Electrochemical stack and mounting assembly for a stack of this type
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-04-16
- Publication Date
- 2026-03-04
AI Technical Summary
Existing electrochemical stacks face challenges in managing thermal expansion during operation, which can lead to mechanical stress on connections for liquids and gases, requiring compensating elements in supply lines to prevent damage, especially in large systems like electrolyzers or fuel cells.
The electrochemical stack design features a cover plate with suspensions that allow the base plate to float, maintaining a constant distance from the floor despite thermal expansion, eliminating the need for compensating elements in supply lines by suspending the stack on a frame, using bolts or metal rails for secure attachment.
This design reduces mechanical stress on connections, prevents leaks, and saves costs by eliminating the need for compensating elements in supply lines, ensuring stable and efficient operation even in large and powerful systems.
Smart Images
Figure EP2024060277_31102024_PF_FP_ABST
Abstract
Description
[0001] title
[0002] Electrochemical stack and assembly arrangement for such a stack
[0003] The invention relates to an electrochemical stack, such as is used, for example, for generating electrical current from chemical energy or for producing hydrogen and oxygen with the aid of electrical current, and to a mounting arrangement for mounting such a stack.
[0004] State of the art
[0005] Electrochemical stacks have a variety of applications. For example, they are used as fuel cells to generate electricity from chemical energy, or in the reverse application as electrolyzers to produce hydrogen and oxygen through electrochemical splitting using electrical current. The hydrogen can then be converted back into electrical current at a later time or it can serve as a starting material for other chemical processes. Electrochemical stacks typically feature a large number of electrochemical cells in which the actual reaction takes place. Simply put, the electrochemical cells consist of an anode compartment and a cathode compartment separated by a semipermeable membrane coated with electrodes. During operation, the cathode and anode compartments are filled with, or flowed through by, liquids—especially water—or gas.
[0006] In an electrolyzer, a direct voltage is applied between the electrodes, which splits the water in the anode compartment and causes the hydrogen to diffuse into the cathode compartment. The surface area of the membrane is crucial for the amount of hydrogen produced. To achieve the highest possible yield, the individual electrochemical cells are designed to be very flat, allowing a large number of such cells to be stacked on top of one another, resulting in a correspondingly large total membrane area. All of the cells are supplied with water via channels running perpendicular to the electrochemical cells, and the resulting gases are discharged via additional channels. To ensure the cells are leak-tight, the cell stack is arranged between a base plate and a cover plate, which are clamped together with great force.The clamping device required for this consists, for example, of several clamping screws arranged around the circumference of the cell stack or of clamping straps.
[0007] During operation, water and gases—such as hydrogen or air—must be supplied to the electrochemical cells, and the resulting gases and unused water must be removed. Additional cooling water is also supplied and removed as needed. For this purpose, the electrochemical stack must have appropriate connections, preferably located on the cover plate where they are easily accessible. The stack is placed with the base plate on a support.
[0008] During operation, the stack generates heat and thus thermal expansion. This changes the distance between the base plate and the cover plate, which can increase by several millimeters in larger stacks with several hundred electrochemical cells. The supply lines on the cover plate must therefore be fitted with compensating elements to prevent damage caused by the rise and fall of the cover plate relative to the floor.
[0009] Advantages of the invention
[0010] The electrochemical stack according to the invention has the advantage that the electrochemical stack can be operated at its upper end, i.e. the cover plate, with the connections required for operation, wherein the supply lines either do not require any compensating elements to compensate for the thermal expansion of the stack, or only very simple and therefore cost-effective ones. The electrochemical stack comprises a plurality of electrochemical cells that are aligned horizontally and arranged between a cover plate and a base plate of the stack, wherein the cover plate and the base plate are clamped against one another by a clamping device. At least one connection for supplying or discharging gaseous and / or liquid media to or from the electrochemical cells is formed on the cover plate.The cover plate has suspensions designed to attach the electrochemical stack to a rack frame, with the base plate floating freely.
[0011] The electrochemical stack according to the invention can be suspended from a suitable frame by its suspensions, so that the base plate does not touch the floor. If the stack expands due to heating during operation, the distance between the cover plate and the floor remains constant, while the base plate moves slightly toward the floor as the stack expands. Since the cover plate always remains the same height above the floor, the supply and discharge lines can be attached there without compensating elements. This leads to significant savings, especially in large and powerful electrolyzers or fuel cells, since the lines here have large cross-sections and wall thicknesses and are therefore inflexible.
[0012] In a first advantageous embodiment, the suspensions are formed on the outer edge of the cover plate. These are preferably distributed across the width of the cover plate to achieve an even distribution of the stack weight among the individual suspensions and across the rack frame. Electrochemical stacks are typically heavy, weighing more than a ton. Uneven loading of the stack in the suspension must be avoided at all costs, as this can lead to leaks between the electrochemical cells, at least in the long term.
[0013] To avoid compromising the even distribution of water in the electrochemical cells, it is also advantageous if the suspensions are arranged in a plane parallel to the electrochemical cells. This supports the even distribution of water in the electrochemical cells, preventing premature wear.
[0014] Advantageously, the suspensions are designed as bolts that protrude laterally from the cover plate. Bolts can absorb large forces and are easy to install. Alternatively, the suspensions can also be designed as metal rails, preferably attached to opposite sides of the cover plate. These rest flat on the frame and can be easily secured there, for example, with a screw connection.
[0015] The mounting arrangement according to the invention comprises an electrochemical stack and a frame, to which the electrochemical stack rests with its suspensions, allowing the base plate to float freely. This allows the stack to expand easily during operation due to the inevitable heating without mechanical stress on the connections for the required liquids and gases. The frame is advantageously prepared for connection to the suspensions to create a mechanically stable connection to the electrochemical stack and securely hold it in the desired position.
[0016] drawing
[0017] The drawing shows an electrochemical stack according to the invention and an assembly device for this stack.
[0018] Fig. 1 shows an assembly device with two stacks in perspective view,
[0019] Fig. 2 is a detailed enlargement of Fig. 1 in the area of the suspension,
[0020] Fig. 3 is a side view of the mounting arrangement according to Fig. 1,
[0021] Fig. 4 shows another assembly device with a stack and a second embodiment of the suspension,
[0022] Fig. 5 a detailed view of the assembly device of Fig. 4 and
[0023] Fig. 6 is a detailed view of another assembly device similar to Fig. 5.
[0024] Description of the embodiments
[0025] In Fig. 1, two electrochemical stacks 1 according to the invention are shown in a
[0026] Mounting position shown. Each electrochemical stack 1 comprises a plurality of electrochemical cells 2 that are stacked one above the other. The individual electrochemical cells 2 are flat and generally only a few millimeters thick, so that a stack 1 can comprise several hundred cells 2. The electrochemical cells 2 are arranged between a base plate 3 and a cover plate 4, which form the lower and upper ends of the stack 1, respectively. The base plate 3 and the cover plate 4 are pressed against one another by a plurality of clamping screws 5 in order to seal the electrochemical cells 2 from one another and from the outside. The clamping screws 5 are arranged distributed over the circumference of the base plate 3 and cover plate 4 in order to achieve a uniform contact force.Both the base plate 3 and the cover plate 4 are sturdily constructed from a metallic material, as high contact forces are generally required, which should be distributed as evenly as possible across the entire cross-section of the electrochemical cells 2. To supply the liquids and gases required for the operation of the electrochemical cells 2, two connections 8, 9 are attached to the cover plate 4. The water or other liquid is supplied to all cells 2 via channels that run vertically through the electrochemical stack 1. The resulting gases or liquids are discharged via further channels and processed or removed outside the electrochemical stack 1.
[0027] The two electrochemical stacks 1 are suspended in a frame 15. The frame 15 comprises four vertical struts 115, which are firmly connected to an upper cross strut 315a and a lower cross strut 315b, and further to a front longitudinal strut 215a and a rear longitudinal strut 215b, for example, by welded or screwed connections. The electrochemical stacks 1 are suspended in the frame 15. For this purpose, two suspensions 14 in the form of bolts 19 are attached to the edge 14 of the cover plate 4 on the front and the opposite, rear side. These suspensions rest on the front longitudinal strut 215a and the rear longitudinal strut 215b, respectively. As shown again in Fig. 2 on an enlarged scale, the bolts 19 are each suspended in a fork-shaped receptacle 20 so that the electrochemical stack 1 does not slip, but can be easily lifted upwards out of the frame 15 if necessary.For this purpose, the receptacles 20 are firmly connected to the front longitudinal strut 215a and the rear longitudinal strut 215b, for example by a welded connection. Fig. 3 shows a plan view of the narrow side of the frame 15 with the electrochemical stack 1. The connections 8, 9 on the cover plate 4 are connected to lines 11, 12 through which the required water or gases are supplied and removed. During operation of the electrochemical stack 1, which can be an electrolyzer for generating hydrogen and oxygen from water, for example, the stack 1 heats up considerably. This causes the electrochemical cells 2 and thus also the entire stack 1 to expand, which, due to the large number of cells 2, can move the base plate 3 downwards by several millimeters, as indicated by the arrow in Fig. 3.However, since the stack 1 is held exclusively by the bolts 19 connected to the cover plate 4, the cover plate 4 does not move vertically relative to the frame 15. This allows the lines 11, 12 to be rigidly connected to the electrochemical stack 1 without the need for compensating elements to accommodate changes in height.
[0028] Fig. 4 shows a further embodiment of the electrochemical stack 1 according to the invention and its assembly in the rack frame 15. Instead of the bolts 19, a rail 22 is attached to the front and rear of the cover plate 4, forming the suspension 14. The rails 22 are connected to the longitudinal struts 215a, 215b by several screws 23 to fix the stack 1 in the rack frame 15, as shown in an enlarged view in Fig. 5. The rails 22 distribute the weight of the stack 1 more evenly across the rack frame 15, which can improve stability.
[0029] Fig. 6 shows another embodiment for mounting the stack 1 on the rack frame 15. Instead of the rails 22—as shown in Fig. 5—a forklift rail 25 is attached to the front and rear of the stack 1. This rail consists of a hollow profile dimensioned so that a fork of a forklift can be inserted in each case to transport the stack 1, to lift it into the rack frame 15, or to remove it from it. Screws 23 are also provided here for fastening, the screw heads of which are arranged inside the forklift rail 25.
Claims
Claims 1 . Electrochemical stack (1) comprising a plurality of electrochemical cells (2) which are aligned horizontally and which are arranged between a cover plate (4) and a base plate (3) of the stack (1), wherein the cover plate (4) and the base plate (3) are clamped against one another by a clamping device (5) and are parallel to one another, and having at least one connection for supplying or discharging gaseous or liquid media to the electrochemical cells (2), wherein the connection is formed in the cover plate (4), characterized in that the cover plate (4) has suspensions (17) which are designed to fasten the electrochemical stack (1) to a frame (15), wherein the base plate (3) is freely suspended.
2. Electrochemical stack according to claim 1, characterized in that the suspensions (17) are formed on the outer edge (14) of the cover plate (4).
3. Electrochemical stack according to claim 2, characterized in that on the outer edge (14) of the cover plate (4) several suspensions (17) are arranged distributed over the circumference of the cover plate (4).
4. Electrochemical stack according to claim 3, characterized in that the suspensions (17) lie in one plane.
5. Electrochemical stack according to claim 4, characterized in that the plane is aligned parallel to the electrochemical cells (2).
6. Electrochemical stack according to one of claims 1 to 5, characterized in that the suspensions (17) are designed as bolts (19) which protrude laterally from the cover plate (4).
7. Electrochemical stack according to one of claims 1 to 5, characterized in that the suspensions (17) are designed as metal rails (22).
8. Electrochemical stack according to claim 7, characterized in that a metal rail (22) is arranged on opposite sides of the cover plate (4).
9. Mounting arrangement for mounting an electrochemical stack according to one of claims 1 to 8, comprising a frame (15) against which the electrochemical stack (1) rests with its suspensions (17), so that the base plate (3) floats freely and the electrochemical cells (2) are aligned horizontally.
10. Mounting arrangement according to claim 9, characterized in that the suspensions (17) are screwed to the frame (15).
11. Mounting arrangement according to claim 9, characterized in that the suspensions (17) have the shape of bolts (19) and receptacles (20) for these bolts (19) are formed on the frame (15).