Solid oxide fuel cell system with hydrogen pumping cell with carbon monoxide tolerant anodes and integrated shift reactor

Patent metadata

Field	Value
Publication number	US-2020328445-A1
Application number	US-202016840801-A
Country	US
Kind code	A1
Filing date	Apr 6, 2020
Priority date	Apr 12, 2019
Publication date	Oct 15, 2020
Grant date	—

Abstract

A fuel cell system includes at least one of plural electrochemical pump separators to separate carbon dioxide from a fuel exhaust stream or a combination of a gas separator and a fuel exhaust cooler located outside a hotbox.

First claim

What is claimed is:

1 . A fuel cell system, comprising:
a fuel cell stack; an anode tail gas oxidizer (ATO); first and second electrochemical hydrogen pump separators that each comprise an electrolyte disposed between a cathode and an anode; a fuel exhaust conduit that fluidly connects a fuel exhaust outlet of the fuel cell stack to a splitter; a first separation conduit that fluidly connects an outlet of the splitter to an anode inlet of the first pump separator; a second separation conduit that fluidly connects an anode outlet of the first pump separator to an anode inlet of the second pump separator; an ATO inlet conduit that fluidly connects a cathode outlet of the first electrochemical pump separator to the anode tail gas oxidizer; a hydrogen conduit that fluidly connects a cathode outlet of the second electrochemical pump separator to a fuel inlet of the fuel cell stack; and a byproduct conduit that fluidly connects an anode outlet of the second electrochemical pump separator to a carbon dioxide use or storage device.

2 . The fuel cell system of claim 1 , wherein:
the first separation conduit is configured to provide fuel exhaust generated by the fuel cell stack to the first hydrogen pump separator; the first hydrogen pump separator is configured to separate hydrogen from the provided fuel exhaust; and the ATO inlet conduit is configured to provide hydrogen output from the first hydrogen pump separator to the ATO.

3 . The fuel cell system of claim 2 , wherein:
the second separation conduit is configured to provide fuel exhaust output from the first hydrogen pump separator to the second hydrogen pump separator; the second hydrogen pump separator is configured to separate hydrogen from the provided fuel exhaust; the hydrogen conduit is configured to provide hydrogen output from the second hydrogen pump separator to a fuel inlet stream provided to the fuel cell stack; and the byproduct conduit is configured to provide a byproduct stream comprising carbon dioxide output from the second hydrogen pump separator to the carbon dioxide use or storage device.

4 . The fuel cell system of claim 3 , wherein the carbon dioxide use or storage device comprises:
a dryer configured to remove water from the carbon dioxide stream; and a cryogenic storage device configured to store carbon dioxide output from the drier as dry ice.

5 . The fuel cell system of claim 2 , further comprising:
a fuel inlet conduit configured to fluidly connect a fuel inlet of the fuel cell stack to a fuel source; a recycling conduit fluidly connecting an outlet of the splitter to the fuel inlet conduit; a mixer operatively connected to the hydrogen conduit and the recycling conduit, the mixer configured to mix hydrogen output by the second hydrogen pump separator with fuel exhaust provided by the splitter.

6 . The fuel cell system of claim 5 , further comprising:
a water-gas shift reactor operatively connected to the fuel exhaust conduit; and a Venturi device operatively connected to the recycling conduit.

7 . A method of operating the fuel cell system of claim 3 , comprising:
operating the first hydrogen pump separator in a constant current mode to control an amount of hydrogen that is provided to the ATO; and operating the second hydrogen pump separator in a constant voltage mode, such that substantially all of the hydrogen is removed from the received fuel exhaust.

8 . A fuel cell system comprising:
a hotbox; a fuel cell stack disposed in the hotbox; an anode tail gas oxidizer (ATO) disposed in the hotbox; a fuel inlet conduit fluidly connecting a fuel source to an inlet of the fuel cell stack; a fuel exhaust condenser disposed outside of the hotbox configured to condense water from fuel exhaust generated by the fuel cell stack and output from the hotbox; a fuel exhaust separator configured to remove water from fuel exhaust received from the fuel exhaust condenser; a fuel exhaust conduit fluidly connecting a fuel exhaust outlet of the fuel cell stack to the fuel exhaust condenser; a recycling conduit fluidly connecting the fuel exhaust separator to the fuel inlet conduit; an ATO inlet conduit fluidly connecting the recycling conduit to the ATO; and a recycling valve configured to selectively control fuel exhaust flow through the recycling conduit and into the ATO inlet conduit.

9 . The fuel cell system of claim 8 , further comprising:
a bleed valve disposed on the recycling conduit, upstream of the recycling valve, with respect to a fuel exhaust flow direction through the recycling conduit; and a bleed conduit fluidly connecting the recycling conduit to the ATO inlet conduit; wherein the bleed valve is configured to purge impurities from the fuel exhaust or provide back pressure to equalize anode and cathode pressures in the fuel cell stack.

10 . The fuel cell system of claim 8 , further comprising:
a fuel heat exchanger disposed in the hotbox and configured to heat a fuel inlet stream in the fuel inlet conduit using fuel exhaust output from the fuel cell stack; and an anode exhaust cooler disposed in the hotbox and configured to cool fuel exhaust output from the fuel heat exchanger using air provided to the fuel cell stack.

11 . A method of operating the fuel cell system of claim 8 , comprising operating the recycling valve to provide fuel exhaust to the ATO during startup operation of the system and prevent the fuel exhaust from being provided to the ATO during steady-state operation of the system.

12 . The method of claim 11 , wherein:
the fuel exhaust separator reduces a water content of the fuel exhaust to 12 vol % or less; and a fuel inlet stream in the fuel inlet conduit is hydrogen fuel stream, and the fuel exhaust is substantially free of carbon.

13 . A method of operating the cell system of claim 8 , further comprising using recirculating air in a cabinet containing at least one of the hot box or power conditioning subsystem to cool the fuel exhaust condenser.

14 . A fuel cell system comprising:
a hotbox; a fuel cell stack disposed in the hotbox; an anode tail gas oxidizer (ATO) disposed in the hotbox; a fuel inlet conduit fluidly connecting a fuel source to an inlet of the fuel cell stack; an external anode exhaust cooler located outside the hotbox; a fuel exhaust conduit fluidly connecting a fuel exhaust outlet of the fuel cell stack to the external anode exhaust cooler; a recycling conduit fluidly connecting the external anode exhaust cooler to the fuel inlet conduit; a fuel exhaust processing conduit fluidly connected to the recycling conduit; and a gas separator fluidly connected to the fuel exhaust processing conduit and configured to separate fuel exhaust received from the fuel exhaust processing conduit into streams of water, carbon dioxide, and hydrogen.

15 . The fuel cell system of claim 14 , wherein the gas separator comprises:
a heat exchanger configured to cool the received fuel exhaust; a compressor configured to compress the cooled fuel exhaust; a water separator configured to remove water from the compressed fuel exhaust; a carbon dioxide condenser configured to condense the compressed fuel exhaust to form liquid carbon dioxide; and a distillation column configured to separate the liquid carbon dioxide from hydrogen in the condensed fuel exhaust.

16 . The fuel cell system of claim 14 , further comprising:
a hydrogen recycling conduit fluidly connecting a hydrogen outlet of the gas separator to the fuel inlet conduit; an ATO inlet conduit fluidly connecting the hydrogen recycling c

Assignees

• Bloom Energy Corp

Inventors

• Weingaertner David
• Gottmann Matthias
• Krishnadass Jayakumar
• Karuppaiah Chockkalingam
• Ballantine Arne
• Venkataramaman Swaminathan
• Perry Martin
• Fisher John
• Young Greg

Classifications

• H01M8/0681

  Reactant purification by the use of electrochemical cells · CPC title

• H01M8/0668

  Removal of carbon monoxide or carbon dioxide · CPC title

• H01M8/0662 Primary

  Treatment of gaseous reactants or gaseous residues, e.g. cleaning · CPC title

• H01M8/04097 Primary

  with recycling of the reactants (H01M8/04119, H01M8/04104 take precedence) · CPC title

• H01M8/04022

  Heating by combustion · CPC title