Electrolysis or co-electrolysis module (SOEC) or fuel cell (SOFC) with pre-assembled subsets of stacked electrochemical cells and a thermal enclosure housing the subsets and with thermal management hatch(es).

Abstract

Electrolysis or co-electrolysis module (SOEC) or fuel cell (SOFC) with pre-assembled sub-modules of stacked electrochemical cells and a thermal enclosure housing the sub-modules, with thermal management hatch(es). The invention relates to a module (1) designed to operate at high temperature with a thermal enclosure in which sub-modules (SM1, SM2), consisting of stacked electrochemical cells, are housed. At least one heat dissipation hatch (110) for the heat released inside the enclosure by the operating sub-modules allows for thermal management at the module level. Figure for the abstract: Fig. 7B

Description

Title of the invention: Electrolysis or co-electrolysis module (SOEC) or fuel cell (SOFC) with pre-assembled subsets of stacked electrochemical cells and a thermal enclosure housing the subsets and with thermal management hatch(es). technical field

[0001] The present invention relates to the field of solid oxide fuel cells (SOFCs), that of high-temperature steam electrolysis (HTE, EVHT, or HTSE), also with solid oxides (SOECs, SOE or SOEL), and that of high-temperature co-electrolysis of steam and carbon dioxide (CO2). Generically, this technological field is often referred to as SOCs, which relates to both the electrochemical operating modes of high-temperature steam electrolysis or co-electrolysis (EHT) of the SOEC type, or that of a fuel cell of the SOFC type.

[0002] The present invention relates to electrochemical devices that can constitute both an EHT electrolysis reactor and, reversibly, a fuel cell, depending on the needs and uses. These devices are usually referred to by the English acronym rSOC for "reversible Solid Oxide Cell".

[0003] The present invention aims primarily to improve the thermal management of such devices with stacks of elementary electrochemical cells, on the scale of a module which integrates several of them.

[0004] Although described primarily with reference to the application of high-temperature steam electrolysis, the invention applies equally well to co-electrolysis of steam and another gas such as carbon dioxide CO2, to a SOFC fuel cell, or to a reversible system allowing operation in both modes.

[0005] The invention applies to a SOFC fuel cell using as fuel either hydrogen, or a hydrocarbon-based fuel, for example methane CH4 or more broadly natural gas, or another non-carbon fuel such as ammonia. Previous technique

[0006] The electrolysis of water is an electrochemical reaction that decomposes water into dioxygen and dihydrogen gas with the aid of an electric current according to the reaction: HaO + 172 02

[0007] To carry out the electrolysis of water, it is advantageous to carry it out at high temperature typically between 600 and 950°C, because part of the energy required for the reaction can be supplied by heat which is cheaper than electricity and the activation of the reaction is more efficient at high temperature and does not require a specific catalyst.

[0008] As schematically shown in [Fig. 1], a solid oxide electrolysis cell 10, or "SOEC" (Anglo-Saxon acronym "Solid Oxide Electrolysis Cell"), includes in particular:

[0009] - a first porous conducting electrode 12, or "cathode", intended to be supplied with steam for the production of dihydrogen,

[0010] - a second porous conducting electrode 14, or "anode", through which escapes the dioxygen (O2) produced by the electrolysis of water vapor injected at the cathode, and

[0011] - a solid oxide membrane (dense electrolyte) 16 sandwiched between the cathode 12 and anode 14, membrane 16 being anionic conductive for high temperatures, usually temperatures above 600°C.

[0012] By heating the cell 10 at least to this temperature and by injecting an electric current 1 between the cathode 12 and the anode 14, there is then a reduction of water vapor on the cathode 12, which generates dihydrogen (H2) at the cathode 12 and dioxygen at the anode 14.

[0013] To implement high-temperature electrolysis, it is known to use a SOEC (Solid Oxide Electrolysis Cell) type electrolyzer, consisting of a stack of elementary units, each comprising a solid oxide electrolysis cell made up of three anode / electrolyte / cathode layers stacked one on top of the other, and interconnecting plates made of metallic alloys, also called bipolar plates, or interconnectors. The interconnectors serve to ensure both the passage of electric current and the circulation of gases in the vicinity of each cell (injected water vapor, extracted hydrogen and oxygen in an EHT electrolyzer; injected air and fuel (particularly hydrogen) and extracted water in a SOFC) and to separate the anodic and cathodic compartments, which are the gas circulation compartments on the anode and cathode sides of the cells, respectively.To perform high-temperature steam electrolysis (HTE), water vapor (H2O) is injected into the cathode compartment. Under the effect of the current applied to the cell, the water molecules dissociate. Hydrogen vaporization occurs at the interface between the hydrogen electrode (cathode) and the electrolyte: this dissociation produces hydrogen gas (H2) and oxygen ions. The hydrogen is collected and discharged from the hydrogen compartment. The oxygen ions (O2) migrate through the electrolyte and recombine into oxygen at the interface between the electrolyte and the oxygen electrode (anode).

[0014] To ensure the operation of a SOFC fuel cell, air (oxygen) is injected into the cathode compartment and a fuel, in particular hydrogen, into the anode compartment. The oxygen from the air dissociates into oxygen ions (O2) which migrate through the electrolyte and combine with dihydrogen (H2) at the anode to form water vapor and release electrons that are captured by the external electrical circuit.

[0015] To increase the flow rates of hydrogen and oxygen produced in the case of EHT electrolysis or to increase the electrical power supplied in the case of a SOFC fuel cell, it is known to stack several elementary electrochemical cells one on top of the other, separating them by interconnectors. The assembly is positioned between two end connection plates that support the electrical power supplies and the gas supply / collection connections of an electrolyzer (electrolysis reactor) or an SOFC fuel cell.

[0016] Furthermore, to improve the quality of the electrical contacts established between the interconnectors and the electrodes, and thus the performance of the aforementioned electrochemical devices, electrical contact elements are individually intercalated and arranged on the electrodes. In an electrochemical device, a nickel grid is conventionally used for contact with the hydrogen electrode (cathode in an EHT reactor, anode in a SOFC cell), because it provides satisfactory results at low cost.

[0017] A stack 20 of electrolysis cells, intended to produce a significant quantity of hydrogen, is illustrated in Figure 2. In particular, the cells 10 are stacked one on top of the other, separated by interconnecting plates 18 connected to a steam supply manifold 22 for injecting this steam onto the cathodes of the cells 10 according to a steam flow rate Dh,O regulated by a flow control device, for example a controllable valve 24. The plates 18 are also connected to two gas collectors 24, 26 for collecting the gases from the electrolysis, hydrogen (plus the possibly unconsumed fraction of water vapor (H2O)) and oxygen respectively.

[0018] An example of stacking and interconnecting plate structure is described in patent application WO 2011 / 110676.

[0019] Such an electrolyzer can also operate in co-electrolysis, that is, with a gas mixture at the cathodic inlet composed of water vapor (H2O) and carbon dioxide (CO2). The mixture at the cathodic outlet then consists of hydrogen (H2) and carbon monoxide (CO), plus any unconsumed fractions of water vapor (H2O) and carbon dioxide (CO2).

[0020] For the effective implementation of electrolysis by the stack 20, the stack is brought to a temperature above 600°C, usually a temperature between 600°C and 950°C, the gas supply is started at a constant flow rate and an electrical power supply 28 is connected between two terminals 30, 32 of the stack 20 in order to circulate the current 1.

[0021] The same solid oxide electrochemical device can operate reversibly in high-temperature electrolysis mode (SOEC) and in fuel cell mode (SOFC).

[0022] In other words, a high-temperature solid oxide fuel cell and an EVHT electrolyzer can have identical structures, only their mode of operation being different. Referring to [Fig. 3], an electrochemical cell 10 constituting a SOFC fuel cell comprises the same elements, namely the anode 12, the cathode 14, the electrolyte 16, as an electrolysis cell.

[0023] A cell of the fuel cell is supplied, on its anode by dihydrogen or another fuel such as methane CH4, and on its cathode by pure dioxygen or dioxygen contained in the air supplied, and connected to a load C to deliver the electric current produced.

[0024] On the other hand, the two modes of production, either electrical in SOFC and chemical species (H2, O2) in SOEC, present very different thermal regimes in operation.

[0025] In SOFC (single-phase fuel cell) mode, since the oxidation of the fuel (hydrogen) is exothermic, heat is produced regardless of the operating point (current / voltage). This production is sustained by the flow of electric currents, generating the Joule effect. The intensity of the thermal power produced thus depends directly on the electricity production. For a given production level, a thermal equilibrium must be established to prevent a temperature rise in a single cell, and in the stacking of cells, which would be detrimental to their operation. To achieve this equilibrium, it is possible, within certain limits, to adjust the temperature of the reactants and the reactant flow rates, particularly of the oxidant. However, this proves insufficient if the system operates at the high utilization rates and currents required for economic efficiency.

[0026] In the case of operation of a fuel cell powered by methane (CH4) or ammonia (NH3), the steam reforming (CH4) or reforming (NH3) reactions (see publication [1]) are endothermic and catalyzed by the nickel present in the anode of the hydrogen compartment, which creates a thermal power sink. The net power of this sink is proportional to the amount of fuel reformed and independent of the current generated. This situation shifts the thermal equilibrium with respect to production from pure H2 as fuel, in a direction that is favorable to increasing, all other things being equal, the electrical power supplied.

[0027] Depending on the current intensity and fuel feed rate, the heat balance can be negative, meaning that the heat consumed by the reforming / steam reforming reactions is greater than the heat resulting from the oxidation of the H2 and CO fuels. This occurs at low currents and utilization rates. It can also be positive, meaning that the heat produced by the oxidation of H2 and CO is greater than that consumed by the reforming / steam reforming reactions. In the case of economically viable systems where the fuel utilization rate and current production must be maximized, the heat balance tends towards a net heat production and the need to extract thermal power, as is the case with pure H2 feed.

[0028] The electrolysis reaction of water vapor is the reverse reaction of hydrogen oxidation; it is therefore endothermic. In this case, the amount of vapor dissociated, as well as the ohmic losses, depend on the electrolysis current and thus on the supply voltage. Depending on the voltage at which an electrolysis cell is operated, three thermal regimes are observed.

[0029] At the thermoneutral voltage (TNT), deduced from the enthalpy of dissociation of the water vapor molecule, i.e. approximately 1.3V at the operating temperature of 800°C, the heat generated by the irreversibilities exactly compensates for the endothermicity of the electrolysis reaction.

[0030] If the cell operating point corresponds to a voltage higher than this value, then the operation is exothermic because the production term related to irreversibilities is greater than the thermal consumption by electrolysis, and conversely an operating point at a lower voltage leads to an endothermic regime.

[0031] The different thermal regimes involved for an operating mode in SOEC electrolysis or in SOFC fuel cell are explained in [Fig.4], in the form of cell voltage curves as a function of current density.

[0032] It is clear from these curves that it is necessary to remove the heat produced in SOFC fuel cell operating mode. By way of illustration, for a module comprising several electrochemical devices with stacked elementary cells, producing in SOFC mode an electrical power of around 50 kW with a hydrogen H2 supply and which has an electrical efficiency of 60%, the thermal power to be extracted amounts to 33.3 kW.

[0033] For low-temperature fuel cells, such as PEMFCs, cooling is achieved via a liquid water circuit. This solution is not feasible for a SOFC fuel cell at operating temperature.

[0034] The solutions classically considered for removing the heat released by SOFC fuel cells can be listed as follows:

[0035] - part of the exothermicity of the hydrogen oxidation reaction is compensated by the endothermicity of the steam reforming reaction when the fuel cell is powered by carbonaceous (CH4) or ammonia-based fuels. Taking the previous example of a fuel cell producing, this time from natural gas, an electrical power of around 50 kW with an efficiency of around 60% and an air boost factor of two, in which 90% of the steam reforming takes place within the fuel cell stacks, the thermal power to be extracted can be reduced to 5.5 kW. This solution is not feasible when the fuel is hydrogen;

[0036] - sending a flow of air to the oxygen electrode much higher than what is necessary for the electrochemical reaction, with the excess airflow allowing the heat produced to be removed. This solution works, but leads to increased air consumption, with both material consumption and energy required for its distribution. It also necessitates larger cross-section upstream / downstream piping, assuming equal pressure loss along the fluid circuit. Thus, the fuel cell becomes less compact and more expensive. Furthermore, with a constant stacking geometry, this induces a pressure increase in each cell stack, potentially detrimental to its lifespan, as the excess airflow for a complete fuel cell cannot exceed a certain value, and in this case, it does not allow the total thermal power produced to be removed.

[0037] - the choice of a low-current operating point, inducing a production limited heat and easier to extract or compensate for by the two previous solutions. In this case, the number of electrochemical cells and / or the size of a cell stack must be higher for a given power, which has a direct impact on the amount of investment required to develop a module and a complete multi-module system.

[0038] - an injection of air as an oxidizer, at an operating temperature lower than that intended for the battery, in order to allow this air to dissipate more heat.

[0039] Conversely, in electrolysis operating mode, as shown in the curves of [Fig.4], depending on the operating point chosen, heat must either be supplied or removed, even if in practice, at the scale of a module integrating several stacked electrochemical devices and of a system with several modules, in nominal operation, a thermal regime point around the thermoneutral point is preferred in order to simplify thermal management.

[0040] The Applicant has proposed in patent EP3494608B1 a solution for an electrochemical device that can operate reversibly as a SOFC fuel cell or as a SOEC electrolyzer. The proposed solution consists of implementing a bypass line or circuit to divert, if necessary, a portion of the hot gases from the so-called oxygen chambers (anodic chambers in SOEC mode, cathodic chambers in SOFC mode). This limits the thermal power exchanged at the heat exchanger arranged in the oxygen circuit and, consequently, the oxygen inlet temperature to the cell stack. Excessive heating of the device is thus prevented in fuel cell operating mode, while in electrolysis mode, the bypass line is not used. In this electrolysis mode, it is possible to preheat the air entering the device using heat collected from the outlet gases, which allows for an increase in efficiency.

[0041] Thermal management therefore appears extremely critical in that it leads to the design of different electrochemical devices and thermal management strategies at the level of a module with multiple electrochemical devices and a system with multiple modules, depending on their operating mode in SOEC electrolysis or SOFC fuel cell. This is particularly exacerbated when reversible operation is envisaged with the same module that will alternately operate in SOEC electrolysis mode and in SOFC fuel cell mode.

[0042] There is therefore a need to find flexible thermal management solutions for a module with several electrochemical devices with stacked elementary electrochemical cells and / or for a system with several modules, whether it / they operate in SOEC electrolysis mode or reversibly in SOFC stack mode.

[0043] The aim of the invention is to meet at least part of this need. Description of the invention

[0044] To this end, the invention first relates to an electrochemical module, comprising:

[0045] - at least one pre-assembled sub-module, designed to operate at high temperature, including:

[0046] • a stack of SOEC-type solid oxide-based electrochemical cells / SOFC;

[0047] • a plurality of interconnectors with electrical distribution functions and fluidics, each comprising a component of electronically conductive and gas-tight material for bringing or collecting electric current to the cells and for bringing, collecting and circulating gases over each electrode of each electrochemical cell; the interconnectors being arranged individually on either side of each of the electrochemical cells;

[0048] - a thermal insulation enclosure, inside which is / are housed the pre-assembled sub-module(s), comprising, through at least one of its walls:

[0049] • at least one group of penetrations, preferably watertight, through which pass electrical power supply lines and fluid lines for reactive gas supply and evacuation of produced gases, from at least one pre-assembled sub-module;

[0050] • at least one evacuation hatch, movable between a closed position in which it maintains the thermal insulation of the enclosure from the outside and at least one opening position in which the heat released by at least one sub-module beyond a predetermined value is evacuated at least by natural convection.

[0051] The hot air that is evacuated through the hatch solely by natural convection depends on the initial sizing, in particular, the volume of the enclosure, the position, number and dimensions of the evacuation hatch(es).

[0052] According to an advantageous embodiment, the module further comprises:

[0053] - a system for blowing air or an inert gas;

[0054] - at least one insufflation hatch connected to the mobile insufflation system through one of the walls of the thermal enclosure between a closed position in which it maintains the thermal insulation of the enclosure from the outside and an open position in which air or neutral gas is blown in from the operating system, so that when the exhaust flap is also in its open position the heat released by at least one sub-module beyond the predetermined value is evacuated by forced convection.

[0055] Thus, an active heat dissipation method is obtained, which is more efficient than the passive method of simple natural convection of hot air passing through the open exhaust vent to the outside. The airflow rate is determined by the heat output to be dissipated.

[0056] Operating an air blower will consume electrical power and lower the electrical efficiency of the module, when operating in stack mode of the electrochemical cell stacked sub-modules.

[0057] The operation of an air blower will be triggered in the event of overheating related to the operation of the sub-modules in battery mode or the operation of the sub-modules in electrolysis mode if it becomes too exothermic to the point of potentially damaging the lifespan of the electrochemical cell stacks and / or other components inside the enclosure. For example, these situations may occur in battery mode if high currents are applied to the stacks, and in electrolysis mode if voltages exceeding the thermo-neutral voltage are applied to them.

[0058] Advantageously, the opening of the evacuation hatch is controlled by the thermal operating regime of the sub-module(s).

[0059] Even more advantageously, the opening of the supply vent is linked to that of the exhaust vent. Thus, as soon as fresh air is supplied, the release of hot air is simultaneous.

[0060] According to an advantageous embodiment, the enclosure includes within it one or more of the baffles for circulating the air heated by the heat released to be evacuated through the evacuation hatch(es).

[0061] According to another advantageous variant, at least one sub-module is supported by the base of the enclosure.

[0062] According to an advantageous configuration, the enclosure includes at least one exhaust hatch in the wall forming the ceiling of the enclosure and at least one supply hatch in the base and / or a side wall of the enclosure so that, in at least one opening position of said hatches, the airflow generated by the released heat is carried away by the chimney effect.

[0063] According to an advantageous embodiment, the enclosure consists of a metal casing filled with at least one thermally insulating material.

[0064] According to another advantageous variant, each hatch consists of a metal casing filled with at least one thermally insulating material.

[0065] Preferably, the thermal insulation material being a refractory material, in the form of bricks or fibers or foams or mats.

[0066] Preferably, the walls of the enclosure having a thickness between 10 and 50 cm.

[0067] Thus, the invention essentially consists of a module intended to operate at high temperature with a thermal enclosure in which electrochemical cell stacked sub-modules are housed. At least one heat dissipation hatch for the heat released inside the enclosure by the operating sub-modules allows for thermal management at the module level.

[0068] The solution is particularly well-suited for reversible sub-module operation, meaning that it can switch from fuel cell mode to electrolysis or co-electrolysis mode, as it allows the module's thermal management to be adapted to either of the two sub-module operating modes. The solution can, of course, also be implemented with sub-modules that operate solely as fuel cells, or solely as electrolyzers or co-electrolyzers.

[0069] An enclosure of a module according to the invention can comprise any number of sub-modules with stacked electrochemical cells, typically from 1 to several hundred, more reasonably between 1 and 100.

[0070] In practical implementation, each hatch can be delimited by cutting / machining / drilling through a wall of the thermal insulation enclosure. Its cross-sectional area in the open position and the choice of its shape will be determined to take into account the components, particularly the electrochemical sub-modules present within it. The total cross-sectional area of ​​the air passage depends on the heat to be dissipated, the size of the enclosure, and the number of electrochemical sub-modules inside.

[0071] Each hatch can be in the form of a pivoting or sliding opening, in particular in an enclosure wall, or foldable on itself.

[0072] As a system for opening each hatch, a simple manual handle can be considered, but also a motorized, controlled system. A controlled system may be preferred for potentially partial opening of all the hatches or only some of them, controlled according to the operating point of the sub-modules and the heat to be removed from the enclosure.

[0073] Other advantages and features will become clearer upon reading the detailed description, given by way of illustration and not limitation, with reference to the following figures. Brief description of the drawings

[0074] [Fig.1] [Fig.1] is a schematic view of an elementary electrochemical cell of an EHT electrolyzer.

[0075] [Fig.2] [Fig.2] is a schematic view of a cell stacking according to the [Fig.l].

[0076] [Fig.3] [Fig.3] is a schematic view of an electrochemical cell of a SOFC fuel cell.

[0077] [Fig.4] [Fig.4] illustrates in the form of a curve the voltage of a cell solid oxide electrochemical reaction as a function of current density, when operating in EHT electrolyzer mode or in fuel cell mode.

[0078] [Fig. 5] [Fig. 5] is a schematic longitudinal cross-sectional view of an example of a stacked assembly of electrochemical cells with its interconnectors and two clamping plates on either side forming a sub-module functioning as an EHT electrolyzer and reversibly as a SOFC fuel cell.

[0079] [Fig.6] [Fig.6] illustrates the different levels of integration from a cell elemental electrochemical solid oxides with an interconnector up to a complete system that can operate reversibly in electrolysis mode EHT for hydrogen production or in fuel cell SOFC mode for electricity production.

[0080] [Fig. 7A], [Fig. 7B] Figures 7A and 7B schematically illustrate a module a thermal insulation enclosure according to an embodiment of the invention with vents for the natural convection evacuation of heat released by the sub-modules, in respectively closed and open positions.

[0081] [Fig.8A], [Fig.8B] Figures 8A and 8B schematically illustrate a module to a thermal insulation enclosure according to another embodiment of the invention comprising a system for blowing air or neutral gas to remove heat by forced convection, with the hatches in respectively closed and open positions.

[0082] [Fig.9] [Fig.9] illustrates a variant of utilizing the heat evacuated from the module according to figures 7A and 7B.

[0083] [Fig. 10] [Fig. 10] illustrates a variant of recovery of the heat evacuated from the module according to figures 8A and 8B. Detailed description

[0084] Figures 1 to 4 have been commented on in the preamble and will therefore not be detailed thereafter.

[0085] Throughout this application, the terms "lower", "upper", "above", "below", "inside", "outside", "internal" "external" are to be understood by reference to an electrochemical device according to the invention in its vertical operating configuration.

[0086] It is also specified that the electrolyzers or fuel cells described are of the solid oxide type (SOEC, English acronym for "Solid Oxide Electrolysis Cell" or SOFC, English acronym for "Solid Oxide Fuel Cell") operating at high temperature. Thus, all the constituents (anode / electrolyte / cathode) of an electrolysis cell or fuel cell are ceramics. The high operating temperature of an electrolyzer (electrolysis reactor) or a fuel cell is typically between 600°C and 950°C. Figure 5 shows an electrochemical device SM according to the invention that can operate reversibly as a high-temperature electrolyzer (HTE) or a SOFC fuel cell.

[0087] This SM device is a stack of 20 solid oxide-based electrochemical cells of the SOEC / SOFC type, which makes it possible to increase the power of production of hydrogen or reversibly of electricity compared to a single cell.

[0088] Within the stack 20, a plurality of interconnectors with electrical and fluidic distribution functions, not shown, are individually arranged on either side of each of the electrochemical cells, as illustrated in [Fig. 2]. Each interconnector consists of a component made of electronically conductive and gas-tight material for supplying or collecting electrical current to the cells and for supplying, collecting, and circulating gases over each electrode of each electrochemical cell.

[0089] Similarly, within the stack 20, a plurality of contact elements is arranged individually on each electrode of electrochemical cells and a plurality of sealing gaskets around each gas inlet / outlet and around each cell.

[0090] In other words, the SM device comprises a stack of cells with individual intercalation of interconnectors, contact elements and sealing gaskets as done according to the state of the art for a complete electrochemical device.

[0091] Furthermore, in order to limit the electrical contact resistance between an interconnector and the individual electrochemical cells that the interconnector connects, and to seal the electrochemical device, the SM device may include a clamping system with two clamping plates 200, 201 arranged on either side of the stack of electrochemical cells that it compresses. An example of such a clamping system is described, for instance, in application FR3045215A1, which ensures a substantially constant clamping force over a wide operating temperature range.

[0092] Thus assembled with the clamping system, the SM device forms a pre-assembled electrochemical sub-module which can operate reversibly in fuel cell mode or in high-temperature electrolysis mode and which can be handled, moved, transported.

[0093] Figure 6 illustrates the different levels of integration from a solid oxide electrochemical cell to a complete hydrogen or electricity production system as currently envisaged.

[0094] In this integration, an electrochemical module M comprises several sub-modules such as that described with reference to [Fig.5], and a complete system, which can constitute a production site in its own right, can comprise several modules.

[0095] According to the invention, for an electrochemical module M, a thermal insulation enclosure 100 is provided, inside which the pre-assembled sub-module(s) SMI, SM2 are housed.

[0096] The enclosure 100 can consist of a metal casing filled with at least one thermal insulating material, preferably a refractory, in the form of bricks or fibers or foams or mats.

[0097] Advantageously, the pre-assembled sub-modules SMI, SM2 are supported by the wall 102 forming the base of the enclosure.

[0098] As illustrated, for each pre-assembled sub-module SMI, SM2, power supply lines 210 (dashed lines) and fluid lines (solid lines) for reactive gas supply and product gas exhaust pass through the base 102 of the enclosure by means of penetrations, not shown. It should be noted that the representation of the lines is obviously schematic, the power lines being cables, and the fluid lines being pipes.

[0099] At least one evacuation hatch 110 is mounted in one of the walls 101, 102 of the enclosure, movable between a closed position in which it maintains the thermal insulation of the enclosure against the outside ([Fig.7A]) and at least one open position in which the heat released by the sub-modules SMI, SM2 beyond a predetermined value is evacuated by natural convection ([Fig.7B]).

[0100] In the illustrated example, an exhaust hatch 110 is mounted in the wall 101 forming the ceiling of the enclosure and several supply hatches 111 are mounted in the base 102 so that, in at least one opening position of said hatches, the airflow generated by the released heat is carried away by the chimney effect.

[0101] As symbolized by the arrows in [Fig.7B], the fresh air passing through the open hatches 111 is heated in the enclosure with the heat released by the sub-modules SMI, SM2 to evacuate it through the open hatch 110.

[0102] It is advantageous to provide for the opening of the hatches 111 to be controlled by that of the evacuation hatch 110 itself controlled by the predetermined value beyond which the heat must be evacuated.

[0103] One or more evacuation hatches can also be mounted in the side wall 103 and / or in the top wall 101 of the enclosure.

[0104] To improve the evacuation of heated air, one or more of the circulation baffles can be provided in enclosure 100.

[0105] The opening of each hatch 110, 111 is preferably controlled by the thermal operating regime of the sub-modules SMI, SM2.

[0106] To further improve the evacuation of heat released by the SMI, SM2 sub-modules, it is possible to consider blowing air into the enclosure 100 for evacuation by forced convection.

[0107] Figures 8A and 8B show an air or neutral gas blowing system 300 which is connected to the hatches 111, via pipes 310.

[0108] Thus, when the hatch 110 and the hatches 111 move from a closed position ([Fig.8A]) to an open position ([Fig.8B]), air or neutral gas is blown in from the operating system 300, and the heat released by the sub-modules SMI, SM2 beyond the predetermined value is removed by forced convection.

[0109] Here too, it is advantageous to plan to control the opening of the hatches 111 to that of the evacuation hatch 110 itself controlled to the predetermined value beyond which the heat must be evacuated.

[0110] Similarly, to improve the evacuation of heated air, one or more of the circulation baffles can be provided in enclosure 100.

[0111] An advantageous variant may consist of utilizing the heat from the air or neutral gas evacuated through the evacuation hatch 110, instead of evacuating it into the atmosphere.

[0112] A collection circuit can thus be provided, including at least one collection pipe 112 at the outlet of the vent 110, which, in the open position of the vent, will collect the hot air or neutral gas. This collection circuit incorporates a heat exchanger 300, preferably of the air-to-water type. This may be a finned-tube heat exchanger. Care must be taken, of course, to size the heat exchanger 300 so that the pressure losses it induces in the pipe 112 do not impede the circulation of the air or neutral gas flow.

[0113] Thus, the heat from the exhaust will be exchanged in the heat exchanger in order to make use of it, for example in a heating network. This can be an air-to-water type heat exchanger allowing heat to be exchanged between the outgoing air, or neutral gas, and water.

[0114] This recovery and utilization of hot air can be carried out in the case of the natural convection mode ([Fig.9]) or for hot air or neutral gas in the case of the forced convection mode ([Fig. 10]).

[0115] By way of example, for an enclosure height of approximately 3 m and an operating temperature of 700°C for the SMI and SM2 sub-modules within it, the estimated thermal power to be dissipated is approximately 2.3 kW. Thermal calculations indicate that the circular cross-sectional area for the passage of a fresh air flow, corresponding to the opening provided by one or more supply vents 111, should be approximately 4.6 x 10⁴ m², or a diameter of approximately 2.4 cm². The exhaust vent 110 may have a larger diameter.

[0116] The invention is not limited to the examples just described; in particular, features of the illustrated examples can be combined in unillustrated variants.

[0117] Other variants and improvements may be envisaged without departing from the scope of the invention.

[0118] If, in the illustrated examples, the module enclosure contains several cell-stacked sub-modules next to each other, stackings can be considered of several sub-modules stacked on top of each other, in addition to those placed next to each other, housed inside the enclosure in the form of multiple columns of sub-modules.

[0119] If in the illustrated examples only two sub-modules SMI, SM2 are shown inside a thermal insulation enclosure, the latter can contain several dozen or even hundreds. List of cited references

[0120] [1]: “Ammonia -Fed Fuel Cells _ a Comprehensive Review I Elsevier Enhanced Reader. Accessed March 28, 2021. https: / / doi.org / 10.1016 / j.rser.2016.01.120.

Claims

Demands

1. Electrochemical module (1), comprising: - at least one pre-assembled sub-module (SMI, SM2), intended to operate at high temperature, comprising: • a stack (20) of SOEC / SOFC type solid oxide-based electrochemical cells; • a plurality of interconnectors for electrical and fluid distribution functions, each comprising a component made of electronically conductive and gas-tight material for supplying or collecting electrical current to the cells and for supplying, collecting and circulating gases over each electrode of each electrochemical cell; the interconnectors being arranged individually on either side of each of the electrochemical cells;- a thermal insulation enclosure (100), inside which the pre-assembled sub-module(s) is / are housed, and comprising, through at least one of its walls: • at least one group of penetrations, preferably sealed, through which pass electrical supply lines (210) and fluidic lines for supplying reactive gases and for evacuating the produced gases, from at least one pre-assembled sub-module; • at least one exhaust hatch (110), movablely mounted between a closed position in which it maintains the thermal insulation of the enclosure against the outside and at least one open position in which the heat released by the at least one sub-module beyond a predetermined value is evacuated at least by natural convection.

2. Electrochemical module according to claim 1, the opening of the evacuation hatch being controlled by the thermal operating regime of the sub-module(s).

3. Electrochemical module according to claim 1 or 2, further comprising: - an air or neutral gas supply system (300); - at least one supply flap connected to the supply system, mounted movably through one of the walls of the thermal enclosure between a closed position in which it maintains the thermal insulation of the enclosure against the outside and an open position in which air or neutral gas is supplied from the operating system, so that when the exhaust flap is also in its open position the heat released by at least one sub-module beyond the predetermined value is removed by forced convection.

4. Electrochemical module according to claim 3, the opening of the supply hatch being controlled by that of the exhaust hatch.

5. Electrochemical module according to any one of the preceding claims, at least one sub-module being supported by the base of the enclosure.

6. Electrochemical module according to any one of the preceding claims, the enclosure comprising at least one exhaust hatch in the wall forming the ceiling of the enclosure and at least one supply hatch (111) in the base and / or a side wall of the enclosure such that, in at least one opening position of said hatches, the airflow generated by the released heat is carried away by the chimney effect.

7. Electrochemical module according to any one of the preceding claims, the enclosure comprising within it one or more of the baffles for circulating the air heated by the heat released to be evacuated through the evacuation hatch(es).

8. Electrochemical module according to any one of the preceding claims, the enclosure being made of a metal casing filled with at least one thermally insulating material.

9. Electrochemical module according to any one of the preceding claims, each hatch consisting of a metallic envelope filled with at least thermal insulating material.

10. Electrochemical module according to claim 8 or 9, the thermal insulating material being a refractory, in the form of bricks or fibers or foams or mats.

11. 18 Electrochemical module according to any one of the preceding claims, the sub-module comprising two clamping plates (200, 201) between which the stack is arranged.

12. Electrochemical module according to any one of the preceding claims, the walls of the enclosure having a thickness between 10 and 50 cm.

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