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Paramétrages

Paramétrages

1. WO2005065103 - EVACUATION D'EAU SECURISEE D'EMPILEMENTS DE PILES A COMBUSTIBLE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

WHAT I CLAIM IS:

1. A method for purging water or other liquid from one or both of the anode compartment and the cathode of a fuel cell stack, wherein the one or more compartments is connected to a regulated source of hydrogen or of oxygen via a first valve, and to a recycle tank via a second valve, said recycle tank further being connected to a third valve for purging gases and to a fourth valve for purging water or other liquid from the tank,

the method comprising (1) normal fuel cell operation with the first valve and the other valves are closed, (2) an anode purge with the first, third and fourth valves are closed and the second valve is open, (3) a pressurization stage wherein the first and second valves are open and the third and fourth valves are closed and (4) an evacuation stage wherein only the second valve is open and (5) return to the normal stage by opening the first valve again and closing the other valves.

2. The method of claim 1, further comprising a fifth state in which gas is purged from the tank, the fifth state being obtained from the first state by opening the third valve, and ended by closing the third valve, while the first valve is open and the second and fourth valves are closed.

3. The method of claim 2, further comprising a sixth state in which liquid is purged from the tank, the sixth state being obtained from the first state by opening the fourth valve, and ended by closing the fourth valve, while the first valve is open and the second and third valves are closed.

4. The method of claim 1, wherein the system further provides means for limiting the efflux rate of gases from the tank.

5. The method of claim 4 wherein the flow-limiting means is at least one of a prefabricated orifice, a calibrated hole in a barrier, a length of narrow diameter tubing, and a pump.

6. The method of claim 1, wherein the compartment is an anode compartment, wherein anode exhaust gases leaving the tank are forced to mix with a diluting flow of air before being exhausted from the system.

7. The method of claim 6, wherein the diluting flow is sufficient to reduce the hydrogen concentration in the resulting mixed flow to below the lower flammable limit of
hydrogen in air.

8. The method of claim 7, where the diluting flow comprises a cathode exhaust.

9. The method of claim 2, wherein the fifth state is not entered after every cycle of states 1 through 4, but only on demand, by calculation, or by timing.

10. The method of claim 9, wherein the fifth state'is entered on about every fifth cycle on average.

11. The method of claim 9, wherein the fifth state is entered on about every tenth cycle on average.

12. The method of claim 3, wherein the sixth state is not entered after every cycle of states 1 through 4, but only on demand, by calculation, or by timing.

13. The method of claim 12, wherein the sixth state is entered on about every fifth cycle on average.

14. A method for safely purging the anode compartment of a fuel cell stack, the method comprising the steps of:
a) collecting anode exhaust to be purged in a recycle tank downstream of the anode compartment;
b) isolating the recycle tank from the anode compartment;
c) activating a means for causing the escape of anode exhaust gas from the recycle compartment; and
d) mixing the escaping anode exhaust gas with a diluting volume of air, wherein the diluting air is sufficient to reduce the concentration of hydrogen in the mixed stream to below the lower flammable limit of hydrogen in air.

15. The method of claim 14 wherein the dilution is to a level below 1/4* of the lower flammable limit of hydrogen in air.

16. The method of claim 14 wherein the diluting air comprises the cathode exhaust of the fuel cell stack.

17. The method of claim 14 wherein the diluting air comprises air other than the cathode exhaust of the fuel cell stack.

18. The method of claim 14 wherein the escaping anode exhaust gas is passed through a flow-limiting means before it is mixed with diluting air.

19. The method of claim 18 wherein the flow-limiting means is at least one of a
prefabricated orifice, a calibrated hole in a barrier, a length of narrow diameter tubing, and a pump.

20. The method of claim 18 wherein the flow of anode exhaust is further regulated by a valve.

21. An apparatus for purging a fuel cell stack of fluid or gas present in one or both of the anode and cathode compartments, wherein the apparatus comprises a fuel cell stack having an anode compartment and a cathode compartment, and wherein each compartment to be purged is connected to a regulated source of
hydrogen or of oxygen via a first valve, and to a recycle tank via a second valve, said recycle tank further being connected to a third valve for purging gases and to a fourth valve for purging water or other liquid from the tank,

the apparatus further comprising a pressure sensor connected to each compartment to be purged, and a controller to sequence the opening and closing of valves based on input from the pressure sensor, and based on timing or calculation, and optionally based on input from one or more other sensors.

22. The apparatus of claim 21 further comprising a flow-regulating means in a line beyond the third valve for limiting the rate of escape of hydrogen-containing anode exhaust from the recycle tank.

23. The apparatus of claim 21 further comprising means for mixing anode exhaust leaving the third valve with a source of diluting air.

24. The apparatus of claim 23 wherein the dilution is to a level below 174th of the lower flammable limit of hydrogen in air.

25. The apparatus of claim 23 wherein the diluting air comprises the cathode exhaust of the fuel cell stack.

26. The apparatus of claim 23 wherein the diluting air comprises air other than the cathode exhaust of the fuel cell stack.

27. The apparatus of claim 22 wherein the escaping anode exhaust gas is passed through a flow-limiting means before it is mixed with diluting air.

28. The apparatus of claim 22 wherein the flow-limiting means is at least one of a
prefabricated orifice, a calibrated hole in a barrier, a length of narrow diameter tubing, and a pump.

29. The apparatus of claim 21 wherein the controller is constructed and arranged to provide a series of states for purging the one or more fuel cell stack compartments, each state
having a set of valves open and the other valves closed, wherein in a first state only the first valve is open; in a second state only the second valve is open; in a third state the first and second valves are open; in a fourth state only the second valve is open; and the first state follows the fourth state.

30. The apparatus of claim 21 wherein a fifth state is provided by opening the third valve while the second valve and the fourth valve are closed, thereby purging gas from the recycle tank.

31. The apparatus of claim 21 wherein a sixth state is provided by opening the fourth valve while the second valve and the third valve are closed, thereby purging liquid from the recycle tank.

32. The apparatus of claim 20 wherein purging of the recycle tank via the third valve does not occur at every opportunity to do so.

33. The apparatus of claim 23 wherein purging of the recycle tank via the fourth valve does not occur at every opportunity to do so.

34. The apparatus of claim 21 wherein the system further provides means for limiting the efflux rate of gases from the recycle tank.