Frame Structure of Electrolysis Device

Abstract

The present invention relates to a frame structure of an electrolysis apparatus that is capable of withstanding a corrosive environment and a radial pressure and receives an internal pressure. The present invention also relates not only to the use of the frame structure in high-pressure water electrolysis applications, but also to an electrolytic cell and an electrolysis apparatus provided with the frame structure.

Description

Technical Field

[0001] The present invention relates to the field of the frame structure of an electrolyzer.

Background Art

[0002] Depending on the industrial application, an electrolyzer may be operated at various pressures, and thus, it is required to withstand the mechanical stresses generated not only in the overall structure but also in individual components. The pressure conditions are defined by the chemistry, components, dimensions, and the industry in which it is used. Examples of high-pressure electrolyzers can be found, for example, in the field of proton exchange membrane (PEM) electrolyzers and alkaline water electrolysis (AWE) with an operating pressure exceeding 5 bar.

[0003] So far, for example, the self-frames of high-pressure electrolyzers for AWE applications have all been made of carbon steel or stainless steel, which provide an excellent mechanical system. However, due to the corrosion rate of these metals when immersed in a strong alkaline solution, it has an adverse effect not only on the service life of the electrolyzer but also on the overall performance of the electrolyzer. The corrosion of carbon steel or stainless steel affects the purity of the electrolyte, hinders the flow of the electrolyte, and causes the formation of sludge that may cause pressure loss and safety problems.

[0004] In contrast, in modern high-pressure AWE electrolyzers, the self-frame is made of high-quality engineering plastics such as, for example, PSU (polysulfone), PPS (polyphenylene sulfide), or PEEK (polyether ether ketone), and optionally reinforced with glass fibers. These materials are scientifically almost inert to the electrolyte, but their mechanical properties do not match those of steel. For example, their Young's modulus is 1 / 15 to 1 / 100 of that of steel at room temperature.

[0005] Engineering plastics can be used in the manufacture of the self-frame of a small pressurized electrolyzer where mechanical stress and deformation are limited. However, in large and / or high-pressure electrolyzers, self-frames made of these materials require a significant thickness to withstand mechanical stress and maintain mechanical deformation within acceptable limits. This approach is disadvantageous as it significantly increases the cost, dimensions, and weight of the electrolyzer.

[0006] The object of the present invention is to provide a frame structure for an electrolyzer that can withstand internal pressure regardless of its dimensions and the industry in which it is used, while limiting the cost of the self-frame, the dimensions of its components, and its weight, and combining the scientific resistance of engineering plastics to corrosive environments with the strong mechanical properties of steel.

[0007] A further object of the present invention is to provide an electrochemical cell and an electrolyzer comprising the frame structure according to the present invention, particularly for use in high-pressure water electrolysis applications.

Summary of the Invention

[0008] In a first aspect, the present invention relates to a frame structure suitable for use in an electrolyzer and optionally stackable.

[0009] The frame structure of the present invention comprises (i) at least a first and a second restraining structure, and (ii) at least a first and a second supporting structure. and comprises.

[0010] Each supporting structure typically has two main opposing faces and an outer edge of a total thickness T s of the outer edge.

[0011] The term "outer edge" refers to the region connecting the two opposing faces of the supporting structure, which may be flat, rounded, concave or convex, and / or may have ridges, corners, slopes or depressions.

[0012] The first and second support structures are arranged opposite to each other even if other elements are interposed therebetween, whereby their main opposing surfaces are essentially parallel to each other.

[0013] Typically, the main opposing surfaces of the support structures are substantially flat or exhibit a slightly concave or convex contour. However, the specific shape should be selected by those skilled in the art according to the practice. Similarly, the overall geometry of the support structures may vary in both size and shape. Typically, they exhibit a circular / elliptical section or a polygonal shape, but in principle any shape may be used. The support structures may comprise a housing suitable for accommodating any element that may be placed within an electrolytic cell, for example, electrodes, separators, elastic elements, bipolar plates, and / or current collectors, either alone or in combination.

[0014] The housing can be arranged on at least one of the two main opposing surfaces of each support structure. The housing may be a free space having an appropriate outer diameter around its edge for properly holding the electrodes and / or other elements. The housing may be a through-hole for exposing the electrode surface and promoting the electrochemical reaction on both sides.

[0015] Preferably, the support structure is made of an electrochemically inert material such as plastic, for example, to avoid the formation of sludge. The choice of material may depend on the application. In a corrosive environment such as alkaline water electrolysis, the support structure of the present invention can advantageously be made of high-quality engineering plastics, preferably polysulfone, polyphenylene sulfide, or polyether ether ketone, optionally reinforced with glass fibers.

[0016] In less demanding electrochemical applications, support structures made of polypropylene or other less expensive plastics can be fully used.

[0017] The first and second suppression structures are each located around the outer edge of the first and second support structures and completely or partially cover the exposed surface of the edge.

[0018] During operation of the piezochemical decomposition device, the support structure is subjected to a hydrostatic pressure equal to the stack operating pressure that radially deforms the suppression structure. Due to their relative positions, when the internal support structure comes into direct or indirect contact with the corresponding suppression structure, most of the mechanical stress is transmitted to the latter. Therefore, the suppression structure may be selected from a material that is mechanically more robust than the support structure and has less or negligible deformation.

[0019] In fact, unlike the support structure (which, as described above, is in contact with the electrolyte and is preferably selected from a compatible corrosion-resistant material), the suppression structure is not in contact with the electrolyte and preferably functions as a mechanical reinforcement of the support structure under pressure. To further reduce the possibility of deformation of the internal support structure and to keep the suppression structure away from the electrolyte, the suppression structure may advantageously be formed so as to minimize, preferably avoid, the overlap with either of the two main opposing surfaces of each support structure.

[0020] According to the present invention, each suppression structure is not a continuous unit but is composed of at least two separate segments, and each segment comprises at least two engagable elements.

[0021] The engagable elements are means for connecting, fixing and / or pressing two suppression structures against each other so that they can be fixed in a predetermined position. For example, the engagable elements may be through-holes that can be contacted via tie rods, screws, bolts or rivets. Although less preferred, the engagable elements may be formed in a male / female shape or other connection shape (or mechanical or other mechanism) suitable for making a highly reliable connection with each other.

[0022] The segments of each suppression structure preferably are arranged substantially adjacent to and continuously along the edge of the support structure.

[0023] Each restraining structure may be composed of any number of 2 or more segments, but for practical reasons, it is preferably a number between 2 and 8 segments for each restraining structure.

[0024] Since each restraining structure is composed of a plurality of individual segments that are not necessarily connected to each other, in order to ensure the mechanical stability of the frame structure, at least two engagable elements in the same segment of the first restraining structure face two engagable elements in two separate segments of the second restraining structure, and the segments of the first and second restraining structures are oriented with respect to each other.

[0025] Thereby, when the engagable means of the first restraining structure is coupled to the opposing engagable means of the second restraining structure, it is guaranteed that the two restraining structures obtain a configuration with rigidity and mechanical stability.

[0026] The segmented design of the external restraining structure can significantly reduce the amount of manufacturing scrap, facilitate the transportation of these structures, and simplify management / installation.

[0027] According to one embodiment, the restraining structure overlaps the outer edge of the support structure for at least 50%, preferably at least 70% of the width of the outer edge thickness T s (i.e., the width along the Z-axis in the figure). The higher the pressure in the electrolyzer and / or the larger the size of the electrolyzer, the higher the proportion of the edge covered by the restraining structure should be.

[0028] When the restraining structure adheres partially or completely to the support structure, it has the effect of counteracting the radially generated pressure in the cell during the electrolysis reaction. In fact, during the operation of a sealed electrochemical cell, the gas generation reaction increases the pressure inside the cell enclosure, i.e., inside the cell. Typically, terminal flanges are used to counteract the pressure acting perpendicular to the electrode surface. The frame structure of the present invention effectively addresses the radially outward pressure in the electrode plane.

[0029] According to another embodiment, the suppression structure has a width of less than 100% of the edge thickness T s and overlaps the outer edge of the support structure, i.e., it avoids the possibility that the edge is completely covered or there is direct contact between adjacent suppression structures. Since the suppression structure may be made of a material not suitable for this effect, this can prevent the suppression structures from releasing clamping force to each other. A suitable spacer may be inserted between the suppression structures. Furthermore, by leaving some space between adjacent suppression structures, room is ensured for inserting a useful device for monitoring cell voltage parameters.

[0030] According to another embodiment, when the number of support structures exceeds two, at least one suppression structure may be simultaneously arranged around the outer edges of at least two adjacent support structures. Thereby, the number of components required for assembling the electrolyzer can be reduced, and the installation of the electrolyzer becomes easier.

[0031] In the frame structure according to the present invention, at least two support structures may be arranged adjacent to each other and may optionally be separated by a gasket. The gasket may be accommodated in a suitable groove on the main surface of the support structure. In other embodiments, the gasket may be arranged outside the surface area of the support structure and sandwiched between two adjacent support structures.

[0032] In the frame structure according to the present invention, the first and second suppression structures are separated from each other by a spacer (optionally made of rubber). Thereby, the correct mutual position of the elements can be maintained. Also, it is ensured that the pressure from the clamping system of the electrolyzer is mainly transmitted to the support structure and its gasket system.

[0033] According to another embodiment, the outer edge of each support structure has a convex portion protruding along at least one of its outer peripheral edges, facilitating accommodation of the respective suppression structure within the resulting corners.

[0034] The suppression structure according to the present invention is preferably made of a material with high mechanical resistance for an internal support structure, such as metal. More preferably, they are made of steel, especially carbon steel or stainless steel. Alternatively, they may be made of composite materials. For example, they can be made of carbon fibers or composed of a metal core covered with a plastic outer surface to prevent corrosion.

[0035] All of the above materials give the external suppression structure sufficient robustness to effectively cancel out the radial forces received by the pressurized electrolysis device.

[0036] Those skilled in the art can easily recognize that due to the mechanical properties of the external suppression structure, the frame structure according to the above embodiment can have its overall dimensions significantly reduced compared to a self-frame made entirely of engineering plastics in the prior art. This also reduces the overall usage amount of expensive engineering plastics, having a positive impact on costs.

[0037] In yet another embodiment, in the frame structure according to the present invention, the support structure is substantially circular with a maximum outer diameter D F and the suppression structure is annular, divided into a plurality of arcuate segments. Each annular suppression structure has an inner diameter D i and an outer diameter D e and D i < D F < D e or D F < D i < D e < D. Depending on whether there are convex portions protruding from the support structure, the former or the latter condition applies respectively.

[0038] In a second aspect, the present invention relates to an electrochemical cell including the aforementioned frame structure, wherein at least a first support structure houses an anode, at least a second support structure houses a cathode, the anode and the cathode are arranged facing each other, and are optionally separated by a separator element such as a diaphragm or a membrane.

[0039] In a third aspect, the present invention relates to an electrolysis device comprising a plurality of electrochemical cells, each cell comprising the aforementioned frame structure, and the restraining structures being interconnected via tie rods that engage with at least two engagable elements (preferably through-holes) of each segment.

[0040] In a further embodiment of the electrolysis device according to the present invention, each frame structure preferably includes two internal support structures arranged between the first and second restraining structures, and the additional two support structures are arranged outside the peripheral restraining structure and are closed by two opposite end flanges.

[0041] The latter preferably does not come into direct contact with the restraining structure in order to avoid the pressure along the axial direction of the electrolysis device (i.e., the direction perpendicular to the electrodes) being directly released to the more rigid elements of the stack.

[0042] In a fourth aspect, the present invention relates to the use of the above electrolysis device for high-pressure (>5 bar) water electrolysis, preferably alkaline water electrolysis.

[0043] Some embodiments of the present invention will be described below by way of example with reference to the accompanying drawings, the purpose of which is only to show the mutual arrangement of the various elements related to the above embodiments of the present invention. The drawings are not to scale. The same numbers are used to indicate features having the same purpose / effect. The coordinate axes x, y, z are used in the same way throughout all the figures. The xy plane is substantially parallel to the two main faces of the internal support structure, while z is perpendicular to such a plane and defines the main longitudinal axis of the electrolysis device according to the present invention.

Brief Description of the Drawings

[0044]

Figure 1

[0045] The frame structure is composed of a first suppression structure (110), a second suppression structure (120), a first support structure (210), and a second support structure (220). These shapes are designed such that when the suppression structure is wrapped around the outer edge of the support structure and covers all or part of the width of the support structure along the Z direction, the adhesion between the suppression structure and the support structure becomes substantially uniform. The first suppression structure is composed of four identical and separate segments (111, 112, 113, 114). Generally, the suppression structure may not have the same segmentation, and the segments of individual suppression structures may also be different from each other. In this particular case, as can be seen from the figure, the second suppression structure is also composed of four identical and separate segments (125, 126, 127, 128), similar to the first suppression structure. Four holes are provided in all segments as engagable elements. The support structures (210, 220) are provided with housings (215, 225) for electrodes and other optional elements necessary for the operation of the cell. It should be noted that with the same-shaped suppression structure and the same segmentation, the assembly of parts and the management of spare parts may be simplified.

Figure 2

[0046] Figure 2(a) shows only one support structure (210) for clarity. Looking at the segment (111) of the first suppression structure (110), four engagable elements (010, 011, 012, 013) are observed, and all of them are arranged on the same segment (111). The second suppression structure (120) is oriented with respect to the first suppression structure (110), and the above-mentioned engagable elements (010, 011, 012, 013) can engage with the corresponding engagable elements (020, 021, 022, 023) belonging to two separate segments (125, 126) of the second suppression structure (120). The engagable elements are through-holes in this example and can engage through appropriate engagable means such as tie rods (901, 902).

[0047] Figure 2(b) shows how the first and second suppression structures (110, 120) are arranged with respect to the same coordinate set in the xy plane. The second suppression structure (120) is identical to the first suppression structure but is rotated by an angle (45° in this particular example), so the discontinuity points (01, 02, 03, 04, 05, 06, 07, 08) within the first and second suppression structures, i.e., where the suppression structures are divided, are offset from each other. As a result, at least two engagable elements (011, 012) of one and the same segment (111) of the first suppression structure (110) can face two engagable elements (021, 022) present in two separate segments (125, 126) of the second suppression structure. When engagable means such as tie rods connect the respective engagable elements of the two suppression structures, the resulting device is mechanically stabilized. A similar effect is obtained even when the suppression structure is in the shape of a continuous ring, but the amount of scrap and the package dimensions result in significantly higher manufacturing and transportation costs. In this figure, since the segments within each suppression structure are arranged substantially adjacent and continuously, the effect on the radial pressure, i.e., the pressure in the xy plane applied during the operation of the cell, is optimized.

Figure 3

[0048] Two suppression structures (110, 120) are shown. The first suppression structure (110) is suitable for wrapping around both support structures (200) and (210). The support structure (200) is suitable for accommodating a bipolar element (400) to which a current collector and an anode are welded on its surface. The support structure (210) is suitable for accommodating a cathode (600) and an elastic element (300). The separator (500) is sandwiched between the anode surface welded to the bipolar element (400) and the cathode (600). Similarly, the second suppression structure (120) is suitable for wrapping around both support structures (220) and (230). The support structure (220) is suitable for accommodating a bipolar element (450) to which a current collector and an anode are welded on its surface. The support structure (230) is suitable for accommodating a cathode (650) and an elastic element (350). The separator (550) is sandwiched between the anode surface welded to the bipolar element (450) and the cathode (650).

[0049] During assembly, the segments (125, 126, 127, 128) of the second suppression structure (120) are rotated 45° in the xy plane with respect to the corresponding segments (111, 112, 113, 114) of the first suppression structure (110).

Figure 4

[0050] Panel a) shows a section in the xy plane. Panel b) shows a partial section in the yz plane of the same electrolysis device. This partial section is a slice along the AA segment shown in panel a. Panel b) shows how a plurality of suppression structures (110, 120, 130, 140) are arranged with respect to a plurality of support structures (200, 210, 220, 230, 240, 250, 260, 270).

[0051] In this embodiment, each suppression structure covers two support structures at a time (e.g., (120) covers (220, 220)). The support structures have protrusions (221, 222, 223) that create a recessed space for accommodating the suppression structure. In this embodiment, the individual thickness T of the suppression structure c is approximately equal to 1.6T S and each covers approximately 80% of the individual thickness T of the support structure s .

[0052] The suppression structures are separated from each other by spacers (701, 702, 703). The suppression structures handle pressure applied in the xy plane, while the terminal flanges (800, 850) resist pressure in the z direction. It is desirable that the frame structure of the electrolysis device be assembled such that the suppression structure, which may advantageously be made of steel, does not come into direct contact with the metallic terminal flanges.

Figure 5

[0053] The second suppression structure (120) is identical to the first suppression structure but is rotated by an angle (180° in this particular example) within the xy plane, and the discontinuity points (01, 02, 03, 04, 05, 06) of the first and second suppression structures are offset from each other. As a result, at least two engagable elements (010, 011) of the same segment (111) of the first suppression structure (110) can face two engagable elements (020, 028) present in two separate segments (127, 125) of the second suppression structure. The same concept applies to each segment of each suppression structure.

[0054] In the description and claims of this application, the terms "comprise", "comprising", and "comprises" and variations thereof do not exclude the presence of other additional elements, components, or stages.

[0055] The descriptions of the documents, certificates, materials, devices, articles, etc. in this text are provided only for the purpose of explaining the background of the present invention, and it should not be understood that this material or a part thereof constitutes common general knowledge in the field related to the invention prior to the priority date of each claim appended to this application.

Claims

1. A frame structure (100) for an electrolysis device, comprising: At least first and second suppression structures (110, 120); and At least first and second support structures (210, 220) facing each other. Each support structure has two main opposing surfaces and an outer edge connected to the outer peripheral portions of the two main opposing surfaces, with a total thickness T. The first and second suppression structures are respectively located around the outer edges of the first and second support structures. ｓ Each suppression structure is composed of at least two separate segments (111, 112, 113, 114, 125, 126, 127, 128). Each segment has at least two engagable elements (010, 011, 012, 013, 020, 021, 022, 023). At least two engagable elements (011, 012) of one same segment (111) of the first suppression structure (110) face two engagable elements (021, 022) in two separate segments (125, 126) of the second suppression structure, such that the segments of the second suppression structure are oriented with respect to the segments of the first suppression structure. Frame structure.

2. The first and second support structures (210, 220) comprise housings (215, 225) suitable for accommodating electrodes of an electrolysis device and / or a separator. The housing is located on at least one of the two main opposing surfaces of each support structure. The frame structure according to claim 1.

3. At least one suppression structure is located around the outer edge of at least one support structure and covers at least 50% of the thickness T. ｓ The frame structure according to claim 1.

4. At least one damping structure is located around the outer edge of at least one support structure and covers less than 100% of the thickness T ｓ of The frame structure according to claim 1.

5. The number of support structures is more than 2, At least one damping structure (120) is located around the outer edges of at least two adjacent support structures (220, 230) The frame structure according to claim 1.

6. At least two support structures are adjacent to each other and may be separated by a gasket The frame structure according to claim 1.

7. The first and second damping structures are separated from each other by spacers (701, 702) which may be made of rubber The frame structure according to claim 1.

8. Each support structure (210, 220) has a convex portion (211, 221) along at least one of its outer peripheral edges The frame structure according to claim 1.

9. The support structure is made of a plastic material The frame structure according to claim 1.

10. The damping structure is made of a material having greater mechanical resistance than the internal support structure The frame structure according to claim 1.

11. The damping structure is made of metal, preferably steel, carbon steel or stainless steel The frame structure according to claim 1.

12. The one or more support structures are made of a high-quality engineering plastic, preferably polysulfone, polyphenylene sulfide or polyether ether ketone and may be reinforced with glass fibers The frame structure according to claim 1.

13. The frame structure is a stack of at least four suppression structures (110, 120, 130, 140) and at least four support structures (210, 220, 230, 240, 250, 260, 270, 280). The frame structure according to claim 1.

14. The at least first and second support structures are substantially circular having a maximum outer diameter D Ｆ and The first and second suppression structures are annular and are divided into a plurality of arcuate segments, Each arcuate suppression structure has an inner diameter D ｉ and an outer diameter D ｅ and D ｉ < D Ｆ < D ｅ or D Ｆ < D ｉ < D ｅ is true. The frame structure according to claim 1.

15. The engagable element is a through hole. The frame structure according to claim 1.

16. Comprising the frame structure according to any one of claims 1 to 15, At least the first support structure houses an anode, At least the second support structure houses a cathode, The anode and the cathode may be arranged opposite to each other and separated by a separator element which is a diaphragm or a membrane. Electrochemical cell.

17. Comprising a plurality of the electrochemical cells according to claim 16, The plurality of suppression structures are interconnected via tie rods that engage with at least two engagable elements of each segment. Electrolysis device.

18. Use the electrolysis device according to claim 17 for high-pressure water electrolysis.

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