Electrochemical plant

Abstract

The invention relates to an electrochemical plant (1), in particular an electrolysis plant, with several electrically connected stacks (2). According to the invention, the electrically connected stacks (2) comprise at least two stack types (A, B) which differ in that they are polarized in opposite directions, wherein the different stack types (A, B) are arranged alternately in the electrical series connection.

Description

[0001] The present invention relates to an electrochemical system comprising at least two stacks connected electrically in series. The electrochemical system can, in particular, be an electrolysis system.

[0002] The preferred field of application of the invention is the production of hydrogen by electrolysis. State of the art

[0003] The heart of an electrochemical plant, especially an electrolysis plant, is the stack, which comprises a large number of electrochemical cells in a stacked arrangement. The electrochemical reaction takes place in the cells. In the case of hydrogen production through electrolysis, water is split into its components hydrogen and oxygen in the electrochemical cells. Electrolysis cells are classified according to the type of ion transport (H + , OH - , O 2-) - are divided into PEM ("Proton Exchange Membrane"), SOEC ("Solid Oxide Electrolyzer Cell"), alkaline and AEM ("Anion Exchange Membrane") cells.

[0004] In electrochemical plants with more than two stacks, these or some of these stacks are usually connected electrically in series. This enables a sensible design of the connected power electronics, in particular an AC / DC converter and / or a DC / DC converter. The stacks are constructed identically, particularly with regard to polarity, so that the electrical series connection requires an electrical connection in the form of a busbar that runs from the upper end of a first stack to the lower end of a second stack. This arrangement is repeated with each additional stack, requiring a lot of material to form the busbars. The costs are correspondingly high and accessibility of the stacks is difficult.

[0005] The present invention is concerned with optimizing the electrical series connection of multiple stacks in order to save material and costs. Furthermore, the accessibility of the stacks is to be improved.

[0006] To solve this problem, the electrochemical system having the features of claim 1 is proposed. Advantageous developments of the invention can be found in the subclaims. Disclosure of the invention

[0007] The invention proposes an electrochemical system, in particular an electrolysis system, comprising a plurality of stacks electrically connected in series. According to the invention, the stacks electrically connected in series comprise at least two stack types that differ in that they have reversed polarity. The different stack types are arranged alternately in the electrical series circuit.

[0008] The reversed polarity of the stacks simplifies the electrical connection between the stacks. When stacks with different polarities are arranged alternately, the poles of two adjacent stacks are oriented such that a positive pole and a negative pole are located next to each other. This allows the positive and negative poles to be electrically connected very easily using an electrical conductor, particularly a busbar. In this case, the electrical conductor or busbar can be made significantly shorter, saving material and costs.

[0009] Preferably, the electrical series connection of two adjacent stacks is achieved via an electrical conductor, in particular a busbar, which connects the two stacks in the region of an upper end section or in the region of a lower end section. This is possible because the two stacks are reversed in polarity, so that the positive pole of one stack and the negative pole of the other stack are adjacent to each other. The electrical conductor or busbar can therefore be very short.

[0010] Furthermore, an electrical conductor, in particular a busbar, which connects two upper end sections of two adjacent stacks is preferably followed by an electrical conductor or busbar that connects two lower end sections and vice versa. Since two different stack types alternate, the position of the electrical conductor or busbar also changes from top to bottom and vice versa. In this way, both the positive pole and the negative pole of a stack arranged between two further stacks can be easily electrically connected to the corresponding poles of the adjacent stack. A stack arranged between two stacks therefore has an electrical conductor, in particular a busbar, in both an upper end section and a lower end section for electrically connecting to the adjacent stacks.

[0011] The same preferably applies analogously to a stack arranged at the end of an electrical series circuit, since this stack does not need to be connected to another stack, but rather to a power electronics system. This can also be achieved via an electrical conductor, in particular a busbar, so that a terminal stack also has an electrical conductor or busbar in an upper end section and a lower end section.

[0012] According to a preferred embodiment of the invention, the electrical series connection of two adjacent stacks is achieved via a busbar that runs essentially parallel to the cell planes of the two stacks. This allows the length of the busbar to be minimized. This requires that the external dimensions of the stacks are essentially the same. The busbar 3 can be designed, in particular, as a solid metal bar, for example, made of copper, or as a flexible electrical cable.

[0013] Furthermore, it is proposed that the stack types, which differ in terms of polarity, have media connections that are arranged at the same location on the respective stack in the final installation position of the stack. This means that all stacks have the same media connections. This means that the media connections must be arranged on the same side of the stack, thus simplifying and standardizing media routing. In particular, cable lengths can be saved. The media connections can, in particular, be the connections of a stack to a water circuit and the connection for discharging the product gases or gas-liquid mixtures, provided the electrochemical plant is an electrolysis plant.

[0014] Since the media connections of two adjacent stacks are identical, while the electrical polarity is reversed, there is a risk that the different stack types will be connected incorrectly during the assembly of the electrochemical system. This means that two identical stack types are mistakenly electrically connected to each other. This must be prevented. Furthermore, it is important to prevent internal polarity reversal of the stack during the stacking process, which could occur, for example, by inserting a cell with reversed polarity or by attaching a busbar and / or end plate with reversed polarity.

[0015] As a further development, it is therefore proposed that the different stack types and / or the two poles of a stack each have at least one identification feature for differentiation, preferably for visual differentiation. Using this at least one identification feature, the stack types or poles can then be reliably distinguished. In this way, polarity reversal can be prevented, both when electrically connecting two stacks and when connecting a stack to power electronics. Furthermore, polarity reversal during stacking can be prevented.

[0016] Preferably, the at least one identification feature is arranged on a current collecting plate, an end plate, a bipolar plate and / or on a sealing plate of the stacks. Since current collecting plates and end plates are each arranged in an end section of a stack, i.e. in the area of ​​a pole or in a section via which the electrical connection is made, the identification feature arranged there can be used to determine directly during connection whether the correct stack type or the correct pole has been selected. With the help of an identification feature arranged on a bipolar plate and / or on a sealing plate, in particular, polarity reversal during stacking can be avoided. With the help of an identification feature that extends across the cells of a stack, the current collecting plates and the end plates, polarity reversal can be avoided throughout.

[0017] Furthermore, the at least one identification feature is preferably a geometric feature and / or a color code. The geometric feature can, for example, be at least one elevation and / or depression. For example, embossing can be incorporated as an identification feature. Furthermore, a particular geometric configuration of a plate can indicate a specific stack type or pole.

[0018] The color code for differentiation can be a colored marking or a different color design.

[0019] Alternatively or additionally, it is proposed that the busbar for connecting two stacks or for connecting a stack to a power electronics system have a geometric design that only allows the connection of two different poles. The corresponding connection areas on the busbar can have different geometries for this purpose, for example, differently arranged holes for accommodating connecting elements.

[0020] According to a preferred embodiment of the invention, the busbar and a stack connected to the busbar have corresponding three-dimensional features that only interlock in a specific installation position of the stack. This reliably prevents polarity reversal, as this is structurally impossible ("poka-yoke" principle).

[0021] Preferred embodiments of the invention are described in more detail below with reference to the accompanying drawings. These show: Fig. 1 is a schematic representation of an electrochemical plant according to the invention with two stacks electrically connected in series; Fig. 2 a schematic representation of an end section of a stack for an electrochemical plant according to the invention and Fig. 3 a schematic representation of the end sections of two adjacent stacks of an electrochemical plant according to the invention, which are connected via a busbar. Detailed description of the drawings

[0022] The Fig. 1 shows an example of an electrochemical system 1 according to the invention, which is an electrolysis system for producing hydrogen. The system 1 in this case comprises two stacks 2 that are electrically connected in series. The stacks 2 have reversed polarity, so that they can be assigned to different stack types. In the left stack 2 (stack type A), the negative pole "-" is arranged at the top and the positive pole "+" is arranged at the bottom. In the right stack 2 (stack type B), the situation is exactly the opposite. This makes it possible to form the electrical connection between the two stacks 2 using a busbar 3 that runs parallel to the orientation of the electrolysis cells of the stacks 2. In particular, the busbar 3 does not have to be guided from an upper end section of the left stack 2 to a lower end section of the right stack 2, as is usual in the prior art.This allows the busbar 3 to be made shorter, which helps save material and costs. Furthermore, the stacks 2 remain easily accessible. The exact design of the busbar 3 is not predetermined; it can be designed, for example, as a solid metal rail, for example, made of copper, or as a flexible electrical cable.

[0023] The differences between the two stack types A and B are essentially limited to the reversed polarity. This means that the stacks 2 are otherwise constructed in the same way. In particular, they have the same media connections. These are shown in the Fig. 1 - merely by way of example - are arranged on top of the stacks 2. A first media connection 4 is used to supply water. A second media connection 5 is used to remove water and the product gas oxygen. The product gas hydrogen can be removed via a third media connection 6.

[0024] Since the Fig. Since the stacks 2 shown in Figure 1 not only need to be electrically connected to one another, but also to a power electronics system (not shown) of the system 1, each of the two stacks 2 is connected to the power electronics system via an additional busbar 3. If a system 1 comprises more than two stacks 2, at least one of the additional busbars 3 serves to connect the respective stack 2 to another stack 2. The position of the busbars 3 therefore changes from top to bottom or vice versa, analogous to the polarity of the stacks 2 to be connected.

[0025] According to the presentation of the Fig. 1, a large number of stacks 2 can thus be electrically connected in series with one another in a particularly material- and space-saving manner, provided that a stack 2 of stack type A and a stack 2 of stack type B are alternately connected to one another.

[0026] In order to be able to reliably distinguish between the stack types A, B and / or the poles of a stack 2, each stack 2 can have an identification feature 7 assigned to the respective stack type A, B or pole. As shown by way of example in the Fig. 2, the identification feature 7 can be a geometrical shape or form that allows for the identification of the stack type A, B, or pole at a glance. In this case, the geometrical shape includes beveled corners and a specific arrangement of point-like elevations. Corresponding identification features 7' can be formed on the busbar 3, so that precise assignment is possible and incorrect connection is prevented by the shape and corresponding features. This is exemplified in the Fig. 3 shown.

[0027] The identification features 7 are in the Fig. 2 and Fig.3 are each formed on a current collecting plate 8 of a stack 2. The electrical connection of a stack 2 is generally made via these. However, the identification features 7 could also be formed on an end plate 9, a bipolar plate 10, and / or a sealing plate 11 (see reference numerals in parentheses); in this case, polarity reversal during stacking of the stack 2 is also prevented.

Claims

[1] Electrochemical plant (1), in particular electrolysis plant, with several stacks (2) connected electrically in series, characterized by that the stacks (2) connected electrically in series comprise at least two stack types (A, B) which differ in that they are reversely polarized, the different stack types (A, B) being arranged alternately in the electrical series circuit. [2] Electrochemical plant (1) according to claim 1, characterized by that the electrical series connection of two adjacent stacks (2) takes place via an electrical conductor, in particular a busbar (3), which connects the two stacks (2) in the region of an upper end section or in the region of a lower end section. [3] Electrochemical plant (1) according to claim 2, characterized bythat an electrical conductor, in particular a busbar (3), which connects two upper end sections of two adjacent stacks (2), is followed by an electrical conductor or a busbar (3) which connects two lower end sections and vice versa. [4] Electrochemical plant (1) according to claim 2 or 3, characterized by that the electrical series connection of two adjacent stacks (2) is effected via a busbar (3) which runs essentially parallel to the cell planes of the two stacks (2). [5] Electrochemical plant (1) according to one of the preceding claims, characterized by that the different stack types (A, B) have media connections (4, 5, 6) which are arranged at the same location on the respective stack (2) in the final installation position of the stacks (2). [6] Electrochemical plant (1) according to one of the preceding claims, characterized bythat the different stack types (A, B) and / or the two poles of a stack (2) each have at least one identification feature (7) for differentiation, preferably for optical differentiation. [7] Electrochemical plant (1) according to claim 6, characterized by that the at least one identification feature (7) is arranged on a current collecting plate (8), an end plate (9), a bipolar plate (10) and / or on a sealing plate (11) of the stacks (2). [8] Electrochemical plant (1) according to claim 6 or 7, characterized by that the at least one identification feature (7) is a geometric characteristic and / or a color code. [9] Electrochemical plant (1) according to one of claims 2 to 8, characterized bythat the busbar (3) for connecting two stacks (2) or for connecting a stack (2) to a power electronics has a geometric design which only allows the connection of two different poles. [10] Electrochemical plant (1) according to one of claims 2 to 9, characterized by that the busbar (3) and a stack (2) connected to the busbar (3) have corresponding three-dimensional features which only engage with each other in a specific installation position of the stack (2).

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