Cell stacking unit for electrochemical devices, especially for SOEC or SOFC

Abstract

The invention relates to a stacking unit (SRU) for a SOEC or SOFC type electrochemical device, said unit comprising at least two interconnector plates (3) between which at least one fluid flows, and comprising: an inlet (5) through which the fluid is injected into said unit, an intermediate portion (6) comprising a cell (4) in which the fluid is in contact with said cell (4), and an outlet (7) through which the fluid is discharged. The unit includes at least one fluid diffuser (8), positioned between said inlet and said intermediate portion, and / or between the intermediate portion and the outlet, the fluid diffuser comprising at least one distribution device (9) positioned upstream of the cell and / or downstream of the cell, and ensuring either the distribution of the fluid or the collection of the fluid over the entire length of the cross-section of the intermediate portion. Figure for the abstract: [Fig. 1]

Description

Title of the invention: Cell stacking unit for electrochemical devices, in particular for SOEC or SOFC. Technical field

[0001] The invention relates to the field of electrochemical devices of the electrolyzer type and finds applications in particular in the sectors of renewable energy production and cogeneration.

[0002] The invention is of particular, but not limiting, interest in devices implementing a high-temperature electrolysis process, that is to say typically a temperature between 100°C and 850°C, in particular devices known under the Anglo-Saxon name "Solid Oxide Electrolysis Cell (SOEC)" or "Solid Oxide Fuel Cell (SOFC)".

[0003] The invention relates more specifically to the realization of a recurring unit, in a stack of electrolyzer cells. State of the art

[0004] An electrochemical device can be implemented for high-temperature electrolysis and comprise a stack of solid oxide electrolyzer cells or SOECs (solid oxide electrolyzer cell in Anglo-Saxon terminology) or as a fuel cell and comprise a stack of solid oxide fuel cells or SOFCs (Solid oxide fuel cell in Anglo-Saxon terminology).

[0005] Such a device comprises a module (or “stack” in Anglo-Saxon terminology) consisting of a stack of electrochemical cells clamped between two clamping plates. The cells are electrically connected in series by means of interconnecting elements.

[0006] SOEC technology is based on the stacking of Single Repeat Units (SRUs), also referred to as the "unit" hereafter. One of the functions of the unit is to supply / extract fuel to the anode and extract oxygen from the cathode.

[0007] The spatial uniformity of the distribution of these gases towards the electrodes is important, because it is linked to the uniformity of the electrochemical reaction and therefore to the longevity of the cells.

[0008] Various solutions have been imagined and implemented to ensure good gas distribution: one solution, for example, proposes to use a constriction to create pressure loss in certain areas of the stack (pressure loss due to fluidic friction).

[0009] The invention aims to promote the proper distribution of flows through a unit (an SRU) between the inlet and outlet of the SRU, the inlet and outlet of the SRU being achieved by sections smaller than the intermediate section (between the entrance and exit of the SRU) which is larger.

[0010] The invention aims to provide a solution for the flow entering the SRU to be distributed homogeneously over the entire intermediate section of the SRU (or section facing the active area) for optimal cell operation. Description of the invention

[0011] The invention proposes a cell stacking unit for an SOEC or SOFC type electrochemical device, said unit comprising at least two interconnector plates between which at least one fluid flows, and comprising: - an inlet through which the fluid is injected into said unit (this inlet is the inlet through which the fluid is distributed between the SRUs), said inlet having an inlet cross-section, - an intermediate part comprising a cell and in which the fluid is in contact with said cell, said intermediate part having a cross-section that is larger than the inlet cross-section, and - an outlet through which the fluid is discharged, said outlet having a fluid outlet section.

[0012] It should be noted that the intermediate part is located between an upstream zone and a downstream zone which are used, according to the invention, to homogenize the circulation of the fluid between the inlet and the cell and / or between the cell and the outlet.

[0013] The unit according to the invention is remarkable in that it comprises at least one fluid diffuser, positioned between said inlet and said intermediate part, and / or between the intermediate part and the outlet, the fluid diffuser comprising at least one distribution device positioned upstream of the cell and / or downstream of the cell and respectively ensuring either the distribution of the fluid or the collection of the fluid over the entire length of the section of the intermediate part.

[0014] The presence of the diffuser in the unit according to the invention, positioned upstream and / or downstream of the intermediate section, allows control of the direction taken by the fluid before it enters the intermediate section, and / or at the outlet of the intermediate section (containing the cell), thus making it possible to impose a chosen distribution for the fluid within the unit. The direction of the fluid can therefore be homogenized, or concentrated at a desired point at the inlet or outlet of the intermediate section, to promote fluid circulation.

[0015] According to the invention, the unit may comprise the following features, taken separately or in combination:

[0016] - the unit may comprise at least two diffusers, each positioned respectively upstream of the intermediate section and downstream of the intermediate section,

[0017] - said diffuser distribution device may include a comb comprising parallel teeth extending along the entire length of the intermediate section, the orientation of the teeth ensuring a direction of fluid flow through channels towards said cell,

[0018] - the comb may have teeth of different thicknesses, the thickness of the teeth increasing between a first end of the section and a second end of the section, the difference in thicknesses defining channels of different fluidic cross-section,

[0019] - according to one embodiment, the width of the channels increases between said of said first end of intermediate cross-sectional length and said second end of intermediate cross-sectional length, ensuring a more difficult passage of fluid at said first end than at said second end,

[0020] - advantageously, said teeth of the comb are oriented along a direction inclined with respect to an axial direction of the unit, said axial direction of the unit being parallel to a median direction of the cell,

[0021] - preferably, said fluid diffuser further comprises at least one element deflector upstream of the distribution device, ensuring the orientation of the fluid from the unit inlet towards the intermediate section and towards said distribution device, along a direction or a set of predetermined directions over the entire cross-section of the intermediate section,

[0022] - furthermore, said deflector element comprises a guide of variable cross-section, which extends between the unit inlet and said intermediate section, said variable section enlarging between the unit inlet and the section of the intermediate part upstream of the distribution device,

[0023] - preferably, said deflector element comprises a section guide variable, which extends between said intermediate part and the outlet, said variable section narrowing between the intermediate part and the outlet, downstream of the distribution device,

[0024] - advantageously, said deflector element comprises protruding studs which extend between the two interconnector plates,

[0025] - the protruding studs may have a round cross-section,

[0026] - the protruding studs may have a petal-shaped cross-section,

[0027] - the pads can be positioned in the vicinity of the unit's inlet,

[0028] - furthermore, the studs are uniformly distributed in said deflector element,

[0029] - the distribution device and / or the deflector element of the diffuser device is / are manufactured by stamping an interconnector plate,

[0030] - the distribution device and / or the deflector element of the diffuser device is / are made, alternatively, independently of the interconnector plates and in that it is / are attached and fixed to an interconnector plate. Brief description of the figures

[0031] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0032] [Fig-1]: [Fig.1] is a top view of an SRU unit, represented schematically;

[0033] [Fig.2] : [Fig.2] is a cross-sectional view along plane AA mounted in [Fig.1].

[0034] [Fig.3]: [Fig.3] shows a fluid diffuser comprising a unit conforming to a first embodiment of the invention,

[0035] [Fig.4]: [Fig.4] shows a fluid diffuser comprising a unit according to a second embodiment of the invention,

[0036] [Fig.5]: [Fig.5] shows a fluid diffuser comprising a unit according to a third embodiment of the invention,

[0037] [Fig.6]: [Fig.6] shows a fluid diffuser comprising a unit according to a fourth embodiment of the invention,

[0038] [Fig.7]: [Fig.7] shows a fluid diffuser comprising a unit according to a fifth embodiment of the invention,

[0039] [Fig.8]: [Fig.8] shows a fluid diffuser comprising a unit according to a sixth embodiment of the invention and

[0040] [Fig.9]: [Fig.9] shows a fluid diffuser comprising a unit according to a seventh embodiment of the invention

[0041] It is understood that the embodiments described below are not exhaustive. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0042] In particular, all the variants and all the embodiments described are combinable with each other if nothing prevents this combination from a technical point of view.

[0043] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description

[0044] The SRU units referred to in this description are cell stacking units for SOEC or SOFC type electrochemical devices.

[0045] Fig. 1 shows an SRU unit according to a first embodiment of the invention, in top view: fluid inlet lines are observed, for example fuel for inlet line 1 and air for inlet line 2, and fluid outlet lines: an outlet line 10 for fuel and an outlet line 20 for air 20.

[0046] We also observe on [Fig.1] an interconnector plate 3 and, in the center of the SRU, a cell 4 symbolized by a square, which is brought into contact on one of its faces with the fuel and on the other face with the air.

[0047] The plates are sheets of specific ferritic material (K41 for example), with a thickness between 0.2 and 1 mm, which have been laser cut, and possibly stamped.

[0048] Fig. 2 shows the same SRU unit, seen in section: it can be seen that cell 4 is positioned between two interconnector plates 3 and that, between cell 4 and the upper interconnector plate 3, there is a channel 11 in which the fuel flows and that, between cell 4 and the lower interconnector plate 3, there is a channel 21 in which the air flows.

[0049] The fuel and air do not meet, even if the two fluids flow in the same direction, because the fuel and air circulation channels are isolated and sealed from each other: the fuel flows above cell 4 in channel or channels 11 while the air flows in channel or channels 21 below cell 4.

[0050] In [Fig.1], it can be seen that the SRU unit comprises a fuel circulation stage in solid lines and an air circulation stage in dashed lines.

[0051] For each stage, the SRU unit comprises an inlet 5, through which fuel or air is injected, said inlet having an inlet section SL

[0052] It also includes an intermediate part 6, which includes cell 4 and in which the fuel is brought into contact with cell 4.

[0053] The intermediate part 6 having an intermediate part section S2 which is larger than the inlet section SL

[0054] The SRU unit finally includes an outlet 7 through which the fuel, or air, is discharged, said outlet 7 having an outlet section which has dimensions similar to the inlet section SL

[0055] For each stage in the SRU unit and in accordance with the invention, the unit includes a fluid diffuser 8 which is positioned between said inlet 5 and said intermediate part 6 (see [Fig.1]).

[0056] We observe, on [Fig.2], that each of the stages actually comprises a first fluid diffuser 8 positioned between the inlet 5 and the intermediate part 6 and a second diffuser 8' which is positioned between the intermediate part 6 and the outlet 7.

[0057] The lower stage, which ensures air circulation between duct 2 and duct 20, also includes two fluid diffusers, in a similar manner to the first stage of fuel circulation.

[0058] Different diffuser designs are shown in figures 3 to 9 and each of them will now be presented.

[0059] The diffuser 8 shown in [Fig.3] is the one implemented in the example shown in figures 1 and 2.

[0060] The diffusers 8 illustrated in each of the figures 3 to 9 all comprise a distribution device 9 and a deflector element 90 upstream of the distribution device.

[0061] If the diffuser 8 is positioned between the intermediate part 6 and the outlet 7, the deflector element is positioned downstream of the distribution device, between the intermediate part 6 and the outlet, also downstream of the distribution device 9.

[0062] The diffusers shown in figures 3 to 9 can each be positioned either upstream of the intermediate part, being oriented in one direction, or downstream of the intermediate part, being oriented in the opposite direction.

[0063] The embodiment of [Fig.3] includes a distribution device 9, positioned upstream of the cell (when positioned between the inlet 5 and the intermediate part 6).

[0064] The distribution device 9 ensures the distribution of the fluid (fuel or air) over the entire length L of the section S2 of the intermediate part 6.

[0065] The distribution device 9 comprises a comb-shaped structure 81, having teeth 82 which are parallel to each other and which extend over the entire length L of the cross-section of the intermediate part. The orientation of the teeth ensures a direction of fluid flow through channels 83 towards said cell 4 (see [Fig. 3]).

[0066] In the embodiment shown in [Fig. 3], all the teeth 82 are identical. It should be understood that the teeth of the comb 81 could be different without departing from the scope of the invention.

[0067] For example, in [Fig.9], the teeth 82 of the distribution device are of different thicknesses: more particularly, the thickness of the teeth 82 increases between a first end El of length L with intermediate section 6 and a second end E2 of length L with intermediate section 6.

[0068] This defines channels 83 between the teeth 82 which have different widths.

[0069] In the context of the example shown in [Fig.9], when the fluid diffuser is oriented in this direction and positioned upstream of the intermediate part 6 comprising the cell 4; the width of the channels 83 increases between the first end El and the second end E2, which makes the passage of the fluid easier in front of the inlet 5: the fluid will therefore, preferably, infiltrate between the teeth 82 which are far from the inlet 5, near the second end E2.

[0070] In the examples shown in [Fig.3] or in [Fig.6], it is also observed that the diffuser 8 includes a deflector element 90.

[0071] The deflector element 90 is located upstream of the distribution device 9 if the diffuser is positioned between the inlet 5 and the intermediate part.

[0072] This deflector element 90 ensures the orientation of the fluid from the inlet 5 towards the intermediate part 6 and, consequently, towards said distribution device 9.

[0073] Depending on the shape of the deflector element 90, the fluid (fuel or air) is oriented along a direction D or along a bundle of predetermined directions over the entire section S2 of the intermediate part 6.

[0074] In accordance with the invention and to ensure its guiding function, the deflector element 90 comprises a guide of variable section, which extends between the inlet of the unit and said intermediate part, said variable section enlarging between the inlet of the unit and the section of the intermediate part upstream of the distribution device.

[0075] Several examples of variable cross-section guide shapes are illustrated in Figures 3 to 9: all the guides 90 shown have a variable cross-section that increases between the inlet and the intermediate section. It should be understood that the deflector guide 90 can have a variable cross-section that, conversely, decreases if the diffuser is placed between the intermediate section 6 and the outlet 7 of the unit.

[0076] Figure 3 shows a deflector 90 which includes a guide of triangular section: - one side of which extends between the inlet 5 of the unit and the first end El of intermediate section, - of which a second side extends between the first end El and the second end E2 with a cross-sectional length of intermediate part, and - of which a third side extends between said second end E2 and the entrance.

[0077] Figure 9 also shows a deflector element with a guide that is substantially triangular in shape. However, in the vicinity of end E2, the guide has a channel-shaped portion that extends over a partial length L1 of the length L of section S2.

[0078] The diffuser examples in Figures 4, 5 and 8 also include a guide, part of which forms a channel over a length L1 in the vicinity of the second end E2.

[0079] Fig. 7 shows a diffuser whose deflector element guide is triangular in shape, part of which is truncated near the end E2 by the length of the section of the intermediate part 6.

[0080] The distribution device is, in the context of this example, made by a rod which extends over the entire length L of the section of the intermediate part 6, the rod being able to have one or more openings (not illustrated) to allow the flow of fluid to pass between the guide of the deflector element 90 and the intermediate part 6 comprising the cell 4.

[0081] It is noted that the guide of the deflector element 90 includes projecting studs 91 with a round cross-section, which obstruct the passage of the fluid, so as to create a disturbance in the flow of the fluid in the guide. The studs 91 with a round cross-section can, for example, extend between the two interconnector plates.

[0082] In this example, the pads 91 are positioned in the vicinity of the inlet 5 of the unit. They are uniformly distributed in the guide of the deflector element 90.

[0083] The protruding studs could have another shape of section without going out of the scope of the invention: in particular, as can be seen in [Fig.8], the studs could have a petal-shaped section 92 and be distributed around (or at least partially around) the conduit 1 at the inlet 5 of the unit.

[0084] For example, in [Fig.5], we observe a cap-shaped stud 93, which partially borders the conduit 1, which forces the flow to exit towards the round-section studs 91, which surround the conduit 1 where the cap is not present.

[0085] Figures 4 and 6 also show deflectors which have petal-shaped cross-section studs 92 which are distributed at least partially around the conduit 1.

[0086] The shape and size of the petal-shaped section pots 92 can also vary without going out of the scope of the invention.

[0087] Other embodiment variants could also be considered: for example, in [Fig.4], it can be seen that the distribution device could also include several rows of teeth, or the guide of the deflector element could include rows of parallel flat studs, in the shape of teeth, positioned opposite the distribution device.

[0088] The presence of several rows of teeth (or several rows of parallel flat studs) can also influence the guidance of the fluid flow entering the intermediate part 6 of the SRU unit, if the diffuser is positioned upstream of the intermediate part, or influence the guidance of the flow towards the outlet 7 if the diffuser is positioned downstream of the intermediate part.

[0089] The teeth 82 of the comb could also be oriented along an inclined direction DI with respect to an axial direction D of the unit.

[0090] On [Fig.4], we can consider a second row of teeth 82 which are oriented along an inclined direction DI with respect to the axial direction D, the latter being defined here as being parallel to a median direction of cell 4.

[0091] To produce the teeth 82, the distribution device 9 (in general) and all the raised or recessed elements of the deflector element 90, the interconnector plates can be stamped or forged.

[0092] These recessed and raised elements can also be attached and fixed to the plate of an interconnector, according to an alternative embodiment. This latter embodiment may offer an advantage for equipping existing plates of the diffuser according to the invention.

[0093] It is understood from the foregoing how the invention makes it possible to achieve the technical objectives of controlling the distribution and direction of the fluid flow after its entry into a unit (SRU) or before its exit from the unit, so as to distribute the flow in a controlled and uniform manner.

[0094] Of course, the invention is not limited to the examples just described.

Claims

Demands

1. A cell stacking unit (SRU) for an SOEC or SOFC type electrochemical device, said unit comprising at least two interconnector plates (3) between which at least one fluid flows, and comprising: - an inlet (5) through which the fluid is injected into said unit, said inlet (5) having an inlet section (SI), - an intermediate part (6) comprising a cell (4) and in which the fluid is in contact with said cell (4), said intermediate part (6) having a cross-section (S2) of the intermediate part which is larger than the inlet section (SI), and - an outlet (7) through which the fluid is discharged, said outlet (7) having a fluid outlet section (SI), said unit being characterized in that it comprises at least one fluid diffuser (8), positioned between said inlet (5) and said intermediate part (6), and / or between the intermediate part (6) and the outlet (7),the fluid diffuser (8) comprising at least one distribution device (9) positioned upstream of the cell (4) and / or downstream of the cell (4), and ensuring either the distribution of the fluid or the collection of the fluid over the entire length (L) of the section (S2) of the intermediate part (6).

2. Unit according to claim 1, characterized in that it comprises at least two diffusers (8), each positioned respectively upstream of the intermediate part (6) and downstream of the intermediate part (6).

3. Unit according to claim 1 or 2, characterized in that said diffuser distribution device comprises a comb (81) comprising teeth (82) parallel to each other and extending over the entire length (L) of the section (S2) of the intermediate part (6), the orientation of the teeth (82) ensuring in particular a direction of fluid flow through channels (83) towards said cell (4).

4. Unit according to claim 3, characterized in that the comb (81) has teeth (82) of different thicknesses, the thickness of the teeth (82) increasing between a first end (El) of section (S2) and a second end (E2) of section (S2), the difference in thicknesses defining channels (83) of different widths.

5. Unit according to claim 4, characterized in that the width of the channels (83) increases between said first end (El) and said second end (E2), ensuring a more difficult passage of the fluid at said first end (El) than at said second end (E2).

6. Unit according to any one of claims 3 to 5, characterized in that said teeth (82) of the comb (81) are oriented along an inclined direction (Dl) with respect to an axial direction (D) of the unit, said axial direction of the unit being parallel to a median direction of the cell.

7. Unit according to any one of the preceding claims, characterized in that said fluid diffuser (8) further comprises at least one deflector element (90) upstream of the distribution device (9), ensuring the orientation of the fluid from the inlet (5) of the unit towards the intermediate part (6) and towards said distribution device (9), along a direction or along a bundle of predetermined directions over the entire section (S2) of the intermediate part (6).

8. Unit according to claim 7, characterized in that said deflector element (90) comprises a guide of variable section, which extends between the inlet (5) of the unit and said intermediate part (6), said variable section enlarging between the inlet (5) of the unit and the section of the intermediate part (6) upstream of the distribution device (9).

9. Unit according to claim 7, characterized in that said deflector element (90) comprises a guide of variable section, which extends between said intermediate part (6) and the outlet (7), said variable section narrowing between the intermediate part (6) and the outlet (7), downstream of the distribution device (9).

10. Unit according to any one of claims 7 to 9, characterized in that said deflector element (8) has protruding studs (91, 92, 93) which extend between the two interconnector plates.

11. Unit according to claim 10, characterized in that the protruding studs (91) are of round section.

12. Unit according to claim 10, characterized in that the protruding studs (92) have a petal-shaped cross-section.

13. Unit according to any one of claims 10, 11, or 12, characterized in that the studs (92, 93) are positioned in the vicinity of the inlet (5) of the unit.

14. Unit according to any one of claims 11 to 112, characterized in that the studs (91) are uniformly distributed in said deflector element.

15. Unit according to any one of the preceding claims, characterized in that the distribution device (9) and optionally the deflector element (90) of the diffuser device (8) is / are made by stamping an interconnector plate (3).

16. Unit according to any one of claims 1 to 14, characterized in that the distribution device (9) and optionally the deflector element (90) of the diffuser device (8) is / are made independently of the interconnector plates (3) and in that it is / are attached and fixed to an interconnector plate (3).

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