Method for operating a fuel cell system, control device

Abstract

The invention relates to a method for operating a fuel cell system comprising a fuel cell stack (1), in which an anode gas comprising fresh and recycled hydrogen is supplied to the anode (2) of the fuel cell stack (1) via an anode circuit (3), and liquid water contained in the anode gas is separated using a water separator (4) integrated in the anode circuit (3), collected in a container (5) and removed from the system by temporarily opening a drain valve (6). According to the invention, to detect whether the container (5) is full, the actual temperature of the anode gas at the inlet region (7) of the anode (2) of the fuel cell stack (1) is compared with a target temperature, and if it falls below the target temperature, the container (5) is assumed to be full and the drain valve (6) is opened. The invention further relates to a control device for carrying out the method or individual method steps.

Claims

1. An anode gas containing fresh hydrogen and recycled hydrogen is supplied to the anode (2) of a fuel cell stack (1) via an anode circuit (3), and liquid water contained in the anode gas is separated using a water separator (4) incorporated in the anode circuit (3), collected in a container (5), and removed from the fuel cell system by temporarily opening a drain valve (6). In a method of operating the fuel cell system comprising the fuel cell stack (1), in order to detect that the container (5) is full, the actual temperature of the anode gas in the inlet region (7) of the anode (2) of the fuel cell stack (1) is compared with a target temperature. If the actual temperature is lower than the target temperature, it is presumed that the container (5) is full, and the drain valve (6) is opened. The method is characterized in that the target temperature is calculated in advance, taking into account the composition of the anode gas.

2. The method according to claim 1, characterized in that the actual temperature of the anode gas in the inlet region of the anode (2) of the fuel cell stack (1) is measured using a temperature sensor.

3. The method according to claim 1 or 2, characterized in that when the operating conditions are constant, all events are regarded as having the same weight when calculating the target temperature.

4. Before opening the drain valve (6), a validity check is performed to examine whether the temperature below the target temperature is due to at least one other factor affecting the temperature of the anode gas in the inlet region (7) of the anode (2). The method according to any one of claims 1 to 3.

5. The method according to claim 4, characterized in that the at least one other factor is the external temperature.

6. After the drain valve (6) is closed, a validity check is performed, the current actual temperature of the anode gas in the inlet region (7) of the anode (2) is measured, and compared with the actual temperature before opening the drain valve (6). The method according to any one of claims 1 to 5.

7. The method according to any one of claims 1 to 6, characterized in that the relative humidity of the anode gas in the inlet region of the anode is estimated from the actual temperature, and measures for adjusting the humidity are started as necessary. The method according to claim 7, characterized in that, as the measure for adjusting the humidity, the anode gas is heated and / or the operating point is changed.

9. A control device configured to execute the steps of the method according to any one of claims 1 to 8.

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