Pressurized electrochemical reactor

Abstract

Title: Pressurized Electrochemical Reactor The invention relates to an electrochemical reactor (1), configured to receive a stack (10), the reactor comprising a support plate (22), the stack being positioned in contact with the support plate, characterized in that the reactor further comprises a dome (30), having an internal volume (Vint), intended to receive the stack, of liquid glass frit (40) having a volume (Vl) and an upper face called the free surface (41) and configured to cover the stack, the internal volume further comprising a covering gas (42) positioned in contact with the free surface of the liquid frit volume, the covering gas being configured to be pressurized by a module to a clamping pressure (Ps), the latter being configured so as to maintain the stack in compression on the support plate under a mechanical force proportional to the clamping pressure. Figure for the abstract: Fig. 5

Description

Title of the invention: Electrochemical pressure reactor technical field

[0001] The present invention relates to the field of solid oxide fuel cells (SOFCs) and that of high-temperature water electrolysis, also using solid oxides (SOECs). More specifically, the invention relates to maintaining a stack used in SOFC and SOEC type fuel cells. STATE OF THE ART

[0002] Gas and / or electricity production systems using solid oxide fuel cells fall under two main technological categories: tubular systems and planar systems. Within planar technologies, SOEC (Solid Oxide Electrolysis Cells) or SOFC (Solid Oxide Fuel Cells) systems consist of an alternating stack of an active part, the electrochemical cell, typically made of ceramic, and metallic bipolar plates.

[0003] The stack thus comprises a plurality of thin interconnector plates mounted between two rigid end plates that are subjected to a voltage differential. In order to ensure the electrical continuity of many layers of these structures and the power supply to each of the cells mounted in series in the stack, it is necessary to apply a compressive force to the stack to initiate and maintain contact areas. A compression defect, limiting the current flow in the multilayer structure, results in increased ohmic losses in the stack and heating. During operation, ensuring proper compression of the stack is an essential prerequisite for its correct functioning.

[0004] In current industrial concepts, modules grouping several stacks mounted in the same heating chamber are generally clamped by external mechanical devices capable of maintaining a quasi-constant compression force while accommodating the thermal expansions of the components.

[0005] These external mechanical devices can be attached to the stack. This is called a self-locking assembly, and it allows the stack to be held compressed between two thick flanges connected by threaded rods. However, self-locking assemblies have technical limitations for large stacks.

[0006] These external mechanical devices can also be located remotely. The stack is then mounted on a rigid base resting on the floor of the heating chamber's furnace and is compressed by a crossbar supported by an external device. External clamping devices present numerous disadvantages in terms of integration, particularly when it becomes necessary to locate them outside the heating chambers.

[0007] Furthermore, external devices maintaining a constant force must incorporate elastic elements to accommodate geometric variations during thermal cycles. Integrating these elastic elements within heated enclosures is challenging. Therefore, they must be made of special alloys compatible with the operating conditions of the stacks. Consequently, applying a compressive force to a stack or a module comprising a plurality of stacks positioned within a heated enclosure is technically very complex due to the high operating temperatures.

[0008] An objective of the invention is to propose a solution to simplify the application of this compression force on a stack positioned in a heated chamber.

[0009] Other objectives can be achieved by this solution. SUMMARY

[0010] To achieve this objective, according to one embodiment, an electrochemical reactor is provided, configured to receive a stack having a first face and a second face opposite the first face and at least one external wall connecting the first face to the second face and configured to operate at an operating temperature, the reactor comprising: • a support configured to ensure the passage of the gases supplying the stack, the support comprising a bearing plate, the stack being positioned so that its second face is in contact with the bearing plate, characterized in that the reactor further comprises: • a closing dome, having an internal volume, designed to receive the stack and to be hermetically fixed to the support, • of glass frit having a volume of glass frit and positioned in the internal volume, and configured to undergo a phase transition at the operating temperature of the stack so as to form liquid glass frit having a volume of liquid glass frit and further configured to cover the stack, the volume of liquid glass frit being less than the internal volume and having a top face called the free surface, the internal volume further comprising a gas called a covering gas, the covering gas being positioned above and in contact with the free surface of the liquid frit volume, the covering gas being configured to be pressurized to a clamping pressure by a pressurizing module, the clamping pressure being configured so as to maintain the stack on the support plate in compression under a mechanical force proportional to the clamping pressure.

[0011] Thus, the invention makes it possible to maintain by hydrostatic effect the pressure exerted on the free face of the glass and is transmitted integrally and homogeneously on the terminal plate of the stack and this without the need for mechanical components.

[0012] Advantageously, the compressive force transmitted to the stack is adjustable by varying the internal pressure. The proposed device thus constitutes an active system for continuously adjusting the compressive force according to the internal pressure of the stack.

[0013] Furthermore, another advantage of the concept is that it ensures a very high level of sealing for the stack. Indeed, the external walls of the stack, the interface between the stack and its manifold support plate, and the interface between the dome and the support plate are all immersed in the glass bath. Therefore, it is no longer gas tightness that needs to be ensured by gaskets and seals, but rather a tightness to glass (a viscous liquid). The only gas tightness required is that of the plug welded to the dome. In terms of leakage at the stack level, since the feed gases are at a lower pressure than the external fluid, they cannot escape due to the back pressure.Crack-type defects in seals, which can be responsible for gas leaks in a stack, have geometries (micrometric dimensions, high tortuosity, capillary effect, very high viscosity) that do not allow the passage of a viscous fluid such as glass.

[0014] According to another aspect, a method for pressurizing an electrochemical reactor as described above is provided, in which the method comprises: • Positioning the stack on the support, • Positioning and securing the dome to the support so as to surround the stack, • filling the dome with glass frit through an opening, • a stopper fixed in the opening so as to make the internal volume of the dome airtight, • an increase in temperature within the reactor to reach the operating temperature, • pressurization of the reactor up to a clamping pressure by the pressurization module.

[0015] Thus, the implementation of this compression is facilitated and quick to implement. BRIEF DESCRIPTION OF THE FIGURES

[0016] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0017] [Fig.1A] Figures IA and IB represent a support according to an embodiment of the invention.

[0018] [Fig.1B]

[0019] [Fig.2A] Figures 2A and 2B represent a dome according to one embodiment of the invention.

[0020] [Fig.2B]

[0021] [Fig.3A] Figures 3A and 3B represent the stack positioned on the support according to an embodiment of the invention.

[0022] [Fig.3B]

[0023] [Fig.4A] Figures 4A and 4B represent the closure of the dome on the support according to an embodiment of the invention.

[0024] [Fig.4B]

[0025] [Fig.5A] Figures 5A to 5D represent the insertion of the glass frit and the pressurization of the device according to an embodiment of the invention.

[0026] [Fig.5B]

[0027] [Fig.5C]

[0028] [Fig.5D]

[0029] [Fig.6A] Figures 6A and 6B represent another embodiment of the invention.

[0030] [Fig.6B]

[0031] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0032] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0033] According to one example, the clamping pressure is between 500 hPa and 200 kPa. These low pressure values ​​(Ps) make it possible to consider the construction of a pressurized enclosure operating at high temperature that is compatible with both the sealing interfaces and the thermomechanical constraints. This pressure of clamping thus allows the homogeneous transmission of sufficient pressure to maintain, by hydrostatic effect, the pressure exerted on the stack.

[0034] According to one example, the volume of liquid glass frit covers at least the first face and at least one outer wall of the stack so as to generate a counter-pressure. This makes it possible to maintain pressure on the entire stack without additional mechanical means. This also provides a second barrier and protects at least one outer wall of the stack in the event of a localized hydrogen leak.

[0035] According to one example, the dome has a structure configured to adapt to the stack's architecture. The dome thus ensures proper coverage of the stack and provides sufficient internal volume to maintain a frit volume that allows for hydrostatic holding.

[0036] According to one example, the dome has, at least in part, a curved internal surface. This curved internal surface allows it to withstand the internal pressure when the covering gas is pressurized and thus resists a pressure sufficient to maintain the stack in compression.

[0037] According to one example, the dome and the support are metallic parts. Thus, the assembly of elements makes it possible to withstand the high temperatures and pressures used in the context of the invention.

[0038] According to one example, the dome has an opening on its upper part, and a closing plug designed to cooperate in a complementary manner with the opening. The opening typically has a dimension between 1 and 5 cm to allow the insertion of the glass frit. The opening is thus large enough to allow easy insertion of the glass frit but small enough to facilitate the fitting of a plug or connector.

[0039] According to one example, the reactor includes a clamping device, the clamping device comprising a support ring positioned on the first face of the stack and mechanical links, the mechanical links being configured to connect and secure the support ring to the support plate. The clamping device thus makes it possible to maintain the stack in contact with the support plate in a cold state, that is to say, before the reactor is started up. However, the mechanical support does not provide optimal retention, and it is necessary to apply additional support as described in the invention by hydrostatic effect to maintain the stack when the reactor is started up.

[0040] According to one example, the clamping device includes an insulating ring, the insulating ring being positioned between the support ring and the first face of the stack. The insulating ring thus prevents electrical connections between the top of the stack and the support plate, which is a manifold plate, via mechanical links. This prevents reactor malfunction.

[0041] According to one example, the dome includes a support flange configured to fix the dome to the support, the reactor further comprising an insulating spacer positioned between the support flange and the support plate. Since the tempering glass of the stack is not perfectly insulating, this spacer helps to limit parasitic current leakage caused by polarization of the dome.

[0042] According to one example, the dome, the insulating spacer, and the support plate are configured to be fixed together in contact by a mechanical device comprising at least one through-bolt. This mechanical device thus presses the dome against the support to ensure the compression of seals located between each of the interfaces. The mechanical device then ensures the sealing of the internal volume containing the liquid glass and the stack, thereby ensuring proper compression of the stack during pressure buildup.

[0043] According to one example, the mechanical device includes at least one insulating sleeve, the at least one insulating sleeve being configured to insulate the at least one through-bolt. The at least one insulating sleeve thus makes it possible to limit current losses.

[0044] In one example, the operating temperature is above 650 °C. The reactor components can therefore withstand the stack's operating temperatures. In addition, this ensures that a glass bath is properly created around the stack to guarantee homogeneous pressure when the reactor is started up.

[0045] According to one example, the reactor comprises heating blocks, the heating blocks being positioned in contact with an external surface of the dome. The heating blocks thus make it possible to form a glass bath surrounding the stack as closely as possible, with heating devices also located very close to these external walls. The glass bath is thus created rapidly and ensures a homogeneous bath allowing the application of a uniform hydrostatic force.

[0046] According to one example, the reactor comprises a stack, the stack comprising: • an upper plate having a first upper face, the first upper face being configured to be the first face of the stack, • a superposition of at least one electrochemical cell and at least one bipolar plate, positioned along a stacking direction E, • a lower plate having a second lower face, the second lower face being configured to be the second face of the stack.

[0047] According to one example, the support is made of the same material as the upper and lower plates. Thus, making these elements from the same material limits the thermomechanical stresses due to thermal expansion on the seals mounted at the interfaces.

[0048] For example, the upper and lower plates can be made of different materials and have a similar coefficient of thermal expansion. This helps to limit the thermomechanical stresses due to thermal expansion on the seals mounted at the interfaces.

[0049] It is specified that, within the scope of the present invention, the terms "on," "overcomes," "covers," "underlying," "opposite," and their equivalents do not necessarily mean "in contact with." Thus, for example, the depositing, transfer, gluing, assembly, or application of a first element onto a second element does not necessarily mean that the two elements are directly in contact with each other, but means that the first element at least partially covers the second element, either by being directly in contact with it or by being separated from it by at least one other element. These elements may, for example, be layers.

[0050] A layer may also be composed of several sub-layers of the same material or of different materials.

[0051] A frame of reference, preferably orthonormal, comprising the axes X, Y, Z is represented in figures IA to 6B.

[0052] The terms "approximately", "about", "in the order of" mean "to within 10%, preferably to within 5%".

[0053] In the detailed description that follows, terms such as "horizontal", "vertical", "longitudinal", "transverse", "top", "bottom", "upper", and "lower" may be used. These terms should be interpreted in a relative manner with respect to the normal position of the entire electrochemical reactor and its normal direction of position on a plane.

[0054] The present invention relates to an electrochemical reactor 1. The chemical reactor 1 will now be described with reference to Figures IA to 6B.

[0055] The electrochemical reactor 1 is configured to receive a stack 10. The stack 10 has a first face 10a and a second face 10b. The second face 10b is opposite the first face 10a. The first face 10a and the second face 10b may advantageously extend in a plane (XY). The stack 10 also has at least one external wall. This at least one external wall of the stack 10 advantageously connects the first face 10a to the second face 10b. The stack 10 is configured to operate at a temperature referred to as the Top operating temperature. The stack 10 can thus be placed in a heating chamber, also known as the electrochemical reactor 1.

[0056] The electrochemical reactor 1 includes a support 20. An example of the support 20 is shown in [Fig. 1A] and [Fig. 1B]. The support 20 is configured to allow the passage of the feed gases 21 from the stack 10. The passage of the feed gases 21 can be provided by means of pipes. Advantageously, the support 20 can then have four pipes, two pipes being configured to allow the feed gases to enter the stack 10 and two being configured to allow the feed gases to exit the stack 10.

[0057] The support 20 includes a support plate 22. Advantageously, the stack 10 is positioned so that its second face 10 is in contact with the support plate 22. The support 20 and more specifically the support plate 22 can act as a base for the stack 10. The support plate 22 can also serve as a manifold plate.

[0058] The electrochemical reactor 1 further includes a closing dome 30. The closing dome will now be described with reference to [Fig.2A] and [Fig.2B].

[0059] The closing dome 30 has an internal volume Vint. The closing dome 30, and therefore the internal volume Vint, is intended to receive the stack 10. The closing dome 30 is also intended to be hermetically fixed to the support 20. Preferably, at least a portion of the closing dome 30 is positioned in contact with the support plate 22.

[0060] The electrochemical reactor 1 also includes glass frit 40. The glass frit 40 has a volume Vf. The volume Vf of glass frit 40 is positioned within the internal volume Vint of the closing dome 30. The glass frit 40 is configured to undergo a phase transition when the electrochemical reactor 1 reaches the operating temperature Top. The phase transition allows the glass frit 40 to change from a solid form (illustrated, for example, in [Fig. 5B]) to a liquid form (illustrated, for example, in [Fig. 5D]). The liquid glass frit 40 then has a volume Vb; the volume Vi of the liquid frit is then less than the internal volume Vint of the closing dome 30. Furthermore, the liquid glass frit 40 covers the stack 10. The liquid glass frit 40 covers the stack 10 so as to cover the first face 10a of the stack 10. Preferably, the liquid glass frit 40 completely covers the stack 10.The liquid glass frit 40 also has a top face called the free surface 4L.

[0061] The internal volume Vint of the closing dome 30 further comprises a gas called a cover gas 42. The cover gas 42 is positioned above the free surface 4L. More precisely, the cover gas 42 is in contact with the free surface 41 of the liquid frit volume Vi. The cover gas 42 is then configured to be pressurized. Pressurization can be achieved by a pressurization module. under pressure. The pressurization module can be, for example, an injection system linked to a compressor positioned outside the electrochemical reactor 1.

[0062] The blanket gas 42 is pressurized to a clamping pressure Ps. The clamping pressure Ps is configured to maintain the stack 10 on the support plate 22 in compression under a mechanical force proportional to the clamping pressure Ps. Indeed, pressurizing the blanket gas 42 allows the application of a compressive force without using any mechanical devices on the stack 10, transmitted by the liquid glass frit 40.

[0063] The balance of forces in the mechanical assembly, excluding gravity, is as follows: a force applied internally by a pressure of the feed gases 21 of the stack 10 which is equal to an average pressure of the feed gases 21 multiplied by an internal surface of the stack 10 on which it is applied, the force applied by the cover gas 42 on the stack 10 which is equal to the pressure Ps of the cover gas 42 maintained in the closing dome 30 multiplied by an area of ​​the first face 10a of the stack 10.

[0064] With a clamping pressure Ps of cover gas 42 greater than the pressure of the feed gases 21 coupled with a surface of the first face 10a of the stack 10 greater than an internal surface of the stack 10, a compressive force is generated on the first face 10 of the stack 10 transmitted by the liquid glass frit 40.

[0065] The clamping pressure Ps to be applied depends on the dimensions of the stack 10 and the pressure of the supply gases 21. For example, the clamping pressure Ps is between 500 hPa (hectopascals) and 200 kPa (kilopascals). For instance, with a first face 10a of the stack 10 having a diameter of 112.5 mm (millimeters), the pressure required to generate the compression force is on the order of 500 hPa. These low Ps values ​​make it possible to consider the construction of a pressurized enclosure operating at high temperatures that is compatible with both the sealing interfaces and the thermomechanical constraints. The thermomechanical constraints are limited for high-temperature use.

[0066] The liquid glass frit 40 thus allows for a uniform transmission of the compressive force over the entire stack 10. The liquid glass frit 40 also prevents gas leaks from the stack 10. Indeed, according to one example, the volume Vi of liquid glass frit 40 covers at least the first face 10a and at least one external wall of the stack 10 so as to generate a back pressure. This provides a second barrier and protects at least one external wall of the stack 10 in the event of a localized hydrogen leak. Furthermore, compressing the glass frit 40 ensures better sealing. by generating a back pressure preventing the bubbling of leaking gases in the glassy matrix.

[0067] As explained previously, the reactor 1 is configured to receive a stack 10. The stack 10 is positioned on the support plate 22 of the support 20. A possible stack 10 is shown in figures 3A and 3B and will now be described.

[0068] According to one example, the stack 10 comprises an upper plate 11. The upper plate 11 may have a first face 111. The first face 111 of the upper plate 11 can be considered as the first face 10a of the stack 10. The stack 10 may also comprise a lower plate 13. The lower plate 13 has a second face 132. The second face 132 can be considered as the second face 10b of the stack 10. Between the upper plate 11 and the lower plate 13, the stack 10 may comprise a superposition 12 of at least one electrochemical cell and at least one bipolar plate. Advantageously, the lower plate 13, the superposition 12 and the upper plate 11 are superimposed on one another in a stacking direction E. As an example, the electrochemical reactor 1 comprises a stacking 10 as described above.

[0069] The upper plate 11 and the lower plate 13 can advantageously be made of the same material. Furthermore, the support 20, and more specifically the bearing plate 22, can be made of the same material as the upper plate 11 and the lower plate 13. At least a portion of the bearing plate 22 and the upper and lower plates 11 and 13 will be subjected to high temperatures during the operation of the electrochemical reactor 1. Thus, making these elements from the same material helps to limit the thermomechanical stresses due to thermal expansion on the seals mounted at the interfaces.

[0070] The upper plate 11 and the lower plate 13 can advantageously be made of different materials having a similar coefficient of thermal expansion. A similar coefficient of thermal expansion is defined as a coefficient whose difference between them does not exceed ±106 °C. This helps to limit the thermomechanical stresses due to thermal expansion on the seals mounted at the interfaces.

[0071] According to one example, the electrochemical reactor 1 includes a clamping device 50. The clamping device 50 is configured to maintain the compression of the cold stack 10. Thus, the clamping device 50 can be positioned from so as to apply pressure in the direction of the support 20 on the first face 10a of the stack 10.

[0072] The clamping device 50 may then include a support ring 51. The support ring 51 is then configured to be positioned on the first face 10a of the stack 10. Similarly, the support ring 51 is positioned on the first upper face 111 of the upper plate 11 of the stack 10. Advantageously, the support ring 51 does not completely cover the surface of the first face 10a of the stack 10. The support ring 51 may then be positioned on a periphery of the first face 10a of the stack 10.

[0073] The clamping device 50 may also include mechanical links 52. The mechanical links 52 are configured to connect the support ring 51 to the support plate 22. More specifically, the mechanical links 52 are configured to secure the support ring 51 to the support plate 22. The mechanical links 52 thus ensure contact between the second face 10b of the stack 10 and the support plate 22 when the reactor 1 is cold. The mechanical links 52 may, for example, be compression tie rods. The mechanical links 52 are then positioned on a periphery of the stack 10. The clamping device 50 has at least two mechanical links 52. The at least two mechanical links 52 are positioned so as to have at least one symmetry on the stack axis E. Thus, the applied compression force is homogeneous over the entire stack 10.

[0074] Advantageously, the clamping device 50 also includes an insulating ring 53. The insulating ring 53 is then positioned between the support ring 51 and the first face 10a of the stack 10. The insulating ring 53 thus avoids electrical connections between the top of the stack 10 and the support plate 22, which is a manifold plate, via the mechanical links 52. Like the support ring 51, the insulating ring 53 is positioned on a periphery of the first face 10a of the stack 10. Preferably, the insulating ring 53 and the support ring 51 have the same dimensions.

[0075] The stack 10 can be cylindrical or parallelepiped in shape. Figures 3A to 5D illustrate, without limitation, a cylindrical stack 10. Figures 6A and 6B illustrate, without limitation, a parallelepiped stack 10. Therefore, to ensure proper operation, the closing dome 30 must be adapted to the shape of the stack 10. The closing dome 30 can thus have a structure configured to adapt to the architecture of the stack 10.

[0076] Once the stack 10 is assembled and / or positioned on the support 20, the dome 30 can be put in place on top of the stack 10.

[0077] The dome 30 may advantageously include a support flange 31. The support flange 31 is configured to fix the dome 30 to the support 22. More specifically, the support flange 31 includes a plurality of holes 35 (illustrated in [Fig. 2A]). The holes 35 are then configured to align with openings 23 (illustrated in [Fig. 1A]) present on the support plate 22 of the support 20. The support flange 31 is thus positioned opposite the support plate 22.

[0078] The reactor 1 may further include an insulating spacer 33 positioned between the support flange 31 and the support plate 22 of the support 20. Advantageously, the insulating spacer 33 extends only between the support flange 31 and the support plate 22. Since the tempering glass of the stack 10 is not perfectly insulating, this spacer 33 helps to limit parasitic current leakage created by a polarization of the dome 30.

[0079] Thus, the dome 30, the insulating spacer 33, and the support plate 22 can be configured to be fastened together in contact by a mechanical device 34. The mechanical device 34 thus allows the dome 30 to be pressed against the support 20 in order to compress the sealing gaskets 343 located between each of the interfaces. The mechanical device 34 may then include at least one through-bolt clamping screw 341. The at least one through-bolt clamping screw 341 is configured to pass through at least one hole 35 and to be inserted into an opening 23 in the support 20. The at least one opening 23 may then have a threaded section to allow the through-bolt clamping screw 341 to be tightened. The mechanical device 34 includes as many through-bolt clamping screws 341 as there are holes 35 in the support flange 31.

[0080] Preferably, the mechanical device 34 also includes at least one insulating sleeve 342. This at least one insulating sleeve 342 is then configured to insulate at least one through-bolt clamping screw 341. This at least one insulating sleeve 342 thus limits current losses. Therefore, the mechanical device 34 includes as many insulating sleeves 342 as it includes through-bolt clamping screws 341.

[0081] Additionally, the closing dome 30 may have at least one convex internal surface on its upper portion. This convex internal surface helps to withstand the internal pressure when the covering gas 42 is pressurized. A convex internal surface is defined as a convex internal surface.

[0082] Similarly, the dome 30 may have an opening 32 on its upper part. The opening 32 is configured to allow the insertion of the glass frit 40 into the reactor 1 once the dome 30 is fixed to the support 20. To this end, the opening 32 typically has a dimension between 1 and 5 cm. The opening 32 is thus large enough to allow easy insertion of the 40 glass frit but small enough to facilitate the fitting of a cap or fitting.

[0083] According to one example, the dome 30 may have a closing plug 43. The plug 43 is shown, for example, in Figures 5C and 5D. The plug 43 is designed to cooperate in a complementary manner with the opening 32. The plug 43 thus allows the dome 30 to be closed and the internal volume Vint to be made airtight. The plug 43 is thus configured to ensure a seal against pressurized gases. The plug 43 is advantageously fixed to the opening 32 by welding or by a gasket, for example, a metal gasket. The plug 43 is thus hermetically fixed to the dome 30. The closing plug 43 may advantageously have a pipe. The pipe can then be configured to allow the creation of a branch connection for inserting the covering gas 42. The pipe can then be included in the pressurization module. The covering gas 42 inserted through the pipe can then be pressurized.

[0084] According to one example, the assembly of elements is configured to withstand high temperatures and pressures as described above. Advantageously, the dome 30 is thus a metallic part. More precisely, the dome 30 is made of an alloy suitable for high-temperature use. Similarly, the support 20 is also a metallic part. The support 20 is therefore also made of an alloy suitable for high-temperature use. High temperature is understood, for example, to mean temperatures between 600 °C and 900 °C.

[0085] In one example, the operating temperature Top is above 650 °C. Preferably, the operating temperature Top is below 900 °C. The elements of reactor 1 can thus withstand the operating temperatures of the stack 10. Furthermore, the formulation of the glass frit 40 is chosen so that the melting point temperature of the glass is below the operating temperature Top of the stack 10. The formulation of glass 40 also ensures a vitreous, viscous, weakly crystallized, or uncrystallized glass bath. During the initial melting of the frit 40, the volume of glass Vidiminue (between 30 and 50%). In order to ensure that, once melted, the glass matrix completely covers the stack, the volume Vint of the dome 30 must be sized to be able to be filled with a sufficient volume Vf of glass frit 40.

[0086] Thus, during the operation of reactor 1, it is ensured that the glass 40 is in liquid form and therefore, together with the pressurized blanket gas, exerts a compressive force on the stack 10. Once the stack 10 is completely immersed by the liquid glass, the pressurization of the blanket gas 42 then allows to compress it under a mechanical force proportional to the clamping pressure Ps. By hydrostatic effect, the pressure Pexed on the free face 41 of the liquid glass is transmitted fully and perfectly homogeneously to the upper plate 11 of the stack 10, without requiring mechanical components such as force distributors or support rods / platforms. The compressive force transmitted to the stack 10 is easily adjustable by varying the clamping pressure Ps. The proposed device thus constitutes an active system allowing continuous adjustment of the compressive force according to the internal pressure of the stack 10.

[0087] According to an example illustrated in Figures 6A and 6B, the reactor 1 includes heating blocks 60. The heating blocks 60 can then be positioned in contact with an external surface of the dome 30. The heating blocks 60 thus make it possible to form a glass bath surrounding the stack 10 as closely as possible with heating devices also located very close to these external walls.

[0088] The process of pressurizing the electrochemical reactor 1 can then include the following steps.

[0089] The method may include positioning the stack 10 on the support 20.

[0090] The method may then include positioning the dome 30 on the support 20. The dome 30 is then positioned so as to surround the stack 10. The dome 30 is then fixed to the support 20. It can be fixed by positioning the mechanical clamping device 34.

[0091] The process then includes filling the dome 30 with a volume Vf of glass frit 40. The filling is then carried out by inserting the glass frit 40 through the opening 32 located on an upper part of the dome.

[0092] The method then includes fixing a plug 43 in the opening 32. This fixing can be achieved by welding or via a gasket. This fixing is configured to make the internal volume Vint of the dome 30 airtight.

[0093] The process then includes increasing the temperature in the reactor 1 so as to reach the operating temperature Top. This step leads to the melting of the frit 40 which becomes a bath of liquid vitreous glass having a volume Vi at the operating temperature.

[0094] Finally, the method includes pressurizing the reactor 1 to a clamping pressure Ps. This pressurization is carried out by a pressurization module. The module may include a compressor connected to a pipe located in the plug 43. The pressurization module can thus directly inject the blanket gas 42 into the internal volume of the pressurized dome 30.

[0095] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

[0096] NUMERICAL REFERENCES 1: Electrochemical reactor 10: stacking 10a: first face 10b: second side 11: top plate 111: first upper face 112: second upper face 12: Alternating electrochemical cells and bipolar plates 13: lower plate 131: first lower face 132: second lower face 20: support 21: Feed gas 22: Support plate 23: Openings 30: Closing dome 31: support flange 32: Opening 33: Insulating spacer 34: Mechanical clamping device 341: clamping screw 342: Insulating sleeves 343: joints 35: holes 40: glass frit 41: free face of the liquid glass frit volume 42: blanket gas 43: closing cap 50: clamping device 51: support ring 52: mechanical connection (compression rods) 53: insulating ring 60: heating blocks Top: stack operating temperature E: stacking direction Vint ■ internal volume of dome Vf: volume of glass frit Vi: volume of liquid glass frit P.S.: clamping pressure

Claims

1. Demands An electrochemical reactor (1), configured to receive a stack (10) having a first face (10a) and a second face (10b) opposite the first face (10a) and at least one external wall connecting the first face (10a) to the second face (10b) and configured to operate at an operating temperature (T^), the reactor (1) comprising: • a support (20) configured to ensure the passage of the feed gases (21) of the stack (10), the support comprising a support plate (22), the stack (10) being positioned so that its second face (10b) is in contact with the support plate (22), characterized in that the reactor (1) further comprises: • a closing dome (30), having an internal volume (Vint), intended to receive the stack (10) and to be hermetically fixed onto the support, • of the glass frit (40) having a glass frit volume (Vf) and positioned in the internal volume (Vint), and configured to carry out a phase transition at the operating temperature (Top) of the stack (10) so as to form liquid glass frit (40) having a liquid glass frit volume (Vi) and further configured to cover the stack (10), the liquid glass frit volume (VJ) being less than the internal volume (Vint) and having a top face called free surface (41), the internal volume (Vint) further comprising a gas called cover gas (42), the cover gas (42) being positioned above and in contact with the free surface (41) of the liquid frit volume (Vi), the cover gas (42) being configured to be pressurized to a clamping pressure (Ps) by a pressurizing module, the clamping pressure (Ps) being configured so as to maintain in compression the stack (10) on the support plate (22) under a mechanical force proportional to the clamping pressure (Ps).

2. Electrochemical reactor (1) according to the preceding claim in which the clamping pressure (Ps) is between 500 hPa and 200 kPa.

3. Electrochemical reactor (1) according to any one of the preceding claims wherein the volume of liquid glass frit (Vi) covers at least the first face (10a) and at least one external wall of the stack (10) so as to generate a back pressure.

4. Electrochemical reactor (1) according to any one of the preceding claims wherein the dome (30) has a structure configured to fit the architecture of the stack (10).

5. Electrochemical reactor (1) according to any one of the preceding claims in which the dome (30) has, at least on a portion, a domed internal surface.

6. Electrochemical reactor (1) according to any one of the preceding claims wherein the dome (30) and the support (20) are metallic parts.

7. Electrochemical reactor (1) according to any one of the preceding claims wherein the dome (30) has an opening (32) on an upper part of the dome (30), and a closing plug (43) intended to cooperate in a complementary manner with the opening (32), the opening (32) having a dimension typically between 1 and 5 cm so as to permit the insertion of the glass frit (40).

8. Electrochemical reactor (1) according to any one of the preceding claims comprising a clamping device (50), the clamping device (50) comprising a support ring (51) positioned on the first face (10a) of the stack (10) and mechanical links (52), the mechanical links (52) being configured so as to connect and secure the support ring (51) to the support plate (22).

9. Electrochemical reactor (1) according to the preceding claim in which the clamping device (50) comprises an insulating ring (53), the insulating ring (53) being positioned between the support ring (51) and the first face (10a) of the stack (10).

10. Electrochemical reactor (1) according to any one of the preceding claims, wherein the dome (30) comprises a support flange (31) configured to fix the dome (30) to the support (22), the reactor further comprising an insulating spacer (33) positioned between the support flange (31) and the support plate (22) of the support (20).

11. Electrochemical reactor (1) according to the preceding claim in which the dome (30), the insulating spacer (33) and the support plate (22) are configured so as to be fixed together in contact by a mechanical device (34) comprising at least one through clamping screw (341).

12. Electrochemical reactor (1) according to the preceding claim in which the mechanical device (34) comprises at least one insulating sleeve (342), the at least one insulating sleeve (342) being configured to insulate the at least one through clamping screw (341).

13. Electrochemical reactor (1) according to any one of the preceding claims wherein the operating temperature (T^) is greater than 650 °C.

14. Electrochemical reactor (1) according to any one of the preceding claims wherein the reactor (1) comprises heating blocks (60), the heating blocks (60) being positioned in contact with an external surface of the dome (30).

15. Electrochemical reactor (1) according to any one of the preceding claims comprising a stack (10), the stack (10) comprising: • an upper plate (11) having a first upper face (111), the first upper face (111) being configured to be the first face (10a) of the stack (10), • a superposition (12) of at least one electrochemical cell and at least one bipolar plate, positioned along a stacking direction E, • a lower plate (13) having a second lower face, the second lower face (132) being configured to be the second face (10b) of the stack (10).

16. Electrochemical reactor (1) according to the preceding claim in which the support (20) is made of a material identical to the material of the upper plate (11) and the lower plate (13).

17. A method for pressurizing an electrochemical reactor (1) according to any one of the preceding claims in combination with claim 7, wherein the method comprises: • positioning the stack (10) on the support (20), • positioning and fixing the dome (30) on the support (20) so as to surround the stack (10), • filling the dome (30) with glass frit (40) through an opening (32), • fixing a plug (43) in the opening (32) so as to make the internal volume (Vint) of the dome (30) airtight, • increasing the temperature in the reactor so as to reach the operating temperature (T^), • pressurizing the reactor (1) up to a clamping pressure (Ps) by the pressurizing module.

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