Fuel cell system with electrochemical anode exhaust recycling

• US 20070178338A1
• Filed: 07/24/2006
• Published: 08/02/2007
• Est. Priority Date: 07/25/2005
• Status: Active Grant

• Current Assignee: Bloom Energy Corporation
• Original Assignee: Bloom Energy Corporation
• Inventors: Venkataraman, Swaminathan, McElroy, James
• Granted Patent: US 8,101,307 B2
• Time in Patent Office: Days
• US Class Current: 429/411
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2258/0208 from fuel cells
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: H01M 8/0289 Means for holding the electrolyte solid polymer electrolytes H01M8/1018
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/0681 Reactant purification by the use of electrochemical cells
• CPC Class Codes: H01M 8/08 Fuel cells with aqueous electrolytes
• CPC Class Codes: H01M 8/103 having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh]
• CPC Class Codes: H01M 8/1048 Ion-conducting additives, e.g. ion-conducting particles, heteropolyacids, metal phosphate or polybenzimidazole with phosphoric acid
• CPC Class Codes: H01M 8/2425 High-temperature cells with solid electrolytes
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• 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 method of operating a fuel cell system includes providing a fuel inlet stream into a fuel cell stack, operating the fuel cell stack to generate electricity and a hydrogen containing fuel exhaust stream, separating at least a portion of hydrogen contained in the fuel exhaust stream using a high temperature, low hydration ion exchange membrane cell stack, and providing the hydrogen separated from the fuel exhaust stream into the fuel inlet stream.

Claims

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

providing a fuel inlet stream into a fuel cell stack;

operating the fuel cell stack to generate electricity and a hydrogen containing fuel exhaust stream;

separating at least a portion of hydrogen contained in the fuel exhaust stream using a high temperature, low hydration ion exchange membrane cell stack; and

providing the hydrogen separated from the fuel exhaust stream into the fuel inlet stream.

2. The method of claim 1, wherein the high temperature, low hydration ion exchange membrane cell stack comprises a stack of acid doped non-fluorinated ion exchange ionomer membrane cells.

3. The method of claim 2, wherein each membrane of the membrane cells comprises a polybenzimidazole (PBI) membrane doped with sulfuric or phosphoric acid.

4. The method of claim 1, further comprising lowering a temperature of the fuel exhaust stream to between 120 C and 200 C prior to the step of separating at least a portion of hydrogen.

5. A fuel cell system, comprising:

a fuel cell stack;

a high temperature, low hydration ion exchange membrane cell stack;

a first conduit which operatively connects a fuel exhaust outlet of the fuel cell stack to a first inlet of the high temperature, low hydration ion exchange membrane cell stack; and

a second conduit which operatively connects an outlet of the a high temperature, low hydration ion exchange membrane cell stack to the fuel cell stack fuel inlet.

6. The system of claim 5, wherein the high temperature, low hydration ion exchange membrane cell stack comprises a stack of acid doped non-fluorinated ion exchange ionomer membrane cells.

7. The system of claim 6, wherein each membrane of the membrane cells comprises a polybenzimidazole (PBI) membrane doped with sulfuric or phosphoric acid.