Fuel Cell System Containing Anode Tail Gas Oxidizer and Hybrid Heat Exchanger/Reformer

• US 20130011757A1
• Filed: 09/14/2012
• Published: 01/10/2013
• Est. Priority Date: 02/19/2008
• Status: Active Grant

• Current Assignee: Bloom Energy Corporation
• Original Assignee: Bloom Energy Corporation
• Inventors: VENKATARAMAN, Swaminathan, PERRY, Martin
• Granted Patent: US 8,535,839 B2
• Time in Patent Office: Days
• US Class Current: 429/419
• CPC Class Codes: C01B 2203/066 with fuel cells
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• 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 8/0631 Reactor construction specially adapted for combination reactor/fuel cell hydrogen C01B3/00; reactors for physicochemical processes B01J19/00
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system includes at least one fuel cell stack, a fuel inlet conduit, and a fuel heat exchanger containing a fuel reformation catalyst. The fuel heat exchanger is connected to the fuel inlet conduit and to at least one fuel cell system exhaust conduit which in operation provides a high temperature exhaust stream to the fuel heat exchanger. The fuel heat exchanger is thermally integrated with an anode tail gas oxidizer (ATO) exhaust conduit such that in operation an ATO exhaust stream in the ATO exhaust conduit heats a fuel inlet stream passing through the heat exchanger.

Claims

1. A fuel cell system, comprising:

at least one fuel cell stack;

a fuel inlet conduit; and

a fuel heat exchanger containing a fuel reformation catalyst, wherein the fuel heat exchanger is connected to the fuel inlet conduit and to at least one fuel cell system exhaust conduit which in operation provides a high temperature exhaust stream to the fuel heat exchanger.

5. The system of claim 1, wherein the at least one fuel cell system exhaust conduit comprises a fuel exhaust conduit which in operation provides a fuel exhaust stream from the at least one fuel cell stack to the fuel heat exchanger, and the at least one fuel cell stack comprises at least one SOFC stack.

6. The system of claim 1, wherein the fuel heat exchanger comprises a multi-stream heat exchanger which contains passages for at least three flow streams.

7. The system of claim 6, further comprising an anode tail gas oxidizer (ATO).

8. The system of claim 1, wherein the fuel heat exchanger comprises fins coated with the fuel reformation catalyst.

9. The system of claim 8, wherein the fuel reformation catalyst comprises at least one of nickel or rhodium.

10. The system of claim 1, further comprising a hydrocarbon fuel source connected to the fuel inlet conduit.

2. A method of operating fuel cell system, comprising:

providing a hydrocarbon fuel inlet stream into a fuel heat exchanger containing a fuel reformation catalyst;

reforming the hydrocarbon fuel in the fuel heat exchanger;

providing a reformed fuel from the fuel heat exchanger into at least one fuel cell stack; and

providing at least one exhaust stream from the at least one fuel cell stack into the fuel heat exchanger to exchange heat with the hydrocarbon fuel inlet stream.

11. The method of claim 2, wherein the at least one exhaust stream comprises a fuel exhaust stream, and the at least one fuel cell stack comprises at least one SOFC stack.

12. The method of claim 2, wherein the fuel heat exchanger comprises a multi-stream heat exchanger which contains passages for at least three flow streams.

13. The method of claim 12, further comprising an anode tail gas oxidizer (ATO).

14. The method of claim 13, further comprising:

providing the hydrocarbon fuel inlet stream and an air inlet stream through the multi-stream heat exchanger to the at least one fuel cell stack;

providing an ATO fuel inlet stream to the ATO;

providing a cathode exhaust stream from the at least one fuel cell stack to the ATO; and

providing an ATO exhaust stream from the ATO and a fuel exhaust stream from the at least one stack into the multi-stream heat exchanger to heat the hydrocarbon fuel inlet stream and the air inlet stream.

15. The method of claim 14, wherein the at least one fuel cell stack, the ATO and the multi-stream heat exchanger are located inside a hotbox.

16. The method of claim 2, wherein the fuel heat exchanger comprises fins coated with the fuel reformation catalyst.

17. The method of claim 16, wherein the fuel reformation catalyst comprises at least one of nickel or rhodium.

18. The method of claim 17, wherein rhodium is located in a leading segment and nickel is located in a trailing segment of the fuel heat exchanger.

19. The method of claim 18, wherein the hydrocarbon fuel inlet stream is switched between a higher and a lower hydrocarbon fuel inlet stream.

3. A fuel cell system, comprising:

at least one fuel cell stack;

an anode tail gas oxidizer (ATO);

an ATO exhaust conduit; and

at least one device selected from a fuel heat exchanger, an external reformer, or a fuel heat exchanger containing a fuel reformation catalyst;

wherein the at least one device is thermally integrated with the ATO exhaust conduit such that in operation an ATO exhaust stream in the ATO exhaust conduit heats a fuel inlet stream passing through the at least one device.

20. The system of claim 3, wherein the at least one device comprises the fuel heat exchanger containing a fuel reformation catalyst.

21. The system of claim 20, wherein the fuel heat exchanger is connected to a fuel exhaust conduit which in operation provides a fuel exhaust stream from the at least one fuel cell stack to the fuel heat exchanger, and the at least one fuel cell stack comprises at least one SOFC stack.

22. The system of claim 20, wherein the fuel heat exchanger shares at least one wall with the ATO exhaust conduit.

23. The system of claim 3, further comprising a hydrocarbon fuel source connected to the fuel inlet conduit.

4. A method of operating fuel cell system, comprising:

providing a first fuel inlet stream and an air exhaust stream from a fuel cell stack into an anode tail gas oxidizer (ATO);

oxidizing the first fuel inlet stream in the ATO;

providing a second fuel inlet stream into the fuel heat exchanger;

providing a fuel exhaust stream from a fuel cell stack into the fuel heat exchanger;

heating the second fuel inlet stream in the fuel heat exchanger using both the fuel exhaust stream and the ATO exhaust stream; and

providing second fuel inlet stream into the fuel cell stack after the step of heating.

24. The method of claim 4, further comprising reforming the second fuel inlet stream in the fuel heat exchanger.

25. The method of claim 4, wherein the step of heating comprises passing the ATO exhaust stream adjacent to a wall of the fuel heat exchanger.

26. The method of claim 4, further comprising providing the ATO exhaust stream into an air heat exchanger and heating an air inlet stream in the air heat exchanger using the ATO exhaust stream.