Filter press type electrolyzer unit

Abstract

An electrolyzer unit (1) comprising a plurality of electrolytic cells (10) held together along a stacking axis (Oy) between a first intermediate end plate (20) and a second intermediate end plate (30), the first intermediate end plate (20) including first smooth bores (23.1-23.12) and the second intermediate end plate (30) including second smooth bores (33.1-33.12). Tie rods (40.1-40.12). An electrolyzer comprising the electrolyzer unit.

Description

[Technical Field]

[0001] The present invention relates to the field of electrolysers, and more particularly to the field of "filter press" type electrolysers constructed by stacking multiple electrolysis cells, by way of example only, for producing hydrogen. [Background technology]

[0002] Conventionally, electrolyzers include multiple electrolysis cells extending along a stacking axis between two end plates connected to each other by multiple main tie rods. A sealing gasket is disposed between each of the multiple electrolysis cells, and tensioning the main tie rods serves to compress the gasket to seal the fluid flow of electrolyte and gas between the multiple electrolysis cells. Large-capacity electrolyzers can include hundreds of electrolysis cells, making it impractical to assemble them one by one at the location where the electrolyzer is to be used. Therefore, it is known to subdivide an electrolyzer into multiple factory-made electrolysis cell units, each containing multiple electrolysis cells. These electrolysis cell units are then assembled on-site between the two end plates and pressed together using the main tie rods.

[0003] A known electrolytic cell unit includes a first intermediate end plate and a second intermediate end plate, to which multiple electrolytic cells are pressed together using intermediate tie rods. Each intermediate tie rod has a first lug that cooperates with a first notch formed in a first outer surface of the first intermediate end plate and a second lug that cooperates with a second notch formed in a second outer surface of the first intermediate end plate. To install such tie rods in place, the first and second notches must be aligned in line with the lamination axis, requiring strict checking of their alignment. Furthermore, the lugs must be precisely aligned with the notches. Otherwise, interference stresses may appear when the intermediate tie rod is under tension, potentially damaging the intermediate end plates. Removing the intermediate tie rods after the main tie rod is tensioned is also difficult because the lugs of one electrolytic cell unit frequently become jammed by the lugs of an adjacent electrolytic cell unit while the intermediate tie rod is being released. Finally, electrolyzer units are typically shipped with one of their end plates resting on a horizontal surface (i.e., with the stacking axis extending vertically), but are then assembled so that the stacking axis is substantially horizontal, and therefore must be handled very carefully. All of these difficulties slow down the installation of electrolyzers on site, penalizing the overall cost of supplying electrolyzers and thereby slowing the widespread use of such equipment. Summary of the Invention [Problem to be solved by the invention]

[0004] A particular object of the present invention is to improve the cost of supplying an on-site electrolyser. [Means for solving the problem]

[0005] To this end, the present invention provides an electrolytic cell unit comprising a plurality of electrolytic cells held together along a stacking axis between a first intermediate end plate and a second intermediate end plate, the first intermediate end plate including a first smooth bore having a first end opening exiting along an axis substantially perpendicular to the stacking axis, and the second intermediate end plate including a second smooth bore having an end opening exiting along an axis substantially perpendicular to the stacking axis.

[0006] Such units can be easily pressed together without the risk of interference stresses appearing or interfering with adjacent units.

[0007] When the first intermediate end plate includes first electrical connections for the anodes of the plurality of electrolysis cells having first electrical connection ports, and the second intermediate end plate includes second electrical connections for the cathodes of the plurality of electrolysis cells having second electrical connection ports, on-site wiring work is significantly reduced.

[0008] The present invention also provides an intermediate tie rod comprising a body having at a first end a first head with a first smooth shaft projecting along a first axis. At its second end, the body also includes a second head with a second smooth shaft projecting along a second axis, the intermediate tie rod also including first tensioning means for tensioning the intermediate tie rod. Such a tie rod serves to limit the appearance of interference forces while the tie rod is tensioned, facilitating on-site assembly of the electrolyzer unit.

[0009] Such a tie rod is particularly inexpensive when the tensioning means comprises a threaded bushing which engages with the first threaded portion of the first head and the second threaded portion of the body.

[0010] Assembly time may be further reduced when the body includes a first hoist ring and / or when the body includes a cutout configured to receive a hoist cable.

[0011] The intermediate tie rod is easily secured when the first head includes a first bore extending along an axis substantially parallel to the first axis.

[0012] The present invention also provides an electrolysis apparatus comprising at least a first electrolyzer unit and a second electrolyzer unit as described above, held together along a stacking axis between a first end plate and a second end plate, the first end plate and the second end plate being connected to each other by at least one main tie rod.

[0013] Advantageously, the first electrolyzer unit and the second electrolyzer unit are electrically connected in series.

[0014] Alternatively, the first electrolytic cell unit and the second electrolytic cell unit are electrically connected in parallel.

[0015] Other features and advantages of the invention will become apparent on reading the following description of a particular, non-limiting implementation of the invention. [Brief explanation of the drawings]

[0016] Reference is made to the accompanying drawings. [Figure 1] FIG. 1 is a schematic perspective view of an axial cross section of an electrolytic cell unit of the present invention. [Figure 2] FIG. 2 is a schematic perspective view of a first intermediate plate of the electrolytic cell unit of FIG. [Figure 3] FIG. 3 is a schematic perspective view of a second intermediate plate of the electrolytic cell unit of FIG. [Figure 4] 4 is a schematic perspective view of an intermediate tie rod of the electrolytic cell unit of FIG. 1. FIG. [Figure 5] FIG. 5 is a schematic perspective view of a detail of the tie rod of FIG. [Figure 6] FIG. 6 is a schematic diagram of a multiple electrolyzer unit of the present invention. [Figure 7] FIG. 7 is a schematic diagram of the electrolyzer unit in the hoisting situation. [Figure 8]FIG. 8 is a schematic left side view of the electrolytic cell unit of FIG. [Figure 9] FIG. 9 is a right side view of the electrolytic cell unit of FIG. [Figure 10] FIG. 10 is a schematic diagram of an electrolysis apparatus according to the present invention. [Figure 11] FIG. 11 is a schematic diagram of the electrical wiring for the electrolysis device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1 to 5, an electrolytic cell unit of the present invention, generally designated by the reference numeral 1, comprises a plurality of disc-shaped electrolytic cells 10 extending along a stacking axis Oy. Each electrolytic cell 10 is separated from the next by a gasket 11, in this example made of polytetrafluoroethylene. The electrolytic cells 10 are held together between a first intermediate end plate 20 and a second intermediate end plate 30, which are identical and are shown in more detail in FIGS. 2 and 3. The first intermediate end plate 20 is disc-shaped and includes twelve first rectangular blocks 21.1 to 21.12 welded to a periphery 22 (referred to as the "first" periphery) of the first intermediate end plate 20. The first block 21.1 has a first smooth bore 23.1 having a first end 24.1 opening along a first radial axis R21.1 substantially perpendicular to the stacking axis Oy. The first block 21.1 also has two threaded holes 25.1 and 26.1 located on either side of the first smooth hole 23.1.

[0018] Similarly, each of the other first blocks 21.2 to 21.12 has a respective first smooth hole 23.2 to 23.12 having a respective first end 24.2 to 24.12 opening along a respective first radial axis R21.2 to R21.12 substantially perpendicular to the stacking axis Oy, and has two threaded holes 25.2 to 25.12 and 26.2 to 26.12.

[0019] Similarly, the second intermediate end plate 30 is disk-shaped and includes twelve second rectangular blocks 31.1-31.12 welded to a periphery 32 (referred to as the "second" periphery) of the second intermediate end plate 30. The second block 31.1 has a second smooth bore 33.1 having a second end 34.1 opening along a second radial axis R31.1 substantially perpendicular to the stacking axis Oy. Similarly, each of the other second blocks 31.2-31.12 has a respective second smooth bore 33.2-33.12 having a respective second end 34.2-34.12 opening along a respective second radial axis R31.2-R31.12 substantially perpendicular to the stacking axis Oy.

[0020] The electrolyzer unit 1 has a first electrical connection port 28 constituting the anode and a second electrical connection port 38 constituting the cathode. In a conventional manner, the electrolyzer unit 1 includes ducts for distributing the electrolyte and for collecting the various gases produced during electrolysis.

[0021] For handling, transport and assembly of the electrolyser unit 1, the first intermediate end plate 20 and the second intermediate end plate 30 are connected to each other by twelve intermediate tie rods 40.1 to 40.12. As the intermediate tie rods 40.1 to 40.12 are identical, only the first tie rod 40.1 will be described.

[0022] 4 and 5, the first intermediate tie rod 40.1 comprises a body 41.1, in particular in the form of a flattened rolled steel bar, extending along a longitudinal axis O41.1 and comprising a first head 43.1 at its first end 42.1 and a second head 45.1 at its second end 44.1.

[0023] The first head 43.1 has a first threaded section 46.1 to which a third rectangular block 47.1 is welded. A first smooth shaft 48.1, specifically in the form of a right circular cylinder, protrudes from the third block 47.1 along a third axis O48.1 perpendicular to the longitudinal axis O41.1. The first threaded section 46.1 cooperates with a first end 49.1 of a threaded bushing 50.1. A second end 51.1 of the threaded bushing 50.1 cooperates with a second threaded section 52.1 at the first end 42.1 of the body 41.1. The threaded bushing 50.1 has two radial bores 53.1 suitable for receiving clamping pins (not shown). The first threaded section 46.1 and the second threaded section 52.1 are threaded in opposite directions.

[0024] As can be seen in Figure 5, the third block 47.1 has first and second bores 54.1 and 55.1 extending along an axis parallel to the third axis O48.1.

[0025] The second head 45.1 is identical to the third block 47.1 and comprises a fourth rectangular block 56.1 welded to the body 41.1. The second smooth shaft 57.1 is specifically formed as a right cylinder and projects from the fourth block 56.1 along a third axis O57.1 perpendicular to the longitudinal axis O41.1 in a first direction S57.1. The fourth block 56.1 has third and fourth bores 58.1 and 59.1 extending along axes parallel to the third axis O57.1.

[0026] As seen in FIG. 4 , first and second plates 60.1 and 61.1 are welded onto body 41.1 so as to be parallel to third axis O57.1 but protrude from body 41.1 along a second direction S62.1 opposite first direction S57.1. A first distal end 63.1 of first plate 60.1 and a second distal end 64.1 of second plate 61.1 include first and second cutouts 65.1 and 66.1, respectively, which are made by flame cutting in this example. First plate 60.1 also includes a first hoist ring 67.1, which is also made by flame cutting.

[0027] The assembly of the electrolytic cell unit 1 and the intermediate tie rods 40.1 to 40.12 will now be described.

[0028] 1, 100 electrolysis cells 10 and 101 gaskets 11 are arranged alternately on the second intermediate end plate 30. Ducts for distributing the electrolyte and collecting the gases are put into place before the assembly thus constructed is covered by the first intermediate end plate 20.

[0029] The length of the first intermediate tie rod 40.1 is adjusted by means of the bushing 50.1 so that the first smooth shaft 48.1 and the second smooth shaft 57.1 are spaced apart by a distance substantially equal to the distance between the first smooth hole 23.1 in the first intermediate end plate 20 and the second smooth hole 33.1 in the second intermediate end plate 30. The first tie rod 40.1 is then presented so that the first smooth shaft 48.1 and the second smooth shaft 57.1 engage the first smooth hole 23.1 in the first intermediate end plate 20 and the second smooth hole 33.1 in the second intermediate end plate 30, respectively, so that at least a portion of each of the smooth shafts 48.1 and 57.1 abuts the smooth holes 23.1 and 33.1, respectively. The screws are slid in the first bore 54.1, the second bore 55.1, the third bore 58.1 and the fourth bore 59.1.

[0030] The same applies to the intermediate tie rods 40.2 to 40.12.

[0031] The first intermediate tie rod 40.1 is partially tensioned using a pin passed through one of the bores 53.1 in the threaded bushing 50.1. Using conventional tension equalization methods, the other intermediate tie rods 40.2-40.12 are partially tensioned in the same manner.

[0032] Steam is injected into the electrolysis cell through the electrolyte distribution ducts, which applies additional tension to the tie rods 40.1 to 40.12, which causes creep of the gasket 11. This operation is repeated several times until sufficient creep of the gasket 11 is achieved.

[0033] This produces a first electrolyzer unit 1 comprising 100 electrolytic cells 10 pressed between the first intermediate end plate 20 and the second intermediate end plate 30 and held under pressure by the intermediate tie rods 40.1 to 40.12.

[0034] For the sake of clarity, in the following, elements that are identical or similar to those described above will be given the same reference numerals as those used above, but increased by 100 or 200.

[0035] The second electrolytic cell unit 101 is fabricated in a similar manner to fabricating the first electrolytic cell unit 1 by using 100 electrolytic cells 110 pressed between a third intermediate end plate 120 and a fourth intermediate end plate 130 and held under pressure by intermediate tie rods 140.1 to 140.12.

[0036] The third electrolytic cell unit 201 is fabricated similarly to the fabrication of the first electrolytic cell unit 1 by using 100 electrolytic cells 210 pressed between a fifth intermediate end plate 220 and a sixth intermediate end plate 230 and held under pressure by intermediate tie rods 240.1 to 240.12.

[0037] The first electrolyzer unit 1 is handled by means of a lifting bridge having a spreader with six legs, each of which is provided with a sling with a hoist hook attached at its free end. Six hoist rings 67.1, 67.3, 67.5, 67.7, 67.9, 67.11 are secured to the first electrolyzer unit 1, respectively, allowing it to be lifted so that it can be placed on a transport vehicle such as a semi-trailer. The second electrolyzer unit 101 and the third electrolyzer unit 201 are handled in a similar manner.

[0038] During installation on site, the first electrolyzer unit 1 is tilted to a so-called "horizontal" position so that the stacking axis Oy is substantially horizontal (FIG. 7). This can be done in a variety of ways known to those skilled in the art. When in the horizontal position, the electrolyzer unit 1 is handled by a first sling 70 engaged in first notches 65.3-65.111 (FIG. 8), and both ends of the sling are connected to first hooks 71 of a spreader 72 connected to an overhead traveling crane 73.

[0039] A second sling 74 is engaged in the second notches 66.3 to 66.11 (FIG. 9) and the two ends of the sling are connected to second hooks 75 of the spreader 72.

[0040] Referring to Figure 10, the first electrolyzer unit 1, the second electrolyzer unit 101 and the third electrolyzer unit 201 are installed side by side between a first end plate 80 and a second end plate 81. Elastomer gaskets 68 are arranged at the interfaces between the main plates and the intermediate plates and between the intermediate plates of the electrolyzer units 1, 101 and 201. The gaskets 68 provide electrical insulation between the electrolyzer units 1, 101 and 201. For this purpose, four main tie rods 82.1 and 82.4 are placed in holes provided in the first end plate 80 and the second end plate 81, and the tie rods are tensioned.

[0041] The intermediate tie rods 40.1 to 40.12, 140.1 to 140.12, 240.1 to 240.12 are then removed. For example, the intermediate tie rod 40.1 is removed by acting on the threaded bushing 50.1 to release the surface tension of the intermediate tie rod 40.1. The intermediate tie rod 40.1 is removed by translating it along an axis perpendicular to the stacking axis Oy.

[0042] Thereafter, the electrolyzer units 1, 101, 201 are electrically connected. Figure 11 shows a particularly advantageous way of interconnecting the electrolyzer units 1, 101 and 201.

[0043] The first, third, and fifth intermediate end plates 20, 120, and 220 are connected to the first point 90.1, the second point 90.2, and the third point 90.3 of the power supply circuit 90 by means of a first switch 83, a second switch 183, and a third switch 283, respectively. The second, fourth, and sixth intermediate end plates 30, 130, and 230 are electrically connected to the fourth point 90.4, the fifth point 90.5, and the sixth point 90.6 of the power supply circuit 90, respectively. A fourth switch 84 interconnects the first point 90.1 and the fourth point 90.4. A fifth switch 184 interconnects the second point 90.2 and the fifth point 90.5. A sixth switch 284 connects the third point 90.3 and the sixth point 90.6. This configuration allows one or more electrolyzer units to be idle and connected in series or parallel without resorting to extensive cabling, which is costly in terms of both raw materials and installation time.

[0044] When the first electrolyzer unit 1 , the second electrolyzer unit 101 and the third electrolyzer unit 201 are wired together, they form an electrolyzer 1000 .

[0045] If any of the electrolytic cells 10, 110, or 210 fails, the electrolyzer 1000 is emptied and the intermediate tie rods 40.1-40.12, 140.1-140.12, and 240.1-240.12 are placed in place and tensioned. The main tie rods 82.1-82.4 are then loosened and only the electrolyzer unit containing the failed electrolytic cell is removed. A new electrolyzer unit can be quickly installed and connected to the other electrolyzer units, allowing the electrolyzer 1000 to be quickly restarted.

[0046] Naturally, the invention is not limited to the described embodiments, but encompasses any variant that falls within the technical field of the invention as defined by the claims.

[0047] In particular, as described above, the electrolyzer unit has 12 tie rods, however the invention applies equally to electrolyzer units having other numbers of tie rods, for example 2, 3, 4 to 11, or more than 12.

[0048] As noted above, although the intermediate tie rod has a threaded bushing, the invention applies equally to other means for tensioning the tie rod, such as a lever, ratchet wheel, or pneumatic or hydraulic actuator.

[0049] As mentioned above, the hoist rings and notches are made in a plate attached to a flat surface of the body of the intermediate tie rod, but the invention applies equally to hoist rings and / or notches made directly in the body of the tie rod.

[0050] As mentioned above, the smooth shaft is in the shape of a right circular cylinder, however the invention applies equally to smooth shafts of other shapes, for example smooth shafts of square or elliptical cross section, the shaft preferably being cylindrical in shape.

[0051] Notably, all electrolyzer units have 100 electrolytic cells, although the invention applies equally to electrolyzer units having some other number of cells, for example 50 or more than 100 cells, and each of the electrolyzer units may have a different number of electrolytic cells.

[0052] The number of notches through which the sling cable passes depends on the type of sling and the distance between the hook and the electrolyzer unit being handled.

[0053] As described above, the electrolyzer has four main tie rods, however the invention applies equally to electrolyzers having other numbers of main tie rods, for example one, two, three or more than four. The present invention has the following aspects (configurations): [Aspect 1] An electrolyzer unit (1, 101, 201) comprising a plurality of electrolysis cells (10, 110, 210) held together along a stacking axis (Oy) between a first intermediate end plate (20, 120, 220) and a second intermediate end plate (30, 130, 230), the first intermediate end plate (20, 120, 220) includes first smooth holes (23.1-23.12) having first ends (24.1-24.12) opening along an axis substantially perpendicular to the stacking axis (Oy); The second intermediate end plate (30, 130, 230) includes second smooth bores (33.1-33.12) having second ends (34.1-34.12) opening along an axis substantially perpendicular to the stacking axis (Oy), forming an electrolytic cell unit (1, 101, 201). [Aspect 2] the first intermediate end plate (20, 120, 220) includes a first electrical connection (27) for the anodes (12) of the plurality of electrolysis cells (10, 110, 210) having first electrical connection ports (28); the second intermediate end plate (30, 130, 230) includes second electrical connections (37) for the cathodes (13) of the plurality of electrolysis cells (10, 110, 210) having second electrical connection ports (38); 2. The electrolytic cell unit (10, 110, 210) according to embodiment 1. [Aspect 3] An intermediate tie rod (40.1), a body (41.1) provided at a first end (42.1) with a first head (43.1) from which a first smooth shaft (48.1) projects along a first axis (048.1); the body (41.1) provided at a second end (44.1) with a second head (45.1) from which a second smooth shaft (57.1) projects along a second axis (057.1); the intermediate tie rod (40.1) is provided with first tensioning means (50.1) for tensioning the intermediate tie rod (40.1); Intermediate tie rod (40.1). [Aspect 4] The intermediate tie rod (40.1) of aspect 3, wherein the first tensioning means (50.1) includes a threaded bushing (50.1) that engages with the first threaded portion (46.1) of the first head (43.1) and the second threaded portion (52.1) of the body (41.1). [Aspect 5] 5. The intermediate tie rod (40.1) according to any one of aspects 3 to 4, wherein the body (41.1) includes a first hoist ring (67.1). [Aspect 6] The intermediate tie rod (40.1) according to any one of aspects 3 to 5, wherein the body (41.1) includes a notch (63.1, 66.1) arranged to receive a hoist cable. [Aspect 7] The intermediate tie rod (40.1) according to any one of aspects 3 to 6, wherein the first head (43.1) comprises first bores (54.1, 55.1) extending along an axis substantially parallel to the first axis (048.1). [Aspect 8] An electrolysis apparatus (1000) comprising an electrolytic cell unit according to any one of the first to second aspects, the electrolytic cell unit comprising at least a first electrolytic cell unit (10) and a second electrolytic cell unit (110, 210), The electrolyzer (1000) comprises electrolyzer units held together along a stacking axis (Oy) between a first end plate (80) and a second end plate (81), the first end plate (80) and the second end plate (81) being connected to each other by at least one main tie rod (82.1-82.4). [Aspect 9] 9. The electrolysis apparatus (1000) according to embodiment 8, wherein the first electrolytic cell unit (10) and the second electrolytic cell unit (110, 210) are electrically connected in series. [Aspect 10] 9. The electrolysis apparatus (1000) according to embodiment 8, wherein the first electrolytic cell unit (10) and the second electrolytic cell unit (110, 210) are electrically connected in parallel.

Claims

1. An electrolyzer unit (1, 101, 201) comprising at least two electrolyzer units, a plurality of electrolysis cells (10, 110, 210) held together along a stacking axis (Oy) between a first intermediate end plate (20, 120, 220) and a second intermediate end plate (30, 130, 230) connected together by a plurality of intermediate tie rods (40.1-40.12); the first intermediate end plate (20, 120, 220) includes a first smooth hole (23.1-23.12) having a first end (24.1-24.12) opening along an axis substantially perpendicular to the stacking axis (Oy); the second intermediate end plate (30, 130, 230) includes second smooth holes (33.1-33.12) having second ends (34.1-34.12) opening along an axis substantially perpendicular to the stacking axis (Oy); Each intermediate tie rod (40.1-40.12) comprises a body (41.1) provided at a first end (42.1) with a first head (43.1) from which a first smooth shaft (48.1) projects along a first axis (048.1), and the body (41.1) comprises at a second end (44.1) with a second head (45.1) from which a second smooth shaft (57.1) projects along a second axis (057.1); The intermediate tie rods (40.1 to 40.12) are provided with first tensioning means (50.1) which tension the intermediate tie rods (40.1 to 40.12) by the action of the first tensioning means (50.1) before the first smooth shafts (48.1) and the second smooth shafts (57.1) of the intermediate tie rods (40.1 to 40.12) are received in the first smooth holes (23.1 to 23.12) and the second smooth holes (33.1 to 33.12), respectively. and arranged to tension the intermediate tie rods (40.1-40.12) by the action of the first tensioning means (50.1) as soon as the first smooth shaft (48.1) and the second smooth shaft (57.1) of the intermediate tie rods (40.1-40.12) engage with the first smooth holes (23.1-23.12) and the second smooth holes (33.1-33.12), respectively. Electrolyzer unit (1, 101, 201).

2. the first intermediate end plate (20, 120, 220) includes first electrical connections (27) for the anodes (12) of the plurality of electrolysis cells (10, 110, 210) having first electrical connection ports (28); the second intermediate end plate (30, 130, 230) includes second electrical connections (37) for the cathodes (13) of the plurality of electrolysis cells (10, 110, 210) having second electrical connection ports (38); Electrolyzer unit (1, 101, 201) according to claim 1.

3. 2. The electrolytic cell unit (1, 101, 201) according to claim 1, wherein the first tensioning means (50.1) comprises a threaded bushing (50.1) engaging with a first threaded portion (46.1) of the first head (43.1) and a second threaded portion (52.1) of the body (41.1).

4. 2. The electrolyzer unit (1, 101, 201) of claim 1, wherein the body (41.1) includes a first hoist ring (67.1).

5. 2. The electrolyzer unit (1, 101, 201) according to claim 1, wherein the body (41.1) comprises a cutout (63.1, 66.1) arranged to receive a hoist cable.

6. 2. The electrolytic cell unit (1, 101, 201) of claim 1, wherein the first head (43.1) comprises a first bore (54.1, 55.1) extending along an axis substantially parallel to the first axis (048.1).

7. An electrolysis device (1000) comprising an electrolyzer unit (1, 101, 201) according to any one of claims 1 to 6, comprising at least a first electrolyzer unit (1) and a second electrolyzer unit (101, 201), The electrolyzer (1000) comprises electrolyzer units (1, 101, 201) held together along a stacking axis (Oy) between a first end plate (80) and a second end plate (81), the first end plate (80) and the second end plate (81) being connected to each other by at least one main tie rod (82.1-82.4).

8. 8. The electrolysis apparatus (1000) of claim 7, wherein the first electrolyzer unit (1) and the second electrolyzer unit (101, 201) are electrically connected in series.

9. 8. The electrolysis apparatus (1000) of claim 7, wherein the first electrolyzer unit (1) and the second electrolyzer unit (101, 201) are electrically connected in parallel.

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