Electrolytic cell with arched support members

Abstract

An electrolysis cell for chlorine-alkali or alkaline water electrolysis, comprising: two cell elements (2, 3) each defining an electrode chamber (4, 5) by providing a rear wall (6) and a side wall (7) of the electrode chamber (4, 5); electrodes (8, 9) housed in each of the electrode chambers (4, 5); a sheet-like separator (10) extending in the height direction (H) and width direction of the electrolysis cell (1), the separator (10) being inserted into a joint (11) between the two cell elements (2, 3) to provide a partition (12) between the electrode chambers (4, 5); and at least one of the electrodes (8, 9) on each rear wall (6). and a plurality of support members (13) supporting one of the electrodes (8) of the electrolysis cell (1), each of the support members (13) standing upright on the rear wall (6) and having two support portions extending in the height direction (H) of the electrolysis cell (1) and two foot portions attached to the respective support portions at an angle for planar contact with the rear wall (6), the support portions of the support members (13) arching outwardly towards the supported electrodes (8) and connected to each other by arched portions (18) providing elastic bearing surfaces (19) for the supported electrodes (8), the bearing surfaces (19) being enlarged upon inward deflection of the arched portions (18).

Description

[Background technology]

[0001] The present invention relates to an electrolysis cell according to the preamble of claim 1.

[0002] Electrolytic cells for chlor-alkali and / or alkaline water electrolysis typically contain two electrode chambers, each containing one electrode. The electrode chambers are separated from each other by a sheet separator. The electrodes in each chamber are supported by a support structure on the rear wall of the electrode chamber.

[0003] Traditionally, electrodes are spaced apart from the separator ("finite gap configuration") to prevent damage to the separator during assembly and to allow product gas to bubble freely even on the separator side of the electrode. However, to increase cell efficiency, so-called "zero gap configurations" have been developed, in which the electrodes are in contact with the separator on both sides. To reduce the risk of damaging the separator during assembly and to provide uniform contact pressure, the support structure of at least one electrode typically includes at least one elastic member in electrolysis cells with a zero gap design.

[0004] From the prior art, zero gap electrolytic cells are known which have resilient electrode support elements of different designs.

[0005] WO 2017 / 217427 describes an electrolytic cell including an elastic member disposed in a cathode chamber. The elastic member comprises a joint, a plurality of spring holders, and two spring rows, each of which is provided in the spring holder. The joint is connected to a flat electrolytic partition wall. The spring rows contact the cathode. Each spring row comprises a plurality of first flat springs. Similar elastic members with flexible tongues for supporting electrodes are known from EP 1 865 092 A, EP 1 900 851 A, and EP 1 378 589 A.

[0006] A disadvantage of known elastic flexible tongues is that the maximum surface pressure they can exert on the separator is very limited. Exceeding the maximum pressure can cause the flexible tongue to deform at its base, potentially resulting in uneven surface pressure. Furthermore, the protruding tongue may become entangled with the mesh material of the electrode, causing the tongue to deform when the cell is opened for electrode maintenance and / or recoating. Maintenance therefore requires laborious refurbishment of the flexible tongue before the cell can be reassembled.

[0007] Another type of elastic support element in an electrolysis cell is known from U.S. Patent Application Publication No. 2021 / 222306. The elastic support element includes an annular element, the axis of which is oriented in the height direction of the electrolysis cell. The annular element is at least partially plastically deformed during assembly of the cell and therefore also requires refurbishment during cell maintenance. Furthermore, the elastic support element is welded to at least one of the electrode or the rear wall, resulting in high assembly and refurbishment efforts. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2017 / 217427 [Patent Document 2] European Patent No. 1865092 [Patent Document 3] European Patent No. 1900851 [Patent Document 4] European Patent No. 1378589 [Patent Document 5] U.S. Patent Application Publication No. 2021 / 222306 Summary of the Invention

[0009] It is an object of the present invention to provide an electrolysis cell with elastic support members for electrodes that are easy to assemble and reduce manufacturing and refurbishment efforts during maintenance.

[0010] This object is achieved by an electrolysis cell according to the features of claim 1.

[0011] This provides an electrolysis cell for chlor-alkali or alkaline water electrolysis. The electrolysis cell includes two cell elements each defining an electrode chamber by providing a rear wall and side walls for the electrode chamber. The electrolysis cell further includes an electrode housed in each electrode chamber and a sheet-like separator extending in the height and width directions of the electrolysis cell. The separator is interposed at the joint between the two cell elements and provides a partition between the electrode chambers. The electrolysis cell further includes a plurality of support members supporting at least one of the electrodes on each rear wall. Each support member includes two support portions upright on the rear wall and extending in the height direction of the electrolysis cell, and two foot portions attached to the respective support portions at an angle for planar contact with the rear wall. According to the present invention, the support portions of the support members are connected to each other by arched portions that arch outward toward the supported electrodes and provide elastic bearing surfaces for the supported electrodes, the bearing surfaces being enlarged upon inward deflection of the arched portions.

[0012] The support member according to the present invention forms an arc spring. Thus, the support member is a single-piece structure that simultaneously provides a static support component through the upright support portion and a resilient support component through the deflectable arcuate portion. The functions of electrode support, current distribution, and uniform contact pressure are all provided by the support member.

[0013] Furthermore, the fact that the bearing surface of the electrode is enlarged upon inward deflection of the arched portion has advantageous effects on both the supported electrode and the support member.

[0014] When the bearing surfaces are enlarged during cell assembly, for example by providing contact pressure at the joints of the cell elements, the load acting between the electrodes and their respective rear walls is dissipated through the larger contact area of ​​the enlarged bearing surfaces. Thus, the pressure is distributed over a larger portion of the electrode's area, resulting in improved uniformity of the contact pressure between the electrode and the separator.

[0015] On the other hand, the arched portion of the support element exhibits a progressive spring characteristic due to the increased bearing surface. The progressive spring characteristic of the arched portion has the advantage that further deflection when the load increases is reduced, thereby reliably preventing plastic deformation of the support element. This reduces the effort required to remodel the support element during maintenance.

[0016] In a preferred embodiment, the foot portions are attached to the rear wall by a removable mechanical connection. When the foot portions are secured to the rear wall by a removable mechanical connection, the support members can be easily and individually attached and replaced.

[0017] Preferably, the foot portions are subdivided by recesses into latches that engage pockets provided in the rear wall. Even more preferably, the support member is secured in its mounted position by form-locking engagement of the latches in the pockets. This may be achieved, for example, by utilizing the elastic properties of the support member to deflect the foot portions during assembly, causing the latches of both foot portions to engage with their respective pockets in the rear wall. The pockets may be provided in the rear wall, preferably by corrugated metal strips. The metal strip may be intermittently secured to the rear wall, for example, by spot welding.

[0018] In a further preferred embodiment, the recesses continue into each support portion for lateral suspension of the individual latches. The continuation of the recesses into the support portions allows the latches to flex laterally independently. This simplifies attachment of the support member to the cell, as the latches can be inserted into the pockets one by one.

[0019] Preferably, the elastic bearing surface includes openings for allowing gas generated at the supported electrode to pass through. Therefore, gas generated at the electrode does not have to dissipate through the mesh-like structure of the electrode alone, but enters the portion of the electrode chamber behind the support member that is filled with electrolyte during cell operation. Furthermore, the openings improve the supply of fresh electrolyte to the electrode. Both effects contribute to improving the cell's efficiency. However, if the openings are selected too large, the stability of the support member and the mechanical resistance of the arched portion will be weakened. Therefore, the opening ratio, defined as the area of ​​the opening divided by the complete bearing surface, is preferably selected within the range of 0.6 to 0.85, more preferably within the range of 0.7 to 0.8.

[0020] In a preferred embodiment, the aperture is provided with a curved rim portion facing outward from the supported electrode, which increases the geometric moment of inertia of the arched portion, thus allowing for a larger aperture area by simultaneously enhancing the support effect of the arched portion.

[0021] In some embodiments, the foot portions of laterally adjacent support members are arranged side by side on the rear wall, which increases the contact area of ​​the support members on the rear wall and improves current distribution through the support members.

[0022] In an alternative embodiment, the foot portions of laterally adjacent support members are arranged to overlap one another on the rear wall, which has the advantage that the gap between the bearing surfaces of laterally adjacent support members is reduced so that the electrode is supported even more uniformly over its entire area.

[0023] In certain preferred embodiments, the bearing surface extends laterally on at least one side beyond the support portion by an extension portion of the support member, whereby the extension portion extends the arched portion on the opposite side of the support portion from the arched portion. Such an extension portion can be used to reduce or even close the gap between the bearing surfaces of laterally adjacent support members.

[0024] Preferably, the arched portion has an arch height and the support portion has a support height, the ratio of the arch height to the support height being in the range of 1:3 to 1:30, more preferably 1:10 to 1:20, when the arched portion is in an undeflected state. Thus, most of the space between the rear wall and the electrode is preferably bridged by the support portion, and the arch is relatively flat. This cross-sectional configuration of the support member is preferred because it provides a large bearing surface for the electrode, thereby optimizing both elastic support and uniform current distribution of the electrode.

[0025] Further advantages of the present invention will be described below with reference to the embodiments shown in the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows a schematic cross-sectional view of an electrolysis cell according to the present invention; FIG. [Figure 2A] 2 is a schematic diagram illustrating a first perspective view of the right cell element of FIG. 1 including a plurality of support members attached to the rear wall. [Figure 2B] FIG. 2B is a schematic diagram showing a second enlarged perspective view of the cell element of FIG. 2A. [Figure 3] FIG. 2C schematically shows a perspective view of a single support element according to the embodiment shown in FIGS. 1, 2A and 2B. [Figure 4A] 4 shows a schematic cross-sectional view of the support element according to FIG. 3 in the unloaded state. [Figure 4B] 4 shows a schematic cross-sectional view of the support element according to FIG. 3 in a loaded state. [Figure 5A] 1A-1C show schematic cross-sectional views of different configurations of a support member according to the invention; [Figure 5B] 1A-1C show schematic cross-sectional views of different configurations of a support member according to the invention; [Figure 5C] 1A-1C show schematic cross-sectional views of different configurations of a support member according to the invention; [Figure 5D] 1A-1C show schematic cross-sectional views of different configurations of a support member according to the invention; [Figure 5E] 1A-1C show schematic cross-sectional views of different configurations of a support member according to the invention; [Figure 6] FIG. 10 schematically illustrates a perspective view of a support member according to another embodiment of the present invention. [Figure 7] 7A and 7B show schematic cross-sectional views of the support member according to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] In the drawings, like parts are identified by the same reference numerals throughout and therefore will be generally described and referenced only once.

[0028] Figure 1 shows a cross-sectional view of an electrolysis cell 1 for chlor-alkali or alkaline water electrolysis according to the invention. The electrolysis cell 1 comprises two cell elements 2, 3 each defining an electrode chamber 4, 5 by providing a rear wall 6 and a side wall 7 of the electrode chambers 4, 5 and electrodes 8, 9 housed in each of the electrode chambers 4, 5.

[0029] Figures 2A, 2B and 3 show in perspective views further details of the internal structure of the electrolysis cell 1 according to Figure 1. The structure of the cell 1 will therefore be explained in more detail below with reference to Figures 1 to 3.

[0030] The cell 1 further includes a sheet-like separator 10 extending in the height direction H and width direction W of the electrolysis cell 1. The separator 10 is interposed between the junction 11 of the two cell elements 2, 3 and provides a partition 12 between the electrode chambers 4, 5. A plurality of support members 13 are provided within the cell 1, supporting one of the electrodes 8 on each rear wall 6. Each support member 13 includes two support portions 14, 15 that stand upright on the rear wall 6 and extend in the height direction H of the electrolysis cell 1, and two foot portions 16, 17 that are inclined and attached to the respective support portions 14, 15 for planar contact with the rear wall 6. According to the present invention, the support portions 14, 15 of the support member 13 are connected to each other by an arched portion 18. The arched portion 18 arches outward toward the supported electrode 8 and provides a resilient bearing surface 19 for the supported electrode 8. Inward deflection of the arched portions 18 enlarges the bearing surface 19.

[0031] During operation, one of the electrodes 8, 9 acts as the anode for electrolysis, while the other acts as the cathode. Because different chemical products are obtained at the anode (chlorine, oxygen) and cathode (hydrogen), the electrode chambers 4, 5 may be designed differently. In particular, more severe conditions typically prevail in the anode chamber due to the oxidizing effect of chlorine or oxygen produced in chlor-alkali and alkaline water electrolysis, respectively. The elastic support member according to the present invention can generally be used in both the anode and / or cathode chambers.

[0032] As best seen in the figures, as shown in Figures 2A and 2B, foot portions 16, 17 may be attached to rear wall 6 by a removable mechanical connection. In particular, foot portions 16, 17 may be subdivided by recesses 20 into latches 21 (see Figure 3) that engage pockets 22 provided in rear wall 6. Pockets 22 may be provided in rear wall 6 by corrugated metal strips 23 intermittently secured to rear wall 6 by spot welding.

[0033] The structure of the support member 13 will be described in more detail with reference to FIG. 3 . The support portions 14 and 15, together with the arched portion 18 and the rear wall 6, form a hollow channel in the height direction H of the cell for unimpeded passage of electrolyte and / or gases produced at the supported electrode 8. Along the height direction H, the support member 13 can be subdivided into a plurality of individual arches 27, e.g., seven arches 27 as shown in FIG. 3 . These individual arches are preferably formed by recesses 20 continuing into the respective support portions 14 and 15, providing lateral support for the individual latches 27 that form the foot portions of the individual arches 21, 16 and 17. The individual arches 27 may be connected to each other within the region of the support portions 14 and 15 by bridges 28, as shown in FIG. 3 . Alternatively, the recesses can continue into the arched portions 18, such that the individual arches 18 are connected to each other only within the region of the arched portions 27.

[0034] Preferably, the elastic bearing surface 19 is provided with openings 24 for the passage of gas produced at the supported electrode 8. As shown in Figure 3, the openings 24 may be slit-like openings, preferably extending in the width direction W of the cell 1. Preferably, multiple openings 24 are provided within each individual arch 27.

[0035] The aperture ratio of the aperture 24 to the complete bearing surface 19 (including the aperture 24) may be in the range of 0.2 to 0.45, more particularly in the range of 0.25 to 0.35. As shown in Figure 3, the aperture 24 is preferably provided with a bent rim portion 25 facing away from the supported electrode 8.

[0036] The support portions 16, 17 may include notches 29. The notches 29 allow for improved flow of electrolyte along the width direction W of the cell 1 and reduce the amount of material required to construct the support member 13.

[0037] The support member 13 is preferably made of a metallic material, particularly preferably made of nickel or titanium.

[0038] In Figure 4A, support member 13 is shown in an undeflected, unloaded state. Arched portion 18 has an arch height h1, and support portions 14, 15 have a support height h2. In the undeflected state, the ratio of arch height h1 to support height h2 is in the range of 1:3 to 1:30, particularly in the range of 1:3 to 1:6. The total height of the support member is designated h3.

[0039] When an electrode is placed on arched portion 18 in an unloaded, undeflected state, resilient bearing surface 19 is centered at the top of the arch and has an unloaded support width w1. In FIG. 4B, support member 13 is shown under load. As load-induced inward deflection of arched portion 18 occurs, bearing surface 19 increases, resulting in an increased support width w2 under load. Support width w2 under load is preferably at least 50%, and even more preferably at least 75%, of the overall width w3 of arched portion 18. Support width w2 under load can reach up to 100% of the overall width w3 of arched portion 18.

[0040] 5A to 5E show in cross-section five variants of the arrangement of several laterally adjacent support members 13 on the rear wall 6 of an electrolysis cell according to the invention.

[0041] 5A shows support member 13 with outwardly bent foot portions 16, 17. The foot portions 16, 17 are arranged side-by-side and introduced into pockets formed under metal strip 23. This arrangement provides a large contact area with rear wall 6, but also a relatively large unsupported gap 30 of the electrode between the arched portions 18 of adjacent support members 13.

[0042] 5B, the leg portions 17, 16 of the support members 13 adjacent to each other on the left and right sides of the rear wall 6 can be arranged to overlap each other. This reduces the width of the stripes 23 and the width of the gap 30.

[0043] Another configuration is shown in Figure 5C. By bending the foot portions 16, 17 to the same side, the gap 30 between the arched portions 18 of adjacent support members 13 can be reduced to the width of one of the foot portions 16, 17. The foot portions 16, 17 are introduced into the pockets under the metal stripes 23 from one side. As shown in Figure 5C, both or only one of the foot portions 16, 17 may be fixed to the rear wall 6.

[0044] 5D shows a configuration with minimal gap 30. Both foot portions 16, 17 are bent inward so that support portions 14, 15 of adjacent support members 13 are directly adjacent to one another. This configuration has a relatively high assembly labor because twice the number of metal stripes 23 are required.

[0045] 5E illustrates an arrangement in which extensions 26 of support member 13 cause bearing surfaces 19 to extend laterally on either side beyond support portions 14, 15. In this manner, extensions 26 are configured to support electrodes in gaps 30 between adjacent support members 13.

[0046] 6 and 7 show another embodiment of a support member 13 according to the present invention. The bearing surface 19 in FIG. 6 is not subdivided into a plurality of individual arches, but is instead configured as a regular grid. The openings 24 are therefore evenly spaced across the entire bearing surface 19. This has the positive effect of uniforming gas discharge and electrolyte exchange across the electrodes 8 through the openings 24 in the bearing surface 19. Furthermore, the surface pressure on the bearing surface 19 is uniformed by the regular structure.

[0047] Another difference compared to the embodiment of Figure 3 is the larger open area ratio of the openings 24 to the complete bearing surface 19, i.e., in the range of 0.6 to 0.85, and particularly in the range of 0.7 to 0.8. This significantly larger open area ratio also facilitates electrolyte and gas exchange through the bearing surface 19 while still providing sufficient support for the electrode 8.

[0048] The embodiment of Figure 1, Figures 6 and 7 further features a particularly flat arched portion 18. The ratio of arch height h1 to support height h2 (see Figure 7) is in the range of 1:3 to 1:30, in particular 1:10 to 1:20, when arched portion 18 is in an undeflected state. It has been found that a fairly flat arched portion 18 helps to provide a uniform surface pressure across the width W of the support element.

[0049] In all other respects, the description of the embodiment shown in FIGS. 1-4 also applies to the embodiment shown in FIGS. [Explanation of symbols]

[0050] 1 electrolysis cell 2, 3 cell elements 4, 5 Electrode chamber 6 Back wall 7 side wall 8, 9 electrodes 10 Sheet separator 11 Joint 12 Bulkhead 13 Support member 14, 15 Support part 16, 17 foot part 18 Arched section 19 Elastic bearing surface 20 recess 21 Latch 22 pockets 23 Metal Strip 24 Opening 25 Rim part 26 Extension 27 Arch 28 Bridge 29 Notch 30 Gap H Height direction h1 Arch height h2 Support height h3 Overall height of support member W width direction w1 No-load support width w2 Load support width w3 Width of arched part

Claims

1. 1. An electrolysis cell for chlor-alkali or alkaline water electrolysis, comprising: two cell elements (2, 3) each defining an electrode chamber (4, 5) by providing a rear wall (6) and a side wall (7) of said electrode chamber; an electrode (8, 9) housed in each of said electrode chambers (4, 5); a sheet-like separator (10) extending in the height direction (H) and width direction (W) of the electrolysis cell (1), inserted into the joint (11) between the two cell elements (2, 3) to provide a partition (12) between the electrode chambers (4, 5); and a plurality of support members (13) for supporting at least one of the electrodes (8, 9) on the respective rear walls (6), each of the support members (13) comprising: two support parts (14, 15) standing upright on the rear wall (6) and extending in the height direction (H) of the electrolysis cell (1); two foot portions (16, 17) mounted on the respective support portions (14; 15) at an angle for planar contact with the rear wall (6); the support portions (14, 15) of the support member (13) arch outwardly toward the supported electrode (8) and are connected to one another by an arched portion (18) that provides a resilient bearing surface (19) for the supported electrode (8), the bearing surface (19) being enlarged upon inward deflection of the arched portion (18); An electrolytic cell characterized by:

2. 2. An electrolysis cell according to claim 1, characterized in that the foot portions (16, 17) are attached to the rear wall (6) by means of a removable mechanical connection.

3. 3. An electrolytic cell according to claim 1 or 2, characterized in that the foot portions (16, 17) are subdivided by recesses (20) into latches (21) which engage in pockets (22) provided in the rear wall (6).

4. 4. The electrolysis cell according to claim 3, characterized in that the pockets (22) are provided in the rear wall (6) by corrugated metal strips (23) intermittently fixed to the rear wall (6) by spot welding.

5. 5. An electrolytic cell according to claim 3 or 4, characterized in that the recesses (20) are continuous in the respective support parts (14, 15) for the lateral suspension of the individual latches (21).

6. 6. An electrolysis cell according to any one of claims 1 to 5, characterized in that the elastic bearing surface (19) comprises openings (24) for the passage of gases produced at the supported electrodes (8).

7. 7. An electrolytic cell according to claim 6, characterized in that the aperture ratio of the openings (24) to the complete bearing surface (19) is in the range of 0.6 to 0.

85.

8. 8. An electrolytic cell according to claim 7, characterized in that the opening ratio of the openings (24) to the complete bearing surface (19) is in the range of 0.7 to 0.

8.

9. 9. An electrolytic cell according to any one of claims 6 to 8, characterized in that the opening (24) is provided with a curved rim portion (25) facing away from the supported electrode (8).

10. 10. An electrolysis cell according to any one of claims 1 to 9, characterized in that the foot portions (17, 16) of laterally adjacent support members (13) are arranged one on top of the other on the rear wall (6).

11. 11. An electrolytic cell according to any one of claims 1 to 10, characterized in that the bearing surface (19) extends laterally at least on one side beyond the support portions (14, 15) by an extension (26) of the support member (13).

12. 12. An electrolysis cell according to any one of claims 1 to 11, characterized in that the arched portion (18) has an arch height (h1) and the support portions (14, 15) have a support height (h2), the ratio of the arch height (h1) to the support height (h2) being in the range of 1:3 to 1:30 in an undeflected state of the arched portion (18).

13. 13. The electrolysis cell according to claim 12, characterized in that the ratio of the arch height (h1) to the support height (h2) is in the range of 1:10 to 1:20 in the undeflected state of the arched portion (18).

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