Apparatus for recirculating anode gas in the anode circuit of a fuel cell system, fuel cell system

Abstract

The device (1) for recirculating anode gas in an anode circuit (11) of a fuel cell system (10) comprises at least one jet pump (2) with a motive nozzle (3) for delivering fresh anode gas, preferably hydrogen, an inlet (4) for the recirculated anode gas, and an outlet (5) for the fresh and recirculated anode gas, in the region of the inlet (4) an actively controllable valve (6) for closing and opening the inlet (4) is arranged, the valve (6) having a magnet arrangement (7) acting on a reciprocating magnet armature (8) and a valve spring (9).Furthermore, a fuel cell system (10) comprising such a device (1) is disclosed.

Description

[Technical field]

[0001] The present invention relates to a device for recirculating anode gas in the anode circuit of a fuel cell system. Furthermore, a fuel cell system comprising the device according to the invention is proposed. [Background technology]

[0002] Fuel cells convert hydrogen and oxygen into electrical energy. For this purpose, hydrogen is supplied to the anode of the fuel cell and oxygen to the cathode. The anode gas leaving the fuel cell usually still contains residual amounts of hydrogen and is therefore recirculated and fed back to the anode. This recirculation can then be triggered actively by a recirculation blower and / or passively by a jet pump.

[0003] If a jet pump is used, its use can prove problematic, since without the activation of the recirculation, additional fresh hydrogen cannot usually be metered in. Also proving problematic is the weakening of the recirculation power of the jet pump in the part load range. To counter this, a second, smaller jet pump can be used, which is designed for the part load range and is arranged in parallel to the first jet pump. If only one jet pump is activated, however, it can occur that the pumping volume of the activated jet pump flows back through the inactive jet pump, and this flow path must be blocked, for example by an integrated check valve. This, however, leads to a pressure loss, which reduces the recirculation power of the activated jet pump. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention is aimed at solving these problems: on the one hand, it is desirable to be able to meter additional fresh hydrogen without activating the recirculation, and on the other hand, it is desirable to prevent a backflow of anode gas through the respective inactive jet pump when jet pumps are connected in parallel, in particular with as few losses as possible. [Means for solving the problem]

[0005] In order to solve these problems, a device is proposed with the features of claim 1. Advantageous developments of the invention can be found in the dependent claims. Furthermore, a fuel cell system is proposed which comprises the device according to the invention.

[0006] The proposed device for recirculating anode gas in the anode circuit of a fuel cell system comprises at least one jet pump with a driven nozzle for delivering fresh anode gas, preferably hydrogen, an inlet for the recirculated anode gas and an outlet for the fresh and recirculated anode gas. In the region of the inlet, an actively controllable valve is arranged in this case, which closes and opens the inlet. The valve comprises a magnet arrangement acting on a reciprocating magnet armature and a valve spring. Effect of the Invention

[0007] By means of an actively controllable valve, the inlet can be closed or blocked, so that the anode gas is not recirculated through the anode circuit. Thus, without recirculation, fresh hydrogen can be fed into the anode circuit via the jet pump, for example for dry operation of the anode circuit. If the device comprises several jet pumps connected in parallel, by means of an actively controllable valve, one jet pump can be suitably deactivated, and a backflow of anode gas through this inactive jet pump can be prevented.

[0008] The actively controllable valve may be configured as a simple low-cost change-over valve that closes or opens the inlet. This is possible because an absolute sealing of the valve is not required to turn off the recirculation, and in addition, no leakage to the outside can occur.

[0009] The magnet assembly of the actively controllable valve can be a simple linear magnetic actuator. Since only small pressure differentials occur in the anode circuit, the valve also requires only small actuator forces, so that the magnet assembly can be designed to be correspondingly compact.

[0010] Preferably, the magnet arrangement of the valve is arranged outside the hydrogen conducting region of the device, in this way a high degree of tightness of the hydrogen conducting region can be achieved, and in addition, possible ignition sources in the hydrogen conducting region are avoided.

[0011] Alternatively or additionally, it is proposed that the direction of action of the magnet assembly extends perpendicular to the main flow direction in the inlet, i.e. the magnetic force generated by the magnet assembly acts on the magnet mover such that it reciprocates perpendicularly to the main flow direction in the inlet, so that the inlet can be closed and opened by a simple reciprocating movement of the magnet mover.

[0012] To close and open the inlet, the magnetic armature is preferably connected to a valve closing element. The magnetic armature and the valve closing element can thereby be manufactured from different materials. Alternatively, it is proposed that the magnetic armature simultaneously forms the valve closing element. In this way, an actively controllable valve can be manufactured even more simply and cost-effectively. To close the inlet, the valve closing element is preferably engageable with a lateral opening of the inlet. That is to say, when the valve is closed, the valve closing element is not only abutted against the wall surface defining the inlet, but also engages in the opening of the wall surface. In this way, the sealing property of the valve can be improved.

[0013] In a further development of the invention, it is proposed that the magnet armature is pierced in the axial direction by at least one pressure compensation opening, which is particularly advantageous when the magnet armature or the valve closing element engages in a lateral opening of the inlet when closing, which is filled with anode gas, thus avoiding that the valve has to be closed against the pressure that builds up in the opening.

[0014] It is further proposed that the magnet armature is at least partially sleeve-shaped in order to accommodate the valve spring, the actively controllable valve can thereby be constructed very compact, particularly in the axial direction, and at the same time the mass of the magnet armature is reduced.

[0015] According to a preferred embodiment of the invention, the magnet assembly has a magnet coil surrounded by an outer pole body, in which a pot-shaped or sleeve-shaped separator made of a non-magnetic material is inserted, through which the magnet mover is guided. The outer pole body increases the magnetic force of the magnet coil. At the same time, the outer pole body protects the magnet coil from external influences. The pot-shaped or sleeve-shaped separator inserted in the magnet coil prevents a magnetic short circuit between the magnet mover and the magnet assembly when the magnet mover is guided. In addition, the separator can seal the area for guiding hydrogen against the magnet assembly.

[0016] Advantageously, the pot-shaped or sleeve-shaped separator element is supported directly or indirectly via a sealing element on the housing outer wall of the device via the annular collar. In this way, the separator element can be used at the same time to seal the hydrogen-guiding area against the outside. By arranging a sealing element, in particular a sealing ring, between the separator element and the housing outer wall, the sealing effect can be optimized. Via the annular collar, the separator element can also be easily attached to the housing outer wall.

[0017] The inlet, in which an actively controllable valve is arranged, preferably opens into the suction chamber of the jet pump, in which a motive nozzle is arranged. By means of the motive nozzle, a driving force can be generated which causes the recirculation of the anode gas. However, if the inlet is closed by the actively controllable valve, the recirculation can be appropriately switched off. The suction chamber is preferably connected to the outlet of the jet pump via a mixing tube and a diffuser. In the suction chamber, the recirculated anode gas and the fresh anode gas join together. In the subsequent mixing tube, the recirculated anode gas and the fresh anode gas are mixed. Preferably, the inlet for the recirculated anode gas opens laterally into the suction chamber, so that the motive nozzle can be arranged coaxially with respect to the mixing tube and the diffuser.

[0018] A regulating valve may be connected upstream of the motive nozzle to allow the use of fresh anode gas as motive medium, or alternatively the motive nozzle may be integrated into the metering valve for fresh anode gas, resulting in a particularly compact assembly with few components.

[0019] Advantageously, the device comprises at least two jet pumps which are connected in parallel and can be activated depending on the load, so that a sufficient recirculation power can be ensured even in the partial load range, and at the same time, during operation of only one jet pump, a backflow of the pumping volume of the activated jet pump through the inactivated jet pump can be prevented by an actively controllable valve arranged in the inlet.

[0020] Since a preferred field of application is fuel cell systems, we further propose a fuel cell system comprising a device according to the invention, which in this case is integrated into the anode circuit of the fuel cell system. By means of the device, the anode gas leaving at least one fuel cell can be recirculated, so that the required fuel amount is reduced. By means of an actively controllable valve arranged in the inlet of the jet pump, the recirculation can be switched off. If the recirculation is caused by several jet pumps connected in parallel, at least one jet pump can be deactivated and a backflow of the anode gas through this jet pump can be actively prevented.

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic longitudinal section view of a first device for recirculating anode gas according to the invention in an operational state with the inlet closed; FIG. [Diagram 2] FIG. 2 is a schematic longitudinal section through the device of FIG. 1 in an operational state with the inlet open; [Diagram 3] FIG. 2 is a schematic longitudinal section view of a second device according to the invention for recirculating anode gas; [Figure 4] FIG. 2 is a schematic diagram of an anode circuit of a fuel cell system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The device 1 according to the invention, shown diagrammatically in FIG. 1, is used for recirculating anode gas in an anode circuit 11 of a fuel cell system 10 (see FIG. 4). For this purpose, the device 1 comprises a jet pump 2, which is or can be integrated into the anode circuit 11 via an inlet 4 and an outlet 5. The jet pump 2 further comprises a motive nozzle 3, which has a regulating valve 24 connected upstream and capable of feeding fresh anode gas into a suction chamber 21 of the jet pump 2. The fresh anode gas is simultaneously used as a driving medium, since when the fresh anode gas is fed by the motive nozzle, a driving force is generated which leads to a recirculation of the anode gas in the anode circuit 11. The recirculated anode gas is introduced into the suction chamber 21 via the inlet 4. The inlet 4 opens laterally into the suction chamber 21, whereas the motive nozzle 3 is arranged coaxially with respect to the mixing tube 22 and the diffuser 23 of the jet pump 2.

[0024] An actively controllable valve 6 is integrated in the inlet 4 and has a magnet arrangement 7 which acts on a reciprocating magnet armature 8. The valve 6 is configured here as a de-energized closed valve, i.e. when the magnet arrangement 7 is not energized, the valve 6 is closed. In this switching position, the inlet 4 is also closed, so that recirculation is switched off. The closing force is generated by a valve spring 9, which is supported for this purpose on the magnet armature 8.

[0025] The magnet arrangement 7 of the valve 6 is arranged externally, i.e. outside the hydrogen-guiding region 12. This facilitates sealing of the hydrogen-guiding region 12 from the outside. Furthermore, the possibility of ignition sources forming in the hydrogen-guiding region 12 is avoided. The magnet arrangement 7 has an outer pole body 15, in which a magnet coil 16 is accommodated. A pot-shaped separator element 17 is inserted in the magnet coil 16, which is made of a non-magnetic material. The pot-shaped separator element 17 serves to guide the magnet mover 8 and at the same time prevents a magnetic short circuit between the magnet mover 8 and the magnet arrangement 7. Furthermore, the separator element 17 performs a sealing function. On the one hand, the separator element 17 separates the hydrogen-guiding region 12 from the magnet arrangement 7. On the other hand, the separator element 17 seals the hydrogen-guiding region 12 from the outside. The separating element 17 has for this purpose an annular flange 18 and is supported via the annular flange 18 on an outer housing wall surface 19 of the device 1. In order to improve the sealing action, a sealing element 20 is provided between the annular flange 18 and the outer housing wall surface 19.

[0026] The magnetic armature 8 of the actively controllable valve 6 here simultaneously forms a valve closing element which, in the closed position, engages in a lateral opening 13 in the inner wall which defines the inlet. In order to prevent a pressure cushion from forming in the opening 13 which would impede the movement of the magnetic armature 8, the magnetic armature 8 has a pressure compensation opening 14. The magnetic armature 8 is formed approximately sleeve-shaped so that it can accommodate the valve spring 9. At its other end, the valve spring 9 is supported on a pot-shaped isolating element 17.

[0027] When the magnet coil 16 of the magnet assembly 7 is energized, a magnetic field is generated, the magnetic force of which moves the magnet mover 8 towards the magnet coil 16. This leads to the opening of the valve 6, so that the inlet 4 is free. In this switching position of the valve 6, the anode gas can be recirculated (see FIG. 2). To switch off the recirculation, the valve 6 must be closed. For this, the energization of the magnet coil 16 is terminated, so that the valve spring 9 returns the magnet mover 8 to its initial position (FIG. 1).

[0028] In Fig. 3, a further device 1 according to the invention for recirculating anode gas can be seen. This further device 1 differs from the device 1 of Figs. 1 and 2 only in the configuration of the valve 6. In Fig. 3, the valve 6 is configured not as a de-energized closed valve, but as a de-energized open valve. The magnetic armature 8 has a slightly different shape for this purpose. In other respects, the valve 6 can be configured similarly to the valve 6 of Figs. 1 and 2.

[0029] The device 1 according to the invention, which is shown exemplarily in Figures 1 to 3, is used in particular in the anode circuit 11 of a fuel cell system 10. This is shown diagrammatically in Figure 4.

[0030] The anode circuit 11 is shown via the anode 25 of a fuel cell 30, which combines hydrogen with oxygen to convert it into electrical energy. Air is used as the oxygen source, and is supplied to the cathode 26 of the fuel cell 30 via a cathode path not further shown in FIG.

[0031] Fresh hydrogen (H2) is fed into the anode circuit 11 via a regulating valve 24 and a jet pump 2. The regulating valve 24 and the jet pump 2 form a device 1 for recirculating anode gas. In the jet pump 2, the fresh anode gas and the recirculated anode gas are therefore mixed. Since the recirculated anode gas becomes enriched with nitrogen (N2) diffusing from the cathode side to the anode side over time, the anode circuit must be purged from time to time. For this purpose, a purge valve 29 is integrated into the anode circuit 11. The purge valve 29 is preceded by a water separator 27 and a drain valve 28, by means of which product water (H2O) arising during the operation of the fuel cell system 10 can be removed from the anode circuit 11.

[0032] The device 1 for recirculating anode gas is connected to an anode circuit 11 via an inlet 4 and an outlet 5. An actively controllable valve 6 is integrated into the inlet 4. Depending on the switching position of the valve 6, the inlet 4 is either open or closed. It is thus also possible to feed fresh anode gas via the jet pump 2 without recirculating the anode gas. By means of the actively controllable valve 6, the recirculation can thereby be switched off. [Explanation of symbols]

[0033] 1. A device for recirculating anode gas in the anode circuit of a fuel cell system 2 Jet pump 3 Driving nozzle 4 entrance 5 exit 6 Valves 7. Magnet configuration group 8. Magnet mover 9 Valve spring 10. Fuel Cell System 11 Anode Circuit 12 Hydrogen Guiding Area 13 Aperture 14 Pressure compensation opening 15 Outer pole body 16 Magnet coil 17 Isolation elements 18 Annular brim 19 Housing outer wall surface 20 Sealing elements 21 Suction chamber 22 Mixing tube 23 Diffuser 24 Regulating valve 25 Anode 26 Cathode 27 Water separator 28 Drain valve 29 Purge valve 30 Fuel Cell

Claims

1. 1. A device (1) for recirculating anode gas in an anode circuit (11) of a fuel cell system (10), comprising at least one jet pump (2) with a motive nozzle (3) for delivering fresh anode gas, preferably hydrogen, an inlet (4) for the recirculated anode gas, and an outlet (5) for the fresh anode gas and the recirculated anode gas, in the region of the inlet (4) an actively controllable valve (6) for closing and opening the inlet (4) is arranged, the valve (6) having a magnet assembly (7) acting on a reciprocating magnet armature (8) and a valve spring (9).

2. 2. The device (1) according to claim 1, characterized in that the magnetic assembly (7) of the valve (6) is arranged outside a hydrogen conducting area (12) of the device (1) and / or the acting direction of the magnetic assembly (7) runs perpendicular to the main flow direction in the inlet (4).

3. 3. The device (1) according to claim 1 or 2, characterized in that the magnetic armature (8) is connected to or forms a valve closing element, which is preferably engageable with a lateral opening (13) of the inlet (4) to close the inlet (4).

4. 4. The device (1) according to claim 1, wherein the magnet armature (8) is pierced in the axial direction by at least one pressure compensation opening (14).

5. 5. The device (1) according to claim 1, wherein the magnetic armature (8) is at least partially sleeve-shaped to accommodate the valve spring (9).

6. 6. The device (1) according to claim 1, characterized in that the magnet assembly (7) has a magnet coil (16) surrounded by an outer pole body (15), in which a pot-shaped or sleeve-shaped separator element (17) made of a non-magnetic material is inserted, and the magnet mover (8) is guided via the separator element (17).

7. 7. The device (1) according to claim 6, characterized in that the pot-shaped or sleeve-shaped separating element (17) is supported via an annular flange (18) on the outer wall surface (19) of the housing of the device (1) directly or indirectly via a sealing element (20).

8. 8. The device (1) according to claim 1, characterized in that the inlet (4) opens into a suction chamber (21) of the jet pump (2), in which the motive nozzle (3) is arranged and / or the suction chamber (21) is connected to the outlet (5) via a mixing tube (22) and a diffuser (23).

9. 9. The device (1) according to claim 1, characterized in that a regulating valve (24) for metering fresh anode gas is connected upstream of the motive nozzle (3) or the motive nozzle (3) is integrated in a metering valve for fresh anode gas.

10. 10. The device (1) according to any one of the preceding claims, characterized in that at least two load-operable jet pumps (2) are connected in parallel.

11. A fuel cell system (10) comprising a device (1) according to any one of claims 1 to 10, said device (1) being integrated into an anode circuit (11) of said fuel cell system (10).

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