxide fuel cell system, comprising:

a combustor;

a plurality of solid oxide fuel cell stacks;

a reformer adapted to reform a hydrocarbon fuel to a hydrogen containing reaction product and to provide the reaction product to the stacks; and

a cathode exhaust conduit of the stacks which is thermally integrated with the reformer and which is adapted to heat the reformer using the cathode exhaust of the stacks;

wherein;

at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks is adapted to be heated by cathode exhaust of the stacks passing through the cathode exhaust conduit, and the reformer is adapted to be heated by the combustor which is thermally integrated with the reformer, and by at least one of radiative and convective heating from the stacks across a gap between the stacks and the reformer;

the reformer surrounds the combustor; and

the plurality of solid oxide fuel cell stacks surround the reformer, such that the reformer is sandwiched between the combustor and the plurality of the solid oxide fuel cell stacks; and

the at least one wall of the reformer in combination with the stacks form the cathode exhaust conduit.

25. The system of claim 24, wherein a first portion of the cathode exhaust conduit comprises a space located between the stacks and the reformer, into which space the cathode exhaust is provided from the stacks.

26. The system of claim 24, wherein:

the reformer comprises a catalyst containing cylinder; and

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises an outer wall of the cylinder facing the plurality of solid oxide fuel cell stacks.

27. The system of claim 24, wherein:

the reformer comprises a plurality of catalyst containing plate shaped reformer portions, each of which shares one wall with a catalyst containing plate shaped combustor combustion zone; and

the at least one wall of the reformer facing at least one of the plurality of the solid oxide fuel cell stacks comprises a plurality of walls of the plurality of reformer portions facing the plurality of the solid oxide fuel cell stacks.