Method for generating a gas which may be used for startup and shutdown of a fuel cell

1. A method for startup and shutdown of a fuel cell using a reducing gas generator, comprising:

receiving air into a reducing gas generator air intake;

generating a low oxygen (O 2 ) content oxidant stream using at least in part air received from the air intake;

initiating flow of a hydrocarbon fuel stream in the reducing gas generator;

combining the hydrocarbon fuel stream with the low O 2 content oxidant stream to yield a feed mixture;

directing the feed mixture to a catalyst;

catalytically converting the feed mixture into a reducing gas;

directing the reducing gas to at least one of an anode and a reformer of the fuel cell; and

initiating one of:

a transition of the fuel cell into a power production mode; and

a transition of the fuel cell out of the power production mode.

2. The method of claim 1 , wherein said transition of the fuel cell into the power production mode includes supplying flows of a primary fuel and a primary oxidant to the fuel cell; and wherein said transition of the fuel cell out of the power production mode includes terminating the flows of the primary fuel and the primary oxidant to the fuel cell.

3. The method of claim 1 , wherein said directing the reducing gas to the anode of the fuel cell includes directing the reducing gas to the anode via the reformer.

4. The method of claim 1 , further comprising generating a nitrogen-rich stream from the air received from the air intake, the nitrogen-rich stream forming at least a part of the low oxygen (O 2 ) content oxidant stream.

5. The method of claim 1 , the method further comprising maintaining a selected control temperature by independently varying both the O 2 content of the oxidant stream and the oxidant/fuel ratio of the feed mixture.

6. The method of claim 5 , further comprising sensing the control temperature.

7. The method of claim 6 , further comprising controlling the selected control temperature based on the sensed control temperature.

8. The method of claim 5 , further comprising sensing the O 2 content in at least one of the oxidant stream and the feed mixture.

9. The method of claim 8 , further comprising controlling the selected control temperature based on the sensed O 2 content.

10. The method of claim 5 , further comprising sensing a combustibles content in the reducing gas.

11. The method of claim 10 , further comprising controlling the selected control temperature based on the sensed combustibles content.

12. The method of claim 5 , further comprising controlling a flow rate of the feed mixture while performing said maintaining the selected control temperature by varying both the O 2 content of the oxidant stream and the oxidant/fuel ratio of the feed mixture.

13. The method of claim 1 , further comprising selectively varying a combustibles content of the reducing gas while maintaining a selected control temperature by independently varying both the O 2 content of the oxidant stream and the oxidant/fuel ratio of the feed mixture.

14. The method of claim 13 , further comprising sensing a control temperature.

15. The method of claim 14 , further comprising selectively varying the combustibles content of the reducing gas while maintaining the selected control temperature based on the sensed control temperature.

16. The method of claim 13 , further comprising sensing the O 2 content in at least one of the oxidant and the feed mixture.

17. The method of claim 16 , further comprising selectively varying the combustibles content of the reducing gas while maintaining the selected control temperature based on the sensed O 2 content.

18. The method of claim 13 , further comprising sensing the combustibles content in the reducing gas.

19. The method of claim 18 , further comprising selectively varying the combustibles content of the reducing gas while maintaining the selected control temperature based on the sensed combustibles content.

20. The method of claim 13 , further comprising controlling a flow rate of the feed mixture while performing said selectively varying the combustibles content of the reducing gas while maintaining the selected control temperature.

21. The method of claim 1 , wherein the reducing gas is initially produced as a safe gas directed to the fuel cell during the transition of the fuel cell into the power production mode, further comprising increasing the reducing strength of the reducing gas by increasing the combustibles content of the reducing gas.

22. The method of claim 1 , further comprising:

heating at least a portion of the feed mixture;

directing the heated feed mixture to the catalyst; and

heating the catalyst using the heated feed mixture.

23. The method of claim 22 , further comprising:

maintaining a surface at a preheat temperature one of at and above a catalyst light-off temperature of the feed mixture; and

directing the at least a portion of the feed mixture across the surface in order to perform said heating.

24. The method of claim 23 , further comprising preparing for a shutdown of the fuel cell by maintaining the surface at the preheat temperature while the fuel cell is operating in the power production mode.

25. The method of claim 1 , further comprising heating the catalyst to a preheat temperature configured for catalytic auto-ignition of the feed mixture prior to said directing the feed mixture to the catalyst.

26. The method of claim 1 , further comprising heating at least a portion of the feed mixture prior to said directing the feed mixture to the catalyst.

27. The method of claim 1 , further comprising:

generating a nitrogen-rich stream from the air received from the air intake; and

directing at least some of the nitrogen-rich stream to purge a component associated with a fuel cell.

28. The method of claim 1 , wherein the oxidant stream includes an inert gas selected from the group consisting of nitrogen, argon and helium.

29. A method for shutting down a fuel cell, comprising:

receiving a command to shut down the fuel cell from the power production mode;

receiving air from an air intake;

generating a nitrogen-rich gas stream by extracting oxygen (O 2 ) from the air received from the air intake;

initiating flow of a hydrocarbon fuel stream in response to the command;

combining the hydrocarbon fuel stream with the nitrogen-rich gas stream to yield a feed mixture;

directing the feed mixture to the at least one of a heater, a catalyst and an inlet to the catalyst, wherein the at least one of the heater, catalyst and inlet to the catalyst are heated to a preheat temperature selected for catalytic auto-ignition of the feed mixture;

converting the feed mixture into a reducing gas using the catalyst; and

directing the reducing gas to at least one of an anode and a reformer of the fuel cell.

30. The method of claim 29 , further comprising maintaining the at least one of the heater, the catalyst and the inlet to the catalyst at the preheat temperature selected for catalytic auto-ignition of the feed mixture during fuel cell operation in power production mode prior to receiving the command to shut down the fuel cell.