System for adjusting a plurality of stacks of SOEC / SOFC type solid oxide cells at high temperature

Abstract

The main object of the invention is a system (100) for adjusting a number of stacks (20) of solid oxide cells of the SOEC / SOFC type, characterized in that it comprises a thermal housing (102) delimiting an internal volume (Vi), frames (104) arranged on both sides of the thermal housing (102), a first cross-member device (108) attached to the frame (104) in a movable manner relative to the frame (104), a number of clamping rods (110) intended to come into contact with the stacks (20) and to be able to clamp the stacks (20), and a number of elastic return members (112) fixed to the clamping rods (110) and to the first cross-member device (108), such that each clamping rod (110) is supported by an elastic return member (112) that can be compressed under the effect of the weight of the clamping rod (110).

Description

Technical Field

[0001] The present invention relates to the general field of high temperature electrolysis (HTE), in particular high temperature steam electrolysis (HTSE), electrolysis of carbon dioxide (CO2), or co - electrolysis of steam and carbon dioxide (CO2) at high temperature.

[0002] More specifically, the present invention relates to the field of high - temperature solid oxide electrolysis devices, which are usually denoted by the acronym SOEC (short for "solid oxide electrolysis cell").

[0003] This also relates to the field of high - temperature solid oxide fuel cells, which are usually referred to by the acronym SOFC.

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

[0005] More specifically, the present invention relates to a system for coordinating a plurality of stacks of SOEC / SOFC - type solid oxide cells operating at high temperature and enabling simultaneous coordination of the stacks.

Background Art

[0006] In the context of a SOEC-type high-temperature solid oxide electrolyzer, this involves converting water vapor (H2O) into hydrogen (H2) or methane (CH4), natural gas, biogas, and other fuels such as dioxygen (O2) through an electric current within the same electrochemical device, and / or converting carbon dioxide (CO2) into carbon monoxide (CO) and dioxygen (O2). In the context of a SOFC-type high-temperature solid oxide fuel cell, the operation is reversed, and hydrogen (H2) and dioxygen (O2) are used to generate an electric current and heat, usually by supplying air and natural gas, i.e., methane (CH4). For the sake of simplicity, in the following description, the operation of a SOEC-type high-temperature solid oxide electrolyzer that performs the electrolysis of water vapor is prioritized. However, this operation is also applicable to the electrolysis of carbon dioxide (CO2) or the high-temperature co-electrolysis of water vapor (HTE) and carbon dioxide (CO2). Furthermore, this operation can be replaced in the case of a SOFC-type high-temperature solid oxide fuel cell.

[0007] To perform the electrolysis of water, it is advantageous to perform this at a high temperature, usually between 600 °C and 1000 °C, because it is more advantageous to electrolyze water vapor rather than liquid water, and because a part of the energy required for the reaction can be provided by heat, which is cheaper than electricity.

[0008] To carry out high-temperature steam electrolysis (HTSE), a SOEC-type high-temperature solid oxide electrolyzer consists of a stack of basic units each containing a solid oxide electrolysis cell, or electrochemical cell, composed of three anode / electrolyte / cathode layers stacked on top of each other, and an interconnect plate made of a metal alloy, also called a bipolar plate or interconnector. Each electrochemical cell is clamped between two interconnect plates. A SOEC-type high-temperature solid oxide electrolyzer is then an alternating stack of electrochemical cells and interconnectors. A SOFC-type high-temperature solid oxide fuel cell consists of a stack of the same type of basic units. This high-temperature technology is reversible, and the same stack can operate in electrolysis mode to produce hydrogen and oxygen from water and electricity, or in fuel cell mode to produce electricity from hydrogen and oxygen.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a multilayer ceramic assembly in which the electrolyte is formed by a central ion-conducting layer that is solid, dense, sealed, and clamped between two porous layers that form the electrodes. Additional layers may be present, but it should be noted that these only serve to improve one or more of the layers already described.

[0010] The interconnect device, which is electrical and fluidic, ensures, from an electrical point of view, the connection of each electrochemical cell of the basic unit in the stack of basic units, the electrical contact between one face of the cell and the cathode and between the other face of the next cell and the anode, and, from a fluidic point of view, the supply of reagents and the discharge of products for each of the cells. The interconnector thus provides the function of supplying and collecting current and delimits the gas circulation chambers for distribution and / or collection.

[0011] More specifically, the main functions of the interconnector are not only to allow the passage of current but also to ensure the circulation of gases (i.e., air and fuel containing injected steam, hydrogen and oxygen extracted for HTE electrolysis, injected hydrogen and extracted steam for SOFCs) near each cell, and to separate the anode and cathode chambers of two adjacent cells, which are the gas circulation chambers on the anode and cathode sides of the cell respectively.

[0012] In particular, in a high-temperature solid oxide electrolyzer of the SOEC type, the cathode chamber contains water vapor and hydrogen, which are the products of the electrochemical reaction, while the anode chamber contains, if present, exhaust gas and oxygen, which is another product of the electrochemical reaction. In a high-temperature solid oxide fuel cell of the SOFC type, the anode chamber contains fuel while the cathode chamber contains an oxidant.

[0013] To perform high-temperature steam electrolysis (HTE), steam (H2O) is injected into the cathode chamber. Under the influence of the current applied to the cell, the dissociation of water molecules in the form of steam is carried out at the interface between the hydrogen electrode (cathode) and the electrolyte, and this dissociation produces dihydrogen gas (H2) and oxygen ions (O 2- ). Dihydrogen (H2) is collected and discharged at the outlet of the hydrogen chamber. Oxygen ions (O 2- ) move through the electrolyte and recombine into dioxygen (O2) at the interface between the electrolyte and the oxygen electrode (anode). Since an exhaust gas such as air circulates at the anode, the oxygen produced in gaseous form can be collected at the anode.

[0014] To ensure the operation of a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode chamber of the fuel cell and hydrogen is injected into the anode chamber. The oxygen in the air will dissociate into O 2- ions. These ions move through the electrolyte from the cathode to the anode to oxidize hydrogen, forming water and generating electricity at the same time. In an SOFC, just like in SOEC electrolysis, steam is found in the dihydrogen (H2) chamber. Only the polarity is reversed.

[0015] By way of example, FIG. 1 shows a schematic diagram illustrating the operating principle of an SOEC-type high-temperature solid oxide electrolyzer. The function of such an electrolyzer is to convert steam into hydrogen and oxygen according to the following electrochemical reaction. 2H2O → 2H2 + O2.

[0016] This reaction is carried out electrochemically in the cell of the electrolyzer. As schematically shown in FIG. 1, each basic electrolysis cell 1 is formed by a cathode 2 and an anode 4 arranged on both sides of a solid electrolyte 3. The two electrodes (cathode and anode) 2 and 4 are electron and / or ion conductors made of a porous material, and the electrolyte 3 is an airtight, electron insulator and ion conductor. The electrolyte 3 can be an anion conductor, more precisely an anion conductor of O 2- ions, and the electrolyzer is then called an anion electrolyzer in contrast to a proton electrolyte (H + ).

[0017] The electrochemical reaction occurs at the interface between each of the electron conductors and the ion conductor.

[0018] At the cathode 2, the half-reaction is as follows. 2H2O + 4e - →2H2+ 2O 2- .

[0019] At the anode 4, the half-reaction is as follows. 2O 2- →O2+ 4e - .

[0020] The electrolyte 3 intervening between the two electrodes 2 and 4 is the place where O 2- ions move under the influence of the electric field created by the potential difference imposed between the anode 4 and the cathode 2.

[0021] As shown in the brackets in FIG. 1, the water vapor at the cathode inlet can be accompanied by hydrogen H2, and the hydrogen generated and recovered at the outlet can be accompanied by water vapor. Similarly, as shown by the dotted line, it is also possible to inject an exhaust gas such as air at the anode-side inlet and discharge the generated oxygen. The injection of the exhaust gas has an additional function of acting as a thermostat.

[0022] The basic electrolysis device, or electrolytic reactor, consists of the basic cell as described above, which includes a cathode 2, an electrolyte 3, and an anode 4, and two interconnects that provide the functions of electrical and fluid distribution.

[0023] To increase the flow rates of the generated hydrogen and oxygen, it is known to stack several basic electrolysis cells separated by interconnects on top of each other. This assembly is arranged between two end interconnect plates that support the power supply and gas supply to the electrolysis device (electrolytic reactor).

[0024] The SOEC type high-temperature solid oxide electrolyzer thus includes at least one, usually a plurality of, electrolysis cells stacked on top of each other, and each basic cell is formed of an electrolyte, a cathode, and an anode, with the electrolyte intervening between the anode and the cathode.

[0025] As shown previously, the fluid and electrical interconnection devices that are in electrical contact with one or more electrodes generally provide the function of supplying and collecting electric current and delimit one or more gas circulation chambers.

[0026] Therefore, the function of the compartment called the cathode chamber is the distribution of electric current and water vapor, as well as the recovery of hydrogen at the contacting cathode.

[0027] The compartment called the anode chamber has the function of distributing electric current and, possibly using the exhaust gas, recovering the oxygen generated at the contacting anode.

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

[0029] The interconnector 5 is a metal alloy component that ensures the separation between the cathode chamber 50 and the anode chamber 51, which are respectively defined by the volumes between the interconnector 5 and the adjacent cathode 2.1, and between the interconnector 5 and the adjacent anode 4.2. This also ensures the gas distribution to the cells. The injection of steam into each basic unit is carried out in the cathode chamber 50. The collection of hydrogen and residual steam generated at the cathodes 2.1, 2.2 is carried out in the cathode chamber 50 downstream of the cells C1, C2 after the dissociation of steam by the cells C1, C2. The collection of oxygen generated at the anode 4.2 is carried out in the anode chamber 51 downstream of the cells C1, C2 after the dissociation of steam by the cells C1, C2. The interconnector 5 ensures the passage of current between the cells C1 and C2 by direct contact between the adjacent electrodes, namely the anode 4.2 and the cathode 2.1.

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

[0031] Therefore, for the proper operation of such a stack of solid oxide cells of the SOEC / SOFC type operating at high temperatures, it is mainly required to meet the points described below.

[0032] First, it is necessary to have electrical insulation between two consecutive interconnectors; otherwise, the electrochemical cell will short-circuit. However, it is also necessary to have good electrical contact and sufficient contact area between the cell and the interconnector. As low an ohmic resistance as possible is required between the cell and the interconnector.

[0033] Also, it is necessary to have a seal between the anode chamber and the cathode chamber; otherwise, the generated gases will recombine, leading to a decrease in efficiency and, in particular, the appearance of hot spots that damage the stack.

[0034] Finally, it is essential to have good gas distribution both at the inlet and during product recovery, otherwise, a decrease in yield, pressure and temperature non-uniformities within different basic units, or even significant degradation of the electrochemical cell will occur.

[0035] The inlet and outlet gases in a high-temperature electrolysis stack (SOEC) or fuel cell (SOFC) operating at high temperatures can be managed by a device as described with reference to Figure 3. The device 10 thus includes a low-temperature part PF and a high-temperature part PC, and the high-temperature part PC includes the base of the oven 11, a loop tube 12 that manages the gas inlet and outlet, and a high-temperature electrolysis stack 20 (SOEC) or fuel cell (SOFC).

[0036] Also, Figure 4 shows an example of an assembly 80 including such a stack 20 and its clamping system 60. Such an assembly 80 can be as described in Patent Document 1.

[0037] Thus, the stack 20 includes a plurality of electrochemical cells 41 each formed of a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects 42 respectively disposed between two adjacent electrochemical cells 41. In addition, it includes an upper end plate 43 and a lower end plate 44, also respectively referred to as an upper stack end plate 43 and a lower stack end plate 44, between which a plurality of electrochemical cells 41 and a plurality of intermediate interconnects 42 are clamped, or a stack is disposed between the upper end plate 43 and the lower end plate 44.

[0038] The clamping system 60 includes an upper clamping plate 45 and a lower clamping plate 46, and a stack 20 is clamped between the upper clamping plate 45 and the lower clamping plate 46. Each clamping plate 45, 46 includes four clamping orifices 54 through which a clamping stem 55, or a tie rod, extends. Clamping means 56, 57, 58 are provided at the ends of the above-mentioned stem.

[0039] Generally, heretofore, the stack 20 has had a limited number of electrochemical cells 41.

[0040] Prior to its operation, it is necessary to subject the stack 20 to at least one heat treatment step called a reduction heat treatment step in order to bring the electrochemical cell 41 to its reduced form and not oxidize it as it was initially. This reduction step can be a thermomechanical cycle under a reducing gas for the hydrogen electrode and air or a neutral gas for the oxygen electrode. Such a heat treatment step is described, for example, in Patent Document 2.

[0041] Also, stacks 20 implemented heretofore generally use joints at each of their stages, and these joints must ensure the sealing between two adjacent separate gas circulation chambers, namely the anode chamber and the cathode chamber. Such joints are described in Patent Document 3. These joints have the particularity that they require pressing, fixing, and heat adjustment with changes in microstructure.

[0042] In addition, contact elements such as the layers or nickel grids described in Patent Document 4 are also pressed in during heat adjustment and during the operation of the stack 20, thereby ensuring its proper implementation. Elements that serve as contact elements in the hydrogen chamber are also pressed in.

[0043] In other words, during the heat adjustment step, the stack 20 is pushed in by several centimeters. Heretofore, since the number of stacked cells has been relatively small, the pushing in has proceeded correctly.

[0044] However, the applicant has considered manufacturing stacks with a larger number of electrochemical cells. In this case, the movements expected when clamping the stack can lead to mechanical blocking problems of the bracing type on the guide stem. These blockages prevent good transmission of the clamping force and thus good thermal regulation, and consequently the normal operation of the stack.

[0045] A solution to these drawbacks is to provide a stack concept in which several sub-stacks are assembled by means of reinforcement plates so as to cope with large push-ins. However, at this time, since each sub-stack needs to be adjusted separately, a large number of stacks and sub-stacks have to be manufactured.

[0046] However, since heating requires energy, adjusting such stacks is a long and costly step. In addition, with current devices, it is possible to adjust a single stack or sub-stack at a time.

[0047] As a result, there is still a need to improve the principle of adjusting high-temperature electrolysis stacks (SOEC) or fuel cells (SOFC), especially in order to adjust several stacks simultaneously.

Prior Art Documents

Patent Documents

[0048]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0049] The present invention aims to at least partially address the above-mentioned needs and the drawbacks of the prior art embodiments.

[0050] In particular, it aims to achieve a plurality of adjustment designs for a high-temperature electrolysis stack (SOEC) or a fuel cell stack (SOFC), while maintaining a controlled clamp despite the large push stroke of the stack.

Means for Solving the Problems

[0051] The present invention thus, according to one of its aspects, has a system for adjusting a plurality of stacks of SOEC / SOFC type solid oxide cells operating at high temperature, each stack including a plurality of electrochemical cells respectively formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects respectively disposed between two adjacent electrochemical cells, and the system includes a thermal housing that delimits an internal volume, a plurality of stacks disposed in the internal volume, frames disposed on both sides of the thermal housing, a first cross-member device that is superimposed on the thermal housing and movably attached to the frame with respect to the frame, a plurality of clamp rods, each stack being associated with one or more clamp rods, the clamp rods being attached through the first cross-member device and intended to be able to contact the stack and clamp the stack, a plurality of elastic return members, each stack being associated with one or more elastic return members, each elastic return member being attached around the clamp rod, fixed to the clamp rod by a first end by a fixing element, and fixed to the first cross-member device by a second end by a guide and holding element, such that the clamp rod is supported by an elastic return member that can be compressed under the influence of the weight of the clamp rod. It is characterized by including.

[0052] The adjustment system according to the present invention can further include one or more of the following features, which are adopted individually or in any possible technical combination.

[0053] The number of stacks can be included between 2 and 100. Preferably, the number of stacks is equal to 4, and in particular, it can be arranged in two rows of two each so as to enable a good balance of the first cross member device that can be in a cross shape.

[0054] In addition, the adjustment system according to the present invention can include a base that is arranged inside the thermal housing and on which a plurality of stacks are arranged.

[0055] Each stack can be associated with a number of elastic return members included between 1 and 10. Each stack is particularly associated with a single unique elastic return member and a single unique clamping rod. It should be noted that it is also possible for each stack to have a plurality of clamping rods. The advantage would be to reduce the forces provided by each rod and each elastic return member. Alignment of the clamps is then facilitated.

[0056] Preferably, the stacks can be arranged on the same plane. In other words, the stacks can be arranged adjacent to each other, and advantageously do not overlap each other.

[0057] Furthermore, the rigidity of each elastic return member can be included between 0.1 N / mm and 1000 N / mm, particularly between 1 N / mm and 20 N / mm.

[0058] The length of each elastic return member can be included between 0.1 m and 10 m, particularly between 1 m and 2 m.

[0059] The number of electrochemical cells can preferably be 25 or more. However, the present invention is also applicable to a number of electrochemical cells less than 25.

[0060] Furthermore, the adjustment system according to the invention includes at least one support for the stack, in particular one support per stack, the support being fixed to the frame and in particular being able to be formed through a base on which a plurality of stacks are arranged.

[0061] Furthermore, according to another one of its aspects, the invention also relates to a method for clamping a plurality of stacks of SOEC / SOFC type solid oxide cells operating at high temperature by means of an adjustment system as defined above, this method being characterized in that it comprises a step consisting of moving a first cross-member device in the direction of the plurality of stacks relative to the frame.

[0062] This method can advantageously be carried out under an inert gas.

[0063] The invention can be better understood by reading the following detailed description, its non-limiting examples of implementation, and by considering the schematic and partial views of the accompanying drawings.

Brief Description of the Drawings

[0064]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0065] In all of these figures, the same reference numerals can indicate the same or similar elements.

[0066] In addition, for the sake of easier reading of the figures, the different parts shown in the figures are not necessarily on a uniform scale.

[0067] FIGS. 1 to 4 have already been described above in the section regarding the prior art and the technical context of the present invention. In FIGS. 1 and 2, symbols and arrows for the supply of water vapor H2O, the distribution and recovery of hydrogen H2, oxygen O2, air and electric current are shown for the purpose of clarity and accuracy, making it clear that the operation of the illustrated apparatus is being described.

[0068] Furthermore, it should be noted that all components (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramic. The operating temperature of a high-temperature SOEC / SOFC type stack is also usually included between 600°C and 1000°C.

[0069] In addition, the possible terms "upper" and "lower" should be understood here in accordance with the normal direction of the orientation of the SOEC / SOFC type stack when in its use configuration.

[0070] An example of the adjustment system 100 according to the present invention for some SOEC / SOFC type stacks 20 will be described next with reference to FIGS. 5 to 7 regarding the same embodiment shown in different figures. A variant will be described with reference to FIG. 8.

[0071] Consider here the adjustment of the three stacks 20. However, the number of stacks 20 can be much larger, especially included between 2 and 100. In particular, at this time, advantageously, four stacks 20 can be arranged in two rows of two each so as to improve the balance of the first cross member device 108 which is in a cross shape. Advantageously, the stacks 20 are arranged adjacent to each other in the same plane and thus do not overlap each other.

[0072] In FIG. 5, an adjustment system 100 according to the present invention is shown, but no clamping or contact occurs with the three stacks 20.

[0073] As described above in the part regarding the prior art and the technical context of the present invention, each stack 20 includes a plurality of electrochemical cells 41 respectively formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects 42 respectively arranged between two adjacent electrochemical cells 41.

[0074] The three stacks 20 are arranged in the internal volume Vi of the thermal housing 102 of the adjustment system 100. In addition, frames 104 are arranged on both sides of the thermal housing 102, and these frames 104 can receive mechanical forces.

[0075] A first cross member device 108 that is movable relative to the frame 104, for example, slidable, is attached to this frame 104. This first cross member device 108 is placed on top of the thermal housing 102 and is arranged above the thermal housing 102 in FIG. 5.

[0076] Also, three clamping rods 110 are attached to each stack 20 one by one through the first cross member device 108, for example, by orifices formed in the first cross member device 108. These three clamping rods 110 enable the clamping of the three stacks 20.

[0077] The hot housing 102 includes an opening larger than the clamping rod 110. A small amount of heat-insulating wool is placed in this opening, maintaining flexibility so as to limit heat loss without impeding movement.

[0078] In addition, advantageously, three springs 112 are used, one spring 112 for each stack 20. Each spring 112 is mounted around its corresponding clamping rod 110. The spring 112 is then fixed to the clamping rod 110 by the fixing element 116 at its first end 112a, and fixed to the first cross-member device 108 by the guide and holding element 118 at its second end 112b. In other words, in this raised position of the first cross-member device 108 as seen in FIG. 5, the clamping rod 110 rests on the spring 112. In fact, each spring 112 is fixed to the corresponding clamping rod 110 by the fixing element 116, and the guide and holding element 118 enables the guiding of the clamping rod 110 and the holding of the spring 112 with respect to the first cross-member device 108. Thus, the clamping rod 110 is supported by the spring 112, and the spring 112 is compressed due to the weight of the clamping rod 110.

[0079] It should be noted that the stiffness of each spring 112 is included between 0.1 N / mm and 1000 N / mm, preferably between 1 N / mm and 20 N / mm. In addition, the length of each spring 112 is included between 0.1 m and 10 m, preferably between 1 m and 2 m.

[0080] Advantageously, the selection of the stiffness / length combination of each spring 112 can be made such that only a few percent of the crush or slack of a few tens of millimeters affects the nominal clamp. With a large spring 112 of low stiffness and a large length, for example 1.5 m, it is possible to easily apply a force of several kN with good accuracy even if the size of the object to which the force is applied changes significantly.

[0081] For example, 25 cells and 200 cm 2The stack 20 or sub-stack must be clamped to 4000 N. The push-in stroke during adjustment is about 35 mm. Therefore, with a spring 112 of 1.5 m and a stiffness of 6 N / mm, it is sufficient to push in the spring 112 by 800 mm to obtain a clamp of 4 kN. When the stack 20 is pushed in during its adjustment, the reduction of the clamp is 210 N, that is, a variation of about 5% of the force compared to the set value.

[0082] The problem of the expansion of the tie rod or clamp rod 110 can also be solved. This is because the expansion of a metal rod with a coefficient of expansion of 12×10-6 / °C and a length of 1500 mm from 20°C to 850°C has an expansion of 1500×830×1.2×10-5 = 15 mm. As a result of this variation, an overload of 90 N occurs.

[0083] In this Figure 5, it can also be seen that the adjustment system 100 is fixedly attached to the frame 104 so as to improve its rigidity and includes a second cross-member device 114 traversed by the clamp rod 110. In addition, three free guide elements 120 are present, especially in this second cross-member device 114.

[0084] The free guide element 120 may be a metal workpiece including a central circular recess whose diameter is adjusted to the diameter of the clamp rod 110. This recess is adjusted so that its diameter is very slightly larger than the diameter of the clamp rod 110. In addition, the guide has a certain height to guide well.

[0085] Since it is important to apply the force correctly to the center of the object, such an element is important. The guide makes it possible to properly center the clamp rod at the center of the stack to be adjusted.

[0086] Furthermore, the three stacks 20 are arranged on the base 106 or the manifold 106 to enable gas exchange. At this time, no load is applied to the stack 20 in this representation of Figure 5.

[0087] Advantageously, at this time according to the present invention, thanks to the first cross-member device 108 that gives the same movement to all the springs 112, it becomes possible to impose a common movement on all the springs 112. Again advantageously, in the low temperature region, by using a single independent spring 112 for each stack 20, it becomes possible to control the clamp. By using springs with a large length and low stiffness, it may be possible to apply a substantially constant clamp even when the position of the object to be clamped varies greatly.

[0088] By moving the first cross-member device 108 relative to the frame 104 towards the plurality of stacks 20, it becomes possible to obtain the desired clamp. This adjustment can be carried out under an inert gas, but it is also possible to use other types of gases.

[0089] More specifically, if there is a manifold capable of distributing gas inside each stack 20, it is possible at this time to place the internal volume Vi under air or under an inert gas. On the other hand, if there is no manifold capable of distributing gas inside the stack 20, it is necessary to inactivate the internal volume Vi with an inert gas at this time.

[0090] In FIG. 6, the clamp rod 110 is in contact with the stack 20, but the clamp is not executed. For this purpose, the first cross-member device 108 was lowered until it contacted the first stack 20.

[0091] As shown in FIG. 7, to be able to clamp the stack 20, the first cross-member device 108 is moved downward by a given movement to obtain the desired clamp. The clamp is performed with a imposed movement related to the stiffness of the spring 112. Thus, compressing the spring 112 of 6 N / mm by 800 mm will apply a force of 4000 N.

[0092] When contact is established, the spring 112 extends, and under the influence of this extension, a force proportional to the movement of the first cross-member device 108 is applied to the stack 20.

[0093] This clamping principle according to the present invention has several advantages. For example, if stack 20 is 1 mm higher than another one, at this time the over-clamping received by stack 20 is 6 N, which can be ignored considering that 4000 N is imposed. Similarly, if stack 20 can be pushed in 1 mm more than another one when adjusted, at this time it will receive a 6 N unloading, which can be ignored considering that 4000 N is imposed.

[0094] Also, the thermal expansion of the clamping rod 110 of about 15 mm applies a 90 N overload to stack 20, which can also be ignored considering that 4000 N is imposed, as well as the 35 mm push-in that occurs during adjustment and creates an unloading of about 210 N. Also, the push-in is partially compensated by the expansion.

[0095] To minimize the influence of lateral thermal expansion and the problem of placing the clamping rod 110 centered on stack 20, as shown in the modified embodiment of FIG. 8, a support or leg 124 can be provided in the internal volume Vi of the thermal housing 102.

[0096] The arrangement of the guides is an important point, and depending on their position, especially regarding thermal expansion, the guides can be more or less favorable. The example in FIG. 8 is advantageous as long as the guides are integral with the cross member 114 connected to the frame 104 and the legs 124. Therefore, when the whole system gets hot, everything will expand together, and the support points will remain at the center of the object.

[0097] In particular, in this example, each stack 20 is supported by a support 124 formed through the manifold 106. Each support 124 is preferably connected and fixed to the frame 104 arranged in the low-temperature region. Therefore, the complete mechanical frame 104 is in the low-temperature region together with the guides of the clamping rod 110.

[0098] Generally, it is advantageous to place the frame 104 in a low-temperature region in a manner applicable to any embodiment of the present invention. In fact, if the frame 104 is in a high-temperature region, the resistance of the material will significantly decrease and it will be subjected to forces. At this time, it is necessary to use a much more expensive material and a more robust frame 104, for example, a beam that can withstand at least twice as much force as the higher one. Also, if all elements, the frame 104, the cross member 114, and the elastic return member are in a low-temperature region, there is no problem in centering the workpiece with respect to expansion, and all remain well-aligned.

[0099] Of course, the present invention is not limited to the embodiments described above. Various modifications can be made by those skilled in the art.

[0100] In particular, it should be noted that it is possible to expose the entire oven to an inert gas and operate it without the presence of the manifold 106. At this time, the oven includes a sealed internal muffle, and the joint between the clamp rod 110 and the muffle is made by a bellows.

Explanation of Reference Numerals

[0101] 1 Basic electrolytic cell 2 Cathode 3 Electrolyte 4 Anode 5 Interconnector 50 Cathode chamber 51 Anode chamber 10 Device 11 Oven 12 Loop tube 20 Stack 41 Electrochemical cell 42 Intermediate interconnector 43 Upper end plate 44 Lower end plate 45 Upper clamp plate 46 Lower clamp plate 54 Clamp orifice 55 Clamp stem 56, 57, 58 Clamping means 60 Clamping system 80 Assembly 100 Adjustment system 102 Thermal housing 104 Frame 106 Base, manifold 108 First cross-member device 110 Clamping rod 112 Spring 112a First end 112b Second end 114 Second cross-member device 116 Fixed element 118 Guide and retaining element 120 Free guide element 124 Support

Claims

1. A system (100) for conditioning a plurality of stacks of SOEC / SOFC type solid oxide cells operating at high temperatures, each stack (20) comprising a plurality of electrochemical cells (41) respectively formed of a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnects (42) respectively disposed between two adjacent electrochemical cells (41), the system (100) comprising: A thermal housing (102) delimiting an internal volume (Vi); A plurality of stacks (20) disposed within the internal volume (Vi); Frames (104) disposed on both sides of the thermal housing (102); A first cross member device (108) superimposed on the thermal housing (102) and movably attached to the frames (104) relative to the frames (104); A plurality of clamping rods (110), each stack (20) being associated with one or more clamping rods (110), the clamping rods (110) being attached through the first cross member device (108) and adapted to contact the stack (20) to clamp the stack (20); A plurality of resilient return members (112), each stack (20) being associated with one or more resilient return members (112), each resilient return member (112) being attached around a clamping rod (110), fixed to the clamping rod (110) by a first end (112a) by a fixing element (116), and fixed to the first cross member device (108) by a second end (112b) by a guide and retaining element (118), the clamping rod (110) being supported by the resilient return member (112) such that the clamping rod (110) can be compressed under the influence of the weight of the clamping rod (110); Including; A system (100), characterized in that each stack (20) is associated with a number of resilient return members (112) included between 1 and 10.

2. The system according to claim 1, characterized in that the number of stacks (20) is included between 2 and 100.

3. The system according to claim 1 or 2, characterized in that it comprises a base (106) arranged in the internal volume (Vi) of the hot housing (102), in which the plurality of stacks (20) are arranged.

4. The system according to any one of claims 1 to 3, characterized in that each stack (20) is associated with a single specific elastic return member (112) and a single specific clamping rod (110).

5. The system according to any one of claims 1 to 4, characterized in that the rigidity of each elastic return member (112) is included between 0.1 N / mm and 1000 N / mm, in particular between 1 N / mm and 20 N / mm.

6. The system according to any one of claims 1 to 5, characterized in that the length of each elastic return member (112) is included between 0.1 m and 10 m, in particular between 1 m and 2 m.

7. The system according to any one of claims 1 to 6, characterized in that the system comprises at least one support (124) for the stacks (20), in particular one support (124) for each stack (20), the support (124) being fixed to the frame (104), in particular formed through the base (106) in which the plurality of stacks (20) are arranged.

8. A method for clamping a plurality of stacks (20) of a SOEC / SOFC type solid oxide cell operating at high temperature by means of the adjustment system (100) according to any one of claims 1 to 7, characterized in that it comprises the step of moving the first cross-member device (108) in the direction of the plurality of stacks (20) with respect to the frame (104).

9. The method according to claim 8, characterized in that it is carried out under an inert gas.

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