High temperature fuel cell system with integrated heat exchanger network

• US 20060251934A1
• Filed: 05/09/2005
• Published: 11/09/2006
• Est. Priority Date: 05/09/2005
• Status: Abandoned Application

• Current Assignee: Bloom Energy Corporation, Modine Manufacturing Company
• Original Assignee: Bloom Energy Corporation, Modine Manufacturing Company
• Inventors: Venkataraman, Swaminathan, Bandhauer, Todd M., Valensa, Jeroen, Reinke, Michael J.
• Application Number:
  US11/124,120
• Publication Number:
  US 20060251934A1
• Time in Patent Office: Days
• US Class Current: 429/414
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04126 Humidifying
• CPC Class Codes: H01M 8/04164 by condensers, gas-liquid separators or filters
• CPC Class Codes: H01M 8/0612 from carbon-containing material
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system includes a fuel cell stack, a heat transfer device which is adapted to transfer heat from a cathode exhaust stream of the fuel cell stack to water to be provided to an fuel inlet stream, a reformer adapted to reform a hydrocarbon fuel to a hydrogen containing reaction product and to provide the reaction product to the fuel cell stack, and a combustor which is thermally integrated with the reformer.

Claims

1. A fuel cell system, comprising:

a fuel cell stack;

a heat transfer device adapted to transfer heat from a cathode exhaust stream of the fuel cell stack to water to be provided to a fuel inlet stream;

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

a combustor which is thermally integrated with the reformer.

2. The system of claim 1, wherein the fuel cell stack comprises a solid oxide fuel cell stack.

3. The system of claim 2, further comprising:

a fuel preheater which is adapted to heat the fuel inlet stream using heat from the fuel cell stack anode exhaust stream;

a cathode recuperator heat exchanger which is adapted to heat an air inlet stream using heat from the cathode exhaust stream;

an air preheater heat exchanger which is adapted to preheat the air inlet stream using heat from the anode exhaust stream;

a steam-fuel mixer which is adapted to mix the fuel inlet stream with the steam provided from an evaporator; and

a hot box containing the fuel cell stack, the reformer, the combustor, the fuel preheater and the cathode recuperator.

4. The system of claim 3, further comprising:

a plurality of connecting conduits;

a water gas shift reactor adapted to convert at least a portion of water vapor in the fuel cell stack anode exhaust stream into free hydrogen;

a condenser adapted to condense water vapor in the anode exhaust stream into liquid water; and

a hydrogen recovery system adapted to recover hydrogen from the anode exhaust stream after the anode exhaust stream passes through the condenser.

5. The system of claim 1, further comprising a means for providing between 2.5 and 6.5 times as much air into the fuel cell stack as required for the fuel cell stack to generate electricity.

6. The system of claim 2, further comprising a means for providing between 3 and 4.5 times as much air into the fuel cell stack as required for the fuel cell stack to generate electricity.

7. The system of claim 1, wherein the fuel cell stack cathode exhaust outlet is operatively connected to an inlet of the combustor.

8. A fuel cell system, comprising:

a fuel cell stack;

a first means for evaporating water to steam using heat from a fuel cell stack cathode exhaust stream;

a second means for providing the steam into a fuel inlet stream being directed to the fuel cell stack;

a third means for reforming a hydrocarbon fuel to a hydrogen containing reaction product and for providing the reaction product to the fuel cell stack; and

a fourth means for combusting a fuel and an oxidizer, wherein the fourth means is thermally integrated with the third means.

9. The system of claim 8, wherein the fuel cell stack cathode exhaust outlet is operatively connected to an inlet of the fourth means.

10. The system of claim 8, wherein the fuel cell stack comprises a solid oxide fuel cell stack.

11. The system of claim 8, further comprising a fifth means for providing between 2.5 and 6.5 times as much air into the fuel cell stack as required for the fuel cell stack to generate electricity.

12. A method of operating a fuel cell system, comprising:

operating a fuel cell stack to generate electricity;

evaporating water to steam using heat from a fuel cell stack cathode exhaust stream;

providing the steam into a fuel inlet stream being directed to the fuel cell stack;

reforming the fuel comprising at least one of methane and natural gas in the fuel inlet stream in a reformer;

providing the reformed fuel into the anode inlet of the fuel cell stack;

providing a fuel and an oxidizer into a combustor; and

providing combustion heat from the combustor to the reformer.

13. The method of claim 12, wherein the fuel cell stack comprises a solid oxide fuel cell stack.

14. The method of claim 12, wherein the step of providing an oxidizer into the combustor comprises providing the fuel cell stack cathode exhaust stream into the combustor.

15. The method of claim 12, further comprising transferring heat from the cathode exhaust stream to the reformer by passing the cathode exhaust stream adjacent to the reformer.

16. The method of claim 12, further comprising:

converting at least a portion of water vapor in a fuel cell stack anode exhaust stream into free hydrogen;

condensing the water vapor in the anode exhaust stream into liquid water; and

recovering hydrogen from the anode exhaust stream after the step of condensing.

17. The method of claim 12, further comprising providing between 2.5 and 6.5 times as much air into the fuel cell stack as required for the fuel cell stack to generate electricity.

18. A method of operating a fuel cell system, comprising:

operating a fuel cell stack to generate electricity;

evaporating water to steam using heat from a fuel cell stack cathode exhaust stream;

providing the steam into a fuel inlet stream being directed to the fuel cell stack;

converting at least a portion of water vapor in a fuel cell stack anode exhaust stream into free hydrogen;

condensing the water vapor in the anode exhaust stream into liquid water; and

recovering hydrogen from the anode exhaust stream after the step of condensing.

19. A fuel cell system, comprising:

a fuel cell stack;

a heat transfer device adapted to transfer heat from a cathode exhaust stream of the fuel cell stack to water to be provided to a fuel inlet stream;

a water gas shift reactor adapted to convert at least a portion of water vapor in the fuel cell stack anode exhaust stream into free hydrogen;

a condenser adapted to condense water vapor in the anode exhaust stream into liquid water; and

a hydrogen recovery system adapted to recover hydrogen from the anode exhaust stream after the anode exhaust stream passes through the condenser.

20. The system of claim 19, further comprising:

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

a combustor which is thermally integrated with the reformer.