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 electrolysers 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 electrolytic cells of single-element design, the electrolytic cell is a separately sealed unit. Each electrolytic cell comprises two elements forming a half-shell with a pan-shaped central part and a circumferential flange part. The two half-shells are bolted together at the flange parts of the two half-shells with a separator, a gasket and an insulating layer interposed between them. The sealing force for sealing the electrolytic cell is provided by a number of bolts distributed circumferentially along the flange parts of the elements. The separator extends to the outside of the cell through a sealing arrangement and is clamped from both sides by overlapping gaskets. An example of this type of electrolytic cell is known, for example, from DE 10 2004 028 761 A1.

[0004] In filter press electrolysers, a stack of electrolytic cells is formed in a cell rack by stacking several elements with sheet separators and gaskets interposed between adjacent elements and compressing the whole stack in order to seal all electrolytic cells at once. In filter press design electrolysers, each element defines the anode chamber of one electrolytic cell and the cathode chamber of the adjacent electrolytic cell in the stack by a bipolar wall. The sealing force for all cells is provided by tie rods extending along the stack. The sealing arrangement, in which the separators extend outside the cells and are clamped from both sides by overlapping gaskets, is similar to the single element design. An example of this type of electrolytic cell is known from JP 2012-193437 A1.

[0005] In both types of electrolysis cells, either ion exchange membranes or porous diaphragms are used as separators depending on the intended use of the cell. For example, in chloralkali electrolysis, membranes are used as separators because the anode and cathode chambers are filled with different types of electrolytes, i.e., brine and caustic, which are prevented from mixing by the membrane. Instead, porous diaphragms are preferred, for example, in alkaline water electrolysis. In both cases, separators extending outside the sealing arrangement are a potential risk of electrolyte leakage to the outside of the cell, for example due to imprecision during assembly. Especially in the case of porous diaphragms, the risk is increased by the capillary effect of the pores, caused by the narrow spaces based on the internal structure of the diaphragm, through which the electrolyte can go from the inside of the cell to the outside. 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. In order to secure the porous diaphragm in the cell and simultaneously safely prevent leakage from the cell, EP 3608445 A1 teaches that the contact width between the diaphragm and the gasket and the width of the direct contact of the gasket each have a width of at least 3 mm. To simultaneously fulfill these two tasks, the separator must be manufactured and positioned within tight tolerances or a wide gasket must be used, which requires a higher compression force to provide the specified sealing surface pressure. From EP 1 477 584 A1 an electrolytic cell sealing is known with a cell sealing cord and a cord-shaped spacer element, the latter 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 action. The purpose of the spacer element is to limit the tilting of the two halves of the cell housing to a small extent when clamping the seal. JP 10-286572 A describes a sealed electrolysis cell according to the preamble of claim 1. In order to reliably prevent leakage of liquid from the cathode chamber, two doughnut-shaped recessed grooves are formed in the cathode chamber frame, into which the first and second seals are pressed, deformed and elastically packed. 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] DE 102004028761 A1 [Patent Document 2] JP 2012-193437 A [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 which is easy to assemble and has a sealing arrangement which 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 electrolytic cell comprising two elements, each of which comprises a central portion defining an anode chamber and a cathode chamber, respectively, and a circumferential flange portion. The electrolytic cell further comprises an anode housed in the anode chamber, a cathode housed in the cathode chamber, and a sheet-like separator having a circumferential edge. The separator is disposed between the two elements and separates the anode chamber and the cathode chamber. The electrolytic cell further comprises a sealing arrangement having at least a first gasket and a second gasket, the sealing arrangement 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 invention, the first gasket is an inner gasket positioned in a portion of the gap adjacent to the chamber, and the second gasket is an outer gasket positioned in a portion of the gap away from the chamber. The gaskets are spaced apart from one another by a section in a gap, and the separator is fastened within the cell by a first gasket, the circumferential edge of the separator being radially located between a midpoint of the first gasket and a 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 end points.

[0012] The sealing arrangement according to the invention has the advantage that the two functions of the gasket, namely fixing the separator inside the electrolysis cell to avoid internal leakage between the chambers and preventing leakage to the outside, are each fulfilled separately by one gasket. By the offset arrangement of the first and second gaskets and by positioning the separator edge in the space between the midpoints of the two gaskets, it is achieved that the separator does not directly contact the outside of the cell. The gap between the flange parts 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 in the electrolysis cell and prevents leakage, in particular gas leakage, between the anode and cathode chambers.

[0013] The interval between the two gaskets has the further advantageous effect of providing additional manufacturing tolerances for the separator cutting and for the separator positioning during assembly of the cell. With the separator edge positioned between the midpoints of the two gaskets, the tolerance for the separator corresponds to the sum of the interval and the average width of the two gaskets. Thus, the manufacture of the cell is simplified.

[0014] Preferably, the edge of the separator is located in the section between the first gasket and the second gasket. Thus, the edge of the separator 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 full width of the first gasket is utilized to fasten the separator in the cell, and the full width of the second gasket is utilized to seal the outer cell, resulting in a particularly secure seal of the cell. Furthermore, the outer gasket can be used as a form-fit positioning aid for the separator during assembly of the cell.

[0015] In a preferred embodiment, the separator is a porous membrane. The sealing arrangement 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 arrangements. The capillary effect of the porous structure only reaches the edge of the separator, which is safely sealed against the outside by the second gasket, so the capillary effect cannot be avoided by the sealing arrangement according to the present invention.

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

[0017] The sealing arrangement further comprises an electrically insulating layer disposed within the gap such that a first side of the layer contacts the first gasket and a second opposite side of the layer contacts the second gasket. The insulating layer provides electrical insulation between the elements. By disposing the gaskets on either side of the insulating layer, particularly good sealing performance is achieved since each flange portion is in direct contact with one of the gaskets.

[0018] The width of the intervals between the gaskets is subject to a trade-off between easy 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 are 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 screw connection of the flange portion. In particular, the screw connection comprises at least two beams compressing the flange portion from both sides and bolts connecting the beams, the bolts being positioned outside the second gasket. In such a configuration, the bolts do not impair the sealing effect of the gasket, since they are positioned outside both gaskets. The beams are used to transmit the force applied radially inward by the bolts to the first and second to provide the required 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 a 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 The current density is configured as follows:

[0023] Further advantages of the present invention will be described below with reference to the embodiments illustrated in the accompanying drawings. [Brief description 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 invention of single element design; [Diagram 2] FIG. 2 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 PREFERRED EMBODIMENTS

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

[0026] In FIG. 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 contained within the anode chamber 6 and a cathode 11 is contained 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 the 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 the 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, 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 in the gap 17 by a section I. The separator 12 is fastened in the cell 1 by the first gasket 15. The circumferential edge 13 of the separator 12 is located in the radial direction between a midpoint M1 of the first gasket 15 and a midpoint M2 of the second gasket 16. The midpoints M1, M2 are the midpoints of the gaskets 15, 16 in the width direction, i.e. in the radial direction of the cell 1.

[0031] 1, edge 13 of separator 12 is located within section I between first gasket 15 and second gasket 16. Section I is preferably within a 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 have resistance to, for example, corrosive electrolytes and generated gases, and are also required to be operable for a long period of time. Therefore, 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), taking into consideration chemical resistance and hardness. In addition, at least the area of ​​the gasket to be used that comes into contact with the liquid may be coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), if necessary.

[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-shaped 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, 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, W2 of the gaskets 15, 16. The minimum widths W1, W2 are measured when the gaskets are in an uncompressed state. The gaskets 15, 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 parts 4, 5 of the elements 2, 3 in FIG. 1 are half-shells in the shape of a pan, and the electrolytic cell 1 is of a single-element design. The gaskets 15, 16 are compressed in the gap by a threaded connection 21 of the flange parts 8, 9. The threaded connection 21 comprises at least two beams 22, 23 compressing the flange parts 8, 9 from both sides, and a bolt 24, which connects the beams 22, 23 when the bolt 24 is tightened. The bolt 24 is 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 such 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 parts 4, 5 of the elements 2, 3 form a bipolar wall and the flange parts 8, 9 are provided by a solid frame 27. The elements 2, 3 are therefore arranged to be stacked according to a filter press design, in which the sealing force of all electrolysis cells 1 of 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 Anode 11 Cathode 12 Separator 13 Edge of separator 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 Washer Section I W1 Width of first gasket W2 Width of second gasket M1 Midpoint of the 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), an anode (10) contained within said anode chamber (6); a cathode (11) contained within said cathode chamber (7); a sheet-like separator (12) having a circumferential edge (13), said separator (12) being disposed between said two elements (2, 3) and separating said anode and cathode chambers (6, 7); a sealing arrangement (14) comprising at least a first gasket (15) and a second gasket (16), said sealing arrangement (14) being disposed in a gap (17) between said flange portions (8, 9) of said elements (2, 3) for fastening said separator (12) and sealing said anode chamber (6) and said cathode chamber (7); In an electrolysis cell comprising: the first gasket (15) being an inner gasket positioned in a portion of the gap (17) adjacent to the chambers (6, 7) and the second gasket (16) being 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 in the gap (17) by a section (I), the separator (12) is fastened in the cell (1) by the first gasket (15), and the circumferential edge (13) of the separator (12) is located in the radial direction between a midpoint (M1) of the first gasket (15) and a midpoint (M2) of 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. 3. The electrolytic cell according to claim 1 or 2, characterized in that the separator (12) is a porous membrane.

4. Electrolysis cell according to any one of claims 1 to 3, characterized in that the sealing arrangement (14) comprises exactly two gaskets (15, 16).

5. 5. The electrolysis cell of claim 1, wherein the sealing arrangement (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, opposing surface (20) of the layer (18) contacts the second gasket (16).

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

7. 7. An electrolytic cell according to claim 1, characterized in that the section (I) is in the range of 0.5 to 1.5 times the minimum width (W1, W2) of the gasket (15, 16).

8. 8. Electrolysis cell according to any one of claims 1 to 7, 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).

9. 9. The electrolytic cell according to claim 8, characterized in that the screw connection (21) comprises at least two beams (22, 23) compressing the flange parts (8, 9) from both sides and a bolt (24) connecting the beams (22, 23), the bolt (24) being positioned outside the second gasket (16).

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

11. 8. Electrolysis cell according to any one of claims 1 to 7, characterized in that the central portion (4, 5) forms a bipolar wall and the flange portions (8, 9) are provided by a solid frame (27), such that the elements (2, 3) are arranged in a stack according to a filter press design.

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