Assembly comprising a SOEC/SOFC-type solid oxide stack and a clamping system with an integrated gas superheating system

Abstract

An assembly comprising a SOEC/SOFC-type solid oxide stack, and a clamping system for the stack. The assembly further comprises a system for superheating the gases at the inlet of the stack, comprising: a heating plate integrated within the thickness of at least one of the upper and lower clamping plates of the clamping system; an upper or lower end plate for superheating the gases, comprising a circuit through which the gases to be heated flow; and an inlet duct for the gases to be heated.

Claims

1. Assembly, including: a SOEC/SOFC-type solid oxide stack operating at high temperature, including: a plurality of electrochemical cells each formed of a cathode, an anode and an electrolyte inserted between the cathode and the anode, and a plurality of intermediate interconnectors each arranged between two adjacent electrochemical cells, an upper end plate and a lower end plate, between which the plurality of electrochemical cells and the plurality of intermediate interconnectors are clamped, a system for clamping the SOEC/SOFC-type solid oxide stack, including an upper clamping plate and a lower clamping plate, between which the SOEC/SOFC-type solid oxide stack is clamped, wherein it further includes: a system for superheating the gases at the input of the SOEC/SOFC-type solid oxide stack, including: at least one heating plate integrated in the thickness of at least one of the upper and lower clamping plates suitable for heating the gases to be heated, at least one upper gas superheating end plate, positioned between the upper clamping plate and the SOEC/SOFC-type solid oxide stack, and/or a lower gas superheating end plate, positioned between the lower clamping plate and the SOEC/SOFC-type solid oxide stack, each gas superheating end plate including a gas circulation circuit from a first end, where the gases to be heated arrive, to a second end, where the heated gases are discharged towards the stack, at least one input duct of the gases to be heated communicating with the first end of a gas superheating end plate, such that a stream of gas to be heated entering said at least one input duct circulates in the gas circulation system, from the first end to the second end to reach the input of the SOEC/SOFC-type solid oxide stack.

2. Assembly according to claim 1, wherein the gas circulation circuit extends in a sinusoidal shape from the first end to the second end.

3. Assembly according to claim 1, wherein said at least one upper gas superheating end plate and/or said at least one lower gas superheating end plate are respectively positioned between the upper clamping plate and the upper end plate, and between the lower clamping plate and the lower end plate.

4. Assembly according to claim 3, wherein the gas superheating end plate(s) are positioned between two electrical insulation plates.

5. Assembly according to claim 1, wherein said at least one upper gas superheating end plate and/or said at least one lower gas superheating end plate are respectively formed by the upper end plate and the lower end plate, which include a gas circulation circuit from a first end, where the gases to be heated arrive, to a second end, where the heated gases are discharged to the stack.

6. Assembly according to claim 5, wherein each gas superheating system includes two closing plates on either side of the upper gas superheating end plate and/or the lower gas superheating end plate, to close the gas circulation circuit.

7. Assembly according to claim 1, wherein the gas superheating system further includes at least one output duct for recovering the gases at the SOEC/SOFC-type solid oxide stack output.

8. Assembly according to claim 1, wherein each clamping plate of the clamping system includes at least one clamping orifice the clamping system further including: at least one clamping rod intended to extend through a clamping orifice of the upper clamping plate and through a corresponding clamping orifice of the lower clamping plate to enable the assembly of the upper and lower clamping plates with one another, clamping means at the level of each clamping orifice of the upper and lower clamping plates intended to engage with said at least one clamping rod to enable the assembly of the upper and lower clamping plates with one another, at least one electrical insulation plate intended to be situated between the SOEC/SOFC-type solid oxide stack and at least one of the upper and lower clamping plates.

9. Method for manufacturing at least one system for superheating the gases at the input of a SOEC/SOFC-type solid oxide stack of an assembly according to claim 1, wherein it includes the step of machining a lower gas superheating end plate and/or an upper gas superheating end plate to form a gas circulation circuit.

10. Method according to claim 9, wherein it includes the step consisting of mounting, by means of a transparent laser welding method, two closing plates on the circulation circuit on either side of the lower gas superheating end plate and/or the upper gas superheating end plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention may be understood more clearly on reading the following detailed description of non-limiting embodiment examples thereof, as well as on examining the schematic and partial figures of the appended drawing, wherein:

(2) FIG. 1 is a schematic view showing the operating principle of a high-temperature solid oxide electrolyser cell (SOEC),

(3) FIG. 2 is an exploded schematic view of a part of a high-temperature solid oxide electrolyser cell (SOEC) comprising interconnectors according to the prior art,

(4) FIG. 3 illustrates the principle of the architecture of a furnace whereon a high-temperature electrolyser cell (SOEC) or fuel cell (SOFC) stack operating at high temperature is placed,

(5) FIG. 4 illustrates the principle of an electric gas heater according to the prior art,

(6) FIG. 5 represents, in a perspective view, a first example of an assembly according to the invention comprising a SOEC/SOFC-type solid oxide stack and a system for clamping the stack, further comprising two gas superheating systems, in the upper position and in the lower position respectively, with the gas superheating end plate of each system set between the stack end plate and the clamping plate,

(7) FIG. 6 represents, in a perspective view, a second example of an assembly according to the invention comprising a SOEC/SOFC-type solid oxide stack and a system for clamping the stack, further comprising two gas superheating systems, in the upper position and in the lower position respectively, with the gas superheating end plate of each system integrated in the stack end plate design,

(8) FIGS. 7 and 8 are partial perspective and cross-sectional views of the second example of an assembly in FIG. 6, without the presence of the stack,

(9) FIG. 9 represents, in a perspective view, an example of a gas superheating end plate of an assembly according to the invention, optionally separate from the stack end plate as according to the example in FIG. 5 or integrated in the stack end plate as according to the example in FIG. 6, and

(10) FIG. 10 represents the gas superheating end plate in FIG. 9 with the presence of a closing plate mounted by laser welding.

(11) Throughout these figures, identical references may denote identical or equivalent elements.

(12) Furthermore, the different parts represented in the figures are not necessarily on a uniform scale, in order to render the figures more readable.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

(13) FIGS. 1 to 4 have already been described above in the section relating to the state of the related art and the technical context of the invention. It is specified that, for FIGS. 1 and 2, the symbols and arrows in respect of the supply of steam H.sub.2O, distribution and recovery of dihydrogen H.sub.2, oxygen O.sub.2, air and electric current, are shown for purposes of clarity and precision, to illustrate the operation of the devices represented.

(14) Furthermore, it should be noted that all the constituents (anode/electrolyte/cathode) of a given electrochemical cell are preferentially ceramic. The operating temperature of a high-temperature SOEC/SOFC-type stack is moreover typically between 600 and 1000° C.

(15) Furthermore, the optional terms “upper” and “lower” are to be understood herein to refer to the normal orientation of a SOEC/SOFC-type stack when in the configuration of use thereof.

(16) With reference to FIG. 5, a first example has been illustrated of an assembly 80 comprising a SOEC/SOFC-type solid oxide stack 20 according to the invention and a clamping system 60, further comprising two gas superheating systems 40, in the upper position and in the lower position respectively, with the gas superheating end plate 65, 66 of each system set between the stack end plate 43, 44 and the clamping plate 45, 46.

(17) Moreover, with reference to FIGS. 6, 7 and 8, a second example has been illustrated of an assembly 80 comprising a SOEC/SOFC-type solid oxide stack 20 according to the invention and a clamping system 60, further comprising two gas superheating systems 40, in the upper position and in the lower position respectively, with the gas superheating end plate 43, 44 corresponding to the stack end plate 43, 44.

(18) In other words, it is therefore possible to implement the invention according to these two embodiments: the first, wherein the gas superheating end plate 65, 66 is pressed between a clamping plate 45, 46 and a stack end plate 43, 44; the second, wherein the gas superheating end plate corresponds directly to a stack end plate 43, 44, the gas circulation circuit, a single-channel circuit, being integrated in this stack end plate 43, 44.

(19) Each superheating system 40 makes it possible to heat the gases at the input of the SOEC/SOFC-type stack 20 associated with a furnace 10, as described above with reference to FIG. 3.

(20) Among the various heat transfer modes in the area of the furnace 10, the predominant mode at these temperature levels, i.e. between 650 and 800° C., corresponds to radiant heat exchanges due to radiation. The other transfer mode is then thermal conduction, and this is used by the invention as it has the advantage of creating less external heat loss. It consists of the heat transfer mode induced by a difference in temperature between two regions of the same medium or between two media in contact without appreciable material displacement. The use of heating plates 61, as described hereinafter, for the superheating systems 40 makes it possible to recover the thermal conduction and raise the gases to the correct temperature. Thus, the gases circulating in the gas circulation circuit are heated by means of a heating plate 61 by thermal conduction.

(21) Advantageously, the assembly 80 according to the invention has a similar structure to that of the assembly described in the French patent application FR 3 045 215 A1, apart from the presence herein of a gas superheating system, i.e. the stack 20 has a Plug & Play (PnP) feature.

(22) Also, in a manner common to both embodiments of the invention, and as seen in FIGS. 5 to 8, each assembly 80 includes a SOEC/SOFC-type solid oxide stack 20 operating at high temperature.

(23) This stack 20 includes a plurality of electrochemical cells 41 each formed of a cathode, an anode and an electrolyte inserted between the cathode and the anode, and a plurality of intermediate interconnectors 42 each arranged between two adjacent electrochemical cells 41, This assembly of electrochemical cells 41 and intermediate interconnectors 42 may also referred to as “stack”.

(24) Furthermore, the stack 20 includes an upper end plate 43 and a lower end plate 44, respectively also referred to as upper stack end plate 43 and lower stack end plate 44, between which the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42 are clamped, i.e. between which the stack is situated.

(25) Moreover, the assembly 80 also includes a system 60 for clamping the SOEC/SOFC-type solid oxide stack 20, including an upper clamping plate 45 and a lower clamping plate 46, between which the SOEC/SOFC-type solid oxide stack 20 is clamped,

(26) Each clamping plate 45, 46 of the clamping system 60 includes four clamping orifices 54.

(27) Furthermore, the clamping system 60 includes four clamping rods 55 extending through a clamping orifice 54 of the upper clamping plate 45 and through a corresponding clamping orifice 54 of the lower clamping plate 46 to enable the assembly of the upper 45 and lower 46 clamping plates with one another.

(28) The clamping system 60 further includes clamping means 56, 57, 58 at the level of each clamping orifice 54 of the upper 45 and lower 46 clamping plates engaging with the clamping rods 55 to enable the assembly of the upper 45 and lower 46 clamping plates with one another.

(29) More specifically, the clamping means include, at the level of each clamping orifice 54 of the upper clamping plate 45, a first clamping nut 56 engaging with the corresponding clamping rod 55 inserted through the clamping orifice 54. Furthermore, the clamping means include, at the level of each clamping orifice 54 of the lower clamping plate 46, a second clamping nut 57 associated with a clamping washer 58, engaging 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 lower clamping plate 46.

(30) Moreover, according to the invention, the assembly 80 further includes an upper gas GS superheating system 40 and a lower gas GS superheating system at the input of the SOEC/SOFC-type solid oxide stack 20.

(31) Each upper or lower superheating system 40 includes a heating plate 61 integrated in the thickness of the upper 45 or lower 46 clamping plate so as to enable the heating of the gases to be heated GE.

(32) Furthermore, each supper or lower superheating system 40 includes an upper or lower gas superheating end plate. The upper gas superheating end plate 65, 43 is positioned between the upper clamping plate 45 and the SOEC/SOFC-type solid oxide stack 20, the lower gas superheating plate 66, 44 is positioned between the lower clamping plate 46 and the SOEC/SOFC-type solid oxide stack 20.

(33) More specifically, with reference to FIG. 5, the first embodiment envisages that the gas superheating end plate 65, 66 is independent from the stack end plate 43, 44.

(34) Thus, the upper gas superheating end plate 65 is situated between the upper end plate 45 and the upper stack end plate 43. Similarly, the lower gas superheating end plate 66 is situated between the lower clamping plate 46 and the lower stack end plate 44.

(35) Advantageously, each gas superheating end plate 65, 66 is set between two electrical insulation plates 59, made of mica. These electrical insulation plates 59 act as electrical insulation shims. In the absence thereof, the clamping system being preferentially metallic, it would induce a general short-circuit between the top and the bottom of the stack 20.

(36) On the other hand, with reference to FIGS. 6 to 8, the second embodiment envisages that the gas superheating end plate corresponds to the stack end plate 43, 44. In other words, the gas circulation circuit C is formed in the usual stack end plate 43, 44.

(37) This type of stack end plate 43, 44 conventionally has two functions: sandwiching the stack; receiving the stack input/output ducts, as well as the thermocouples, particularly at the level of the lower stack end plate 44.

(38) Thus, the second embodiment of the invention adds thereto the function of using this plate for superheating the gases at the stack input.

(39) It should that each stack end plate 43, 44 and/or each gas superheating end plate 65, 66 may be made for example of high-temperature ferritic stainless steel, such as Crofer® 22 APU.

(40) In the two embodiments, respectively according to FIG. 5 and according to FIGS. 6 to 8, the upper gas superheating end plate 43 or 65 is identical to the lower gas superheating end plate 44 or 66. However, it could be otherwise. The geometry of the plates may be modified according to needs but their operating principle remains the same.

(41) Thus, as seen particularly in FIGS. 8 and 9, the gases to be heated GE enter an input duct 62 and reach the first end P1 of a single-channel gas circulation circuit C of the gas superheating end plate 65, 43. FIG. 9 represents the upper gas superheating end plate 65 or 43 but the principle is the same for the lower gas superheating end plate 66 or 44.

(42) Once at the level of the first end P1, the gases follow the path in a sinusoidal, or coil, shape of the circulation circuit C as according to the arrows F shown in FIG. 9 until they reach the second end P2 where the heated gases GS, via the heating plate 61, are discharged to the stack 20. The total length travelled by the gases in the circulation circuit C, in other words the length between the first P1 and second P2 ends, is for example of the order of 2 m. By way of example, the head loss calculated with respect to this configuration is of the order of 81 mbar for a channel of 5 mm×5 mm over a length of 2 m.

(43) As a general rule, the length of the gas circulation circuit, i.e. the total length travelled in the circulation circuit C, between the first P1 and second P2 ends, may be determined according to the nature and the velocity of the gases circulating therein, as well as the internal temperature of the tube. This length may for example be more generally between 2 and 3 m, regardless of the embodiment described.

(44) The overall shape of the circulation circuit C, i.e. the overall shape of the enclosure wherein the circulation circuit C is contained, may be of any type, being for example square, rounded or indeed rectangular as is the case for the example in FIG. 9 with an upper gas superheating end plate 43 or 65 also of rectangular shape.

(45) The circulation circuit C may be obtained by machining, for example by means of a numerical control mill or any other suitable machining system in order to obtain the desired geometry. In any case, the cross-section of the single channel forming the circulation circuit C and the length thereof must be optimised to superheat the gases correctly while minimising head losses.

(46) Moreover, as seen in FIGS. 8 and 9 in particular, each gas GS superheating system 40 includes a gas recovery output duct TS at the output of the SOEC/SOFC-type solid oxide stack 20, through the corresponding gas superheating end plate.

(47) Furthermore, in the first embodiment of the invention according to the example in FIG. 5, no closure of the upper 65 and lower 66 gas superheating end plates is needed as two electrical insulation plates 19, made of mica, are positioned on either side of each gas superheating end plate 65 and 66, namely a plate for closing the channels of the upper and lower stack end plate, and the other plate for the electrical insulation.

(48) The mica of the electrical insulation plates 19 is traditionally used as an electrical and thermal insulator. The thermal insulation plates 19 may preferentially have a thin layer of mica, particularly of the order of 0.8 mm. In this case, the mica may make it possible to electrically insulate the stack, without for all that forming a heat transmission barrier.

(49) On the other hand, in the second embodiment of the invention according to the example in FIGS. 6 to 8, each superheating system 40 includes at least one closing plate 48 particularly two closing plates 48 on either side of the gas superheating end plate 43 or 44, to close the circulation circuit C, as seen in FIG. 10.

(50) The closing plate(s) 48 are preferentially mounted by transparent laser welding. The laser welding technique is used for welding metals using the characteristics of laser technology: with the high energy density and fineness of the laser beam, the targeted zones start to melt and are then rapidly welded by cooling. This results in a strong weld on a reduced surface area.

(51) As illustrated in FIG. 10, the transparent laser welding should preferentially follow the contour Ct, or laser seal line, as shown to be able to force the gases to follow the full path.

(52) In this example in FIGS. 6 to 8, electrical insulation plates may also be envisaged to set the polarities.

(53) Obviously, the invention is not limited to the embodiment examples described above. Various modifications may be made thereto by those skilled in the art.