Electrochemical stacks and mounting assemblies for such stacks
The electrochemical stack is suspended from a support frame to manage thermal expansion, ensuring stable operation and cost-effective media handling by eliminating the need for compensating elements, thus preventing damage and leakage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2024-04-16
- Publication Date
- 2026-05-11
AI Technical Summary
Existing electrochemical stacks face challenges in managing thermal expansion during operation, which can lead to damage of supply lines due to the movement of the lower plate relative to the ground, especially in large stacks with numerous cells, necessitating complex and costly compensating elements.
The electrochemical stack is designed with connections at the upper end, allowing it to be suspended from a support frame, with suspension sections on the upper plate preventing the lower plate from contacting the ground, thus maintaining a constant distance from the ground despite thermal expansion, eliminating the need for complex compensating elements.
This design ensures stable operation without additional compensating elements, reducing costs and preventing leakage or premature wear, particularly in large stacks, by evenly distributing the stack's weight and maintaining consistent access for media supply and discharge.
Smart Images
Figure 2026514491000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an electrochemical stack used, for example, to generate an electric current from chemical energy or to generate hydrogen and oxygen using an electric current, and an attachment assembly for attaching such a stack.
Background Art
[0002] Electrochemical stacks have various application areas. An electrochemical stack is used, for example, as a fuel cell to generate an electric current from chemical energy, or in the reverse application, as an electrolyzer to generate hydrogen and oxygen by electrochemical decomposition using an electric current. In that case, hydrogen can be converted back into an electric current at a later point or used as a starting material for other chemical processes. In that case, an electrochemical stack usually includes a relatively large number of electrochemical cells in which the actual reaction takes place. An electrochemical cell consists, briefly speaking, of an anode chamber and a cathode chamber separated from each other by a semipermeable membrane coated with an electrode. The anode chamber and the cathode chamber are filled or flowed through with a liquid, especially water, or a gas during operation.
[0003] In an electrolyzer, a DC voltage is applied between the electrodes, whereby the water entering the anode chamber is decomposed and hydrogen diffuses into the cathode chamber. The amount of hydrogen generated is determined by the area of the membrane. In order to obtain the largest possible yield, the individual electrochemical cells are formed very flat, whereby a large number of such cells can be stacked on top of each other, and accordingly the total area of the membrane becomes large. Water is supplied to all the cells via channels extending perpendicular to the electrochemical cells, and the generated gas is led out via further channels. In order to ensure the tightness of the cells, the cell stack is arranged between a lower plate and an upper plate, which are clamped with a large force. The clamping device required for that consists, for example, of a plurality of clamping screws arranged around the cell stack or a clamping band.
[0004] During operation, the electrochemical cell needs to be supplied with water and a gas, such as hydrogen or air, and the generated gas and any unused water must be discharged. If necessary, additional cooling water is also supplied and discharged. For this purpose, the electrochemical stack needs to have corresponding connections, which are preferably located on an easily accessible upper plate. In this case, the lower plate of the stack is mounted on a holding device.
[0005] Heat is generated during the operation of the stack, leading to thermal expansion. This changes the distance between the lower and upper plates, and in relatively large stacks with hundreds of electrochemical cells, this distance can increase by several millimeters. Therefore, the supply lines must have compensating elements to prevent damage to the supply lines on the upper plate due to the upper plate's movement relative to the ground. [Overview of the project]
[0006] In contrast, the electrochemical stack according to the present invention has the advantage that the electrochemical stack can be operated using connections necessary for operation at the upper end, i.e., the upper plate, and that there is no need to provide a compensation element in the supply line to compensate for the thermal expansion of the stack, or only a very simple, and therefore cost-effective, compensation element is required. In this case, the electrochemical stack includes a plurality of electrochemical cells, which are oriented horizontally and positioned between the upper and lower plates of the stack. The upper and lower plates are fastened together by a fastening device. The upper plate has at least one connection formed therein for supplying or discharging gaseous and / or liquid media to or from the electrochemical cells. The upper plate has suspension sections (Aufhaengungen) formed to attach the electrochemical stack to a support frame (Gestellrahmen), and the lower plate floats freely.
[0007] The electrochemical stack according to the present invention can be suspended on a corresponding support frame at the suspension section, thereby preventing the lower plate from contacting the ground. During operation, if the stack heats up and expands, the distance between the upper plate and the ground remains constant, but the lower plate moves somewhat toward the ground to the same extent as the stack's expansion. Since the upper plate is always at the same height above the ground, the supply and discharge lines can be fixed there without compensating elements, which results in significant savings, especially in the case of large, high-performance electrolytic cells or fuel cells where the cross-section and thickness of the lines are large and therefore inflexible.
[0008] In the first advantageous embodiment, the suspension sections are formed on the outer edge of the top plate. In this case, the suspension sections are preferably distributed across the width of the top plate to evenly distribute the stack weight on each individual suspension section and the support frame. Electrochemical stacks are typically heavy, sometimes exceeding 1 ton. In such cases, uneven loading of the stack at the suspension sections can lead to leakage between electrochemical cells, at least in the long term, and this must be avoided at all costs.
[0009] Furthermore, to avoid hindering the even distribution of water in the electrochemical cell, it is advantageous for the suspension system to be positioned in a plane parallel to the electrochemical cell. This supports the even distribution of water in the electrochemical cell and prevents premature wear.
[0010] Advantageously, the suspension is formed as bolts protruding laterally from the top plate. The bolts can withstand large forces and are easy to install. Alternatively, the suspension can be formed as metal rails, preferably fixed to opposing sides of the top plate. The metal rails rest flat on the frame and can be easily secured there, for example, by screw fastening.
[0011] The mounting assembly according to the present invention comprises an electrochemical stack and a support frame, wherein the electrochemical stack abuts against the support frame by a suspension, thereby allowing the lower plate to float freely. Thus, the stack can expand without issue due to the unavoidable heat generated during operation, without mechanical load being placed on the connections for the required liquids and gases. The support frame is advantageously prepared to connect to the suspension to create a mechanically stable connection with the electrochemical stack and to reliably hold the electrochemical stack in the desired position. [Brief explanation of the drawing]
[0012] [Figure 1] This is a perspective view showing a mounting device (Montageeinrichtung) with two stacks. [Figure 2] This is an enlarged, detailed view of the suspension region shown in Figure 1. [Figure 3] Figure 1 is a side view of the mounting assembly. [Figure 4] This figure shows another mounting device having a stack and a second embodiment of the suspension section. [Figure 5] Figure 4 is a detailed view of the mounting device. [Figure 6] This is a detailed view of another mounting device similar to Figure 5. [Modes for carrying out the invention]
[0013] An electrochemical stack according to the present invention and a mounting device for this stack are shown in the drawings.
[0014] Figure 1 shows two electrochemical stacks 1 according to the present invention in their mounting positions. Each electrochemical stack 1 contains multiple electrochemical cells 2 stacked vertically. Each individual electrochemical cell 2 is formed flat and is typically only a few millimeters thick, so that the stack 1 can contain hundreds of cells 2. The electrochemical cells 2 are located between a lower plate 3 and an upper plate 4 that form the lower or upper end of the stack 1. The lower plate 3 and the upper plate 4 are pressed together by a number of fastening screws 5 to seal the electrochemical cells 2 to each other and to the outside. In this case, the fastening screws 5 are distributed around the lower plate 3 or the upper plate 4 to achieve an even pressing force. Since a large pressing force is usually required that acts as evenly as possible distributed across the entire cross-section of the electrochemical cell 2, both the lower plate 3 and the upper plate 4 are robustly constructed from metal material. Two connectors 8 and 9 are provided on the upper plate 4 to supply the liquids and gases required during the operation of the electrochemical cells 2. Water or other liquid is supplied to all cells 2 through channels that extend vertically through the electrochemical stack 1. The resulting gas or liquid is led out through other channels and either regenerated or discharged outside the electrochemical stack 1.
[0015] Two electrochemical stacks 1 are suspended from a support frame 15. The support frame 15 comprises upper transverse struts 315a and lower transverse struts 315b, as well as front longitudinal struts 215a and rear longitudinal struts 215b, and four vertical struts 115 that are firmly connected, for example, by welding or screw fastening. The electrochemical stacks 1 are suspended from the support frame 15. To this end, the edge 14 of the top plate 4 is provided with two suspension points 17 in the form of bolts 19, one at the front and one at the rear opposite it, which rest on either the front longitudinal strut 215a or the rear longitudinal strut 215b. As shown again in an enlarged view in Figure 2, each bolt 19 is hooked onto a fork-shaped housing 20, which prevents the electrochemical stacks 1 from shifting position, but allows them to be lifted slightly above the support frame 15 if necessary. To this end, the housing section 20 is firmly connected to the front longitudinal strut 215a or the rear longitudinal strut 215b, for example, by welding.
[0016] Figure 3 shows a narrow-side plan view of the support frame 15 having an electrochemical stack 1. Connections 8 and 9 on the top plate 4 are connected to lines 11 and 12, through which the required water or gas is supplied and discharged. During operation of the electrochemical stack 1, which may be an electrolytic cell for producing hydrogen and oxygen from water, the stack 1 becomes very hot. This causes the electrochemical cells 2, and thus the entire stack 1, to expand, and because there are many cells 2, the bottom plate 3 may be moved down by several millimeters, as indicated by the arrows in Figure 3. However, since the stack 1 is held in place only by bolts 19 connected to the top plate 4, the top plate 4 does not move perpendicular to the support frame 15. This allows lines 11 and 12 to be connected to the electrochemical stack 1 in a fixed position without the need for compensating elements to compensate for the changed height.
[0017] In FIG. 4, another exemplary embodiment of the attachment of the electrochemical stack 1 according to the present invention and its attachment to the pedestal frame 15 is shown. Instead of the bolts 19, rails 22 forming suspension portions 17 are provided here on the front and back surfaces of the upper plate 4, respectively. As shown in an enlarged view in FIG. 5, the rails 22 are connected to the longitudinal struts 215a, 215b by a plurality of screws 23 in order to attach the stack 1 to the pedestal frame 15. By the rails 22, the weight of the stack 1 can be more evenly distributed to the pedestal frame 15, improving stability.
[0018] FIG. 6 shows another exemplary embodiment of the attachment of the stack 1 in the pedestal frame 15. Instead of the rails 22 shown in FIG. 5, forklift rails (Staplerschiene) 25 are provided on the front and back sides of the stack 1, respectively. This consists of hollow profiles dimensioned such that the fork tips of a forklift can be inserted respectively for transporting the stack 1, lifting it into the pedestal frame 15, or removing it therefrom. Here, screws 23 are also provided for fixing, and the screw heads are arranged inside the forklift rails 25.
Explanation of reference numerals
[0019] 1 Electrochemical stack 2 Electrochemical cell 3 Lower plate 4 Upper plate 5 Tightening screw 8, 9 Connection part 11, 12 Line 14 Outer edge part 15 Pedestal frame 17 Suspension part 19 Bolt 20 Accommodation part 22 Rail 23 Screw 25 Forklift rail 215a Front longitudinal strut 215b Rear longitudinal strut 315a Upper horizontal strut 315b Lower lateral strut 115 Vertical strut
Claims
1. An electrochemical stack (1) comprising a plurality of electrochemical cells (2) arranged horizontally between an upper plate (4) and a lower plate (3) of the electrochemical stack (1), wherein the upper plate (4) and the lower plate (3) are fastened together by a fastening device (5) and are parallel to each other, and the electrochemical stack (1) comprises at least one connection portion for supplying or discharging a gaseous or liquid medium to or from the electrochemical cells (2), wherein the connection portion is formed on the upper plate (4), in the electrochemical stack (1), The electrochemical stack is characterized in that the upper plate (4) has a suspension portion (17) for attaching the electrochemical stack (1) to a support frame (15), and the lower plate (3) is able to float freely.
2. The electrochemical stack according to claim 1, characterized in that the suspension portion (17) is formed on the outer edge portion (14) of the upper plate (4).
3. The electrochemical stack according to claim 2, characterized in that a plurality of suspension portions (17) are dispersed around the outer edge portion (14) of the upper plate (4).
4. The electrochemical stack according to claim 3, characterized in that the multiple suspension portions (17) are located on the same plane.
5. The electrochemical stack according to claim 4, characterized in that the plane is oriented parallel to the electrochemical cell (2).
6. The electrochemical stack according to any one of claims 1 to 5, characterized in that the suspension portion (17) is formed as a bolt (19) protruding laterally from the upper plate (4).
7. The electrochemical stack according to any one of claims 1 to 5, characterized in that the suspension portion (17) is formed as a metal rail (22).
8. The electrochemical stack according to claim 7, characterized in that metal rails (22) are arranged on opposite sides of the upper plate (4).
9. A mounting assembly for mounting an electrochemical stack according to any one of claims 1 to 8, comprising a support frame (15), wherein the electrochemical stack (1) is in contact with the support frame by the suspension portion (17), thereby allowing the lower plate (3) to float freely, and the electrochemical cell (2) is oriented horizontally.
10. The mounting assembly according to claim 9, characterized in that the suspension portion (17) is screw-fastened to the mounting frame (15).
11. The mounting assembly according to claim 9, characterized in that the suspension portion (17) has the form of a bolt (19), and the mounting frame (15) has a housing portion (20) for the bolt (19).