RECIRCULATION FUEL CELL

Abstract

A recirculation fuel cell device, which can be utilized on a submarine, may include a fuel cell with an anode side and a cathode side, wherein both the anode and cathode sides have input and output sides. The device may include a first inlet for oxygen and a second inlet for hydrogen. The device may further include a cathode-side connection between the output side of the cathode side and the input side of the cathode side, and an anode-side connection between the output side of the anode side and the input side of the anode side. A water separator may be disposed in the cathode-side connection, and a gas discharge valve for a continuous release of process gases may be disposed on the output side of the cathode side of the fuel cell. Operation of the device may involve recirculating an anode gas stream in its entirety.

Claims

1.-20. (canceled)

21. A recirculation fuel cell device comprising: a fuel cell having an anode side and a cathode side, wherein the anode side has an input side and an output side, wherein the cathode side has an input side and an output side; a first inlet for oxygen connected to the input side of the cathode side of the fuel cell; a second inlet for hydrogen connected to the input side of the anode side of the fuel cell; a cathode-side connection between the output side of the cathode side of the fuel cell and the input side of the cathode side of the fuel cell; an anode-side connection between the output side of the anode side of the fuel cell and the input side of the anode side of the fuel cell; a first water separator disposed in the cathode-side connection; and a gas discharge valve disposed on the output side of the cathode side of the fuel cell, the gas discharge valve for a continuous release of process gases.

22. The recirculation fuel cell device of claim 21 being configured to recirculate anode gas in its entirety leaving from the output side of the anode side of the fuel cell.

23. The recirculation fuel cell device of claim 21 wherein the gas discharge valve is a throttle valve.

24. The recirculation fuel cell device of claim 23 wherein the gas discharge valve is configured to be regulated to adjust an inert gas concentration.

25. The recirculation fuel cell device of claim 21 further comprising a first oxygen sensor that detects an oxygen concentration in surrounding air.

26. The recirculation fuel cell device of claim 21 further comprising a first oxygen sensor that detects an oxygen concentration in surrounding air, wherein the gas discharge valve is configured to be regulated to adjust an inert gas concentration based on the oxygen concentration in the surrounding air as detected by the first oxygen sensor.

27. The recirculation fuel cell device of claim 21 further comprising: a first oxygen sensor that detects an oxygen concentration in surrounding air; and a second oxygen sensor that detects an oxygen concentration at the output side of the cathode side of the fuel cell.

28. The recirculation fuel cell device of claim 21 further comprising a first humidifier connected to the first inlet for oxygen.

29. The recirculation fuel cell device of claim 22 further comprising a second humidifier connected to the second inlet for hydrogen.

30. A method for operating a recirculation fuel cell device, the method comprising: recirculating cathode gas in a cathode gas stream; continuously removing a portion of the cathode gas stream from recirculation at an output side of a cathode side of the recirculation fuel cell device; releasing the removed portion of the cathode gas stream to surrounding air; and recirculating anode gas in an anode gas stream in its entirety.

31. The method of claim 30 further comprising regulating an inert gas concentration by discharging gas through a gas discharge valve of the recirculation fuel cell device.

32. The method of claim 31 further comprising regulating an amount of oxygen released by the discharge of gas through the gas discharge valve such that an oxygen concentration in the surrounding air is kept approximately constant.

33. The method of claim 30 wherein through the release of the removed portion of the cathode gas stream an oxygen concentration in the surrounding air does not exceed 25 mol %.

34. The method of claim 30 further comprising increasing an inert gas concentration at the output side of the cathode side of the recirculation fuel cell device to reduce an amount of oxygen released with the removed portion of the cathode gas stream.

35. The method of claim 30 further comprising adjusting an inert gas concentration at the output side of the cathode side of the recirculation fuel cell device to 40 to 70 mol %.

36. The method of claim 30 wherein an amount of inert gas that is removed from recirculation with the removed portion of the cathode gas stream at the output side of the cathode side of the recirculation fuel cell device and released to the surrounding air is equal to an amount of inert gas that is supplied to the recirculation fuel cell device via an oxygen inlet.

37. A submarine that includes a recirculation fuel cell device comprising: a fuel cell having an anode side and a cathode side, wherein the anode side has an input side and an output side, wherein the cathode side has an input side and an output side; a first inlet for oxygen connected to the input side of the cathode side of the fuel cell; a second inlet for hydrogen connected to the input side of the anode side of the fuel cell; a cathode-side connection between the output side of the cathode side of the fuel cell and the input side of the cathode side of the fuel cell; an anode-side connection between the output side of the anode side of the fuel cell and the input side of the anode side of the fuel cell; a first water separator disposed in the cathode-side connection; and a gas discharge valve disposed on the output side of the cathode side of the fuel cell, the gas discharge valve for a continuous release of process gases.

38. The submarine of claim 37 wherein the recirculation fuel cell device provides breathing gases for an air supply to a crew of the submarine via the gas discharge valve.

39. The submarine of claim 37 wherein the recirculation fuel cell device is operated by recirculating cathode gas in a cathode gas stream; continuously removing a portion of the cathode gas stream from recirculation at the output side of the cathode side of the fuel cell; releasing the removed portion of the cathode gas stream to surrounding air; and recirculating anode gas in an anode gas stream in its entirety.

40. The submarine of claim 39 wherein an amount of oxygen released by the release of the removed portion of the cathode gas stream is adjusted so that the amount of oxygen released corresponds to or is less than an amount of oxygen consumed inside the submarine.

Description

[0046] The recirculation fuel cell device in accordance with the invention is described in more detail below by reference to an embodiment illustrated in the drawing.

[0047] FIG. 1 Schematic diagram of a recirculation fuel cell device

[0048] FIG. 1 shows an example of a recirculation fuel cell device in schematic form. The recirculation fuel cell device comprises a fuel cell 10 having a cathode side 11 and an anode side 12. The reduction of O.sub.2 to O.sup.2 takes place on the cathode side 11, while the oxidation of H.sub.2 to H.sup.+ takes place on the anode side 12. The cathode gas leaving from the cathode side 11 of the fuel cell 10 is recirculated via a first water separator 21 and a compressor 31. The anode gas leaving from the anode side 12 of the fuel cell 10 is recirculated via a second water separator 22 and a compressor 32. A portion of the cathode gas stream is released to the surrounding air continuously or cyclically via a gas discharge valve 15. Water can be removed from the circuit from the first water separator 21 and the second water separator 22 via a water outlet 85.

[0049] For the supply of new reactants, the recirculation fuel cell device has a hydrogen tank 60 and an oxygen tank 70, preferably for liquid oxygen. The oxygen is introduced into the cathode circuit via a first humidifier 51, the hydrogen into the anode circuit via a second humidifier 52. The first humidifier 51 and the second humidifier 52 preferably comprise a water-permeable membrane, preferably made of a sulfonated tetrafluoroethylene polymer, for example Nafion (DuPont) or Flemion (Asahi). The first humidifier 51 is supplied with water separated out in the first water separator 21 via a compressor 41 and a heat exchanger 43. The second humidifier 52 is supplied with water separated out in the second water separator 22 via a compressor 42 and a heat exchanger 44. All other combinations for supplying the humidifiers with water separated out in the water separators are also conceivable of course, in particular that the first humidifier 51 and the second humidifier 52 are supplied with water separated out in the first water separator 21 via the compressor 41 and the heat exchanger 43.

[0050] The heat exchangers 43, 44 are preferably operated with cooling water from the fuel cell 10. This embodiment is particularly preferred because the cooling water leaves the fuel cell 10 with the highest temperature, which is at the output side of the fuel cell 10. The water and hence the oxygen or hydrogen introduced with the water are thus already preheated to the correct temperature. The cooling water is adjusted to the temperature prevailing at the input side of the fuel cell 10. This means that no active regulation is required, as the system regulates itself passively.

[0051] To start the fuel cell, inert gas can be introduced into the anode gas circuit and the cathode gas circuit via inert gas feeders 80, such that the desired conditions are set.

REFERENCE SIGNS

[0052] 10 Fuel cell [0053] 11 Cathode side [0054] 12 Anode side [0055] 15 Gas discharge valve [0056] 21 First water separator [0057] 22 Second water separator [0058] 31 Compressor [0059] 32 Compressor [0060] 41 Compressor [0061] 42 Compressor [0062] 43 Heat exchanger [0063] 44 Heat exchanger [0064] 51 First humidifier [0065] 52 Second humidifier [0066] 60 Hydrogen tank [0067] 70 Oxygen tank [0068] 75 Superheater [0069] 80 Inert gas feeder [0070] 85 Water outlet