Sealed electrolysis cell

Abstract

The present invention relates to a sealing structure comprising two elements (2, 3), each having a central portion (4, 5) defining an anode chamber (6) and a cathode chamber (7), respectively, and a circumferential flange portion (8, 9); a sheet-like separator (12) having a peripheral edge (13), the separator (12) being disposed between the two elements (2, 3) and separating the anode and cathode chambers (6, 7); and a sealing structure (14) comprising at least first (15) and second gaskets (16), the sealing structure (14) being disposed between the flange portions (8, 9) and the sheet-like separator (12) having a peripheral edge (13). and a sealing structure (14) disposed in the gap (17) between the chambers (6, 7), wherein the first gasket (15) is an inner gasket positioned in a portion of the gap (17) adjacent to the chambers (6, 7) and the second gasket (16) is an outer gasket positioned in a portion of the gap (17) away from the chambers (6, 7), the gaskets (15, 16) are spaced apart from each other in the gap (17) by a section (I), and a circumferential edge (13) of the separator (12) is located in a radial direction between a midpoint (M1) of the first gasket (15) and a midpoint (M2) of the second gasket (16).

Description

[Technical Field]

[0001] The present invention relates to a sealed electrolysis cell according to the preamble of claim 1. [Background technology]

[0002] Bipolar electrolyzers for large-scale production (i.e., megawatt range) of hydrogen and / or chlorine can be classified into two main design categories: single element designs and filter press designs.

[0003] In single-element electrolysis cells, the electrolysis cell is a separately sealed unit. Each electrolysis cell includes two elements forming a half shell with a pot-shaped central section and a circumferential flange section. The two half shells are bolted together at their flange sections, with a separator, a gasket, and an insulating layer interposed between them. The sealing force for sealing the electrolysis cell is provided by a number of bolts distributed circumferentially along the flange sections of the elements. The separator extends to the outside of the cell through a sealing arrangement and is clamped on both sides by overlapping gaskets. An example of this type of electrolysis cell is known, for example, from DE 102004028761 A1.

[0004] In a filter press electrolyzer, a stack of electrolytic cells is formed in a cell rack by stacking multiple elements with sheet separators and gaskets interposed between adjacent elements and compressing the entire stack to seal all the electrolytic cells at once. In a filter press electrolyzer, each element defines the anode chamber of one electrolytic cell and the cathode chamber of the adjacent electrolytic cell within the stack by means of a bipolar wall. The sealing force for all cells is provided by tie rods extending along the stack. The sealing structure, in which separators extend outside the cells and are clamped on both sides by overlapping gaskets, is similar to that of a single-element design. An example of this type of electrolytic cell is known from JP 2012-193437 A.

[0005] In both types of electrolysis cells, either an ion-exchange membrane or a porous diaphragm is used as the separator, depending on the intended use of the cell. For example, in chloralkali electrolysis, a membrane is used as the separator because the anode and cathode chambers are filled with different types of electrolytes, i.e., brine and caustic, and the membrane prevents mixing of these electrolytes. Instead, a porous diaphragm is preferred, for example, in alkaline water electrolysis. In both cases, a separator extending outside the sealing structure poses a potential risk of electrolyte leakage to the outside of the cell, for example, due to imprecision during assembly. In particular, with porous diaphragms, this risk is increased by the capillary effect of the pores, which allow electrolyte to escape from the inside of the cell due to the narrow spaces caused by the internal structure of the diaphragm. The capillary effect cannot be stopped regardless of the applied force. Rather, it is only a matter of time before the first leaks appear.

[0006] EP 3608445 A1 addresses the above-mentioned shortcomings of conventional sealing structures and provides an alkaline water electrolyzer in which a porous diaphragm is held between an anode chamber frame and a cathode chamber frame via an anode gasket and a cathode gasket, and the anode gasket and the cathode gasket are in contact with each other around the periphery of the porous diaphragm by compressing the anode and cathode gaskets. To secure the porous diaphragm in the cell while simultaneously safely preventing leakage from the cell, EP 3608445 A1 teaches that the contact width between the diaphragm and the gasket and the width of direct contact of the gasket each have a width of at least 3 mm. To simultaneously accomplish these two tasks, the separator must be manufactured and positioned within tight tolerances or a wide gasket must be used, requiring a higher compression force to provide the specified sealing surface pressure. EP 1 477 584 A1 discloses an electrolysis cell seal using a cell sealing cord and a cord-shaped spacer element, the cord-shaped spacer element being spaced from the sealing cord by a multiple of its maximum thickness or diameter. However, only the inner sealing cord has an effective sealing effect. The purpose of the spacer element is to limit the tilting of the two halves of the cell housing when the seal is clamped. JP 10-286572 A describes a sealed electrolysis cell as described in the preamble of claim 1. To reliably prevent leakage of liquid from the cathode chamber, two donut-shaped grooves are formed in the cathode chamber frame, and first and second seals are pressed, deformed, and elastically packed into the grooves. On their respective other sides, the first seal is in contact with the ion exchange membrane, while the second seal is in contact with the inside of the anode chamber frame. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Application Publication No. 102004028761 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-193437 [Patent Document 3] European Patent Application Publication No. 3608445 [Patent Document 4] European Patent Application Publication No. 1477584 [Patent Document 5] Japanese Patent Application Publication No. 10-286572 Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to provide an electrolysis cell that is easy to assemble and has a sealing arrangement that safely prevents leakage from the cell. [Means for solving the problem]

[0009] This object is achieved by an electrolysis cell according to the features of claim 1.

[0010] Provided herein is an electrolysis cell comprising two elements, each of which has a central portion defining an anode chamber and a cathode chamber, respectively, and a circumferential flange portion. The electrolysis cell further comprises an anode housed in the anode chamber, a cathode housed in the cathode chamber, and a sheet-like separator having a peripheral edge. The separator is disposed between the two elements and separates the anode chamber and the cathode chamber. The electrolysis cell further comprises a sealing structure having at least a first gasket and a second gasket, the sealing structure being disposed in the gap between the flange portions of the elements to fasten the separator and seal the anode chamber and the cathode chamber. According to the present invention, the first gasket is an inner gasket positioned in the portion of the gap adjacent to the chamber, and the second gasket is an outer gasket positioned in the portion of the gap away from the chamber. The gaskets are spaced apart from each other by a section in a gap, and the separator is fastened in the cell by the first gasket, with the circumferential edge of the separator positioned radially between the midpoint of the first gasket and the midpoint of the second gasket.

[0011] The section between the gaskets is defined by the outer edge of the inner first gasket and the inner edge of the outer second gasket. A section in the sense of this disclosure should be understood as a closed section, i.e., including its endpoints.

[0012] The sealing structure according to the present invention has the advantage that two functions of the gasket, i.e., fixing the separator inside the electrolysis cell to prevent internal leakage between the chambers and preventing external leakage, are each performed separately by a single gasket. The offset arrangement of the first and second gaskets and the positioning of the separator edge in the space between the midpoints of the two gaskets ensure that the separator does not come into direct contact with the outside of the cell. The gap between the flange portions of the elements is rather completely closed to the outside by at least half the width of the outer gasket. The inner gasket fixes the separator inside the electrolysis cell and prevents leakage, particularly gas leakage, between the anode and cathode chambers.

[0013] The section between the two gaskets has the additional advantageous effect of providing additional manufacturing tolerances for separator cutting and separator positioning during cell assembly. By positioning the separator edge between the midpoints of the two gaskets, the separator tolerance corresponds to the sum of the section and the average width of the two gaskets. This simplifies cell manufacturing.

[0014] Preferably, the separator edge is located within the section between the first gasket and the second gasket. Therefore, the separator edge can be between the outer edge of the first gasket and the inner edge of the second gasket, or can be flush with either of these edges. In these embodiments, the entire width of the first gasket is used to fasten the separator within the cell, and the entire width of the second gasket is used to seal the outer cell, resulting in a particularly secure cell seal. Furthermore, the outer gasket can be used as a form-fitting positioning aid for the separator during cell assembly.

[0015] In a preferred embodiment, the separator is a porous membrane. The sealing structure of the present invention is particularly useful in combination with a porous membrane, since it is particularly difficult to prevent leakage due to the capillary effect with conventional sealing structures. The capillary effect of the porous structure only reaches the edge of the separator, which is safely sealed to the outside by the second gasket, so the capillary effect cannot be avoided with the sealing structure of the present invention.

[0016] Preferably, the sealing arrangement comprises exactly two gaskets. Two gaskets are sufficient to provide one gasket per function, i.e., one gasket per sealing of the inside and outside of the cell. Eliminating the need for any additional gaskets simplifies assembly and reduces material costs.

[0017] The sealing structure further includes an electrically insulating layer disposed within the gap such that a first surface of the insulating layer contacts the first gasket and a second, opposing surface of the insulating layer contacts the second gasket. The insulating layer provides electrical insulation between the elements. By disposing the gaskets on both sides of the insulating layer, each flange portion directly contacts one of the gaskets, achieving particularly good sealing performance.

[0018] The width of the intervals between the gaskets is subject to a trade-off between the ease of manufacture due to the large tolerances at high interval widths and the large space requirements that come with high interval widths. For practical reasons, the intervals are preferably selected in the range of 1 mm to 20 mm, more preferably 2 mm to 10 mm. In particular, it is preferred that the intervals be in the range of 0.5 to 1.5 times the minimum width of the gasket.

[0019] Preferably, the gasket is compressed in the gap by the threaded connection of the flange portion. Specifically, the threaded connection includes at least two beams that compress the flange portion from both sides and bolts that connect the beams, the bolts being positioned outside the second gasket. In this configuration, the bolts are positioned outside both gaskets, so they do not impair the sealing effect of the gaskets. The beams are used to transmit the force applied radially inward by the bolts to the first and second gaskets to provide the necessary sealing surface pressure.

[0020] In a preferred embodiment, the central portion is a pot-shaped half shell and the electrolysis cell is of single element design. In an alternative embodiment, the central portion forms the bipolar wall and the flange portions are provided by a solid frame such that the elements are stacked and configured according to a filter press design.

[0021] The elements are preferably made of metal, particularly preferably nickel and / or titanium.

[0022] In particular, the present invention relates to industrial scale electrolysis cells used in chlor-alkali or alkaline water electrolysis. Thus, the separator of the electrolysis cell according to the present invention is preferably 1 m 2 ~5m 2 Furthermore, the electrolytic cell preferably has an area of ​​at least 3 kA / m 2 It is configured to a current density of .

[0023] 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]

[0024] [Figure 1] 1 shows a schematic, partially exploded cross-sectional view of a first embodiment of an electrolysis cell of the present invention of single element design; [Figure 2] 1 shows a schematic, partially exploded cross-sectional view of a second embodiment of an electrolytic cell of the invention in a filter press design; DETAILED DESCRIPTION OF THE INVENTION

[0025] In the drawings, like parts are identified by the same reference numerals throughout and, therefore, are generally described and referenced only once.

[0026] In Figure 1 a first embodiment of an electrolysis cell 1 according to the invention is shown in a partially exploded state.

[0027] The electrolysis cell 1 comprises two elements 2, 3. Each element 2, 3 includes a central portion 4, 5 and a circumferential flange portion 8, 9 that respectively define an anode chamber 6 and a cathode chamber 7. An anode 10 is housed within the anode chamber 6, and a cathode 11 is housed within the cathode chamber 7.

[0028] Additionally, the anode and cathode chambers 6, 7 contain elements for supporting the electrodes 10, 11 and distributing electrical current, as well as components for distributing electrolyte within the cell 1 and removing spent electrolyte and electrolysis products from the cell 1. These elements are not shown in FIG. 1 for simplicity.

[0029] The electrolysis cell 1 further comprises a sheet-like separator 12 having a peripheral edge 13. The separator 12 is disposed between the two elements 2, 3 and separates the anode and cathode chambers 6, 7. In addition, the electrolysis cell 1 comprises a sealing arrangement 14 having a first gasket 15 and a second gasket 16. The sealing arrangement 14 is disposed in a gap 17 between the flange portions 8, 9 of the elements 2, 3 to fasten the separator 12 and seal the anode chamber 6 and cathode chamber 7.

[0030] The first gasket 15 is an inner gasket positioned in a portion of the gap 17 adjacent to the chambers 6 and 7, and the second gasket 16 is an outer gasket positioned in a portion of the gap 17 away from the chambers 6 and 7. The gaskets 15 and 16 are spaced apart from each other in the gap 17 by a section I. The separator 12 is fastened within the cell 1 by the first gasket 15. The peripheral edge 13 of the separator 12 is located radially between a midpoint M1 of the first gasket 15 and a midpoint M2 of the second gasket 16. The midpoints M1 and M2 are the midpoints of the gaskets 15 and 16 in the width direction, i.e., the radial direction of the cell 1.

[0031] In the embodiment shown in Fig. 1, edge 13 of separator 12 is located within section I between first gasket 15 and second gasket 16. Section I is preferably within the range of 1 mm to 20 mm, more preferably 2 mm to 10 mm.

[0032] The gaskets 15 and 16 may be, for example, frame-shaped rubber sheets. The gaskets 15 and 16 are required to be resistant to, for example, corrosive electrolytes and generated gases, and to be capable of long-term use. Therefore, taking into consideration chemical resistance and hardness, the gaskets 15 and 16 are preferably made of, for example, vulcanized or peroxide-crosslinked ethylene-propylene-diene rubber (EPDM) or ethylene-propylene rubber (EPM). If necessary, at least the area of ​​the gasket that comes into contact with the liquid may be coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

[0033] The separator 12 is preferably a porous diaphragm. Particularly preferably, the porous diaphragm may be a diaphragm for alkaline water electrolysis. Such a diaphragm for alkaline water electrolysis typically includes a sheet-like porous support and an organic polymer resin impregnated into the support. The support may be a nonwoven fabric, a woven fabric, or a composite of a nonwoven fabric and a woven fabric. The support is preferably made of at least one fiber selected from the group consisting of polyphenylene sulfide, polypropylene, polysulfone, polyethersulfone, polyphenylsulfone, fluororesin, polyketone, polyimide, and polyetherimide. The organic polymer resin preferably includes at least one selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polycarbonate, polytetrafluoroethylene, polypropylene, polyphenylene sulfide, polyketone, polyetheretherketone, polyimide, and polyetherimide.

[0034] Alternatively, the separator 12 may be an ion exchange membrane.

[0035] The sealing structure 14 further includes an electrically insulating layer 18 disposed within the gap 17 such that a first surface 19 of the layer 18 contacts the first gasket 15 and a second, opposing surface 20 of the layer 18 contacts the second gasket 16.

[0036] Section I is preferably within a range of 0.5 to 1.5 times the minimum widths W1 and W2 of the gaskets 15 and 16. The minimum widths W1 and W2 are measured when the gaskets are in an uncompressed state. The gaskets 15 and 16 preferably have a width within a range of 4 mm to 10 mm and a height within a range of 1 mm to 4 mm when in an uncompressed state.

[0037] The central portions 4, 5 of elements 2, 3 in FIG. 1 are pot-shaped half shells, and the electrolysis cell 1 is a single-element design. Gaskets 15, 16 are compressed within the gap by threaded connections 21 on flange portions 8, 9. The threaded connections 21 include at least two beams 22, 23 that compress flange portions 8, 9 from either side, and bolts 24 that connect the beams 22, 23 when the bolts 24 are tightened. The bolts 24 are positioned outside the second gasket 16. Washers 25, 26 are preferably provided to transfer and distribute the bolt force to the beams 22, 23.

[0038] In the operating state of cell 1, as compared to the partially disassembled state shown in FIG. 1, bolts 24 are tightened so that gaskets 15, 16 are compressed within gap 17 and separator 12 and insulating layer 18 are clamped between flange portions 8, 9.

[0039] Figure 2 shows a second embodiment of an electrolysis cell 1 according to the invention. The electrolysis cell 1 shown in Figure 2 differs from the first embodiment in that the central portions 4, 5 of the elements 2, 3 form bipolar walls, and the flange portions 8, 9 are provided by a solid frame 27. The elements 2, 3 are therefore configured to be stacked according to a filter press design, in which the sealing force for all electrolysis cells 1 in the stack is provided by tie rods extending along the stack.

[0040] Therefore, in all other respects, the description of the first embodiment shown in FIG. 1 is applicable to the second embodiment shown in FIG. [Explanation of symbols]

[0041] 1 electrolysis cell A few elements 4, 5 central part 6 Anode Chamber 7. Cathode Chamber 8, 9 Circumferential flange part 10 anodes 11 Cathode 12 Separator 13 Separator edge 14 Sealing structure 15 First Gasket 16 Second gasket 17 Gap 18 Insulating layer 19 First surface of insulating layer 20 second surface of insulating layer 21 Threaded connection Frames 22 and 23 24 volts 25, 26 Washers Section I W1 Width of the first gasket W2 Width of second gasket M1 Midpoint of first gasket M2 Midpoint of second gasket

Claims

1. Two elements (2, 3), each of which is a central portion (4, 5) defining an anode chamber (6) and a cathode chamber (7), respectively; and with circumferential flange portions (8, 9), Two elements (2, 3) and an anode (10) housed within said anode chamber (6); a cathode (11) housed within said cathode chamber (7); a sheet-like separator (12) having a peripheral edge (13), said separator (12) being disposed between said two elements (2, 3) and separating said anode and cathode chambers (6, 7); a sealing structure (14) comprising at least a first gasket (15) and a second gasket (16), the sealing structure (14) being disposed in a gap (17) between the flange portions (8, 9) of the elements (2, 3) for fastening the separator (12) and sealing the anode chamber (6) and the cathode chamber (7); Equipped with the first gasket (15) is an inner gasket positioned in a portion of the gap (17) adjacent to the chambers (6, 7), and the second gasket (16) is an outer gasket positioned in a portion of the gap (17) remote from the chambers (6, 7); The gaskets (15, 16) are spaced apart from each other within the gap (17) by a section (I), the separator (12) is fastened within the cell (1) by the first gasket (15), and the circumferential edge (13) of the separator (12) is located between a midpoint (M1) of the first gasket (15) and a midpoint (M2) of the second gasket (16) in the radial direction. In the electrolysis cell, the sealing structure (14) further comprises an electrically insulating layer (18), the electrically insulating layer (18) being disposed in the gap (17) such that a first surface (19) of the layer (18) contacts the first gasket (15) and a second opposite surface (20) of the layer (18) contacts the second gasket (16). Electrolysis cell.

2. 2. The electrolysis cell according to claim 1, characterized in that the edge (13) of the separator (12) is located in the section (I) between the first gasket (15) and the second gasket (16).

3. 2. The electrolytic cell of claim 1, wherein the separator (12) is a porous membrane.

4. 2. The electrolysis cell according to claim 1, characterized in that the number of gaskets provided in the sealing structure (14) is two.

5. 2. The electrolytic cell according to claim 1, wherein the section (I) is in the range of 1 mm to 20 mm.

6. 2. The electrolysis cell according to claim 1, wherein the section (I) is in the range of 0.5 to 1.5 times the minimum width (W1, W2) of the gasket (15, 16).

7. 2. Electrolysis cell according to claim 1, characterized in that the gaskets (15, 16) are compressed in the gaps (17) by means of threaded connections (21) of the flange parts (8, 9).

8. 8. The electrolysis cell according to claim 7, wherein the threaded connection (21) comprises at least two beams (22, 23) compressing the flange portions (8, 9) from both sides and a bolt (24) connecting the beams (22, 23), the bolt (24) being positioned outside the second gasket (16).

9. 9. Electrolysis cell according to any one of claims 1 to 8, characterized in that the central part (4, 5) is a pot-shaped half-shell and the electrolysis cell (1) is of single-element design.

10. 7. Electrolysis cell according to any one of claims 1 to 6, characterized in that the central portions (4, 5) form bipolar walls and the flange portions (8, 9) are provided by a solid frame (27), so that the elements (2, 3) are stacked and arranged according to a filter press design.

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