Assembly with SOEC / SOFC type solid oxide stack, bonding system and heat exchange system

Abstract

The main subject of the present invention is an assembly (100) comprising an SOEC / SOFC type solid oxide stack (20), a crimping system (60) for crimping the stack (20) comprising at least two crimping rods (55) that can be used to assemble an upper crimping plate (45) and a lower crimping plate (46), and a coupling system (30) for high-temperature, fluid-tight coupling of said stack (20) to a heating system (10) for supplying and discharging gases. This assembly (100) is characterized in that the coupling system (30) comprises collectors (31) with collection ducts (32) for supplying and discharging gases, each of which is provided with a collection port (33) located facing a corresponding communication port (34) of at least one of the upper crimping plate (45) and the lower crimping plate (46), and seals (35) located between the collection port (33) and the corresponding communication port (34).

Description

[Technical field]

[0001] The present invention relates to the general fields of high temperature water (HTW) electrolysis, in particular high temperature steam (HTWV) electrolysis, carbon dioxide (CO2) electrolysis, also co-electrolysis of high temperature water (HTW) and carbon dioxide (CO2), respectively, termed "high temperature electrolysis" (HTE) and "high temperature steam electrolysis" (HTSE).

[0002] More precisely, the invention relates to the field of high-temperature solid oxide electrolysers, commonly called "Solid Oxide Electrolysis Cells" (SOECs).

[0003] The present invention also relates to the field of high temperature solid oxide fuel cells, commonly referred to as "solid oxide fuel cells" (SOFCs).

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

[0005] More precisely, the invention relates to an assembly comprising a solid oxide stack of the SOEC / SOFC type, a clamping system for said stack and a high temperature sealed coupling system for said stack, as well as to a system including such an assembly and a heating system coupled to said stack through such a coupling system. [Background technology]

[0006] Within the scope of the SOEC-type high-temperature solid oxide electrolyzer, the objective is to convert water vapor (H2O) into dihydrogen (H2) and dioxygen (O2) and / or further convert carbon dioxide (CO2) into carbon monoxide (CO) and dioxygen (O2) in the same electrochemical device by electric current. Within the scope of the SOFC-type high-temperature solid oxide fuel cell, this operation is the reverse of generating electric current and heat by being supplied with dihydrogen (H2) and dioxygen (O2), typically air and natural gas, i.e. methane (CH4). For simplicity, the following description will specifically focus on the operation of the SOEC-type high-temperature solid oxide electrolyzer performing water electrolysis. However, this operation is also applicable to carbon dioxide (CO2) electrolysis and even to the co-electrolysis of high-temperature water (HTW) and carbon dioxide (CO2). Furthermore, this operation is transposable to the case of the SOFC-type high-temperature solid oxide fuel cell.

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

[0008] To perform high temperature water (HTW) electrolysis, 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 metal alloy interconnection plates, also called bipolar plates or interconnectors. Each electrochemical cell is sandwiched between two interconnection plates. The SOEC type high temperature solid oxide electrolyzer is therefore an alternating stack of electrochemical cells and interconnectors. The SOFC type high temperature solid oxide fuel cell consists of the same stack of basic units. As this high temperature technology is reversible, the same stack can operate in electrolysis mode to generate hydrogen and oxygen from water and electricity, and in fuel cell mode to generate electricity from hydrogen and oxygen.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a ceramic multi-layer assembly in which the electrolyte is formed by an ionically conductive central layer, which is a dense solid and is sealed and sandwiched between both porous layers forming the electrodes. It should be noted that further layers can be present, but these can only be used to improve one or more of the layers already described.

[0010] The interconnection devices, electrical devices and fluidic devices are, from an electrical point of view, electronic conductors that ensure the connection of each electrochemical cell of the elementary units in the stack of elementary units, ensuring the electrical contact between a face and the cathode of the cell and between the other face and the anode of the next cell, and thus, from a fluid point of view, combining the production of each of the cells. The interconnectors therefore ensure the current supply and collection functions and delimit the gas circulation compartments for distribution and / or collection.

[0011] More precisely, the main function of the interconnector is to ensure the flow of electric current, but also the gas circulation in the vicinity of each cell (i.e., injected water vapor, hydrogen, and oxygen extracted for HTW electrolysis, air and fuel with injected hydrogen and extracted water for SOFC cells) and to separate the anode and cathode compartments of two adjacent cells, which are the gas circulation zones for the anode and cathode sides of the cells, respectively.

[0012] In particular, for a SOEC type high temperature solid oxide electrolyser, the cathode compartment contains the products of the electrochemical reaction, water vapor and hydrogen, while the anode compartment contains the purge gas, if present, and the other product of the electrochemical reaction, oxygen. For a SOFC type high temperature solid oxide fuel cell, the anode compartment contains the fuel, while the cathode compartment contains the oxidant.

[0013] To perform high temperature water (HTW) steam electrolysis, water vapor (HO) is injected into the cathode compartment. Under the effect of an electric current applied to the cell, dissociation of water molecules as water vapor takes place at the interface between the hydrogen electrode (cathode) and the electrolyte, i.e., this dissociation produces dihydrogen gas (H2) and oxygen ions (O 2- ) and dihydrogen (H2) are collected and released from the hydrogen compartment. Oxygen ions (O 2- ) migrates through the electrolyte and is recombined as dioxygen (O2) at the interface between the electrolyte and the oxygen electrode (anode). A purge gas, such as air, can be circulated at the anode to collect the oxygen evolved in gaseous form at the anode.

[0014] To ensure the operation of a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode compartment of the cell and hydrogen is injected into the anode compartment. Oxygen from the air dissociates into ions O 2- These ions migrate through the electrolyte at the cathode to the anode, where they migrate to the oxide hydrogen and form water with the simultaneous generation of electricity. In a SOFC cell, and also in SOEC electrolysis, water vapor is placed in the dihydrogen (H2) compartment. Only the polarity is reversed.

[0015] As an example, Figure 1 shows a schematic diagram illustrating the theory of operation of a SOEC type high temperature solid oxide electrolyser. The function of such an electrolyser is to convert water vapor into hydrogen and oxygen according to the following electrochemical reactions: 2H2O→2H2+O2.

[0016] This reaction takes place electrochemically in an electrolytic cell. As shown in FIG. 1, each elementary electrolytic cell 1 is formed by a cathode 2 and an anode 4, placed on either side of a solid electrolyte 3. Both electrodes (cathode and anode) 2 and 4 are electronic and / or ionic conductors, made of a porous material, while the electrolyte 3 is gas-tight, electronically insulating and ionically conductive. The electrolyte 3 is in particular an anion conductor, more precisely an anion conductor, which is capable of absorbing ions O 2- The electrolytic cell may therefore be a proton electrolyte (H+ ) are called anion electrolytic cells.

[0017] An electrochemical reaction occurs at the interface 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 the anode 4, the half-reactions are: 2O 2- →O2+4e - .

[0020] The electrolyte 3 interposed between both electrodes 2 and 4 converts ions O under the effect of an electric field caused by the potential difference between the anode 4 and the cathode 2. 2- It is a place of movement for.

[0021] As illustrated in brackets in Figure 1, the water vapor input into the cathode is accompanied by hydrogen H2, and the hydrogen produced and recovered as output may be entrained with the water vapor. Similarly, as illustrated by the dotted line, a purge gas such as air may be further injected as an input to release the produced oxygen. An additional function of the purge gas injection is to act as a temperature regulator.

[0022] The basic electrolytic cell, or electrolytic reactor, consists of a basic cell as described above, equipped with a cathode 2, an electrolyte 3, an anode 4 and two interconnectors ensuring the electrical, hydraulic and thermal distribution functions.

[0023] To increase the flow rate of hydrogen and oxygen produced, it is known to stack several elementary electrolysis cells, separated by interconnectors, the whole being positioned between two terminal interconnect plates which support the power and gas supplies for the electrolyzer (electrolysis reactor).

[0024] Thus, a high-temperature solid oxide electrolyser of the SOEC type comprises at least one, and generally a plurality, of stacked electrolytic cells, 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 already indicated, a fluidic and electrical interconnection device in electrical contact with one or more electrodes generally ensures the current supply and collection functions and defines the boundaries of one or more gas circulation compartments.

[0026] The function of the so-called cathode compartment is therefore to distribute the electric current and water vapor, and also to recover the hydrogen at the cathode in contact therewith.

[0027] The function of the so-called anode compartment is to distribute the electric current and possibly also to recover the oxygen evolved at the anode in contact therewith, using a purge gas.

[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 electrolysis (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 represented), between which an electrolyte is disposed (only the electrolyte 3.2 of cell C2 is represented).

[0029] The interconnector 5 is a metal alloy component that ensures the separation between the cathode 50 and anode 51 compartments, and is 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 into each elementary unit is carried out in the cathode compartment 50. The collection of hydrogen and residual water vapor generated at the cathodes 2.1, 2.2 is carried out in the cathode compartment 50 downstream of the cells C1, C2, after the water vapor has been dissociated thereby. The collection of oxygen generated at the anode 4.2 is carried out in the anode compartment 51 downstream of the cells C1, C2, after the water vapor has been dissociated thereby. The interconnector 5 ensures the flow of current between the cells C1 and C2 by direct contact with the adjacent electrodes, between the anode 4.2 and the cathode 2.1.

[0030] The operating conditions of high temperature solid oxide electrolyzers (SOECs) are very close to those of solid oxide fuel cells (SOFCs), so the technological limitations are the same.

[0031] Therefore, proper operation of such SOEC / SOFC type solid oxide stacks operating at high temperatures mainly requires the fulfilment of the requirements set out hereinafter.

[0032] First, electrical insulation between two successive interconnects is necessary, as otherwise the electrochemical cell would short-circuit, but also a good electrical contact and a sufficient contact surface area between the cell and the interconnect. The goal is to have the lowest possible ohmic resistance between the cell and the interconnect.

[0033] In addition, a seal should be provided between the anode and cathode compartments, otherwise recombination of evolved gases will occur, resulting in hot spots that reduce efficiency and even damage the stack.

[0034] Finally, proper gas distribution, both as input and as product withdrawal, is important as failure to do so can result in efficiency losses, pressure and temperature inhomogeneities in the different basic units, or even unacceptable degradation of the electrochemical cells.

[0035] Gases entering and leaving a high temperature electrolysis (SOEC) or fuel cell (SOFC) stack operating at high temperatures can be managed through suitable devices in a furnace as illustrated with reference to FIG.

[0036] The furnace 10 thus comprises a cold part PF and a hot part PC, the latter comprising a furnace bottom 11 for a high temperature electrolysis (SOEC) or fuel cell (SOFC), a loop tube 12 for managing the gas inlets and outlets, and a stack.

[0037] The connection of the gas supply and exhaust devices is most often made at the cold part PF, in particular through double-ring mechanical crimp connectors, VCR® metal seal surface sealing connectors, welded joints or even sealing bushings in the partition.

[0038] In the case of the double ring mechanical crimp connection, both rings separate the sealing and crimping functions of the tube. The front ring forms the seal, while the rear ring allows the front ring to advance axially and performs the actual crimping of the tube radially. This principle makes it possible to achieve a very good tube crimp and a very good gas leakage seal. Moreover, its installation is easy and has a very good resistance to fatigue caused by vibrations. Engagement and disengagement are instantaneous in the absence of welding. However, its major drawback is precisely that it does not have the high temperature resistance that the rear ring, the front ring and the tube can be welded by diffusion welding, which makes the joint inseparable.

[0039] In the case of the metal seal surface sealing connection VCR®, the sealing is achieved when the seal is compressed by two flanges after tightening the male nut or the hexagonal head body part with the female nut. This principle allows a very good sealing with the possibility to use different seals (nickel, copper, stainless steel, ...) depending on the most suitable configuration, and easy fitting / unfitting with exchange of these seals during operation. However, this solution is not suitable at high temperatures and its operation allows a maximum temperature of only about 537 °C.

[0040] In the case of welded joints, the total seal is achieved by welding the tubes by a TIG (Tungsten Inert Gas) type method or by an orbital welder, i.e. a TIG method combined with a rotary nozzle. However, welding operations with the stack 20 mounted in the furnace 10 are very tedious due to the lack of access to allow the tubes to be welded circumferentially.

[0041] Finally, there are coupling systems that withstand temperatures of around 870 °C, which use sealing bushings of the partitions to pass sensors, probes, electrical signals and tubes. These sealing bushings of the partitions take the form of stainless steel 316L threaded connectors that are screwed into the wall of the pipe, vessel or cover. Depending on their version, these bushings accommodate one or several penetration elements, with different types, sizes and diameters. These bushings therefore allow the element to penetrate without interruption and also do not allow a sealing joint of both elements.

[0042] The coupling of the gas supply and exhaust devices in the cold parts PF of the furnace 10 is a major drawback, since these cold parts PF are not resistant to the furnace 10 and are hindered by peripheral equipment such as exchangers, insulators, condensers, among others. This means that priority should be given to making the joints in the hot parts PC if ease of coupling, disengagement and reuse is to be sought.

[0043] Additionally, using the furnace 10 enclosure to preheat the inlet gases also results in a loop tube 12 of approximately 2.5 to 3 m in length taking advantage of the radiation of the furnace 10 heating resistance, but this complicates the bending process to ensure the tube reaches the correct location within the confined space.

[0044] Furthermore, if it is desired to have the stack 20 detachable so that it can be operated in another location, thereby providing a "plug and play" (PnP) type feature, the joints must first be mechanically broken, for example using a hacksaw, and new joints must be prepared to place the stack 20 in another furnace, which would be a very cumbersome handling operation.

[0045] Finally, it should be noted that such a stack 20 is very fragile and needs to be repositioned with as little effort as possible, so vibrations and shocks should in particular be avoided, as should tipping.

[0046] The previously described coupling solutions do not meet the needs stated above. In particular, the dual ring mechanical crimp connectors are welded at high temperatures. Welding does not solve the described problems due to the complexity of the weld (difficult access) and the necessity to cut the tube for disconnection.

[0047] Prior art joining solutions do not allow the stack 20 to be removed from a furnace 10 and reconnected to another furnace 10, i.e., do not allow for a "plug and play" feature, without mechanically breaking the joints, and therefore subject the installation / uncoupling personnel to tedious bending, joining and mating operations. [Prior art documents] [Patent documents]

[0048] [Patent Document 1] French Patent Application No. FR3045215A1 [Patent Document 2] French Patent Application No. 1750009 Summary of the Invention [Problem to be solved by the invention]

[0049] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to at least partially overcome the above-mentioned needs and shortcomings of prior art embodiments.

[0050] In particular, the present invention is directed to the performance of a particular design of connection for high temperature electrolysis (SOEC) or fuel cell (SOFC) stacks, in particular stacks having a "plug and play" (PnP) type feature (self-crimping system) as described in French patent application no. FR 3 045 215 A1. [Means for solving the problem]

[0051] Thus, an object of the present invention, according to one of its aspects, is an assembly, - a solid oxide stack of the SOEC / SOFC type operating at high temperatures, 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 intermediate interconnectors each disposed between two adjacent electrochemical cells. and a SOEC / SOFC type solid oxide stack, - a compression system for a SOEC / SOFC type solid oxide stack, comprising an upper compression plate and a lower compression plate, between which the SOEC / SOFC type solid oxide stack is sandwiched, each compression plate comprising at least two compression holes, the compression system comprising: - at least two crimping rods for assembling the upper crimping plate and the lower crimping plate therebetween, each of which passes through a crimping hole of the upper crimping plate and a corresponding crimping hole of the lower crimping plate; - crimping means in each crimping hole of the upper and lower crimping plates cooperating with said at least two crimping rods to assemble the upper and lower crimping plates therebetween; a crimping system further comprising: - a high-temperature sealing connection system for connecting said SOEC / SOFC type solid oxide stack to a heating system, in particular a furnace, for gas supply and evacuation, which connection system is advantageously detachable and advantageously allows electrically insulating said SOEC / SOFC type solid oxide stack, The combined system is - a collector or manifold with at least two collection ducts for gas supply and discharge, each of which is provided with a collection hole located facing a corresponding communication hole in at least one of the upper and lower crimping plates; at least two seals (35) each disposed between a collection hole (33) and a corresponding communication hole (34); The assembly comprises:

[0052] The assembly according to the invention may further comprise one or more of the following characteristics, taken alone or in any technically possible combination:

[0053] Advantageously, the communication holes may belong to the lower crimp plate of the crimping system, which the invention can therefore advantageously use to quickly mount the stack on a collector in the system and meanwhile allow a sealed and detachable fluidic engagement.

[0054] In addition, advantageously, the seal makes it possible to ensure a seal between the stack equipped with an autonomous crimping system and the collector.The seal may in particular have a toric shape.

[0055] The coupling system is advantageously releasable and therefore reusable after temperature cycling, only the seal needs to be replaced after each detachment / reattachment.

[0056] The bonding system advantageously allows electrical isolation of the SOEC / SOFC type solid oxide stack with respect to the rest of the assembly, in particular the heating system, which is not possible with conventional prior art solutions of the double ring metal connector or VCR type.

[0057] The SOEC / SOFC type solid oxide stack can include an upper end plate and a lower end plate with a number of electrochemical cells and a number of intermediate interconnects sandwiched between the upper and lower end plates.

[0058] Preferably, the at least two seals may be made of mica. The use of mica seals has several advantages, which are detailed below. Firstly, it ensures a reliable seal of the gas supply and exhaust joints between the stack and the heating system, such as a furnace, for temperatures ranging from 0° C. to 900° C. The geometry of the seals may be optimized to ensure a compressive stress in the mica that is sufficient to ensure a robust seal. This stress depends on the thickness of the mica. Thus, for example, for a mica seal with a thickness of about 0.25 mm, the applied compressive stress may be at least 13 MPa.

[0059] In addition, the mica seal makes it possible to electrically insulate the stack with respect to the heating system.

[0060] Additionally, the mica seal allows the joint to be repeatedly disconnected / reconnected by avoiding the welding of hot metal flats as well as multiple temperature cycling.

[0061] The thickness of said at least two mica seals may preferably be less than or equal to 0.3 mm. Such a thickness value of the mica seals makes it possible to achieve both low-temperature and high-temperature sealing.

[0062] Alternatively, the at least two seals may be made from metal.

[0063] For example, the at least two seals may be bi-delta type O-ring seals having a substantially rectangular shaped cross-section, two opposing long sides of which each include a protruding annular portion of a substantially triangular shape, both protruding portions overlapping each other.

[0064] The at least two seals may further be C-ring type seals having a C-shaped cross section.

[0065] In addition, the collection holes of the at least two collection ducts of the collector can be positioned facing the corresponding communication holes of the lower crimping plate so that the stress applied to the at least two seals to join the sealing parts is exerted only by the weight of the stack equipped with the crimping system.

[0066] Furthermore, the collector may include at least one fastening through hole, through which a crimping rod of the crimping system may pass completely, and the coupling system may further include fastening means for fastening the collector to said at least one of the upper and lower crimping plates cooperating with the portion of the crimping rod that has passed through said at least one fastening hole.

[0067] The crimping rod may advantageously be threaded. Furthermore, the fixing means may be a fixing nut. The threaded crimping rod and / or the fixing nut may be coated with a high temperature anti-seize paste.

[0068] Additionally, the at least two collection ducts of the collector may each be coupled to the at least one of the upper and lower crimp plates through a sealed detachable connector.

[0069] The releasable sealed connector may be formed by a high temperature sealing bonding system; - a hollow base, integral with said at least one of the upper and lower crimping plates and at least partially threaded on its outer surface, called a threaded base, which is fixed to the internal communication duct of the stack, the threaded base including a communication hole; - a hollow base having an at least partially smooth outer surface, called the smooth base, integral with the collector and fixed to a collection duct of the collector, the smooth base including collection holes, the smooth base and the threaded base being positioned facing each other so as to be in fluid communication with each other; - a threaded nut capable of cooperating with the threaded base to form a screw / nut system and slidable relative to the smooth base, the threaded nut including on its inner surface a first threaded portion that cooperates with the threads of the threaded base and a second smooth portion in slidable contact with the smooth outer surface of the smooth base.

[0070] In addition, the smooth base, the threaded nut, and the threaded base may be made from a nickel-based superalloy, in particular Inconel 600, and / or an austenitic stainless steel, in particular stainless steel type 316L.

[0071] Yet another object of the present invention is, according to another of its aspects, a system, comprising: - Assemblies such as those already defined, a heating system, in particular an oven, which is coupled to said SOEC / SOFC type solid oxide stack of the assembly through a coupling system of the assembly for gas supply and exhaust; The system includes:

[0072] The assemblies and systems according to the invention may comprise any of the features mentioned in the description, either alone or in any technically possible combination with other features.

[0073] The invention will be better understood on reading the following detailed description of its non-limiting exemplary implementations, as well as on examining the schematic and partial views of the accompanying drawings, in which: [Brief description of the drawings]

[0074] [Figure 1] FIG. 1 is a schematic diagram illustrating the theory of operation of a high temperature solid oxide electrolyzer (SOEC). [Diagram 2] FIG. 1 is an exploded schematic diagram of a portion of a high temperature solid oxide electrolyzer (SOEC) with an interconnect according to the prior art. [Diagram 3] FIG. 1 illustrates the principle of the architecture of a reactor in which a high temperature electrolysis (SOEC) or fuel cell (SOFC) stack operating at high temperatures is placed. [Figure 4] FIG. 1 is a perspective view of an example of a SOEC / SOFC type solid oxide stack for an assembly according to the invention, together with its bonding system. [Figure 5A] FIG. 1 is a side assembly view of a first exemplary embodiment of an assembly according to the present invention. [Figure 5B] 1 is a partial cross-sectional view of a first exemplary embodiment of an assembly according to the present invention; [Figure 5C] FIG. 1 is an exploded perspective view of a first exemplary embodiment of an assembly according to the present invention. [Figure 6A] FIG. 2 is a side assembly view of a second exemplary embodiment of an assembly according to the present invention. [Figure 6B] FIG. 4 is a partial cross-sectional view of a second exemplary embodiment of an assembly according to the present invention. [Figure 6C] FIG. 2 is an exploded perspective view of a second exemplary embodiment of an assembly according to the present invention. [Figure 7A]FIG. 13 is a side assembly view of a third exemplary embodiment of an assembly according to the present invention. [Figure 7B] FIG. 11 is a partial cross-sectional view of a third exemplary embodiment of an assembly according to the present invention. [Figure 7C] FIG. 13 is an exploded perspective view of a third exemplary embodiment of an assembly according to the present invention. [Figure 8A] FIG. 1 is a perspective view of a first alternative form of seal for an assembly according to the present invention; [Figure 8B] FIG. 2 is a partial cross-sectional view showing a first alternative form of seal for an assembly according to the present invention; [Figure 9] 11A and 11B are perspective and partial cross-sectional views of a second alternative form of seal for an assembly according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] Throughout the figures, the same reference numbers may designate the same or similar elements.

[0076] Furthermore, the various parts represented in the figures are not necessarily drawn to the same scale in order to make the figures easier to read.

[0077] Figures 1 to 3 have already been described in the section relating to the prior art and technical background of the present invention. With respect to Figures 1 and 2, it is stated that the symbols and arrows for the supply of water vapor H2O, dihydrogen H2, oxygen O2, air, and distribution and recovery of electric current are shown for clarity, accuracy, and to illustrate the operation of the device represented.

[0078] Furthermore, it should be noted that all components (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramic. The operating temperatures of high temperature SOEC / SOFC type stacks are additionally typically between 600 and 1000° C.

[0079] Furthermore, the optional terms "upper" and "lower" herein must be understood along the normal orientation of an SOEC / SOFC type stack.

[0080] Referring to FIG. 4, an exemplary assembly 80 is illustrated comprising an SOEC / SOFC type solid oxide stack 20 and a bonding system 60, which may be integrated into an assembly 100 according to the present invention as described below with reference to FIGS. 5A-5C, 6A-6C, and 7A-7C.

[0081] Advantageously, the assembly 80 has a structure similar to that of the assembly described in French patent application FR 3 045 215 A1, ie the stack 20 has a "Plug & Play" (PnP) type feature.

[0082] Also in common with the different embodiments of the invention described below, as can be seen in FIG. 4, the assembly 80 comprises an SOEC / SOFC type solid oxide stack 20 operating at high temperatures.

[0083] The stack 20 comprises a number of electrochemical cells 41, each formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a number of intermediate interconnects 42, each disposed between two adjacent electrochemical cells 41. This assembly of electrochemical cells 41 and intermediate interconnects 42 may also be referred to as a "stack."

[0084] Further, the stack 20 comprises an upper end plate 43 and a lower end plate 44, also referred to as the upper stack end plate 43 and the lower stack end plate 44, respectively, between which the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42 are sandwiched, i.e., there is a stack between them.

[0085] Additionally, the assembly 80 also includes a compression system 60 for the SOEC / SOFC type solid oxide stack 20, comprising an upper compression plate 45 and a lower compression plate 46, between which the SOEC / SOFC type solid oxide stack 20 is sandwiched.

[0086] Each crimp plate 45 , 46 of the crimping system 60 includes four crimp holes 54 .

[0087] Additionally, the crimping system 60 further comprises four crimping rods 55, i.e. tie rods, which pass through the crimping holes 54 in the upper crimping plate 45 and through corresponding crimping holes 54 in the lower crimping plate 46, enabling the upper crimping plate 45 and the lower crimping plate 46 to be assembled to one another.

[0088] The crimping system 60 further comprises crimping means 56, 57, 58 at each crimping hole 54 of the upper and lower crimping plates 45, 46 which cooperate with the crimping rod 55 to assemble the upper and lower crimping plates 45, 46 together.

[0089] More precisely, the crimping means comprise, at each crimping hole 54 of the upper crimping plate 45, a first crimping nut 56 cooperating with a corresponding crimping rod 55 inserted through the crimping hole 54. Furthermore, the crimping means comprise, at each crimping hole 54 of the lower crimping plate 46, a second crimping nut 57 associated with a crimping washer 58 cooperating with a corresponding crimping rod 55 inserted through the crimping hole 54. The crimping washer 58 is arranged between the second crimping nut 57 and the lower crimping plate 46.

[0090] The assembly 100 according to the invention additionally comprises a high-temperature sealing coupling system 30 for the stack 20 for the gas supply and exhaust between the stack 20 and the heating system, in particular the furnace 10, as previously explained. In figures 5A to 7C different possibilities for the coupling system 30 can be illustrated.

[0091] Thus, according to the invention, in a manner common to all embodiments of the invention, the high temperature sealing connection system 30 for the stack 20 comprises a collector 31, or also called a manifold, which comprises four collection ducts 32 for gas supply and discharge. Each collection duct 32 comprises a collection hole 33 opening in the surface of the collector 31 facing the lower crimp plate 46.

[0092] In addition, the lower crimping plate 46 of the autonomous crimping system 60 of the stack 20 comprises communication holes 34 for the internal communication ducts 37 of the stack 20, as can be seen, for example, in Figures 5B, 6B and 7B.

[0093] Advantageously, the collection hole 33 is located facing the communication hole 34 to allow fluid connection between the stack 20 and the collector 31 for gas supply and exhaust.

[0094] Additionally, a seal 35 is advantageously placed between each collection hole 33 and its corresponding communication hole 34 to ensure a sealed bond.

[0095] 5A, 5B, and 5C respectively depict a side assembly view, a partial cross-sectional view, and an exploded perspective view of a first exemplary embodiment of an assembly 100 according to the present invention.

[0096] In this first example, the collection hole 33 of the collection duct 32 of the collector 31 is positioned facing the corresponding communication hole 34 of the lower crimping plate 46 so that the stress applied to the seal 35 for joint sealing is exerted only by the weight of the stack 20 equipped with the autonomous crimping system 60.

[0097] In other words, only the weight of the stack 20 and its autonomous crimping system 60 is used to ensure a seal at the seal 35 .

[0098] Advantageously, therefore, removal and placement of the stack 20 within the system can be easily performed, in particular by simply changing the seals 35, in particular the mica seals which are then consumable, thus ensuring that the seal between the stack 20 and the system is adequate.

[0099] In this first exemplary embodiment, only the own weight of the stack 20 equipped with the autonomous crimping system 60 is used to ensure sealing of the gas supply and exhaust connections between the stack 20 and the furnace 10, i.e. to apply a stress determined as a function of the material thickness of the seal 35, in particular the mica seal, the contact surface area, and the weight of the stack 20 equipped with the crimping system 60.

[0100] However, the weight of the stack 20 exerts the necessary stress on the seal 35 to provide an adequate seal at high temperatures, i.e., especially at 2.10 -5 P.A.M. 3 .s -1 If this is not sufficient to ensure a lower measured leakage, an alternative coupling may be provided according to the next described embodiment.

[0101] 6A, 6B, and 6C depict a side assembly view, a partial cross-sectional view, and an exploded perspective view, respectively, of a second exemplary embodiment of an assembly 100 according to the present invention.

[0102] In this second embodiment, the tie rods or crimping rods 55 of the autonomous crimping system 60 are advantageously used to allow the coupling, in particular the total screwing, to be performed. They can therefore be used to apply an additional load to the seal 35, which is controlled through a determined crimping torque applied to the fixing nut 38.

[0103] More precisely, as can be seen best in FIG. 6C, the collector 31 comprises four fixed through-holes 70 into which the four crimping rods 55 of the crimping system 60 are inserted.

[0104] Additionally, four fixing nuts 38 are used and threaded onto the four crimp rods 55 to assemble the collector 31 onto the lower crimp plate 46 .

[0105] Advantageously, an electrically insulating element (not shown), such as a mica or ceramic element, can be inserted between the fixing nut 38, the crimping rod 55 and the collector 31 to restore the load on the crimping rod 55 and maintain electrical insulation of the stack 20 with respect to the system.

[0106] Also advantageously, the threads of the crimping rod 55 and / or the fixing nut 38 can be coated with a high temperature anti-seize paste prior to placing and crimping the collector 31 on the crimping rod 55, which can facilitate engagement and disengagement and avoid diffusion welding of the threads.

[0107] This anti-seize paste can be a corrosion-resistant high-temperature assembly lubricating anti-seize paste, making it possible to avoid overblocking and wear of parts exposed to extremely high temperatures or highly corrosive atmospheres, such as, among others, threads of heat engines, manifolds for hot gases, burners, valves, disc brakes, spark plugs, exhaust fasteners, rollers, bolts, collars, etc. It can have a formulation based on copper, aluminum and graphite to protect metal parts and ensure their engagement and disengagement. It can be, for example, the green grease sold by Pyrox Thermique Materiaux, consisting of a mixture of 50% chromium powder 3 and copper grease for machine parts sold by Wurth Company.

[0108] Additionally, Figures 7A, 7B, and 7C respectively depict a side assembly view, a partial cross-sectional view, and an exploded perspective view of a third exemplary embodiment of an assembly 100 according to the present invention.

[0109] In this third example, the four collection ducts 32 of the collector 31 are connected to the lower crimping plate 46 of the crimping system 60 through detachable sealed connectors 90. Such connectors are described in particular in French patent application no. 17 50009.

[0110] More precisely, each sealed detachable connector 90 is formed by a high-temperature sealing joint system which firstly comprises a hollow base 91, partially threaded on its outer surface, called threaded base, which is integral with the lower crimp plate 46 and which is fixed to the internal communication duct 37 of the stack 20. Furthermore, the threaded base 91 comprises a communication hole 34 as previously described.

[0111] Furthermore, the system also comprises a hollow base 92 with a smooth outer surface, called smooth base, which is integrated with the collector 31 and fixed to the collection duct 32 of the collector 31. Furthermore, the smooth base 92 comprises the collection holes 33 as previously described.

[0112] Thus, the smooth base 92 and the threaded base 91 are positioned facing each other so as to be in fluid communication with each other.

[0113] Finally, the system comprises a threaded nut 93 which can cooperate with the threaded base 91 to form a screw / nut system and which can slide relative to the smooth base 92. As can be seen in Figure 7B, the threaded nut 93 comprises on its inner surface a first threaded portion 93a which cooperates with the threads of the threaded base 91 and a second smooth portion 93b which is in slidable contact with the smooth outer surface of the smooth base 92.

[0114] Advantageously, the smooth base 92, the threaded nut 93 and the threaded base 91 may be made from a nickel-based superalloy, in particular of the Inconel 600 type, and / or from an austenitic stainless steel, in particular of the stainless steel 316L type.

[0115] The threaded base 91 may be fastened by welding or machining into the lower crimp plate 46 of the crimp system 60 when manufactured so as to be part of the assembly 80 including the stack 20 and the crimp system 60 .

[0116] The threaded nut 93 may then advantageously be integral with the collector 31 and may be a bearing plane for the stack 20 through the smooth base 92. The threaded nut 93 is slidably mounted on the smooth base 92 with play.

[0117] The smooth base 92 may then be secured to the collector 31 by welding.

[0118] It is thus possible to obtain a plane / plane type contact between the smooth base 92 of the collector 31 and the threaded base 91 of the lower crimping plate 46, with the seal 35 being inserted between both bases 91 and 92 to ensure sealing of the screw / nut connection. It is thus the screw / nut crimping torque that makes it possible to ensure the necessary stress for sealing on the seal 35.

[0119] If necessary, a second seal 35 , in particular a second mica washer, can be inserted between the threaded nut 93 and the smooth base 92 to ensure electrical insulation of the stack 20 .

[0120] The nominal diameter of the threaded nut 93 may be between M20 and M30. In fact, the thick threads and the significant pitch may make it possible to avoid diffusion welding between the threads.

[0121] In addition, the threaded base 91 may have a height between 15 and 30 mm, and a diameter between 20 and 30 mm.

[0122] Additionally, the smooth base 92 may have a height of between 45 and 70 mm, and a maximum diameter of 30 mm.

[0123] The first threaded portion 93a of the threaded nut 93 and / or the threads of the threaded base 91 may further be covered with a high temperature resistant anti-seize agent, which may be such as the anti-seize paste previously described for coating the threads of the crimp rod 55 and / or the fixing nut 38.

[0124] In all of the previously described examples, the seal 35 is preferably made of mica.

[0125] However, it is also possible to provide the seal 35 made from another material, for example a metal O-ring seal.

[0126] Figures 8A and 8B also illustrate the possibility of having, for example, a bi-delta type O-ring seal 35. As can be seen in Figure 8B, this bi-delta type seal is characterized by having a substantially rectangular shaped cross section, with both long sides of the rectangular shaped cross section each including a protruding annular portion 35a of a substantially triangular shape. Furthermore, these two protruding portions 35 are overlapped with each other.

[0127] FIG. 9 additionally illustrates the possibility of having an O-ring seal 35 in the form of a C-ring type seal, ie having a C-shaped cross section.

[0128] Of course, the invention is not limited to the merely described exemplary embodiment, various modifications being possible for those skilled in the art. [Explanation of symbols]

[0129] C1, C2 Basic electrolytic cells 1 Basic electrolysis cell 2 cathode 2.1, 2.2 Cathode 3 Solid electrolyte 3.2 Electrolytes 4 Anode 4.2 Anode 5 Interconnector 10 furnace 11 Hearth bottom 12 Loop Tube 20 SOEC / SOFC type solid oxide stack 30 High Temperature Sealing and Bonding Systems 31 Collector 32 Collection duct 33 Collection hole 34 Communication hole 35 Seal 35a a protruding annular portion of substantially triangular shape 37 Internal communication duct 38 Fixing nut 41 Electrochemical Cell 42 Intermediate Interconnector 43 Upper stack end plate 44 Lower stack end plate 45 Upper crimp plate 46 Lower pressure plate 50 cathode 51 Anode 54 Crimp Hole 55 Crimping Rod 56, 57, 58 Crimping means 56 First crimp nut 57 Second crimp nut 58 Crimp washer 60 Crimping System 70 fixed through hole 80 Assembly 90 Detachable sealed connector 91 Hollow base, threaded base 92 Hollow base, smooth base 93 Threaded Nut 93a First Threaded Part 93b Second smooth part 100 Assembly

Claims

1. An assembly (100), comprising: A solid oxide stack (20) of the SOEC / SOFC type operating at high temperatures, a solid oxide stack (20) of the SOEC / SOFC type, comprising a number of electrochemical cells (41), each formed by a cathode, an anode and an electrolyte interposed between said cathode and said anode, a number of intermediate interconnects (42) each arranged between two adjacent electrochemical cells (41), an upper end plate and a lower end plate, between which said electrochemical cells and said intermediate interconnects are sandwiched; a compression system (60) for said SOEC / SOFC type solid oxide stack (20), comprising an upper compression plate (45) and a lower compression plate (46), between which said SOEC / SOFC type solid oxide stack (20) is sandwiched, each compression plate (45, 46) comprising at least two compression holes (54), said compression system (60) comprising: at least two crimping rods (55) for assembling said upper crimping plate (45) and said lower crimping plate (46) relative to one another, each passing through a crimping hole (54) in said upper crimping plate (45) and a corresponding crimping hole (54) in said lower crimping plate (46); - crimping means (56, 57, 58) in each crimping hole (54) of said upper crimping plate (45) and said lower crimping plate (46) cooperating with said at least two crimping rods (55) for assembling said upper crimping plate (45) and said lower crimping plate (46) therebetween; a crimping system (60) further comprising: a high temperature sealing bonding system (30) for bonding said SOEC / SOFC type solid oxide stack (20) equipped with said bonding system (60) for gas supply and exhaust to a heating system (10), said bonding system (30) being engageable and disengageable with respect to said lower bonding plate (46) and making it possible to electrically insulate said SOEC / SOFC type solid oxide stack (20); An assembly (100) comprising: The SOEC / SOFC type solid oxide stack (20) equipped with the bonding system (60), wherein the upper bonding plate (45) of the bonding system (60) is in contact with the upper end plate of the SOEC / SOFC type solid oxide stack (20) and the lower bonding plate (46) of the bonding system (60) is in contact with the lower end plate of the SOEC / SOFC type solid oxide stack (20); The coupling system (30) comprises: a collector (31) comprising at least two collection ducts (32) for gas supply and evacuation, each of which is provided with a collection hole (33) located facing a corresponding communication hole (34) of said lower crimping plate (46); at least two seals (35) each placed between a collection hole (33) and a corresponding communication hole (34); 1. An assembly (100), comprising:

2. Assembly according to claim 1, characterized in that said at least two seals (35) are made from mica.

3. 3. An assembly according to claim 2, characterized in that the thickness of said at least two mica seals (35) is less than or equal to 0.3 mm.

4. 4. The assembly according to claim 1, characterized in that the collection holes (33) of the at least two collection ducts (32) of the collector (31) are located facing the corresponding communication holes (34) of the lower compression plate (46) in such a way that the stress applied to the at least two seals (35) for joining the seals is exerted only by the weight of the SOEC / SOFC type solid oxide stack (20) equipped with the compression system (60).

5. 4. An assembly according to claim 1, characterized in that the collector (31) comprises at least one fastening through-hole (70) through which a crimping rod (55) of the crimping system (60) can completely pass, and in that the connecting system (30) comprises fastening means (38) for fastening the collector (31) to the lower crimping plate (46) which cooperate with the part of the crimping rod (55) that has passed through the at least one fastening through-hole (70).

6. 6. An assembly according to claim 5, characterized in that said crimping rod (55) is threaded and said fastening means (38) is a fastening nut.

7. 7. An assembly according to claim 6, characterized in that the threaded crimp rod (55) and / or the fixing nut (38) are coated with a high-temperature anti-seize paste.

8. 8. An assembly according to claim 1, wherein the at least two collecting ducts (32) of the collector (31) are each coupled to the lower crimp plate (46) through a sealed detachable connector (90).

9. The sealed detachable connector (90) is formed by a high temperature sealing bonding system, the system comprising: a hollow base (91) at least partially threaded on its outer surface, called a threaded base, integral with said lower crimp plate (46) and fixed to the internal communication duct (37) of said stack (20), said threaded base (91) including a communication hole (34); a hollow base (92) having an at least partially smooth outer surface, called the smooth base, integral with said collector (31) and fixed to the collection duct (32) of said collector (31), said smooth base (92) comprising collection holes (33), said smooth base (92) and said threaded base (91) being placed facing each other so as to be in fluid communication with each other; a threaded nut (93) capable of cooperating with said threaded base (91) to form a screw / nut system and capable of sliding with respect to said smooth base (92), said threaded nut (93) comprising on its inner surface a first threaded portion (93a) which cooperates with said threads of said threaded base (91) and a second smooth portion (93b) which is in slidable contact with the smooth outer surface of said smooth base (92); 9. The assembly of claim 8, comprising:

10. 10. The assembly according to claim 9, characterized in that the smooth base (92), the threaded nut (93) and the threaded base (91) are made from a nickel-based superalloy and / or an austenitic stainless steel.

11. 1. A system comprising: - an assembly (100) according to any one of claims 1 to 10, a heating system (10) coupled to said SOEC / SOFC type solid oxide stack (20) of said assembly (100) through said coupling system (30) of said assembly (100) for gas supply and exhaust; A system comprising:

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