Ammonia fueled SOFC system

• US 8,916,300 B2
• Filed: 09/07/2012
• Issued: 12/23/2014
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: Bloom Energy Corporation
• Original Assignee: Bloom Energy Corporation
• Inventors: McElroy, James, Ballantine, Arne, Gottmann, Matthias
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): Zhang, Haixia
• Application Number:
  US13/606,765
• Publication Number:
  US 20140072889A1
• Time in Patent Office: 837 Days
• Field of Search: None
• US Class Current: 429/411
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04156 with product water removal
• CPC Class Codes: H01M 8/0606 with means for production of gaseous reactants
• CPC Class Codes: H01M 8/0662 Treatment of gaseous reactants or gaseous residues, e.g. cleaning
• CPC Class Codes: H01M 8/145 comprising carbonates
• CPC Class Codes: H01M 8/222 Fuel cells in which the fuel is based on compounds containing nitrogen, e.g. hydrazine, ammonia
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Systems and methods are provided in which ammonia is used as a fuel source for solid oxide fuel cell systems. In the various aspects a high temperature fuel cell stack exhaust stream is recycled through one or more separation or conversion devices to create a purified recycled fuel exhaust stream that is recycled back into the fuel inlet stream of the high temperature fuel cell stack. In various aspects a nitrogen separator may remove nitrogen from the recycled fuel cell stack exhaust stream, a water separator may remove water from the recycled fuel cell stack exhaust stream, and/or an ammonia reactor and hydrogen separator may be used to condition the fuel inlet stream of the high temperature fuel cell stack. In a further aspect a molten carbonate fuel cell and/or Sabatier reactor may be used to condition the fuel inlet stream of the high temperature fuel cell stack.

Claims

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

providing a fuel inlet stream comprising ammonia;

providing the fuel inlet stream into a solid oxide fuel cell stack;

operating the solid oxide fuel cell stack to generate a fuel exhaust stream;

separating at least a portion of hydrogen from a first portion of the fuel exhaust stream using a hydrogen separator to generate a purified fuel exhaust stream, wherein the hydrogen separator is a plurality of cascaded hydrogen pumps;

recycling the purified fuel exhaust stream to the fuel inlet stream;

providing a portion of the fuel inlet stream comprising ammonia to an ATO, wherein the ATO does not receive any portion of the fuel exhaust stream; and

providing air from the solid oxide fuel cell stack to the ATO.