ASSEMBLY CONSISTING OF A STACK WITH SOLID OXIDES OF THE SOEC/SOFC TYPE AND OF A CLAMPING SYSTEM INTEGRATING A HEAT EXCHANGE SYSTEM

Abstract

An assembly comprising a SOEC/SOFC-type solid oxide stack, and a clamping system for the stack, said clamping system comprising at least two clamping rods that can be used to assemble upper and lower clamping plates. The assembly further comprises a heat exchange system formed at least in part by at least two hollow clamping rods of the clamping system, through which a fluid to be superheated or preheated flows.

Claims

1. Assembly, comprising: a solid-oxide stack of the SOEC/SOFC type functioning at high temperature, comprising: a plurality of electrochemical cells each formed by a cathode, an anode and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnectors each arranged between two adjacent electrochemical cells, a top end plate and a bottom end plate, between which the plurality of electrochemical cells and the plurality of intermediate interconnectors are gripped, a system for gripping the solid-oxide stack of the SOEC/SOFC type, comprising a top clamping plate and a bottom clamping plate, between which the solid-oxide stack of the SOEC/SOFC type is gripped, each clamping plate comprising at least two clamping orifices, the clamping system further comprising: at least two clamping rods intended each to extend through a clamping orifice in the top clamping plate and through a corresponding clamping orifice in the bottom clamping plate to enable the top and bottom clamping plates to be assembled together, clamping means at each clamping orifice of the top and bottom clamping plates intended to cooperate with said at least two clamping rods in order to enable the top and bottom clamping plates to be assembled together, comprising a heat exchange system formed at least partly by at least two hollow clamping rods of the clamping system inside which a fluid to be superheated or preheated circulates, and wherein said at least two hollow clamping rods each comprise an inlet end for a heat-transfer fluid to be preheated and an outlet end for the preheated heat-transfer fluid, and/or wherein that the heat exchange system is a system for superheating the gases at the inlet of the solid-oxide stack of the SOEC/SOFC type, formed at least partly by at least two hollow clamping rods of the clamping system inside which the gases or liquids to be superheated circulate, the assembly comprising an inlet pipe into the stack fluidically connected to at least one hollow clamping rod.

2. Assembly according to claim 1, wherein said at least two hollow clamping rods each comprise an end for the entry of a heat-transfer fluid to be preheated and an end for exit of the preheated heat transfer fluid.

3. Assembly according to claim 2, wherein, at each of the inlet and outlet ends of each clamping rod, the clamping system comprises a force transmission tube, disposed around the corresponding end of the clamping rod, and a clamping washer, the force transmission tube being positioned between the clamping washer and the corresponding clamping plate.

4. Assembly according to claim 2, wherein, at each of the inlet and outlet ends of each clamping rod, the clamping system comprises a thermal-insulation part, disposed around the corresponding end of the clamping rod, the thermal-insulation part being positioned in contact with the corresponding clamping plate.

5. Assembly according to claim 1, wherein the heat exchange system is a system for superheating the gases at the inlet of the solid-oxide stack of the SOEC/SOFC type, formed at least partly by at least two hollow clamping rods of the clamping system inside which the gases or liquids to be superheated circulate, the assembly comprising a pipe for entering the stack fluidically connected to at least one hollow clamping rod.

6. Assembly according to claim 5, wherein the superheating system is of so-called simple mounting, comprising a simple-mounting connection pipe fluidically connecting the inlet pipe and one end of a hollow clamping rod, the other end of the hollow clamping rod being fluidically connected to a pipe for supplying gas to be superheated.

7. Assembly according to claim 5, wherein the superheating system is of so-called mounting in series, comprising a set of pipes for mounting in series, comprising a first pipe for mounting-in-series connection, fluidically connecting a first end of a first hollow clamping rod to a first end of a second hollow clamping rod, and a second pipe for mounting-in-series connection fluidically connecting the second end of the first clamping rod to the pipe for entering the stack, the second end of the second hollow clamping rod being fluidically connected to a pipe for the entry of gas to be superheated.

8. Assembly according to claim 5, wherein the superheating system is of the so-called parallel mounting type, comprising a set of parallel-mounting pipes, comprising a first parallel-mounting connection pipe fluidically connecting a first end of a first hollow clamping rod to a first end of a second hollow clamping rod, and a second parallel-mounting connection pipe fluidically connecting the second end of the first clamping rod to the second end of the second hollow clamping rod, the second parallel-mounting connection pipe being fluidically connected to the pipe for entering the stack by means of a connection pipe itself fluidically connected to the pipe for entering the stack, the first parallel-mounting connection pipe being fluidically connected to a pipe for the entry of gas to be superheated.

9. Assembly according to claim 1, wherein said at least two hollow clamping rods comprise swirl means, for increasing the heat exchange with the fluid to be superheated or preheated.

10. Assembly according to claim 5, wherein the clamping system comprises, at each end of a hollow clamping rod, a clamping washer in contact with a clamping plate.

11. Assembly according to claim 5, wherein the fluid connections between fluid pipes and/or between fluid pipes and hollow clamping rods, are produced by means of one or more demountable fluidtight couplings.

12. Method for manufacturing at least one heat exchange system (40) of an assembly according to claim 1, comprising the step consisting of forming a plurality of hollow clamping rods and fluidically connecting one or more fluid pipes with the hollow clamping rods so as to allow circulation of a fluid inside the hollow clamping rods.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The invention will be able to be understood better from a reading of the following detailed description of non-limitative examples of implementation thereof, as well as from an examination of the schematic and partial figures of the accompanying drawing, on which:

[0081] FIG. 1 is a schematic view showing the operating principle of a high temperature solid oxide electrolyzer (SOEC),

[0082] FIG. 2 is an exploded schematic view of part of a high temperature solid oxide electrolyzer (SOEC) comprising interconnectors according to the prior art,

[0083] FIG. 3 illustrates the principle of the architecture of a furnace on which a high temperature electrolysis stack (SOEC) or fuel cell (SOFC) functioning at high temperature is placed,

[0084] FIG. 4 illustrates the principle of an electrical gas heater according to the prior art,

[0085] FIG. 5 depicts, in perspective, an example of an assembly according to the invention comprising a solid oxide stack of the SOEC/SOFC type and a system for clamping the stack, which may comprise one or more of the heat exchange systems as depicted with reference to FIGS. 6 to 10,

[0086] FIGS. 6 to 10 illustrate partially, schematically and in cross-section, examples of heat exchange systems according to the invention that can be used in an assembly such as the one depicted in FIG. 5, and

[0087] FIG. 11 illustrates, partially in cross-section and in perspective, an example of a demountable fluidtight coupling in the form of a coupling system fluidtight at high temperature for an assembly according to the invention.

[0088] In all these figures, identical references can designate identical or similar elements.

[0089] In addition, the various parts depicted in the figures are not necessarily according to a uniform scale, in order to make the figures more legible.

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

[0090] FIGS. 1 to 4 have already been described previously in the part relating to the prior art and to the technical context of the invention. It is stated that, for FIGS. 1 and 2, the symbols and the arrows for the supply of steam H.sub.2O and the distribution and recovery of dihydrogen H.sub.2, oxygen O.sub.2, air and electric current, are shown for purposes of clarity and information, in order to illustrate the functioning of the devices depicted.

[0091] Furthermore, it should be noted that all the constituents (anode/electrode/cathode) of a given electrochemical cell are preferentially ceramics. The operating temperature of a stack of the high temperature SOEC/SOFC type is moreover typically between 600 and 1000 C.

[0092] In addition, any terms top and bottom are to be understood here according to the normal direction of orientation of a stack of the SOEC/SOFC type when in the configuration of use thereof.

[0093] With reference to FIG. 5, this illustrates an example of an assembly 80 comprising a solid-oxide stack 20 of the SOEC/SOFC type and a clamping system 60, this assembly 80 being able to comprise one or more of the heat exchange systems 40 described hereinafter with reference to FIGS. 6 to 10.

[0094] Advantageously, the assembly 80 according to the invention has a structure similar to that of the assembly described in the French patent application FR 3 045 215 A1, apart from the presence here of a heat exchange system, that is to say this stack 20 has a character of the Plug and Play (PnP) type.

[0095] Thus, in a way that is common to the various embodiments of the invention described hereinafter, and as can be seen in FIG. 5, the assembly 80 comprises a solid-oxide stack 20 of the SOEC/SOFC type functioning at high temperature.

[0096] This stack 20 comprises a plurality of electrochemical cells 41 each formed by a cathode, an anode and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate connectors 42 each arranged between two adjacent electrochemical cells 41. This assembly of electrochemical cells 41 and intermediate interconnectors 42 can also be designated a stack.

[0097] In addition, the stack 20 comprises a top end plate 43 and a bottom end plate 44, also respectively referred to as top stack end plate 43 and bottom stack end plate 44, between which the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42 are gripped, that is to say between which the stack is situated.

[0098] Moreover, the assembly 80 also comprises a system 60 for clamping the solid-oxide stack 20 of the SOEC/SOFC type, comprising a top clamping plate 45 and a bottom clamping plate 46, between which the solid-oxide stack 20 of the SOEC/SOFC type is gripped.

[0099] Each clamping plate 45, 46 of the clamping system 60 comprises four clamping orifices 54.

[0100] In addition, the clamping system 60 further comprises four clamping rods 55, or tie rods, extending through a clamping orifice 54 of the top clamping plate 45 and through a corresponding clamping orifice 54 of the bottom clamping plate 46 to enable the top 45 and bottom 46 clamping plates to be assembled together.

[0101] The clamping system 60 also comprises clamping means 56, 57, 58 at each clamping orifice 54 of the top 45 and bottom 46 clamping plates cooperating with the clamping rods 55 to enable the top 45 and bottom 46 clamping plates to be assembled together.

[0102] More precisely, the clamping means comprise, at each clamping orifice 54 of the top clamping plate 45, a first clamping nut 56 cooperating with the corresponding clamping rod 55 inserted through the clamping orifice 54. In addition, the clamping means comprise, at each clamping orifice 54 of the bottom clamping plate 46, a second clamping nut 57 associated with a clamping washer 58, these cooperating with the corresponding clamping rod 55 inserted through the clamping orifice 54. The clamping washer 58 is situated between the second clamping nut 57 and the bottom clamping plate 46.

[0103] In accordance with the invention, the assembly 80 comprises at least one heat exchange system 40, for example such as the ones described with reference to FIGS. 6 to 10 but not visible in FIG. 5, formed at least partly by a hollow clamping rod 55 of the clamping system 60 inside which a fluid to be superheated or preheated circulates.

[0104] Thus various possibilities of a heat exchange system 40 will now be described with reference to FIGS. 6 to 10.

[0105] First of all, with reference to FIGS. 6, 7 and 8, the heat exchange system 40 may be a system 40 for superheating gases at the inlet to the solid-oxide stack 20 of the SOEC/SOFC type.

[0106] It may thus be formed at least partly by at least one hollow clamping rod 55 of the clamping system 60 inside which the gases GE to be superheated circulate, the assembly 80 moreover comprising an inlet pipe 90 into the stack 20 fluidically connected to at least one hollow clamping rod 55. Advantageously, the superheating system 40 is formed by at least two hollow clamping rods 55, that is to say at least one hollow clamping rod 55 per fluid circuit.

[0107] With reference to FIG. 6, the superheating system 40 may be of the simple mounting type. Thus it comprises a simple mounting connection pipe 91 fluidically connecting the inlet pipe 90 into the stack 20 and an end 55b of a hollow clamping rod 55, the other end 55a of the hollow clamping rod 55 being fluidically connected to a pipe 99 for supplying the gas GE to be superheated.

[0108] As can be seen in FIG. 6, the simple mounting connection pipe 91 may have an angled shape. In addition, the connection between the inlet pipe 90 and the simple mounting connection pipe 91, as well as between the simple mounting connection pipe 91 and the hollow clamping rod 55, and also between the hollow clamping rod 55 and the pipe 99 supplying gas GE to be superheated, can be done by means of a demountable fluidtight coupling 95, as will be described hereinafter, in particular with reference to FIG. 11.

[0109] Furthermore, the clamping rods 55 may be fixed partly to the top 45 and bottom 46 clamping plates by means of clamping means 58 in the form of clamping washers 58.

[0110] In the example in FIG. 6, the simple-mounting superheating system 40 uses only one hollow clamping rod 55 per gas, which therefore generally leads to using two hollow clamping rods, one for each fluid circuit.

[0111] However, in order to increase the superheating of the gases, at least two hollow clamping rods 55, 55 can be used, as described hereinafter with reference to FIGS. 7 and 8. More precisely, FIG. 7 illustrates the case of mounting in series and FIG. 8 illustrates the case of mounting in parallel.

[0112] Thus, with reference to FIG. 7, the superheating system 40 may be mounted in series. It then comprises a set of series mounting pipes 92a and 92b, which comprises a first series mounting connection 92a, fluidically connecting a first end 55a of a first hollow clamping rod 55 to a first end 55a of a second hollow clamping rod 55, and a second series mounting connection pipe 92b fluidically connecting the second end 55b of the first clamping rod 55 to the inlet pipe 90 into the stack 20. In addition, the second end 55b of the second hollow clamping road 55 is fluidically connected to an inlet pipe 99 for gas GE to be superheated.

[0113] As can be seen in FIG. 7, the first series mounting connection pipe 92a and the second series mounting connection pipe 92b may have an angled shape. In addition, the connection between the inlet pipe 90 and the second series mounting connection pipe 92b, and also between the second series mounting connection pipe 92b and the first hollow clamping rod 55, and also between the first hollow clamping rod 55 and the first series mounting connection pipe 92a, and also between the first series mounting connection pipe 92a and the second hollow clamping rod 55, and finally also between the second hollow clamping rod 55 and the pipe 99 for supplying gas GE to be superheated, can be done by means of a demountable fluidtight coupling 95, as will be described hereinafter, in particular with reference to FIG. 11.

[0114] Furthermore, the clamping rods 55 may be fixed partly to the top 45 and bottom 46 clamping plates by means of clamping means 58 in the form of clamping washers 58.

[0115] However, the use of a single hollow clamping rod 5 for simple mounting or two hollow clamping rods 55, 55 for series mounting may have an influence on the thermics of the stack 20. This is because the passage of the gas through the clamping rods locally modifies the temperatures, which may cause a risk of temperature gradients in the plane of the stack 20. Thus it may be possible to use two hollow clamping rods 55, 55 in parallel so as to have less influence on the thermics of the stack 20.

[0116] Thus, with reference to FIG. 8, the superheating system 40 may be of the mounting in parallel type. It comprises a set of mounting pipes in parallel 93a, 93b and 93c, which comprises a first parallel-mounting connection pipe 93a, fluidically connecting a first end 55a of a first hollow clamping rod 55 to a first end 55a of a second hollow clamping rod 55, and a second parallel-mounting connection pipe 93b, fluidically connecting the second end 55b of the first clamping rod 55 to the second end 55b of the second hollow clamping rod 55. In addition, the second parallel-mounting connection pipe 93b is fluidically connected to the inlet pipe 90 in the stack 20 by means of a connection pipe 93c itself fluidically connected to the inlet pipe 90 into the stack 20. Furthermore, the first parallel-mounting connection pipe 93a is fluidically connected to a pipe 99 for supplying gas GE to be superheated.

[0117] As can be seen in FIG. 8, the first parallel-mounting connection pipe 93a and the second parallel-mounting connection pipe 93b may have an angled shape. In addition, the connection between the inlet pipe 90 and the connection pipe 93c, and also between the second parallel-mounting connection pipe 93b and the first hollow clamping rod 55??, and also between the first hollow clamping rod 55 and the first parallel-mounting connection pipe 93a, and also between the first parallel-mounting connection pipe 93a and the second hollow clamping rod 55, and also between the second hollow clamping rod 55 and the second parallel-mounting connection pipe 93b, can be done by means of a demountable fluidtight coupling 95, as will be described hereinafter, in particular with reference to FIG. 11. The inlet pipe 99 for its part may be formed directly on the first parallel-mounting connection pipe 93a.

[0118] Each of the heat exchange systems 40 described above with reference to FIGS. 6 to 8 can make it possible to achieve heating of the gases at the inlet to the stack 20 of the SOEC/SOFC type associated with a furnace 10, as described previously with reference to FIG. 3.

[0119] Moreover, advantageously, the hollow clamping rod or rods 55 can be used to preheat a heat-transfer fluid, liquid or gaseous, intended for another function. Thereby also, the circulation of the heat-transfer fluid in the clamping rod or rods 55 can be used for cooling thereof in order to consolidate the fluidtightness.

[0120] Thus, with reference to FIG. 10, a hollow clamping rod 55 comprises an inlet end 55a for a heat-transfer fluid FE to be preheated and an outlet end 55b for the preheated heat-transfer fluid FS. The passage of the heat-transfer fluid through the hollow clamping rod 55 will cause heating of the fluid and cooling of the hollow clamping rod 55.

[0121] At each of the inlet 55a and outlet 55b ends of the clamping rod 55, the clamping system 60 comprises a force transmission tube 70, disposed around the corresponding end 55a or 55b of the clamping rod 55, and clamping means in the form of a clamping washer 58, the force transmission tube 70 being positioned between the clamping washer 58 and the corresponding clamping plate 45 or 46.

[0122] When the heat-transfer fluid is not related to the use of the stack 20, the flow rate of heat-transfer fluid can be regulated so as to maintain a constant temperature of the clamping rod 55 according to the exothermicity of the stack 20.

[0123] Moreover, the principle of the assembly 80 with its solid-oxide stack 20 of the SOEC/SOFC type makes provision for achieving clamping in the hot zone. However, the passage of a cold heat-transfer fluid through the clamping rod 55 may make it possible to reduce the temperature and thus to be able to offset the clamping out of the cold zone ZF, as illustrated in FIG. 10.

[0124] Moreover, as illustrated in FIG. 9, at each of the inlet 55a and outlet 55b ends of the clamping rod 55, the clamping system 60 may comprise a thermal insulation part 120, in particular made from ceramic, disposed around the corresponding end 55a or 55b of the clamping rod 55. This thermal insulation part 120 is positioned in contact with the corresponding clamping plate 45 or 46.

[0125] The principle of the invention is thus advantageous in enabling the preheating of a heat-transfer fluid, in particular gas. This is because, in SOEC or SOFC mode above the autothermal, the stack 20 is exothermic, it produces heat, and the heat must be discharged in order to limit the rise in temperature of the stack 20. Although some of this heat is discharged by means of thermal losses from the hot zone, the principle of the invention can make it possible to discharge a major part of this heat by preheating a heat-transfer fluid, in particular a gas, entering a hollow clamping rod 55 much colder than the operating temperature, below 200 C. typically.

[0126] This will also have the consequence of reducing the temperature of the clamping rods 55, and therefore increasing their risk of creep, and therefore also increasing the reliability of the clamping system 60. This can therefore make it possible to reduce the cross-section of the clamping rods 55. However, in the case where the heat-transfer fluid would have a tendency to cool the stack 20 excessively, the thermal insulation part 120, preferentially produced from ceramic, can be interposed between a clamping plate 45, 46 of the clamping system 60 and for example a demountable fluidtight coupling 95, as can be seen in FIG. 9.

[0127] Furthermore, as can be seen in all of FIGS. 6, 7, 8 and 10, the hollow clamping rod or rods 55 can advantageously comprise swirl means 98, for increasing the heat exchange with the fluid to be superheated or preheated.

[0128] The presence of swirl means 98 in the hollow clamping rods 55 can make it possible to increase the heat-exchange efficacy. This is because the normal length of a clamping rod 55 may prove to be insufficient to allow the superheating or preheating of a fluid, which may for example correspond to a change from 50 C. to 800 C. for gases to be superheated.

[0129] The swirl means 98 may be in the form of long twisted ribbons inserted in the hollow clamping rods 55 and have the advantage of being simple to install. They make it possible, for the same flow rate, to increase the residence time of the fluid for a given length, while limiting the increase in pressure drop, which is particularly desirable.

[0130] Moreover, FIG. 11 illustrates, partially in cross-section and in perspective, an example of a demountable fluidtight coupling 95 in the form of a coupling system fluidtight at high temperature for an assembly 80 according to the invention. This coupling 95 can make it possible to provide the fluid connections between the fluid pipes 91, 92a, 92b, 93a, 93b, 93c, 90 or 99, or between these fluid pipes 91, 92a, 92b, 93a, 93b, 93c, 90 or 99 and the hollow clamping rods 55, 55. Such a coupling 95 is in particular described in the French patent application No. 17 50009.

[0131] Advantageously, this coupling 95 thus comprises: [0132] a hollow base 101 at least partially threaded F1 on its external surface, referred to as a threaded base, intended to be fixed to a fluid pipe 91, 92a, 92b, 93a, 93b, 93c, 90, 99 or a hollow clamping rod 55, 55, this threaded base 101 comprising an orifice 111 for putting in fluid communication with this fluid pipe or hollow clamping rod, [0133] a hollow base 102 with an at least partially smooth external surface L3, referred as a smooth base, intended to be fixed to another fluid pipe 91, 92a, 92b, 93a, 93b, 93c, 90, 99 or another hollow clamping rod 55, 55, this smooth base 102 comprising an orifice 112 for putting in fluid communication with this fluid pipe or hollow clamping rod, the smooth base 102 and the threaded base 101 each comprising an orifice 111, 112 for putting them in fluid communication with each other, [0134] a threaded nut 103, able to cooperate with the threaded base 101 in order to form a screw/nut system and able to slide with respect to the smooth base 102, the threaded nut 103 comprising, on its internal surface, a first threaded portion 51 cooperating with the thread F1 of the threaded base 101 and a second smooth portion S2 in sliding contact on the smooth external surface L3 of the smooth base 102.

[0135] Naturally, the invention is not limited to the example embodiments that have just been described. Various modifications can be made thereto by a person skilled in the art.