Solid oxide electrolyte electrochemical reactor comprising a heating device

Abstract

The invention relates to a solid oxide electrochemical reactor comprising: – at least one stack (2) of solid oxide electrochemical cells (3) arranged in a thermal chamber (4), each of these electrochemical cells (3) comprising a solid electrolyte layer arranged between two electrode layers; and – a device for heating the stack (2) to an operating temperature. The heating device comprises: – at least one heating plate (9) arranged in the stack (2), a susceptor insert being arranged at least partially in the heating plate (9); and – at least one induction coil (10) arranged outside the stack (2), facing the heating plate (9).

Description

[0001] SOLID OXIDE ELECTROLYTE ELECTROCHEMICAL REACTOR COMPRISING A HEATING DEVICE

[0002] TECHNICAL FIELD

[0003] The invention relates to the technical field of solid oxide electrochemical reactors, and more specifically solid oxide electrolyzers (SOEC, "Solid Oxide Electrolyzer Cell") and solid oxide fuel cells (SOFC, "Solid Oxide Fuel Cell"), operating at high temperature.

[0004] These electrolysers and fuel cells are electrochemical reactors of the same nature but with reverse operation, necessarily operating at high temperature, currently of the order of 600°C to 1000°C. In the case of an electrolyser, they make it possible to obtain dihydrogen and dioxygen from water (for the electrolysis of water), and in the case of a fuel cell, to provide electrical energy from dihydrogen, or another fuel, and dioxygen.

[0005] These electrochemical reactors consist of one or more stacks of electrochemical cells held tightly together to ensure electrical contacts and sealing. Each electrochemical cell has a layer of solid electrolyte sandwiched between two layers of electrodes. The solid electrolyte layer allows the transport of ions between the anodic and cathodic layers, the latter being the site of chemical reactions.

[0006] When a stack brings together several electrochemical cells, interconnection plates are generally interposed between the cells to ensure sealing between cells, as well as to manage the supply and collection of gases or liquids participating in the reaction.

[0007] Solid oxide electrochemical reactors have many specific features, particularly those related to high-temperature operation, corrosion, mechanical strength, the ability to withstand significant temperature variations, and energy consumption. Water, as a feedstock in the case of an electrolyzer and as a product in the case of a fuel cell, is treated in the form of steam at the operating temperature of the electrochemical reactor.

[0008] PRIOR ART

[0009] The high temperatures required for the operation of these solid oxide electrochemical reactors are generally achieved by placing the stack of cells in a furnace with a heating capacity of potentially significant power. Given the temperatures involved, such a furnace requires a bulky enclosure and thermal means with significant electrical consumption.

[0010] Document WO2017102657 describes an example of an electrochemical reactor comprising a stack of solid oxide cells arranged in a furnace. Constraints linked to strong temperature variations require the use of more complex means of clamping the stack because they are adapted to maintain constant clamping.

[0011] WO202084258 describes an electrochemical reactor intended to overcome some of the drawbacks of the previously described reactors, by providing heating means directly integrated into clamping plates. However, these means impose additional constraints on the construction of the stacks, and such reactors remain difficult to implement.

[0012] Documents WO2012095331, DE102019214617, and DE102019208896 describe solid oxide electrochemical reactors comprising induction heating means.

[0013] STATEMENT OF THE INVENTION

[0014] The aim of the invention is to improve the solid oxide electrochemical reactors of the prior art.

[0015] To this end, the invention relates to a solid oxide electrochemical reactor, comprising:

[0016] - at least one stack of solid oxide electrochemical cells arranged in a thermal enclosure, each of these electrochemical cells comprising a layer of solid electrolyte arranged between two layers of electrodes;

[0017] - a device for heating said stack to an operating temperature.

[0018] The heating device includes:

[0019] - at least one heating plate arranged in the stack, a susceptor insert being arranged at least partially in the heating plate;

[0020] - at least one induction coil arranged outside the stack, opposite the heating plate.

[0021] According to another object, the invention relates to a method for manufacturing an electrochemical reactor, comprising: a step of producing by additive manufacturing the heating plate with a cavity and a filling orifice; a step of pouring a molten susceptor material through the filling orifice; and a step of closing the filling orifice with a plug.

[0022] According to another object, the invention relates to a method for manufacturing an electrochemical reactor, comprising: a step of producing by additive manufacturing a portion of the structural envelope with a cavity corresponding to the housing of the susceptor insert; stopping the additive manufacturing and placing the susceptor insert in the cavity; and a step of resuming the additive manufacturing by forming a final thickness of the structural envelope, closing the cavity.

[0023] The invention enables direct heating of electrochemical reactor cells that is fast, efficient, precise, and reproducible. The heating plates are heated directly by a magnetic field, with little loss due to heating other elements, resulting in energy savings and rapid heating capacity. Heating is localized, constant, and precise, with more responsive temperature control.

[0024] The invention allows a heat supply while being minimally intrusive on the structure of the electrochemical reactor. Indeed, the proper functioning of the stacks constituting the electrochemical reactor requires: electrical insulation between two successive cells to avoid short-circuiting a cell; sealing between the inlet and outlet compartments; and good distribution of both the inlet gases and the produced gases. The invention thus makes it possible to maintain the integrity of the stacks, while providing them with a direct heat supply. Furthermore, the invention provides a solution at a lower production cost than the solutions of the prior art, by improving the energy efficiency of the electrochemical reactor in a context where the high operating temperature imposes additional energy consumption that must be minimized to increase the energy efficiency of the electrochemical reactor.

[0025] The invention also makes it possible to improve the insulation capacity of the thermal enclosure, by allowing this thermal enclosure to be sized as close as possible to the cell stacks, to return the received energy by radiation in order to also contribute to optimizing the thermal efficiency of the system.

[0026] The invention is compatible with the implementation of an air sweeping device, which is commonly provided in this field, making it possible in particular to detect a possible leak of hydrogen. This sweeping of air, or of another gas, is reduced here thanks to the possibility of adjusting the thermal enclosure as close as possible to the heated elements, and therefore reducing the swept volume, which also contributes to energy efficiency.

[0027] Among the different modes of heat transfer in the electrochemical reactor zone, the predominant mode at these operating temperature levels (from 600 to 1000°C, and commonly around 650°C to 800°C) are radiative exchanges by radiation, and the invention makes it possible to limit losses by radiation, because the exchange surface is reduced.

[0028] The invention thus makes it possible to recover the thermal conduction of the heat produced in the heating plates which will provide the energy necessary to raise the gases to the correct temperature.

[0029] Furthermore, the invention allows for a compact design by nesting the induction coil(s) and the thermal enclosure. The power supply to the heating means is also simplified, with no wiring required inside the thermal enclosure.

[0030] The electrochemical reactor according to the invention may include the following additional characteristics, alone or in combination:

[0031] - the susceptor insert is arranged in the thickness of the heating plate; - the heating plate comprises a structural envelope enclosing the susceptor insert in a hermetic manner;

[0032] - the structural envelope comprises a cavity for the susceptor insert, this cavity opening outside the structural envelope via a filling orifice, the filling orifice being closed by a plug of the same material as the structural envelope;

[0033] - the structural envelope is made of non-magnetic material;

[0034] - the structural envelope is made of stainless steel;

[0035] - the susceptor insert has a curie temperature lower than said operating temperature;

[0036] - the susceptor insert is made of ferromagnetic material;

[0037] - the susceptor insert is made of steel;

[0038] - the susceptor insert is made of cobalt;

[0039] - the susceptor insert is made of cobalt / nickel alloy;

[0040] - the susceptor insert is made of graphite;

[0041] - the heating plate has a stack clamping device;

[0042] - the electrochemical reactor comprises two heating plates, at two ends of the stack, and the clamping device is adapted to clamp the stack between the two heating plates;

[0043] - the induction coil is a flat coil arranged opposite the heating plate;

[0044] - the induction coil extends in a plane substantially parallel to the heating plate;

[0045] - the induction coil is arranged in the thickness of the thermal enclosure;

[0046] - the thermal enclosure comprises a wall made of thermally insulating material, with a housing for the induction coil; - the distance between the induction coil and the heating plate is approximately between 30 and 80 mm;

[0047] - the induction coil is formed from a tubular conductor, and the heating device comprises a device for cooling the induction coil by circulating a heat transfer fluid in the tubular conductor.

[0048] PRESENTATION OF FIGURES

[0049] Other characteristics and advantages of the invention will emerge from the non-limiting description which follows, with reference to the appended drawings in which:

[0050] - figure 1 illustrates a simplified example of an electrochemical reactor according to the invention, seen in perspective with its thermal enclosure in section;

[0051] - figure 2 schematically illustrates a stack of cells of the electrochemical reactor;

[0052] - Figure 3 is a front view of Figure 1;

[0053] - figure 4 illustrates the electrochemical reactor of figure 1 without its thermal enclosure;

[0054] - Figure 5 is a sectional view of Figure 4;

[0055] - Figure 6 illustrates a heating plate of the electrochemical reactor;

[0056] - Figure 7 is a sectional view of Figure 6;

[0057] - figure 8, figure 9, and figure 10 illustrate steps of manufacturing processes according to the invention.

[0058] Elements similar and common to the various embodiments bear the same reference numbers in the figures.

[0059] DETAILED DESCRIPTION

[0060] Figures 1 and 3 illustrate an example of a solid oxide electrochemical reactor 1 according to the invention, operating at high temperature.

[0061] This electrochemical reactor can be a solid oxide electrolyser or a solid oxide fuel cell, with an operating temperature of around 600 to 1000°C. This electrochemical reactor can also be reversible, being able to operate alternately in both modes (solid oxide electrolyser, or solid oxide fuel cell) but always at high temperature.

[0062] The electrochemical reactor 1 comprises a thermal enclosure 4 made of a suitable material which is refractory and thermally insulating. The thermal enclosure 4 surrounds the electrochemical reactor 1 to maintain it at the operating temperature. In Figures 1 and 3, the thermal enclosure 4 is seen in section.

[0063] The electrochemical reactor 1 further comprises a stack 2 of electrochemical cells 3 arranged in the thermal enclosure 4. The electrochemical reactor 1 may comprise as many stacks 2 as necessary, arranged side by side, in line with one another, or in any other arrangement. In the present example simplified for educational purposes, the electrochemical reactor 1 comprises a single stack 2. The thickness of this stack 2 is here, also for reasons of simplification, reduced and can of course be greater in practice.

[0064] The stack 2 is an alternation of electrochemical cells 3, and is illustrated functionally in the schematic exploded view of Figure 2. Each electrochemical cell 3 is an electrolyte-electrode assembly made by a multilayer assembly, generally made of ceramic, comprising a central layer of solid electrolyte 5 which conducts ions. The solid electrolyte layer 5 is formed of a solid, dense and sealed electrolyte, and is inserted between two layers of electrodes 6, 7 which constitute porous electrodes. Additional layers may also be provided to improve the functionality of these layers.

[0065] A stack 2 thus comprises at least one electrochemical cell 3, which is formed around a layer of solid electrolyte 5, arranged between two layers of electrodes 6, 7.

[0066] The pair of electrode layers 6, 7 comprises an anodic layer and a cathodic layer, depending on the nature of the electrochemical reactor 1: - when the electrochemical reactor 1 is a solid oxide fuel cell, one of these electrode layers 6, 7 will be the anode and will be the site of oxidation of the fuel, while the other electrode layer 6, 7 will be the cathode and will be the site of reduction of the oxidant;

[0067] - when the electrochemical reactor 1 is a solid oxide electrolyser, for the electrolysis of water, one of these electrode layers 6, 7 will be the anode and will be the seat of oxidation of the water vapour, while the other electrode layer 6, 7 will be the cathode and will be the seat of reduction producing dihydrogen.

[0068] The different stacked electrochemical cells 3 are separated by interconnection plates 8. The stack 2 is thus an alternating stack of these electrochemical cells 3 and the interconnection plates 8. The interconnection plates 8 are electronic conductors which ensure contact between the cathode of a cell 3 (in contact with one of the faces of an interconnection plate) and the anode of the following cell 3 (in contact with the other face of this interconnection plate). The schematic view of Figure 2 is a partial illustration of a stack 2 showing a central cell 3, an electrode layer 6 of the lower cell 3, and with two interconnection plates 8.

[0069] The interconnection plates 8 are known and are generally made of metal plates for supplying the cell 3 with electric current or for recovering the electric current produced by the cell 3. The interconnection plates 8 also serve to distribute the elements participating in the electrochemical reaction and to recover the products of the electrochemical reaction, thanks to channels 18 (grooves in the illustrated example). The arrows visible in Figure 2 illustrate the crossed path of these elements in the channels 18.

[0070] The interconnecting plates 8 also serve to separate the anode and cathode compartments of two adjacent electrochemical cells 3. For example, in the case of electrolysis: the cathode compartment contains water vapor and dihydrogen, product of the electrochemical reaction; and the anode compartment contains a draining gas (if provided) and dioxygen, another product of the electrochemical reaction both in the case of the electrolysis of water or carbon dioxide. In fuel cell mode, the anode compartment contains the fuel (such as dihydrogen), and the cathode compartment contains the oxidizer (such as oxygen from the air). In the simplified views of Figures 1 and 3 to 5, the stack 2 may consist of one or more cells 3. In the present example, the stack 2 consists of 12 or 24 cells.

[0071] The electrochemical reactor further comprises a heating device for bringing the electrochemical cells 3 present in the stack 2 to their operating temperature.

[0072] Figure 3 is a side view of the electrochemical reactor 1, with the thermal enclosure 4 in section, and shows the elements of the heating device. The heating device comprises at least one induction coil 10 arranged outside the stack 2 and at least one heating plate 9 arranged in the stack 2.

[0073] In this example, the electrochemical reactor 1 comprises two heating plates 9, each arranged at one end of the stack 2, as well as two induction coils 10 each arranged opposite a heating plate 9.

[0074] Alternatively, the heating device may comprise a different number of induction coils 10 and heating plates 9, and the latter may be distributed within the stack 2.

[0075] In the present example, in a particularly advantageous manner, the heating plates 9, arranged at the two ends of the stack 2, are further provided with a clamping device 11. In this example, the clamping device comprises bolts adapted to clamp the heating plates 9 towards each other. The heating plates 9 thus replace any other clamping means, ensuring a compressive force on the stack 2 to guarantee its proper functioning. Indeed, the proper functioning of the stack 2 requires in particular:

[0076] - electrical insulation between two successive interconnection plates 8, otherwise the cell 3 located between these two interconnection plates 8 will be short-circuited, as well as good electrical contact and a sufficient contact surface between the cells 3 and the interconnection plates 8. The lowest possible ohmic resistance is sought between cells 3 and interconnection plates 8;

[0077] - a seal between the two compartments (oxidizer and fuel) under penalty of recombination of the gases produced leading to a drop in efficiency and especially the appearance of hot spots damaging the stack 2;

[0078] - good distribution of gases both at the fuel inlet and in the recovery of products, otherwise there will be a loss of efficiency, inhomogeneity of pressure and temperature within the different cells 3, or even prohibitive degradation of the cells 3.

[0079] The electrochemical reactor 1 thus does not require any other means of compressing the cells than that provided by the heating plates 9. It can be devoid of any other clamping means.

[0080] The induction coils 10 are preferably arranged inside the thermal enclosure 4, in the thickness of the wall. This heating device operating by induction, this integration of the induction coils 10 has very little impact on the heating performance, and makes it possible to approach the thermal enclosure 4 as close as possible to the stack 2 which must be brought to the high operating temperature. Thus, the thermal enclosure 4 is adjusted until it comes almost into contact, or even into contact, with elements of the stack 2 so as to increase the insulation performance and thus increase the energy performance of the electrochemical reactor 1. Preferably, a reduced clearance is provided for the passage of a sweeping gas, for safety reasons.

[0081] In the present example, the distance between each induction coil 10 and the corresponding heating plate 9 is of the order of 30 mm to 80 mm, a value which can be modulated according to the characteristics chosen for the electrical power supply of the induction coil 10.

[0082] The thermal enclosure 4 is made of any insulating and refractory material suitable for the application. In this example, the thermal enclosure 4 is made of alkaline earth silicate (AES) wools providing thermal insulation suitable for the operating temperature.

[0083] Figure 4 is a perspective view similar to Figure 1 but illustrating the electrochemical reactor 1 without its thermal enclosure 4, so as to account for the mutual positioning of the induction coils 10 and the stack 2. The induction coils 10 are here constituted by a winding of a tubular conductor 12. The tubular nature of the conductor 12 makes it possible on the one hand to promote a film circulation of the current which is adapted here, and on the other hand to provide an internal conduit to allow liquid cooling of the induction coil 10, with a heat transfer fluid circulating in the tubular conductor 12.The induction coil 10 is therefore formed from a tubular conductor 12 and the heating device of the electrochemical reactor comprises a device for cooling the induction coil 10 by circulation of a heat transfer fluid in the tubular conductor 12, thanks to a suitable cooling circuit (equipped with conduits, pumps, etc., not shown).

[0084] In this example, the tubular conductor 12 forms a flat spiral with a diameter of the order of 120 mm. The tubular conductor 12 may have a diameter of the order of 10 to 12 mm, and form three concentric spiral diameters, for example 120 mm, 90 mm, and 60 mm.

[0085] The induction coil 10 is arranged in the thickness of the thermal enclosure 4, in a housing 19 which is made in the wall of insulating material of the thermal enclosure 19. The induction coil 10 is thus protected from the direct heat produced within the heating plates 9 so that this coil can be made of a material whose melting point is close to, or even lower than, the operating temperature. The induction coil can thus be made in particular of copper, despite the high operating temperatures of the stack 2, which is particularly advantageous.

[0086] Alternatively, or in addition, a ceramic plate may be interposed between the induction coil 10 and the heating plate 9, this ceramic plate being insensitive to magnetic fields and having a thickness of the order of 10 to 12 mm, and a diameter corresponding to the external diameter of the induction coil 10.

[0087] The housing 19 for the induction coil 10 comprises connection conduits (not shown) leading to the outside of the thermal enclosure 4, so that no connection relating to the heating device is to be provided on the stack 2. The induction coils 10 are adapted to induction heating of the heating plates 9, whether by eddy currents or by hysteresis. The induction coils 10 are used here to transfer electrical energy to the heating plates 9 via an alternating electromagnetic field. In a manner known in the field of induction heating, the alternating current flowing in the induction coils 10 creates an electromagnetic field inducing in turn in the heating plates 9 a symmetrical current mirroring that which passes in the coils 10.

[0088] The induction coils 10 may have any alternative shape, suitable for their insertion into the electrochemical reactor 1. The induction coils 10 may for example consist of a helical winding (solenoid type) formed of a certain number of turns of a tubular copper conductor wound on a mandrel which would be in thermal conductivity with the heating plate(s) 9.

[0089] Preferably, the induction coil 10 extends, in this example, in a plane substantially parallel to the heating plate 9. The shape of the induction coil 10 of the illustrated example, in a plane spiral, is adapted to cooperation with plane heating plates 9, by placing the two corresponding planes opposite each other and substantially perpendicular. The arrangement of the heating plates 9 at the two ends of a stack 2 makes it possible, in addition to the clamping functions, to obtain an optimal distance between each induction coil 10 and the corresponding heating plate 9.

[0090] In the present example, the induction coils 10 are powered, in a conventional manner in the field of induction heating, by a power supply which comprises an inverter with an oscillating circuit delivering an alternating current. In the present example, the voltage is of the order of 115 V, with a delivered current of the order of 15 A, or of the order of 230 V, with a delivered current of the order of 16 A, at a frequency of the order of 50 kHz or more (high frequency suitable for small heating plates 9) or of the order of 10 kHz (low frequency allowing deeper heating to be obtained, more suitable for massive heating plates 9). The power in this example is 1.7 kVA (115 V) or 3.6 kVA (230 V). The heating plates 9 are suitable for induction heating and can be made of any material receptive to this heating method.

[0091] In a particularly advantageous example, the heating plates 9 are bimaterial plates. Figure 5 is a perspective sectional view of the stack 2. The heating plates 9 are thus made up of a structural envelope 13 in the thickness of which a susceptor insert 14 is positioned. The structural envelope 13 can be made from any material of suitable rigidity, including a non-magnetic material. The structural envelope 13 is chosen and dimensioned for its structural function, and possibly for clamping the stack 2, as well as resistance to the operating temperature, and resistance to the corresponding physicochemical stresses.

[0092] The susceptor insert 14, for its part, has the sole function of being the seat of heat production by the induction heating device. The susceptor insert 14 may therefore be made of a material that would have been unsuitable for direct placement in the thermal enclosure 4, for example due to a susceptibility to degradation by phenomena such as temperature or corrosion specific to the high-temperature environment of the electrochemical reactor. The material of the susceptor insert 14 is suitable for induction heating, and may have any melting point, or even a melting point lower than the operating temperature (without exceeding its Curie temperature), which is permitted by this arrangement where the susceptor insert 14 is hermetically contained in the structural envelope 13.

[0093] In the present example, the susceptor insert is preferably made of ferromagnetic material, or graphite.

[0094] The structural envelope 13 is therefore provided here to contain the susceptor insert 14 in a hermetic manner and preferably has good thermal conductivity for the transmission of heat to the stack 2.

[0095] In this embodiment, the structural casing 13 is made of 310 stainless steel alloy, which has good thermal conductivity. In this application, this alloy also has the particularity of having excellent resistance to oxidation and thermal corrosion. This alloy is, however, non-magnetic and will contribute little to the heating function. The latter is provided by the susceptor insert 14, which is adapted to combine the heating resulting from various phenomena such as eddy currents, hysteresis losses and magnetic viscosity, so as to significantly increase heat dissipation.

[0096] Preferably, the material of the susceptor insert 14 has a high Curie temperature, and preferably above the operating temperature. In one embodiment, the susceptor insert 14 is made of cobalt, a material having a Curie temperature of 1114.85°C. Certain high Curie temperature steels are also conceivable. According to another embodiment, the susceptor insert 14 is made of a cobalt-nickel alloy, with 50% cobalt, a material having a Curie temperature between 854°C and 877°C, suitable for an application whose operating temperatures are below these temperatures.

[0097] According to another embodiment, the susceptor insert 14 is made of graphite.

[0098] Figure 6 illustrates a heating plate 9 alone, seen in perspective. The heating plate 9 has a filling orifice 15 closed by a plug 16 (the plug 16 is illustrated, in exploded view, above the filling orifice 15). The plug 16 is for example made of the same metal as the structural casing 13 and closes the filling orifice 15 by welding.

[0099] According to one embodiment, the heating plates 9 can be produced by additive manufacturing, for example by powder bed fusion. The additive manufacturing is then based on the material constituting the structural envelope 13.

[0100] Figure 7 illustrates the heating plate 9 of Figure 6 seen in section. The heating plate 9 has a cavity 17 intended to receive the susceptor insert 14. In this example, the susceptor insert 14 is made of a fusible material.

[0101] After the production of the structural envelope 13 by additive manufacturing, the susceptor insert 14, after melting, is poured into the cavity 17 through the filling orifice 15, and the latter is then closed by the plug 16. The cavity 17 (and therefore the susceptor insert 14) is symmetrical with respect to the median plane of the heating plate 9, and equidistant with respect to the center thereof.

[0102] Alternatively, for all embodiments, the cavity 17 (and therefore the susceptor insert 14) may have other shapes, such as circular, rectangular, or star-shaped.

[0103] Figures 8 to 10 illustrate another embodiment of the heating plates 9 by additive manufacturing. In this example, the structural envelope 13 is devoid of a filling orifice.

[0104] Figure 8 illustrates a first step in the manufacture of the structural envelope 13, so as to produce a portion of structural envelope 13 (which is illustrated in Figure 8). This portion of structural envelope 13 has a thickness extending only up to a height which corresponds to the upper face of the susceptor insert 14, thus leaving an open cavity 17, a cavity which corresponds to the housing of the susceptor insert 14. The terms “height”, “thickness”, and “upper” refer here to the illustrations of Figures 8 to 10.

[0105] Additive manufacturing is then stopped.

[0106] With reference to Figure 9, a second step of the method consists of placing the susceptor insert 14 in the solid state in the cavity 17 thus formed.

[0107] Figure 10 illustrates the result of the installation of the susceptor insert: a flat surface is constituted by the upper surface of the structural envelope portion 13, and by the upper face of the susceptor insert 14 in position.

[0108] Alternatively, the susceptor insert 14 may have a thickness greater than the depth of the cavity 17. The method then comprises an additional step of machining the upper surface of the susceptor insert 14, to horizontally align the upper surface of the structural envelope portion 13 and the upper face of the susceptor insert 14.

[0109] Additive manufacturing is then resumed on this flat surface by forming a final thickness of the material constituting the structural envelope 13, by completely closing the cavity 17, until the complete part formed from the finished structural envelope 13 is obtained with the susceptor insert 14 contained in this structural envelope 13.

[0110] Alternative embodiments may be envisaged. For example, the heating plates 9 may be made by plates associated with bars or any other suitable geometry. At least one heating plate 9 is necessary, and the stack may further comprise a greater number of heating plates 9, for example distributed regularly within the stack, between the electrochemical cells 3. Such heating plates 9 arranged within the stack may also fulfill an interconnection plate function, thanks to channels.

Claims

CLAIMS 1. Solid oxide electrochemical reactor, comprising: - at least one stack (2) of solid oxide electrochemical cells (3) arranged in a thermal enclosure (4), each of these electrochemical cells (3) comprising a layer of solid electrolyte (5) arranged between two layers of electrodes (6, 7); - a device for heating said stack (2) to an operating temperature; characterized in that the heating device comprises: - at least one heating plate (9) arranged in the stack (2), a susceptor insert (14) being arranged at least partially in the heating plate (9); - at least one induction coil (10) arranged outside the stack (2), opposite the heating plate (9).

2. Solid oxide electrochemical reactor according to claim 1, characterized in that the susceptor insert (14) is arranged in the thickness of the heating plate (9).

3. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the heating plate (9) comprises a structural casing (13) enclosing the susceptor insert (14) in a hermetic manner.

4. Solid oxide electrochemical reactor according to claim 3, characterized in that the structural casing (13) comprises a cavity (17) for the susceptor insert (14), this cavity (17) opening outside the structural casing (13) via a filling orifice (15), the filling orifice (15) being closed by a plug (16) of the same material as the structural casing (13).

5. Solid oxide electrochemical reactor according to one of claims 3 or 4, characterized in that the structural casing (13) is made of non-magnetic material.

6. Solid oxide electrochemical reactor according to claim 5, characterized in that the structural casing (13) is made of stainless steel.

7. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the susceptor insert (14) has a curie temperature lower than said operating temperature.

8. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the susceptor insert (14) is made of ferromagnetic material.

9. Solid oxide electrochemical reactor according to claim 8, characterized in that the susceptor insert (14) is made of steel.

10. Solid oxide electrochemical reactor according to claim 8, characterized in that the susceptor insert (14) is made of cobalt.

11. Solid oxide electrochemical reactor according to claim 8, characterized in that the susceptor insert (14) is made of cobalt / nickel alloy.

12. Solid oxide electrochemical reactor according to one of claims 1 to 7, characterized in that said susceptor insert (14) is made of graphite.

13. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the heating plate (9) comprises a clamping device (11) for the stack (2).

14. Solid oxide electrochemical reactor according to claim 13, characterized in that it comprises two heating plates (9), at two ends of the stack (2), and the clamping device (11) is adapted to clamp the stack (2) between the two heating plates (9).

15. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the induction coil (10) is a flat coil arranged opposite the heating plate (9).

16. Solid oxide electrochemical reactor according to claim 15, characterized in that the induction coil (10) extends in a plane substantially parallel to the heating plate (9).

17. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the induction coil (10) is arranged in the thickness of the thermal enclosure (4).

18. Solid oxide electrochemical reactor according to claim 17, characterized in that the thermal enclosure (4) comprises a wall made of thermally insulating material, with a housing (19) for the induction coil (10).

19. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the distance between the induction coil (10) and the heating plate (9) is substantially between 30 and 80 mm.

20. Solid oxide electrochemical reactor according to one of the preceding claims, characterized in that the induction coil (10) is formed from a tubular conductor (12), and in that the heating device comprises a device for cooling the induction coil (10) by circulation of a heat transfer fluid in the tubular conductor (12).

21. Method for manufacturing an electrochemical reactor according to claim 4, characterized in that it comprises: a step of producing by additive manufacturing the heating plate (9) with said cavity (17) and the filling orifice (15); a step of pouring a molten susceptor material through the filling orifice (15); and a step of closing the filling orifice (15) with said plug (16).

22. Method for manufacturing an electrochemical reactor according to claim 3, characterized in that it comprises: a step of producing by additive manufacturing a portion of the structural envelope (13) with a cavity (17) corresponding to the housing of the susceptor insert (14); stopping the additive manufacturing and placing the susceptor insert (14) in the cavity (17); and a step of resuming the additive manufacturing by forming a final thickness of the structural envelope (13), closing the cavity (17).

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