WO2023247549A1

WO2023247549A1 - Elektrolyser, use for an elektrolyser, supply pipe for an electrolyser and discharge pipe for an electrolyser

Info

Publication number: WO2023247549A1
Application number: PCT/EP2023/066656
Authority: WO
Inventors: Dirk Diehl
Original assignee: Siemens Energy Global GmbH & Co. KG
Priority date: 2022-06-22
Filing date: 2023-06-20
Publication date: 2023-12-28
Also published as: DE102022206228A1

Abstract

The invention relates to an electrolyser (2) comprising a plurality of cell elements (4) and comprising a supply pipe (6) and a discharge pipe (8) for supplying and discharging an electrolyte to and from the cell elements (4), wherein, at least in sections, the supply pipe (6) and/or the discharge pipe (8) have at least two sub-lines (12a to 12t) that are galvanically isolated from one another, wherein the sub-lines (12a-12t) are designed an eccentric sub-lines (12a-12t).

Description

Electrolyzer, insert for an electrolyzer, supply pipe for an electrolyzer and discharge pipe for an electrolyzer

The invention relates to an electrolyzer with a plurality of cell elements and with a supply pipe and a discharge pipe for supplying and discharging electrolyte to and away from the cell elements. The invention further relates to an insert for such an electrolyzer, a supply pipe for such an electrolyzer and a discharge pipe for such an electrolyzer.

During electrolysis, redox reactions that are associated with material conversions can be enforced by imposing an electric current through suitable cell elements. A device for this purpose is called an electrolyzer and can be used to produce important raw materials in the chemical industry. In many cases, anode and cathode halves are separated by diaphragms (or membranes), which enable electrical conductivity (ion and/or proton exchange) but prevent material exchange. If liquid electrolytes are used in electrolysers, which are changed or are consumed, they can be continuously renewed during the process using appropriate supply and discharge lines. The substance conversion rates for given cell elements are generally subject to narrow limits due to current density limitations. For large-scale use, the active cell element area must therefore be increased in order to increase the material conversion rates. This can be achieved by increasing the size of the cell elements or by operating a plurality of smaller cell elements at the same time. A technically sensible and frequently used method is to arrange many (same) cell elements into a stack. The electrical connection of the cell elements of a stack provides represents a series connection, ie the anode of a cell element N is connected to the cathode of the cell element N+l and the cathode of the cell element N is electrically conductively connected to the anode of the cell element Nl. The series connection also multiplies the low cell element voltage from a few volts to, for example, several hundred volts. The hydraulic connection of the cell elements of a stack to supply fresh electrolytes, however, represents a parallel connection. The hydraulic connection of the cell elements to form a stack creates additional and undesirable electrically conductive connections between all cell elements. When operating the stack of cell elements, ie applying an electrical voltage or impressing an electrical current from the first to the last cell element, an electrical working current flows through all cell elements. However, unwanted so-called electrical stray currents also flow on the various parallel current paths. These electrical stray currents lead to local current density increases close to the supply lines and discharge lines of the electrolytes, particularly on the first and last cell elements of a stack. This can lead to premature aging and destruction of the membranes and failure of the entire stack.

A reduction in electrical stray currents can be achieved by increasing the electrical resistance of the electrolyte supply and discharge lines. The previous solution envisages extending the supply lines and outgoing lines, which results in an increase in resistance while maintaining the same cross-sectional area. However, the line extensions disadvantageously lead to increased flow resistance and increased material requirements for production.

There is therefore a need to show ways in which this can be remedied. The object of the invention is achieved by an electrolyzer, with a plurality of cell elements, and with a supply pipe and a discharge pipe for supplying and discharging electrolyte to and away from the cell elements, the supply pipe and / or the discharge pipe being at least two galvanically separated from one another at least in sections has separately formed partial lines, wherein the partial lines are designed as eccentric partial lines and are set up in such a way that a current path extension of the current paths is caused by electrical stray currents in the supply pipe and / or the discharge pipe.

A supply pipe or discharge pipe is understood to mean an elongated hollow body whose length is significantly larger than its diameter. In contrast to a hose, a pipe is made of relatively inflexible material. The supply pipe and the discharge pipe can be designed to be so rigid that manual deformation, as with a hose, such as a corrugated hose, is impossible, but the use of tools is required.

In other words, the plurality of cell elements that form a stack are divided into at least two cell element groups that are electrically better insulated from one another by means of the at least two partial lines that are designed to be galvanically isolated from one another. In this way, a current path extension is achieved for at least part of the electrical stray currents, which result in a higher ohmic resistance due to the extension, without the supply pipe and/or discharge pipe being lengthened, which in turn would result in increased flow losses.

The fact that the partial lines are designed as eccentric running partial lines results in a particularly stable structure with optimized utilization of the cross-sectional area of the Supply pipe or drain pipe possible. The term eccentric is understood to mean outside a circle center or pivot point, for example arrangements in which the partial lines are not arranged in relation to one another like concentric circles or rings.

According to one embodiment, at least one of the partial lines is designed to form a honeycomb structure. The partial lines with their respective cross-sectional areas thus form a regular pattern with the cross-sectional areas as cell elements. The respective cross-sectional areas can have any basic shape, for example triangular, square, or even circular. Such a honeycomb structure leads to a particularly stable structure without additional stabilizing elements.

According to a further embodiment, at least one of the partial lines has a hexagonal cross-sectional area.

The respective cross-sectional areas thus form a honeycomb structure, which is at the same time particularly stable and provides maximized cross-sectional areas.

According to a further embodiment, the partial lines are each designed to provide the same cross-sectional area. This ensures that each cell element group can be supplied with the same amount of electrolyte per unit of time. This makes a particularly simple structure possible, since each of the cell element groups can have the same number of cell elements.

According to a further embodiment, the partial lines in the supply pipe extend with a predetermined length in the direction opposite to the electrolyte flow direction and/or in the discharge pipe with a predetermined length in the direction of the electrolyte flow direction. In this way, the current path extension can be increased again. According to a further embodiment, at least one of the partial lines is formed by a passage which extends through an insert in the supply pipe and/or discharge pipe. The partial lines can therefore be formed particularly easily by a one-piece and/or component made of the same material.

According to a further embodiment, at least one of the partial lines is formed by a groove which extends parallel to the passage. In other words, while the other partial lines are completely covered by the insert, the partial line formed by the groove is only partially covered by the insert. Rather, the insert and the pipe jacket of the supply pipe or discharge pipe together form a casing for this passage. In this way, another partial line can be formed particularly easily.

According to a further embodiment, the insert has at least one pipe section and a ring element assigned to each pipe section, the respective ring element extending radially outwards from the pipe section and ending at least one partial line. For example, the insert can be designed in one piece and/or with the same material and thus enables the plurality of partial lines to be formed by assembling just one component.

The invention also includes an insert for such an electrolyzer, a supply pipe and a discharge pipe for such an electrolyzer.

The invention will now be explained using a drawing. Show it:

Figure 1 shows a schematic representation of components of an electrolyzer. Figure 2 shows a schematic representation of an insert for the electrolyzer shown in Figure 1.

Figure 3 shows a schematic representation of further details of the insert shown in Figure 2.

Figure 4 shows a schematic representation of further details of the insert shown in Figure 2.

Figure 5 shows a schematic representation of further details of the insert shown in Figure 2.

Figure 6 shows a schematic representation of further details of the insert shown in Figure 2.

Figure 7 is a schematic representation of a further representation of the electrolyser shown in Figure 1 with an insert shown in Figures 2 to 7.

Reference is first made to FIG. 1.

An electrolyzer 2 is shown.

In the present exemplary embodiment, the electrolyzer 2 has a plurality of cell elements 4, which form a stack 10 and are electrically connected in series. Furthermore, the electrolyzer 2 in the present exemplary embodiment has a supply pipe 6 and a discharge pipe 8, each with circular cross-sectional areas, with which electrolyte can first be supplied to the cell elements 4 and then removed from the cell elements 4. For this purpose, both the supply pipe 6 and the discharge pipe 8 each have a plurality of outlet and inlet openings (not shown).

In order to extend the current path of electrical stray currents, the following exemplary embodiments are An insert 14 is inserted into the supply pipe 6 and the discharge pipe 8.

The structure of an exemplary embodiment of the insert 14 will now be explained with additional reference to FIGS. 2 to 6.

In the present exemplary embodiment, the insert 14 has 19 pipe sections 16a to 16s, each of which forms a partial line 12a to 12s. Deviating from the present exemplary embodiment, the number of pipe sections 16a to 16s can also be different.

Furthermore, in the present exemplary embodiment, each of the partial lines 12a to 12s each have a hexagonal cross-sectional area and thus form a honeycomb structure or honeycomb structure. In other words, in the present exemplary embodiment, the partial lines 12a to 12s are each formed by a passage 20a to 20s, which extend through the insert 14 along their main extension direction and in the present exemplary embodiment are each formed in a straight line and parallel to one another.

The passages 20a to 20s or the webs connecting the passages 20a to 20s can form flow-optimized inlet areas through rounding.

A homogenization of the electrolyte distribution can be achieved through optimized cross-sectional areas of the supply and discharge lines of the respective cell element of the stack 10, accompanied by an adjustment of the flow resistance, i.e. deviations from the uniform honeycomb structure and/or through optimized inlet surfaces.

Furthermore, the partial lines 12a to 12s are designed as eccentric running partial lines 12a to 12s, that is, they are located outside a circle center or rotation. point. In other words, the partial lines 12a to 12s are not arranged relative to one another like concentric circles or rings in the present exemplary embodiment.

In the present exemplary embodiment, one of the partial lines 12t is further formed by a groove 22 which extends parallel to the passages 20a to 20s and forms a further passage 20t.

The partial line 12t formed by the groove 22 is only partially covered by the insert 14. Rather, the insert 14 and the pipe jacket of the supply pipe 6 or discharge pipe 8 together form a casing of this passage 20t.

Each of the partial lines 12a to 12t ends at a ring element 18a to 18t, which seals the respective partial line 12a to 12t from the supply line 6 or discharge line 8. Thus, with each of the sub-lines 12a to 12t, a cell element group of the stack 10 can be supplied with electrolyte or electrolyte can be disposed of. In the present exemplary embodiment, a first cell element group is supplied with electrolyte in the electrolyte flow direction E through the partial lines 12t formed by the groove 22 or electrolyte is disposed of.

In the present exemplary embodiment, the insert 14 is designed in one piece and/or using the same material. In particular, in the present exemplary embodiment, the insert 14 - as well as the supply pipe 6 and the instructions 8 - are made of an electrically insulating material.

Reference will now also be made to FIG. 7.

It is shown that when inserted into the supply pipe 6 or discharge pipe 8, the respective ring elements 18a to 18t come into contact with the inner wall of the supply pipe 6 or the discharge pipe 8 and thus conclude provides, which in the present exemplary embodiment closes one of the sub-lines 12a to 12t, where additional seals can be provided for sealing purposes. Small leaks of the insert 14 between adjacent cell element groups of the stack can be tolerated, resulting in a simple sealing concept.

In the present exemplary embodiment, the supply pipe 6 and the discharge line 8 are designed to be rigid in the section in which the respective inserts 14 are located and are flexible in comparison in the remaining section.

In the present exemplary embodiment, the respective cross-sectional areas of the partial lines 12a to 12t are the same size. In this way, a largely homogeneous electrolyte distribution across all cell element groups of the stack 10 can be achieved.

For example, a stack 10 with 20 cell elements is supplied with electrolyte.

Furthermore, in the present exemplary embodiment, the inserts 14 inserted into the supply pipe 6 and the discharge pipe 8 extend in the case of the supply pipe 6 with a predetermined length L in the direction opposite to the electrolyte flow direction E and in the case of the discharge pipe 8 with the predetermined length L in the direction Electrolyte flow direction E. In the present exemplary embodiment, the respective lengths L are the same size. However, in deviation from the present exemplary embodiment, they can also be of different sizes.

In the present exemplary embodiment, the length L has a value in the range from 0.5 m to 3 m, for example 2 m.

Inserting the insert 14 separates the individual sections of the stack 10. This eliminates stray electrical currents that emerge from the rear sections and into the front ones Sections are forced to enter extended current paths S. The extended current paths S are connected to an increased ohmic resistance, which reduces the electrical stray current strengths. In this way, a maximum of the electrical stray current density can be reduced by 70% (to 30%).

In other words, an electrical series connection and at the same time a hydraulic parallel connection are provided with a particularly compact design.

In this way, a current path extension is achieved for at least part of the electrical stray currents, which results in a higher ohmic resistance due to the extension, without the supply pipe 6 and/or discharge pipe 8 being lengthened, which in turn would result in increased flow losses. At the same time, an insert 14 that is easy to manufacture and particularly stable due to the honeycomb structure is provided.

Claims

Patent claims

1. Electrolyzer (2), with a plurality of cell elements (4), and with a supply pipe (6) and a discharge pipe (8) for supplying and discharging electrolyte to and away from the cell elements (4), the supply pipe (6 ) and/or the discharge pipe (8) has, at least in sections, at least two partial lines (12a to 12t) that are galvanically separated from one another, the partial lines (12a to 12t) being designed as eccentric partial lines (12a to 12t) and being set up in such a way that a current path extension the current paths are caused by electrical stray currents in the supply pipe (6) and/or the discharge pipe (8).

2. Electrolyzer (2) according to claim 1, wherein at least one of the partial lines (12a to 12t) is designed to form a honeycomb structure.

3. Electrolyzer (2) according to claim 2, wherein at least one of the partial lines (12a to 12t) has a hexagon-shaped cross-sectional area.

4. Electrolyzer (2) according to claim 1, 2 or 3, wherein the partial lines (12a to 12t) are each designed to provide the same cross-sectional area.

5. Electrolyzer (2) according to one of claims 1 to 4, wherein the partial lines (12a to 12t) are in the supply pipe (6) with a predetermined length (L) in the direction opposite to the electrolyte flow direction (E) and / or in the Extend discharge pipe (8) with a predetermined length (L) in the direction of the electrolyte flow direction (E).

6. Electrolyser (2) according to one of claims 1 to 5, wherein at least one of the partial lines (12a to 12s) is formed by a passage (20a to 20s) which is through a Insert (14) extends in the supply pipe (6) and/or discharge pipe (8).

7. Electrolyser (2) according to claim 6, wherein at least one of the partial lines (12t) is formed by a groove (22) which extends parallel to the passage (20a to 20s).

8. Electrolyzer (2) according to one of claims 1 to 4, wherein the insert has at least one pipe section (16a, to 16t) and a ring element (18a, to 18t) assigned to each pipe section (16a, to 16t), the respective Ring element (18a, to 18t) extends radially outwards from the respective pipe section (16a, to 16t) and each ends a partial line (12a to 12t).

9. Insert (14) for an electrolyzer (2) according to one of the

Claims 1 to 8.

10. Supply pipe (6) for an electrolyzer (2) with a

Insert (14) according to claim 9.

11. Discharge pipe (8) for an electrolyzer (2) with a

Insert (14) according to claim 9.