SOEC / SOFC solid oxide cell stack and assembly including outer guide element

Abstract

The main subject of the invention is an assembly (80) comprising a stack (20) of SOEC / SOFC solid oxide cells, said stack consisting of a number of plates (P) stacked one on top of the other, each plate (P) having an outer side (S1), said number of plates (P) including at least a number of electrochemical cells, a number of interconnects and an upper end plate (42) and a lower end plate (41), and at least two guiding elements (11, 12, 13, 14) ensuring that the vertical stacking of at least some of the plates (P) of the stack (20) is guided, Said at least two guide elements (11, 12, 13, 14) are characterised in that they extend perpendicularly in a vertical direction (Z) and bear against an outer side surface (Sl) of each of said at least some plates (P).

Description

[Technical field]

[0001] The present invention relates to the general field of high-temperature electrolysis (HTE), in particular high-temperature steam electrolysis (HTSE), carbon dioxide (CO2) electrolysis or high-temperature co-electrolysis of water steam and carbon dioxide (CO2), known by the English names "High-Temperature Electrolysis" (HTE) and "High-Temperature Steam Electrolysis" (HTSE), respectively.

[0002] More particularly, the invention relates to the field of high-temperature solid oxide electrolysis devices, commonly referred to by the acronym SOEC, which stands for "Solid-Oxide Electrolysis Cell" in English.

[0003] This also relates to the field of high-temperature solid oxide fuel cells, usually referred to by the acronym SOFC, which stands for "Solid-Oxide Fuel Cells" in English.

[0004] More generally, the invention therefore relates to the field of solid oxide stacks of the SOEC / SOFC type operating at high temperatures.

[0005] More particularly, the present invention relates to an assembly including a SOEC / SOFC type solid oxide cell stack and an outer guide element, and to an associated conditioning process. [Background technology]

[0006] In the context of a SOEC-type high-temperature solid oxide electrolyzer, water vapor (H2O) is converted to dihydrogen (H2) and dioxygen (O2) and / or carbon dioxide (CO2) is converted to carbon monoxide (CO) and dioxygen (O2) by an electric current in the same electrochemical device. In the context of a SOFC-type high-temperature solid oxide fuel cell, the operation is reversed to generate electric current and heat by feeding dihydrogen (H2) or other fuels such as methane (CH4), natural gas, biogas, and dioxygen (O2), usually air. For simplicity, the following description gives priority to the operation of a SOEC-type high-temperature solid oxide electrolyzer performing electrolysis of water vapor. Nevertheless, this operation is applicable to the electrolysis of carbon dioxide (CO2) or to the co-electrolysis of water vapor and carbon dioxide (CO2) at high temperatures. In addition, this operation can be transposed to the case of a SOFC-type high-temperature solid oxide fuel cell.

[0007] To perform water electrolysis, it is advantageous to do this at high temperatures, usually between 600 and 1000 °C, because it is more advantageous to electrolyze water vapor than liquid water, and because part of the energy required for the reaction can be provided by heat, which is cheaper than electricity.

[0008] To perform high-temperature steam electrolysis (HTSE), the SOEC-type high-temperature solid oxide electrolyzer consists of a stack of basic units, each of which contains a solid oxide electrolysis cell, or electrochemical cell, consisting of three anode / electrolyte / cathode layers stacked on top of each other, and an interconnect plate, also called a bipolar plate or interconnector, made of a metal alloy. Each electrochemical cell is sandwiched between two interconnect plates. The SOEC-type high-temperature solid oxide electrolyzer is then an alternating stack of electrochemical cells and interconnectors. The SOFC-type high-temperature solid oxide fuel cell consists of a stack of the same type of basic units. This high-temperature technology is reversible, so the same stack can operate in electrolysis mode to produce hydrogen and oxygen from water and electricity, or in fuel cell mode to produce electricity from hydrogen and oxygen.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is usually a multi-layer ceramic assembly whose electrolyte is formed by an ionically conductive central layer, which is rigid, dense, sealed, and sandwiched between two porous layers forming the electrodes. It should be noted that additional layers may be present, but these only serve to improve one or more of the layers already described.

[0010] The electrical and fluidic interconnection device is an electronic conductor that ensures, from an electrical point of view, the connection of the electrochemical cells of each basic unit in the stack of basic units, the electrical contact between one face of the cell and the cathode and between the other face of the next cell and the anode, and, from a fluidic point of view, the supply of reagents and the discharge of products for each of the cells. The interconnect thus ensures the function of supplying and collecting electric current and separates the gas circulation chambers for distribution and / or collection.

[0011] More specifically, the main function of the interconnector is to ensure not only the passage of electric current but also the circulation of gases (i.e., injected steam, extracted hydrogen and oxygen for HTE electrolysis, air and fuel with injected hydrogen and extracted water for SOFC cells) near each cell, as well as to separate the anode and cathode chambers of two adjacent cells, which are the gas circulation chambers on the anode and cathode sides of the cells, respectively.

[0012] In particular, in a SOEC type high temperature solid oxide electrolyser, the cathode chamber contains water vapor and hydrogen produced from the electrochemical reaction, while the anode chamber contains exhaust gases, if present, and oxygen, another product of the electrochemical reaction. In a SOFC type high temperature solid oxide fuel cell, the anode chamber contains the fuel, while the cathode chamber contains the fuel.

[0013] To perform high temperature steam electrolysis (HTE), water vapor (HO) is injected into the cathode chamber. Under the effect of an electric current applied to the cell, dissociation of water molecules in the form of water vapor takes place at the interface between the hydrogen electrode (cathode) and the electrolyte, which dissociates into dihydrogen gas (H2) and oxygen ions (O 2- ) is produced. Dihydrogen (H2) is collected and discharged at the exit of the hydrogen chamber. Oxygen ions (O 2- ) migrates through the electrolyte and recombines into dioxygen (O2) at the interface between the electrolyte and the oxygen electrode (anode). The oxygen produced in gas form can be collected at the anode, as an exhaust gas, such as air, circulates at the anode.

[0014] To ensure the operation of a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode chamber of the cell and hydrogen into the anode chamber. The oxygen in the air is O 2- The hydrogen dissociates into hydrogen ions. These ions move through the electrolyte from the cathode to the anode and oxidize the hydrogen, forming water and simultaneously producing electricity. In a SOFC cell, the water vapor is in the dihydrogen compartment (H2), just like in a SOEC electrolysis. Only the polarity is reversed.

[0015] For illustrative purposes, a schematic diagram illustrating the working principle of an SOEC type high temperature solid oxide electrolyser is shown in Figure 1. The function of such an electrolyser is to convert water vapor into hydrogen and oxygen according to the following electrochemical reaction: 2H2O → 2H2+ O2

[0016] This reaction is carried out electrochemically in the cells of an electrolyser. As shown diagrammatically in FIG. 1, each elementary electrolysis cell 1 is formed of a cathode 2 and an anode 4, arranged on either side of a solid electrolyte 3. The two electrodes (cathode and anode) 2 and 4 are electronic and / or ionic conductors, made of porous materials, and the electrolyte 3 is gas-tight, an electronic insulator and an ionic conductor. In particular, the electrolyte 3 is an anion conductor, more specifically O 2- The electrolysis device can then be a proton electrolyte (H +) are called anion electrolysis devices.

[0017] The electrochemical reactions take place at the interfaces between each of the electronic conductors and the ionic conductor.

[0018] At cathode 2 the half-reactions are: 2H2O + 4e - → 2H2+ 2O 2-

[0019] At anode 4, the half-reactions are: 2O 2- → O2+ 4e -

[0020] The electrolyte 3 interposed between the two electrodes 2 and 4 converts O 2- This is the site where ions move.

[0021] Water vapor can accompany the hydrogen H2 at the cathode inlet and water vapor can accompany the hydrogen produced and collected at the outlet, as shown in brackets in Figure 1. Similarly, an exhaust gas such as air can be injected at the anode side inlet to evacuate the produced oxygen, as shown by the dotted line. An additional function of the injection of the exhaust gas is to act as a thermal moderator.

[0022] The basic electrolysis device, or electrolysis reactor, consists of a basic cell as described above, with a cathode 2, an electrolyte 3 and an anode 4, as well as two interconnects ensuring the functions of electrical and fluid distribution.

[0023] To increase the flow rate of hydrogen and oxygen produced, it is known to stack several elementary electrolysis cells one on top of the other, separated by an interconnector, and this assembly is placed between two end interconnect plates that support the power supply and the gas supply of the electrolyzer (electrolysis reactor).

[0024] Thus, a high-temperature solid oxide electrolyser of the SOEC type comprises at least one, and usually several, electrolysis cells stacked one on top of the other, each elementary cell being formed by an electrolyte, a cathode and an anode, the electrolyte being interposed between the anode and the cathode.

[0025] As previously indicated, a fluidic and electrical interconnect device in electrical contact with one or more electrodes generally provides current supply and collection functions and defines one or more gas circulation chambers.

[0026] The function of the so-called cathode compartment is therefore the distribution of electric current and of water vapor, as well as the recovery of hydrogen in contact with the cathode.

[0027] The function of the so-called anode chamber is the distribution of the electric current as well as the recovery of the oxygen produced at the adjacent anode, possibly with the aid of exhaust gases.

[0028] Figure 2 shows an exploded view of a basic unit of a high-temperature solid oxide electrolyser of the SOEC type according to the prior art. The electrolyser comprises a number of elementary electrolysis cells C1, C2 of the solid oxide cell (SOEC) type, stacked one on top of the other with interconnects 5. Each cell C1, C2 consists of a cathode 2.1, 2.2 and an anode (only the anode 4.2 of cell C2 is shown) between which an electrolyte is arranged (only the electrolyte 3.2 of cell C2 is shown).

[0029] The interconnector 5 is a part made of a metal alloy that ensures the separation between the cathode chamber 50 and the anode chamber 51, defined by the volumes contained between the interconnector 5 and the adjacent cathode 2.1 and between the interconnector 5 and the adjacent anode 4.2, respectively. It also ensures the distribution of gas to the cells. The injection of water vapor to each basic unit is carried out in the cathode chamber 50. The collection of the hydrogen produced in the cathodes 2.1, 2.2 and of the residual vapor is carried out in the cathode chamber 50 downstream of this, after the dissociation of the water vapor by the cells C1, C2. The collection of the oxygen produced in the anode 4.2 is carried out in the anode chamber 51 downstream of this, after the dissociation of the water vapor by the cells C1, C2. The interconnector 5 ensures the passage of electric current between the cells C1 and C2 by direct contact between the adjacent electrodes, i.e. the anode 4.2 and the cathode 2.1.

[0030] To ensure good electrical contact between all of the interconnects, the electrochemical cells and the interconnects are sandwiched between two rigid plates, the so-called upper and lower end plates, which are electrically insulated from the interconnects. The sandwich thus formed is the so-called "stack" and therefore corresponds to an assembly comprising upper and lower end plates, the electrochemical cells and the interconnects. This stack should be kept under compressive force to ensure good electrical continuity of the contact surfaces between the plates.

[0031] During the first stage of stack fabrication, the formation of the glass-ceramic seal is facilitated by subjecting the stack to a thermal cycle, called the conditioning cycle, while a controlled compressive force is applied to the stack.

[0032] In fact, the various seals between the circuits are ensured by seals made of molten glass. This molten glass is obtained by depositing a slip, a precursor of glass. The slip is deposited in the form of beads sandwiched between the interconnect plates (or interconnectors). This slip is then dried in place to create beads of glass powder. Thus, when cold, the interconnect plates are separated by dry slip beads, before the temperature increase cycle that will result in the formation of the glass. These beads will melt during the heating cycle, establishing contacts in the aforementioned reaction zones. As a result of the melting of the beads, the thickness of the slip beads can be reduced by more than 50%. These beads can also be made of already dense glass sandwiched between two successive interconnectors of the stack. Just as during the conditioning cycle with the dry slip beads, the melting of the glass seal will cause the space between the interconnectors to shrink, but to a lesser extent than the slip.

[0033] In both cases, it is important to ensure guidance according to a direction perpendicular to the plane of the interconnects or collinear with the direction of the compressive forces of the interconnection plates and of the end plates. Such guidance makes it possible to ensure that the components of the stack (especially the interconnects, the insulating plates, the end plates) remain correctly aligned relative to one another during the shrinkage of the stack, which occurs during the forming of the glass. During this stage, the height of the stack is effectively reduced by 50%, which results in a significant vertical movement of the stack.

[0034] The development of industrial systems incorporating high-temperature electrolysers involves an increase in the volume of gas to be processed (in SOEC or SOFC). To do so, an increase in the surface area, the number of cells and of interconnects is necessary. However, a significant increase in the number of plates and therefore in the height of the stack creates many technical difficulties, especially during the manufacturing stage. Indeed, the greater the stack height, the more critical the control of the guidance becomes.

[0035] In the current design, this guidance is ensured by cylindrical columns placed inside the stack structure passing through different plates, in which cylindrical or rectangular holes are machined that closely match the diameter of the columns, the bases of these columns being mechanically blocked in the lower end plate.

[0036] This type of device has various limitations related to the small diameter of the guide posts imposed by the internal structure of the interconnector. Obtaining a satisfactory guiding of a large number of thin plates over a large height by this type of post involves a fine control of the relative gap between the posts and the diameter of the through holes. With the narrow gap, this type of assembly is exposed to the risk of mis-centering during rotations that may occur during the cycle of formation of the sealing glass ceramic, during which the stack undergoes a significant contraction of its height. It should be noted that the forces applied to ensure the contact of the different plates are not very large, so that any inadvertent jamming of a plate against its guiding elements becomes problematic. In addition, this type of guiding also involves the operation of cutting off the posts that protrude from the stack after adjustment, which cannot be removed after the thermal cycle and remain in the stack.

[0037] For illustration, Figures 3A and 3B show a current guiding solution. Two pillars 11 and 12 are used to guide the plates P of the stack 20 (shown here very diagrammatically) during their descent. The plates P can consist of interconnection plates, insulating plates or lower and upper end plates. In this case, in Figure 3B, for example, the upper and lower end plates P are shown, and the other plates P sandwiched between them are therefore not shown. On one side, an opening O1 of circular cross section is used, the adjustment between the plate P and the pillars 11 is very fine, for example the gap J1 is in the range of 0.1 mm. On the other side, the opening O2 in the plate P has a rectangular cross section, leaving a larger gap J2. Then, as the glass-ceramic seal melts, a slight bending of these plates P is caused by pushing them in the middle, following the arrow F, which may cause a blockage due to off-centering at the pillars 11 with a tight adjustment, represented by AC in Figure 3B. In fact, to avoid the risk of AC being mis-centered, the gap J1 around the periphery of the guide post 11 could be increased considerably, but this would then radically reduce the guiding function, which is undesirable.

[0038] There is therefore a need to propose an effective guiding solution that makes it possible to avoid this decentering problem while maintaining the guiding accuracy during shrinkage of the stack of plates. Summary of the Invention [Problem to be solved by the invention]

[0039] The present invention aims to at least partially address the above-mentioned needs and shortcomings associated with prior art embodiments. [Means for solving the problem]

[0040] The object of the present invention is therefore, according to one of its aspects, to provide a method for producing a method for the treatment of a pulmonary arthritis, comprising: A stack of SOEC / SOFC type solid oxide cells operating at high temperature, comprising a plurality of plates stacked one on top of the other according to a vertical direction substantially perpendicular to the horizontal extent of each plate, each plate including an upper surface, a lower surface and an outer side surface; The plurality of plates includes at least a plurality of electrochemical cells each formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of interconnectors each disposed between two adjacent electrochemical cells; an upper end plate and a lower end plate having a plurality of electrochemical cells and a plurality of interconnects sandwiched therebetween; a stack including: at least two guiding elements ensuring the guiding of at least a portion of the plates of the stack into a vertical stack; An assembly including: The at least two guide elements are characterised in that they extend vertically according to a vertical direction and bear against an outer side surface of each of the at least some of the plates.

[0041] The assembly according to the invention may further comprise one or more of the following features, taken separately or according to any technically possible combination:

[0042] In particular, each horizontal plane is defined by horizontal directions that are perpendicular to one another.

[0043] The at least two guide elements may be fixed by fixing devices to a lower support plate above which the stack is placed and / or to an upper support plate below which the stack is placed.

[0044] The fixing device may include a fixing base fixed to the lower support plate and / or the upper support plate, a compressible elastic return member having one end in contact with the guide element and the other end in contact with the fixed base, and a fixing screw attached to the base.

[0045] The compression-elastic return member can in particular be made of a metal alloy, in particular a metal superalloy, in particular nickel-based, for example Inconel® 718 or 750, or Haynes® 230®, or alternatively made of ceramic, for example by additive manufacturing.

[0046] In addition, each guide element may include a support device cooperating with the fixing device, in particular including at least one support plane of the compression-elastic return member and a support base in contact with the lower support plate and / or the upper support plate.

[0047] Furthermore, the at least two guide elements may have at least partially a substantially cylindrical shape and, in cross section relative to the vertical direction, may have a substantially circular, triangular, triangular and semicircular, square and / or rectangular shape.

[0048] In addition, the at least two guide elements, in particular with a rectangular cross section, can be evenly distributed around the circumference of each plate, in particular with the same number of guide elements per face of each plate. The at least two guide elements can be present in a number equal to at least 4, or 6, or 8, or more, in particular an even number. In the case of four guide elements, these can be arranged centrally with respect to each face of the plate. In the case of eight guide elements, two guide elements can be arranged on each side of each corner of a plate with four corners.

[0049] Each plate of said at least some of the plates may also include at least two notches formed over a side surface of the plate in which said at least two guide elements, in particular circular, elliptical or "V" shaped, bear.

[0050] At least some of the cutouts may each have a "V" shape obtained by forming two flat surfaces that meet the sides of the plate.

[0051] The "V" shape may define an angle comprised between 15° and 60°. The depth of the "V" shape, defined as the height of the "V" between the sides and the intersection of the two tangential surfaces, may be comprised between 2 mm and 15 mm, and may in particular range 10 mm.

[0052] The number of said at least two guide elements is comprised between two and twelve and may in particular be equal to four.

[0053] Also, said at least two guide elements may be held fixed together by at least one elastic element extending substantially perpendicular to the vertical direction.

[0054] Each elastic element may include a sliding element having one end fixed to a guide element, which is capable of sliding inside a fixed element having one end fixed to another guide element, the sliding element and the fixed element being connected together by at least one tensile elastic return member.

[0055] Additionally, the at least two guide elements may be made of at least one electrically insulating material.

[0056] Furthermore, another object of the invention, according to another of its aspects, is a method for adjusting a stack of SOEC / SOFT type solid oxide cells operating at high temperatures in an assembly as previously defined, characterized in that it comprises a step of guiding at least some of the plates constituting the stack into a vertical stack by means of said at least two guiding elements.

[0057] The invention can be better understood on reading the following detailed description of non-limiting examples of its implementation and on examining the accompanying schematic and partial figures. [Brief description of the drawings]

[0058] [Figure 1] FIG. 1 is a schematic diagram showing the operating principle of a high temperature solid oxide electrolyzer (SOEC). [Diagram 2]FIG. 1 is an exploded schematic view of a portion of a high temperature solid oxide electrolyzer (SOEC) including an interconnect according to the prior art. [Figure 3A] 1 shows, according to a top view, a schematic and partial representation of a prior art principle for guiding the plates of a high-temperature stack of the SOEC / SOFC type; [Figure 3B] 1 shows, according to a side view, a schematic and partial representation of a prior art principle for guiding the plates of a high-temperature stack of the SOEC / SOFC type; [Figure 4A] FIG. 1 shows, in a perspective view, an example of an assembly according to the invention, including a high-temperature SOEC / SOFC type stack and four guide elements. [Figure 4B] FIG. 4B is an enlarged view of B1 in FIG. 4A. [Diagram 5] FIG. 4B shows a detail of making a "V" shaped notch in the plates of the stack of FIG. 4A. [Figure 6] FIG. 4B is a detailed view of a fixing device on a lower support plate for the stack of FIG. 4A. [Figure 7] FIG. 7 is a top view of FIG. 6. [Figure 8] FIG. 4B shows a front view of the lower end plate of the stack of FIG. 4A. [Figure 9] FIG. 4B shows a guide element of the assembly of FIG. 4A according to a perspective view. [Figure 10] FIG. 13 shows a modified example of a guide element according to a perspective view. [Figure 11] FIG. 2 shows, according to a perspective view, another example of an assembly according to the invention comprising a high-temperature SOEC / SOFC type stack and four guide elements, in which elastic elements are used. [Figure 12] FIG. 12 is a top view of FIG. [Figure 13A] FIG. 12 shows an example of an elastic element of the assembly of FIG. 11 in a perspective view. [Figure 13B] This is a diagram according to B2 in FIG. 13A. [Figure 14] FIG. 2 shows in perspective view the stacking of the lower end plates of a stack of assemblies according to the invention; [Figure 15] FIG. 15 is a detail view of FIG. 14 showing the fixing device. [Figure 16] FIG. 13 is a detailed view showing the details of the fabrication of the fixation device. [Figure 17] FIG. 13 is a detailed view showing the details of the fabrication of the fixation device. [Figure 18] 13A and 13B are perspective views showing modified examples of guide elements; [Figure 19A] FIG. 2 shows an upper support plate and four guide elements in a perspective view. [Figure 19B] FIG. 19B is an enlarged view according to B3 of FIG. 19A showing the fixing device. [Figure 20A] FIG. 19B shows a variant of an assembly according to the invention including a high-temperature SOEC / SOFC type stack and four guide elements, using the upper support plate of FIG. 19A, according to a perspective view. [Figure 20B] FIG. 20B is an enlarged view of B4 in FIG. 20A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] In all these figures, the same reference numbers may indicate the same or similar elements.

[0060] In addition, in order to make the figures more readable, the different parts shown in the figures are not necessarily plotted according to uniform scale.

[0061] Figures 1 to 3 have already been described above in the prior art and in the section relating to the technical context of the present invention. It is clearly indicated that in Figures 1 and 2, symbols and arrows for the steam supply H2O, for the distribution and recovery of dihydrogen H2, oxygen O2, air and electric current are shown for the purposes of clarity and precision to explain the operation of the illustrated device.

[0062] Furthermore, it should be noted that all of the components (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramic, and the operating temperatures of SOEC / SOFC type high temperature stacks are usually comprised between 600 and 1000° C.

[0063] Additionally, any of the terms "upper", "lower", "horizontal" and "vertical" used herein should be understood according to the conventional direction of orientation of the SOEC / SOFC type stack when in its configuration of use.

[0064] 4A to 20B make it possible to show the principle of the outer guiding according to the invention. Compared to the principle of the inner guiding of the stack, the outer guiding has several advantages, especially for stacks with a large height. The integration of the cooling circuit passages arranged in the corners of the stack can be simplified due to their peripheral arrangement. In addition, the elimination of the inner guiding columns makes it possible to more easily consider adjusting several sub-stacks under the same press. In fact, in a configuration with integrated inner guiding, if the height of the stack is reduced, the columns protrude from the upper end plate and prevent the arrangement of a second stack on top of it. For this reason, this type of inner guiding does not make it possible to simultaneously manufacture assemblies of several independent sub-stacks stacked one on top of the other on the same bench. One advantage of the outer guiding according to the invention may also be the easy disassembly of the guiding columns, which allows a reduction in the size of the stack compared to the inner guiding, opening the way for new possibilities of the geometric configuration or of the internal design of the stack.

[0065] Thus, Figures 4A to 9 relate to a first embodiment of an assembly 80 according to the invention including a stack 20 of solid oxide cells of the SOEC / SOFC type operating at high temperatures.

[0066] The stack 20 consists of a number of plates P stacked one on top of the other according to a vertical direction Z, which is perpendicular to each of the plates P extending in a horizontal plane parallel to the horizontal plane containing the axes X and Y, as shown in FIG. 4A.

[0067] The stack 20 includes a plurality of electrochemical cells C1, C2, for example 100 electrochemical cells in this specification, each formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, as defined above, and a plurality of interconnectors 5 disposed between two adjacent electrochemical cells C1, C2, respectively. In addition, the stack 20 includes an upper end plate 42 and a lower end plate 41, between which the plurality of electrochemical cells C1, C2 and the plurality of interconnectors 5 are sandwiched.

[0068] For example, the plates P of the stack 20 can be formed by the electrochemical cells C1, C2, the interconnects 5, the upper end plate 42, the lower end plate 41 or, as shown in Fig. 5, an insulating plate 25, for example made of mica. Each of these plates P comprises a top surface Sp, a bottom surface Si and an outer side surface Sl, as shown in particular in Fig. 5. The outer side surface Sl connects the top surface Sp and the bottom surface Si.

[0069] Also, in order to achieve the outer guiding of the plates P into the vertical stack, the assembly 80 according to the invention comprises here four guiding elements 11, 12, 13, 14 in the form of guiding columns. In particular, the number of guiding elements may be comprised between 2 and 12 and preferably equal to 4.

[0070] These guide posts 11, 12, 13 and 14 extend vertically according to the vertical direction Z and bear against the outer side surface S1 of each plate P. In this way, the outer guiding is achieved by bearing against the outer faces of the stack.

[0071] In this example, each guide post 11, 12, 13, 14 is cylindrical and has a circular cross section relative to the vertical direction Z, as shown for example in figure 9. Alternatively, any other shape may be possible, in particular a square or rectangular shape.

[0072] In addition, each plate P of the stack 20 is substantially square with a side surface S1, and therefore includes four sides, each of which is formed with a notch V1, V2, V3, V4 in which a guide post 11, 12, 13, 14 rests.

[0073] Advantageously, these four cutouts V1, V2, V3 and V4 are in the shape of a "V" obtained by forming two planes that meet at the lateral sides. Alternatively, any other shape is possible, in particular a circular or elliptical shape. It is also possible that no cutouts are formed in the plate P.

[0074] Thus, the outer guiding is achieved here by a cylindrical post on a flat-edged support, specifically by forming the support between the cylindrical surface of one post and two tangential surfaces obtained by machining "V" shaped notches.

[0075] As shown in particular in figures 5 and 8, each cutout V1, V2, V3, V4 has a "V" shape that defines an opening angle α comprised between 15° and 60°. Advantageously, the same cutout type is formed in all of the plates P that make up the stack 20. The number of cutouts used here is four, ensuring guidance by an equal number of pillars 11, 12, 13, 14. Alternatively, it may be comprised between 2 and 12.

[0076] Also, as shown in FIG. 8, the depth Pv of the "V" shape of each notch V1, V2, V3, V4, defined as the height of the "V" between the side surface Sl and the intersection of the two tangential surfaces, is comprised between 2 mm and 15 mm, in particular in the range of 10 mm. This depth Pv can be adjusted according to the specific geometric constraints of the stack 20 and the desired guiding height. Also, depending on the selected depth Pv, several diameters of the guiding pillars can be taken into account while maintaining a shape that makes it possible to ensure tangential support between the cylindrical surface and the support surface formed by the "V" machined on the edge of the plate P. The position of the notches V1, V2, V3, V4 can be freely chosen and adapted to the shape of the plate P, but each of the notches is preferably associated with another notch arranged substantially diametrically (or diagonally) opposite.

[0077] It should be noted that different shapes of "V" can be used for all or some of the cutouts V1, V2, V3, V4, in particular circular or elliptical shapes. In particular, a circular shape may make it possible to have a single contact point so as to limit friction with the "V" shape. Advantageously, the diameter of the cutout, or its maximum lateral direction, should be even larger than that of the guide posts.

[0078] It is also advantageous to fasten the guide posts 11, 12, 13, 14 to the lower support plate 30 and / or the upper support plate 31 by means of fastening devices 50 in order to ensure sufficient support contact whilst allowing for coplanar movement of the plates P due to expansion during the stage of manufacturing the sealing glass ceramic.

[0079] More specifically, in order to ensure continuous support and guidance of the columns 11, 12, 13, 14 relative to the plate P without generating significant stresses that could lead to their mis-centering, the columns are attached to at least one support plate 30, 31 with interfaces making it possible to ensure the following mechanical functions: maintaining the verticality of the columns and their vertical blockage, their translation in the axis of movement of the face of the stack and compression of the elastic elements supported by them.

[0080] In this example of figures 4A to 9, a fixing device 50 is provided at the base of each guide pillar 11, 12, 13, 14 to ensure the mechanical support of the pillar relative to the stack 20 while integrating elastic elements, as shown in particular in figures 6 and 7. Each fixing device 50 is therefore fixed to a support plate of the production bench, namely the lower support plate 30, which corresponds here to the manifold.

[0081] Thus, each fixing device 50 includes a fixed base 51 or heel fixed to the lower support plate 30, a compressible elastic return member 52, herein a compression spring (or alternatively a set of washers) having one end in contact with the guide post 11, 12, 13, 14 and the other end in contact with the fixed base 51, and a fixing screw 53 attached to the base 51, which allows fixing and adjustment.

[0082] Most of the vertical contraction movements of the stack 20 observed in the stack during the stage of forming the glass ceramic occur in the temperature range comprised between 650°C and 750°C. These temperatures are lower than the maximum temperatures reached during the manufacturing cycle, which makes it possible to consider the use of metallic compression springs 52 that maintain mechanical properties that are still sufficient to ensure the compression force. The compression springs 52 can therefore be made of metallic superalloys, for example nickel-based, for example Inconel® 718 or 750, that are used industrially to manufacture springs for applications at very high temperatures. In addition, the fact that the elastic and mechanical properties of the constituent material of the springs are significantly reduced at temperatures higher than 750°C is not of itself a problem, as long as the guiding constraints are relieved, since the movements of the stack 20 above this temperature are low. The compression springs 52 can be of the meltable type intended for one-time use that ensures mechanical functionality for temperatures lower than 750°C. They can therefore be of any material that maintains good elastic properties at these temperatures and has low creep. For example, the compression spring 52 may be of a metallic superalloy of the Haynes® 230® type, or of a ceramic obtained, for example, by additive manufacturing.

[0083] Furthermore, each guide post 11, 12, 13, 14 is embedded and fixed to the lower support plate 30, or to a support plate of the production bench, and possibly also to the lower end plate 41, so that the post is also modified at its base.

[0084] Thus, as shown in particular in Figure 9, each guide element 11, 12, 13, 14 comprises a support device 60 cooperating with the fixing device 50. This support device 60 comprises a flat-shaped support surface 61 enabling the support of the compression spring 52, and a support base 62 in contact with the lower support plate 30. Furthermore, the lower end of the pillar corresponds to a lower guide stud 64 on which a circlip-type blocking ring 65 is provided.

[0085] In this assembly type, the positions and the relative gaps between the columns 11, 12, 13, 14 and the plates P of the stack 20 should be dimensioned taking into account the expansion of the different elements of the assembly. Preferably, the material of the guide columns may consist of a material having the same expansion coefficient as the stack 20, i.e. for example a ferritic steel, for example of the VDM® Crofer or K41® type, and preferably also of the same material as the lower support plate 30 or the support plate of the production bench.

[0086] Advantageously, each guide pillar 11, 12, 13, 14 has a contact point as small as possible to limit friction. To ensure this contact point, pillars of circular cross section can be selected, as in figure 9. Alternatively, pillars of triangular, or in this case semi-triangular and semi-circular shape can be used, as shown in figure 10. In this case, the pillar has a support edge 66 that directly contacts its side surface Sl, without any need to form a cutout in the plate P.

[0087] Guidance can also be achieved using additional elastic elements to hold the posts 11, 12, 13, 14 in place, as shown in Figures 11 to 13B.

[0088] Thus, the two guide posts 11, 12 and 13, 14 may be held fixed together by elastic elements 70 and 71, respectively, extending transversely to the vertical direction Z.

[0089] These elastic elements 70 and 71 may be selected to maintain their elasticity as high as possible up to at least 750°C.

[0090] Each elastic element 70, 71 thus comprises a sliding bar 81 having one end 84 in the form of a mounting ring fixed to the post 12 or 13 and capable of sliding within a fixed bar 82 having one end 85 in the form of a mounting ring similarly fixed to another post 11 or 14, according to the double arrow F seen in FIG. 13A.

[0091] The sliding bar 81 and fixed bar 82 are connected together by a tension spring 83 attached to a pin 88 on the bars 81,82.

[0092] Advantageously, these elastic elements 70, 71 make it possible to keep the pillars parallel to one another during stacking. They make it possible to avoid or limit any slippage and deformation of the pillars during the movement of the stack. They are of the fusible type and can be made of the same high-temperature material as the pillars.

[0093] 14 to 17 show the stacking of the lower end plate 41 on the lower support plate 30 and the fixing of the columns 11 , 12 , 13 and 14 on the lower support plate 30 by four fixing devices 50 .

[0094] Complementing what has been explained previously, in figure 15 it can be seen that the lower support plate 30 includes a counterbore 92 and a flat surface 91 allowing guiding of the post and of the base 51 or heel. The base 51 ensures the verticality of the post, and a guide stud 64 machined to receive a circlip 65 (or any other equivalent, e.g. a pin or clamping ring) is inserted into the counterbore 92 to ensure vertical blocking and protrudes beyond the thickness of the plate 30.

[0095] This mounting, as shown in Figures 14 to 17, allows the stack 20 to be centered on the bench to allow the initial setup of the mounting with the axis of the applied force. Verticality is ensured by the base 62 and blocking by a ring 65 attached to the end of the post protruding from the plate 30. Guided translational movement of the post is ensured by sliding the base 62 in a rectangular slot or counterbore 92 machined in the plate 30. Retention and compression of the compression spring 52 is ensured by a fixed base 51, whose position is blocked laterally by a flat surface 91. Screws 53 allow the compression level of the spring 52 to be adjusted.

[0096] The assembly 80 is intended to assemble the stack 20 so as to ensure guidance during the thermal cycle to form the glass-ceramic seal. To enable its use in the context of the conditioning cycle, including tensioning of the stack, each pillar 11, 12, 13, 14 can be made of at least one electrically insulating material to avoid short-circuiting of the different stages of the stack. Any insulating material can be used, such as ceramic materials, in particular metallic materials that become insulators after heating, such as alumina, Macol® or aluminoforming, as well as any material that is initially conductive but is covered with an insulating layer.

[0097] Preferably, each guide post 11, 12, 13, 14 may be made of VDM® Crofer, which allows it to have the same thermal expansion coefficient as that of the stack 20, and may be covered with a layer of insulating material that withstands high temperatures, such as yttriated zirconia.

[0098] Alternatively, each pillar 11, 12, 13, 14 can be made in two parts as illustrated by figure 18. Thus, for example, pillar 11 can include a first part 11a, for example made of alumina, and a second metallic part 11b, the two parts being connected by a screw, welded or brazed connection Lfb.

[0099] The above-described principles of fastening to the lower support plate 30 can also be applied to the upper support plate 31 as shown by Figures 19A to 20B for cylindrical mold stack 20 geometries.

[0100] The upper support plate 31 comprises a central base 95 of a support ball joint and four fixing devices 50 making it possible to fix the four guide posts 11, 12, 13 and 14.

[0101] In this cylindrical shape of the stack 20, the columns can rest directly on the side S1 of the plate P without requiring the presence of a notch. Larger column diameters can also be used with this support type. It should be noted that this type of construction, which is placed on top of the stack 20 rather than fixed to the lower support plate 30, can also be adapted for straight edged stacks, as previously mentioned.

[0102] Of course, the invention is not limited to the embodiment just described, as various modifications thereto can be made by those skilled in the art. [Explanation of symbols]

[0103] 1 Electrolysis cell 2 Cathode 3 Solid electrolyte 4 Anode 20 Stack 80 Assembly 5 Interconnector 11, 12, 13, 14 Guideposts 11a First Part 11b Second metal part 25 Insulation plate 30 Lower support plate 31 Upper support plate 41 Lower end plate 42 Upper end plate 50 Fixation device 51 Fixed base 52 Compression spring 53 Fixing screw 60 Support device 61 Support plane 62 Support Base 64 Guide stud 65 Circlip Ring 66 Support Edge 70, 71 Elastic elements 81 Sliding bar 82 Fixed bar 83 Tension Spring 84 Mounting ring 85 Mounting Ring 88 pin 91 Flat surface 92 Counterbore 95 Central Base C1, C2 electrochemical cells P-Plate Sp top surface Si bottom surface Sl outer side V1, V2, V3, V4 notches Z vertical direction Pv Depth

Claims

1. A stack (20) of SOEC / SOFC type solid oxide cells operating at high temperatures, comprising a plurality of plates (P) stacked one on top of the other along a vertical direction (Z) substantially perpendicular to the extent of each horizontal surface of each plate (P), each plate (P) comprising an upper surface (Sp), a lower surface (Si) and an outer side surface (Sl); The plurality of plates (P) include at least a plurality of electrochemical cells (C1, C2) each formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of interconnectors (5) respectively disposed between two adjacent electrochemical cells (C1, C2); an upper end plate (42) and a lower end plate (41) between which the plurality of electrochemical cells (C1, C2) and the plurality of interconnectors (5) are sandwiched; a stack (20) including: at least two guide elements (11, 12, 13, 14) ensuring the guidance of at least some of the plates (P) of the stack (20) into a vertical stack; Including, the at least two guide elements (11, 12, 13, 14) extend vertically according to the vertical direction (Z) and bear against the outer side (S1) of each plate (P) of at least some of the plates (P), Assembly (80).

2. 2. The assembly according to claim 1, characterized in that the at least two guide elements (11, 12, 13, 14) are fixed by fixing devices (50) to a lower support plate (30) on which the stack (20) is arranged and / or to an upper support plate (31) on which the stack (20) is arranged.

3. 3. The assembly according to claim 2, characterized in that the fixing device (50) comprises a fixing base (51) fixed to the lower support plate (30) and / or to the upper support plate (31), a compressible elastic return member (52) one end of which is in contact with the guide element (11, 12, 13, 14) and the other end of which is in contact with the fixing base (51), and a fixing screw (53) attached to the base (51).

4. Assembly according to claim 3, characterized in that the compression-elastic return member (52) is made of a metal alloy, in particular a metallic superalloy, in particular nickel-based, for example Inconel® 718 or 750, or Haynes® 230®, or is made of ceramic, for example by additive manufacturing.

5. 5. An assembly according to claim 3 or 4, characterized in that each guide element (11, 12, 13, 14) comprises a support device (60) cooperating with said fixing device (50), comprising at least one support plane (61) of said compression-elastic return member (52) and a support base (62) in contact with said lower support plate (30) and / or said upper support plate (31).

6. 6. An assembly according to any one of claims 1 to 5, characterized in that the at least two guide elements (11, 12, 13, 14) have at least partly a substantially cylindrical shape and, in cross section relative to the vertical direction (Z), have a substantially circular, triangular, triangular and semicircular, square and / or rectangular shape.

7. 7. An assembly according to any one of claims 1 to 6, characterized in that each plate (P) of at least some of the plates (P) comprises at least two notches (V1, V2, V3, V4) formed over the side (S1) of the plate (P), in which the at least two guide elements (11, 12, 13, 14), in particular of circular, elliptical or "V" shape, bear.

8. 8. An assembly according to claim 7, characterized in that each of at least some of the notches (V1, V2, V3, V4) has a "V" shape obtained by forming two planes tangent to the side surface (S1) of the plate (P).

9. 9. An assembly according to claim 8, characterized in that said "V" shape defines an angle (α) comprised between 15° and 60°.

10. 10. An assembly according to claim 8 or 9, characterized in that the depth (Pv) of the "V" shape, defined as the height of the "V" between the side surface (Sl) and the intersection of the two tangential surfaces, is comprised between 2 mm and 15 mm, in particular in the range of 10 mm.

11. Assembly according to any one of claims 1 to 10, characterized in that the number of said at least two guide elements (11, 12, 13, 14) is comprised between 2 and 12, in particular equal to 4.

12. Assembly according to any one of claims 1 to 11, characterized in that the at least two guide elements (11, 12, 13, 14) are fixedly held together by at least one elastic element (70, 71) extending substantially perpendicular to the vertical direction (Z).

13. Stack according to claim 12, characterized in that each elastic element (70, 71) comprises a sliding element (81) with one end (84) fixed to a guide element (11, 12, 13, 14) that can slide inside a fixed element (82) with one end (85) fixed to another guide element (11, 12, 13, 14), said sliding element (81) and fixed element (82) being connected together by at least one tensile elastic return member (83).

14. Stack according to any one of claims 1 to 13, characterized in that the at least two guide elements (11, 12, 13, 14) are made of at least one electrically insulating material.

15. 15. A method for adjusting a stack (20) of SOEC / SOFT solid oxide cells operating at high temperatures of an assembly (80) according to any one of claims 1 to 14, characterized in that it comprises a step of guiding at least some of the plates (P) constituting the stack (20) into a vertical stack by means of the at least two guide elements (11, 12).

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