Solid oxide electrochemical system with built-in heating means

Abstract

The present invention relates to an electrochemical system including an electrochemical device. The electrochemical device includes a stack of n (n is an integer equal to or greater than 1) solid oxide electrochemical cells, at least n-1 interconnect plates interposed between the electrochemical cells, a means for supplying gas to the electrochemical cells, a means for recovering gas produced in the electrochemical cells, and a means for electrically connecting the system to the outside. The electrochemical device also includes a heating means (H) integrated into the stack, the heating means (H) including an electrical conductor (2) housed in clamping plates (S1, S1).

Description

[Technical Field]

[0001] The present invention relates to electrochemical systems that include solid oxide electrochemical cells operating at high temperatures. [Background technology]

[0002] The system may be implemented for high temperature electrolysis and include a stack of solid oxide electrolysis cells or SOECs, or may be implemented as a fuel cell and include a stack of solid oxide fuel cells or SOFCs.

[0003] Such a system includes a stack of electrochemical cells sandwiched between two clamping plates.

[0004] Each cell contains an electrolyte between two electrodes. Interconnect plates are placed between the cells to provide electrical connections between the cells. The interconnect plates also provide gas supply to the cells and collect the gas produced by each cell.

[0005] In operation, the anode and cathode are the sites of electrochemical reactions, while the electrolyte allows for the transport of ions from the cathode to the anode or vice versa, depending on whether the electrochemical device is operating in electrolysis mode or fuel cell mode.

[0006] Thus, in electrolyzer mode, the cathode compartment is supplied with water vapor, allowing the evacuation of the water reduction products, especially hydrogen, while the anode compartment is supplied with O, which migrates from the cathode to the anode. 2- The dioxygen produced by the oxidation of the ions is ensured to be discharged via the exhaust gas.

[0007] The mechanism of water vapor electrolysis (SOEC mode) using the unit electrochemical cell is explained below. During this electrolysis, a current is supplied to the unit electrochemical cell from the cathode to the anode. The water vapor discharged from the cathode compartment is reduced by the influence of the current through the following half-reaction: 2H2O+4e - →2H2+2O 2-

[0008] The dihydrogen produced during this reaction is released, and the O produced during the reduction 2- The ions migrate from the cathode through the electrolyte to the anode where they are oxidized to dioxygen via the following half-reaction: 2O 2- →O2+4e -

[0009] The dioxygen thus produced is carried away by the drain gas flowing through the anode compartment.

[0010] The electrolysis of water vapor is based on the following reaction: 2H2O → 2H2+O 2

[0011] In fuel cell mode ("SOFC"), air is injected into the cathode compartment and O 2- These ions migrate to the anode and react with dihydrogen flowing into the anode compartment to produce water.

[0012] In fuel cell mode of operation, an electric current is generated.

[0013] The clamping plates exert a clamping force on the stack to ensure good electrical contact between the interconnect plates and the cells and a tight seal on the stack.

[0014] The operating temperatures of SOEC / SOFC systems are typically between 600°C and 1000°C. These temperatures are achieved by placing the stack in a high-power oven. The oven includes a housing and, for example, an electrical resistor mounted inside the housing wall. This gives the oven a certain overall size. Heat transfer between the electrical resistor and the stack occurs via convection and radiation. Instrumentation is installed in the space between the oven and the device to monitor and regulate the temperature.

[0015] Thus, the hydrogen production or power generation system includes an oven and an electrochemical device, and the overall size of the system is relatively large and difficult to handle.

[0016] Furthermore, for safety reasons, gas flushing is performed inside the oven, which disrupts convective transfer.Furthermore, radiative heat transfer is dependent on the size of the enclosure; the larger the enclosure, the greater the impact on radiative heat transfer.

[0017] Patent Document 1 describes an example of an electrochemical device that includes a stack of solid oxide cells held together by a "plug-and-play" type clamping system that can be easily connected to a gas supply and recovery circuit. The clamping system is designed to ensure a substantially constant clamping level even with temperature changes. The electrochemical device is placed in an oven. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] International Publication No. 2017 / 102657 Summary of the Invention [Problem to be solved by the invention]

[0019] It is therefore an object of the present invention to provide an electrochemical system including a solid oxide electrochemical cell that operates at high temperatures without the drawbacks of prior art systems. [Means for solving the problem]

[0020] The above objects are achieved by a system including an electrochemical device comprising a stack of solid oxide electrochemical cells, an interconnect plate interposed between the cells, and a heating means integrated into the stack, the heating means including an electrical conductor, for example, an electrical conductor disposed within or in contact with a clamping plate for inputting thermal energy to the device.

[0021] The electrochemical system no longer requires oven packaging, thereby reducing its overall size, making it easier to transport and use, and further simplifying the system by allowing instrumentation for temperature control to be integrated into the stack.

[0022] Furthermore, by integrating the heating means into the electrochemical device, the drawbacks associated with heat transfer between the walls of the oven housing and the stack no longer occur, since heating is achieved directly by conduction through the dense material.

[0023] Furthermore, such a heating means has improved responsiveness to the temperature setpoint set in the device.

[0024] In a highly advantageous embodiment, the electrochemical system includes an insulated enclosure defining an insulated space for receiving an electrochemical device.

[0025] Thus, heat leakage is significantly reduced, heating of the device is more uniform, and there is much better thermal uniformity in the stack between the top and bottom plates, and therefore throughout the stack.

[0026] Furthermore, the reduced heat loss due to the presence of the enclosure allows the setpoint applied to the heating means to be closer to the heating target of the stack, reducing the power supplied to the device.

[0027] The insulating enclosure is advantageously shaped to fit as close as possible to the outer surface of the stack, which can further limit radiation losses.

[0028] One subject of the present invention is therefore an electrochemical system comprising at least one electrochemical device, said electrochemical device comprising a stack of n solid oxide electrochemical cells, n being an integer greater than or equal to 1, and further comprising at least n-1 interconnect plates interposed between said electrochemical cells, means for supplying gas to said electrochemical cells, means for recovering gas produced by said electrochemical cells and means for electrically connecting said system to the outside, said electrochemical device also comprising heating means integrated in said stack, said heating means having a Joule effect.

[0029] The n electrochemical cells each comprise a lateral cross-sectional area S taken along a direction perpendicular to the stack direction. Preferably, the heating means defines a heating surface area at least equal to the lateral cross-sectional area S of the electrochemical cell.

[0030] Preferably, said heating means are inserted in at least one plate, called a heating plate, placed in or on said stack.

[0031] In an exemplary embodiment, the heating means includes at least one electrical conductor housed in the at least one heating plate.

[0032] For example, the at least one hot plate may include recesses formed in a larger surface area thereof in which the electrical conductors are received and held in place within the recesses, for example by solder. Alternatively, the electrical conductors may be pressed into machined grooves.

[0033] In another exemplary embodiment, said heating means comprises at least one electric heating element mounted in a bore of said hotplate, advantageously at a side edge of said hotplate.

[0034] The at least one heating plate may be arranged at an end of the stack in the direction of the stack through which the gas supply means passes.

[0035] In an advantageous embodiment, at least one heating plate comprises temperature measurement means, which may comprise a sensor configured to measure the temperature of the electrical conductor or the electric heating element, and a sensor configured to measure the temperature of the heating plate.

[0036] The electrochemical system may advantageously include two clamping plates, each at one end of the stack and arranged in the direction of the stack, and means for applying a clamping force to the n cells and n-1 interconnects in cooperation with the plates.

[0037] According to an additional feature, the heating means are inserted into at least two heating plates.

[0038] In one exemplary embodiment, said at least one heating plate may advantageously be formed by a clamping plate.

[0039] The heating means can be integrated into one or more of the clamping plates, allowing for easy adaptation to existing devices.

[0040] In another exemplary embodiment, the at least one heating plate is a spacer plate attached to two cells.

[0041] In another exemplary embodiment, said at least one heating plate is pressed against the clamping plate, advantageously on its outer surface.

[0042] The electrochemical system may advantageously include a thermally insulated housing that defines an interior space for receiving the electrochemical device and insulates the electrochemical device from the outside. For example, the housing may include a hearth, a side wall, and a top wall. The electrical connection means, gas supply means, and gas recovery means can pass through the hearth.

[0043] The present invention will be better understood based on the following description and the accompanying drawings. [Brief explanation of the drawings]

[0044] [Figure 1] 1 is an exploded view of an electrochemical system illustrating the principles of the present invention. [Figure 2] 1 is a perspective view of an electrochemical system according to an illustrative embodiment. [Figure 3A] 3 is a perspective view of a clamp plate mounted in the system of FIG. 2, shown alone. [Figure 3B] 3B is a detailed cross-sectional view of the clamping plate of FIG. 3A at the electrical conductor. FIG. [Figure 4A] 3 is a perspective view of an alternative clamping plate that can be implemented in the system of FIG. 2. [Figure 4B] 3 is a perspective view of an alternative clamping plate that can be implemented in the system of FIG. 2. [Figure 5] 3 is a perspective view of a clamping plate according to another exemplary embodiment that may be implemented in the system of FIG. 2. [Figure 6] FIG. 10 is a perspective view of an electrochemical system according to another exemplary embodiment, in which the heating means is attached to the outer clamping plate. [Figure 7A] 7A and 7B are different schematic diagrams of the heating means of the system of FIG. 6. [Figure 7B] 7A and 7B are different schematic diagrams of the heating means of the system of FIG. 6. [Figure 7C] 7A and 7B are different schematic diagrams of the heating means of the system of FIG. 6. [Figure 8] 1 is a schematic diagram of an electrochemical installation implementing a system according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0045] In FIG. 1 there is seen an exploded view of an exemplary embodiment of an electrochemical system according to the present invention.

[0046] The electrochemical system includes an electrochemical device D1 implemented as a high temperature electrolysis ("SOEC" mode) or a fuel cell ("SOFC" mode).

[0047] The electrochemical device D1 comprises a stack of solid oxide electrochemical cells.

[0048] The stack comprises multiple unit electrochemical cells CL, each formed by a cathode, an anode, and an electrolyte disposed between the anode and cathode. The electrolyte is a solid, dense, ion-conducting material, while the anode and cathode are porous layers.

[0049] The stack further includes an interconnect plate or interconnector I disposed between two consecutive unit cells and providing an electrical connection between the anode of one unit cell and the cathode of an adjacent unit cell. The interconnector I provides a series connection of the unit cells.

[0050] One stack can include one cell to several hundred cells, preferably 25 to 75 cells.

[0051] The intermediate interconnects also delimit fluid compartments at the surfaces of the electrodes they contact.

[0052] The face of the intermediate interconnector I in contact with the anode of a unit electrochemical cell CL defines a compartment called the anode compartment, and the face of the interconnector I in contact with the cathode of a unit electrochemical cell CL defines a compartment called the cathode compartment.

[0053] The anode and cathode compartments are capable of discharging and recovering the gas, respectively.

[0054] For example, in the case of water electrolysis, the cathode compartment ensures the supply of water vapor to the cathode and the discharge of the hydrogen produced, while the anode compartment ensures the flow of drain gas and discharges the oxygen produced at the anode.

[0055] The electrochemical device may include end plates P disposed on either side of the stack. The end plates are electrically conductive.

[0056] The device also includes a tube (not shown) for discharging the gas and a tube for collecting the gas.

[0057] In the example presented, the electrochemical device D1 also comprises a clamping system S1, S2, which comprises two clamping plates, respectively called a first or upper clamping plate S1 and a second or lower clamping plate S2, arranged on either side of the stack in the direction of the stack and for exerting a clamping force on the stack by means of tie rods T.

[0058] According to this configuration, each end plate P is electrically insulated from the adjacent clamp plate by inserting an electrically insulating plate M, for example made of mica, between each clamp plate and each end plate.

[0059] The tie rods T are formed, for example, by clamping rods passing through clamping plates and fitted with nuts at their ends. These means are described in this respect in French patent no. 3045215.

[0060] Advantageously, the clamping plates S1, S2 may be made of stainless steel, very advantageously made of a fire-resistant austenitic steel, for example of type AISI 310S, which can withstand temperatures between 20°C and 800°C, 18.5.10 -6The thermal expansion coefficient of this steel is 0.15. Furthermore, this steel has good mechanical strength up to 1000 °C. The tie rods are made of nickel-based superalloys, for example of the Inconel 625 type.

[0061] This combination of materials makes it possible to compensate for the difference in expansion between the clamp rod and the electrochemical cell due to the large expansion of the clamp plate. Advantageously, a washer made of the same material as the clamp plate is inserted between the clamp plate and the nut.

[0062] One and / or both of the clamping plates S1, S2 are provided with at least one gas flow duct that allows gas to flow from a gas inlet to a gas outlet for supplying gas to and evacuating gas from the solid oxide stack.

[0063] The gas inlet and gas outlet are located on the large surface area faces of both clamping plates S1 and S2, respectively.

[0064] The electrochemical device also comprises heating means H integrated into the stack. In Figure 1 these means H are represented diagrammatically.

[0065] Here, "integral heating means" means heating means that are in direct mechanical contact with the stack. These heating means are located on and / or within the stack. The heating means may be attached to an already existing stack element or to an element that is being added to the stack.

[0066] The heating means H1 are electric joule heating means. These heating means include one or more electrically conductive cables or cords 2 that are integrated into the stack and generate heat by dissipation. In the following description, the terms "cable," "electric cable," "heating cable," or "conductor" refer to the electrically conductive cable forming the heating means. For example, the heating cable includes a heating core with mineral insulation, MgO (96-99%), under an Inconel 600 sheath and integrated cold terminations. The heating core has, for example, a diameter of 2.0 mm ± 0.05 mm over a length of 6.5 m ± 5% and an internal resistance of 7.0 Ω / m ± 10%. An exemplary embodiment of a practical electrochemical device D2 can be seen in Figures 2, 3A, and 3B. In this example, the heating means H1 is arranged through the thickness of one or both clamping plates S101 and S102. Advantageously, the heating means H1 is arranged on both clamping plates to ensure uniform heating of the stack.

[0067] The clamping plates are made of a material capable of conducting heat to the stack, the material preferably having a good thermal conductivity, preferably at least equal to 10 W / mK. AISI 310S steel advantageously has a good thermal conductivity of 15 W / mK at 20°C and 19 W / mK at 500°C.

[0068] In this example, as shown in Figure 3B, a recess 4 is formed in one of the large surface area faces of the clamping plate S101, the depth of which is sufficient to receive the electrical cable 2. Preferably, the depth of the recess 4 is sufficient so that the cable 2 does not protrude from the plate. The cable is fixed in the recess 4 by adding a material, such as solder 5, manufactured, for example, under vacuum. Preferably, the material of the solder is the same as the material of the clamping plate, to avoid the risk of differential expansion.

[0069] Preferably, the solder is placed on the stack side, thus placing the heating zone as close as possible to the stack.

[0070] Alternatively, the cable is pressed into a machined groove in the plate.

[0071] In this example, the conductors are arranged in the form of a square spiral.

[0072] It is highly advantageous if the electrical cables are distributed over a surface area corresponding to the surface area of ​​the electrochemical cells in order to optimize heating of the device. In the example presented, the clamping plate S101 comprises a square-shaped main part 6 and branches 8 protruding from each side of the main part for threading tie rods therethrough. The electrical cables cover the entire surface of the main part almost to the edges. In this example, the electrical cables are distributed evenly over the surface, ensuring even heating over the entire surface of the stack.

[0073] The cable connection ends 2.1, 2.2 exit laterally from the clamping plate and are electrically connected to the rest of the system.

[0074] The implementation of a Joule heating means has the advantage that the thermal energy generated can be easily controlled. By integrating it as close as possible to the cells, the actual energy input to the stack can be controlled. It also reduces the overall size. Furthermore, integrating the cable(s) into the clamping plate allows for the overall size of the electrochemical device to remain unchanged, making it possible to replace devices already installed.

[0075] Furthermore, electrical heating means allow temperatures to be reached that are higher than the operating temperature of the stack, which allows greater freedom in the placement of the device in the environment.

[0076] In Figures 4A and 4B, variants of the clamping plate S201 can be seen in which the electric cables 2 have different distributions.

[0077] Any other distribution of the electrical cables is also conceivable.

[0078] In heat absorption operation, the greatest heat loss occurs in the center of the stack, and preferably the plates have a high density of conductors in the center of the plates to provide a higher thermal mass at the center of the plates compared to the edges of the plates.

[0079] The recesses are made, for example, by machining.

[0080] For example, the clamp plate has an in-plane dimension of several hundred mm, for example, 200 mm×200 mm, and a thickness of 1 to several tens of mm, for example, 10 mm.

[0081] In the example presented, only one electrical cable is implemented per plate, which simplifies the connection to the power supply. However, it is also possible to envisage multiple cables per plate, distributed in one or more planes. The implementation of multiple cables has the advantage that heat can still be supplied to the stack in case of a cable failure, especially since the clamping plates cannot generally be removed, since the loads acting on them via the tie rods cannot be undone without rendering the device inoperable.

[0082] Advantageously, one or more temperature sensors 10, 11, for example the thermocouples shown in Figure 4A, are arranged on each clamping plate. Preferably, two temperature sensors are used: a safety temperature sensor 10, which is arranged as close as possible to the heating cable in order to control the temperature of the cable and avoid overheating or deterioration, and a regulating temperature sensor 11, which is arranged to measure the temperature of the plate, the regulating sensor being arranged further away from the heating cable, for example a few millimeters away.

[0083] In FIG. 5, another exemplary embodiment of a clamping plate S301 can be seen, which is diagrammatically represented and equipped with a heating means H2. The heating means H2 comprise conductive elements in the form of fingers or pins 12, which are inserted laterally into the clamping plate as shown. The plate includes recesses 14, e.g. blind bores, at its side edges, in which heat-dissipating conductive elements are attached. Preferably, the pins or fingers are evenly distributed over the entire periphery of the plate. Preferably, the fingers are press-fit into the recesses 14 to ensure good thermal contact between the fingers and the plate and reduce heat loss. As a variant, it can be envisaged, particularly for the upper clamping plate, for at least some of the fingers to be arranged perpendicular to the mid-plane of the clamping plate.

[0084] The heating means can be integrated into one or more of the clamping plates, allowing for easy adaptation to existing devices.

[0085] The intermediate plane of the clamping plate is the plane to which the larger surface area faces of the clamping plate are substantially parallel.

[0086] In Figure 6, another exemplary embodiment of an electrochemical device D3 can be seen, in which heating means H3 are attached to the clamping plate at its outer side. The heating means comprises at least one heating plate 16, which is presented in Figures 7A-7C.

[0087] The heating plate 16 is manufactured in a manner similar to that of the clamping plate of Figures 2, 3A, and 3B. The heating plate 16 includes a recess 16.1 formed in one of its major large-area faces and an electrical cable 16.2, represented by a dotted line, disposed within the recess 16.1, with solder 16.3 applied to the cable in the recess 16.1 to secure the cable within the recess. In Figure 7B, the solder has not yet been applied.

[0088] The plate 16 thus formed can then be mounted in direct contact with the outer surface of the clamping plate S1. Preferably, the contact surface has very good flatness to ensure very good heat transfer between the heating plate 16 and the clamping plate S2. For example, the heating plate can be brought into contact with the clamping plate, benefiting from the heating means integrated into the stack, without being permanently fixed and easily removable. Alternatively, a layer of ductile material with good thermal conductivity, such as gold paste, can be inserted between the clamping plate and the heating plate to improve the thermal contact between them and compensate for any flatness defects.

[0089] Alternatively, the heating plate may have heating fingers or pins, as in the example of Figure 5. The fingers or pins may be attached via the side edges and / or the main outer surface of the heating plate.

[0090] The implementation of one or more heating plates 16 attached to the clamping plate allows for the installation of already fabricated electrochemical devices, and also accommodates cases where it is not possible to remove the clamping plate and replace it with an integral heating clamping plate or to introduce a spacer heating plate.

[0091] In FIG. 6 the gas supply and recovery ducts C and the cables 15 for electrical connection to the end plates T can be seen.

[0092] Alternatively, the heating means may be integrated into the stack as an additional plate. For example, the heating means may comprise one or more spacer plates with integrated heating cables. This or these plates are positioned between the clamping plates and the end plates. Preferably, two spacer plates are provided, one between the upper clamping plate and the upper end plate, and one between the lower clamping plate and the lower end plate.

[0093] According to another variant, a spacer plate(s) is / are placed between each two unit electrochemical cells. By inserting the heating spacer plates, the vertical thermal gradient within the stack can be reduced. In this variant, the spacer plates replace the interconnects or external electrical connection means allow electrical connection between the cells.

[0094] The heating plate may advantageously be equipped with one or more safety and / or regulatory temperature sensors.

[0095] The thermocouples are advantageously located on the heating plate(s) 16 or on the spacer plate(s).

[0096] Depending on the electrochemical device fabricated, the clamping plates may be omitted if no clamping force needs to be applied in the direction of the stack.

[0097] It will be understood that the different examples of Figures 1-6 may be combined. For example, the heating means may include a conductor or conductors in only one of the clamping plates and the spacer plate. Alternatively, the heating means may include the heating plate 16 and the clamping plate with the heating conductor incorporated therein.

[0098] Preferably, the electrochemical device is placed in a housing to reduce energy losses, especially heat losses, and optimize operation of the device, for example, the walls of the housing comprise one or more fibrous insulating materials including SiO2, CaO, and MgO, or one or more lightweight concrete-type materials.

[0099] In FIG. 8, a schematic representation of an installation can be seen, including an electrochemical device according to the invention, for example device D2, arranged in a housing 17, the housing being represented in cross section.

[0100] The enclosure includes a hearth 18 in which the electrochemical device is placed, side walls 20, and a top wall 22. The walls and hearth define an enclosed volume that insulates the electrochemical device from the external environment.

[0101] The housing, particularly the side wall 20 and top wall 22, may be made integrally or from multiple parts assembled together. The housing is provided with openings 24 for the passage of tubing and electrical connectors. The clearances around the openings and between the tubing and connectors are advantageously filled with thermally insulating material. It is highly advantageous if the fluid and electrical connections are made through the hearth 18, further reducing heat leakage.

[0102] Preferably, the inner periphery of the housing corresponds to the outer shape of the electrochemical device and defines a reduced clearance with the outer surface of the device, which allows the heat radiated from the electrochemical device to be reflected more effectively by the inner wall of the housing, thereby allowing the implementation of heating means with reduced power compared to those normally used in this type of application.

[0103] Furthermore, the combination of an integrated electric heating means and an electrically insulated housing contributes to reducing thermal gradients in the stack direction, uniformizing the temperature within the electrochemical device and improving the efficiency of the electrochemical device.

[0104] This temperature equalization allows a heating setpoint to be applied to the integral outer conductor that is closer to the desired heating temperature of the stack, which may reduce the risk of overheating and damaging elements of the device, especially those at the top of the stack.

[0105] It is also possible to provide a reflective material on the inner wall of the housing.

[0106] Preferably, a free space is maintained between the electrochemical device and the inner wall of the housing so that leaks on the stack can be detected. Typically, the housing is purged with air to dilute and expel any possible hydrogen leaks from the stack. Furthermore, it is preferable to avoid contact between the housing and the stack to reduce the risk of short circuits.

[0107] One or more sensors may also be mounted on the housing or positioned in the space between the housing and the electrochemical device, such as a temperature sensor for regulating the temperature of the device, or a gas sensor for detecting leaks in the device.

[0108] The electrochemical device according to the invention has the advantage of being very compact, since it does not need to be placed inside an oven. Furthermore, it is very easy to use, since it can be easily connected to four gas supply and recovery ducts, an integrated heating system and a power supply for the end plates. Therefore, the device is of the "plug and play" type.

[0109] When the device is housed in a housing, the housing is advantageously compact because it conforms to the shape of the device, which can be easily realized. The housing can be assembled around the device, unlike an oven that has an electrical resistor on its inner wall. Furthermore, the absence of an electrical resistor allows for a thinner wall thickness.

[0110] The heating means are controlled by a central device, for example a computer, based on measurements, for example thermocouples and temperature setpoint(s).

[0111] If the heating means are integrated in at least two different locations in the stack, the system can have a very large modularity in heating control, and in fact it can be envisaged to control them together or separately, adjusting the heat input depending on the location in the stack and / or the time of operation, and allowing a differentiated management of the heating cables.

[0112] For example, in the case of equipment installed in a thermally insulated enclosure, heat accumulates in the upper part of the enclosure, so the upper part of the stack can be maintained at a predetermined temperature with less energy input. It is also possible to control the heating means to input more heat to the lower part of the stack.

[0113] For example, in a system where two clamping plates with heating wires are placed in an enclosure, the heating wires can be activated as follows. At the beginning of the operating cycle, heat is generated in both clamping plates until the operating temperature and steady state operation are reached. - During steady-state operation, temperature maintenance can then be ensured by simply heating one of the clamping plates, preferably the clamping plate through which the gas supply tube passes, which has a temperature lower than the operating temperature. In this way, the integrated heating means also provides a means for heating the gas.

[0114] If the gas is supplied from the upper plate, the heating wires in the upper plate can be permanently activated, but only for preheating the gas, the temperature maintenance being ensured by the conductive wires in the lower clamping plate.

[0115] For example, in the case of operation of a system for producing hydrogen (SOEC), the operation is endothermic and heat input is provided during the entire operation of the system, but heat input during steady state operation can be provided by heating means integrated into the lower clamping plate.

[0116] Additionally, when the system is operating to generate heat, the heating wires in both clamping plates can be heated to reach operating temperature, after which only the lower clamping plate can be permanently heated to heat the gas. [Explanation of symbols]

[0117] 2. Conductors 4 recess 5. Solder 10, 11 Sensor 12 Electric heating element 14 bore 16.1 Recesses 16.3 Solder 17 Insulated housing 18 Hearthstone 20 side wall 22 Upper Wall CL unit electrochemical cell D1 Electrochemical Devices I Interconnector M Electrical insulating board P end plate T tie rod S1, S2, S101, S102, S201, S301 clamp plate H, H1, H2, H3 heating means

Claims

1. 1. An electrochemical system having at least one electrochemical device, comprising: The electrochemical device comprises: a stack of n solid oxide electrochemical cells (n is an integer of 1 or greater); at least n-1 interconnect plates interposed between the electrochemical cells; a means for supplying gas to the electrochemical cell; means for collecting gas produced in the electrochemical cell; means for electrically connecting the system to the outside world; heating means (H, H1, H2, H3) integrated into said stack, said heating means (H, H1, H2, H3) having a Joule effect, said heating means (H1, H2) being inserted into at least one plate, called a heating plate, located in or on said stack; two clamping plates (S1, S2, S101, S102, S201, S301) each arranged at one end of the stack in the direction of the stack; A tie rod (T) that passes through the two clamp plates and applies a clamping force to the n cells and the n-1 interconnects; Equipped with the heating means is arranged so that heating of the stack occurs through at least a portion of at least one clamping plate; The electrochemical system wherein the at least one heating plate is formed by a clamping plate or is in contact with an outer surface of the at least one clamping plate.

2. The n electrochemical cells each comprise a lateral cross-sectional area S along a direction perpendicular to the stack direction; said heating means (H, H1, H2, H3) defining a heating surface area at least equal to said lateral cross-sectional area S of said electrochemical cell; The electrochemical system of claim 1 .

3. The heating means (H1) comprises at least one conductor cable (2) housed in the at least one heating plate.

3. The electrochemical system according to claim 1 or 2.

4. The at least one heating plate has a recess (4) formed in a surface of a larger surface area, The conductor cable (2) is accommodated in the recess (4) and is maintained in a fixed state within the recess (4), or 4. The electrochemical system of claim 3, wherein the at least one heating plate includes machined grooves into which the conductor cables (2) are pressed.

5. 5. The electrochemical system of claim 4, wherein the conductor cable (2) is held fixed in the recess (4) by solder (5).

6. The heating means comprises an electric heating element (12) in the form of at least one finger or pin mounted in a hole (14) in the heating plate; The electrochemical system of claim 1 .

7. 7. The electrochemical system of claim 6, wherein the at least one electric heating element (12) is mounted in a hole (14) in a side edge of the heating plate.

8. the at least one heating plate is provided with a temperature measuring means; 8. An electrochemical system according to any one of claims 1 to 7.

9. The heating means (H1) comprises at least one conductor cable (2) housed in the at least one heating plate and at least one electric heating element (12) in the form of a finger or pin attached to a hole (14) in the heating plate; the at least one heating plate is provided with a temperature measuring means; The temperature measuring means a sensor (10) configured to measure the temperature of the electrical conductor cable (2) or the electric heating element (12); a sensor (11) configured to measure the temperature of the heating plate; Equipped with The electrochemical system of claim 1 .

10. The electrochemical device is provided with a thermally insulated housing (17) that defines an internal space for receiving the electrochemical device and insulates the electrochemical device from the outside.

10. An electrochemical system according to any one of claims 1 to 9.

11. The housing (17) comprises a hearth (18), a side wall (20), and an upper wall (22); the electrical connection means, the gas supply means, and the gas recovery means pass through the hearth; The electrochemical system of claim 10.

Images