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-11322767-B2
Application number	US-202016840801-A
Country	US
Kind code	B2
Filing date	Apr 6, 2020
Priority date	Apr 12, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

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 one of the first or the second electrochemical hydrogen pump separators;
a second separation conduit that fluidly connects an anode outlet of one of the first or the second electrochemical hydrogen pump separators to an anode inlet of the second pump separator;
an ATO inlet conduit that fluidly connects a cathode outlet of one of the first or the second electrochemical hydrogen pump separators to the anode tail gas oxidizer;
a hydrogen conduit that fluidly connects a cathode outlet of one of the first or the second electrochemical hydrogen pump separators to a fuel inlet of the fuel cell stack; and
a byproduct conduit that fluidly connects an anode outlet of one of the first or the second electrochemical hydrogen pump separator to a carbon dioxide use or storage device;
wherein:
the first separation conduit is configured to provide fuel exhaust generated by the fuel cell stack to one of the first or the second electrochemical hydrogen pump separators;
one of the first or the second electrochemical hydrogen pump separators is configured to separate hydrogen from the provided fuel exhaust; and
the ATO inlet conduit is configured to provide hydrogen output from one of the first or the second electrochemical hydrogen pump separators to the ATO.

2. The fuel cell system of claim 1 , wherein:
the second separation conduit is configured to provide fuel exhaust output from the first electrochemical hydrogen pump separator to the second electrochemical hydrogen pump separator;
the second electrochemical 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 electrochemical 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 electrochemical hydrogen pump separator to the carbon dioxide use or storage device.

3. The fuel cell system of claim 2 , 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.

4. The fuel cell system of claim 1 , 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; and
a mixer operatively connected to the hydrogen conduit and the recycling conduit, the mixer configured to mix hydrogen output by the second hydrogen electrochemical pump separator with fuel exhaust provided by the splitter.

5. The fuel cell system of claim 4 , further comprising:
a water-gas shift reactor operatively connected to the fuel exhaust conduit; and
a Venturi device operatively connected to the recycling conduit.

6. A method of operating the fuel cell system of claim 2 , comprising:
operating the first electrochemical hydrogen pump separator in a constant current mode to control an amount of hydrogen that is provided to the ATO; and
operating the second electrochemical hydrogen pump separator in a constant voltage mode, such that substantially all of the hydrogen is removed from the received fuel exhaust.

7. 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;
a recycling valve configured to selectively control fuel exhaust flow through the recycling conduit and into the ATO inlet conduit; and
at least one feature selected from:
(i) a first feature 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; or

(ii) a second feature 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.

8. The fuel cell system of claim 7 , wherein the at least one feature comprises the first feature.

9. The fuel cell system of claim 7 , wherein the at least one feature comprises the second feature.

10. A method of operating a fuel cell system which comprises:
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;
the method 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.

11. The method of claim 10 , 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.

12. The method of claim 10 , 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.

13. 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 in

Assignees

• Bloom Energy Corp

Inventors

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

Classifications

• H01M8/04291

  Arrangements for managing water in solid electrolyte fuel cell systems (H01M8/04119 takes precedence) · 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

• Y02E60/50

  Fuel cells · CPC title

• H01M8/04022

  Heating by combustion · CPC title