METHOD FOR OPERATING A FUEL CELL SYSTEM, AND FUEL CELL SYSTEM

Abstract

The invention relates to a method for operating a fuel cell system in which at least one fuel cell (1) is supplied with hydrogen via an anode path (2) and with oxygen via a cathode path, and in which anode exhaust gas exiting the fuel cell (1) is recirculated via a recirculation path (3), wherein steam contained in the anode exhaust gas is adsorbed by means of a zeolite container (4). According to the invention, the following steps are carried out in order to regenerate the zeolite container (4): a) separating the zeolite container (4) from the recirculation path (3) by closing at least one shut-off valve (5, 6) and/or switching a directional control valve (7), b) heating the zeolite container (4) by means of an electric heating device (8) such that previously adsorbed water is desorbed, and c) removing the desorbed water from the system by switching the directional control valve (7) again and/or by opening at least one flushing valve (9, 10). The invention additionally relates to a fuel cell system which is suitable for carrying out the method.

Description

Claims

1. A method for operating a fuel cell system, in which at least one fuel cell (1) is supplied with hydrogen via an anode path (2) and oxygen via a cathode path, and in which anode exhaust gas escaping from the fuel cell (1) is recirculated via a recirculation path (3), wherein water vapor contained in the anode exhaust gas is adsorbed by means of a zeolite reservoir (4), wherein, for the regeneration of the zeolite reservoir (4), the following steps are carried out: a) separating the zeolite reservoir (4) from the recirculation path (3) by closing at least one shut-off valve (5, 6), and/or by switching a directional control valve (7), or both,b) heating the zeolite reservoir (4) by means of an electrical heating device (8), so that previously adsorbed water is desorbed, andc) removing desorbed water from the system by switching the directional control valve (7) again, and/or by opening at least one flushing valve (9, 10), or both.

2. The method according to claim 1, herein step a) is initiated when a maximum hydrogen concentration (XH2,max), and/or a maximum hydrogen partial pressure (pH2) is not reached in the recirculation path (3), or both .

3. The methodMethed according to claim 1, in step b), the zeolite reservoir (4) is heated to a temperature of about 250° C., at least one heating cartridge integrated into the zeolite reservoir (4) is used as an electrical heating device (8) for heating the zeolite reservoir (4), or both.

4. The methodMethed according to claim 1wherein the pressure and/or the temperature in the zeolite reservoir (4) are measured, and, from the measured values, the amount of water desorbed in the zeolite reservoir (4) is deduced.

5. The method according to claim 1, wherein the heating of the zeolite reservoir (4) is ended when a prespecified maximum pressure and/or temperature limit value is reached in the zeolite reservoir (4).

6. The methodMethed according to claim 1wherein, before step c) is initiated, preferably a check is made as to whether dilution conditions are present for opening a flushing valve (9, 10).

7. The methodMethed according to claim 1wherein, in step c), desorbed water is introduced into a cathode exhaust gas path or discharged to the environment via the directional control valve (7) and/or the at least one flushing valve (9, 10).

8. The method according to claim 1 wherein, in step c), at least one shut-off valve (5, 6) is opened so that desorbed water from the zeolite reservoir (4) is routed to the at least one flushing valve (9, 10).

9. The methodMethed according to claim 1wherein steps a) through c) are repeated wherein a first flushing valve (9) is opened during the first flushing, and a second flushing valve (10) is opened during repeated flushing.

10. A fuel cell system with at least one fuel cell (1), configured to be supplied with hydrogen via an anode path (2) and with oxygen via a cathode path, comprising a recirculation path (3) via which anode exhaust gas escaping from the fuel cell (1) can is recirculated, and also a zeolite reservoir (4) by means of which water vapor contained in the anode exhaust gas is adsorbed, wherein the zeolite reservoir (4) is connected or disconnected via at least one shut-off valve (5, 6) and/or a directional control valve (7).

11. The fuel cell system according to claim 10, wherein an electrical heating device (8), is integrated into the zeolite reservoir (4), so that the zeolite reservoir (4) can be heated for the desorption of water.

12. The fuel cell system according to claim 1, wherein the zeolite reservoir (4) is connected to a cathode exhaust gas path and/or to the environment via the directional control valve (7) and/or at least one flushing valve (9, 10), so that desorbed water from the zeolite reservoir (4) can be introduced into the cathode exhaust gas path or be discharged to the environment.