STACK OF SOEC/SOFC SOLID OXIDE CELLS HAVING INNER GUIDING ELEMENTS

Abstract

A stack of SOEC/SOFC solid oxide cells includes a plurality of stacked plates and two guiding elements ensuring that the vertical stacking of at least some of the plates is guided, each plate having two guiding orifices. In a cross-sectional view, the guiding orifices are aligned in a first horizontal direction and are spaced apart by a smaller inter-orifice distance, the guiding elements being spaced apart by a greater smaller inter-element distance and the difference corresponding to the identical inner clearance for the two guiding orifices. The guiding orifices are spaced apart by a larger inter-orifice distance and the guiding elements are spaced apart by a shorter larger inter-element distance, the difference corresponding to the outer clearance, which is greater than the inner clearance.

Claims

1. A stack of SOEC/SOFC-type solid-oxide cells operating at high temperature, consisting of a plurality of plates stacked on top of one another according to a vertical direction substantially perpendicular to each horizontal plane of extent of each plate, the plurality of plates comprising: a plurality of electrochemical cells each formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, a plurality of interconnectors each arranged between two adjacent ones of the electrochemical cells, and an upper end plate and a lower end plate, between which the plurality of electrochemical cells and the plurality of interconnectors are sandwiched, said stack further comprising at least two guiding elements configured to guide at least part of the plates into a vertical stacking, each plate of the at least part of the plates including at least two guiding orifices each opening onto upper and lower faces of each plate and configured to allow passage of the at least two guiding elements, wherein when observed in section in a horizontal plane of extent of each plate of the at least part of the plates, the at least two guiding orifices are aligned according to a first horizontal direction and spaced apart by a smallest inter-orifice distance, the at least two guiding elements being spaced apart by a smallest inter-element distance larger than the smallest inter-orifice distance, and a difference between the smallest inter-element distance and the smallest inter-orifice distance corresponding to an inner clearance being identical for the at least two guiding orifices and the at least two guiding elements, according to the first horizontal direction, the at least two guiding orifices are spaced apart by a largest inter-orifice distance, the at least two guiding elements being spaced apart by a largest inter-element distance smaller than the largest inter-orifice distance, and a difference between the largest inter-orifice distance and the largest inter-element distance, corresponding to an outer clearance, and the outer clearance is larger than the inner clearance.

2. The stack according to claim 1, wherein the inner clearance is comprised between 1 m and 100 m.

3. The stack according to claim 1, wherein the outer clearance is comprised between 0.5 mm and 3 mm.

4. The stack according to claim 1, wherein the outer clearance is identical for the at least two guiding orifices and the at least two guiding elements.

5. The stack according to claim 1, wherein the at least two guiding orifices have a same shape and dimensions.

6. The stack according to claim 5, wherein the at least two guiding orifices have, in section, an oblong shape.

7. The stack according to claim 6, wherein the at least two guiding orifices have, in section, a circular shape.

8. The stack according to claim 6, wherein the at least two guiding orifices have, in section, a polygonal shape.

9. The stack according to claim 1, wherein each plate of the at least part of the plates is square or rectangular shaped and the at least two guiding orifices are diagonally opposite.

10. The stack according to claim 1, wherein the at least two guiding elements are guiding rods having a cylindrical shape.

11. The stack according to claim 1, wherein, when observed in section in a horizontal plane of extent of each plate of the at least part of the plates, a largest guiding orifice dimension of each guiding orifice, according to a second horizontal direction perpendicular to the first horizontal direction, is larger than a largest guiding element dimension of each guiding element, measured according to the second horizontal direction.

12. The stack according to claim 11, wherein a ratio between the largest guiding orifice dimension and the largest guiding element dimension, measured according to the second horizontal direction, is comprised between 1 and 3.

13. A method for packaging a stack of SOEC/SOFC-type solid-oxide cells operating at high temperature according to claim 1, comprising guiding into a vertical stacking at least part of the plates making up the stack using the at least two guiding elements.

14. The method according to claim 13, wherein the guiding comprises preserving a substantially constant gap between the at least two guiding elements and the at least two guiding orifices.

15. The method according to claim 13, wherein the at least two guiding elements are fixed in a packaging base, the method further comprising using materials having the same coefficients of thermal expansion for the plates and a conditioning base.

16. The stack according to claim 8, wherein the at least two guiding orifices have, in section, a square or rectangular shape.

17. The stack according to claim 8, wherein the at least two guiding orifices with the polygonal shape form an angle closest to a centre of the plate being different from 90.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The invention could be better understood upon reading the following detailed description of non-limiting examples of implementation of the latter, as well as upon examining the schematic and partial figures of the appended drawing, wherein:

[0060] FIG. 1 is a schematic view showing the operating principle of a high-temperature solid-oxide electrolyser (SOEC),

[0061] FIG. 2 is an exploded schematic view of a portion of a high-temperature solid-oxide electrolyser (SOEC) comprising interconnectors according to the prior art,

[0062] FIG. 3A and FIG. 3 Bshow, schematically and partially, respectively according to a top view and according to a side view, a principle according to the prior art for guiding the plates of a SOEC/SOFC-type high-temperature stack,

[0063] FIG. 4A and FIG. 4 Bshow, schematically and partially, respectively according to a top view and according to a side view, an example in accordance with the invention for guiding the plates of a SOEC/SOFC-type high-temperature stack,

[0064] FIG. 4C and FIG. 4 Dare respectively enlarged views according to C and D of FIG. 4A,

[0065] FIG. 5 Ashows, schematically and partially, according to a top view, another example in accordance with the invention for guiding the plates of a SOEC/SOFC-type high-temperature stack,

[0066] FIG. 5B is an enlarged view according to B1 of FIG. 5A,

[0067] FIG. 6A shows, schematically and partially, according to a top view, still another example in accordance with the invention for guiding the plates of a SOEC/SOFC-type high-temperature stack, and

[0068] FIG. 6B is an enlarged view according to B1 of FIG. 6A.

[0069] In all these figures, identical references may designate identical or similar elements.

[0070] In addition, the different portions shown in the figures are not necessarily plotted according to a uniform scale, to make the figures more readable.

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

[0071] FIGS. 1 to 3 have already been described before in the part relating to the prior art and to the technical context of the invention. It is specified that, for FIGS. 1 and 2, the symbols and the arrows for steam supply H.sub.2O, for distribution and recovery of dihydrogen H.sub.2, oxygen O.sub.2, air and electric current, are shown for clarity and accuracy purposes, to illustrate the operation of the shown devices.

[0072] Furthermore, it should be noted that all of the constituents (anode/electrolyte/cathode) of a given electrochemical cell are preferably ceramics.

[0073] Moreover, the operating temperature of a SOEC/SOFC-type high-temperature stack is typically comprised between 600 and 1,000 C.

[0074] In addition, any terms upper, lower, horizontal and vertical should be understood herein according to the common direction of orientation of a SOEC/SOFC-type stack when in its use configuration.

[0075] FIGS. 4A to 6B allow illustrating the guidance principle in accordance with the invention.

[0076] First of all, FIGS. 4A to 4D show a first possibility for guiding into a stack the plates P of a stack 20 of SOEC/SOFC-type high-temperature solid-oxide cells, the plates P being positioned on top of one another according to a vertical direction substantially perpendicular to each horizontal plane of extent of each plate P.

[0077] It should be noted that, in all of the examples described herein, a plate P may correspond in particular to an electrochemical cell C1, C2, an interconnector 5, an upper end plate or a lower end plate, or an insulator plate. Preferably, the plate P will generally be an interconnector 5.

[0078] Guidance into a vertical stacking is carried out using two guiding elements 11 and 12, herein in the form of guiding rods or columns. These guiding columns 11, 12 are herein diagonally spaced apart on each square-shaped plate P, but this choice is not restrictive.

[0079] In addition, each plate P includes two guiding orifices O1 and O2 each opening onto the upper face FS and the lower face FI of each plate P. These guiding orifices O1, O2 enable passage of the guiding columns 11, 12. They are also diagonally spaced apart herein on each plate P, but this choice is not restrictive.

[0080] When carrying out packaging of the stack 20, a vertical compressive force is applied on the latter. This force is generally located between the guiding columns 11, 12, which could cause bending of the plates P which are stacked, as schematised by the arrows F in FIG. 3B and herein in FIG. 4B. In case of contact of the plates P with the columns 11, 12, as schematised before in FIG. 3B, an undesirable off-centring phenomenon of AC might occur.

[0081] The configuration proposed in accordance with the invention in FIGS. 4A to 4D is such that, when observed in section in a horizontal plane of extent of each plate P, the guiding orifices O1, O2 are aligned according to a first horizontal direction X and spaced apart by a smallest inter-orifice distance Do1. In addition, the guiding columns 11, 12 are spaced apart by a smallest inter-element distance Dt1 which is larger than the smallest inter-orifice distance Do1.

[0082] The difference between the smallest inter-element distance Dt1 and the smallest inter-orifice distance Do1 corresponds to the inner clearance Jm1. This inner clearance Jm1 is identical at the level of each pair O1, 11 and O2, 12 of guiding orifice and guiding column.

[0083] Moreover, still according to the first horizontal direction X, the guiding orifices O1, O2 are spaced apart by a largest inter-orifice distance Do2, and the guiding columns 11, 12 are spaced apart by a largest inter-element distance Dt2 which is smaller than the largest inter-orifice distance Do2.

[0084] The difference between the largest inter-orifice distance Do2 and the largest inter-element distance Dt2 corresponds to the outer clearance Jm2. Advantageously, this outer clearance Jm2 is larger than the inner clearance Jm1.

[0085] Consequently, bending of a plate P, as schematised by the arrows F in FIG. 4B, will herein be in the direction of facilitating the vertical descent of the latter. Indeed, during bending, the smallest inter-orifice distance Do1, measured according to the first horizontal direction X, namely the distance between the points A.sub.1 and A.sub.1, will decrease because of bending of the plate P, which will tend to free the vertical movement of the plate P because the smallest inter-element distance Dt1, always measured according to the first horizontal distance X, between the two columns 11 and 12 remains constant. Thus, the obtained inner clearance Jm1 (cf. FIG. 4B) will increase in comparison with the clearance Jm1.

[0086] Similarly, the largest inter-orifice distance Do2, namely the distance between the points A.sub.2 and A.sub.2, will also decrease upon bending, as shown in FIG. 4B. However, because of the presence of an outer clearance Jm2 much larger than the inner clearance Jm1, and because the largest inter-element distance Dt2 does not vary, there will be no contact between the plate P and the columns 11, 12, and therefore no jamming or off-centring phenomenon.

[0087] In order to avoid any blockage of the plate P on the columns 11, 12, the inner clearance Jm1 may be comprised between 1 m and 100 m.

[0088] Similarly, the outer clearance J2 may be comprised between 0.5 mm and 3 mm.

[0089] In particular, for a smallest inter-orifice distance Do1 in the range of 300 mm and a plate height H in the range of 0.6 mm, the clearance Jm1 may be larger than 0.6 am to avoid any blockage in a local solid body movement of the plate P. This corresponds to a very small clearance value and therefore enables a very accurate guidance, and thus positioning, of the plate P with respect to the guiding columns 11, 12.

[0090] Advantageously, it should also be noted that the outer clearance J2 is identical for the two guiding orifices O1, O2 and the two guiding columns 11, 12.

[0091] Moreover, in this example of FIGS. 4A to 4B, each of the guiding orifices O1, O2 has, in section, an oblong shape. In this case, the ratio of dimensions between the largest dimension of the guiding orifice do2 of each guiding orifice O1, O2, according to a second horizontal direction Y perpendicular to the first horizontal direction X, namely the distance between the points B.sub.1 and B.sub.2 or between the points B.sub.1 and B.sub.2 in the example of FIGS. 4C and 4D, and the largest guiding element dimension dt2 of each guiding element 11, 12, measured according to the second horizontal direction Y, namely herein the diameter passing through the centre O of the columns 11, 12, as shown in FIGS. 5B and 6B for example, may be too close to 1. In other words, the distances B.sub.1B.sub.2 and B.sub.1B.sub.2 may be substantially equal to the diameter of the columns 11, 12.

[0092] Then, in case of rotation of the plate P according to the first horizontal direction X, there might be an off-centring at the points B.sub.1, B.sub.1, B.sub.2 and B.sub.2 of the oblong shape (cf.

[0093] FIGS. 4C and 4D). In order to avoid this phenomenon, another configuration in accordance with the invention may be proposed.

[0094] Thus, in the example of FIGS. 5A and 5B, the guiding orifices O1, O2 correspond to cylinders whose circular shape in section is larger than that of the columns 11, 12. In other words, the diameter of each guiding orifice O1, O2 is larger than the diameter of each guiding column 11, 12. The guiding orifices O1, O2 are eccentric with respect to the guiding columns 11, 12.

[0095] A tight fit is preserved at the points A.sub.1 and A.sub.1 but the clearances are now larger at the points B.sub.1, B.sub.2, B.sub.1 and B.sub.2.

[0096] Specifically, the largest guiding orifice dimension do2 of each guiding orifice O1, O2, according to the second horizontal direction Y, different herein in the example of FIGS. 5A and 5b of the distance B.sub.1B.sub.2 or B.sub.1B.sub.2, is larger than the largest guiding element dimension dt2 of each guiding column 11, 12, namely herein its diameter passing through the centre O.

[0097] Advantageously, the ratio between the largest guiding orifice dimension do2 and the largest guiding element dimension dt2, measured according to the second horizontal direction Y, is comprised between 1 and 3.

[0098] A third possible configuration of the invention, illustrated in FIGS. 6A and 6B, consists in using guiding orifices 11, 12 with a substantially square shape, larger, and eccentric with respect to the position of the columns 11, 12.

[0099] This configuration describes a principle similar to that of FIGS. 5A and 5B. However, it uses herein V-like shaped contacts (A.sub.1, O, A.sub.2), as shown in FIG. 6B.

[0100] This configuration prevents rotation according to a third vertical direction Z, and still preserves the advantage that the distances A.sub.1A.sub.1 or A.sub.2A.sub.2 are reduced thereby avoiding any contact between the plate P and the column 11, 12 during stacking vertically downwards during the process of packaging the stack 20. Hence, any off-centring problem is avoided. The angle the closest to the centre of the plate P, namely the angle of the two contact planes, may be variable. Advantageously, it is selected so as to be different from 90, in particular larger than this value so as to allow for a little more possibility of rotation according to the directions X and Z.

[0101] During the process of packaging such a stack 20, a substantially constant difference should be preserved between the guiding columns 11, 12 and the guiding orifices O1, O2, in particular during the temperature rise. This difference should be able to remain larger than 0. In order to guarantee this, the thermal expansions governing both the size of the columns 11, 12 and the size of the plates P should be balanced, in particular by a judicious choice of the coefficients of thermal expansion of the used materials, and a temperature field that is as homogeneous as possible over the entire assembly.

[0102] Advantageously, the guiding columns 11, 12 will be fastened in a packaging base and one or more same material(s) will be used for the plates P and for the conditioning base in order to obtain the same coefficients of thermal expansion.

[0103] The invention finds a main application thereof for the assembly of SOEC/SOFC-type high-temperature stacks. In particular, the invention is applicable during the conditioning phase, during which phase the size of the stack decreases considerably because of melting of the glass joints of the assembly as described before in the part relating to the prior art and to the technical context of the invention.

[0104] Of course, the invention is not limited to the embodiments that have just been described. Various modifications may be made thereto by a person skilled in the art.