High-efficiency dual-stack molten carbonate fuel cell system

• US 8,236,458 B2
• Filed: 10/18/2011
• Issued: 08/07/2012
• Est. Priority Date: 08/19/2008
• Status: Active Grant

• Current Assignee: Fuelcell Energy Ltd.
• Original Assignee: Fuelcell Energy Ltd.
• Inventors: Jahnke, Fred C., Farooque, Mohammad, Ghezel-Ayagh, Hossein
• Primary Examiner(s): HYEON, HAE M
• Application Number:
  US13/275,524
• Publication Number:
  US 20120034538A1
• Time in Patent Office: 294 Days
• Field of Search: 429/415, 429/416, 429/425, 429/423
• US Class Current: 429/415
• CPC Class Codes: H01M 2008/147 Fuel cells with molten carbonates
• CPC Class Codes: H01M 8/04291 Arrangements for managing water in solid electrolyte fuel cell systems H01M8/04119 takes precedence
• CPC Class Codes: H01M 8/04701 Temperature
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/0612 from carbon-containing material
• CPC Class Codes: H01M 8/0637 Direct internal reforming at the anode of the fuel cell
• 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

Abstract

A dual stack fuel cell system comprising a first fuel cell stack comprising a first anode side, adapted to receive fuel and to output a first anode exhaust, and a first cathode side, a second fuel cell stack comprising a second anode side, adapted to receive processed anode exhaust derived from the first anode exhaust and to output a second anode exhaust, and a second cathode side, adapted to receive oxidant gas and to output a first cathode exhaust, wherein the first cathode side receives at least the first cathode exhaust outputted from the second cathode side; and wherein the first fuel cell stack includes indirect internal reforming and the second fuel cell stack may not include any indirect internal reforming.

Claims

1. A dual stack fuel cell system comprising:

a first fuel cell stack comprising a first anode side, adapted to receive fuel and to output a first anode exhaust, and a first cathode side;

a second fuel cell stack comprising a second anode side, adapted to receive processed anode exhaust derived from said first anode exhaust and to output a second anode exhaust, and a second cathode side, adapted to receive oxidant gas and to output a first cathode exhaust;

wherein said first cathode side receives at least said first cathode exhaust outputted from said second cathode side; and

wherein said first fuel cell stack includes indirect internal reforming and said second fuel cell stack does not include any indirect internal reforming.

2. A dual stack fuel cell system in accordance with claim 1, wherein said second fuel cell stack is one of a non-reforming fuel cell stack and a direct internal reforming (DIR) fuel cell stack.

3. A dual stack fuel cell system in accordance with claim 2, wherein said first fuel cell stack further includes direct internal reforming (DIR).

4. A dual stack fuel cell system in accordance with claim 2, further comprising at least one of:

a cooling assembly including at least one cooling member for cooling said first anode exhaust;

a reactor assembly including at least one of a shift reactor and a methanation reactor for converting carbon monoxide in said first anode exhaust to respectively at least one of methane and hydrogen; and

a water recovery assembly for recovering water from said first anode exhaust;

wherein said processed anode exhaust is derived by at least one of cooling said first anode exhaust in said cooling assembly, reacting said first anode exhaust in said reactor assembly and recovering water from said first anode exhaust in said water recovery assembly.

5. A dual stack fuel cell system in accordance with claim 4, further comprising an oxidizer assembly adapted to receive said second anode exhaust from said second anode side and inlet air and to oxidize said second anode exhaust with said inlet air to produce said oxidant gas.

6. A dual stack fuel cell system in accordance with claim 5, wherein said cooling assembly comprises a first heat exchanger assembly for cooling said first anode exhaust by transferring heat from said first anode exhaust to said processed anode exhaust and a second heat exchanger assembly for further cooling said first anode exhaust by transferring heat from said first anode exhaust to said inlet air before said inlet air is conveyed to said oxidizer.

7. A dual stack fuel cell system in accordance with claim 4, wherein said water recovery assembly is adapted to receive said first anode exhaust cooled by said cooling assembly and reacted in said reactor assembly, and comprises:

a packed tower assembly, adapted to receive said first anode exhaust and recycle water, for condensing at least a portion of the water in said first anode exhaust and outputting water separated anode exhaust and condensed water comprising said water recovered from said first anode exhaust and recycle water; and

a recycle path for cooling and conveying a first portion of the condensed water to said packed tower assembly for use as recycle water,

wherein a second portion of said condensed water is outputted from said water recovery assembly and used for humidifying said fuel before conveying said fuel to said first anode side.

8. A dual stack fuel cell system in accordance with claim 7, wherein said processed anode exhaust comprises said water separated anode exhaust.

9. A dual stack fuel cell system in accordance with claim 7, wherein supplemental fuel is added to said water separated anode exhaust and said processed anode exhaust comprises said water separated anode exhaust and said supplemental fuel.

10. A dual stack fuel cell system in accordance with claim 5, wherein a first portion of said oxidant gas produced by said oxidizer is conveyed to said second cathode side and a second portion of said oxidant gas is mixed with said first cathode exhaust from said second cathode side and conveyed to said first cathode side.

11. A dual stack fuel cell system in accordance with claim 10, wherein said first cathode side is further adapted to receive supplemental air from an external source, and

wherein the temperature in said first fuel cell stack is controlled by adjusting the flow of supplemental air to said first cathode side so as to increase the amount of supplemental air flow to said first cathode side to decrease the temperature in said first fuel cell stack and to decrease the amount of supplemental air flow to said first cathode side to increase the temperature in said first fuel cell stack.

12. A dual stack fuel cell system in accordance with claim 5, further comprising an anode exhaust recycle path for passing a portion of said processed anode exhaust to said first fuel cell stack.

13. A dual stack fuel cell system in accordance with claim 1, wherein said first cathode side outputs a second cathode exhaust and wherein heat from said second cathode exhaust is used for preheating said fuel supplied to said first anode side.

14. A dual stack fuel cell system in accordance with claim 4, further comprising a blower for increasing the pressure of said first anode exhaust and for controlling anode-side pressure of said first fuel cell stack.

15. A dual stack fuel cell system in accordance with claim 12, wherein said anode exhaust recycle path passes a portion of the processed anode exhaust outputted from said water recovery assembly to said first anode side.

16. A dual stack fuel cell system in accordance with claim 1, further comprising an inlet fuel bypass path for bypassing a portion of the fuel around said first fuel cell stack to combine the bypassed portion of the fuel with the first anode exhaust.

17. A dual fuel cell stack system in accordance with claim 15, wherein the power output of said second fuel cell stack is varied and the flow of said fuel through said inlet fuel bypass path is correspondingly adjusted with power output.