An assembly comprising a stack of SOEC / SOFC type solid oxide cells and a clamping system with a heating plate

Abstract

The main subject of the invention is an assembly (80) including a stack of solid oxide cells of the SOEC / SOFC type and a clamping system for the stack, said assembly (80) further including at least one heating plate (95) that is removable and replaceable and is inserted in a housing (90) of at least one of the upper clamping plate (45) and the lower clamping plate (46), said housing (90) being sized to fit within the thickness (e p ) and include first and second opposite ends, at least one of the first and second ends emerging on a lateral face (FL) of said at least one of the top clamping plate (45) and bottom clamping plate (46) and positioned substantially parallel to and inwardly of each other at a predetermined distance from the main top (FS) and bottom (FI) faces thereof.

Description

Technical Field

[0001] The present invention relates to the general field of high temperature electrolysis (HTE), particularly high temperature steam electrolysis (HTSE) (each denoted by the English terms "High Temperature Electrolysis" (THE) and "High Temperature Steam Electrolysis" (HTSE)), carbon dioxide (CO 2 ) electrolysis, or even high temperature steam and carbon dioxide (CO 2 ) co-electrolysis.

[0002] More precisely, the present invention relates to the field of high temperature solid oxide electrolysis cells (usually denoted by the acronym SOEC, which is short for "Solid Oxide Electrolysis Cell" in English).

[0003] The present invention also relates to the field of high temperature solid oxide fuel cells (usually denoted by the acronym SOFC, which is short for "Solid Oxide Fuel Cells" in English).

[0004] Thus, more generally, the present invention refers to the field of SOEC / SOFC type solid oxide stacks operating at high temperatures.

[0005] More precisely, the present invention relates to an assembly comprising a stack of SOEC / SOFC type solid oxide cells and a clamping system including at least one removable and replaceable heating plate, as well as related manufacturing methods.

Background Art

[0006] In the context of high temperature solid oxide electrolysis cells of the SOEC type, it is a single same electrochemical device in which, by means of an electric current, steam (H 2 O) is converted into hydrogen (H 2 ) and dioxygen (O2 ) to carbon dioxide (O 2 ) is converted to carbon monoxide (CO) and dioxygen (O 2 ). In the context of a SOFC type high temperature solid oxide fuel cell, the operation is reversed, and hydrogen (H 2 ) or other fuels (e.g., methane (CH 4 ), natural gas, or biogas, etc.), and dioxygen (O 2 )(typically air) are supplied while generating an electric current and heat. For reasons of brevity, the following description specifically addresses the operation of a SOEC type high temperature solid oxide electrolyzer that performs the electrolysis of steam. However, this operation is applicable to the electrolysis of carbon dioxide (CO 2 ), or even more so to the co - electrolysis of high temperature steam and carbon dioxide (CO 2 ). In addition, this operation is convertible to the case of a SOFC type high temperature solid oxide fuel cell.

[0007] To perform the electrolysis of water, it is advantageous to perform it at a high temperature (typically between 600 °C and 1000 °C). The reason is that it is more advantageous to electrolyze steam rather than liquid water, and also because some 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), a SOEC-type high-temperature solid oxide electrolyzer is composed of a basic pattern stack, where the basic pattern includes a solid oxide electrolysis cell (or an electrochemical cell), which is composed of three anode / electrolyte / cathode layers stacked on top of each other, and an interconnecting plate made of a metal alloy (also referred to as a bipolar plate or an interconnector). Each electrochemical cell is sandwiched between two interconnecting plates. Then, the SOEC-type high-temperature solid oxide electrolyzer is an alternating stack of electrochemical cells and interconnectors. A SOFC-type high-temperature solid oxide fuel cell is composed of a stack of the same type of basic pattern. Since this high-temperature technology is reversible, the same stack can operate in the electrolysis mode to produce hydrogen and oxygen from water and electricity, or operate in the fuel cell mode to produce electricity from hydrogen and oxygen.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a multilayer assembly made of ceramic, whose electrolyte is formed by an ion-conductive central layer, which is solid, dense, and impermeable, and is sandwiched between two porous layers that form the electrodes. It should be noted that additional layers may be present, but only serve to improve one or more of the layers already described.

[0010] The interconnect device (electrical and fluid interconnect device) is an electronic conductor which, from an electrical point of view, provides the connection of each electrochemical cell in a stack of basic patterns, ensuring the electrical contact between one side and the cathode of the cell and the electrical contact between the other side and the anode of the next cell, and which, from a fluid point of view, provides the supply of reagents and the release of products for each of the cells. Thus, the interconnector fulfills the function of bringing in and collecting the current and also fulfills the function of defining the boundaries of the gas circulation compartments for distribution and / or collection.

[0011] More precisely, the main function of the interconnector is to provide for the passage of the current but also to provide for the circulation of the gas in the vicinity of each cell (i.e., the vapor injected and the hydrogen and oxygen extracted for EHT electrolysis; the air and the fuel (including the hydrogen injected and the water extracted for the SOFC cell)), and also to separate the anode compartment and the cathode compartment of two adjacent cells (which are, respectively, the compartments for the circulation of the gas on the anode side and the cathode side of the cell).

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

[0013] To carry out high-temperature steam electrolysis (HTSE), steam (H 2 O) is injected into the cathode compartment. Under the effect of the current applied to the cell, the dissociation of the water molecules in the form of steam is carried out at the interface between the hydrogen electrode (cathode) and the electrolyte. This dissociation results in dihydrogen gas (H 2 ) and oxygen ions (O2- ) generates. Dihydrogen (H 2 ) is collected and released at the outlet of the hydrogen compartment. Oxygen ions (O 2- ) migrate through the electrolyte and recombine as dioxygen (O 2 ) at the interface between the electrolyte and the oxygen electrode (anode). The purge gas (e.g., air, etc.) circulates at the anode and can thus collect the oxygen generated in gaseous form at the anode.

[0014] To operate 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. The oxygen in the air dissociates into O 2- ions. These ions migrate through the cathode electrolyte to the anode, oxidize hydrogen, and form water with the simultaneous generation of electricity. In an SOFC cell, just as in SOEC electrolysis, steam is in the dihydrogen (H 2 ) compartment. Only the polarity is reversed.

[0015] As shown in the figure, Figure 1 is a schematic diagram showing the operating principle of an SOEC-type high-temperature solid oxide electrolyzer. The function of such an electrolyzer is to convert steam into hydrogen and oxygen according to the following electrochemical reaction. 2H 2 O → 2H 2 + O 2 .

[0016] This reaction is carried out electrochemically in the cells of the electrolyzer. As schematically shown in Figure 1, each basic electrolysis cell 1 is formed by a cathode 2 and an anode 4, and the cathode 2 and the anode 4 are installed on either side of a solid electrolyte 3. The two electrodes (cathode and anode) 2 and 4 are electron and / or ion conductors made of a porous material, and the electrolyte 3 is airtight, electronically insulating, and ion conductive. The electrolyte 3 can, inter alia, be an anion conductor, or rather, can be an anion conductor for O 2- ions, and the electrolyzer is then called an ionic electrolyzer as opposed to a proton electrolyte (H + +).

[0017] The electrochemical reaction takes place at the interface between each of the electron conductors and the anion conductor.

[0018] At the cathode 2, the half-reaction is as follows. 2H 2 2O + 4e - → 2H 2 2O + 2O 2- .

[0019] At the anode 4, the half-reaction is as follows. 2O 2- → O 2 2 + 4e - .

[0020] The electrolyte 3 (interposed between the two electrodes 2 and 4) is the site of the migration of O 2- ions under the influence of the electric field created by the potential difference imposed between the anode 4 and the cathode 2.

[0021] As shown between the brackets in Figure 1, the vapor at the cathode inlet is hydrogen H 2It can be entrained by [the relevant factor], and the hydrogen generated and recovered at the outlet can be entrained by steam. Similarly, as shown by the dashed line, a purge gas (such as air, etc.) can be further injected at the inlet on the anode side to release the generated oxygen. The additional function of injecting the purge gas is to act as a temperature regulator.

[0022] A basic electrolyzer or electrolysis reactor is composed of a basic cell as described above with a cathode 2, an electrolyte 3, and an anode 4, and two interconnects that perform electrical and fluid distribution functions.

[0023] To increase the flow rates of the generated hydrogen and oxygen, it is known to stack a plurality of basic electrolysis cells on top of each other and separate them by interconnects. The assembly is positioned between two end interconnect plates that support the electrical supply and gas supply of the electrolyzer (electrolysis reactor).

[0024] Therefore, a SOEC - type high - temperature solid oxide electrolyzer includes at least one, generally a plurality of, electrolysis cells stacked on top of each other. Each basic cell is formed by an electrolyte, a cathode, and an anode, and the electrolyte is interposed between the anode and the cathode.

[0025] As previously shown, a fluid and electrical interconnect device in electrical contact with one or more electrodes generally serves the function of bringing in and collecting current and defines the boundaries of one or more gas circulation compartments.

[0026] Therefore, the function of the so - called cathode compartment is the distribution of current and steam and the recovery of hydrogen at the contacting cathode.

[0027] The so-called function of the anode compartment is the distribution of current and the recovery of oxygen generated at the contacting anode, optionally by a purge gas.

[0028] Figure 2 shows an exploded view of the basic pattern of a prior art SOEC type high-temperature solid oxide electrolyzer cell. This electrolyzer cell includes a plurality of basic electrolysis cells C1, C2 of the solid oxide cell (SOEC) type stacked alternately together with an interconnector 5. Each cell C1, C2 is composed of cathodes 2.1, 2.2 and anodes (only the anode 4.2 of cell C2 is shown), and an electrolyte is disposed therebetween (only the electrolyte 3.2 of cell C2 is shown).

[0029] The interconnector 5 is a component made of a metal alloy, which provides a separation between the cathode compartment 50 and the anode compartment 51, and the cathode compartment 50 and the anode compartment 51 are each defined by the volume included between the interconnector 5 and the adjacent cathode 2.1, and the volume included between the interconnector 5 and the adjacent anode 4.2. Also, it provides the distribution of gas to the cells. The injection of steam into each basic pattern is carried out in the cathode compartment 50. The hydrogen and residual steam generated at the cathodes 2.1, 2.2 are collected in the cathode compartment 50 downstream of the cells C1, C2 after the dissociation of steam by the cells C1, C2. The oxygen generated at the anode 4.2 is collected in the anode compartment 51 downstream of the cells C1, C2 after the dissociation of steam by the cells C1, C2. The interconnector 5 provides the passage of current between the cells C1 and C2 by direct contact with the adjacent electrodes, that is, between the anode 4.2 and the cathode 2.1.

[0030] The operating conditions of a high-temperature solid oxide electrolyzer cell (SOEC) are very similar to those of a solid oxide fuel cell (SOFC), and the same technical constraints are found.

[0031] Therefore, the correct operation of such a solid oxide stack of the SOEC / SOFC type operating at high temperature must mainly meet the points described below.

[0032] First, it is necessary to have electrical insulation between two consecutive interconnects (otherwise, the electrochemical cell will short-circuit), but it is also necessary to have good electrical contact and sufficient contact surface between the cell and the interconnect. As low an ohmic resistance as possible is required between the cell and the interconnect.

[0033] Furthermore, it is necessary to have airtightness between the anode compartment and the cathode compartment; otherwise, there will be recombination of the generated gas, causing a drop in efficiency and, in particular, the appearance of hot spots that damage the stack.

[0034] Finally, it is essential to have good gas distribution in both the input and the recovery of the products; otherwise, there will be losses in efficiency, pressure and temperature inhomogeneities in various basic patterns, or even unacceptable degradation of the electrochemical cell.

[0035] Conventionally, the incoming and outgoing gases in a high-temperature electrolysis (SOEC) or fuel cell (SOFC) stack operating at high temperature can be managed by a device such as that illustrated with reference to Figure 3, for example. Therefore, device 13 includes a low-temperature part PF and a high-temperature part PC, and the high-temperature part PC includes a furnace floor 11, a furnace bell 10, a loop tube 12 for managing the entry and exit of the gas, and a high-temperature electrolysis (SOEC) or fuel cell (SOFC) stack 20.

[0036] From French patent application FR3045215A1, the principle of a self - contained clamping system for a stack of the SOEC / SOFC type is known for making it self - contained and for imparting to it "plug & play" (PnP) type characteristics. Such a stack concept (having a removable integrated heating element (for example, of the electrical element type)) allows both applying a force to the manufacture of the stack, maintaining the same force including during operation at high temperature, and supplying the heat necessary for its operation as close as possible to the stack. This PnP system with an integrated heating unit allows for the rapid installation of the stack in a so - called "hot box" system (which then consists only of a compact insulated chamber), and also allows its operation without the need to manage its clamping during operation at high temperature, despite the expansion differences of the various components, allowing for an improvement in the thermal efficiency of the system and, consequently, its performance. Also, this makes it possible to obtain compactness in the heating zone since a resistance furnace is no longer necessary.

[0037] Referring to FIG. 4, an example of an assembly 80 is thus illustrated, which includes a solid oxide stack 20 of the SOEC / SOFC type and a clamping system 60. This stack 20 includes a plurality of electrochemical cells 41 each formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects 42 respectively disposed between two adjacent electrochemical cells 41. This assembly of electrochemical cells 41 and intermediate interconnects 42 is also referred to as a stack.

[0038] In addition, stack 20 includes upper end plate 43 and bottom end plate 44, which are also referred to as upper stack end plate 43 and bottom stack end plate 44 respectively. A plurality of electrochemical cells 41 and a plurality of intermediate interconnects 42 are clamped between upper stack end plate 43 and bottom stack end plate 44, i.e., the stack is positioned therebetween.

[0039] Furthermore, assembly 80 also includes a system 60 for clamping solid oxide stack 20 of the SOEC / SOFC type, which includes upper clamping plate 45 and bottom clamping plate 46. The solid oxide stack 20 of the SOEC / SOFC type is clamped between upper clamping plate 45 and bottom clamping plate 46. Each clamping plate 45, 46 of the clamping system 60 includes four clamping orifices 54.

[0040] In addition, clamping system 60 further includes four clamping rods 55 (or tie rods). The four clamping rods 55 extend through the clamping orifices 54 of upper clamping plate 45 and through the corresponding clamping orifices 54 of bottom clamping plate 46 in order to enable upper clamping plate 45 and bottom clamping plate 46 to be assembled together.

[0041] Also, clamping system 60 includes clamping means 56, 57, 58 at the respective clamping orifices 54 of upper clamping plate 45 and bottom clamping plate 46 that cooperate with clamping rods 55 in order to enable upper clamping plate 4 and bottom clamping plate 46 to be assembled together.

[0042] More precisely, the clamping means includes a first clamping nut 56 that cooperates with a corresponding clamping rod 55 inserted through the clamping orifice 54 at each clamping orifice 54 of the upper clamping plate 45. In addition, the clamping means includes a second clamping nut 57 associated with a clamping washer 58 at each clamping orifice 54 of the upper clamping plate 46, and the clamping washer 58 cooperates with a corresponding clamping rod 55 inserted through the clamping orifice 54. The clamping washer 58 is positioned between the second clamping nut 57 and the bottom clamping plate 46.

[0043] Furthermore, from French Patent Application FR3087952A1, the principle of integration of a heating element with an upper plate and a bottom plate of a self - contained clamping system of a PnP - type stack is also known, among other things, as described above. Thus, a heating - wire - type heating element is integrated into two upper clamping plates and a bottom clamping plate by machining and brazing, and the two upper clamping plates and the bottom clamping plate are on the order of 30 mm thick and are made of a refractory austenitic steel of the AISI310 type.

[0044] A heating element integrated within a high-density metallic component in direct contact with a stack thus significantly improves losses due to heat transfer, which then occurs by unperturbed conduction and uniformly across the contact zone. This results in excellent thermal homogeneity between the upper and lower plates, and thus good overall homogeneity of the stack, and an increased responsiveness of the heating element to a fixed temperature setting for the electrolyser. In this way, better overall thermal management of the system is obtained. Since the heating is integrated, the insulation can be modulated to fit the form of the stack and, furthermore, it is possible to limit the radiation to the outside. The effectiveness of the heat transfer of such a heating element then makes it possible to reduce the power supplied to the system by at least 100 W, to operate at temperatures on the order of 600 °C to 1000 °C. The temperature measured within the insulated chamber follows almost the same ramp-up as that of the plate, which is also a very good sign for the thermal control of the hot box.

[0045] However, one of the problems associated with this technology is the fact that there is no margin for manoeuvre in the event of a failure of the heating element. The heat management of the stack then is lost without the possibility of recovery. Furthermore, the cost of producing these heating elements (in the form of elements brazed, in particular, onto the clamping plates) is very high and thus restrictive.

[0046] Therefore, there remains a need to improve the integration of heating units in high-temperature electrolysis (SOEC) or fuel cell (SOFC) stacks while enabling operation at high temperatures (in particular, between 600 °C and 1000 °C).

Prior Art Documents

Patent Documents

[0047]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0048] The object of the present invention is to at least partially improve the above-mentioned requirements and the drawbacks related to the embodiments of the prior art.

Means for Solving the Problems

[0049] The object of the present invention is thus, according to one of its aspects, an assembly, the assembly comprising - a stack of solid oxide cells of the SOEC / SOFC type operating at high temperature, the stack of solid oxide cells of the SOEC / SOFC type comprising - a plurality of electrochemical cells respectively formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects respectively arranged between two adjacent electrochemical cells, a stack of solid oxide cells of the SOEC / SOFC type, and - a system for clamping the stack of solid oxide cells of the SOEC / SOFC type, the system comprising an upper clamping plate and a bottom clamping plate, the stack of solid oxide cells of the SOEC / SOFC type being clamped between the upper clamping plate and the bottom clamping plate, each clamping plate comprising at least two clamping orifices, the clamping system comprising - at least two clamping rods, the at least two clamping rods being intended to extend respectively through the clamping orifices of the upper clamping plate and through the corresponding clamping orifices of the bottom clamping plate in order to enable the upper clamping plate and the bottom clamping plate to be assembled together, and Clamping means in the respective clamping orifices of the upper clamping plate and the bottom clamping plate, intended to cooperate with said at least two clamping rods in order to enable the upper clamping plate and the bottom clamping plate to be assembled together and a system further comprising In an assembly comprising At least one of the upper clamping plate and the bottom clamping plate includes a housing, the housing being formed in the thickness of said at least one of the upper clamping plate and the bottom clamping plate, the housing including a first end and a second end on opposite sides of each other, at least one of the first end and the second end appearing on the lateral surface of said at least one of the upper clamping plate and the bottom clamping plate, the housing being positioned substantially parallel to each other inside said at least one of the upper clamping plate and the bottom clamping plate at a predetermined distance from its main upper and bottom surfaces The assembly includes at least one heating plate, the at least one heating plate being removable and replaceable and being inserted into said housing, and is an assembly characterized thereby

[0050] According to the present invention, it is possible to maintain the benefits associated with the integration of heating elements into thick clamping plates, which improves the thermal efficiency of SOEC / SOFC type stacks while minimizing heat loss and maintaining the same sizing of the elements of the self - contained clamping system described above. In addition, the principle of the present invention makes it possible to make one or more heating elements removable and replaceable (especially in the case of their failure).

[0051] The assembly according to the invention can further include one or more of the following features, either alone or in any technically possible combination.

[0052] The housing and the at least one heating plate can have a substantially parallelepiped shape, in particular a slab shape or a cubic shape.

[0053] Furthermore, the housing can be formed centrally, at an equal distance from the main upper and bottom faces, and at an equal distance from the clamping orifices between the clamping orifices, within the thickness of at least one of the upper clamping plate and the bottom clamping plate.

[0054] In addition, the thickness of the housing can be between 5 mm and 10 mm, in particular on the order of 8 mm. The width of the housing can be between 20 mm and 86 mm for a part of it, in particular on the order of 86 mm.

[0055] Furthermore, the at least one heating plate can include a heating element, and the maximum power of the heating element can be at least 1200 W.

[0056] The at least one heating plate can be manufactured from ceramic or metal alloy, in particular from stainless steel or nickel-based alloy, and is in particular treated with an aluminizing coating.

[0057] In addition, a gap can exist between the outer surface of the at least one heating plate and the inner surface of the housing, and the dimension of the gap can be between 0.2 mm and 0.5 mm.

[0058] Furthermore, at least one of the upper clamping plate and the bottom clamping plate can include at least one internal groove, the at least one internal groove being formed within the thickness of at least one of the upper clamping plate and the bottom clamping plate, extending substantially parallel to its upper and bottom surfaces, and at least one end of the at least one internal groove appearing on the lateral surface of at least one of the upper clamping plate and the bottom clamping plate. The assembly can then include at least one thermocouple device inserted into the at least one internal groove.

[0059] In particular, the at least one internal groove can include a first safety internal groove and a second adjustment internal groove. The at least one thermocouple device can include a first safety thermocouple device inserted into the first internal groove and a second adjustment thermocouple device inserted into the second internal groove.

[0060] Furthermore, the assembly can include an upper end plate and a bottom end plate, with a plurality of electrochemical cells and a plurality of intermediate interconnects clamped between the upper end plate and the bottom end plate.

[0061] In addition, at least one of the upper clamping plate and the bottom clamping plate can advantageously be manufactured by additive manufacturing techniques and, in particular, be made of a refractory austenitic steel (such as, in particular, of the AISI 310 type).

[0062] Furthermore, at least one of the upper clamping plate and the bottom clamping plate can have a thickness between 20 mm and 30 mm and, in particular, can have a thickness on the order of 25 mm.

[0063] In addition, according to another aspect of the present invention, there is provided a system, the system comprising: - an assembly as defined above; - a device having at least one gas inlet and / or outlet tube connected thereto, and a stack of solid oxide cells of the SOEC / SOFC type operating at high temperature being coupled to the device for gas ingress and egress. The system is characterized by comprising the above.

[0064] Furthermore, according to another aspect of the present invention, there is provided a method for manufacturing an assembly as defined above, the method being characterized by including the step of generating the housing in at least one of the upper clamping plate and the bottom clamping plate.

[0065] The step of generating the housing may include, for example, generation by electro-erosion, hubbing, and / or additive manufacturing.

[0066] The present invention can be best understood from reading the following detailed description of non-limiting examples of its implementations and examining the schematic partial views of the accompanying drawings.

Brief Description of the Drawings

[0067]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0068] In all these figures, the same reference signs can designate the same or similar elements.

[0069] In addition, the various parts shown in the figures are not necessarily shown at a uniform scale in order to make the figures easier to read.

[0070] FIGS. 1 to 4 have already been described previously in parts related to the prior art and the technical context of the present invention. Regarding FIGS. 1 and 2, for the supply of steam H 2 O, and also for hydrogen H 2 and oxygen O 2It is stated that the symbols and arrows regarding the distribution and recovery of air, and electric current are shown for the purpose of clarification and accuracy in order to illustrate the operation of the device shown.

[0071] Furthermore, it should be noted that all components (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramic. Additionally, the operating temperature of a high-temperature SOEC / SOFC type stack is typically between 600 °C and 1000 °C.

[0072] In addition, the terms "upper" and "lower" should here be understood in the normal direction of the orientation of an SOEC / SOFC type stack when in its use configuration.

[0073] Figures 5 to 9 relate to an exemplary embodiment of the assembly 80 according to the invention. In particular, Figure 5 shows an example of the assembly 80 according to the invention, similar to that previously described with reference to Figure 4. Therefore, elements common to Figures 4 and 5 will not be described again.

[0074] According to the invention, each upper clamping plate 45 and each lower clamping plate 46 comprise a housing 90. The features of such a housing 90 can best be seen with reference to Figures 6 to 8.

[0075] Each housing 90 is formed within the thickness e p of each upper clamping plate 45 and each lower clamping plate 46. It includes a first end 90a and a second end 90b which are on opposite sides of each other and both appear on the lateral face FL of the respective clamping plates 45, 46.

[0076] The housing 90 is formed inside the corresponding clamping plates 45, 46 and passes over the longitudinal axis while passing through the center of the plates. Thus, it is disposed at the center inside the clamping plates 45, 46. In particular, as seen in FIG. 6 relating to the upper clamping plate 45, the housing 90 is formed at an equal distance from the clamping orifices 54 between the clamping orifices 54. Similarly, as seen in FIG. 8 relating to the bottom clamping plate 46, the housing 90 is formed at an equal distance from the passage holes 97 for the entry and / or exit of gas. Thus, each housing 90 is intended to receive a heating plate 95, as seen in FIG. 5. Each heating plate 95 is supplied by a supply wire 98 that can be seen in FIG. 5. The positioning of the heating plates 95 provided with such an electrical feed in the form of a cable 98 can be done such that they are positioned outside the side that causes the least interference.

[0077] Each housing 90 and each heating plate 95 preferably have a substantially parallelepiped shape, and in particular, here they have a substantially slab shape, but they can also be cube-shaped or yet another shape.

[0078] Advantageously, the present invention thus allows the use of removable and replaceable heating plates. Thus, if the heating plate is damaged, it can be easily replaced.

[0079] The dimensions of the housing 90 and the heating plate 95 can vary according to various requirements, and in particular according to the nature of the heating plate used.

[0080] Generally, the thickness e of the housing 90 lis between 5 mm and 10 mm, here, for example, on the order of 8 mm, and the width l of the housing 90 is between 20 mm and 86 mm, here, for example, on the order of 86 mm.

[0081] Furthermore, the thickness e' of the heating plate 95 is between 5 mm and 10 mm, here, for example, on the order of 5 mm, and the width l' of the heating plate 95 (especially of its heating surface) is between 20 mm and 86 mm, here, for example, on the order of 84 mm, and the length L' of the heating plate 95 (especially of its heating surface) is between 210 mm and 220 mm, here, for example, on the order of 260 mm.

[0082] The housing 90 or the openings formed in the upper clamping plate 45 and the bottom clamping plate 46 can be produced in various ways. In particular, they can be obtained by the electroerosion method, by having (or, EDM, which is short for "electrical discharge machining" in English), and / or by additive manufacturing methods (especially including 3D printing).

[0083] First, electroerosion by having is a machining method that essentially involves removing material in a part using electric discharges. It is also called spark machining. This technique is characterized by its suitability for machining all conductive materials (such as metals, alloys, carbides, graphite, etc.) regardless of their hardness. This machining method essentially involves passing an electric current through a dielectric to generate vapor or void bubbles, which ionize and implode and are reabsorbed when imploding, causing the destruction of the material. This destruction (microimplosion) causes a spark. A high-intensity current ionizes the channel through the dielectric. Then, a destructive discharge occurs towards the part to be machined from the electrode, locally affecting the latter very much (by a few μm2 Damage it in the order of). Next, the dielectric cools the damaged particles, and the particles fall into the mechanical tray in the form of sludge (micro-particles of the material and the dielectric).

[0084] Second, additive manufacturing techniques use a digital file model and a machine that uses methods such as the extrusion or solidification of metal, polymer, and polymer thread powders to enable the step-by-step creation of an object. It is called "Layer by layer" printing. 3D printing corresponds to the deposition of materials by melting, selective filtering by an energy source (laser, heating element, electron beam, or ultraviolet light) that enables the assembly of the object, and finally, the solidification of the material during the cooling period (except in the case of stereolithography where a chemical phenomenon of polymerization of a photocurable resin occurs). The machine prints each layer in turn, one layer on top of the other, thereby constructing a real object inside the machine's build chamber. When the 3D printer finishes the last layer, a short drying cycle begins. Then, the real object can be removed and, if necessary, may undergo finishing treatments such as sanding or hardening for hardness. Thus, manufacturing no longer consists of removing material as traditional techniques used to do with rolling or machining. Instead, in contrast, it consists of adding layer by layer to obtain the required material for the envisioned final object.

[0085] Furthermore, in order to be able to operate within the expected temperature range for a stack of SOFC / COEC type solid oxide cells, the heating plate 95 includes a heating element, and the maximum power of the heating element is at least 1200 W. Thus, they can achieve a power of approximately 1200 W ± 10% at 230 V, which corresponds to the maximum temperature of the high-temperature zone of 1000 °C with good insulation and appropriate regulation, and thus makes it possible to cover the power dissipated by the insulated chamber. The heating plate 95 can be commercially obtained, especially through companies specialized in high temperatures.

[0086] The heating plate can preferably be manufactured from ceramic. Various dimensions and sizes can be manufactured. Such a heating plate can have a high-temperature zone with an operating range up to 1000 °C and a low-temperature zone in the contact zone at 600 °C, which can be protected by a sheath made of ceramic wool. However, large heating plates can also be manufactured without a low-temperature zone. The special properties and low mass of the ceramic material can enable a rapid heating rate, uniform distribution of temperature, and accuracy of control. The high emissivity and wide emission spectrum of thermal radiation can make the ceramic material obtained from silicon nitride an ideal radiant heating element. A power of 15 W / cm at 1000 °C 2 can be achieved.

[0087] The heating plate can also be manufactured from a metal alloy. For example, they can be manufactured from stainless steel, such as 316L stainless steel, or from nickel-based alloys, especially from Inconel®. For example, from Inconel® 600. In this case, they are preferably treated with an aluminizing coating on their surfaces so that they do not weld to any surface they may come into contact with.

[0088] In addition, the heating plate can be composed of a heating cable, which is composed, among other things, of a heating core that is provided, for example, with a mineral insulator of the magnesium oxide (MgO) type of 96 - 99% under a sheath of Inconel® 600, and also has an integrated low - temperature termination end, illustrated by reference numeral 95t in FIG. 5. The heating core can have a diameter between 1 mm and 2 mm at ±0.05 mm over a given length.

[0089] Furthermore, as can be seen in FIG. 9, it should be noted that a gap J exists between the outer surface of the heating plate 95 and the inner surface of the housing 90. This gap J can have a dimension, among other things, between 0.2 mm and 0.5 mm.

[0090] When the heating plate 95 is inserted into its housing 90, it can be coated with thermal grease, which will have the effect of filling the gap J and achieving good heat transfer.

[0091] Each heating plate 45, 46 is made, for example, here, of a refractory material of the 310s stainless steel type. Its coefficient of thermal expansion at 850 °C is, for example, 18.2 (unit: 10 -6 .K -1 ) and it gives a movement of 0.012 mm at the 86 mm width l of the housing 90. It should be noted that the expansion of silicon nitride (ceramic) is negligibly small at the 86 mm width.

[0092] The following Table 1 represents data of interest (among other things, the coefficient of thermal expansion) for ceramic materials that can be used to manufacture the heating plate 95.

[0093]

Table 1

[0094] Furthermore, in order to be able to control each heating plate 95, each clamping plate 45, 46 includes internal grooves 100, 101, which are manufactured in the form of perforations, for example, to insert two thermocouple devices for each of the plates 45, 46.

[0095] Specifically, as can be seen in FIG. 9, a first safety internal groove 100 and a second adjustment internal groove 101 are formed in the upper clamping plate 45, enabling the insertion of each of the first safety thermocouple device and the second thermocouple device.

[0096] The first safety thermocouple device of the heating plate 95 is installed as close as possible to the zone to be controlled (i.e., as close as possible to the heating element) in order to avoid its overheating and damage. The second adjustment thermocouple device of the heating plate 95 is positioned within the zone of interest that enables obtaining information regarding the heat transfer to the stack 20.

[0097] Although expansion must also be considered, it is important to note that since a clamping force is generated in the bore of the clamping plate, the heating plate (preferably made of ceramic) can be damaged, so it is necessary to ensure that the plate does not bend.

[0098] In order to be able to perform finite element method calculations, a housing 90 of 86 mm x 8 mm was selected at the center of the clamping plate. Then, this is the case of verifying that the bending of the clamping plate enables the insertion or removal of the heating plate 95 when the stack 20 is clamped under a clamping force of 500 N per tie rod. The calculations were performed at 800 °C using 310S steel as the material of the clamping plates 45, 46.

[0099] Subsequently, a bending on the order of 1 micron was obtained, which was observed to be particularly problem-free for enabling the attachment and removal of the heating plate 95.

[0100] Naturally, the present invention is not limited to the exemplary embodiments described above. Various modifications can be made thereto by those skilled in the art.

Explanation of Reference Numerals

[0101] 1 Basic electrolysis cell 2 Cathode 2.1 Cathode 2.2 Cathode 3 Electrolyte 3.2 Electrolyte 4 Anode 4.2 Anode 5 Interconnector 10 Furnace bell 11 Furnace floor 12 Loop tube 13 Device 20 SOEC / SOFC type solid oxide stack 41 Electrochemical cell 42 Intermediate interconnector 43 Upper end plate 44 Bottom end plate 45 Upper clamping plate 46 Bottom clamping plate 50 Cathode compartment 51 Anode compartment 54 Clamping orifice 55 Clamping rod 56 Clamping means 57 Clamping means 58 Clamping means 60 Clamping system 80 Assembly 90 Housing 90a First end 90b Second end 95 Heating plate 95t Low-temperature end part 97 Passage hole 98 Cable 100 First safety internal groove part 100a End part of the internal groove 100 101 Second adjustment internal groove part 101a End part of the internal groove 101 C1 Basic electrolytic cell C2 Basic electrolytic cell e l Thickness of the housing 90 e p Thickness of the upper clamping plate 45 and the bottom clamping plate 46 e' Thickness of the heating plate 95 FI Bottom surface FL Lateral surface FS Upper surface J Gap l Width of the housing 90 L' Length of the heating plate 95 l' Width of the heating plate 95 PC High-temperature part PF Low-temperature part

Claims

1. An assembly (80), wherein the assembly (80) comprises: - A stack (20) of solid oxide cells of the SOEC / SOFC type operating at high temperature, - A plurality of electrochemical cells (41) respectively formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects (42) respectively disposed between two adjacent electrochemical cells (41), the stack (20) of solid oxide cells of the SOEC / SOFC type; and - A clamping system (60) for clamping the stack (20) of solid oxide cells of the SOEC / SOFC type, the clamping system (60) including an upper clamping plate (45) and a bottom clamping plate (46), the stack (20) of solid oxide cells of the SOEC / SOFC type being clamped between the upper clamping plate (45) and the bottom clamping plate (46), each clamping plate (45, 46) including at least two clamping orifices (54), and the clamping system (60) comprising: - At least two clamping rods (55), the at least two clamping rods (55) being intended to extend respectively through the clamping orifices (54) of the upper clamping plate (45) and through the corresponding clamping orifices (54) of the bottom clamping plate (46) to enable the upper clamping plate (45) and the bottom clamping plate (46) to be assembled together; and - Clamping means (56, 57, 58) at the respective clamping orifices (54) of the upper clamping plate (45) and the bottom clamping plate (46) intended to cooperate with the at least two clamping rods (55) to enable the upper clamping plate (45) and the bottom clamping plate (46) to be assembled together, the clamping system (60); in the assembly (80). At least one of the upper clamping plate (45) and the bottom clamping plate (46) includes a housing (90), the housing (90) is formed within the thickness (ep) of at least one of the upper clamping plate (45) and the bottom clamping plate (46), the housing (90) includes a first end (90a) and a second end (90b) on opposite sides of each other, and at least one of the first end (90a) and the second end (90b) appears on the lateral surface (FL) of at least one of the upper clamping plate (45) and the bottom clamping plate (46), and the housing (90) is positioned parallel to each other inside at least one of the upper clamping plate (45) and the bottom clamping plate (46) at a predetermined distance from its main upper surface (FS) and bottom surface (FI). The assembly (80) includes at least one heating plate (95), the at least one heating plate (95) is removable and replaceable, and is characterized by being inserted into the housing (90), assembly (80).

2. The assembly according to claim 1, wherein the housing (90) and the at least one heating plate (95) have a parallelepiped shape.

3. The housing (90) is within the thickness (ep) of at least one of the upper clamping plate (45) and the bottom clamping plate (46). - At an equal distance from the main upper surface (FS) and the bottom surface (FI) so that the housing (90) is formed at the center of the thickness (ep), and - Between the clamping orifices (54), at an equal distance from the clamping orifices (54). The assembly according to claim 1 or 2, characterized by being formed.

4. The thickness (el) of the housing (90) is between 5 mm and 10 mm, and the width (l) of the housing (90) is between 20 mm and 86 mm. The assembly according to any one of claims 1 to 3.

5. The assembly according to any one of claims 1 to 4, wherein the at least one heating plate (95) includes a heating element, and a maximum power of the heating element is 1200 W.

6. The assembly according to any one of claims 1 to 5, wherein the at least one heating plate (95) is manufactured from a ceramic or a metal alloy and is treated with an aluminizing coating.

7. The assembly according to any one of claims 1 to 6, wherein a gap (J) exists between an outer surface of the at least one heating plate (95) and an inner surface of the housing (90), and a dimension of the gap (J) is between 0.2 mm and 0.5 mm.

8. The assembly according to any one of claims 1 to 7, wherein at least one of the upper clamping plate (45) and the bottom clamping plate (46) includes at least one internal groove (100, 101), the at least one internal groove (100, 101) is formed in the thickness (ep) of at least one of the upper clamping plate (45) and the bottom clamping plate (46), extends parallel to an upper surface (FS) and a bottom surface (FI) thereof, and at least one end (100a, 101a) of the at least one internal groove (100, 101) appears on a lateral surface (FL) of at least one of the upper clamping plate (45) and the bottom clamping plate (46), and the assembly (80) includes at least one thermocouple device inserted into the at least one internal groove (100, 101).

9. The assembly according to claim 8, wherein the at least one internal groove (100, 101) includes a first safety internal groove (100) and a second adjustment internal groove (101), and the at least one thermocouple device includes a first safety thermocouple device inserted into the first safety internal groove (100) and a second adjustment thermocouple device inserted into the second adjustment internal groove (101).

10. The assembly includes an upper end plate (43) and a bottom end plate (44), and the plurality of electrochemical cells (41) and the plurality of intermediate interconnects (42) are clamped between the upper end plate (43) and the bottom end plate (44). The assembly according to any one of claims 1 to 9, characterized in that.

11. The assembly according to any one of claims 1 to 10, characterized in that at least one of the upper clamping plate (45) and the bottom clamping plate (46) is manufactured by an additive manufacturing technique and is made of a refractory austenitic steel.

12. The assembly according to any one of claims 1 to 11, characterized in that at least one of the upper clamping plate (45) and the bottom clamping plate (46) has a thickness between 20 mm and 30 mm.

13. A method for manufacturing an assembly (80) according to any one of claims 1 to 12, the method comprising the step of generating the housing (90) in at least one of the upper clamping plate (45) and the bottom clamping plate (46). A method, characterized in that.

14. The method according to claim 13, characterized in that the step of generating the housing (90) includes generation by electroerosion, by hobbing, and / or by additive manufacturing.

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