Structural assembly of cells for an electrolytic cell, electrolytic cell, and method for manufacturing such structural assembly

Abstract

The present invention relates to a structural assembly of a staple-type electrolytic cell having a plurality of cells stacked in the axial direction, comprising a press frame device and a membrane device abutting the seat surface and sandwiched between the main frame and the press frame device in the axial direction, wherein a common axial extension amount of the membrane device and the press frame device in an assembled state is set by the axial distance between the mounting surface and the seat surface and is reached by the axial pressure applied in the assembly process, and a reduction in the common axial extension amount is mainly brought about by a reduction in the axial extension amount of the press frame device.

Description

Technical Field

[0001] The present invention relates to the field of staple-type electrolytic cells having a plurality of axially stacked cells, and more particularly to the cell structure assembly of such electrolytic cells, the structure assembly including a main frame having a mounting surface and a sheet surface, a pressurizing frame device, and a membrane device that abuts against the sheet surface and is sandwiched axially between the main frame and the pressurizing frame device. The common axial extent in the assembled state of the membrane device and the pressurizing frame device is set by the axial distance between the sheet surface and the mounting surface and is achieved by the axial pressure applied in the assembly process.

Background Art

[0002] The structure assembly of an electrolytic cell is known, for example, from German Patent Application Publication No. 10 2014 010 813. In this document, an inner reinforcing ring for the main frame is proposed, but such reinforcement is not essential for the present invention, and for the main frame, a main frame with or without reinforcement or a main frame with outer reinforcement is envisaged.

[0003] Of course, the membrane (device) needs to be fixed to the main frame. For this purpose, several methods have been used in this part. These range from screwing the membrane with appropriate screws with washers to seal arrangements against the main frame. Other methods involve sandwiching the membrane between a radially inward protruding portion of the main frame and a counter-frame portion, thereby distributing the clamping force more uniformly over the entire membrane, and the counter-frame is fixed to the main frame, for example, by screws.

[0004] In further technology, the tightening force provided by screws is replaced by surface pressure applied during assembly (acting against the elastic reaction force of the seal to properly seal the cell paths between cells and adjacent cells). Thus, the rigid counterframe functions as a pressure frame for compressing the membrane within the clamping area during the assembly process. Of course, the axial dimensions of the pressure frame are adjusted so that the assembly process is possible by maintaining sufficient clamping pressure in the assembled state.

[0005] The object of the present invention is to provide a structural assembly like the one initially described, which is improved in terms of the combination of satisfactory ease of manufacture and the operational reliability of an electrolytic cell having such a structural assembly. [Overview of the project]

[0006] For this purpose, the present invention provides a structural assembly as initially introduced, which is essentially characterized in that the reduction in common axial extension is mainly brought about by a reduction in the axial extension of the pressurized frame device.

[0007] In other words, the inventors have found a hidden risk in conventional structural assemblies including a pressurized frame, where machining tolerances for the main frame and pressurized frame may not be fully met, or may be set so close that there is a risk of not being fully met, or may be met for a single part, but the total axial dimensions may not be ideal. Such defects may remain undetected during the assembly process, or may even be undetectable during the assembly process, but can lead to insufficient residual pressure after assembly, which may result in defects in the operation of the electrolytic cell.

[0008] Furthermore, the inventors have found that such problems can be reduced or avoided by a characteristic feature of the present invention, which effectively shifts the tolerances for a properly assembled cell structure from, at least in part, consideration of the (static) axial dimensions of the pressurizing frame to a mode of (dynamic) deformation of the pressurizing frame having a reduction in the axial extension (effective deformation) of the pressurizing frame device, caused by axial pressure applied as an additional reservoir for considering the tolerances of a single part of the structural assembly. "Mainly" refers to the percentage of the reduction in axial extension caused by the pressurizing frame. However, there may also be other additional means for fixing in the circumferential direction, but preferably 180° or more, more preferably 240° or more, and particularly 300° or more around the entire circumference, with respect to the reduction in axial extension caused by the pressurizing frame device. The membrane device includes, and in particular may consist of, membranes of cells (i.e., the device may be merely a membrane).

[0009] In preferred embodiments, the reduction in the main axial extension is also primarily due to the geometric shape of the pressurizing frame assembly. That is, while material properties such as the Young's modulus of the material can generally be addressed, the pressurizing frame assembly is made more elastic by its geometric shape, and in particular its elasticity to axial pressure is increased. In this relationship, it is preferable that the surface area of ​​the cross-section of the pressurizing frame assembly varies across its axially extended portion and is particularly small in the intermediate axial zone. That is, the pressurizing frame is not composed of a mass defined by its external shape, but rather has cavities, recesses, and / or notches that provide a geometric shape that increases elasticity to axial pressure.

[0010] In a preferred embodiment, the geometric features of the geometric shape may include a U-shaped or V-shaped axial cross-section. However, other types of geometric shapes can also be considered, such as those that provide the pressurizing frame characteristics of a spring according to some types of spring mechanisms, such as clamp springs, torsion springs, or wave springs. That is, elasticity that bends the beam or moves a lever-like portion against torque can be incorporated into the geometric shape of the pressurizing frame device.

[0011] While a pressurized frame assembly can be fabricated from a single, integrated part, the pressurized frame device preferably comprises multiple segments in the circumferential direction, particularly an annular and / or circumferentially closed topology. It should be understood that such annular topology provides shape and may include multiple annular segments corresponding to the segments of the pressurized frame device in the circumferential direction. This facilitates the manufacture of larger electrolytic cells, particularly those with a greater effective area.

[0012] In a more preferred embodiment, the axial stress (axial pressure) on the membrane / membrane apparatus is partially, primarily, or entirely supplied by an elastic restoring force to provide sufficient holding force to retain the membrane against the main frame in the assembled state. The axial stress is 6 N / mm 2 Larger, preferably 9 N / mm 2 Larger, especially 12 N / mm 2 It can be larger.

[0013] In a more preferred embodiment, the pressurized frame device may have a release cavity to reduce the amount of circumferential elongation while the amount of axial extension is decreasing. This allows for partial suppression of deformation due to circumferential forces and reduces adverse effects on seating stability.

[0014] In a more preferred embodiment, the axial (compressive) deformation of the film is less than 8%, preferably less than 6%, particularly less than 4%, and / or less than 0.1 mm, preferably less than 0.07 mm, particularly less than 0.05 mm.

[0015] This can be achieved by matching the elasticity due to the geometric shape of the pressurizing frame to the Young's modulus of the membrane, so that the reduction in the axial extension of the composite system is determined by what is caused by the geometric shape of the pressurizing frame. This effectively provides an overall reduction in the axial extension of the system through the reduction in the axial extension of the pressurizing frame, and as a result, even non-flexible membranes (diaphragms) can be used. This also increases the versatility when constructing a single component of a structural assembly, and in particular, enables rigid membranes (diaphragms).

[0016] Please understand that the contact of the membrane (diaphragm) with the sheet surface can be direct or indirect via an intermediate component (however, direct contact is preferred).

[0017] In this regard, the effective Young's modulus of the pressurized frame device in the axial direction is preferably at least 1.1 times, preferably at least 1.2 times, and particularly at least 1.3 times lower than the Young's modulus of the membrane assembly in the axial direction. The effective Young's modulus of the pressurized frame is not that of the pressurized frame material, but is determined by the reduction in axial extension, including the effect of the geometric shape of the pressurized frame device in the axial pressure applied during the assembly process.

[0018] In a more preferred embodiment, the membrane / membrane device has positioning holes that match positioning pins on the sheet surface. This provides more accurate positioning in the extending plane perpendicular to the stapling direction during the assembly process.

[0019] In a more preferred embodiment, elements of a pressurized frame assembly can be joined via hinge connections to form a circumferential chain. Axial pins for this connection can be formed on the chain elements and / or by positioning pins on the sheet surface.

[0020] The pressure providing residual stress in the assembled state is preferably caused (only) by an external axial pressure applied during the assembly process (with a predetermined relaxed axial dimension of the combined arrangement) in which one cell is stacked on top of the other under axial pressure, but it should be understood that this is not limited to providing only such a single assembly pressure. For example, additional fastenings can be made, for example, by screws, near the intersection of one pressurized frame segment to another. In this case, it is preferable to decouple such additional fastenings from consideration of axial pressure by, for example, ensuring that the total axial extension of the portion of the additional fastening is in any case less than the set axial distance between the sheet surface and the mounting surface.

[0021] Furthermore, the present invention also provides a staple-type electrolytic cell having a plurality of cells stacked in the axial direction, one or more of which, in particular all of which have a structural assembly according to any of the embodiments described above.

[0022] The present invention also provides a pressurized frame device for a structural assembly according to any of the above embodiments, in particular, wherein the reduction in its axial extension is mainly caused by its geometric shape, i.e., the elasticity due to its geometric shape.

[0023] Generally, with respect to the reduction in axial extension, it is not required that the deformation of the pressurized frame device be solely elastic without the influence of plastic deformation. However, the elastic contribution of the deformation should preferably be dominant, allowing the structural assembly to be disassembled and reassembled, thereby providing sufficient holding force in the reassembled state.

[0024] Furthermore, the present invention provides a method for manufacturing a pressure frame device according to the above-described aspects, particularly including the step of providing an outer shape of a pressure frame component by casting or injection molding, and the step of providing a geometric shape that provides elasticity according to the shape within a molding step and / or an additional material removal step.

[0025] Furthermore, the present invention provides a method for manufacturing a structural assembly according to any of these aspects, the method including the step of manufacturing a main frame, and the step of manufacturing a pressure frame device according to the axial distance between the mounting surface and the sheet surface of the main frame, particularly according to the axial extent of the membrane / membrane device, such that a decrease in the common axial extent is mainly brought about by a decrease in the axial extent of the pressure frame device.

[0026] Furthermore, the present invention provides a method for assembling a staple-type electrolytic cell, the method including the step of preparing a plurality of electrolytic cell units, the step of assembling the units between two end plates of the electrolytic cell by applying axial pressure, and thereby the step of reducing the common axial extent of the pressure frame device and the membrane in the axial direction, where the decrease in the common axial extent is mainly brought about by a decrease in the axial extent of the pressure frame device in the axial direction.

[0027] The advantages of these methods can be obtained from the above and subsequent descriptions, and it can be understood that they facilitate manufacturing from the perspective that the intersections are not so severe, particularly enabling the manufacture of individual components of the structural assembly independently of each other, particularly at separate manufacturing locations.

[0028] Further features, details, and advantages of the present invention can be obtained from the subsequent description with reference to the accompanying drawings.

Brief Description of the Drawings

[0029] [Figure 1] FIG. 1 schematically shows a perspective view of a structural assembly of an electrolytic cell unit. [Figure 2]Figure 2 shows an axial cross-section of the structural assembly in Figure 1, assembled together with the pressurized frame device. [Figure 3] Figure 3 shows an axial cross-section of the pressurized frame device in a relaxed state. [Figure 4] Figure 4 shows a perspective view of a part of the pressurized frame device. [Figure 5] Figure 5 shows another axial cross-section of an optional additional local fixation. [Figure 6] Figure 6 shows the chain of pressurized frame elements. [Modes for carrying out the invention]

[0030] In the perspective view of Figure 1, the main frame 10 is schematically depicted, having essentially an annular outer shape and an interior 50, for clarity. The outer boundary is provided with a reinforcing section 11, which may be formed, for example, by windings of reinforcing material wrapped around the main frame 10, to provide further stability against radial pressure during the operation of the electrolytic cell. The interior space 50 is limited by internal boundaries 53, 54, which are formed in steps (Figure 2) to form a sheet surface 57 on the extending surface perpendicular to the staple axis of the electrolytic cell. Furthermore, the frame 10 has several axial through-holes 12 and connections therefrom to the interior 50 of the manifold, which help to transport the electrolyte into the half-cells 51, 52 of the interior space 50 divided by the membrane 20.

[0031] The membrane 20 is laid on the sheet surface 57 and sandwiched between the sheet surface 57 and the radially protruding portion of the main frame 10 having the pressure frame device 30. In this embodiment, the pressure frame device 30 is shown as being formed integrally as a whole, but it may include a number of circumferentially adjacent pressure frame components, thereby forming a 360° arrangement of the annular topology.

[0032] Thus, the membrane 20 is sandwiched between the sheet surface 57 of the main frame 10 and the lower side 37 of the pressure frame. Although not shown, an additional seal can be provided between the membrane 20 and the surface 57 as part of the membrane apparatus.

[0033] Each illustrated portion of the pressurized frame 30 is not a solid block in this embodiment, but rather has a notched recess 35 that extends essentially radially and circumferentially from the radially outer side of the pressurized frame, forming essentially a U-shaped or V-shaped axial cross-section, as shown in Figure 2. In one hypothetical embodiment, the recess 35 between the lower 32 and upper 34 of the pressurized frame 30, connected by the inner portion 33, extends circumferentially over a total of 360°. However, this is only one possible embodiment. In another embodiment, the axial cross-sectional shape shown in Figure 2 can exist as other geometric shapes, or even as a solid block with separable circumferential sections. However, in the above case, it is preferable that these connecting segments do not hinder deformation under axial pressure pushing the upper 34 against the lower 32, in the sense that the compressive load on the thin film 20 does not essentially increase with respect to the load applied through the segment having the recess 35, particularly by the axially extending portion of the lower portion.

[0034] In such intermediate segments, additional local fastening is possible by screws 69 that locally fasten the pressurizing frame components to the main frame 10 in the circumferential direction, having a predetermined height interval that conforms to the membrane 20 and preferably sufficient stress to fix the membrane 20 without further deformation of the membrane 20 (Figure 5). Such additional local fastening can be provided particularly near the intersection of one pressurizing frame component to the next, or additionally at several intermediate positions on one pressurizing frame component 30.

[0035] The number of pressurized frame components is not particularly limited, and it should be understood that three or more are possible, apart from the general possibility of creating a single pressurized frame. In the case of additional fastening by screws, projections 59 can be used to provide internal threads to receive the screws. Alternatively or additionally, such projection pins 59 (without internal threads) can also be used as positioning pins to position corresponding holes in the membrane 20 during the assembly process, and the lower part 32 of the pressurized frame 30 has corresponding axial openings (Figure 3).

[0036] Furthermore, sealing means can be appropriately provided as is generally known to those skilled in the art, such as a (double) annular sealing ring 13 around the manifold 12, an outer sealing ring 14 (Figure 1), or, if necessary, as a seal between the membrane 20 and the side surface of the pressurizing frame 30 facing the main frame 10.

[0037] As can be seen best by comparing Figure 3 and Figure 2, in the relaxed state, the height extension Ha, which is the maximum height extension in the relaxed state, is higher than in the assembled state shown in Figure 2. This is due to the axial pressure during assembly, which positions the electrodes, for example, in the form of bipolar plates 60, relative to the mounting surface 14 of the main frame. The height Ho is set as the axial distance between the sheet surface 57 and the mounting surface 14, which corresponds to the axial height Hp + Hm in the assembled state, where Hp represents the axial extension of the pressurized frame and Hm represents the axial extension of the film.

[0038] It should be noted that, in the assembled state, the frame portion 30 still has enough stress to press the membrane 20 against the main frame, as it cannot withstand the reduction in the common axial extension due to axial pressure. However, in this embodiment, the geometric shape provided by the recess 35 allows the resistance of the membrane to axial compression to be selected to be greater than the resistance of the pressure portion to the reduction in axial extension. In this way, the pressurized frame 30 acts like an elastic, or at least partially elastic, spring against axial compression, and its elastic portion is sufficient to provide the necessary holding force to the membrane 20 without significantly deforming it.

[0039] This allows the membrane 20 to be selected from a wider range of membrane types and structures. With respect to its structure, it is no longer necessary for the membrane to provide the ability to be compressed without the risk of losing its functionality, and a stiffer membrane can be used. On the other hand, the manufacturing of the combination of the main frame 10 and the pressurizing frame device 30 can be carried out with less stringent tolerances, otherwise it is necessary to satisfy the required interrelationship between the compressibility of the Young's modulus of the pressurizing frame in the axial direction so that deformation at the step between the mounting surface 14 and the seat surface 57 remains within an acceptable range while maintaining sufficient stress to sandwich the membrane 20.

[0040] As shown in Figure 4, additional cavities or openings 36, particularly in the form of slits, can be provided near the inner portion 33 of the pressurizing frame 30 to function as release cavities against circumferential pressure, reducing circumferential elongation caused by axial compression due to bending at the intersection between the inner portion 33 and the lower upper portions 32, 34. However, depending on the material and pressure compatibility, these additional openings 36 may be omitted. In the embodiment of Figure 6, it can be recognized that part of the pressurizing frame device may be in the form of a chain having chain elements 30x. The connection can be a hinge connection, for example, by pins, particularly by pins 59 on the sheet surface 57. The membrane can be formed from materials known in the art.

[0041] The pressurized frame component 30 may be formed from a castable and / or injection-molded material, particularly a resin.

[0042] The Young's modulus of the material of the pressurized frame component itself can be greater than that of the membrane, in particular. Nevertheless, due to the geometric shape of the pressurized frame component in the preferred embodiment that gives axial elastic behavior, it is mainly, and particularly effectively, the geometric structure that determines the overall reduction in the axial extension of the pressurized frame 30 and the combination of the pressurized frame 30 and the membrane 20. This allows for improved machining conditions to maintain tolerances while maintaining sufficient stress to maintain proper clamping force of the system in the assembled state, although some axial compression of the membrane may be taken into account, due to greater deformation of the system against normal axial pressure.

[0043] In a preferred method for manufacturing pressurized frame components for a pressurized frame device, the outer shape of the pressurized frame 30 or its components can be formed in a molding step, for example by die casting or injection molding, while other cavities, such as recesses 35 and possibly 36, are formed away from the shape obtained by the molding step through material removal as an arbitrary cutting process, such as mechanical cutting or laser cutting. However, it is also conceivable that the geometric shape of the pressurized frame components be given at least partially or entirely in the molding step, which is preferred to reduce the number of manufacturing steps.

[0044] Furthermore, with respect to the manufacturing process, it is conceivable that the main frame is formed at a first location according to manufacturing parameters including, in particular, the axial distance between the sheet surface 57 and the mounting surface 14, including its tolerances, and that the pressurized frame components of the pressurized frame device are formed at a second location different from the first location according to manufacturing parameters including the axial distance of the film 20, the amount of height extension, and its tolerances, preferably its minimum Young's modulus. However, the second manufacturing location for the pressurized frame components may be the same as that for the main frame.

[0045] In a further preferred embodiment, the forming steps for the outer shape of the pressurizing frame 30 and, optionally, the geometric shape of the pressurizing frame 30 that provides axial elasticity, are formed according to first manufacturing data, independent of the actual data of the film, and only the material removal step is performed according to the parameters of the film. This allows the first forming step to be performed in a unified manner, independent of the final selection of the film, while the more flexible manufacturing step of material removal allows for greater diversity in film selection, and, for example, if problems arise when providing the initially intended film, it can be reconsidered later.

[0046] Here again, shifting the constraint implementation from sensitive manufacturing tolerances related to part dimensions to force-side constraints involving a greater reduction in axial extension makes manufacturing easier and increases the diversity of structural assembly configurations.

[0047] It should be understood that the details of the embodiments described herein should not be considered limiting to the present invention. Rather, the features described above and the subsequent claims may be essential to the present invention, either individually or in combination, in various embodiments.

Claims

1. A structural assembly (100) of a staple-type electrolytic cell having a plurality of cells stacked in the axial direction, wherein the structural assembly is The device comprises a main frame (10) having a mounting surface (14) and a sheet surface (57), a pressurized frame device (30), and a membrane device (20) that abuts the sheet surface and is sandwiched between the main frame and the pressurized frame device in the axial direction, wherein the common axial extension (Hp + Hm) of the assembled membrane device and the pressurized frame device is set by the axial distance (Ho) between the mounting surface and the sheet surface, and is achieved by the axial pressure applied during the assembly process. A structural assembly characterized in that the reduction in the common axial extension is mainly brought about by a reduction in the axial extension of the pressurized frame device.

2. The reduction in the main axial extension is mainly brought about by the geometric shape (32, 33, 34, 35) of the pressurized frame device, as described in claim 1.

3. The structural assembly according to claim 1 or 2, wherein the surface area of ​​the cross-section of the pressurized frame device varies over its axially extending portion.

4. The structural assembly according to any one of claims 1 to 3, wherein the geometric features of the geometric shape include a U-shaped or V-shaped axial cross section (32, 33, 34).

5. The structural assembly according to any one of claims 1 to 4, wherein the pressurizing frame device comprises a plurality of segments in the circumferential direction.

6. The structural assembly according to any one of claims 1 to 5, wherein the axial stress on the membrane device in the assembled state is provided by the elastic restoring force of the pressurizing frame device.

7. The structural assembly according to any one of claims 1 to 6, wherein the pressurized frame device has a release cavity (36) for reducing the amount of circumferential elongation while the amount of axial extension is decreasing.

8. The structural assembly according to any one of claims 1 to 7, wherein the axial deformation of the membrane device is at least locally less than 80% of the deformation of the pressurized frame device.

9. The structural assembly according to any one of claims 1 to 8, wherein the membrane device (20) has positioning holes that match positioning pins (59) on the sheet surface (57).

10. A method for manufacturing a pressurized frame device of a structural assembly according to any one of claims 1 to 9, comprising the steps of providing an external shape for a pressurized frame component and providing a geometric shape that provides elasticity by shape within a molding step and / or an additional material removal step.

11. A staple-type electrolytic cell having a plurality of cells stacked in the axial direction, wherein one or more of these cells have the structural assembly described in any one of claims 1 to 9.

12. A method for manufacturing a structural assembly according to any one of claims 1 to 9, comprising the steps of manufacturing a main frame and manufacturing a pressurized frame device in accordance with the axial distance between the mounting surface and the sheet surface of the main frame, such that the reduction in the common axial extension is mainly brought about by a reduction in the axial extension of the pressurized frame device.

13. A method for assembling a staple-type electrolytic cell according to claim 11, comprising the steps of: preparing a plurality of electrolytic cell cells; assembling the cells between two end plates of the electrolytic cell by applying axial pressure; and thereby reducing the common axial extension of the pressurizing frame device and the membrane, wherein the reduction in the common axial extension is mainly brought about by a reduction in the axial extension of the pressurizing frame device.

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