EP4567155A1 - Sealing of an electrolysis stack - Google Patents

Abstract

Electrolysis stack (1) comprising a plurality of electrolysis cells (2), each comprising an anode chamber (4) with an anode (6), a cathode chamber (5) with a cathode (7) and a diaphragm (8), wherein the electrolysis stack (1) further comprises a line (9) which passes through at least the diaphragms (8) and which has a respective anode-side connection (10) to the anode chambers (4) and/or a respective cathode-side connection (11) to the cathode chambers (5), wherein the line (9) is composed of a plurality of segments (12), wherein the segments (12) are each formed circumferentially around an interior space (13) of the line (9), wherein the segments (12) are each formed by a first part (14) and a second part (15), wherein between the first part (14) and the second part (15) in each case one of the diaphragms (8) and a contacting therewith and the interior (13) of the line (9) is held by an elastic element (16).

Description

The invention relates to an electrolysis stack with multiple electrolysis cells. Furthermore, the invention relates to the use of such an electrolysis stack.

Electrolysis of water, for example, is usually carried out on an industrial scale using so-called electrolysis stacks. These consist of a large number of electrolysis cells arranged in series. Pipes are often provided for the supply of the electrolyte and for the discharge of the electrolysis products, which are routed through the diaphragms of the electrolysis cell. However, with conventional solutions of this type, sealing these pipes is difficult. This is particularly true with regard to the thermal expansion to which electrolysis stacks are often exposed during operation. Thermal expansion is often a problem because, for example, plastic and steel expand at significantly different rates.

Reliable sealing is important because otherwise, the electrolysis products may mix with each other. For example, if hydrogen and oxygen, the electrolysis products of water electrolysis, mix, this can result in an explosive mixture.

An electrolysis stack can contain several hundred or even over a thousand seals. If one of them fails, it can be difficult to locate and replace it. This is precisely why reliable sealing is so important.

State-of-the-art solutions, in particular, involve the use of asbestos diaphragms. These diaphragms can be as thick as 3 mm, for example. The use of asbestos makes these diaphragms highly compressible. This allows sealing to be achieved simply by pressing pipe sections onto the diaphragms. However, the use of asbestos is no longer desirable or even permitted. A comparable construction is not readily possible with alternative diaphragm materials available.

The object of the present invention is to provide a simple and reliable method for sealing lines in an electrolysis stack compared to the prior art. In particular, asbestos should be avoided.

These objects are achieved with the electrolysis stack and its use according to the independent claims. Further advantageous embodiments are specified in the dependent claims. The features presented in the claims and in the description can be combined with one another in any technologically expedient manner.

According to the invention, an electrolysis stack is presented. The electrolysis stack comprises a plurality of electrolysis cells which are lined up along an axis and held adjacent to one another, wherein the electrolysis cells each comprise an anode compartment with an anode, a cathode compartment with a cathode, and a diaphragm arranged between the anode compartment and the cathode compartment. The electrolysis stack further comprises a line which passes through at least the diaphragms and which has a respective anode-side connection to the anode compartments and/or a respective cathode-side connection to the cathode compartments. The line is composed of a plurality of segments, wherein the segments are each formed circumferentially around an interior of the line, wherein the segments are each formed by a first part and a second part, wherein one of the diaphragms and an elastic element adjacent thereto and formed circumferentially around the interior of the line are held between the first part and the second part.

The electrolysis stack described is preferably configured for water electrolysis. Hydrogen and oxygen can be obtained as electrolysis products through water electrolysis. The electrolyte can be pure water or a water-containing mixture. In particular, it is preferred that the electrolysis stack be configured for alkaline electrolysis. However, the advantages described herein can be achieved regardless of which electrolyte is used and which electrolysis products are obtained. The electrolysis stack is preferably configured for high-pressure electrolysis. This is understood to mean electrolysis with an operating pressure of at least 10 bar. The sealing advantages described below are particularly relevant in this context.

The electrolysis stack comprises several electrolysis cells. In each of the electrolysis cells, electrolysis can be carried out independently of the other electrolysis cells. In order to obtain the electrolysis products on a large scale, several electrolysis cells are provided. The electrolysis cells are arranged in a row along an axis, adjacent to one another. The electrolysis cells are preferably pressed together. This can be achieved, for example, using tension rods. These are rods arranged parallel to the electrolysis cells, via which a force is exerted on the electrolysis cells.

The electrolysis cells each comprise an anode compartment with an anode, a cathode compartment with a cathode, and a diaphragm arranged between the anode compartment and the cathode compartment. The anodes can be arranged within the respective anode compartment or at the edge of the respective anode compartment. The cathodes can be arranged within the respective cathode compartment or at the edge of the respective cathode compartment. The anodes and cathodes can each be composed of a single piece of metal or of several parts. For example, the cathodes can each be formed by a plate and a supporting fabric made of wire attached to it. The plate can be very thin and very soft. The supporting fabric can hold the plate in shape. In general, however, the design of the anode compartments, anodes, cathode compartments, and cathodes is irrelevant for the idea described herein. In particular, any design of anode compartments, anodes, cathode compartments, and cathodes known from the prior art can also be used.

The anode chambers and/or the cathode chambers are preferably each designed to withstand a pressure of at least 10 bar. The diaphragms are preferably asbestos-free.

The electrolysis stack further comprises a line which passes through at least the diaphragms and which has a respective anode-side connection to the anode compartments and/or a respective cathode-side connection to the cathode compartments. In addition to the diaphragms, the line can also pass through other elements, in particular the anodes and the cathodes. If bipolar plates are used, The line also passes through the bipolar plates. If the anodes and/or cathodes are each composed of multiple parts, the line can pass through one or more of these parts. It can be useful for practical reasons for the line to pass through other elements in addition to the diaphragms. However, for the idea described here, it is sufficient for the line to pass through the diaphragms.

If the line has the anode-side connections but not the cathode-side connections, the electrolysis stack is preferably configured to supply an anolyte to the anode compartments via the line or to discharge anode-side electrolysis products from the anode compartments. In the first case, the line can be referred to as an anode-side supply line and in the second case as an anode-side discharge line.

If the line has the cathode-side connections but not the anode-side connections, the electrolysis stack is preferably configured to supply a catholyte to the cathode compartments via the line or to discharge cathode-side electrolysis products from the cathode compartments. In the first case, the line can be referred to as a cathode-side supply line and in the second case as a cathode-side discharge line.

If the line has both the anode-side connections and the cathode-side connections, the electrolysis stack is preferably configured to supply an electrolyte to the anode compartments and the cathode compartments via the line. In this case, the line can be referred to as a supply line.

The advantages described herein can be achieved for all the previously described supply and discharge lines. It is therefore sufficient for the electrolysis stack to have one line configured as described in order to achieve the advantages according to the invention. It is irrelevant whether this line is a supply line or a discharge line. It is also irrelevant whether this line is connected only to the anode compartments, only to the cathode compartments, or to both the anode compartments and the cathode compartments. However, it is preferred that the electrolysis stack have a plurality of lines configured as described. This is particularly the case in the following embodiments.

In a first embodiment, the electrolysis stack has an anode-side supply line, an anode-side discharge line, a cathode-side supply line, and a cathode-side discharge line. The anode-side supply line has a respective anode-side connection to the anode compartments. The anode-side discharge line has a respective anode-side connection to the anode compartments. The cathode-side supply line has a respective cathode-side connection to the cathode compartments. The cathode-side discharge line has a respective cathode-side connection to the cathode compartments. The electrolysis stack is configured to supply an anolyte to the anode compartments via the anode-side supply line, discharge anode-side electrolysis products from the anode compartments via the anode-side discharge line, supply a catholyte to the cathode compartments via the cathode-side supply line, and discharge cathode-side electrolysis products from the cathode compartments via the cathode-side discharge line.

In a second embodiment, the electrolysis stack has a supply line, an anode-side discharge line, and a cathode-side discharge line. The supply line has a respective anode-side connection to the anode compartments and a respective cathode-side connection to the cathode compartments. The anode-side discharge line has a respective anode-side connection to the anode compartments. The cathode-side discharge line has a respective cathode-side connection to the cathode compartments. The electrolysis stack is configured to supply an electrolyte to the anode compartments and the cathode compartments via the supply line, to discharge anode-side electrolysis products from the anode compartments via the anode-side discharge line, and to discharge cathode-side electrolysis products from the cathode compartments via the cathode-side discharge line.

The description herein for the line applies accordingly to the supply lines and discharge lines described for the first and second embodiments. For the sake of simplicity, the general reference to "the line" will be made below.

The line is composed of several segments. Each segment represents an axial section of the line, whereby adjacent segments can overlap axially. Designing the line with segments can facilitate the manufacture and maintenance of the electrolysis stack. The segments can be firmly connected to one another, but this is not required. The segments can They can also be loosely connected and held together by an external force. This external force can be the same force that holds the electrolysis cells together.

The segments are each designed to encircle an interior space of the pipe. The segments can therefore be considered either pipe sections or pipe segments.

The segments are each formed by a first part and a second part. The first part and the second part are preferably each formed circumferentially around the interior of the conduit.

Dividing the segments into a first and a second part can simplify their manufacture. This division also ensures that the diaphragms are securely held on the line. For this purpose, one of the diaphragms and an elastic element adjacent to the diaphragm and extending around the interior of the line are held between the first and second parts. The diaphragm can be clamped between the two parts. The diaphragm can be held force-fittingly between the two parts, in particular via the elastic element. The elastic element is preferably compressible.

The elastic element can help to hold the diaphragm securely between the two parts. The elastic element can press the diaphragm against the second part. The diaphragm preferably rests against a surface of the second part. The surface is preferably textured. This can help to hold the diaphragm sealed to the surface. Although the elastic element primarily serves to hold the diaphragm securely, the elastic element can also contribute to sealing. The textured design of the surface of the second part supports this. The surface preferably has sealing grooves. This is an example of the described textured design of the surface.

The elastic element is preferably annular. Particularly preferably, the elastic element is formed as an O-ring. The elastic element is preferably made of a plastic. By using the elastic element, the diaphragms do not have to be elastic, as is the case with the asbestos diaphragms known from the prior art.

In the electrolysis stack described, sealing is no longer achieved by pressing line segments onto compressible diaphragms. Instead, it is sufficient for the line segments to be held together. The diaphragms are held in place by the elastic element. The elastic element contributes to the sealing of the line.

In order to achieve the advantages described here, it is not important how many segments the line is composed of. It has proven particularly advantageous if exactly one of the segments is assigned to each of the electrolysis cells. In this case, the line has exactly one segment per electrolysis cell. In this case, the diaphragm of the electrolysis cell assigned to the segment and an elastic element adjacent to the diaphragm and formed around the interior of the line are preferably held between the first part and the second part. If the line has exactly one segment for each of the electrolysis cells, all diaphragms can be held as described above. However, there is nothing to prevent more or fewer segments than electrolysis cells.

If bipolar plates are used, the division of the line into segments can also be used to hold the bipolar plates. Bipolar plates are arranged between adjacent electrolysis cells, each held between two adjacent segments. Preferably, the bipolar plates are held, in particular clamped, between the first part of one of the segments and the second part of the segment following in the axial direction. The fact that the bipolar plates are also held by the line can increase the stability of the electrolysis stack.

In a preferred embodiment of the electrolysis stack, the segments each have a projection extending in the axial direction and a receptacle, wherein the projections each engage in the receptacle of the segment following in the axial direction.

When two adjacent segments are used, the projection of one segment engages the recess of the other segment. This allows the segments to be securely held together. It is sufficient for the projection to be inserted into the recess. A force-locking connection between the projection and recess is not required. The segments can also be loosely placed together and held together by an external force. This external force can be the same force that holds the electrolysis cells together.

The projection is preferably configured to extend circumferentially around the interior of the line. The projection can therefore be annular. The receptacle is preferably configured as a counterpart to the projection of the segment following in the axial direction. This is already implicitly contained in the wording that the projection engages in the receptacle. The receptacle is preferably configured to extend circumferentially around the interior of the line. The receptacle can therefore be configured as an annular recess.

In a further preferred embodiment of the electrolysis stack, the projections each engage in the receptacle of the segment following in the axial direction, sealed by an O-ring.

The line is formed by the adjacent segments. To ensure a tight line seal, it may be sufficient to press the segments together. In the present embodiment, however, O-rings are also provided to seal the line. O-rings between the segments seal the interior of the line from the surroundings of the line—in particular, from the anode and cathode compartments. This seal does not interfere with the described connection of the line to the anode and/or cathode compartments.

The O-ring can be held in a gap between the receptacle and the projection engaging therein. The O-ring is preferably in contact with both the projection and an edge of the receptacle. The O-ring thus bridges the gap and seals it. The O-ring is preferably arranged radially between the edge of the receptacle and the projection engaging the receptacle.

In this embodiment, the O-ring can be used to seal the line, while the elastic element is used to hold the diaphragms. These two functions can therefore be separated. Nevertheless, the elastic element can also contribute to sealing the line.

In a further preferred embodiment of the electrolysis stack, the receptacles each have a recess on a radially inner side which is formed circumferentially around the interior of the line, wherein the O-rings are each partially received in one of the recesses.

In this embodiment, the O-ring is arranged radially between the edge of the receptacle and the projection engaging in the receptacle. This can basically be the case if the O-ring is arranged radially inside the projection or radially outside the projection. In the present embodiment, the O-ring is arranged radially inside the projection. Accordingly, a recess for the O-ring is provided on the radially inner side of the receptacle. The O-ring is partially accommodated in this recess, but not completely. The O-ring therefore protrudes radially outwards beyond the recess. This allows the O-ring to fulfill its function of sealing a gap between the projection and the receptacle. The recess can hold the O-ring in position. This facilitates the manufacture and maintenance of the electrolysis stack.

In a further preferred embodiment of the electrolysis stack, the receptacles and the projections each have a thread, wherein the projections each engage in the receptacle of the segment following in the axial direction by means of the thread while screwing.

The screw connection ensures that the projections are securely held in their respective slots, increasing the stability of the cable.

As an alternative to the present embodiment, the projections can also be held in the corresponding receptacle in a different manner: force-fitting, form-fitting, or both force-fitting and form-fitting. However, the projections can also engage loosely in the receptacles and be held therein by an external force. This external force can be the same force that holds the electrolysis cells together.

In a further preferred embodiment of the electrolysis stack, the segments are each spaced from the segment following in the axial direction by a gap formed outside the projection.

In this embodiment, it is sufficient for the adjacent segments to be in contact with each other by the projection engaging the corresponding receptacle. Furthermore, a gap is formed between the segments. This gap has the advantage of being able to compensate for thermal expansion of the segments. This may even make it possible to dispense with the springs commonly used on the tie rods.

In a further preferred embodiment of the electrolysis stack, the first parts and/or the second parts of the segments are each formed from a polymer. The "and" case is preferred.

It has been found that the use of polymer makes the production of the parts particularly easy.

In a further preferred embodiment of the electrolysis stack, the diaphragms each have a thickness of less than 1 mm.

Preferably, the diaphragms each have a thickness in the range of 0.01 to 0.8 mm.

This embodiment is in particular in contrast to the solutions known from the prior art with diaphragms made of asbestos, which, for example, have a thickness of 3 mm. Instead, the present embodiment provides for the use of diaphragms with a thickness of less than 1 mm, for example with a thickness of 0.5 mm. The diaphragms are preferably incompressible. The diaphragms are preferably asbestos-free. Due to the small thickness, it is not possible to achieve the seal solely through the elasticity of the diaphragms and external pressure, as in the prior art. However, the described design of the segments with the elastic element still achieves a good seal.

Apart from that, the described form of sealing has the advantage over sealing by pressing pipe sections onto the diaphragms that thermal expansion has a lesser influence on the tightness.

In a further preferred embodiment of the electrolysis stack, the diaphragms are held only force-fitting between the elastic element and the second part of the respective segment.

The diaphragms are held between the parts of the respective segment by the elastic element. The elastic element, in particular, contributes to the frictional retention of the diaphragms.

As a further aspect of the invention, a use of an electrolysis stack designed as described for alkaline electrolysis is presented.

The described advantages and features of the electrolysis stack are applicable and transferable to the application, and vice versa. The described electrolysis stack is preferably designed for alkaline electrolysis.

The electrolysis is preferably a high-pressure electrolysis. The electrolysis is preferably operated at an operating pressure of at least 10 bar, for example, at an operating pressure of 30 bar. The described advantages regarding sealing are particularly relevant in connection with such high pressures.

Fig. 1:

einen erfindungsgemäßen Elektrolysestack,

Fig. 2:

eine Detailansicht des Elektrolysestacks aus Fig. 1,

Fig. 3:

eine weitere Detailansicht des Elektrolysestacks aus Fig. 1,

Fig. 4:

ein Segment für eine Leitung, wie es in dem Elektrolysestack aus den Fig. 1 bis 3 verwendet werden kann.

The invention is explained in more detail below with reference to the figures. The figures show a particularly preferred embodiment, to which the invention is not limited, however. The figures and the proportions depicted therein are merely schematic. They show:

Fig. 1:

an electrolysis stack according to the invention,

Fig. 2:

a detailed view of the electrolysis stack Fig. 1 ,

Fig. 3:

another detailed view of the electrolysis stack Fig. 1 ,

Fig. 4:

a segment for a line, as it is in the electrolysis stack from the Fig. 1 to 3 can be used.

Fig. 1 shows an electrolysis stack 1 with four electrolysis cells 2. The electrolysis stack 1 can be used for alkaline water electrolysis. The electrolysis cells 2 are arranged in a row along an axis 3. The electrolysis cells 2 each comprise an anode chamber 4 with an anode 6, a cathode chamber 5 with a cathode 7, and a diaphragm 8 arranged between the anode chamber 4 and the cathode chamber 5. The diaphragms 8 each have a thickness of less than 1 mm. In the illustration of the Fig. 1 The thickness of the diaphragms 8 is the extension of the diaphragms 8 in the right/left direction. The anodes 6 and the cathodes 7 are each arranged close to the intermediate diaphragm 8. The electrolysis cells 2 are connected to one another by bipolar plates 24. At the left and right edges of the electrolysis stack 1, an end plate 25 is provided instead of a bipolar plate 24. The anodes 6 and the cathodes 7 are each electrically connected to one of the bipolar plates 24 or one of the end plates 25. This is indicated schematically by hatched connections.

The electrolysis stack 1 further comprises two lines 9, which pass through the diaphragms 8, the anodes 6 and the cathodes 7, respectively. Fig. 1 The line 9 shown above has a respective anode-side connection 10 to the anode compartments 4. An anolyte can be supplied to the anode compartments 4 via this line 9. Alternatively, a mixture of anode-side reaction products and unused anolyte can be discharged from the anode compartments 4 via this line 9. The Fig. 1 Line 9 shown below has a respective cathode-side connection 11 to the cathode compartments 5. A catholyte can be supplied to the cathode compartments 5 via this line 9. Alternatively, a mixture of cathode-side reaction products and unused catholyte can be discharged from the cathode compartments 5 via this line 9.

The lines 9 are each composed of several segments 12. This is shown in Fig. 1 only indicated schematically by dotted lines. This is shown in more detail in the following figures. Each of the electrolysis cells 2 is assigned one of the segments 12. The segments 12 are each formed circumferentially around an interior space 13 of the line 9.

Fig. 2 shows a section of the electrolysis stack 1 from Fig. 1 . One of the lines 9 can be seen. The representation of the Fig. 2 applies to both Fig. 1 marked lines 9.

Openings can be seen distributed around the circumference of the line 9, which represent the anode-side connections 10 and the cathode-side connections 11, respectively. Three of the segments 12 are shown. These are shown in more detail in the following figures.

Fig. 3 shows an excerpt from Fig. 2 . Here, too, three of the segments 12 are shown, some of them, but not in full. The segments 12 are each formed by a first part 14 and a second part 15 made of a polymer. Between the first part 14 and the second part 15, the diaphragm 8 of the electrolysis cell 2 assigned to the segment 12 and an elastic element 16 adjacent to the diaphragm 8 and formed to encircle the interior 13 of the line 9 are held. The diaphragms 8 are held merely in a force-fitting manner between the elastic element 16 and the second part 15 of the segment 12 assigned to the respective electrolysis cell 1.

The segments 12 each have a section extending in the axial direction (in the example of the Fig. 3 to the left) and a receptacle 18. The projections 17 each engage, sealed by an O-ring 19, in the receptacle 18 of the segment 12 following in the axial direction. For this purpose, the receptacles 18 each have a recess 21 on a radially inner side 20 that extends around the interior 13 of the line 9. The O-rings 19 are each partially received in one of the recesses 21.

The receptacles 18 and the projections 17 each have a thread 22. The projections 17 each engage, by means of the thread 22, into the receptacle 18 of the segment 12 following in the axial direction.

The segments 12 are each spaced apart from the segment 12 following in the axial direction by a gap 23 formed outside the projection 17.

Furthermore, Fig. 3 It can be seen that the bipolar plates 24 are held between the segments 12. For this purpose, the bipolar plates 24 are each held between the first part 14 of one of the segments 12 and the second part 15 of the segment 12 following in the axial direction.

Fig. 4 shows a segment 12 for a line 9, as it is in the electrolysis stack 1 from the Fig. 1 to 3 can be used. The first part 14, the second part 15, the elastic element 16 and the O-ring 19 can be seen in particular.

List of reference symbols

1

Electrolysis stack

2

Electrolysis cell

3

axis

4

Anode compartment

5

Cathode compartment

6

anode

7

cathode

8

diaphragm

9

Line

10

anode-side connection

11

cathode-side connection

12

segment

13

Interior

14

first part

15

second part

16

elastic element

17

projection

18

Recording

19

O-ring

20

radially inner side

21

recess

22

thread

23

gap

24

Bipolar plate

25

End plate

Claims (9)

1. Electrolysis stack (1) comprising a plurality of electrolysis cells (2) which are arranged in a row along an axis (3) and are held adjacent to one another, wherein the electrolysis cells (2) each comprise an anode chamber (4) with an anode (6), a cathode chamber (5) with a cathode (7) and a diaphragm (8) arranged between the anode chamber (4) and the cathode chamber (5), wherein the electrolysis stack (1) further comprises a line (9) which passes through at least the diaphragms (8) and which has a respective anode-side connection (10) to the anode chambers (4) and/or a respective cathode-side connection (11) to the cathode chambers (5), wherein the line (9) is composed of a plurality of segments (12), wherein the segments (12) are each formed circumferentially around an interior space (13) of the line (9), wherein the segments (12) are each formed by a first part (14) and a second part (15) are formed, wherein between the first part (14) and the second part (15) one of the diaphragms (8) and an elastic element (16) adjacent thereto and formed to encircle the interior (13) of the line (9) are held. 2. Electrolysis stack (1) according to claim 1, wherein the segments (12) each have a projection (17) extending in the axial direction and a receptacle (18), and wherein the projections (17) each engage in the receptacle (18) of the segment (12) following in the axial direction. 3. The electrolysis stack (1) according to claim 2, wherein the projections (17) each engage in the receptacle (18) of the axially following segment (12) while being sealed by an O-ring (19). 3. The electrolysis stack (1) according to claim 2, wherein the receptacles (18) each have, on a radially inner side (20), a recess (21) circumferentially formed around the interior space (13) of the line (9), and wherein the O-rings (19) are each partially received in one of the recesses (21). 4. Electrolysis stack (1) according to claim 2 or 3, wherein the receptacles (18) and the projections (17) each have a thread (22), and wherein the projections (17) each engage in the receptacle (18) of the segment (12) following in the axial direction by means of the thread (22). 5. Electrolysis stack (1) according to one of claims 2 to 4, wherein the segments (12) are each spaced from the segment (12) following in the axial direction by a gap (23) formed outside the projection (17). 6. Electrolysis stack (1) according to one of the preceding claims, wherein the first parts (14) and/or the second parts (15) of the segments (12) are each formed from a polymer. 7. Electrolysis stack (1) according to one of the preceding claims, wherein the diaphragms (8) each have a thickness of less than 1 mm. 8. Electrolysis stack (1) according to one of the preceding claims, wherein the diaphragms (8) are held only in a force-fitting manner between the elastic element (16) and the second part (15) of the respective segment (12). 9. Use of an electrolysis stack (1) according to one of the preceding claims for alkaline electrolysis.

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