METHOD AND APPARATUS FOR INERTIZING AN OXYGEN-CONTAINING GAS

Abstract

The invention relates to a method for inertizing an oxygen-containing first gas present in a protective housing (4) surrounding a fuel cell (1), wherein a prescribed amount of a hydrogen-containing second gas is introduced into the protective housing (4) and at least part of the oxygen present in the first gas is reduced by cold combustion.

Claims

1. A method for inertizing an oxygen-containing first gas present in a protective housing surrounding a fuel cell, wherein a prescribed amount of a hydrogen-containing second gas is introduced into the protective housing and at least part of the oxygen present in the first gas is reduced by cold combustion.

2. The method according to claim 1, wherein the second gas is taken from a reactor (R1) which is connected to the fuel cell and is located upstream of the fuel cell.

3. The method according to claim 1, wherein a flushing gas or an anode exhaust gas from the fuel cell is used as second gas.

4. The method according to claim 1, wherein a catalyst is used for carrying out the cold combustion.

5. The method according to claim 4, wherein said catalyst is a platinum sponge.

6. The method according to claim 1, wherein the oxygen content of the first gas or the oxygen content of a gas mixture of the first and second gas present in the protective housing is measured and the prescribed amount of the second gas to be introduced is determined therefrom.

7. The method according to claim 1, wherein the hydrogen content of a gas mixture of the first and second gas present in the protective housing is measured and the introduction of the second gas is stopped when hydrogen is detected.

8. The method according to claim 1, wherein the amount and composition of the second gas are set so that a pressure in the protective housing is kept in a prescribed range.

9. The method according to claim 8, wherein the second gas is produced by mixing a hydrogen-containing gas having a hydrogen content of more than 66.67% by volume of H.sub.2 with a further hydrogen-containing gas having a hydrogen content of less than 66.67% by volume of H.sub.2 in such a way that the second gas contains a proportion of hydrogen of from 60 to 70% by volume of H.sub.2.

10. An apparatus for inertizing an oxygen-containing first gas present in a protective housing surrounding a fuel cell, wherein a controllable gas feed device for a hydrogen-containing second gas into the protective housing is provided, so that at least part of the oxygen present in the first gas can be reduced by cold combustion.

11. The apparatus according to claim 10, wherein a reactor (R1) which is connected to the fuel cell and is located upstream of the fuel cell has a first gas offtake device for the second gas which is connected to the gas feed device.

12. The apparatus according to claim 10, wherein a second gas offtake device is provided for a flushing gas or an anode exhaust gas at the outlet of the fuel cell and is connected to the gas feed device.

13. The apparatus according to claim 10, wherein a catalyst for carrying out the cold combustion is provided at the outlet of the gas feed device.

14. The apparatus according to claim 13, wherein said catalyst is a platinum sponge.

15. The apparatus according to claim 10, comprising a first sensor for measuring the oxygen content of the first gas or the oxygen content of a gas mixture of the first and second gas present in the protective housing, which transmits a first signal to a control unit for controlling the prescribed amount of the second gas to be introduced.

16. The apparatus according to claim 10, comprising a second sensor for measuring the hydrogen content of a gas mixture of the first and second gas present in the protective housing, which transmits a second signal to a control unit for controlling stopping of the introduction of the second gas.

17. The apparatus according to claim 10, comprising a pressure sensor in the protective housing, which transmits a third signal to a control unit which can control the amount and composition of the second gas in such a way that the pressure in the protective housing is kept in a prescribed range.

18. The apparatus according to claim 10, which comprises a gas mixing unit for producing the second gas, wherein a hydrogen-containing gas having a hydrogen content of more than 66.67% by volume of H.sub.2 is mixed with a further hydrogen-containing gas having a hydrogen content of less than 66.67% by volume of H.sub.2 in such a way that the second gas contains a proportion of hydrogen of from 60 to 70% by volume of H.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of the present invention are illustrated in more detail below with reference to the accompanying drawings in which:

[0033] FIG. 1 shows an apparatus in accordance with the present invention having a first gas offtake device; and

[0034] FIG. 2 shows an apparatus in accordance with the present invention having a second gas offtake device.

DETAILED DESCRIPTION OF THE INVENTION

[0035] FIG. 1 schematically shows a fuel cell 1 having a gas inlet 2 and a gas outlet 3. The fuel cell 1 is surrounded by a protective housing 4. The fuel cell 1 is connected upstream to a reactor R1. Between the reactor R1 and the fuel cell 1, there is a first offtake device 5a which is connected to a controllable gas feed device 6. A catalyst 8 is advantageously located at the outlet of the gas feed device 6.

[0036] The controllable gas feed device 6 can be controlled by means of a control device 7. A first sensor 9a and/or a second sensor 9b by means of which the hydrogen content and/or oxygen content in the protective housing 4 is measured is advantageously arranged in the protective housing 4. Corresponding signals are transmitted to the control device 7. A hydrocarbon is introduced via the gas inlet 2 into the reactor R1. In the reactor R1, which is in particular a reformer, a hydrogen-containing second gas is produced. Part of the second gas is taken off at the first offtake device 5a between the first reactor R1 and the fuel cell 1 and is conveyed via the controllable gas feed device 6 into the protective housing 4. Here, the amount in particular but also a flow rate of the second gas is controlled. The control of the gas feed device 6 ensures that cold combustion occurs. In particular, it is also ensured by means of the gas feed device 6 that no gas flows back from the protective housing 4 into the first offtake device 5a. A catalyst 8 is advantageously installed at the outlet of the gas feed device 6 so that the cold combustion proceeds over the catalyst 8. The first sensor 9a and/or the second sensor 9b determines the oxygen content and/or hydrogen content in the protective housing 4. The first sensor 9a transmits a first signal to the control 7 of the gas feed device 6 and the second sensor 9b correspondingly transmits a second signal.

[0037] FIG. 2 shows an apparatus having a second gas offtake device 5b which is provided at the outlet of the fuel cell 1. This second gas offtake device 5b is again connected to a controllable gas feed device 6 which introduces the hydrogen-containing second gas via a catalyst 8 into the protective housing 4. Hydrogen and oxygen content in the protective housing 4 can be determined by means of a first sensor 9a and a second sensor 9b. The first sensor 9a and/or the second sensor 9b transmit first and/or second signals to the control unit 7 which regulates the gas feed device 6. The flushing gas or the hydrogen-containing anode exhaust gas is taken off from the fuel cell 1 by means of the second gas offtake device 5b and conveyed via the controllable gas feed device 6 into the protective housing 4.

LIST OF REFERENCE SYMBOLS

[0038] 1 Fuel cell [0039] 2 Gas inlet [0040] 3 Gas outlet [0041] 4 Protective housing [0042] 5a First offtake device [0043] 5b Second offtake device [0044] 6 Gas feed device [0045] 7 Control unit [0046] 8 Catalyst [0047] 9a First sensor [0048] 9b Second sensor [0049] R1 Reactor