GAS DISTRIBUTION ARRANGEMENT, ESPECIALLY FOR ELECTROLYZERS OR FUEL CELLS OF THE HIGH-TEMPERATURE SOLID OXIDE TYPE

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a gas distribution assembly, in particular for electrolysers or high-temperature solid oxide fuel cells.

[0002] The present invention relates to the general field of high temperature electrolysis (HTE), in particular high temperature steam electrolysis (HTSE), respectively designated by the English names " High Temperature Electrolysis » (HTE) and « High Temperature Steam Electrolysis » (HTSE).

[0003] More specifically, the invention relates to the field of high-temperature solid oxide electrolysers, usually designated by the acronym SOEC (for " Solid Oxide Electrolyzer Cell " in English).

[0004] It also concerns the field of high-temperature solid oxide fuel cells, usually designated by the acronym SOFC (for "solid oxide fuel cells"). Solid Oxide Fuel Cells " in English).

[0005] Thus, more generally, the invention refers to the field of solid oxide stacks of the SOEC / SOFC type operating at high temperature.

[0006] More specifically, the invention relates to a gas distribution assembly comprising a first plate, such as a gas distribution plate, and a second plate, such as an end plate of a solid oxide stack of the SOEC / SOFC type operating at high temperature, and a sealing interface device for ensuring sealing between the first and second plates for gas distribution.

[0007] In particular, the invention relates to a sealing interface device for ensuring the sealing of a stack (or " stack » in English) solid oxide SOEC / SOFC type mounted on a gas distribution plate, also called collector or " manifold» according to English terminology. As is well known, the gas distribution plate or manifold allows the sending and recovery of gases for the anode circuit and the cathode circuit of the SOEC / SOFC type solid oxide stack. STATE OF THE ART

[0008] SOEC / SOFC type solid oxide stacks, whether on manufacturing / packaging benches or integrated in fine within industrial systems, must be connected to gas supply circuits of a fixed installation.

[0009] In order to simplify the integration, assembly and disassembly of the stacks, it is known to make such a connection via easily removable mechanical interfaces, excluding welded solutions. It is then necessary to provide a seal between the gas distribution device of the fixed installation and the SOEC / SOFC type solid oxide stack.

[0010] Achieving such a seal is complex: the seals must withstand high temperatures (around 600°C to 1000°C), and also provide electrical insulation between the gas distribution device of the fixed installation and the SOEC / SOFC type solid oxide stack.

[0011] It is known, for example, to use, to ensure the seal between the gas supply circuits, sealing gaskets composed of materials of mineral origin (clay, talc, mica, ceramic, glass-ceramic) compressed by means of external mechanical clamping systems. Flat compressive sealing gaskets formed from compacted vermiculite powder are, for example, used around the communication orifices for the gas supply or outlet of a gas distribution plate or manifold.

[0012] These seals provide, in addition to their sealing function, an electrical insulation function between the mechanical interfaces between which they are mounted.

[0013] However, such seals require the application of a significant compressive force to obtain sufficient sealing by densification of the material and adhesion to the facing interfaces. A tightening stress of the order of MPa, or even several tens of MPa, is required to achieve compression rates of the seal, allowing sealing to be ensured.

[0014] Conversely, excessive crushing of the seal can lead to its rupture, which can compromise its sealing function.

[0015] Furthermore, a clamping stress of several MPa at high temperature can generate a bending load on the end plates of the stack, this bending which can lead to plastic deformation of these end plates, the stack and / or the gas distribution plate. When numerous assemblies and disassemblies of a stack on the gas distribution plate are carried out, particularly on conditioning benches, the flatness of the gas distribution plate or manifold can deteriorate over time. The risk of degradation increases even more when the width of the base of the stacks increases.

[0016] The gas distribution plate or manifold, located at the heart of the conditioning bench, is a component that is difficult to replace. Conditioning a stack on a deformed manifold plate, in addition to causing sealing problems, will result in increasingly significant deformations at the end plates of the stacks.

[0017] More generally, such deformations can be observed in a gas distribution assembly having parallel plates coupled under pressure by a clamping device, with a sealing interface device comprising a seal around a communication orifice of one of the plates for the supply or outlet of gas to the other plate. EP3016192 A1 and EP3667793 A1 describe a gas distribution assembly for a fuel cell comprising spacers in combination with sealing gaskets. STATEMENT OF THE INVENTION

[0018] The present invention aims to at least partially remedy the drawbacks mentioned below.

[0019] To this end, the present invention relates to a gas distribution assembly comprising: a first plate and a second plate, the first plate comprising at least one communication orifice for the supply or outlet of gas positioned opposite a corresponding communication orifice of the second plate, said first and second plates extending parallel to each other; a clamping device for coupling under pressure said first and second plates in a coupling plane parallel to said first and second plates; and a sealing interface device comprising at least one seal arranged in said coupling plane around said at least one communication orifice of said first plate.

[0020] According to the invention, the sealing interface device comprises a spacer arranged in said coupling plane between the first and second plates, said spacer and the sealing gasket(s) forming a sealing interface having two planes of symmetry perpendicular to each other and perpendicular to said coupling plane, the thickness of the sealing gasket(s) before coupling under pressure of said first and second plates being strictly greater than the thickness of said spacer.

[0021] The spacer thus makes it possible to limit the crushing of the sealing gasket(s) during the coupling under pressure of the first and second plates of the gas distribution assembly, and therefore the movement of the first and / or second plates crushing the sealing gasket(s). The symmetrical arrangement of the sealing interface in the coupling plane and the limitation of the crushing of the sealing gasket(s) by means of the spacer make it possible to reduce the risks of bending of the first and second plates of the gas distribution assembly during the coupling under pressure.

[0022] The deformation of the first and second plates is thus limited and their flatness can be maintained over time.

[0023] The risks of bending of the plates of the gas distribution assembly are thus reduced during mechanical compression of the stack and the various elements of the sealing interface device.

[0024] The gas distribution assembly may further comprise one or more of the following features taken individually or in combination.

[0025] Advantageously, the area of ​​the surface formed by the spacer in said coupling plane is greater than the area of ​​the surface formed by the sealing gasket(s) in said coupling plane.

[0026] The support surface in the coupling plane formed by the spacer, greater than that of the sealing gasket(s), makes it possible to avoid excessive crushing of the sealing gasket(s), even under a tightening stress greater than the value required to compress the sealing gasket(s).

[0027] In one embodiment, the stiffness of the material constituting the spacer is greater than the stiffness of the material constituting the sealing gasket(s).

[0028] The spacer thus provides a more rigid mechanical support than the sealing gasket(s) in the sealing interface, limiting the displacement of the first and second plates during their coupling under pressure. Such support in the coupling plane makes it possible to limit (geometrically) the bending moment of the first and second plates. In an advantageous embodiment, the spacer comprises at least one frame-forming portion extending at the periphery of a sealing gasket. This frame-forming portion combines with the sealing gasket to provide reinforced sealing around the communication orifice.

[0029] In a preferred embodiment, when the sealing interface device comprises several seals, said spacer comprises a support portion arranged equidistant from said seals.

[0030] The support portion of the spacer is thus placed at the shortest possible distance from the various seals in the sealing interface. The bending moment applied to the first and / or second plates is thus reduced when they are coupled under pressure.

[0031] In practice, said spacer comprises several frame-forming portions extending to the periphery of said several sealing joints respectively.

[0032] Advantageously, said spacer is formed from a single-piece flat structure comprising said frame-forming portions.

[0033] The one-piece planar structure makes it easier to position the spacer and the seals in the coupling plane of the first and second plates. By varying the surface area of ​​the one-piece planar structure in the coupling plane and the stiffness of the material forming the one-piece planar structure, it is possible to control the stiffness of the spacer according to the desired crushing rate for the seals.

[0034] In practice, the dimensions of an opening formed by each frame-forming portion extending at the periphery of a seal in the coupling plane are strictly greater than the dimensions of said seal in said coupling plane.

[0035] A clearance is thus formed between the seal and the frame portion of the spacer, allowing free expansion of the seal in the coupling plane when the seal is crushed.

[0036] In a particular embodiment, each frame portion is provided with one or more projecting fingers extending towards said seal and in contact with said seal.

[0037] The projecting finger(s) provide support for the seal in the spacer, facilitating the installation of the sealing interface device between the first and second plates. In another particular embodiment, said seal comprises at least one protrusion extending in the coupling plane and bearing in a contact zone with the frame-forming portion, said contact zone of the frame-forming portion having a reduced width in the coupling plane relative to the width of the frame-forming portion outside said contact zone.

[0038] The protrusion provides support for the seal in the spacer, facilitating the placement of the sealing interface device between the first and second plates.

[0039] When the seal expands in the coupling plane, the contact area of ​​the frame portion, of reduced width, can deform or even break, preventing the seal from having reduced crushing at the level of the protrusion bearing against the frame portion.

[0040] Preferably, the seal(s) is / are made of a mineral-based material, such as mica, clay or talc.

[0041] Likewise, said spacer is made of a mineral-based material such as mica, clay or talc.

[0042] The sealing interface is thus well suited to achieving a tight coupling at high temperature (between 600°C and 1000°C) while ensuring an electrical insulation function between the first and second plates.

[0043] In practice, the thickness of the sealing gasket(s) is between 0.3 and 1 mm, and preferably between 0.5 and 1 mm before coupling under pressure of said first and second plates.

[0044] In a particular and non-limiting embodiment, the thickness of the sealing gasket(s) is substantially equal to 1 mm and the thickness of said spacer is substantially equal to 0.8 mm before coupling under pressure of said first and second plates.

[0045] In the gas distribution assembly described above, said first plate may be a gas distribution plate and said second plate may be an end plate of a high temperature SOEC / SOFC type solid oxide stack.

[0046] Other features and advantages of the invention will become apparent in the description given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In the attached drawings, given as non-limiting examples: There [ Fig. 1A ] represents, according to a principle diagram in front view, a gas distribution assembly suitable for implementing the present invention; The [ Fig. 1B ] represents, according to a principle diagram in exploded perspective, a gas distribution assembly according to a first embodiment of the invention; The [ Fig. 2] represents, according to a schematic top view, a sealing interface device associated with a first plate of the gas distribution assembly of the figure 1 ; There [ Fig. 3 ] is a schematic top view of the sealing interface device of the figure 2 ; There [ Fig. 4 ] is a perspective view of an enlarged detail of the upper left corner of the figure 2 ; There [ Fig. 5 ] is a diagram illustrating dimension ratios of the sealing interface device of the figure 3 ; THE [ Fig. 6A ] And [ Fig. 6B ] are comparative diagrams of the deformation of a gas distribution assembly according to the prior art and according to an exemplary embodiment of the invention; The [ Fig. 7 ] schematically represents crushing rate curves of a sealing interface according to the prior art and according to an exemplary embodiment of the invention; The [ Fig. 8] is a schematic top view of a sealing interface device according to a second embodiment; The [ Fig. 9 ] is a schematic top view of a sealing interface device according to a third embodiment; The [ Fig. 10 ] is a schematic top view of a sealing interface device according to a fourth embodiment; The [ Fig. 11 ] is a perspective view of an enlarged detail A of the sealing interface device of the figure 10 ; There [ Fig. 12 ] is a schematic top view of a sealing interface device according to a fifth embodiment; The [ Fig. 13 ] is a perspective view of an enlarged detail B of the sealing interface device of the figure 12 ; There [ Fig. 14 ] is a perspective view of an enlarged detail C of the sealing interface device of the figure 12 ; There [ Fig. 15] represents, according to an exploded perspective schematic diagram, a gas distribution assembly according to a second embodiment of the invention; and The [ Fig. 16 ] is a schematic top view of the sealing interface device of the figure 15 .

[0048] Throughout the figures, like references may designate like or similar elements.

[0049] Additionally, the different parts in the figures are not necessarily on a uniform scale to make the figures more readable. DETAILED DESCRIPTION OF THE INVENTION

[0050] We will first describe with reference to the Figures 1A and 1B an example of a gas distribution assembly according to a first embodiment of the invention.

[0051] In this first embodiment, the gas distribution assembly is implemented during a high-temperature sealed coupling of a SOEC / SOFC type solid oxide stack operating at high temperature with a gas distribution plate for the supply and outlet of gases. In the remainder of the description, the gas distribution plate will also be commonly referred to as a collector or manifold.

[0052] This has been illustrated very schematically in the Figure 1A a 10-layer solid oxide stack of the SOEC / SOFC type.

[0053] In a known manner, such a stack 10 comprises several electrochemical cells, each formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, and several intermediate interconnectors each arranged between two adjacent electrochemical cells. This set of electrochemical cells and intermediate interconnectors can also be designated by " stack» in English. The stack 10 comprises an upper end plate 11 and a lower end plate 12, between which the electrochemical cells and the intermediate interconnectors are sandwiched.

[0054] Such a stacking is known, for example in document FR 3 075 481, and does not need to be described in more detail here.

[0055] The stack 10 is intended to be coupled with a gas distribution plate 20 for the supply and outlet of gases in the stack 10 with solid oxides of the SOEC / SOFC type operating at high temperature.

[0056] The gas distribution plate or collector 20 comprises at least one communication orifice for the supply or outlet of gas positioned opposite an end plate of the stack, and here the lower end plate 12.

[0057] In this embodiment, the collector 20 comprises, for example, four collection conduits 25, 26 (two are visible in the Figure 1A ) for the supply and outlet of gas, each collection conduit comprising a communication orifice 21, 22, 23, 24 opening onto the surface 20a of the collector 20 as illustrated in Figure 1B .

[0058] In the embodiment of the Figures 1A and 1B , the collector 20 has a surface 20a of substantially rectangular or square shape, each communication orifice 21, 22, 23, 24 of the collector 20 extending parallel respectively to one of the sides of the surface 20a of the collector 20. Each communication orifice 21, 22, 23, 24 of the collector 20 is intended to be positioned opposite a corresponding communication orifice 121, 122, 123, 124 of the lower end plate 12 of the stack 10 so as to allow fluid coupling between the stack 10 and the collector 20 for the supply and outlet of gas.

[0059] The implementation of this fluid coupling between a first plate formed by the collector 20 and a second plate formed by the lower end plate 12 of the stack 10 requires a clamping device 30 to couple under pressure the collector 20 and the lower end plate 12, parallel to each other.

[0060] As illustrated in the Figure 1A, the clamping device may comprise a support 31 intended to support the collector 20 at its center, and a support rod 31 associated with a force distribution plate 33 in contact with the upper end plate 11 of the stack 10. The pressurization of the collector 20 and the stack 10 is carried out by applying a force at the support rod 32, the stack 10 and the collector 20 being clamped between the force distribution plate 33 and the support 31 of the clamping device 30. Alternatively, a clamping device may comprise threaded clamping rods cooperating with nuts and extending through fixing orifices of the collector 20 and the stack 10. Examples of such a clamping device are described for example in the document FR 3 075 481, and it does not need to be described in more detail here.

[0061] In order to ensure sealing in a coupling plane extending between the manifold 20 and the lower end plate 12, a sealing interface device 40 is provided as seen in Figure 1B .

[0062] In this application implementing a 10 solid oxide stack of the SOEC / SOFC type, the sealing interface device must provide high temperature sealing, i.e. resistant to at least 600°C - 1000°C.

[0063] Such a sealing interface device 40 is illustrated in more detail in Figures 2 and 3 .

[0064] It comprises at least one or more sealing gasket(s) arranged in the coupling plane around each communication orifice 21, 22, 23, 24 of the collector 20.

[0065] In the embodiment illustrated in figures 1 to 3, the sealing interface device 40 comprises four sealing gaskets 41, 42, 43, 44 arranged respectively around each communication orifice 21, 22, 23, 24 of the collector 20.

[0066] By way of illustration, in this embodiment, each communication orifice 21, 22, 23, 24 of the collector 20 is formed of an elongated slot-shaped opening, and each seal 41, 42, 43, 44 has an oblong or rectangular shape adapted to extend to the periphery of each communication orifice 21, 22, 23, 24 of the collector 20.

[0067] Each seal 41, 42, 43, 44 is for example a flat seal. Such a seal 41, 42, 43, 44 is produced in the form of a plate, by compacting / rolling a powder of mineral material.

[0068] Each seal 41, 42, 43, 44 is made of a material having electrical insulating properties compatible with the operational constraints of high-temperature electrolyzers or solid oxide fuel cells.

[0069] Each seal 41, 42, 43, 44 can thus be made of a mineral-based material of the mica, clay or talc type. Typically, the seals 41, 42, 43, 44 can be made of mica.

[0070] The thickness of the seals 41, 42, 43, 44 is between 0.3 and 1 mm, and preferably between 0.5 and 1 mm. These ranges of thickness values ​​are well suited for mineral-based materials such as mica or talc, for example, which can be used in high-temperature electrolysis applications. Below 0.5 mm, there is a risk of not compressing the seals sufficiently, for example due to flatness defects in the surface 20a of the collector or the lower end plate 12 of the stack 10, and therefore of not obtaining the required seal.

[0071] Coming back to the figure 2 , the thickness of the seals 41, 42, 43, 44 is measured in a direction z perpendicular to the plane (x,y) in which the surface 20a of the collector 20 extends.

[0072] This is also the thickness of the sealing gaskets 41, 42, 43, 44 before application of the compressive stress.

[0073] The thickness of the sealing gaskets 41, 42, 43, 44 is thus given before the tight mounting of the collector 20 and the stack 10, that is to say before the coupling under pressure of the surface 20a of the collector 20 and the lower end plate 12 of the stack 10.

[0074] Vermiculite-type compressive seals require high compression to achieve sufficient sealing when coupling the collector 20 and the stack 10. A compressive stress equal to a few MPa or several tens of MPa is necessary to achieve compression ratios of the seal to ensure sealing.

[0075] In order to limit the deformations induced by these high compressive stresses, in particular at the surface 20a of the collector 20 and the lower end plate 12 of the stack 10, the sealing interface device 40 comprises a spacer 50 intended to be arranged in the coupling plane extending between the collector 20 and the lower end plate 12 of the stack 10.

[0076] The thickness of the sealing gaskets 41, 42, 43, 44 before coupling under pressure is strictly greater than the thickness of the spacer 50.

[0077] Thus, the spacer 50 has a thickness less than the thickness of the seals 41, 42, 43, 44, which allows, when tightening the stack 10 on the collector 20, to first compress the seals 41, 42, 43, 44. This start of compression will cause the seals 41, 42, 43, 44 to be crushed until the lower end plate 12 of the stack 10 comes into abutment against both the seals 41, 42, 43, 44 and the spacer 50. The spacer thus has a crushing limiter function, limiting the movement of the lower end plate 12 crushing the seals 41, 42, 43, 44.

[0078] Furthermore, as illustrated in the figure 3 , the spacer 50 and the sealing gaskets 41, 42, 43, 44 form a sealing interface having two planes of symmetry perpendicular to each other and perpendicular to the coupling plane defined by the plane ((x,y)) on the figure 3 .

[0079] In this exemplary embodiment, the sealing interface device 40 has a plane of symmetry (x,z) and a plane of symmetry (y,z), both perpendicular to the coupling plane ((x,y)) in which the sealing is carried out.

[0080] Thus, the spacer 50 makes it possible to limit the crushing of the sealing joints 41, 42, 43, 44 and the movement of the lower end plate 12 symmetrically in the coupling plane ((x, y)).

[0081] The spacer 50 thus makes it possible to reduce, symmetrically in the coupling plane, the bending moment applied to the plates bearing on the sealing joints 41, 42, 43, 44. The stresses and deformations applied to the collector 20 and the stack 10, and in particular the lower end plate 12 are reduced.

[0082] The risks of bending of the lower 12 and upper 11 end plates of the stack 10 and of the collector 20 are reduced, in order to guarantee the best possible sealing during mechanical compression of the stack and of the various elements of the sealing interface device 40.

[0083] The choice of the thickness of the seals 41, 42, 43, 44 and the spacer 20 is determined so that the difference in thickness between the seals 41, 42, 43, 44 and the spacer 50 is a few tenths, and for example between 1 and 3 tenths when the seals have thicknesses of the order of a millimeter.

[0084] Thus, by way of non-limiting example, when the sealing gaskets 41, 42, 43, 44 have a thickness substantially equal to 1 mm, the thickness of the spacer 50 is substantially equal to 0.8 mm before coupling under pressure of the collector 20 and the stack 10.

[0085] A thickness difference of 0.2 mm between the seals 41, 42, 43, 44 and the spacer 50 makes it possible to guarantee that the crushing rate of the seals 41, 42, 43, 44 is of the order of 20% and in any event does not exceed 25%.

[0086] Of course, the thickness values ​​and the thickness differences between the spacer 50 and the seals 41, 42, 43, 44 can be chosen according to the maximum crushing rate desired for the seals 41, 42, 43, 44.

[0087] Typically, for a flat seal, a maximum crushing rate of between 10 and 25% of its initial dimension is preferred, before coupling under pressure.

[0088] It is thus possible to control the crushing rate of the sealing gaskets 41, 42, 43, 44 and to avoid their rupture, which could harm the seal.

[0089] Preferably, in applications implementing a solid oxide stack 10 of the SOEC / SOFC type, the spacer 50 is also made of a mineral-based material, such as mica, clay or talc.

[0090] The sealing interface device 40 thus makes it possible to provide a sealing interface well suited to high temperature and providing adequate electrical insulation.

[0091] The material of the spacer 50 may be similar or identical to that of the seals 41, 42, 43, 44.

[0092] Among the available materials that can be used for the tight coupling of a SOEC / SOFC type solid oxide stack operating at high temperature, there are different grades of vermiculite, obtained by different implementations of the same material. The grades of vermiculite have stiffnesses with values ​​that can vary according to a ratio of 1 to 10.

[0093] It is recalled that the stiffness (in Newtons per meter or N / m) of a body characterizes the resistance to elastic deformation of this body. The higher the stiffness, the greater the force to be applied to obtain a given deflection of this body or the less the deflection of this body will be for a given force.

[0094] Thus, for the same compressive stress, the crushing rate of one grade of vermiculite could be ten times greater than for another grade of vermiculite.

[0095] The measurement of the stiffness of these mineral materials and their comparison can be implemented by compression test methods, as specified by ISO 17892-7:2017, which defines a method for determining uniaxial compressive strength.

[0096] Preferably, the stiffness of the material constituting the spacer 50 may be greater than the stiffness of the material constituting the sealing joints 41, 42, 43, 44.

[0097] The stiffness of the material constituting the spacer 50 thus makes it possible to increase the crushing limiter function during the coupling under pressure of the stack 10 and the collector 20. A spacer 50 with a stiffness greater than that of the sealing joints 41, 42, 43, 44 provides rigid mechanical support at the level of the sealing interface device 40, which blocks the relative movement of the collector 20 and the lower end plate 12 of the stack 10, limiting de facto the compression of the sealing gaskets 41, 42, 43, 44 and providing support to reduce the bending moment of the facing plates in the coupling plane (x,y).

[0098] Thus it is possible to crush the sealing gaskets 41, 42, 43, 44 in a precise range of deformation, depending on the compression force applied for tightening the gas distribution assembly.

[0099] Similarly, the area of ​​the surface formed by the spacer 50 in the coupling plane may be greater than the area of ​​the surface formed by the seals 41, 42, 43, 44 in this coupling plane (x,y).

[0100] The area formed in the coupling plane, corresponding to the (x,y) plane at the figure 3 , corresponds both for the spacer 50 and for the sealing joints 41, 42, 43, 44 to the cumulative surface in the plane (x,y) of the surfaces of the different portions of spacer 50 or sealing joints 41, 42, 43, 44.

[0101] A large surface area formed by the spacer 50, compared to that formed by the seals 41, 42, 43, 44, in the coupling plane (x,y), makes it possible to guarantee, even under a compressive stress largely higher than the required value (for example a few MPa) that the seals 41, 42, 43, 44 are crushed to a desired crushing rate, without risk of over-crushing.

[0102] If the materials of the spacer 50 and the seals 41, 42, 43, 44 are identical and have the same stiffness, a larger surface area for the spacer 50 than for the seals 41, 42, 43, 44 in the coupling plane (x,y) allows the spacer 50 to provide a crushing limiter function for the seals 41, 42, 43, 44.

[0103] If, in addition, the material of the spacer 50 has a stiffness greater than that of the material constituting the seals 41, 42, 43, 44, the crushing limiter function of the seals 41, 42, 43, 44 provided by the spacer is further improved.

[0104] In the embodiment illustrated in figures 1 to 3 , the spacer 50 is formed from a single-piece flat structure comprising frame-forming portions 51, 52, 53, 54 extending respectively to the periphery of the sealing joints 41, 42, 43, 44.

[0105] The one-piece planar structure may be formed from a one-piece plate comprising the frame portions 51, 52, 53, 54 or as illustrated in figure 3 , of a plate further comprising openings 50'. The openings 50' make it possible to limit the support surface formed by the spacer 50 in the coupling plane (x,y) while providing good rigidity to the sealing interface device 40.

[0106] In a non-limiting manner, these 50' openings are here 4 in number, and arranged according to a 90° distribution in the coupling plane (x,y).

[0107] The shape of the openings 50' can be variable and adapted according to the geometry of the different parts of the gas distribution assembly. Preferably, the openings 50' make it possible to maintain a surface area formed by the spacer 50 greater than the surface area formed by the sealing joints 41, 42, 43, 44.

[0108] The shape of the openings 50' can also make it possible to keep a central support portion 55 in the center of the single-piece flat structure of the spacer 50.

[0109] Here, and in a non-limiting manner, the central support portion 55 has the shape of a cross.

[0110] The central support portion 55 is arranged equidistant from the seals 41, 42, 43, 44 in the sealing interface device 40. It makes it possible to further limit the bending moment created in the lower end plate 12 of the stack 10 and in the collector 20 during coupling under pressure.

[0111] Such a central support portion 55 in the spacer 50 is all the more useful since the sealing joints 41, 42, 43, 44 associated with the communication orifices 21, 22, 23, 34 are placed at the periphery of the collector 20.

[0112] The larger the surface area 20a of the collector 20, the greater the risk of deformation. Similarly, the greater the distance between the seals 41, 42, 43, 44, the greater the risk of bending and deformation.

[0113] The one-piece planar structure of the spacer 50 as illustrated in the figure 3further comprises orifices 56, here two in number, allowing the insertion of positioning pins (not illustrated). These positioning pins are mounted in counterbores made in the surface 20a of the manifold 20, and are adapted to be inserted into the orifices 56 of the spacer 50 and into the lower end plate 12 of the stack 10 to guarantee precise centering and relative positioning of the stack 10, the sealing interface device 40 and the manifold 20 before their coupling under pressure.

[0114] The frame-forming portions 51, 52, 53, 54 make it possible to enclose each sealing joint 41, 42, 43, 44 and to provide additional sealing around each communication orifice 21, 22, 23, 24 of the collector 20.

[0115] It has been illustrated to the Figures 4 and 5in more detail the mounting of a seal J1 in a frame portion C2. The seal J1 can be any seal 41, 42, 43, 44 and the frame portion C2 corresponds to a frame portion 51, 52, 53, 53 extending at the periphery of a seal 41, 42, 43, 44.

[0116] Generally, the dimensions of the opening formed by a frame-forming portion C2 extending at the periphery of a seal J1 in the coupling plane (x,y) are strictly greater than the dimensions of the seal J1 in this coupling plane (x,y).

[0117] As described above, the frame portion C2 has a thickness E2 less than the thickness E1 of the seal J1, which allows, when applying a compressive force, to compress the seal J1 first.

[0118] In terms of geometry, the width L1 of the sealing gasket J1 must be smaller than the width L2 of the opening formed in the frame portion C2.

[0119] Similarly, the length of the sealing gasket J1 must be shorter than the length of the opening formed in the frame portion C2.

[0120] Thus, there is a clearance between the seal J1 and the frame portion C2, allowing free radial expansion, in the coupling plane (x,y), of the seal J1 when it is crushed.

[0121] Preferably, the clearance exists all around the seal J1, between the seal J1 and the frame portion C2.

[0122] The sealing function of the seal J1 can thus be ensured as long as the spacer does not hinder the achievement of a minimum crushing rate of the seal J1. The thickness E1 of the seal J1 being strictly greater than the thickness E2 of the frame-forming portion C2, if the applied compressive force is sufficient, the crushing rate of the seal J1 will be directly linked to the difference in thicknesses E1 and E2.

[0123] The sealing gasket J1 will be able to be freely crushed and deformed in the opening formed by the frame portion C2, until the sealing gasket J1 comes into abutment against the frame portion C2 of the spacer.

[0124] We have illustrated schematically in the Figures 6A , 6B and 7 the comparative behavior of a gas distribution assembly as described previously, with or without spacer 50 in the sealing interface device 40.

[0125] Thus, when a compression force F is applied for the tightening coupling of the stack 10 on the collector 20, the presence of the spacer (situation of the Figure 6B ) allows in comparison with the sealing interface without spacer (situation of the Figure 6A ), to limit the bending and buckling of the various parts, and in particular of the lower end plate 12 of the stack 10.

[0126] Indeed, a compressive and clamping force of the stack 10 on the collector 20, at several MPa and at high temperature in this configuration, can lead to a bending load on the end plates of the stack 10 or on the collector 20, likely to deform the stack 10 positioned on the collector 20.

[0127] The behavior of the sealing interface device 40 with and without spacer 50 is also illustrated in figure 7, schematically representing the crushing rate curves (in % crushing) as a function of the force applied (in Newton) on the sealing joints J1 alone or coupled with a spacer comprising a portion forming a frame C2 around each sealing joint J1.

[0128] We can thus see that the crushing ratio of the J1 seals alone can reach 25% for example, for a compression force of 5000 N.

[0129] Conversely, when the J1 seals are associated with a spacer comprising a frame-forming portion C2 around each J1 seal, the crushing rate is similar to that of the J1 seals alone at the start of compression, with a compression force not exceeding approximately 2000 N. Then, the crushing rate of the J1 seals is reduced from approximately 25% to 12% for a compression force of between 2000 and 5000 N.

[0130] As visible at the figure 7 , the crushing of the sealing gaskets J1 coupled to the spacer comprising a frame-forming portion C2 then follows the same crushing slope as the spacer comprising a frame-forming portion C2 alone.

[0131] The spacer 50 thus makes it possible to control the crushing rate of the sealing joints 41, 42, 43, 44 in the sealing interface device 40 and to reduce the bending stresses in the stack 10, in particular when the spacer 50 takes up the compression forces at the center of the coupling plane (x,y).

[0132] It is thus advantageous to have a spacer 50 formed from a single-piece flat structure because the maximum crushing ratio of the sealing joints 41, 42, 43, 44 can be controlled by varying the surface area and / or the stiffness of the spacer 50.

[0133] The thickness of the spacer 50 being less than the thickness of the seals 41, 42, 43, 44, it is possible to crush the seals 41, 42, 43, 44 to a given value, sufficient to guarantee sealing in the coupling plane, and without being disturbed by the presence of the spacer 50.

[0134] By way of non-limiting example, it is possible to use a spacer 50 which has a surface area identical to the cumulative surface area of ​​the sealing joints 41, 42, 43, 44 and formed from a material, such as vermiculite, with a stiffness 4 times greater than the stiffness of the material of the sealing joints 41, 42, 43, 44.

[0135] Alternatively, the same material can also be selected for the spacer 50 and the seals 41, 42, 43, 44. The only difference between the spacer 50 and the seals 41, 42, 43, 44 then lies in the thickness E1 of the seals 41, 42, 43, 44 and the thickness E2 of the spacer 50. The spacer 50 can be dimensioned such that E2 = 0.9 x E1.

[0136] Of course, the invention is not limited to the embodiments described above.

[0137] In particular, the spacer 50 described above is formed from a single-piece planar structure, which makes it easier to position the sealing interface device 40 in the coupling plane (x,y).

[0138] However, in the embodiment described with reference to the figures 1 to 3, defects in the flatness of the surface 20a of the collector 20 or of the lower end plate 12 of the stack 10 can locally lead to point supports in the coupling plane (x,y), limiting the crushing rate of the seals 41, 42, 43, 44. This effect can in particular be amplified if the seals 41, 42, 43, 44 are distant from each other.

[0139] To overcome this drawback, the spacer of the sealing interface device can be formed in several pieces.

[0140] As illustrated in the figure 8 , the spacer 150 comprises for example several frame-forming portions 151, 152, 153, 154 arranged respectively at the periphery of the sealing joints 41, 42, 43, 44.

[0141] In this embodiment, each frame portion 151, 152, 153, 154 comprises a rectangular frame portion adapted to surround each seal 41, 42, 43, 44 and tabs 151', 152', 153', 154' allowing the frame portions 151, 152, 153, 154 to be manipulated, in particular for their mounting around the seals 41, 42, 43, 44 on the surface 20a of the collector 20.

[0142] In this embodiment, the spacer 150 further comprises a central support portion 155 arranged equidistant from the sealing joints 41, 42, 43, 44.

[0143] The central support portion 155 is arranged in the center of the surface 20a of the collector 20 and is formed of a four-armed cross arranged in the coupling plane x, y.

[0144] The central support portion 155 as illustrated in the figure 8further comprises orifices 156, here two in number, allowing the insertion of positioning pins (not illustrated). These positioning pins are mounted in counterbores made in the surface 20a of the collector 20, and are adapted to be inserted into the orifices 156 of the central support portion 155 of the spacer 150 and in the lower end plate 12 of the stack 10 to guarantee precise centering and relative positioning of the stack 10, the central support portion 155 and the collector 20 for coupling under pressure.

[0145] The central support portion 155 makes it possible to limit the bending moment created in the lower end plate 12 of the stack 10 and in the collector 20 during coupling under pressure.

[0146] To the figure 8, the spacer 150 is thus made up of the four frame-forming portions 151, 152, 153, 154 and the central support portion 155. It has characteristics similar to those described previously in relation to the figures 1 to 5 in terms of usable material, stiffness and surface area in the coupling plane (x,y) as a function of the characteristics of the seals 41, 42, 43, 44.

[0147] The thickness E2 of the frame-forming portions 151, 152, 153, 154 and of the central support portion 155 is identical and the thickness E2 of the different parts forming the spacer 150 is strictly less than the thickness E1 of the sealing joints 41, 42, 43, 44.

[0148] In this embodiment, the frame portions 151, 152, 153, 154 and the central support portion 155 make it possible to limit the bending moment applied to the stack 10 and to the collector 20.

[0149] Furthermore, when the frame-forming portions 151, 152, 153, 154 are formed from frames having a small cross-section, and for example substantially equal or similar to that of the seals 41, 42, 43, 44, the frame-forming portions 151, 152, 153, 154 can be subjected to compressive stresses allowing them to be compressed sufficiently to ensure a second sealing barrier, complementary to that formed by each seal 41, 42, 43, 44 around each communication orifice 21, 22, 23, 24 of the collector 20.

[0150] In another embodiment illustrated in figure 9 , when the sealing interface device 40 comprises several seals 41, 42, 43, 44, the spacer may comprise only a support portion 250 arranged equidistant from the sealing seals 41, 42, 43, 44.

[0151] In the embodiment illustrated in the figure 9, the support portion 250 forms a support wedge arranged in the center of the coupling plane (x,y) of the collector 20 and the stack 10. By way of non-limiting example, the support portion 250 may be in the form of a washer 250. The spacer thus formed from a support portion 250 in the form of a washer has characteristics similar to those described previously in relation to the figures 1 to 5 in terms of usable material, stiffness and surface area in the coupling plane (x,y) as a function of the characteristics of the seals 41, 42, 43, 44.

[0152] The thickness E2 of the washer-shaped support portion 250 is strictly less than the thickness E1 of the sealing gaskets 41, 42, 43, 44.

[0153] The washer-shaped support portion 250 thus provides a crushing limiter function, limiting, once the support is established on the washer, the movement of the lower end plate 12 of the stack in the direction of the surface 20a of the collector 20. The support portion 250 being equidistant from the seals 41, 42, 43, 44, the distance between each support point in the coupling plane, between the support portion 250 and the seals 41, 42, 43, 44, is as small as possible. The bending moment created in the lower end plate 12 of the stack 10 is thus all the more reduced.

[0154] Of course, the washer shape for the bearing portion 250 is illustrative and could be replaced by a disc or quadrilateral shape.

[0155] We will now describe with reference to the figures 10 to 14examples of advantageous mounting of the sealing joints 41, 42, 43, 44 in a spacer 350, 450 formed from a single-piece flat structure as described previously with reference to figures 1 to 5 .

[0156] The 350, 450 spacers illustrated in figures 10 to 14 are similar to that described with reference to figures 1 to 5 and have substantially the same shapes and characteristics as those described previously in relation to the figures 1 to 5 .

[0157] A spacer 350, 450 having a one-piece planar structure makes it easier to position the sealing interface device 40 in the coupling plane (x,y). By further mounting the seals 41, 42, 43, 44 in the spacer 350, 450, the operation of installing the seals 41, 42, 43, 44 around each orifice 21, 22, 23, 24 can be simplified.

[0158] As illustrated in Figures 10 and 11, the spacer 350 comprises frame-forming portions 351, 352, 353, 354 around each seal 41, 42, 43, 44.

[0159] Cutouts of the spacer 350 at the frame portions 351, 352, 353, 354 are provided to create one or more projecting fingers 360.

[0160] Thus, each frame-forming portion 351, 352, 353, 354 is provided with one or more projecting fingers 360 extending towards a seal 41, 42, 43, 44 and in contact with this seal 41, 42, 43, 44.

[0161] In the embodiment illustrated in Figures 10 and 11 , each frame-forming portion 351, 352, 353, 354 comprises four fingers 360, distributed in pairs on each side of a seal 41, 42, 43, 44 along its length and arranged face to face in pairs. The fingers 360 thus form four supports or holding pins, holding the seal 41, 42, 43, 44 inside the frame-forming portion 351, 352, 353, 354.

[0162] The fingers 360 preferably provide point support for the seals 41, 42, 43, 44 and facilitate the positioning of the spacer 350 and the seals 41, 42, 43, 44 on the surface 20a of the collector 20.

[0163] In addition, a point of glue or adhesive can be added at the level of the point support zone, in addition to the simple mechanical support formed by the fingers 360 against the sealing joints 41, 42, 43, 44.

[0164] In another embodiment, the holding elements may be formed on the side of the seals 41, 42, 43, 44.

[0165] As illustrated in figures 12, 13 And 14 , the spacer 450 comprises frame-forming portions 451, 452, 453, 454 around each seal 41, 42, 43, 44.

[0166] Each seal 41, 42, 43, 44 comprises at least one protrusion 460 extending in the coupling plane (x,y) and bearing in a contact zone with the frame-forming portion 451, 452, 453, 454 which surrounds it.

[0167] In the embodiment illustrated in figures 12 to 14 , each seal 41, 42, 43, 44 comprises eight protrusions 460 arranged symmetrically around the seal 41, 42, 43, 44.

[0168] In this embodiment, and by way of non-limiting example, each seal 41, 42, 43, 44 comprises six protrusions 460 distributed in pairs on each side of a seal 41, 42, 43, 44, along its length, and arranged face to face in pairs, and two protrusions 460 arranged at the ends of the seal 41, 42, 43, 44.

[0169] Of course, the number of protrusions 460 around the seals 41, 42, 43, 44 and their distribution are only examples and may vary depending on the shape and dimensions of the seals 41, 42, 43, 44.

[0170] The protrusions 460 are adapted to form supports for holding each seal 41, 42, 43, 44 in the frame-forming portion 451, 452, 453, 454 which surrounds it. To ensure expansion of the seal 41, 42, 43, 44 during its crushing at the time of coupling under pressure of the stack 10 and the collector 20, the frame-forming portions 451, 452, 453, 454 are machined so that the latter do not oppose the expansion of the seal 41, 42, 43, 44 and locally induce under-crushing of the seal 41, 42, 43, 44.

[0171] In practice, the contact area of ​​the frame-forming portion 451, 452, 453, 454 with a protrusion 460 has a reduced width in the coupling plane (x,y) compared to the width of the frame-forming portion 451, 452, 453, 454 outside the contact area. One way of proceeding is to create, opposite each protrusion 460, a weakening zone in the form of machining of the frame-forming portion 451, 452, 453, 454, leaving a free space behind a strip of reduced width of the frame-forming portion 451, 452, 453, 454.

[0172] In the embodiment illustrated in figures 12 to 14 , each frame-forming portion 451, 452, 453, 454 comprises recesses 470 machined opposite each contact zone of the frame-forming portion 451, 452, 453, 454 with a protrusion 460 of the sealing gasket 41, 42, 43, 44.

[0173] The compression of the seal 41, 42, 43, 44 and its expansion create a radial force in the coupling plane (x,y), generating stresses in the contact zone, which is thus capable of deforming or even breaking. The free space located at the contact zone thanks to the recess 470 allows the reduced width strip of the frame-forming portion 451, 452, 453, 454 to be moved apart during its deformation or after its rupture, without generating a local excess thickness at the seal 41, 42, 43, 44.

[0174] More generally, the invention as described above can be implemented for any type of geometry of flat sealing gasket inserted between two parallel flanges. The shape of the sealing interface device can be very variable, depending on the shape of the plates implemented in the coupling plane.

[0175] It has been illustrated to the figures 15 And 16an example of implementation for standard flanges of the PN6 flange type.

[0176] In high temperature electrolysis (HTE) applications, this type of flanges 510, 520 is equipped with a flat sealing gasket 541, for example made of vermiculite.

[0177] Each flange 510, 520 comprises an end plate 510a, 520a into which a communication orifice opens for the supply or outlet of gas. The end plates 510a, 520a are parallel to each other and define between them a coupling plane during coupling under pressure by a clamping device (not shown) of the two flanges 510, 520.

[0178] The flat seal 541 is thus arranged in this coupling plane around a communication orifice 521 of an end plate 510a of a first flange 510.

[0179] In this embodiment, the communication orifice 521 is circular and the flat sealing gasket 541 is formed of a washer.

[0180] The sealing interface device 540 comprises, in addition to the flat sealing gasket 541, a spacer 550 arranged in the coupling plane between the two end plates 510a, 520a of the flanges 510, 520.

[0181] As visible at the figure 16 , the spacer 550 and the flat sealing gasket 541 form a sealing interface having two planes of symmetry perpendicular to each other and perpendicular to the coupling plane.

[0182] As described previously for the other embodiments, the thickness of the sealing gasket 541 before coupling under pressure of the two flanges 510, 520 is strictly greater than the thickness of the spacer 550.

[0183] In the embodiment illustrated in figures 15 And 16, the spacer 550 is formed as a washer around the flat seal 541, thereby forming a frame portion extending around the periphery of the flat seal 541.

[0184] The spacer 550 thus formed in the form of a washer has characteristics similar to those described previously in relation to the figures 1 to 5 in terms of usable material, stiffness and surface area in the coupling plane (x,y) as a function of the characteristics of the flat seal 541.

[0185] In this embodiment, the washer-shaped spacer 550 has a function of limiting the crushing of the flat sealing gasket 541.

[0186] It avoids having to control the tightening torque when mounting the flanges 510, 520 under pressure. The spacer 550 prevents the flat sealing gasket 541 from being too flat, which would impair the sealing of the mounting of the flanges 510, 520.

[0187] As previously described in connection with the figures 10 to 14 , the spacer 550 may comprise means for holding the flat seal 541 in position inside the frame formed by the washer-shaped spacer, which facilitates its assembly and positioning between the two flanges 510, 520, in particular when the coupling plane between the two end plates 510a, 520a of the two flanges is in a vertical plane. The centering of the flat seal 541 is thus facilitated.

[0188] In the embodiment illustrated in figures 15 And 16 , the flat sealing gasket 541 comprises protrusions 560 extending in the coupling plane and bearing in a contact zone with the frame-forming portion of the spacer 550 which surrounds it.

[0189] For example, the flat seal 541 comprises four protrusions 560 arranged symmetrically around the flat seal 541, and for example along two perpendicular diameters of the flat seal 541 in the form of a washer.

[0190] Of course, the number of protrusions 560 around the seal 541 and their distribution may vary depending on the shape and dimensions of the flat seal 541.

[0191] As described in connection with the figures 12 to 14, the protrusions 560 are adapted to form supports for holding the seal 541, 42, 43, 44 in the spacer 550. To ensure expansion of the flat seal 541 during its crushing at the time of coupling under pressure of the two flanges 510, 520, the spacer 550 comprises recesses 570 machined opposite each contact zone of the spacer 550 with a protrusion 560 of the flat seal 541. The characteristics and advantages of this holding configuration are similar to those described in relation to the figures 12 to 14. Alternatively, the means for holding the flat seal 541 in position inside the frame formed by the washer-shaped spacer 550 may be formed by projecting fingers (not shown) on the spacer 550, extending towards the flat seal 541 and in contact with the flat seal 541. Such a holding configuration has characteristics and advantages similar to those described in relation to the embodiment of the Figures 10 and 11 .

[0192] Thanks to these holding means, the positioning and centering of the flat seal 541, coupled to the spacer 550, are facilitated in the coupling plane. The spacer 550 also ensures good electrical insulation and provides a second sealing barrier around the flat seal 541.

[0193] Of course, the present invention is not limited to the exemplary embodiments given above.

[0194] In particular, the sealing interface device can be applicable to all high temperature and low pressure applications. It can equip any type of gas distribution assembly implementing different geometry of flat gaskets inserted between two parallel flanges or plates.

Claims

1. Gas-distribution assembly comprising: - a first plate (20; 510a) and a second plate (12; 520a), the first plate (20; 510a) comprising at least one communication port (21, 22, 23, 24; 521) for the gas inlet or outlet positioned opposite a corresponding communication port (121, 122, 123, 124) of the second plate (12), said first and second plates extending parallel to one another; - a clamping device (30) for compressively coupling said first and second plates (20, 12) in a coupling plane ((x,y)) parallel to said first and second plates; and - a sealing interface device (40; 540) comprising at least one seal (41, 42, 43, 44; 541) disposed in said coupling plane ((x,y)) around said at least one communication port (21, 22, 23, 24; 521) of said first plate (20; 510a), characterised in that the sealing interface device (40; 540) comprises a spacer (50; 150; 250; 350; 450; 550) disposed in said coupling plane ((x,y)) between the first and second plates (20, 12; 510a , 520a), said spacer (50; 150; 250; 350; 450; 550) and the seal(s) (41, 42, 43, 44; 541) forming a sealing interface having two planes of symmetry ((x,z), (y,z)) perpendicular to each other and perpendicular to said coupling plane ((x,y)), the thickness of the seal(s) (41, 42, 43, 44; 541) before pressure coupling of said first and second plates (20, 12; 510a, 520a) being strictly greater than the thickness of said spacer (50; 150; 250; 350; 450; 550).

2. Gas-distribution assembly according to claim 1, characterised in that the area of the surface formed by the spacer (50; 150; 250; 350; 450; 550) in said coupling plane ((x,y)) is greater than the area of the surface formed by the seal(s) (41, 42, 43, 44; 541) in said coupling plane ((x,y)).

3. Gas-distribution assembly according to one of claims 1 or 2, characterised in that the stiffness of the material constituting the spacer (50; 150; 250; 350; 450; 550) is greater than the stiffness of the material constituting the seal(s) (41, 42, 43, 44; 541).

4. Gas-distribution assembly according to one of claims 1 to 3, characterised in that said spacer (50; 150; 350; 450; 550) comprises at least one frame-forming portion (51, 52, 53, 54; 151, 152, 153, 154; 351, 352, 353, 354; 451, 452, 453, 453; 550) extending to the periphery of a seal (41, 42, 43, 44; 541).

5. Gas-distribution assembly according to one of claims 1 to 4, characterised in that the sealing interface device (40) comprises several seals (41, 42, 43, 44), said spacer (50; 150; 250) comprising a bearing portion (55; 155; 250) arranged equidistantly from said seals (41, 42, 43, 44).

6. Gas-distribution assembly according to claim 5, characterised in that said spacer (50; 150; 350; 450) comprises several frame-forming portions (51, 52, 53, 54; 151, 152, 153, 154; 351, 352, 353, 354; 451, 452, 453, 454) extending to the periphery respectively of said plurality of seals (41, 42, 43, 44).

7. Gas-distribution assembly according to claim 6, characterised in that said spacer (50; 350; 450) is formed of a one-piece flat structure comprising said frame-forming portions (51, 52, 53, 54; 351, 352, 353, 354; 451, 452, 453, 454).

8. Gas-distribution assembly according to one of claims 4 to 7, characterised in that the dimensions of an opening formed by each frame-forming portion (51, 52, 53, 54; 151, 152, 153, 154; 351, 352, 353, 354; 451, 452, 453, 454; 550) extending to the periphery of a seal (41, 42, 43, 44; 541) in the coupling plane ((x,y)) are strictly greater than the dimensions of said seal (41, 42, 43, 44; 541) in said coupling plane ((x,y)).

9. Gas-distribution assembly according to claim 8, characterised in that each frame-forming portion (351, 352, 353, 354) is provided with one or more protruding fingers (360) extending toward said seal (41, 42, 43, 44) and in contact with said seal (41, 42, 43, 44).

10. Gas-distribution assembly according to one of claims 8 or 9, characterised in that said seal (41, 42, 43, 44; 541) includes at least one bulge (460; 560) extending in the coupling plane ((x,y)) and bearing in a contact area with the frame portion (451, 452, 453, 454; 550), said contact area of the frame-forming portion (451, 452, 453, 454; 550) having a reduced width in the coupling plane ((x,y)) relative to the width of the frame-forming portion (451, 452, 453, 454; 550) outside said contact area.

11. Gas-distribution assembly according to any one of claims 1 to 10, characterised in that the seal(s) (41, 42, 43, 44; 541) is / are made of a mineral-based material such as mica, clay or talc.

12. Gas-distribution assembly according to one of claims 1 to 11, characterised in that said spacer (50; 150; 250; 350; 450; 550) is made of a mineral-based material, such as mica, clay or talc.

13. Gas-distribution assembly according to one of claims 1 to 12, characterised in that the thickness of the seal(s) (41, 42, 43, 44; 541) is between 0.3 and 1 mm, and preferably between 0.5 and 1 mm, before pressure coupling of said first and second plates (20, 12; 510a, 520a).

14. Gas-distribution assembly according to claim 13, characterised in that the thickness of the seal(s) (41, 42, 44, 45; 541) is substantially equal to 1 mm and the thickness of said spacer (50; 150; 250; 350; 450; 550) is substantially equal to 0.8 mm before pressure coupling of said first and second plates (20, 12; 510a, 520a).

15. Gas-distribution assembly according to one of claims 1 to 14, characterised in that said first plate (20) is a gas-distribution plate and said second plate (12) is an end plate of a SOEC / SOFC-type solid oxide stack (10) operating at high temperature.