Shared variable-based fuel cell system control

• US 20060024540A1
• Filed: 07/29/2004
• Published: 02/02/2006
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: DCNS SA (Government of France)
• Original Assignee: DCNS SA (Government of France)
• Inventors: Scharf, Mesa, LaVen, Arne
• Granted Patent: US 8,277,997 B2
• Time in Patent Office: Days
• US Class Current: 429/423
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04328 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04731 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04776 at auxiliary devices, e.g. reformer, compressor, burner
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/0618 Reforming processes, e.g. autothermal, partial oxidation or steam reforming
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Fuel cell systems and methods for controlling the operation of fuel cell assemblies included therein. In some embodiments, the fuel cell assemblies include a fuel processor and a fuel cell stack, and the fuel cell system includes a control system that controls the operation thereof based upon at least one variable associated therewith. In some embodiments, the variable is associated with the hydrogen (or other product) stream from the fuel processor. In some embodiments, the variable is the pressure of this stream. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within one or more threshold values. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within selected threshold values and to maintain the fuel cell stack'"'"'s output voltage above a selected threshold.

Claims

1. A fuel cell system, comprising:

a fuel cell assembly including a fuel source and a fuel cell stack adapted to receive oxidant and to receive a fuel stream from the fuel source and to produce electrical power therefrom, wherein the fuel cell assembly includes a plurality of components having respective functions, the components being adapted to operate in a manner that controls the value of a common variable associated with the fuel stream; and

a control system adapted to control selectively at least the rate of delivery of the fuel stream to the fuel cell stack and the rate of production of electrical power responsive at least in part to the variable.

2. The fuel cell system of claim 1, wherein the variable is the pressure of the fuel stream.

3. The fuel cell system of claim 2, wherein the control system is adapted to control the rate of delivery of the fuel stream to the fuel cell stack and the rate of consumption of the fuel stream by the fuel cell stack to maintain the pressure of the fuel stream between first and second threshold values.

4. The fuel cell system of claim 1, wherein the fuel source includes a fuel processor adapted to produce the fuel stream from at least one feedstock.

5. The fuel cell system of claim 4, wherein the control system is adapted to control the rate of production of the fuel stream and the rate of consumption of the fuel stream by the fuel cell stack to maintain the pressure of the fuel stream between first and second threshold values.

6. The fuel cell system of claim 4, wherein the fuel stream is at least substantially comprised of hydrogen gas.

7. The fuel cell system of claim 6, wherein the fuel processor is adapted to produce the fuel stream by reforming water and at least one carbon-containing feedstock.

8. The fuel cell system of claim 6, wherein the fuel source further includes at least one separation assembly adapted to reduce the concentration of at least one impurity in the fuel stream.

9. The fuel cell system of claim 1, wherein the control system is adapted to control the consumption of the fuel stream by the fuel cell stack by controlling the electrical power produced by the fuel cell stack.

10. The fuel cell system of claim 9, wherein the fuel cell stack is adapted to produce the electrical power at a voltage, and the control system is further adapted to control consumption of the fuel stream by the fuel cell stack to maintain the voltage above a threshold voltage.

11. The fuel cell system of claim 4, wherein the control system is adapted to control consumption of the at least one feedstock by the fuel processor based on the pressure of the fuel stream.

12. The fuel cell system of claim 11, wherein the control system is further adapted to control consumption of the fuel stream by the fuel cell stack based on the pressure of the fuel stream.

13. The fuel cell system of claim 1, wherein the fuel source includes at least one hydrogen-storage device.

14. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 3;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

15. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 2;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

16. An energy-producing and consuming assembly comprising:

a fuel cell system according to claim 1;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

17. A fuel cell system, comprising:

a fuel processing assembly adapted to produce a fuel stream from at least one feedstock;

a fuel cell stack adapted to receive an oxidant and at least a portion of the fuel stream and to produce electrical power therefrom, wherein the fuel stream has a pressure dependent upon the rate of production of the fuel stream and the rate of production of electrical power; and

a control system adapted to detect the pressure of the fuel stream, to control production of the fuel stream by the fuel processing assembly to maintain the pressure of the fuel stream below a first threshold, and to control production of electrical power by the fuel cell stack to maintain the pressure of the fuel stream above a second threshold.

18. The fuel cell system of claim 17, wherein the fuel cell stack is adapted to produce the electrical power at a voltage, and the control system is adapted to control production of electrical power by the fuel cell stack to maintain the voltage above a threshold voltage.

19. The fuel cell system of claim 17, wherein the fuel processing assembly includes at least one hydrogen-storage device.

20. The fuel cell system of claim 17, wherein the fuel stream is at least substantially comprised of hydrogen gas.

21. The fuel cell system of claim 17, wherein the at least one feedstock includes water and at least one carbon-containing feedstock.

22. The fuel cell system of claim 21, wherein the fuel processing assembly is adapted to produce hydrogen gas by steam reforming the water and the at least one carbon-containing feedstock.

23. The fuel cell system of claim 20, wherein the fuel processing assembly further includes at least one separation assembly adapted to selectively reduce the concentration of one or more impurity in the fuel stream.

24. An energy-producing and consuming assembly, comprising:

a fuel cell system according to claim 17;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

25. An energy-producing and consuming assembly, comprising:

a fuel cell system according to claim 18;

and

at least one energy-consuming device adapted to exert an applied load on the fuel cell system.

26. A method for operating a fuel cell system, the method comprising:

producing a fuel stream from one or more feedstocks, such that the fuel stream has a pressure dependent at least in part upon the rate of production of the fuel stream;

receiving at least a portion of the fuel stream by a fuel cell stack;

producing electrical power from the fuel stream received by the fuel cell stack, the fuel stream having a pressure dependent upon the rate of production of electrical power;

detecting the pressure of the fuel stream;

controlling production of the fuel stream in a manner adapted to maintain the pressure of the fuel stream below a first threshold value; and

controlling production of electrical power by the fuel cell stack in a manner adapted to maintain the pressure of the fuel stream above a second threshold value that is less than the first threshold value.

27. The method of claim 26, wherein the producing electrical power includes producing the electrical power at a voltage, and controlling production of electrical power includes controlling production of electrical power in a manner adapted to maintain the voltage above a given voltage.

28. The method of claim 26, wherein the fuel stream is at least substantially comprised of hydrogen gas.

29. The method of claim 26, wherein the producing a fuel stream includes producing the fuel stream by reforming at least a carbon-containing feedstock.

30. The method of claim 29, wherein the fuel stream is at least substantially comprised of hydrogen gas and the producing a fuel stream includes producing the fuel stream by reforming water and at least one carbon-containing feedstock to produce hydrogen gas.

31. The method of claim 29, wherein the producing a fuel stream further includes selectively reducing the concentration of at least one impurity present in the fuel stream.

32. A method of controlling the operation of a fuel cell system, the method comprising:

operating a fuel processor to produce a fuel stream that is at least substantially comprised of hydrogen gas and has a pressure;

operating a fuel cell stack to receive an oxidant stream and at least a portion of the fuel stream and to produce an electrical output therefrom; and

controlling the operation of the fuel processor and the fuel cell stack responsive to the pressure of the fuel stream.

33. The method of claim 32, wherein the controlling further includes controlling the pressure of the fuel stream by controlling a load that is applied to the fuel cell system.