Frame structure of an electrolysis apparatus

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] This invention relates to the field of frame structures for electrolytic apparatuses. [Background technology]

[0002] Depending on the industrial application, electrolysis equipment may operate at various pressures, and therefore, it is required to withstand mechanical stress not only on the overall structure but also on its individual components. Pressure conditions are determined by the chemistry, components, dimensions, and the industry in which it is used. Examples of high-pressure electrolysis equipment can be found, for example, in the fields of proton exchange membrane (PEM) electrolysis equipment and alkaline water electrolysis (AWE), where the operating pressure exceeds 5 bar.

[0003] Previously, for example, the cell frames of high-pressure electrolytic devices used in AWE applications were all made of carbon steel or stainless steel, which provides excellent mechanical integrity. However, the corrosion rate of these metals when immersed in strong alkaline solutions negatively impacts not only the lifespan of the electrolytic device but also its overall performance. Corrosion of carbon steel or stainless steel negatively affects the purity of the electrolyte, obstructs the electrolyte flow, and causes sludge formation, which can lead to pressure loss and safety problems.

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

[0005] Engineering plastics can be used to manufacture cell frames for small pressurized electrolytic apparatuses where mechanical stress and deformation are limited. However, in large and / or high-pressure electrolytic apparatuses, cell frames made from these materials require considerable thickness to withstand mechanical stress and maintain acceptable mechanical deformation. This approach is disadvantageous because it significantly increases the cost, size, and weight of the electrolytic apparatus.

[0006] The object of the present invention is to provide a frame structure for an electrolysis apparatus that can withstand internal pressure regardless of its dimensions or the industry in which it is used, while limiting the cost of the cell frame, the dimensions of its components, and its weight, and combining the chemical 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 electrolysis apparatus having a frame structure according to the present invention, particularly for use in high-pressure water electrolysis applications. [Overview of the Initiative]

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

[0009] The frame structure of the present invention is (i) at least first and second restraining structures, (ii) at least first and second support structures, It is equipped with.

[0010] Each support structure typically has two main opposing surfaces and a total thickness T s It has an outer edge.

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

[0012] The first and second support structures are positioned opposite each other, even when other elements are interposed between them, so that their main opposing surfaces are essentially parallel to each other.

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

[0014] The housing can be positioned on at least one of the two main opposing surfaces of each support structure. The housing may be a free space with an appropriate outer diameter around its edges to properly hold electrodes and / or other elements. The housing may be a through-hole to expose the electrode surface and facilitate electrochemical reactions on both sides.

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

[0016] For less demanding electrochemical applications, polypropylene or other less expensive plastic support structures are perfectly adequate.

[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 piezolytic 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 inner 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 materials that are mechanically more robust than the support structure and have 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 compatible corrosion-resistant materials), the suppression structure does not contact the electrolyte and preferably functions as a mechanical reinforcement of the support structure under pressure. To further reduce the possibility of deformation of the inner support structure and keep the suppression structure away from the electrolyte, the suppression structure may be advantageously 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 are preferably arranged substantially adjacent to each other and continuously along the edge of the support structure.

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

[0024] Since each suppression 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 engaging elements in the same segment of the first suppression structure face two engaging elements in two separate segments of the second suppression structure, and the segments of the first and second suppression structures are oriented with respect to each other.

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

[0026] The segmented design of the external suppression 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 suppression 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 suppression structure should be.

[0028] When the suppression 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 an edge thickness T s The outer edge of the support structure overlaps with the width of less than 100%, i.e., the edge is not completely covered, and the possibility of direct contact between adjacent restraint structures is avoided. The restraint structures may be made of materials unsuitable for this effect, thereby preventing the restraint structures from releasing clamping forces from each other. Appropriate spacers may be inserted between the restraint structures. Furthermore, leaving some space between adjacent restraint structures ensures room for inserting a useful device for monitoring cell voltage parameters.

[0030] According to another embodiment, if the number of support structures exceeds two, at least one restraint structure may be simultaneously positioned around the outer edges of at least two adjacent support structures. This reduces the number of parts required to assemble the electrolysis apparatus and facilitates the installation of the electrolysis apparatus.

[0031] In the frame structure according to the present invention, at least two support structures may be arranged adjacent to each other and optionally separated by a gasket. The gasket may be housed in a suitable groove on the main surface of the support structure. In other embodiments, the gasket may be located 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 restraining structures are separated from each other by spacers (optionally made of rubber). This ensures that the correct relative positions of the elements are maintained. Furthermore, it is ensured that the pressure from the clamping system of the electrolysis apparatus 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 projection along at least one of its outer edges, facilitating the accommodation of each restraint structure within the resulting corner.

[0034] The suppression structure according to the present invention is preferably made of a material with high mechanical resistance, such as a metal, for the internal support structure. More preferably, they are made of steel, particularly 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 that prevents corrosion.

[0035] All of the above materials impart sufficient robustness to the external suppression structure to effectively cancel out the radial forces experienced 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 of 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 such that D i < D F < D e or D F < D i < D e < D. Depending on whether there are protrusions on 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 apparatus comprising a plurality of electrochemical cells, each having the aforementioned frame structure, and the restraint structures are interconnected via tie rods that engage with at least two engageable elements (preferably through-holes) of each segment.

[0040] In a further embodiment of the electrolysis apparatus according to the present invention, each frame structure advantageously includes two internal support structures positioned between the first and second restraint structures, the two additional support structures being positioned outward relative to the peripheral restraint structures and closed by two opposite end flanges.

[0041] In the latter case, it is preferable that the pressure along the axial direction of the electrolysis apparatus (i.e., the direction perpendicular to the electrodes) does not come into direct contact with the suppression structure in order to avoid the pressure 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 electrolysis apparatus described above for high-pressure (>5 bar) water electrolysis, preferably alkaline water electrolysis.

[0043] Several embodiments of the present invention are described below by reference to the accompanying drawings, but their purpose is solely to illustrate the relative arrangement of various elements related to the 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, and z are used in the same manner throughout all the figures. The xy plane is substantially parallel to the two main planes of the internal support structure, while z is perpendicular to such planes and identifies the main longitudinal axis of the electrolysis apparatus according to the present invention. [Brief explanation of the drawing]

[0044] [Figure 1] Figure 1 is a schematic exploded view of the frame structure (100) according to the present invention.

[0045] The frame structure consists of a first restraint structure (110) and a second restraint structure (120), a first support structure (210) and a second support structure (220). Their shapes are designed so that the adhesion between the restraint and support structures is substantially uniform when the restraint structures are wrapped around the outer edges of the support structures, covering all or part of the width of the support structures along the Z-direction. The first restraint structure consists of four identical and distinct segments (111, 112, 113, 114). In general, the segmentation of the restraint structures does not have to be identical, and the segments of individual restraint structures may be different from each other. In this particular case, as can be seen in the figure, the second restraint structure, like the first restraint structure, consists of four identical and distinct segments (125, 126, 127, 128). All segments are provided with four holes as engageable elements. The support structures (210, 220) are provided with housings (215, 225) for electrodes and other optional elements necessary for the cell's operation. Note that the use of identical restraint structures and segmentation may simplify the assembly of parts and the management of spare parts. [Figure 2] Figure 2 shows the relative arrangement of segments and corresponding engageable elements in the first and second restraint structures shown in Figure 1.

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

[0047] Figure 2(b) shows how the first and second restraint structures (110, 120) are positioned relative to the same set of coordinates in the xy-plane. The second restraint structure (120) is identical to the first restraint structure but rotated by an angle (45° in this particular example), so that the points of discontinuity (01, 02, 03, 04, 05, 06, 07, 08) in the first and second restraint structures, i.e., where the restraint structures are divided, are offset from each other. This allows at least two engageable elements (011, 012) of one identical segment (111) of the first restraint structure (110) to face two engageable elements (021, 022) located on two separate segments (125, 126) of the second restraint structure. When an engaging means, such as a tie rod, connects the respective engageable elements of the two restraint structures, the resulting device becomes mechanically stable. Similar effects can be obtained when the suppression structure is in the shape of a continuous ring, but the amount of scrap and package dimensions significantly increase manufacturing and transportation costs. In this figure, the segments within each suppression structure are arranged substantially adjacently and continuously, optimizing the effect on radial pressure, i.e., the pressure in the xy plane acting during cell operation. [Figure 3] Figure 3 is a schematic exploded view of specific elements of the electrolysis apparatus according to the present invention.

[0048] Two restraint structures (110, 120) are shown. The first restraint structure (110) is suitable for wrapping around both support structures (200) and (210). Support structure (200) is suitable for housing a bipolar element (400) (with a current collector and anode welded to its surface). Support structure (210) is suitable for housing a cathode (600) and an elastic element (300). A separator (500) is sandwiched between the anode surface welded to the bipolar element (400) and the cathode (600). Similarly, the second restraint structure (120) is suitable for wrapping around both support structures (220) and (230). Support structure (220) is suitable for housing a bipolar element (450) (with a current collector and anode welded to its surface). The support structure (230) is suitable for housing the cathode (650) and the 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 restraint structure (120) are rotated 45° in the xy-plane relative to the corresponding segments (111, 112, 113, 114) of the first restraint structure (110). [Figure 4] Figure 4 shows two sections of an electrolysis apparatus according to the present invention, including a stack of multiple electrolytic cells.

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

[0051] In this embodiment, each restraint structure covers two support structures at once (for example, (120) covers (220, 220)). The support structures have protrusions (221, 222, 223) that create recessed spaces for accommodating the restraint structures. In this embodiment, the individual thickness T of the restraint structures c It is approximately 1.6T S Equal to the individual thickness T of the support structure. s It covers approximately 80% of the area.

[0052] The restraint structures are separated from each other by spacers (701, 702, 703). The restraint structures deal with 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 apparatus be assembled so that the restraint structures, which may be advantageously made of steel, do not come into direct contact with the metal terminal flanges. [Figure 5] Figure 5 is the same figure as Figure 2(b) but with a rectangular geometry instead of a circular one, showing the first and second suppression structures (110, 120) positioned relative to the same set of coordinates in the xy-plane.

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

[0054] In the description and claims of this application, the word “comprise” and its variations “comprising” and “comprises” do not preclude the existence of other additional elements, components, or stages.

[0055] The descriptions of documents, certificates, materials, apparatus, articles, etc., contained herein are provided solely for the purpose of explaining the background of the present invention, and these materials, or any part thereof, should not be understood to constitute general knowledge in the art related to the invention prior to the priority date of each claim attached to this application.

Claims

1. A frame structure (100) for an electrolysis apparatus, At least two inhibitory structures (110, 120), At least two support structures (210, 220) facing each other, Equipped with, The two aforementioned restraining structures are made of steel. The two support structures mentioned above are made of engineering plastic. Each of the two support structures has two main opposing surfaces and an outer edge with a total thickness Ts that connects to the outer peripheral edges of the two main opposing surfaces. The two restraining structures are each located around the outer edge of the two support structures, Each of the two suppression structures is composed of at least two separation segments (111, 112, 113, 114, 125, 126, 127, 128), Each of the at least two separation segments comprises at least two engageable elements (010, 011, 012, 013, 020, 021, 022, 023), The separation segment of the other suppression structure is oriented relative to the separation segment of the first suppression structure such that at least two engageable elements (011, 012) of one separation segment (111) of one suppression structure (110) of the two suppression structures face two engageable elements (021, 022) of two separation segments (125, 126) of the other suppression structure of the two suppression structures. Frame structure.

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

3. At least one of the at least two restraining structures is located around the outer edge of at least one of the at least two support structures and covers at least 50% of the thickness Ts. The frame structure according to claim 1.

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

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

6. The 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 two restraining structures are separated from each other by spacers (701, 702). The frame structure according to claim 1.

8. The spacer is made of rubber. The frame structure according to claim 7.

9. Each of the at least two support structures (210, 220) has a protrusion (211, 221) along at least one of its outer edges. The frame structure according to claim 1.

10. The at least two restraining structures are made of a material having greater mechanical resistance than the at least two support structures. The frame structure according to claim 1.

11. The at least two restraining structures are made of carbon steel or stainless steel. The frame structure according to claim 1.

12. The at least two support structures are made from polysulfone, polyphenylene sulfide, or polyether ether ketone. The frame structure according to claim 1.

13. The at least two support structures are reinforced with glass fibers. The frame structure according to claim 12.

14. The frame structure is a stack of at least four restraining 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.

15. The at least two support structures are circular and have a maximum outer diameter DF. The two aforementioned restraining structures are annular and divided into multiple arc-shaped segments. Each of the plurality of arc-shaped segments has an inner diameter Di and an outer diameter De. Di < DF < De or DF < Di < De The frame structure according to claim 1.

16. The engageable element is a through-hole. The frame structure according to claim 1.

17. The frame structure comprises the frame structure described in any one of claims 1 to 16, One of the at least two support structures accommodates the anode. The other support structure of the at least two support structures accommodates the cathode. The anode and cathode may be positioned opposite each other and separated by a separator element, which is a diaphragm or membrane. Electrochemical cell.

18. A plurality of electrochemical cells as described in claim 17, Multiple restraint structures are interconnected via tie rods that engage with at least two engageable elements of each segment. Electrolysis apparatus.

19. A method comprising using the electrolysis apparatus described in claim 18 for high-pressure water electrolysis at an operating pressure exceeding 5 bar.

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