Electrolytic cell

Abstract

The present invention relates to a cell stack type electrolytic cell comprising first and second end plates having a plurality of cells axially stapled between the cell stack, a manifold for electrolyte flow from an electrolyte inlet of one of the end plates comprising a plurality of redirecting sections for redirecting the primarily axial electrolyte flow into a primarily radial plane of electrolyte flow, and a bypass at one of the redirecting sections for directing the electrolyte flow around another of the redirecting sections that is axially closer to the electrolyte inlet than the one of the redirecting sections.

Description

Technical Field

[0001] The present invention relates to the field of electrolytic cells, and in particular to a first and a second end plate having a cell stack with a plurality of cells stapled axially therebetween, and a manifold for the flow of electrolyte from an electrolyte inlet of one of the end plates, the manifold comprising a plurality of diversion sections for diverting the mainly axial electrolyte flow mainly into a radial plane electrolyte flow, a cell stack type electrolytic cell.

Background Art

[0002] Such an electrolytic layer of the cell stack type is well known in the art and is disclosed, for example, in EP0212240B1 or DE102014010813A1.

[0003] During operation of such an electrolytic cell, when the cell frame is stapled to form the cell stack, an electrolyte, for example a KOH solution, flows through a manifold formed by holes and openings in the manifold or the cell frame, thereby passing through the active area inside the cell.

[0004] However, it has been found that such conventional electrolytic cells may have reduced performance due to the generation of unwanted currents.

[0005] Therefore, the fundamental object of the present invention is to provide an electrolytic cell having a good combination of moderately stable operating conditions and still a sufficiently simple structure and flexibility of use.

Summary of the Invention

[0006] For this purpose, the present invention provides the electrolytic cell introduced first, which is essentially characterized by a bypass (21) that bypasses another of the diversion sections of the diversion section that is closer to the electrolyte inlet than the one of the diversion sections in the axial direction (X) and guides the flow of electrolyte.

[0007] This configuration has been found to cause non-uniform pressure loss in the electrolyte supply throughout the cell, which is a risk of inefficient cooling of processes, particularly near the side opposite to where the electrolyte inlet and outlet are located, and therefore at least partially a cause of adverse effects on the performance efficiency of conventional electrolytic cells. The bypass allows the pressure drop characteristics of the entire cell to become more equilibrium or homogeneous, enabling better performance with a certain number of cells, or allowing an increase in the number of cells without degradation compared to conventional electrolytic cells with fewer cells. Furthermore, regarding electrical coupling, in devices / plants with more than two electrolytic cells, there is still the possibility of connecting two electrolytic cells in series with a single rectifier. The bypass forces the flow to skip the bypassed reversal section at each axial position, although it does not have (radial) communication with the bypassed reversal section.

[0008] As will be explained later in the detailed description of the drawing, for the sake of simplification, the division of the cell into half-cells is omitted. Therefore, the following explanation applies separately to the electrolyte flow through the anode half-cell on one side and the cathode half-cell on the other side.

[0009] In other words, the present invention provides a cell stack type electrolytic cell comprising: first and second end plates having a cell stack having a plurality of cells stapled axially between them, and a manifold for the flow of electrolyte from one of the end plates, wherein the cell structure itself comprises a bipolar plate and a membrane or diaphragm and has an active region on the inside, and the cell is further subdivided into half cells having an anode half cell and a cathode half cell, and the manifold is mainly for the flow of electrolyte axially. The cell is characterized by a bypass that primarily redirects the electrolyte flow in the radial plane, guiding the electrolyte flow to an active region of either the anode-side half-cell or the cathode-side half-cell. On the one hand, one of the redirection sections of the anode-side half-cell of the cell bypasses another redirection section of the anode-side half-cell of the cell that is closer to the electrolyte inlet in the axial direction than the aforementioned redirection section, thereby guiding the electrolyte flow. On the other hand, one of the redirection sections of the cathode-side half-cell of the cell bypasses another redirection section of the cathode-side half-cell that is closer to the electrolyte inlet in the axial direction than the aforementioned redirection section, thereby guiding the electrolyte flow.

[0010] In these configurations, the multiple diversion sections include multiple first or anode-side diversion sections and multiple second or cathode-side diversion sections. In the anode-side insertion flow, the flow does not have (radial) communication with each bypassed anode-side diversion section, but is forced to skip the diversion section at each axial position, and the opposite is true on the cathode side.

[0011] When a common channel is used for all types of half-cells, as shown in Figure 1 below, each redirection section is understood to belong to a single cell, and each redirection section belonging to a cell naturally has an anode branch and a cathode branch, and the bypass is such that both the anode branch and cathode branch of the redirection section belonging to a single cell are skipped by the flow in the common channel. This is particularly different from the configuration known, for example, US4,950,370A, where, as can be seen from the aforementioned literature, radial redirections occur successively from the flow in one axial channel, and only cells that are supplied with flow from another channel are skipped.

[0012] In other words, the bypass of the present invention is due to flow through the same axial channel, meaning that the bypassed direction change section and the direction change section into which the flow skipping the bypassed direction change section is directed originate from the same axial flow path. This does not mean that the present invention excludes solutions in which some cells are supplied through one axial channel and other cells are supplied through another axial channel. However, the bypass and skipping according to the present invention should be understood with reference to the same channel.

[0013] Accordingly, the present invention provides an electrolytic cell comprising: first and second end plates having a cell stack having a plurality of cells stapled in the axial direction between them; and a manifold for the flow of electrolyte from an electrolyte inlet of one of the end plates, the manifold comprising a plurality of redirecting sections for redirecting the flow of electrolyte mainly flowing in an axial channel of the manifold to an electrolyte flow mainly in a radial plane, wherein one of the redirecting sections, which is directly connected to the axial channel, has a bypass that directs the flow of electrolyte by bypassing another redirecting section of the redirecting sections which is directly connected to the axial channel and is closer in the axial direction to the electrolyte inlet than the one redirecting section. The term “mainly axial” should be understood in the usual way that the directional component in the direction of extension of the channel in the axial direction is the main directional component, i.e., the axial component is greater than the directional component in the radial plane.

[0014] This reference / attribute to one reversal unit and another (bypassed / skipped) reversal unit to the same channel also applies when there is one separate channel for each group of anode-side half-cells and cathode-side half-cells.

[0015] In a preferred embodiment, all directional reversals are directly connected to a single channel, preferably an axial channel having the same radial and azimuthal positions (where this is the channel for all types of half cells), with all directional reversals belonging to the anode side being directly connected to the same single such channel for the anode-side electrolyte supply, while all directional reversals belonging to the cathode side are directly connected to the same single such channel for the cathode-side half cell electrolyte supply.

[0016] In a preferred embodiment, the length of the flow path from the electrolyte inlet to the other direction change section is longer than the length of the flow path from the electrolyte inlet to the one direction change section. Even without unidirectional flow, a simple channel / passage structure can be used.

[0017] In a more preferred embodiment, more than 20% of the first set of redirecting sections are bypassed, preferably more than 33%. This further increases pressure loss at a distance far axially from the cathode-side endplate. On the other hand, it is preferable that more than 20% of the third set of redirecting sections are not bypassed, preferably more than 25%. This shifts the pressure loss problem to the other end by a limited amount, but the cooling problem is not as severe due to the temperature gradient established in the electrolyte flow during operation. The present invention (thus) relates particularly to partial bypass, i.e., there is no flow in which direct flow access to all cells is in the order of the cell arrangement in the flow direction of a single same flow.

[0018] Preferably more than 20%, and especially more than 33%, of the upstream flow to the second plurality of redirection sections passes through the bypass. The second plurality may coincide with the third plurality. In a fairly simple configuration, the second plurality preferably accounts for less than 67%, and especially less than 60%, of the total cells.

[0019] In a more preferred embodiment, the manifold includes one or more branches that direct the electrolyte flow in both axial directions. This allows for the use of passages for electrolyte flows in different axial directions.

[0020] In a further preferred embodiment, the branching section has essentially radial and / or azimuthal electrolyte flow before branching, i.e., with respect to a projection plane perpendicular to the axial direction of the cell stack, the bypass is shifted radially and / or circumferentially (azimuthal) with respect to channels that extend axially through the cell and where the reversal section is located. In a preferred embodiment, the axial bypass channel and the channel adjacent to the reversal section are displaced azimuthal relative to each other. This allows for a more compact frame structure.

[0021] In a further preferred embodiment, the length of the channel from the electrolyte inlet to the axially furthest directional changeover point is shorter than the length of the channel from the electrolyte inlet to the axially closest directional changeover point. This creates an asymmetric distribution of channel lengths, but to some extent further improves the pressure drop situation.

[0022] In a further preferred embodiment, the electrolytic layer is provided to have axial channels extending through more than 20% of all cells in the cell frame, particularly more than 33%, and more preferably more than 50%, and especially through all cells. The channels connect a plurality of directional changes. It is also conceivable to have more such channels, each connecting a portion of the plurality of directional changes.

[0023] In a more preferred embodiment, the axial position of at least one branch is particularly at least 4%, preferably at least 8%, and particularly at least 12% closer to the other end plate than to the end plate having the electrolyte inlet. This provides a reasonable distribution of flow path lengths.

[0024] In a further preferred embodiment, the difference between the axial flow portion of the total flow path length from the inlet to the outlet between the flow path through the cell furthest axially from the electrolyte inlet and the flow path through the cell closest axially from the inlet, divided by their sum, is less than 20%, preferably less than 12%, and particularly less than 8%. This allows for a more uniform flow path length, particularly with respect to the longest flow path length from the inlet through the cells to the outlet.

[0025] In a further preferred embodiment, it is possible to provide a value where the difference between the axial flow portion of the total flow path length from the electrolyte inlet to the outlet, on the one hand through the cell furthest axially from the electrolyte inlet, and on the other hand through the cell closest axially from the inlet, divided by their sum, is greater than 4%, preferably greater than 8%, and particularly greater than 12%. In particular, the branching and merging sections (corresponding to the reverse branching section on the outlet side) can be provided within only one cell frame.

[0026] In a further preferred embodiment, the electrolytic cell comprises at least 30, preferably at least 50, particularly at least 80 cells. It is also envisaged that it has at least 100 cells, further at least 120 cells, and further at least 140 cells.

[0027] The cell structure itself may preferably have a bipolar plate, an electrode and a membrane or diaphragm within a single frame per cell. In this regard, the structure described in Figure 1A of DE102014010813A1 is incorporated by reference, regardless of the presence of additional reinforcing rings.

[0028] Furthermore, the present invention provides an apparatus or plant comprising at least one rectifier having poles connected to the end plates of the electrolytic cell, two electrolytic cells being connected in series to one of the at least one rectifier, and one or both of the two electrolytic cells being configured according to any of the前述 aspects.

[0029] Furthermore, the present invention also provides a method for performing electrolysis, particularly electrolysis of water, by using one or more electrolytic cells configured according to any of the前述 aspects.

[0030] Further features, details and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief Description of the Drawings

[0031] [Figure 1] Figure 1 schematically shows an electrolytic cell with an electrolyte manifold. [Figure 2] Figure 2 schematically shows an electrolytic cell with another electrolyte manifold. [Figure 3] Figure 3 schematically shows an electrolytic cell with yet another electrolyte manifold. [Figure 4] Figure 4 schematically shows an electrolytic cell with yet another electrolyte manifold. [Figure 5a]Figure 5a shows a cross-section of a cell frame according to one embodiment in the bypass region. [Figure 5b] Figure 5b shows a cross-section of a cell frame according to one embodiment in the bypass region. [Figure 6a] Figure 6a shows a cross-section beyond the bypass region. [Figure 6b] Figure 6b shows a cross-section beyond the bypass region. [Figure 7a] Figure 7a shows a cross-section of the cell frame including the connecting passages. [Figure 7b] Figure 7b shows a cross-section of the cell frame including the connecting passages. [Modes for carrying out the invention]

[0032] As can be seen from Figure 1, the electrolytic cell 100 includes a stack 10 of cells stapled in the axial direction X between the end plates 30 (anode side) and 40 (cathode side, grounded). In the illustrated embodiment, although not recognizable from the axial cross-sectional view, the cells with cell frames are circular when viewed in a projection perpendicular to the axial direction X (Figures 5-7). For the sake of simplicity, the subdivision of the cells into half-cells is omitted. For the specific realization of a cell composed of bipolar plates, it should be understood that the following description applies separately to the electrolyte flow through the anode-side half-cell on one side and the cathode-side half-cell on the other side.

[0033] The cell frame has through-holes that extend axially, and in a stacked configuration, it forms an axially extending channel or passage 20 on the inlet side and another axially extending channel or passage 20 on the outlet side. The electrolyte flows essentially axially through the channel 20 on the inlet side. At the direction change section 25, the electrolyte flow is directed to an active region 27 inside the cell, where the electrolyte flow is essentially in a radial plane perpendicular to the axial direction X. On the outlet side, a (reverse) direction change section 26 directs the electrolyte flow in the radial plane back into essentially axial electrolyte flow.

[0034] Such arrangement of the cell staples 10 as described in the partial explanation in Figure 1 is well known, and conventionally, the inlets 41 and outlets 42 of the end plate 40 are coplanar with the channel 20, and as a result the order of the cells in terms of their axial distance from the cathode-side end plate 40 with the inlets 41 and outlets 42 corresponds to the order of the relevant reversals of direction with respect to their movement toward the electrolyte flow path in the channel 20 from the inlet 41.

[0035] In the embodiment shown in Figure 1, the position of the inlet 41 in the radial plane is displaced relative to its position coplanar with the axial channel 20. Furthermore, additional through-holes are provided in the cell frames of cells closer to the cathode-side end plate 40, forming a second channel or passage 21 in the staple configuration, which extends axially parallel to the channel 20 through multiple cells to approximately half the length of the cells of the cell staple 10 in the embodiment shown in Figure 1. A connecting passage 23 exists in a cell 12 located near the axial center of the cell staple 10, connecting the second axial channel 21 to the (first) axial channel 20. As a result, although the electrolyte flow is guided through the inlet 41 in the cathode-side end plate 40, it enters the axial passage 20 rather axially centered on the cell staple 10.

[0036] From here, the electrolyte flow is directed axially toward the anode end plate 30 on the one hand, and axially reversed toward the cathode end plate 40 relative to the "forward" flow on the other hand. The further flow of electrolyte then passes through the active region 27 of the cell and again through the reversal section 25, and is then collected in the outlet axial channel 20 in this exemplary embodiment. The final outflow of the electrolyte, in the illustrated embodiment, is again displaced radially relative to the (first) passage 20 and enters a second axial passage 22 that is coplanar with the outlet 42 in the cathode end plate 40. In the embodiment shown in Figure 1, the fluid connection between the outlet passages 20 and 22 is made via a connecting passage 23 and a portion 24 substantially opposite in the diametrically opposed direction within the cell frame of the cell 12. However, the connection can also be located in a different axial position.

[0037] In the illustrated embodiment, there is only one connecting passage 23, 24 on both the inlet and outlet sides. However, in other embodiments not shown, there may be more. In such cases, the connecting portions can be narrowed differently from one another to coordinate the correlated flow along all the passages passing through different cells with respect to volumetric flow rate.

[0038] In the embodiment shown in Figure 1, the displacement of the second axial passages 21 and 22 relative to the axial passage 20 is shown as radial displacement. This is one possible solution chosen for illustrative purposes and for illustrative purposes in the figure. However, it may also be configured as circumferential displacement (azimuthal displacement), or as a displacement including radial and azimuthal components, and is more preferable.

[0039] In the embodiment shown in Figure 1, the connecting portion between channels 21, 22, and 20 is located approximately axially centered on the staple 10. However, in other embodiments having an electrolytic cell 101 as shown in Figure 2, an asymmetrical arrangement is possible, where the connecting portions are each shifted away from the cathode side toward the anode side.

[0040] In the embodiment shown in Figure 3, which includes an electrolytic cell 102, there is a "double asymmetrical arrangement" in which the cathode-side connection 23 is shifted relative to the anode side, while the outlet-side connection 24 is shifted relative to the cathode side (the axial center of the staple 10 is the reference for the shift). In the embodiment of Figure 3, the length of the flow path of the cell closest axially to the cathode-side end plate 40 and the length of the flow path of the cell closest axially to the anode-side end plate 30 are essentially equal.

[0041] In the embodiment of Figure 4, which includes the electrolytic cell 103, the bypass is implemented in such a way that the flow splitting is already made outside the end plate. A portion of the cells closer to the inlet side is supplied through the first supply channel, while the other cells are supplied by bypassing the supply of the portion said to be supplied. In addition, in the embodiment of Figure 4, it is possible and preferable to modify the channel (shown as radially displaced) to be displaced in the azimuthal direction.

[0042] Figure 5a shows a cross-section of cell frame 13' corresponding to cell frame 13 in Figure 1, but in the modified embodiment, channel 21 is not radially displaced from channel 20, but is azimuthal, similar to channels 22 and 20 for backflow. Reference numerals 41 and 42 in Figure 5a indicate communication with the respective fluid inlet 41 and fluid outlet 42 in Figure 1. Furthermore, as can be seen from the embodiment in Figure 5a, on the inlet side there are channels 20 and 21 for each of the two groups of half cells, arranged symmetrically with respect to the outlet side where separation is required. However, it is also possible to use only one channel 20 and 21 as a common channel for all types of half cells. This is shown in Figure 5b.

[0043] Figures 6a and 6b correspond to the different embodiments of Figures 5a and 5b, but relate to cell frame 11' located in the same place as cell frame 11 in Figure 1. The black crosses on channels 21 and 22 indicate that there is no fluid passing through the channels. This is because the channels 21 and 22 (see Figure 1) are not continuous to the other end plate and merge with channel 20 at the connecting passage 23. As can be easily seen from Figures 6a and 6b, through-holes for channels 21 and 22 are not necessary and may not be present, but through-holes can be present (even if they are not used), and as a result, cell frames 11' and 13' can be manufactured in the same manner.

[0044] The only cell frame that is manufactured separately (and required) is the one that includes the connecting passage 23(23') between the input channels 20 and 21 and the exit channels 22 and 20, respectively. Cross-sections of these cell frames 12' are shown in Figure 7(a) (symmetrical arrangement) and Figure 7(b) (only one channel 20 on the inlet side), where reference numeral 12' indicates an embodiment with azimuthal displacement between channel 22 and bypass channels 21 and 22, in contrast to the graphical representation of cell 12 in Figure 1, where radial displacement exists (primarily for illustrative purposes, but also as a valid embodiment).

[0045] As can be understood from the above, the details of the connection can be modified based on the above characteristics. The presence of bypass 21 achieves a more favorable and uniform pressure drop condition for the electrolyte flow, leading to improved performance of the electrolytic cell.

[0046] The present invention is not limited to the details shown in the drawings. Rather, the features described above and the features of the subsequent claims may be essential to the present invention, either individually or in combination.

Claims

1. A cell stack type electrolytic cell (100, 101), First (30) and second (40) end plates having a cell stack having multiple cells (18, 13, 12, 11, 19) stapled in the axial direction between them, and A manifold for the flow of electrolyte from one of the end plates (41), comprising a plurality of direction changing sections (25) that primarily change the direction of the electrolyte flow in the axial direction to the electrolyte flow in the radial direction. Equipped with, The manifold includes one or more branching sections (23) that direct the flow of the electrolyte in both axial directions, An electrolytic cell characterized in that one of the direction changing sections (25k) has a bypass (21) that bypasses another direction changing section (25j) of the direction changing sections which is closer to the electrolyte inlet in the axial direction (X) than the one of the direction changing sections, and guides the flow of electrolyte.

2. The electrolytic cell according to claim 1, wherein the length of the flow path from the electrolyte inlet to the other direction changing section is longer than the length of the flow path from the electrolyte inlet to one of the direction changing sections.

3. The electrolytic cell according to claim 1, wherein more than 20% of the plurality of direction-changing sections are bypassed.

4. The electrolytic cell according to claim 1, wherein the electrolyte flows via the bypass to more than 20% of the plurality of direction-changing sections on the upstream side of the direction-changing section.

5. The electrolytic cell according to claim 1, wherein the branching section has essentially radial and / or circumferential electrolyte flow before branching.

6. The electrolytic cell according to claim 1, wherein the length of the flow path from the electrolyte inlet to the direction changing section furthest in the axial direction is shorter than the length of the flow path from the electrolyte inlet to the direction changing section closest in the axial direction.

7. The electrolytic cell according to claim 1, having an axial channel extending more than 20% of the cell frame.

8. The electrolytic cell according to claim 1, wherein the axial position of at least one branch is closer to the other end plate than to the end plate having the electrolyte inlet.

9. The electrolytic cell according to claim 1, wherein the difference between the axial flow portion of the total flow path length from the electrolyte inlet to the outlet, in the flow path passing through the cell furthest axially from the electrolyte inlet, and in the flow path passing through the cell closest axially from the inlet, divided by their sum, is less than 20%.

10. The electrolytic cell according to claim 1, wherein the value obtained by dividing the difference between the axial flow portion of the total flow path length from the electrolyte inlet to the outlet, between the flow path passing through the cell furthest axially from the electrolyte inlet on the one hand and the flow path passing through the cell closest axially from the inlet on the other hand, by the sum of these two values ​​is greater than 4%.

11. The electrolytic cell according to claim 1, comprising at least 30 cells.

12. The electrolytic cell comprises at least one rectifier having electrodes connected to the end plate, An apparatus in which two electrolytic cells are connected in series to one of the at least one rectifier, and one or both of the two electrolytic cells are configured according to any one of claims 1 to 11.

13. A method for performing electrolysis using one or more electrolytic cells according to any one of Claims 1 to 11, characterized in that the flow of electrolyte mainly in the axial direction is redirected to a flow of electrolyte mainly in the radial plane, at least a portion of the flow mainly in the axial direction bypasses the redirection area of ​​the flow redirection toward at least another cell of the electrolytic cell, and the flow of electrolyte is toward one of the redirection areas downstream of the bypassed redirection area.

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