Fuel cell tower of a fuel cell system having a housing

Abstract

The present invention relates to a fuel cell tower (10) of a fuel cell system having a housing (20), which has a housing space (22), in which at least one fuel cell stack (30) is arranged, wherein the housing (20) has at least one side opening (24), which is closed by means of a side wall (40), wherein at least one compressible compression layer (50) is arranged between the side wall (40), which closes the at least one side opening (24), and the at least one fuel cell stack (30), which compressible compression layer at least in sections contacts the fuel cell stack (30) and an inner side (42) of the side wall (40) in a sealing manner.

Description

[0001] Fuel cell tower of a fuel cell system, comprising a housing

[0002] The present invention relates to a fuel cell tower of a fuel cell system, comprising a housing and a set of fuel cell towers, as well as an assembly method for assembling such a fuel cell tower and a housing for such a fuel cell tower.

[0003] It is generally known that fuel cell systems vary in size depending on the required performance. Care is taken to ensure that the individual components can be assembled, preferably in a modular manner. To provide higher electrical outputs, it is known to equip so-called fuel cell towers with one or more fuel cell stacks in order to provide the desired electrical output from a plurality of fuel cell stacks. To simplify assembly, such fuel cell towers are often provided with a housing so that two or more fuel cell stacks can be arranged within such a housing and electrically connected to one another.The fuel cell tower of such a fuel cell system represents a sub-module of the fuel cell system, which can provide electrical power with two or more fuel cell stacks.

[0004] A disadvantage of the known solutions is that such housings must be relatively complex. For the assembly process of such fuel cell towers, access to the housing space is necessary not only to arrange the fuel cell stacks within the housing space, but also to electrically couple them together in the desired manner for subsequent operation. For this purpose, such housings are typically equipped with side openings to provide access for such assembly steps after the fuel cell stacks have been arranged in the housing space. For the operation of the fuel cell tower, such a side opening must subsequently be closed to ensure safe and gas-tight operation.

[0005] A disadvantage of the known solutions is the considerable effort required to close such side openings. Since fuel cell stacks can often have different shapes and, in addition, significant thermal expansion is to be expected during operation of the fuel cell system due to the high operating temperatures, such a closure option requires a correspondingly high level of effort. Simple plates cannot be used here, so, depending on the actual design of the side opening, a geometric side wall construction specifically designed for this side opening must be provided. This results in custom production, with correspondingly high costs and effort.

[0006] The object of the present invention is to at least partially remedy the disadvantages described above. In particular, the object of the present invention is to provide a cost-effective and simple means of closing a side opening in a housing of a fuel cell system.

[0007] The above object is achieved by a fuel cell tower having the features of claim 1, a housing having the features of claim 12, a set having the features of claim 13, and an assembly method having the features of claim 14. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the fuel cell tower according to the invention naturally also apply in connection with the housing according to the invention and the assembly method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made reciprocally.

[0008] According to the invention, a fuel cell tower is provided as part of a fuel cell system. For this purpose, the fuel cell tower has a housing equipped with a housing interior. At least one fuel cell stack is arranged in this housing interior. The housing is equipped with at least one side opening, which is closed by a side wall. Such a fuel cell tower is characterized in that at least one compressible compression layer is arranged between the side wall, which closes the at least one side opening, and the at least one fuel cell stack. This compression layer is in sealing contact, at least in sections, with the fuel cell stack and also with the inside of the side wall.

[0009] The core concept of the invention is to be able to provide a side wall that can be used as universally as possible. To ensure this, a compression layer is introduced as an additional component. This compression layer is compressible and can therefore adapt to the surrounding components through plastic and / or elastic deformation. By inserting such a compression layer between the side wall and the fuel cell stack, a compressible compensation can be provided, which can be achieved through plastic and / or elastic deformation. In other words, it is now possible to provide the side wall independently of the geometric design and correlation with the at least one fuel cell stack. The desired sealing design within the housing space is ensured by the compression layer.The design of the compression layer, which makes direct or indirect contact via other components, between the fuel cell stack and the inner sides of the sidewall, also ensures a seal for the fuel cell stack's operating gases. Furthermore, it is advantageous to choose a material that does not damage the fuel cell stack, for example, through chemical processes.

[0010] Such a fuel cell tower is designed in particular as a so-called open cathode or (in the case of an SOEC system or electrolysis system) as an open air side. This means that, for example, air, in particular as cathode gas, is introduced into the fuel cell tower laterally, in particular transversely to the stacking direction. Due to the open design of the fuel cell stacks, this operating gas now flows through the individual fuel cell stacks from one side to the other along a flow direction. In this case, it must be ensured that as large a portion of this operating gas as possible is actually forced through the fuel cell stacks. To ensure this, the compression layer according to the invention is arranged in a sealingly contacting manner in the manner mentioned, so that an undesired bypass past the fuel cell stacks is excluded or at least minimized.The side wall is particularly designed such that the fuel cell tower is not damaged and / or deformed during assembly.

[0011] In addition to its sealing function, a compression layer according to the invention is also capable of compensating for geometric inequalities. These geometric inequalities can be due, for example, to differently shaped outer contours of the fuel cell stacks. Operating temperatures of over 650°C, in particular over 800°C, are to be expected for the operation of the fuel cell tower. In particular, due to the fact that there is a difference of almost 1000 degrees Celsius between the switched-off state of the fuel cell tower at room temperature and the aforementioned operating temperature, the compression layer is also capable of compensating for thermal changes in expansion. Such a compression layer can therefore also be referred to as a thermal compensation layer. This is particularly important if no undesired bypass is to be directed past the fuel cell stacks.

[0012] As can be seen from the above explanation, the compensating functionality is now provided by the compression layer. This means that the sidewall can be designed as a universal modular component, since it does not have to take into account different temperature situations, different length changes, or different geometric configurations of the fuel cell stack. In other words, the sidewall can be designed as a standard component and thus provided in a cost-effective and simple manner. An access plate can preferably be provided for this purpose.

[0013] It is advantageous if at least two fuel cell stacks are arranged one above the other in the housing space along a stacking direction. The compressible compression layer is arranged between the side wall, which closes the at least one side opening, and the at least two fuel cell stacks.

[0014] It can be advantageous if, in a fuel cell tower according to the invention, the at least one compression layer extends over the entire or substantially the entire side opening. Such a compression layer can be formed in one piece or in multiple pieces. The functionality of the compression layer is preferably provided over the entire side opening, so that, for example, the side wall is subsequently formed larger than the side opening in order to completely cover the side opening and the compression layer arranged therein. For the assembly process, the compression layer can now be inserted into the side opening, for example in a form-fitting or substantially form-fitting manner. It is also possible for an excess dimension with respect to the side opening to be provided for the compression layer.In such an oversize situation, the compression layer can be pressed into the side openings by the oversize and is then held there by the flexible compressibility until the side opening is covered by the side wall. This can generally be achieved alternatively or additionally via the top side of the fuel cell tower. In this case, the compression layer therefore extends alternatively or additionally over the top side of the fuel cell tower.

[0015] Further advantages can be achieved if, in a fuel cell tower according to the invention, at least two compression layers are arranged one above the other, at least partially overlapping, in particular completely or essentially completely overlapping. Such multiple compression layers can also be referred to as sandwich compression layers. They preferably have identical or essentially identical geometric extensions, so that in their overlapping regions they correspondingly increase the thickness of the entire combination of all compression layers. Due to the combination and the multi-layer arrangement of the compression layers, for example, the innermost compression layer can be in direct contact with the fuel cell stack. The outermost of such compression layers can then contact the side wall on the inside.Thus, multilayer designs with multiple compression layers provide even more flexibility in the advantages of the invention. In particular, the costs for the individual compression layers can be reduced in this way, and greater flexibility with regard to the flexible selection of different numbers of compression layers can be achieved. It is also conceivable that the different selection of compression layers could provide different thermal requirements, different thermal densities, different thermal sealing options, and / or different compression capabilities. This has the advantage of increasing mechanical stability.Further advantages can also be achieved if, in a fuel cell tower according to the invention, the at least two compression layers are identical or substantially identical in terms of the material, the geometric extension, and / or the structure. The identical design of the compression layers allows the overall thickness of all compression layers to be varied in any way without having to forego the modular design. This leads to a further cost reduction and a simplification of the assembly steps of such a fuel cell tower.

[0016] It may also be advantageous if, in a fuel cell tower according to the invention, a pressure distribution layer is arranged between the side wall and the at least two fuel cell stacks, in particular between two compression layers and / or between the compression layer and the side wall. Such a pressure distribution layer differs from the compression layers in particular in that it is designed as a rigid or stable pressure distribution layer. In comparison to the flexibly compressible compression layers, this pressure distribution layer is therefore able to ensure a flat distribution of the laterally applied pressure. This makes it possible to provide better uniformity, in particular between different compression layers. Such a pressure distribution layer is also preferably designed in a high-temperature version, since it is located in the hot interior as the housing space of the fuel cell tower.

[0017] It is further advantageous if, in a fuel cell tower according to the invention, the side wall has a flat extension which is larger than the side opening, so that the side wall overlaps with the opening edges surrounding the side opening. Such opening edges are therefore surrounding sections which can, for example, also be provided with corresponding mounting options, bolt receptacles or thread specifications. This additional lateral overlap allows further protection against unwanted leaks of the housing to the environment. It is also possible to ensure tightness with greater reliability using simple assembly steps, since this overlap can be easily provided by a fitter. It can also be advantageous if, in a fuel cell tower according to the invention, the side wall has a thickness step for at least partial insertion into the side opening.In other words, a circumferential rib or even a complete jump in the overall thickness of the side wall can be provided. This thickness step can then be used as a stop or centering aid if the side wall can be used to close the side opening. Such a thickness step is intended to serve as a positioning or centering aid, preferably circumferential or essentially circumferential. It facilitates positioning as an assembly step and thus provides improved guidance for the installer.

[0018] It can also be advantageous if, in a fuel cell tower according to the invention, the at least one compression layer has a thermal load limit above the operating temperature of the fuel cell stack. As already explained several times, such a fuel cell tower is, in particular, a high-temperature fuel cell system. Since operating temperatures of above 800 degrees Celsius can be expected in such a high-temperature fuel cell system, the materials for the compression layer, but also for the previously explained pressure distribution layer, are preferably also heat-resistant. One possible material for such a compression layer is known as Kaowool. This can be used because it has the desired sealing functionality, the desired compression functionality, and the desired thermal load limit.The same applies accordingly to the aforementioned pressure distribution layer. It is also advantageous if the at least one compression layer has electrical insulation and is made of a material that is, in particular chemically, compatible with the fuel cell tower.

[0019] Further advantages can also be achieved if, in a fuel cell tower according to the invention, the fuel cell stacks are designed for operation as a high-temperature fuel cell system. Such a high-temperature fuel cell system can also be referred to as an SOFC system. The temperatures are expected to be in the range of 800 to 1000 degrees Celsius, in particular. As already indicated, such a fuel cell can be designed as an open cathode, so that a lateral flow along a flow direction, in particular transverse to the stack direction, is provided for an operating gas, in particular air. In principle, such a fuel cell system can also be designed with a closed cathode.

[0020] The fuel cell tower according to the invention can also be designed, in particular, with electrolysis cells as a so-called SOEC system. In this case, the air side forms the anode and the fuel side the cathode. Consequently, in an open design, the air side is open. The SOEC system can also be designed as a CO-SOEC or as a reversible SOEC system (can be operated in both SOEC and SOFC mode).

[0021] It is also advantageous if, in a fuel cell tower according to the invention, the fuel cell stack has a flow direction for at least one operating gas, wherein the side wall is aligned parallel or substantially parallel to the flow direction. In other words, the side wall will now have no inlets or outlets for operating gas. Rather, the side wall is provided as a passive component during operation. The side wall only closes the side opening, which is an aid and an access point for assembly steps during the manufacture and assembly of the fuel cell tower. By designing the fuel cell stack in the form of an open cathode, the operating gas, in particular in the form of air, is supplied along the flow direction. The connections for the supply air and the exhaust air are accordingly formed separately from the side opening.The flow direction can in particular be aligned perpendicular to the stacking direction.

[0022] The present invention also relates to a housing for a fuel cell system according to the present invention. Such a housing is characterized in that it has at least one side opening, which is closed by the side wall and, on the inside thereof, in contact with at least one compression layer. Here, too, contact with the compression layer can be provided directly or indirectly. Such a housing therefore offers the same advantages as have been explained in detail with reference to a fuel cell tower according to the invention. The present invention also relates to a set of at least two fuel cell towers according to the invention, wherein the at least two fuel cell towers are at least electrically connected to one another. More than two fuel cell towers can also be provided.The fuel cell towers are electrically and advantageously also fluidically connected to each other and are arranged, for example, in at least one, two, or more rows. Alternatively, they can advantageously be arranged in a circular, star-shaped, annular, or rectangular configuration. If at least two fuel cell towers are provided, it may be advantageous to omit the aforementioned side wall.

[0023] The present invention also provides an assembly method for assembling a fuel cell tower according to the invention. Such an assembly method is characterized by the following steps:

[0024] - Arranging at least two fuel cells in the housing space of the housing,

[0025] - Arranging at least one compression layer in at least one side opening of the housing,

[0026] - closing the at least one side opening with a side wall, wherein the at least one compression layer contacts the at least two fuel cell stacks and an inner side of the side wall in a sealing manner.

[0027] Through the manufacture and assembly of a fuel cell tower according to the invention, an assembly method according to the invention also provides the same advantages as those explained in detail with reference to a fuel cell tower according to the invention. Here, too, the contacting configuration of the compression layer with a fuel cell stack and / or the interior can be provided directly or indirectly.

[0028] An assembly method according to the invention can be further developed such that, prior to the introduction of the at least one compression layer, a further assembly step is performed on the fuel cell stacks through the at least one side opening. Such an assembly step can, for example, provide an electrically conductive connection between the individual assembly stacks. Additional assembly steps for the desired sealing, weighting of the individual fuel cell stacks, and even the insertion of electrical insulation components are also conceivable in principle.

[0029] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. They show schematically:

[0030] Fig. 1 a first step of an assembly method according to the invention,

[0031] Fig. 2 the completion of an assembly method according to the invention,

[0032] Fig. 3 shows an embodiment of a partial section of a fuel cell tower according to the invention,

[0033] Fig. 4 shows a further development of the embodiment of Figure 3,

[0034] Fig. 5 shows a further development of the embodiment of Figures 3 and 4,

[0035] Fig. 6 shows a further development of the embodiment of Figures 3, 4 and 5.

[0036] An assembly method according to the invention, which produces a fuel cell tower 10 according to the present invention, is explained in more detail with reference to Figures 1 and 2. Here, a housing 20 can be clearly seen, which largely encloses a housing space 22. Four fuel cell stacks 30 are arranged inside this housing space 22, which are stacked one above the other along a stacking direction SR. On the right-hand side, the housing 20 is also provided with a side opening 24, so that access to this housing space 22 and thus to the fuel cell stacks 30 is possible. This access can be used, for example, for inserting the fuel cell stacks 30. In particular, however, the side opening 24 serves to ensure further assembly steps, for example insulating or electrically connecting the fuel cell stacks 30.

[0037] In Figure 1, the flow direction DR is also indicated perpendicular to the plane of the drawing. In other words, the fuel cell stacks 30 are designed as open cathode systems, so that operating gas can now be supplied and discharged as cathode gas perpendicular to the plane of the drawing along the flow direction DR. To ensure the desired sealing of a bypass on the fuel cell stacks 30, an assembly process for closing this side opening 24 is now carried out.

[0038] Figure 1 shows that two components are essentially required for this. First, there is the compression layer 50. This can be made of Kaowool, for example, and can thus combine the desired flexible compressibility with heat-temperature resistance and sealing functionality. This compression layer 50 is then inserted into the side opening 24, which is subsequently closed with the side wall 40. For closing, the side wall 40 is provided with a thickness shoulder 44, which helps the installer ensure centered positioning of the side wall 40 relative to and within the side opening 24. For closing, the inner side 42 of the side wall thus contacts the compression layer 50 and thus also presses it against the fuel cell stack 30 in a contacting manner.

[0039] The result of the preceding assembly steps is shown in Figure 2. Here, it is clearly visible that not only has the side opening 24 been completely closed, but also that the compression layer 50 is in a clamped position, contacting the inner side 42 of the side wall 40 and contacting the fuel cell stacks 30. This allows for a combination of mechanically secure positioning with a circumferential seal, as well as the possibility of variation in the event of thermal linear expansion of the fuel cell stacks 30.

[0040] Figure 3 schematically shows a partial section through an arrangement of a housing 20 according to the invention. Here, again, a part of a fuel cell stack 30 is shown schematically, which is now connected to the side wall 40 in a force-transmitting manner via the compressible compression layer 50.

[0041] Figure 4 shows a further development in which two compression layers 50 are sandwiched together in a completely overlapping manner. The function is identical, but by doubling the total thickness of all compression layers 50, a correspondingly higher compressive capacity has been combined with a correspondingly higher compensating function.

[0042] Figure 5 shows the use of a pressure distribution layer 60. This is capable of ensuring additional distribution of transverse pressures, in Figure 5 from left to right or from right to left, across the compression layer 50. This is particularly useful when, as shown in Figure 6, the pressure distribution layer 60 is surrounded on both sides by compression layers 50. In Figure 6, the outermost compression layer 50 is also thinner, as this can further reduce the overall geometry of the fuel cell stack.

[0043] The above explanation of the embodiments describes the present invention exclusively by way of examples.

[0044] List of reference symbols

[0045] 10 Fuel cell tower

[0046] 20 housings

[0047] 22 Housing space

[0048] 24 side opening

[0049] 25 opening edge

[0050] 30 fuel cell stacks

[0051] 40 side wall

[0052] 42 Inside

[0053] 44 thick heel

[0054] 50 compression layer

[0055] 60 pressure distribution layer

[0056] SR stacking direction

[0057] DR flow direction

Claims

Patent claims 1. A fuel cell tower (10) of a fuel cell system, comprising a housing (20) having a housing space (22) in which at least one fuel cell stack (30) is arranged, wherein the housing (20) has at least one side opening (24) which is closed by a side wall (40), characterized in that between the side wall (40), which closes the at least one side opening (24), and the at least one fuel cell stack (30), at least one compressible compression layer (50) is arranged, which at least partially contacts the fuel cell stack (30) and an inner side (42) of the side wall (40) in a sealing manner.

2. Fuel cell tower (10) according to claim 1, characterized in that in the housing space (22) at least two fuel cell stacks (30) are arranged one above the other along a stacking direction (SR).

3. Fuel cell tower (10) according to claim 1 or 2, characterized in that the at least one compression layer (50) extends over the entire or substantially the entire side opening (24).

4. Fuel cell tower (10) according to one of the preceding claims, characterized in that at least two compression layers (50) are arranged one above the other in an at least partially overlapping manner, in particular completely or substantially completely overlapping manner.

5. Fuel cell tower (10) according to claim 4, characterized in that the at least two compression layers (50) are identical or substantially identical in terms of material, geometric extension and / or structure.

6. Fuel cell tower (10) according to one of the preceding claims, characterized in that a pressure distribution layer (60) is arranged between the side wall (40) and the at least two fuel cell stacks (30), in particular between two compression layers (50) and / or between a compression layer (50) and the side wall (40).

7. Fuel cell tower (10) according to one of the preceding claims, characterized in that the side wall (40) has a planar extension which is larger than the side opening (24), so that the side wall (40) overlaps with the opening edges (25) surrounding the side opening (24).

8. Fuel cell tower (10) according to one of the preceding claims, characterized in that the side wall (40) has a thickness step (44) for at least partial penetration into the side opening (24).

9. Fuel cell tower (10) according to one of the preceding claims, characterized in that the at least one compression layer (50) has a thermal load limit above the operating temperature of the fuel cell stack (30).

10. Fuel cell tower (10) according to one of the preceding claims, characterized in that the fuel cell stacks (30) are designed for operation as a high-temperature fuel cell system. 1 1. Fuel cell tower (10) according to one of the preceding claims, characterized in that the fuel cell stacks (30) have a flow direction (DR) for at least one operating gas, wherein the side wall (40) is aligned parallel or substantially parallel to the flow direction (DR).

12. Housing (20) for a fuel cell tower (10) with the features of one of claims 1 to 11, characterized in that it has at least one side opening (24) which is closed by a side wall (40) and on the inside (42) thereof in contact with at least one compression layer (50).

13. Set of at least two fuel cell towers (10) according to one of claims 1 to 11, characterized in that the at least two fuel cell towers (10) are at least electrically connected to one another.

14. Assembly method for assembling a fuel cell tower (10) having the features of one of claims 1 to 11, comprising the following steps: - arranging at least two fuel cells (30) in the housing space (22) of the housing (20), - arranging at least one compression layer (50) in at least one side opening (24) of the housing (20), - closing the at least one side opening (24) with a side wall (40), wherein the at least one compression layer (50) contacts the at least two fuel cell stacks (30) and an inner side (42) of the side wall (40) in a sealing manner.

15. Assembly method according to claim 14, characterized in that before the introduction of the at least one compression layer (50), a further assembly step is carried out on the fuel cell stacks (30) through the at least one side opening (24).

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