Method for joining a stack of elements together

Abstract

The invention relates to a method for joining a stack of elements together, the method comprising the steps of: individually joining subassemblies of the elements together; joining the subassemblies together by arranging a joint between each subassembly to form the stack of elements; applying consecutive phases of heating and cooling to the stack of elements while applying at least one clamping action to the stack of elements between two different phases of heating and cooling.

Description

[0001] METHOD FOR ASSEMBLING A STACK OF ELEMENTS TOGETHER

[0002] The invention relates to a method of assembling a stack of elements together.

[0003] The invention preferably relates, but in a non-limiting manner, to a method of assembling an electrolyzer cell.

[0004] BACKGROUND OF THE INVENTION

[0005] The overall architecture of an electrolyzer stack (generally referred to as an "electrolyzer stack") usually consists of a block of electrolytic cells, which are stacked in series from an electrical point of view and in parallel from a fluidic point of view, and seals.

[0006] Each electrolytic cell aims to promote 1 1electrolysis of an electrolytic solution (alkaline water, pure water, unpurified water, salt, aqueous chloride solution, aqueous bromide solution, aqueous hydrochloric acid solution, etc.). For example, the functionality of an electrolyzer cell is to promote the reaction of production of hydrogen (H2) and oxygen (02) gas resulting from the dissociation of water after injecting a direct electric current into an alkaline solution, generally potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0007] Each electrolytic cell, considered as a mainly metallic and conductive part (but some parts of which may be non-metallic), is generally composed of two bipolar plates, framing two interlayers (better known under the English term "flow field material"), themselves framing two electrodes generally in the form of plates or grids or metallic fabrics. In the case of an alkaline electrolyzer cell, said electrodes are generally made of nickel. The two electrodes (a cathode and an anode) are separated by a membrane (also called a diaphragm or porous separator in the case of the alkaline electrolyzer), which ensures electrical insulation between the two electrodes, the separation of gases as well as ionic conduction within the electrolytic cell.

[0008] The interlayer has two functions: i) to provide a low resistivity metallic path between each bipolar plate and the associated electrode and ii) to allow proper circulation of the electrolytic solution for cooling the electrolyzer stack and transporting the generated gases.

[0009] The name bipolar plate comes from the fact that as the electrolytic cells are all attached to each other, an N bipolar plate will have a potential: higher compared to the N+l bipolar plate downstream, so that the N bipolar plate will play the role of anode within an electrolytic cell defined by the N and N+l bipolar plates; lower compared to the Nl bipolar plate upstream, so that the N bipolar plate will play the role of cathode within an electrolytic cell defined by the Nl and N bipolar plates.

[0010] Among the other metal parts, in addition to the bipolar plates, are listed the distribution plates (which allow the power supply and electrical distribution of the electrolytic cells) as well as the base plates (allowing the demarcation of all the electrolytic cells and ensuring the clamping of said cells between them and their sealing).

[0011] Indeed, the electrolyzer stack ends with two bottom plates located just before the first electrolytic cell and just after the last stacked electrolytic cell, in other words one bottom plate is located upstream of the block of electrolytic cells and the other bottom plate is placed downstream of the latter in order to physically delimit the two ends of said block of electrolytic cells.

[0012] The electrolytic solution present in each electrolytic cell as well as the gases produced by 1 1electrolysis (such as hydrogen gas, oxygen gas, chlorine gas and halogen gas ...) must not leak from the edge of the diaphragm to the outside of the electrolytic cell in question but must circulate only through the dedicated pipes (each pipe being dedicated either to the electrolyte alone, or to the electrolyte mixed with one of the gases, taking into account that the two gases cannot also mix with each other).

[0013] The electrolyser cell cannot therefore operate continuously if a leak is detected, said leak coming either from the electrolytic solution, or from the gases generated by the electrolysis, or from any other substance.

[0014] In many cases, various problems arise with a negative impact on the environment and also on the safety of operators, presenting a variable degree of severity, although the latter can reach a significantly high value linked to irreversible consequences.Conventionally, in an electrolytic cell such as that described above, the assembly followed in order to avoid any leakage from the electrolytic solution, the gas(es) generated by the electrolysis and / or any other substance, from the edge of the diaphragm of the electrolytic cell to the outside of said electrolytic cell, is based on the use of several thin plate-shaped seals or several toric rings ("O-rings" in English), and often made of elastomer, so that said seals or rings are arranged between the anode and the cathode or the membrane of an electrolytic cell, or directly between two adjacent bipolar plates. Thus, the diaphragm is sandwiched between these different sealing elements.

[0015] Although these seals have good sealing properties, they can be penalized by the creep phenomenon, which also has a more or less significant intensity depending on the quality and composition of the material used. Thus, if such seals are used, the sealing of the electrolyzer stack ends up being deteriorated in general (and even more specifically within each electrolytic cell). In addition, this creep phenomenon occurs all the more quickly if one of the influencing factors, such as temperature, causes unwanted effects on the seal in question.

[0016] SUBJECT OF THE INVENTION

[0017] One aim of the invention is to propose a solution for ensuring good sealing in an assembly of a stack of elements between them and this over the long term.

[0018] SUMMARY OF THE INVENTION

[0019] To this end, the invention provides a method for assembling a stack of elements, comprising the steps of:

[0020] Individually assemble subsets of said elements,

[0021] Assemble the subassemblies together by arranging a joint between each subassembly to form the stack of elements, Apply successive heating and cooling phases to the stack of elements by applying at least one tightening of the stack of elements between two different heating and cooling phases.

[0022] The inventors were able to observe, surprisingly, that applying successive tightenings, at different temperatures, constituted a means of controlling the creep of the joints by causing it prematurely but deliberately in order to eliminate it as much as possible before the actual commissioning of the stack of elements.

[0023] In particular, the invention makes it possible to achieve high mechanical stability at the level of the joint material by alternating thermal (heating and cooling of the elements) and mechanical (compression of the elements) stresses.

[0024] The invention thus makes it possible to ensure good final sealing of the stack of elements, even over the long term, for example over a time scale of 10 to 20 years.

[0025] The invention proves to be particularly suitable for the assembly of stacks of large elements.

[0026] Optionally, the cell stack is an electrolyzer stack, the subassemblies thus being pairs of electrolytic half-cells.

[0027] The process thus ensures good final sealing of the electrolyser stack, even in the long term, for example over a time scale of 10 to 20 years.

[0028] The method proves to be particularly suitable for use in a large electrolyser stack in which the bipolar plates can reach several square metres of electrode surface area per electrolytic cell and / or in an electrolyser stack intended to work at high pressure (for example at a pressure at a value between 1 and 3 Megapascals and for example at a pressure at a value between 3 and 5 Megapascals and for example at a pressure greater than 5 Megapascals).

[0029] Optionally, the cell stack is an electrolyzer stack, the subassemblies thus being pairs of electrolytic half-cells.

[0030] Optionally, the method comprises a step of pre-tightening the stack of elements before the step of applying successive heating and cooling phases to the stack of elements by applying at least one tightening of the stack of elements between two different heating and cooling phases.

[0031] Optionally, the pre-tightening step is carried out in stages.

[0032] Optionally, the elements are heated by injecting steam into the elements.

[0033] Optionally the steam is water vapor.

[0034] Optionally, the elements are heated by injecting hot water into the elements.

[0035] Optionally, the cooling of the elements is forced.

[0036] Optionally, the cooling of the elements is natural.

[0037] Optionally, at least two iterations of the following phases are carried out:

[0038] Heating the interior of the stack of elements, Clamping the different elements together, Cooling the different elements together, Clamping the different elements together.

[0039] Optionally, the iterations are stopped when at least a predefined compression rate of at least one joint of the element stack is reached.

[0040] Optionally at least one subassembly is assembled by fixing two bipolar plates together so as to tighten at least one joint between the two plates. Optionally a single joint is tightened between the two bipolar plates.

[0041] Optionally the element stack is arranged vertically and / or horizontally.

[0042] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Reference will be made to the attached drawings, including:

[0045] [Fig. 1] Figure 1 is an exploded schematic view of an electrolytic cell of an electrolyzer stack assembled according to a particular embodiment of the invention,

[0046] [Fig. 2] Figure 2 is a perspective view of a bipolar plate of the electrolytic cell shown in Figure 1,

[0047] [Fig. 3a] Figure 3a is a sectional view of a portion of the bipolar plate shown in Figure 2,

[0048] [Fig. 3b] Figure 3b is a sectional view of a portion of the bipolar plate illustrated in Figure 2, a membrane of said electrolytic cell also being present,

[0049] [Fig. 3c] Figure 3c is a sectional view of a portion of the electrolytic cell shown in Figure 1, [Fig. 4] Figure 4 is a view of an electrolyzer stack comprising electrolytic cells as shown in Figure 1,

[0050] [Fig. 5] Figure 5 is a graph illustrating the average thickness reduction of a joint of one of the cells of the electrolyzer stack illustrated in Figure 4 during assembly of said stack.

[0051] DETAILED DESCRIPTION OF THE INVENTION

[0052] With reference to the various figures, a stack of elements extends longitudinally in a general direction A. In the present case, the stack of elements is an electrolyser stack, the various elements being mainly formed by electrolytic cells which will be described below.

[0053] The pile of 1electrolyzer 1 comprises a block 2 of electrolytic cells which comprises at least two electrolytic cells which are mounted adjacent to each other in the general direction A. Within the block 2, the electrolytic cells are mounted in parallel from a fluidic point of view and in series from an electrical point of view.

[0054] At both ends (along the general direction A) of block 2, the electrolyser stack 1 has two bottom plates 3 and 4.

[0055] These bottom plates 3 and 4 form supports between which the electrolytic cells are compressed so that the electrolyser stack 1 is sealed and so that a good quality electrical contact is created inside the electrolytic cells.

[0056] In addition, the base plates 3 and 4 can support the forces generated by the internal pressure in block 2 as well as the external forces in block 2 necessary to ensure the compression of block 2.

[0057] Bottom plates 3 and 4 can act as electrical conductors and current distributors.

[0058] Preferably, the electrolyser cell 1 comprises a first distribution plate 5 associated with the first bottom plate 3 and a second distribution plate 6 associated with the second bottom plate 4. It is then the distribution plates 5 and 6 which will here play the role of electrical conductor and current distributor.

[0059] The first distribution plate 5 (associated with the positive terminal) is arranged upstream of the block 2 and the second distribution plate 6 (associated with the negative terminal) is arranged downstream of said block 2.

[0060] The concepts "upstream" and "downstream" are understood according to the direction of flow of the current through block 2.

[0061] A first of the two distribution plates 5 is connected to the positive terminal of the electrolyser cell 1. Then, a portion of the main internal face of the first bottom plate 3 (main face facing the block 2 and in particular the distribution plate 5) is covered with a pellet made of electrically insulating material. Said portion is for example arranged in the centre of said main internal face.

[0062] The second of the two distribution plates 6 is connected to the negative terminal of the electrolyser cell 1. The second bottom plate 4 will be at the same potential and also serves as a gateway for the supply of an electrolytic solution and the exhaust of this same solution charged with the gases formed during electrolysis in the block 2.

[0063] Thus, holes are provided in said second bottom plate 4. Said holes often have a different section between the two main faces of the second bottom plate 4. For example, the external main face (the one facing the outside of the block 2) has one or two holes (for example cylindrical in shape) for supplying electrolytic solution and two holes for discharging electrolytic reaction products in addition to the heated electrolytic solution. Three or four holes are drilled on the internal main face (opposite the external main face) of said second bottom plate 4 for the same purpose, and for example oblong holes to improve the distribution or collection of fluids. For example, the holes in the external main face are equipped with suitable flanges for connecting the inlet and return pipes for the electrolytic solution.

[0064] Furthermore, the electrolyser cell 1 is supplied with direct current here.

[0065] For example, the first distribution plate 5 has a potential of approximately 700 Volts, while the second distribution plate 6 has a potential of 0 Volts. The supply and removal of electrolytic solution takes place at the level of the second distribution plate 6 and the second base plate 4, the distribution plate 6 having a potential of 0 Volts, which prevents any current leakage (the potential of the second distribution plate 6 being that of the earth).

[0066] Inside the electrolyser stack 1, the current passes through the electrolytic solution through a membrane 11 which will be introduced below. Within the block 2 there are seals (which will be described below): these seals are chosen from a material having a much greater electrical resistance than that of the electrolytic solution.

[0067] The electrolyser stack 1 comprises an end seal (not visible in the figures) arranged between the first distribution plate 5 and the first bottom plate 3. However, the first bottom plate 3 is grounded so that the potential difference at said end seal reaches the same value as the voltage applied between the positive and negative terminals of the electrolyser stack 1, for example, substantially 700 Volts.

[0068] As a result, the first bottom plate 3 is electrically insulated from the block 2. For example, the electrolyzer stack 1 comprises a layer (not visible in the figures) of electrically insulating material, a layer arranged between the first bottom plate 3 and the first distribution plate 5.

[0069] The layer is for example an added disc or a deposit made on the first base plate 3 and / or the first distribution plate 5.

[0070] The electrolyzer stack 1 comprises means for fixing the different electrolytic cells 10 together by common clamping.

[0071] For example, the fixing means comprise a plurality of tie rods 7. Each tie rod 7 extends rectilinearly in the electrolyzer stack 1. Each tie rod 7 thus extends longitudinally in the electrolyzer stack 1 parallel to the general direction A. Each tie rod 7 is shaped into a rod.

[0072] The tie rods 7 therefore all extend parallel to each other.

[0073] The tie rods 7 are positioned around the perimeter of the various electrolytic cells. Preferably, the tie rods 7 are distributed all around the block 2 and preferably at a regular interval.

[0074] The tie rods 7 extend through the bottom plates 3 and 4 of the electrolyser stack 1, through specific holes in said bottom plates 3 and 4, and thus each have two ends external to the block 2.

[0075] Preferably, the tie rods 7 are partially covered with a sleeve made of electrically insulating material. This prevents short circuits between the electrolytic cells in the event of contact or projection. For example, the sleeve extends over the entire section of the tie rod 7 arranged between the two base plates 3 and 4.

[0076] Preferably, the ends of the tie rods 7 are threaded. For example, the threads at the ends are rolled threads. The rolled threads will have the advantage of making the machining of the tie rods 7 easier, particularly if the tie rods 7 are of a significant length, for example several meters in length.

[0077] The fixing means also comprise nuts 8 screwed onto the ends of the tie rods 7.

[0078] The nuts 8 make it possible to constrain the two bottom plates 3 and 4 together, and therefore the different electrolytic cells together, which ensures good sealing of the stack of electrolytic cells. Preferably, the fixing means also comprise means for prestressing the two bottom plates 3 and 4 together and therefore the different electrolytic cells together. Said prestressing means also make it possible to absorb deformations and / or variations in thickness of the elements constituting the electrolyser stack 1, due to thermal expansion or variations in mechanical stresses external and internal to the electrolyser stack 1 (such as for example the internal pressure in the electrolyser stack).

[0079] The prestressing means are received on the ends of the tie rods 7 so as to be arranged, for a given end, between the nearest base plate (3 or 4) and the nuts 8 arranged on the same end.

[0080] For example, the fixing means comprise spring washers 9 such as Belleville washers. The spring washers 9 are received on the ends of the tie rods 7.

[0081] The spring washers 9 are more precisely arranged here on each tie rod 7, at the level of the external part of said tie rod 7, when the latter has passed through the nearest bottom plate (3 or 4). The fixing means thus described allow the electrolyser stack 1 to cope in particular with thermal expansions and / or variations in mechanical stresses external and internal to the electrolyser stack 1 (such as for example the internal pressure in the electrolyser stack).

[0082] In the present case, all the electrolytic cells of the electrolyser stack 1 are identical to each other so that the following description of an electrolytic cell 10 is also applicable to the description of the other electrolytic cells 10.

[0083] Such an electrolytic cell 10 comprises a central membrane 11 which is framed by two electrodes 12a and 12b (an anode and a cathode, respectively) which are themselves framed by two spacers 16 (or "flow field material" in English) which are themselves framed by two bipolar plates 14. Furthermore, the electrolytic cell 10 also comprises a seal 13 (the existence of which has already been mentioned above) which is compressed between the two bipolar plates 14 of the electrolytic cell 10.

[0084] The membrane 11, the spacers 16 and the electrodes 12a and 12b being known from the prior art, they will not be detailed here.

[0085] The two bipolar plates 14 of an electrolytic cell 10 being identical to each other, the following description of one of the bipolar plates 14 is also applicable to the other of the bipolar plates 14 of the same electrolytic cell 10. The bipolar plate 14 is made of a material capable of withstanding the corrosive environment prevailing inside the electrolytic cell 10.

[0086] The bipolar plate 14 is for example nickel-based and is for example made of nickel or nickel-plated carbon steel. The bipolar plate 14 is further shaped so as to have two main faces: a first main face facing the inside of the electrolytic cell 10 in question and a second main face facing the outside of the electrolytic cell 10 in question.

[0087] It will be seen later that the bipolar plates 14 are asymmetrical (along a plane of symmetry passing through the center of the bipolar plate considered). Consequently, within the same electrolytic cell 10, the first face of the bipolar plate 14 which is being described is in front of a second face of another bipolar plate 14 identical to that which is being described. Within block 2, all the bipolar plates 14 are oriented in the same way. Subsequently, the X and Y axes are defined, which form a plane in which one of the main faces of the bipolar plate 14 extends, and the Z axis, which is normal to said XY plane.

[0088] When the bipolar plate 14 is in place in the electrolytic cell 10 which is itself in place in the electrolyzer stack 1, the Z axis here coincides with the general direction A.

[0089] The thickness of the bipolar plate 14 (along the Z axis) is less than its other dimensions.

[0090] The bipolar plate 14 is shaped so as to have a cross-section (in an XY plane) in any geometric shape (square, rectangular, disc-shaped, etc.). The bipolar plate here has a disc-shaped cross-section.

[0091] The external periphery of the bipolar plate 14 is defined by a first zone 21, a second zone 22 and a third zone 23.

[0092] The first zone 21 here extends over the entire circumference of at least one of the main faces of the bipolar plate 14. The first zone 21 is therefore a ring forming the external periphery of the main face.

[0093] The first zone 21 makes it possible to improve the resistance to the internal pressure prevailing within the electrolytic cell 1 of the bipolar plate 14 and makes it possible to improve the sealing of the electrolytic cell 10 with respect to the exterior of the electrolytic cell 1. In particular, said first zone 21 makes it possible to reinforce the resistance of the bipolar plate 14, in particular to the radial pressure loads exerted on the bipolar plate 14 (when the electrolytic cell 10 is arranged in the electrolytic cell 1). For example, the first zone 21 is dimensioned to meet the standard applicable to pressure tanks and, for example, the PED 2014 / 68 / EU standard.

[0094] The first zone 21 is preferably textured. For example, the first zone 21 has grooves, ridges, roughness, a rough appearance, etc. on at least one of the main faces of the bipolar plate 14 and preferably on both main faces of the bipolar plate 14.

[0095] On the other hand, the circular edge of the bipolar plate 14 (i.e. the surface connecting the two main faces of the bipolar plate 14 to each other) is very smooth, i.e. not textured.

[0096] The second zone 22 also extends circumferentially so as to be bordered externally by the first zone 21. The second zone 22 is coaxial with the first zone 21.

[0097] The second zone 22 here extends over the entire circumference of at least one of the main faces of the bipolar plate 14. The second zone 22 is therefore a ring.

[0098] The second zone 22 is smooth, i.e. not textured. This second zone 22 is located around the electrolyte supply channels and the channels for discharging the gaseous products resulting from the electrolysis.

[0099] This second zone 22 is less thick (the thickness being considered along the Z axis) than the first zone 21. For example, the bipolar plate 14 is shaped to have at least one shoulder between the first zone

[0100] 21 and the second zone 22. Preferably, the bipolar plate 14 is shaped to have two shoulders between the first zone 21 and the second zone 22. These two shoulders are here identical (as visible in figure 3a) and arranged at the level of the two main faces of the bipolar plate 14.

[0101] The bipolar plate 14 is thus symmetrical along a central plane of symmetry parallel to the X and Y axes at its first zone 21 and its second zone 22.

[0102] The narrowing between the first zone 21 and the second zone 22 makes it possible to achieve a different seal between the two zones.

[0103] The third zone 23 also extends circumferentially so as to be bordered externally by the second zone 22. The third zone 23 is coaxial with the second zone 22.

[0104] The third zone 23 here extends around the entire circumference of the bipolar plate. The third zone 23 is a ring.

[0105] This third zone 23 is less thick (the thickness being considered along the Z axis) than the second zone 22. For example, the bipolar plate 14 is shaped to have at least one shoulder between the second zone

[0106] 22 and the third zone 23.

[0107] Preferably, the bipolar plate 14 is shaped to have a single shoulder between the second zone 22 and the third zone 23. This shoulder is provided at the level of the first main face of the bipolar plate 14, that is, the one facing the inside of the electrolytic cell 10. This shoulder makes it possible to house the membrane 11.

[0108] Preferably, the second zone 22 and the third zone 23 extend in line with one another at the level of the second main face of the bipolar plate 14.

[0109] There is therefore no shoulder between the second zone 22 and the third zone 23 at the level of the second main face.

[0110] It is therefore understood that the second face of the bipolar plate 14 is devoid of such a shoulder so that the second face of the other bipolar plate of the electrolytic cell considered is devoid of such a shoulder. The membrane 11 is thus arranged between the two bipolar plates so as to be housed only in the shoulder of one of the two bipolar plates 14.

[0111] The bipolar plate 14 is thus asymmetrical according to a central plane of symmetry parallel to the X and Y axes if we consider the three aforementioned zones (as more visible in figures 3a and 3b and 3c).

[0112] The third zone 23 is entirely smooth (i.e. not textured) or partially smooth or entirely textured. Preferably, the third zone 23 is textured at the first main face of the bipolar plate 14. This makes it easier to hold the membrane 11 in place. For example, at the level of said first main face, the third zone 23 has grooves, ridges, roughness, a rough appearance, etc. Preferably, the third zone 23 is smooth at the level of the second main face of the bipolar plate 14. The thickness of the bipolar plate 14 (along the Z axis) therefore decreases as the shoulders progress, at the level of the junction between the first and second zones 21 and 22 but also between the second zone 22 and the third zone 23. The bipolar plate 14 is thus thicker at its first zone 21 than at its second zone 22 than at its third zone 23.

[0113] The first zone 21, the second zone 22 and the third zone 23 together form a crown 25. The crown 25 thus forms the circumferential periphery of the bipolar plate 14.

[0114] A central portion 24 of the bipolar plate 14 further extends so as to be bordered externally by the third zone 23. The central portion 24 is coaxial with the third zone 23.

[0115] The central portion 24 is solid. The central portion 24 thus forms a circular plate.

[0116] This central portion 24 is less thick (the thickness being considered along the Z axis) than the third zone 23. For example, the bipolar plate 14 is shaped to have at least one shoulder between the third zone 23 and the central portion 24. Preferably, the bipolar plate 14 is shaped to have two shoulders between the third zone 23 and the central portion 24. These two shoulders are here identical and formed at the level of the two main faces of the bipolar plate 14.

[0117] The central portion 24 may optionally itself have at least one shoulder so that its thickness (the thickness being considered along the Z axis) narrows towards the center of the plate.

[0118] The central portion 24 is therefore the thinnest part (the thickness being considered along the Z axis) of the bipolar plate 14.

[0119] The central portion 24 may be smooth or textured.

[0120] The central portion 24 acts as a current collector and will transmit it to the spacers 16 which are on either side of it. Furthermore, the bipolar plate 14 has orifices 15 passing right through it. These orifices 15 are dedicated to the supply of electrolytic solution and the exhaust of the electrolysis products.

[0121] For example, the bipolar plate 14 has between three and six orifices. The orifices are for example associated two by two, the pairs of two orifices being distributed homogeneously around the circumference of the bipolar plate 14. The bipolar plate can thus have three pairs of two orifices.

[0122] For example, at least one of the orifices 15 is provided in the second zone 22. In the present case, all of the orifices 15 are provided in the second zone 22.

[0123] The orifices may have a circular, oblong, or other cross-section. For example, at least one of the orifices 15 has an oblong cross-section.

[0124] In a manner known per se, one or more additional orifices extend from the orifice 15 towards the central portion 24 in order to allow the supply of electrolytic solution and the escape of the electrolysis products inside the electrolytic cell. These additional orifices extend for example radially. In order to prevent the seal 13 from being able to obstruct the orifices, these are preferably provided at least in part on the surface of the bipolar plate 14 and closed laterally by one or more plates which will themselves be in contact with the seal.

[0125] In reality, the role of said central portion 24 is not really to support high pressure forces unlike the crown 25. The central portion 24 thus has the main role of serving as a support for the components stacked within the electrolytic cell.

[0126] 10 namely the spacers 16, the electrodes 12a and 12b and the membrane 11. The forces are therefore equal on the two faces of the central portion 24.

[0127] The bipolar plates 14 therefore have a particular geometry. The thickness of each aforementioned zone varies between one and the other from a few tenths of a millimeter to several millimeters. The thickness of a aforementioned zone also has a variable value under the effect of the thermal expansion of the bipolar plate 14 (the variability of the thickness of each zone due to the thermal expansion thus also varying from one zone to another).

[0128] As already indicated within the electrolytic cell 10, the two bipolar plates 14 compress a seal 13 between them.

[0129] 11 It should be noted that within the electrolyser stack 1, all the bipolar plates 14 are separated two by two by a seal 13 (since each bipolar plate 14 acts as a cathode for one electrolytic cell 10 and as an anode for another electrolytic cell 10 immediately adjacent).

[0130] Advantageously, the two bipolar plates 14 compress a single seal 13 between them.

[0131] Advantageously, all the seals 13 of the electrolytic cells 10 are identical within the cell block 2 so that the following description of one of the seals 13 is also applicable to the other seals 13 of the other electrolytic cells 10.

[0132] The main functionalities of the seal 13 are as follows: i) ensuring the sealing of each electrolytic cell 10 with respect to the outside of the electrolyzer stack 1, ii) ensuring the sealing of the channels carrying a gas which is generated within the block 2 with respect to those carrying another gas generated within the block 2, iii) ensuring the sealing of the chambers which are the seats of the electrolysis reactions where the two aforementioned gases are generated to isolate them from each other but also ensuring the sealing towards the channels mentioned just before, iv) acting as an electrical insulation layer between two adjacent bipolar plates 14 and v) defining the thickness to which the electrolytic cells 10 are compressed in the Z direction.

[0133] Advantageously, a single seal 13 is compressed between two adjacent bipolar plates 14 within the same electrolytic cell 10.

[0134] Preferably, the seal 13 is shaped so as to have a square or rectangular cross-section (along a transverse cutting plane).

[0135] Seal 13 is therefore called a “flat seal”.

[0136] Preferably the seal 13 is shaped correspondingly to the shape of the crown 25 of the associated bipolar plate 14.

[0137] In the present case, the seal 13 is generally shaped like a ring, the associated bipolar plate 14 being disc-shaped.

[0138] It is noted that the seal 13 is pierced with a plurality of holes.

[0139] This ensures the supply of block 2 and the evacuation of fluids from block 2. For example, the holes made in the seal 13 correspond to those made in the zone 22 of the bipolar plate 14.

[0140] The joint 13 is shaped to have a diameter (of its cross-section) as constant as possible over all its internal and external circumferences and / or a thickness (along the Z axis) as constant as possible over its entire section (but also from one joint 13 to another).

[0141] This makes it possible to improve the efficiency of the electrolytic cells 10 of the electrolyser stack 1. In particular, this makes it possible to have faces of the seal 13 parallel to each other and to the main faces of the facing bipolar plates 14.

[0142] This further improves the sealing of the assembly.

[0143] The tolerance on the dimensions of the gasket 13 will depend on the application for which it is intended (for example the tolerance is + / -0.1 millimeter in thickness).

[0144] As we have said, and as more visible in figure 3c, the seal 13 is compressed between two adjacent bipolar plates 14 and more precisely between the two external peripheries of the main faces opposite said bipolar plates 14 and more precisely between the two crowns 25 opposite said bipolar plates 14.

[0145] Due to the particular geometry of the bipolar plates 14 at their external periphery, and in particular their crown 25, the bipolar plates 14, by compressing the seal 13, deform it in turn so as to delimit and characterize said seal 13 into three distinct portions.

[0146] On the other hand, the seal 13 is not compressed between the central portions 24 of said two bipolar plates 14.

[0147] The diameter of the seal 13 (according to a cross-section) is such that the seal 13 extends from the lateral edge of the bipolar plates 14 to the connection between the third zones 23 and the central portions 24 (preferably protruding from the third zones 23).

[0148] Thus, each portion of the present seal 13 fulfills a distinct sealing function and is characterized by a specific compression level, the latter varying from one portion to another. The physical and mechanical consequence is the variable reduction in thickness of said seal 13 depending on the portion considered. Thus, when the seal 13 is in the rest state, it has a conventional annular shape and a substantially single initial thickness.

[0149] When the seal 13 is compressed between two plates 14: between the first zones 21 of the two bipolar plates 14, the seal 13 has a first corresponding portion that is textured because it matches the geometry of said first zones 21, between the second zones 22 of the two bipolar plates 14, the seal 13 has a second corresponding portion that is smooth, the seal 13 then also having a greater thickness than at its first portion, between the third zones 23 of the two bipolar plates 14 and the membrane 11, the seal 13 has a third corresponding portion that is smooth and / or grooved.

[0150] At its first portion, the seal 13 is directly compressed between the first two zones 21 (without intermediate component).

[0151] At its second portion, the seal 13 is directly compressed between the two second zones 22 (without intermediate component).

[0152] In contrast to its third portion, the seal 13 is not directly compressed between the two third zones 23. Indeed, the membrane 11 is also present between these two third zones 23. Consequently, the seal 13 is compressed on one of its faces directly by one of the third zones 23 and on the other of its faces directly by the membrane 11 which is itself directly compressed by the third zone 23 of the opposite bipolar plate 14.

[0153] At its third portion, the seal 13 then has a thickness substantially less than that of its second portion, the membrane 11 filling the remainder of the space between the two third zones 23. The sealing of the membrane 11 is thus obtained.

[0154] The seal 13 is thus distributed over its entire height (along the X axis) between its three portions and therefore between the three zones of the crowns 25.

[0155] Consequently, the part of the electrolytic cell 10 located at the level of the first zones 21 of the two bipolar plates 14 and the first portion of the seal 13 makes it possible to prevent the electrolyte solution or gases from escaping from the electrolyser stack 1, in other words it is dedicated to ensuring the sealing of the electrolytic cell 10 with respect to the external environment. For example, it ensures a leak rate less than or equal to 10-3 milligrams per meter per second - mg / (m*s) when the leak rate is measured by means of a helium gas - and preferably a leak rate less than or equal to 10-4 mg / (m*s).

[0156] This first part is characterized by the presence of textures on the bipolar plates 14 in which the seal 13 deforms. In particular, the seal 13 can, by deforming, fill the hollows of the first portions of the bipolar plates 14 and thus reinforce the sealing of the electrolytic cell 10. Indeed, these textures constitute an additional obstacle to the gases and other substances present, from finding the path to the outside of the electrolyzer stack 1. This presence of textures also plays a role which promotes the friction between the electrolytic cells 10 and therefore the self-maintenance of the plurality of electrolysis cells 10 stacked to form the block 2. This advantage is reinforced when the block is horizontal in operation.

[0157] For example, the compression of the seal 13 is such that the seal 13 reaches at the first part a maximum thickness (along the Z axis) of 94% and preferably 78% and preferably 75% of its starting thickness (when it is in its resting state flat on a flat surface without external stress). The starting thickness is for example equal to or greater than 3.0 millimeters. Preferably, this starting thickness does not exceed 3.5 millimeters.

[0158] The second part of the electrolytic cell 10 located at the level of the second zones 22 of the two bipolar plates 14 and of the second portion of the seal 13 makes it possible to avoid an exchange between the channels carrying hydrogen and oxygen in the electrolytic cell 10 or from the electrolytic cell 10 itself (from the third zone 23 and the central portion 24) towards these said channels.

[0159] For example, the compression of the seal 13 is such that the seal 13 reaches at the second part a thickness (along the Z axis) of between 92 and 97% of its starting thickness (when it is in its resting state flat on a flat surface without external stress) and preferably a thickness of 92% of its starting thickness. In all cases, the seal 13 is less compressed than at the first part and therefore has a greater thickness than at the first part.

[0160] The widening of the seal 13 between the first zones 21 and the second zones 22 makes it possible to achieve a different seal between the first zones 21 and the second zones 22. In particular, the seal between the first zones 21 and the second zones 22 is of good quality.

[0161] The third part of the electrolytic cell 10 located at the level of the third zones 23 of the two bipolar plates 14 and the third portion of the seal 13 makes it possible to accommodate the membrane 11 as has already been indicated. This third part therefore ensures the seal between the anode and cathode compartments of the electrolytic cell 10.

[0162] We therefore note that the membrane 11 like the seal 13 are then compressed between the two bipolar plates 14 at the level of this third part: the seal 13 is thus superimposed on the membrane 11 on this part of the electrolytic cell 10.

[0163] This ensures very good sealing around the membrane 11 on its perimeter and in the direction of the fluid supply and extraction channels.

[0164] The third portion of the seal 13 thus defines a third compression zone intended to maintain the membrane 11 and ensure its sealing around its perimeter.

[0165] For example, the compression of the seal 13 is such that the seal 13 reaches at the level of the third part a thickness (along the Z axis) of between 86 and 92% of its starting thickness (when it is in its resting state flat on a flat surface without external stress) and preferably a thickness of between 88 and 92% of its starting thickness and preferably a thickness of 90% of its starting thickness.

[0166] According to another aspect, the seal 13 is made of monomeric material or polymeric material and for example plastic material.

[0167] For example, the seal 13 is made of a material of the polytetrafluoroethylene or polytetrafluoroethylene type (commonly abbreviated PTFE or better known under the trade name Teflon - registered trademark).

[0168] Preferably, the material is made of or based on or of the type polytetrafluoroethylene or polytetrafluoroethylene with at least one filler added. For example, the filler is fiberglass. For example, said material is reinforced polytetrafluoroethylene. For example, reinforced polytetrafluoroethylene is polytetrafluoroethylene reinforced with glass fibers or reinforced polytetrafluoroethylene is polytetrafluoroethylene reinforced with carbon fibers.The properties of the seal 13 described are defined below: good behavior of the material and preservation of its good mechanical properties at the operating temperature of the electrolytic cell 10 which is nevertheless high (typically of the order of 90 to 95 degrees Celsius) and this over the long term; resistance to the corrosive environment inside the electrolytic cell 10 and this over the long term; good sealing properties; good electrical insulation properties (given by good electrical resistance) and this even at the operating temperature and in contact with the electrolyte solution; little creep allows a good longevity of the stack of electrolytic cells 10; slight creep behavior all the same in order to best match the geometrical particularities of the seating zone 21 of the seal 13; uniformity of the thickness (along the Z axis).

[0169] According to one option, the end seal arranged between the first distribution plate 5 and the first bottom plate 3 is made of the same material as the seal 13 of an electrolytic cell 10 which has just been described. The end seal is for example identical to said seal 13. Said end seal is optionally made of monomeric material or polymeric material and for example plastic material. According to one option, the layer of electrically insulating material between the first bottom plate 3 and the first distribution plate 5 is made of the same material as the end seal arranged between the first distribution plate 5 and the first bottom plate 3. According to one option, the layer of electrically insulating material between the first bottom plate 3 and the first distribution plate 5 is made of the same material as said seal 13. Said layer is optionally made of monomeric or polymeric material and for example plastic material.According to one option, the end seal arranged between the second distribution plate 6 and the second bottom plate 4 is made of the same material as the seal 13 of an electrolytic cell 10 which has just been described. Said end seal is for example identical to said seal 13. Said end seal is optionally made of monomer material, polymer material and for example plastic material.

[0170] According to one option, the pellet arranged on the internal face of the first distribution plate 5 is a layer of material directly applied to the first distribution plate 5 or is formed by powder deposition (by Halar (registered trademark) deposition for example).

[0171] The electrolytic cell 10 thus described has very good sealing due to the specific compression of the seal 13 between the bipolar plates 14.

[0172] It is also noted that the electrolytic cell 10 is made watertight thanks to a single seal 13 and this with three different sealing and compression zones.

[0173] The use of a single seal 13 made of plastic (and no longer of elastomer as in the prior art) also makes it possible to improve the sealing of the electrolyser stack. In fact, the seal 13 is more resistant, even over a long period, to the corrosive environment prevailing inside the electrolyser stack 1.

[0174] The seal 13 is thus made of a hard material resistant to the strong mechanical compressions to which the electrolyser cell is subjected.

[0175] A method of assembling the electrolyzer stack 1 will now be described.

[0176] In a first step, subassemblies are individually constructed, each subassembly being composed by assembling two spacers 16 and two electrodes 12a, 12b on either side of a bipolar plate 14. Each subassembly strictly speaking constitutes two adjoining electrolytic half-cells.

[0177] In a second step, said subassemblies are stacked successively, separated from each other by a membrane 11 and a seal 13, forming said electrolytic cells 10 electrically connected in series. The last electrolytic cell 10 at one end of the block 2 is covered by the second distribution plate 6, itself covered by the second bottom plate 4 and the last electrolytic cell 10 at the other end of the block 2 is covered by the first distribution plate 5, itself covered by the first bottom plate 3, thus delimiting the electrolyser stack 1.

[0178] In a third step, the newly assembled electrolyser stack 1 is put into compression using the tie rods 7, nuts 8 and spring washers 9.

[0179] For this purpose, the electrolyser stack 1 (and therefore the different layers of the electrolytic cell 10 together as well as the seals 13) is pre-tightened.

[0180] This third step is preferably carried out at room temperature. For example, this third step is carried out at a temperature between 15 and 25 degrees Celsius and for example between 18 and 22 degrees Celsius.

[0181] Pre-tightening is obtained for example by acting on the nuts 8 of the tie rods 7. Preferably, several nuts 8 are tightened simultaneously. Preferably, the nuts 8 are all grouped together, each group being tightened one after the other and the nuts within the same group being tightened simultaneously. Preferably, the tightening of the groups is carried out in a staggered or star-shaped pattern. For example, one group of nuts 8 may be tightened at the same time, before moving on to the next group whose nuts are located as close as possible to the nuts of the first group 8, and so on. Preferably, during this phase all the nuts 8 are tightened.

[0182] In the third step, several 8 nuts are tightened at the same time, but not all 8 nuts in the block are tightened at the same time.

[0183] This makes it possible to ensure a reduction in the thicknesses of the joints 13 in a relatively homogeneous and uniform manner over the entire circumference of the different joints.

[0184] Pre-tightening can be achieved, for example, by means of hydraulic means, for example hydraulic cylinders.

[0185] During this third step, the electrolyser stack is preferably tightened to reach a threshold characteristic of a targeted initial compression ratio of at least one of the seals 13 and preferably of all the seals 13.

[0186] This threshold may be defined, for example, at least under one of the following conditions:

[0187] - at least one of the joints (and preferably all the joints 13), at the end of the first phase, must ensure contact between the two bipolar plates 14 and the membrane 11 within a given cell, and / or - at least one of the joints (and preferably all the joints 13), at the end of the first phase, must have a compression rate of between 25 and 50% of a final compression rate targeted for at least one of the joints 13 and preferably for all the joints 13.

[0188] The threshold can thus be a target thickness of at least one of the joints or a target thickness of several joints or a target thickness of the electrolyser stack 1 or a target clamping force of the electrolyser stack. To estimate whether the threshold is being approached, a thickness of at least one of the joints or a thickness of the electrolyser stack or the clamping force applied to the electrolyser stack is measured correspondingly during the first phase, for example.

[0189] In particular, this third step includes a series of tightening sessions so that the tightening of the electrolyser stack is carried out in stages. Preferably, at the end of each stage, the distance from the threshold is estimated in order to control the tightening force on the next stage.

[0190] In a fourth step, the electrolyser stack 1, and therefore the block 2, are then subjected to successive tightening cycles.

[0191] A tightening cycle consists of the following phases.

[0192] First phase: Heating of the electrolyzer stack 1. This first phase is carried out for example by injecting a gas or a liquid (such as steam, and for example water vapor, or a hot liquid, and for example hot water) through a portion of the inlet and outlet orifices of the bottom plate 4 to heat the entire interior of the electrolyzer stack 1, and in particular the seals 13. Alternatively, the gas or liquid may be at room temperature inside the electrolyzer stack. For example, heating means may be temporarily introduced into the electrolyzer stack 1 in order to heat the gas or liquid (for example, the heating means may comprise one or more resistors). Optionally, the heating means will be temporarily introduced into the electrolyzer stack 1 through the orifices 15 of the bipolar plates 14.

[0193] Second phase: Tightening of the electrolyser stack 1 (and therefore of the different layers of the electrolytic cell 10 between them as well as the seals 13).

[0194] The tightening is obtained for example by acting on the nuts 8 of the tie rods 7. Preferably, several nuts 8 are tightened simultaneously. Preferably, the nuts 8 are all grouped together, each group being tightened one after the other and the nuts within the same group being tightened simultaneously. Preferably, the tightening of the groups is carried out in a staggered or star-shaped pattern. For example, one group of nuts 8 can be tightened at the same time, before moving on to the next group whose nuts are located as close as possible to the nuts of the first group 8, and so on. Preferably, during this phase all the nuts 8 are tightened.

[0195] During the second phase, several 8 nuts are acted on at the same time, but not all the 8 nuts in the block are tightened at the same time.

[0196] This makes it possible to ensure a reduction in the thicknesses of the joints 13 in a relatively homogeneous and uniform manner over the entire circumference of the different joints.

[0197] The tightening can be carried out for example by means of hydraulic means and for example hydraulic cylinders. It is understood that the tightening is carried out hot due to the previous phase and no longer at room temperature as in the third step.

[0198] Third phase: Cooling of the electrolyser stack 1.

[0199] This cooling can be natural (by stopping the heating of the electrolyser stack 1, the latter being in contact with the air at ambient temperature which will allow natural cooling thereof) and / or forced [for example by injecting a gas or a liquid (such as cold water) through part of the inlet and outlet orifices of the bottom plate 4 to cool the entire interior of the electrolyser stack 1, and in particular the seals 13 / by ventilation / etc.].

[0200] Fourth phase: Tightening of the electrolyser stack 1 and therefore of the different layers of the electrolytic cells 10 and the seals 13.

[0201] This tightening is carried out like the second phase but at room temperature as in the third pre-tightening step (the temperature ranges indicated can also be applied here).

[0202] In the fourth step, a series of hot and then room temperature tightenings of the electrolyser stack 1, and therefore of the block 2, are thus carried out. Given that the hot tightening is carried out at a higher temperature than the room temperature tightening, it can also be said that a series of hot and then cold tightenings of the electrolyser stack 1, and therefore of the block 2, are carried out.

[0203] The second phase (especially in its first iteration if phases 1 to 4 are repeated several times) allows a significant reduction in the individual thickness of the different joints 13.

[0204] Phases 1 to 4 are preferably repeated again until a threshold characteristic of a targeted final compression ratio of at least one of the seals 13 and preferably of all the seals 13 is reached.

[0205] The threshold may be defined, for example, by taking into account the sealing performance targeted on at least one of the seals 13, and preferably all the seals, and preferably the electrolytic cell 1 as a whole, and / or the geometric compression targeted on the electrolytic cell 1 so that the electrical contacts are satisfactory to achieve a given efficiency and / or a given electrical continuity, and / or the mechanical stability targeted on the material making up the seal(s) 13 so that the creep phenomenon does not unduly penalize the sealing of the electrolytic cell 1.

[0206] Preferably, the aforementioned threshold is linked to at least one compression rate of at least one of the seals 13 and preferably of all the seals 13.

[0207] Preferably, the aforementioned threshold is linked to at least the compression rate of the portion of at least one of the joints 13 (and preferably of all the joints 13) linked to the first zones 21 of the facing bipolar plates 14.

[0208] More precisely, the aforementioned threshold is linked to the compression rates, defined above in the application, linked to the different portions of at least one of the joints and preferably of all the joints 13.

[0209] It should be noted that from the first iteration, the joints 13 have a thickness close to their target value. The following iterations thus aim more at the disappearance of the plastic behavior of the joints in their area of ​​use.

[0210] Preferably, after each tightening phase (second phase and fourth phase) at least one parameter from among the following parameters is measured: a thickness of at least one of the joints, a thickness of the electrolyzer stack or of the block, a distance between the bottom plates 3 and 4, a tightening force applied to the electrolyzer stack. For example, after each tightening phase, the thickness of all the joints 13 is estimated by measuring the distance between the bottom plates 3 and 4 or the tightening force applied to the electrolyzer stack 1.

[0211] Role This allows to control the repetition of phases 1 to 4 by estimating the progression up to the final threshold. For example the final threshold is a target thickness value of the electrolyser stack 1. For example, after each tightening phase, the thickness of the electrolyser stack 1 is checked. Optionally the thickness of block 2 is measured by measuring the thickness between the bottom plates 3 and 4 and this at different points of the circumference of block 2; then the different values ​​obtained are averaged to obtain an average thickness of block 2; from the number of cells and the thickness of the different elements per cell we deduce the average thickness of each of the joints 13). We deduce a ratio Hn+l / Hn with Hn the thickness delta to be carried out to reach the target thickness (here the final threshold) following the tightening phase which has just been carried out and Hn+1 the thickness delta to be carried out to reach this target thickness during the following tightening phase.This ratio allows the progress of the fourth stage to be monitored. Preferably, the fourth stage is implemented so that this ratio is maintained within a given range throughout the fourth stage. Preferably, when the second phase is implemented for the first time, a Hn+l / Hn ratio of less than 0.5 (meaning that the thickness delta has been reduced by more than 50%) and preferably less than 0.4 (meaning that the thickness delta has been reduced by more than 60%) is targeted. For example, a Hn+l / Hn ratio of between 0.5 and 0.25 and preferably between 0.4 and 0.25 is targeted.

[0212] Role 2

[0213] This makes it possible to estimate the areas of the electrolysis cell 1 with abnormally greater thicknesses than the other areas of said cell. Therefore, during the following tightening phase, it is possible to adapt the tightening by targeting the nuts via which it is necessary to carry out a privileged tightening to absorb an area with an abnormally greater thickness than the other areas of the electrolyser cell 1. It is thus possible to correct a parallelism defect of the bipolar plates 14 and / or the cells during the various tightening phases. This is essential to ultimately ensure good electrical contact between the different electrolytic cells 5 over the entire surface of said cells. This also makes it possible to maintain an electrolysis cell 1 that is as straight and as centered as possible on its Z axis. This also makes it possible to have the bottom plates 3 and 4 well aligned and parallel to each other.For example, the inventors were able to observe that a possible parallelism defect between the bottom plates 3 and 4 was less than a millimeter for a 5 meter long electrolyte cell (length taken on the Z axis).

[0214] Preferably, the first role and / or the second role are also implemented for the third pre-tightening step.

[0215] Preferably, the heating of the seal 13 is done by steam (by baking). This makes it possible to transport a large quantity of energy by a reduced quantity of fluid corresponding to the size of the channels. More precisely, the thickness of the seal 13 is permanently reduced to reach the predefined compression ratios. Furthermore, the plastic behavior (or creep) of said seal 13 is attenuated over the hot and room temperature tightening cycles until reaching a range of elastic behavior. In this way, the seal 13 exhibits, at the end of this fourth step, a linear deformation behavior. The latter makes it possible (thanks to the counterbalancing force induced by the elastic washers 9) to ensure sealing for the different zones of the bipolar plates 14, in particular in view of the expansions and the pressure forces applied to the electrolyzer stack 1.

[0216] This removes the plastic character of joint 13.

[0217] The thickness (along the Z axis) of the joint 13 is therefore gradually but drastically reduced by plastic deformation of said joint 13. Figure 5 makes it possible to visualize this reduction in thickness of the joint 13 during the different stages and phases of the assembly process described. The curve thus illustrates the evolution of the average thickness of the joint 13 (determined as indicated above or by another method) during the different stages and phases of the assembly process described, the value 100% corresponding to the target thickness reduction.

[0218] For example, at least on certain portions of the seal 13, the thickness of the seal 13 is reduced by at least 10% or even at least 15% or even at least 20% or even at least 25%. This makes it possible to limit the creep of the seals 13 during actual operation of the electrolyzer stack 1. In this way, the seals 13 ensure very good sealing of the electrolyzer stack 1, even over time on the scale of 10 or 20 years.

[0219] Cleverly, part of the tightening is carried out hot, which allows the softer (less hard) nature of the seal material 13 to be taken advantage of at high temperatures.

[0220] Such an assembly with thick distribution plates 5 and 6 and thin, flat bipolar plates 14 allows homogeneity of the current in all the electrolytic cells 10 of the electrolyzer stack 1 while the voltage is different at the terminals of each electrolytic cell 10 and the current is only connected to one or more points at the periphery of each distribution plate 5 and 6.

[0221] Furthermore, the bipolar plates 14 are parallel to each other within the block 2 thanks to their particular shape and the good tightening of each joint 13. This further improves the homogeneity of the current in all the electrolytic cells 10.

[0222] The assembly method which has been described allows in particular each joint 13: to deform according to the geometry imposed by the bipolar plates enclosing it, to sink into the textures of the first zones 21 in order to fill them, to deliberately and prematurely age the material composing it, to eliminate as best as possible the plastic component, to bring its material into a range of elastic behavior (centered on an operating point of the electrolyzer cell). to reach the desired tightening value combining both the desired seals and the electrical contacts between the different components making it possible to achieve the envisaged energy performances.

[0223] At the end of the fourth stage, the temperature and pressure inside the electrolyser stack 1 may change, but the seals will advantageously always remain within the elastic range obtained. The nominal operating point of the electrolyser stack is, for example, 85 degrees Celsius under 3 Megapas cal s.

[0224] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0225] The assembly method described will advantageously apply to all types of electrolyzer stack 1, regardless of their thermal and mechanical characteristics, their number, their size or the nature of the material constituting said electrolyzer stack 1.

[0226] The end seal(s) may be different from seals 13.

[0227] The electrolyzer stack 1 may be assembled differently from what has been described.

[0228] Although here the electrolytic cell is cooled (naturally and / or forcibly) to room temperature, the electrolytic cell may be cooled to a value higher than room temperature. For example, the electrolytic cell may be cooled so that its temperature is lower than 35 degrees Celsius and, for example, between 15 and 35 degrees Celsius and, for example, between 20 and 35 degrees Celsius. Cold tightening may thus be carried out at a different temperature between two successive cold tightenings (provided that the electrolytic cell is at a temperature lower than that of the hot tightening and close to room temperature without preferentially falling below 15 degrees Celsius, which could hinder the plasticity of the joint material) and / or at a different temperature than the first tightening phase.Although the assembly process here allows the assembly of an electrolytic cell, the assembly process may also allow the assembly of other cell stacks such as a heat exchanger, a press, a filter press, etc., and preferably on cell stacks that are to be used over long periods and / or require high levels of sealing.

[0229] The stack of elements can be used horizontally, vertically, or in any other position. The stack of elements can be assembled horizontally, vertically, or in any other position. Preferably, the stack of elements will be assembled vertically and used horizontally.

Claims

CLAIMS 1. Method of assembling a stack of elements, comprising the steps of: Individually assembling sub-assemblies of said elements, Assembling the sub-assemblies together by arranging a joint between each sub-assembly to form the stack of elements, Applying successive heating and cooling phases to the stack of elements by applying at least one tightening of the stack of elements between two different heating and cooling phases.

2. Method according to claim 1, in which the stack of elements is an electrolyzer stack, the subassemblies thus being pairs of electrolytic half-cells.

3. Method according to one of the preceding claims, comprising a step of pre-tightening the stack of elements before the step of applying successive heating and cooling phases to the stack of elements by applying at least one tightening of the stack of elements between two different heating and cooling phases.

4. Method according to claim 3, in which the pre-tightening step is carried out in stages.

5. Method according to one of the preceding claims, in which the elements are heated by injecting steam into the elements.

6. The method of claim 5, wherein the vapor is water vapor.

7. Method according to one of claims 1 to 4, in which the elements (10) are heated by injecting hot water into the elements.

8. Method according to one of the preceding claims, in which the cooling of the elements is forced.

9. Method according to one of the preceding claims, in which the cooling of the elements is natural.

10. Method according to one of the preceding claims, in which at least two iterations of the following phases are carried out: Heating the interior of the stack of elements, Clamping the different elements together, Cooling the different elements together, Tightening the different elements together.

11. Method according to claim 10, in which the iterations are stopped when at least one predefined compression rate of at least one joint of the element stack is reached.

12. Method according to one of the preceding claims, in which at least one subassembly is assembled by fixing two bipolar plates (16) together so as to clamp at least one joint (13) between the two plates.

13. The method of claim 12, wherein a single seal is clamped between the two bipolar plates.

14. Method according to one of the preceding claims, in which the stack of elements is arranged vertically and / or horizontally.

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