Shutdown method of fuel cell stack and fuel cell system therefor

Patent metadata

Field	Value
Publication number	US-10439239-B2
Application number	US-201514742785-A
Country	US
Kind code	B2
Filing date	Jun 18, 2015
Priority date	Jun 18, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A fuel cell stack, a method of operating a fuel cell stack and a fuel cell system. In one particular form, shutting down the stack upon detection of a leakage of fuel either within the stack or from the stack involves depressurizing and uniform consumption of hydrogen by catalytic consumption in the cathode of all cells. Upon consumption of oxygen in the cathode portion of the stack by chemical reaction, the remaining unreacted nitrogen from the air acts as an inerting fluid. After an indication of reaction cessation is established, at least some of the inerting fluid is conveyed from the cathode portion to the anode portion. One or more of a bleed valve, backpressure valve and bypass valve are manipulated to promote the anode portion depressurization, cathode portion inerting and subsequent conveyance of the inerting fluid to the stack anode portion.

First claim

We claim:

1. A method of shutting down a fuel-cell stack during operation, the method comprising:
detecting a leakage condition within the fuel-cell stack, the fuel-cell stack including a plurality of fuel cells, each fuel cell comprising:
a first portion defining an anode and an anode flowpath coupled to a first source, the first source containing a first reactant,
a second portion defining a cathode and a cathode flowpath coupled to a second source, the second source containing a second reactant, and
a proton-transmissive electrolyte disposed between the first portion and the second portion;

in response to the detecting the leakage condition, reducing pressure in the first portions by shutting off a supply of the first reactant to the anodes, the reducing including manipulating at least one of a first valve and a second valve, the first valve being fluidly disposed in the anode flowpaths and the second valve being fluidly disposed in the cathode flowpaths;
increasing a concentration of an inerting fluid in the cathode flowpaths by manipulating at least one of the first valve and the second valve to promote consumption of at least a portion of the first reactant and the second reactant within the second portions until at least one of a terminal voltage and a first-portion pressure associated with the detected leakage condition is below a respective predetermined level; and
conveying at least a portion of the inerting fluid from the second portions to the first portions.

2. The method of claim 1 , wherein the first valve includes a bleed valve and the second valve includes a backpressure valve.

3. The method of claim 2 , wherein the backpressure valve is closed an amount sufficient to maintain a pressure bias between the first portions and the second portions.

4. The method of claim 3 , further comprising manipulating at least one of the backpressure valve and a bypass valve an amount sufficient to maintain the pressure bias.

5. The method of claim 4 , wherein the pressure bias is between 5 kPa and 10 kPa.

6. The method of claim 1 , wherein the conveying the at least a portion of the inerting fluid from the second portions to the first portions occurs in response to the first-portion pressure being equal to ambient environment temperature.

7. The method of claim 1 , wherein the reducing pressure in the first portions ceases when the first-portion pressure is equal to ambient environment pressure, and wherein the conveying the at least a portion of the inerting fluid from the second portions to the first portions occurs in response to the first-portion pressure being equal to ambient environment temperature.

8. The method of claim 1 , wherein the concentration of the inerting fluid is increased until the terminal voltage is below the respective predetermined level, and the predetermined level of the terminal voltage is 0 volts.

9. The method of claim 1 , wherein the predetermined level of the first-portion pressure is an ambient environment pressure.

10. The method of claim 1 , further comprising closing the first valve and the second valve.

11. The method of claim 10 , further comprising having pressures within the second portions exceed the first-portion pressure associated with the detected leakage condition upon attaining the predetermined level of the terminal voltage.

12. The method of claim 10 , wherein the step of conveying at least a portion of the inerting fluid includes, after the increasing the concentration of the inerting fluid, opening the first valve to a open position while keeping the second valve closed.

13. The method of claim 1 , wherein increase of the concentration of the inerting fluid ceases when a predetermined condition occurs, the predetermined condition being at least one of the first-portion pressure being below an ambient environment pressure and a voltage of the fuel-cell stack being below an amount needed to drive a parasitic load.

14. The method of claim 1 , further comprising increasing, in response to the detecting the leakage condition, an amount of parasitic load on the fuel-cell stack during reducing pressure in the first portions.

15. The method of claim 14 , wherein increasing the amount of the parasitic load comprises increasing flow of a coolant through the fuel-cell stack via a coolant delivery mechanism.

16. The method according to claim 1 , further comprising raising, in response to detecting the leakage condition, stoichiometry of the cathodes including increasing flow of the second reactant.

17. The method according to claim 1 , wherein the reducing pressure in the first portions further includes reducing electric current supplied by the fuel-cell stack to a level that coincides with an amount needed to operate stack ancillary equipment.

18. The method according to claim 1 , wherein the detecting is performed with at least one gas-detection sensor that is placed in fluid communication with the fuel-cell stack, while at least one of the reducing, the increasing, and the conveying is performed at least in part by a controller that is in signal communication with the gas-detection sensor.

19. The method according to claim 1 , wherein the detecting, the reducing, the increasing, and the conveying are performed at least in part by a controller that is in signal communication with the fuel-cell stack through at least one pressure sensor and at least one temperature sensor and without input from a gas-detection sensor.

20. A method of shutting down a fuel-cell stack upon a detection of a leakage condition therein during operation, the method comprising:
providing a plurality of fuel cells, an anode flowpath, and a cathode flowpath within the fuel-cell stack, each of the plurality of fuel cells including:
a first portion including an anode,
a second portion including a cathode, and
a proton-transmissive electrolyte disposed between the first portion and the second portion;

providing a first valve fluidly disposed in the anode flowpath and a second valve fluidly disposed in the cathode flowpath; and
using a controller coupled to the fuel-cell stack, the controller being configured to:
receive at least one signal corresponding to the detection of the leakage condition,
manipulate at least one of the first valve and the second valve to reduce pressure in the first portions, thereby causing a shut-off of a supply of a first reactant to the anodes,

manipulate at least one of the first valve and the second valve to promote consumption of the first reactant and a second reactant within the fuel-cell stack, and
after at least one of a terminal voltage and a first-portion pressure associated with the detected leakage condition is below a respective predetermined level, convey at least a portion of an inerting fluid from the second portions to the first portions,
wherein the anode flowpath fluidly couples the anodes to a first-reactant source containing the first reactant, and wherein the cathode flowpath fluidly couples the cathodes to a second-reactant source containing the second reactant.

Assignees

• Gm Global Tech Operations Llc
• Honda Motor Co Ltd

Inventors

• Sinha Manish
• Cartwright Michael
• Rapaport Pinkhas A
• Uenodai Asao

Classifications

• H01M8/04664

  Failure or abnormal function · CPC title

• H01M8/04223

  during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells · CPC title

• H01M8/0438

  Pressure; Ambient pressure; Flow · CPC title

• H01M8/04679

  of fuel cell stacks · CPC title

• H01M8/04955

  Shut-off or shut-down of fuel cells · CPC title