MULTISTACK ELECTROLYSIS ARRANGEMENT

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to European Patent Application No. EP24165550.5, filed Mar. 22, 2024, the entire contents of which are incorporated herein by reference.

BACKGROUND

The invention is directed to an arrangement that comprises a plurality of electrolysis cells. The invention can be used, in particular, to produce hydrogen.

Large-scale electrolysis is usually performed with electrolysis stacks, which each comprise a plurality of electrolysis cells. During operation, an electrolyte has to be supplied to the electrolysis cells and electrolysis products such as hydrogen and oxygen have to be collected from the electrolysis cells. The electrolysis stacks therefore have respective inlet and outlet terminals. It is known to provide these terminals in the electrodes in order to reduce the number and quality of required gaskets. For example, solutions are known in which an electrolyte distributor for distributing the electrolyte to the electrolysis cells, and anolyte collector for collecting the electrolyte and the anode product and a catholyte collector for collecting the electrolyte and the cathode product are built in the electrodes. However, the more electrolysis cells are installed in an electrolysis stack, the more electrolyte is required to be supplied to the electrolysis stack and the more gas is produced. As a consequence, the electrolyte distributor, the anolyte collector and the catholyte collector must be enlarged. This, however, reduces the active area of each electrolysis cell, which in turn reduces the capacity of the electrolysis stack. This is counterproductive.

SUMMARY

The object of the invention is to provide an arrangement that can be used for an electrolysis particularly efficiently.

The object is solved with the arrangement and use according to the independent claims. Advantageous refinements are presented in the dependent claims. The features described in the claims and in the description can be combined with each other in any technologically reasonable manner.

According to the invention an arrangement is presented that comprises:

• • a first electrolysis cells unit and a second electrolysis cells unit, each respectively having a first end plate, a second end plate and a plurality of electrolysis cells arranged adjacent to each other between the first end plate and the second end plate, a first inlet for introducing an electrolyte, a first outlet arranged in the first end plate for discharging a first electrolysis product and a second outlet arranged in the second end plate for discharging the first electrolysis product, wherein each of the electrolysis cells respectively has an anode space with an anode, a cathode space with a cathode, a diaphragm that separates the anode space from the cathode space,
  • a first separator that is connected fluidly to the first outlets of both electrolysis cells units and to the second outlets of both electrolysis cells units, and that has a separator gas outlet and a separator liquid outlet,
  • a power supply that is connected electrically to both electrolysis cells units for powering an electrolysis therein.

The arrangement 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 mixture containing water. It is preferred that the arrangement is configured for alkaline electrolysis, in particular pressurized alkaline electrolysis. However, the advantages described herein can be achieved regardless of which electrolyte is used and which electrolysis products are obtained. Preferably, the arrangement is configured for high-pressure electrolysis. This should be understood as electrolysis with an operating pressure of at least 10 bar. The advantages described herein are particularly relevant in this context. Nevertheless, the described arrangement can also be used advantageously at lower pressures. The arrangement comprises two electrolysis cells units. The arrangement can have more than two electrolysis cells units that are configured analogously to the two electrolysis cells units described herein. An electrolysis cells unit is an object that comprises a plurality of electrolysis cells. The two electrolysis cells units are configured separately from each other.

In each of the electrolysis cells, electrolysis can be carried out independently of the other electrolysis cells. In order to obtain the electrolysis products in large quantities, several of the electrolysis cells are provided. The electrolysis cells are preferably lined up along an axis and held adjacent to one another. To this end, the electrolysis cells units respectively have a first end plate and a second end plate. The electrolysis cells are arranged in between the end plates. The end plates can also be referred to as pressing plates.

Preferably, the electrolysis cells are pressed together. This can be achieved, for example, using tie rods. These are rods which are arranged parallel to the electrolysis cells and through which a force is exerted on the electrolysis cells. The tie rods can be applied to the end plates.

The electrolysis cells each comprise an anode space with an anode, a cathode space with a cathode and a diaphragm arranged between the anode space and the cathode space. The anodes can be arranged inside the respective anode space or at the boundary of the respective anode space. The cathodes can be arranged inside the respective cathode space or at the boundary of the respective cathode space.

The anodes and the cathodes can each be composed of one piece of metal or of several parts. For example, the anodes and/or cathodes can each be formed by a plate and a supporting wire mesh attached to it. The anode spaces and/or the cathode spaces are preferably each designed to withstand a pressure of at least 10 bar. In general, however, it is irrelevant for the idea described herein how the anode spaces, anodes, cathode spaces and cathodes are designed. In particular, any configuration of anode spaces, anodes, cathode spaces and cathodes known from the prior art can be used.

The electrolysis cells units further each comprise a first inlet for introducing an electrolyte. The first inlet can be provided anywhere at the respective electrolysis cells units. It is preferred that the first inlet is located in the lower half of the first end plate, in particular at the bottom of the first end plate. It is sufficient to have a single inlet. In that case, the inlet can be used to introduce the electrolyte into all electrolysis cells of the respective electrolysis cells unit. However, it is preferred to have at least two inlets. Each of the inlets is then configured to introduce the electrolyte into some of the electrolysis cells. In general, the first inlet is configured for introducing the electrolyte into some or all of the electrolysis cells. In case there is a second inlet, the second inlet can be configured for introducing the electrolyte into some or all of the electrolysis cells. However, since the second inlet is not necessary, it is possible to have a configuration with a single inlet only. For simplicity, this inlet is still referred to as the first inlet herein. In general, the first inlet can be described to be configured for introducing the electrolyte into the respective electrolysis cells unit. Likewise, a second inlet can be described to be configured for introducing the electrolyte into the respective electrolysis cells unit.

The first electrolysis cells unit and/or the second electrolysis cells unit preferably comprises a first distributor that is connected to the first inlet for distributing the electrolyte and a second distributor that is connected to the second inlet for distributing the electrolyte. The first distributor and/or the second distributor can be built in the electrodes.

The electrolysis cells units further each comprise a first outlet arranged in the first end plate for discharging a first electrolysis product and a second outlet arranged in the second end plate for discharging the first electrolysis product. That is, there are at least two outlets for the same electrolysis product. The advantages described herein can be achieved if this is the case for one of the electrolysis products. Therein, it is irrelevant to which of the electrolysis products this applies. The first electrolysis product can be the anode product or the cathode product. However, the advantages described herein can be achieved particularly well in case there are at least two outlets for the first electrolysis product and at least two further outlets for the second electrolysis product.

Both the first outlet and the second outlet are configured for discharging the first electrolysis product from the respective electrolysis cells unit. It was found that having at least two outlets for the same electrolysis product increases the capacity of the electrolysis. This applies in particular because the outlets are arranged in the end plates, between which the electrolysis cells are arranged. With a respective outlet for discharging the first electrolysis product arranged in each of the end plates, the first electrolysis product can be discharged to two sides of the electrolysis cells unit. At both end plates, thereby, only a fraction of the first electrolysis product is discharged. Compared to prior art solutions where the electrolysis product is discharged to one side only, this leaves more space for the active area of the electrolysis cells. This, in turn, increases the capacity of the electrolysis.

The first electrolysis cells unit and/or the second electrolysis cells unit preferably comprises a first collector for collecting the first electrolysis product, wherein the first collector is connected to the first outlet and/or a second collector for collecting the first electrolysis product, wherein the second collector is connected to the second outlet. In case the first electrolysis product is the anode product, the first collector and the second collector can be referred to as anolyte collectors. In case the first electrolysis product is the cathode product, the first collector and the second collector can be referred to as catholyte collectors. The first collector and/or the second collector can be built in the electrodes.

The arrangement further comprises a first separator that is connected fluidly to the first outlets of both electrolysis cells units and to the second outlets of both electrolysis cells units, and that has a separator gas outlet and a separator liquid outlet. The first separator is thereby connected to the electrolysis cells units such that with the first separator the first electrolysis product can be separated from the electrolyte. To this end, the first outlets and the second outlets can be connected to a separator inlet of the first separator. Thereby, it is irrelevant if the first separator has one or more separator inlets. It is sufficient that each of the first outlets and each of the second outlets is connected to one separator inlet of the first separator. This can, but does not have to be the same separator inlet for all first outlets and second outlets. The first separator is configured to separate a mixture of a liquid and a gas introduced into the first separator and to provide the gas at the separator gas outlet and the liquid at the separator liquid outlet.

Normally, an electrolysis arrangement has an anolyte separator and a catholyte separator. This is preferred for the arrangement described herein as well. However, in order to achieve the advantages described herein, it is sufficient to have only one separator. This can be the anolyte separator or the catholyte separator. Hence, herein the first separator is described, which can be the anolyte separator or the catholyte separator. It is preferred that there is a second separator as well. However, since this is not necessary, it is possible that the arrangement has only one separator. For simplicity, this single separator will nevertheless be referred to as the first separator.

The arrangement further comprises a power supply that is connected electrically to both electrolysis cells units for powering an electrolysis therein. The power supply can be a DC power supply. In particular, any prior art power supply designed for an electrolysis can be used. The power supply provides the electrical power to the electrolysis cells that is used to operate the electrolysis cells.

Having two electrolysis cells units connected to the same power supply and to the same first separator increases the electrolysis capacity in a particularly simple way. This is particularly true compared to a solution in which instead of a single electrolysis cells unit with a respective power supply and a respective first separator two individual systems of this type are used that each comprise an electrolysis cells unit, a power supply and a first separator. Such a simple up-scaling to achieve large capacity of production would have multiple disadvantages. First, a large plot plan is required to fit the multiplied systems. Second, although engineering costs can be saved by simply copying a system, the costs for the necessary equipment are comparatively high. Third, the maintenance effort is multiplied by the number of systems. In contrast to such a simple multiplication of systems, the described arrangement comprises two electrolysis cells units that are connected to the same power supply and the same first separator. Such a bundling of electrolysis cells reduces the costs and plot size for the equipment and for corresponding maintenance.

In a preferred embodiment of the arrangement the first outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of some of the electrolysis cells of the first electrolysis cells unit and the second outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of some of the electrolysis cells of the first electrolysis cells unit,

• • or
  • the first outlet of the first electrolysis cells unit is connected fluidly to the cathode spaces of some of the electrolysis cells of the first electrolysis cells unit and the second outlet of the first electrolysis cells unit is connected fluidly to the cathode spaces of some of the electrolysis cells of the first electrolysis cells unit.

This embodiment comprises two alternatives. In the first alternative the first electrolysis product is the anode product. Hence, the first inlet and the second inlet are connected to the anode spaces. In the second alternative the first electrolysis product is the cathode product. Hence, the first inlet and the second inlet are connected to the cathode spaces. For simplicity, in the following only the first alternative will be described. However, an analogous explanation applies to the second alternative.

Ideally, the first outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of the electrolysis cells closest to the first end plate of the first electrolysis cells unit and the second outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of the electrolysis cells closest to the second end plate of the first electrolysis cells unit. This way, the anode spaces of the electrolysis cells are each connected to the nearest outlet for the anode product. However, the advantages described herein cannot only be achieved in this ideal configuration. To a reduced extent the advantages can also be achieved in any configuration in which the anode spaces of some of the electrolysis cells are connected fluidly to the first outlet and the anode spaces of some of the electrolysis cells are connected fluidly to the second outlet. In each of these configurations the amount of fluid that flows through the first outlet and through the second outlet is smaller than it would be if there was only a single outlet.

Preferably, each of the electrolysis cells is connected fluidly to the first outlet or to the second outlet, but not to both the first outlet and the second outlet. However, the described arrangement would still work if the latter was the case. The advantages described herein could thereby also be achieved to some extent.

It is sufficient for the advantages to be achieved that only one of the electrolysis cells units is configured as described with respect to this embodiment. However, additionally, it is preferred that the first outlet of the second electrolysis cells unit is connected fluidly to the anode spaces of some of the electrolysis cells of the second electrolysis cells unit and the second outlet of the second electrolysis cells unit is connected fluidly to the anode spaces of some of the electrolysis cells of the second electrolysis cells unit

• • or
  • the first outlet of the second electrolysis cells unit is connected fluidly to the cathode spaces of some of the electrolysis cells of the second electrolysis cells unit and the second outlet of the second electrolysis cells unit is connected fluidly to the cathode spaces of some of the electrolysis cells of the second electrolysis cells unit.

In a further preferred embodiment of the arrangement the first outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of a first group of the electrolysis cells of the first electrolysis cells unit and the second outlet of the first electrolysis cells unit is connected fluidly to the anode spaces of a second group of the electrolysis cells of the first electrolysis cells unit,

• • or
  • the first outlet of the first electrolysis cells unit is connected fluidly to the cathode spaces of a first group of the electrolysis cells of the first electrolysis cells unit and the second outlet of the first electrolysis cells unit is connected fluidly to the cathode spaces of a second group of the electrolysis cells of the first electrolysis cells unit. Like the previous preferred embodiment, this embodiment comprises two alternatives. In the first alternative the first electrolysis product is the anode product. Hence, the first inlet and the second inlet are connected to the anode spaces. In the second alternative the first electrolysis product is the cathode product. Hence, the first inlet and the second inlet are connected to the cathode spaces. For simplicity, in the following only the first alternative will be described. However, an analogous explanation applies to the second alternative.

Each of the electrolysis cells belongs to either the first group or the second group.

It is sufficient for the advantages to be achieved that only one of the electrolysis cells units is configured as described with respect to this embodiment. However, additionally, it is preferred that the first outlet of the second electrolysis cells unit is connected fluidly to the anode spaces of a first group of the electrolysis cells of the second electrolysis cells unit and the second outlet of the second electrolysis cells unit is connected fluidly to the anode spaces of a second group of the electrolysis cells of the second electrolysis cells unit,

• • or
  • the first outlet of the second electrolysis cells unit is connected fluidly to the cathode spaces of a first group of the electrolysis cells of the second electrolysis cells unit and the second outlet of the second electrolysis cells unit is connected fluidly to the cathode spaces of a second group of the electrolysis cells of the second electrolysis cells unit.

In a further preferred embodiment of the arrangement the first group of electrolysis cells of the first electrolysis cells unit is arranged between the first end plate of the first electrolysis cells unit and the second group of electrolysis cells of the first electrolysis cells unit, and wherein the second group of electrolysis cells of the first electrolysis cells unit is arranged between the first group of electrolysis cells of the first electrolysis cells unit and the second end plate of the first electrolysis cells unit.

In the present embodiment the distance from the electrolysis cells to the respective outlets is particularly short. Hence, the electrolysis products can be extracted from the electrolysis cells particularly easily.

Ideally, the electrolysis cells arranged adjacent to the first end plate constitute the first group and the electrolysis cells arranged adjacent to the second end plate constitute the second group. However, the advantages described herein cannot only be achieved in this ideal case.

It is sufficient for the advantages to be achieved that only one of the electrolysis cells units is configured as described with respect to this embodiment. However, additionally, it is preferred that the first group of electrolysis cells of the second electrolysis cells unit is arranged between the first end plate of the second electrolysis cells unit and the second group of electrolysis cells of the second electrolysis cells unit, and wherein the second group of electrolysis cells of the second electrolysis cells unit is arranged between the first group of electrolysis cells of the second electrolysis cells unit and the second end plate of the second electrolysis cells unit.

In a further preferred embodiment of the arrangement the electrolysis cells of the first group of electrolysis cells of the first electrolysis cells unit form a first electrolysis stack of the first electrolysis cells unit, and wherein the electrolysis cells of the second group of electrolysis cells of the first electrolysis cells unit form a second electrolysis stack of the first electrolysis cells unit.

Since the electrolysis cells of the first group are connected to the first outlet and the electrolysis cells of the second group are connected to the second outlet, the first electrolysis product can be discharged separately for the two groups. In the present embodiment, however, the groups of electrolysis cells are separated from each other even further. In order to constitute separate electrolysis stacks, the groups of electrolysis stacks must be connected to the power supply such that the electrolysis stacks can be distinguished from each other. An electrolysis stack has electrolysis cells arranged next to each other with the anodes and cathodes being arranged alternatingly. An electrolysis cells unit can have two electrolysis stacks in that the two electrolysis stacks are arranged “back-to-back”. That is, from the first end plate to the second end plate the anodes and cathodes are, in general, arranged alternatingly. However, at the interface of the first group and the second group this sequence changes from anode-cathode to cathode-anode. The preferred embodiment described below is an example of how this configuration can be achieved.

It is sufficient for the advantages to be achieved that only one of the electrolysis cells units is configured as described with respect to this embodiment. However, additionally, it is preferred that the electrolysis cells of the first group of electrolysis cells of the second electrolysis cells unit form a first electrolysis stack of the second electrolysis cells unit, wherein the electrolysis cells of the second group of electrolysis cells of the second electrolysis cells unit form a second electrolysis stack of the second electrolysis cells unit.

In a further preferred embodiment of the arrangement the power supply has a first terminal that is connected electrically to a central plate of the first electrolysis cells unit arranged between the first end plate and the second end plate of the first electrolysis cells unit, wherein the power supply has a second terminal that is connected electrically to a central plate of the second electrolysis cells unit arranged between the first end plate and the second end plate of the second electrolysis cells unit, wherein the first end plate of the first electrolysis cells unit is connected electrically to the first end plate of the second electrolysis cells unit, and wherein the second end plate of the first electrolysis cells unit is connected electrically to the second end plate of the second electrolysis cells unit.

In the present embodiment the two electrolysis cells units each can be considered to have two electrolysis stacks in that the power supply is connected to the electrolysis cells units such that at the central plate the sequence changes from anode-cathode to cathode-anode. The central plate is not a bipolar plate, since it provides the lower or the higher potential to both electrolysis cells that are arranged adjacent to the central plate. A bipolar plate, in contrast, provides the lower potential to one of the adjacent electrolysis cells and the higher potential to the other electrolysis cell. This is possible because the terms “lower” and “higher” have be seen relative to the potential applied at the other side of the respective electrolysis cell.

In the present embodiment the two electrolysis cells units are powered by the same power supply. This is beneficial since a single power supply is sufficient. Also, this adds a further aspect of how the two electrolysis cells units are interrelated with each other.

The described way of how the two electrolysis cells units are connected to the power supply was found to be particularly advantageous. In particular, the two electrolysis cells units are connected in parallel, which means that comparatively low voltages are sufficient, in particular compared to a configuration in which the two electrolysis cells units are connected to the power supply in series. Providing sufficiently high voltages for such a configuration could be difficult. Also, connecting the end plates with each other was found to be a particularly simple configuration.

Also, in the present embodiment the two end plates of the first electrolysis cells unit are on the same electrical potential and the two end plates of the second electrolysis cells unit are on the same electrical potential. Having the two end plates of an electrolysis cells unit at the same electrical potential has the advantage that there is no electrical voltage between the two end plates. This is advantageous, for example, in the preferred case that the electrolysis cells unit comprises tie rods, by means of which the electrolysis cells are pressed against each other. For example, the electrolysis cells unit can have a first holding plate and a second holding plate, which are connected to each other by multiple tie rods, wherein the end plates and the electrolysis cells are arranged in between the two holding plates. The first holding plate and the first end plate are preferably separated by a first electrical insulation. The second holding plate and the second end plate are preferably separated by a second electrical insulation. Any electrical voltage between the two end plates would require the first and second electrical insulation to be particularly strong. Should either of these insulations fail, a current could flow through the tie rods. This can be prevented in the present embodiment by having the two end plates on the same electrical potential. In a further preferred embodiment of the arrangement each of the electrolysis cells units respectively further has a third outlet arranged in the first end plate for discharging a second electrolysis product and a fourth outlet arranged in the second end plate for discharging the second electrolysis product, wherein the arrangement further comprises a second separator that is connected fluidly to the third outlets of both electrolysis cells units and to the fourth outlets of both electrolysis cells units and that has a separator gas outlet and a separator liquid outlet.

Above, it had been stated that it is sufficient to have at least two outlets for one of the electrolysis products. However, the advantages described herein can be obtained particularly well in case there are at least two respective outlets for both electrolysis products. This is what the present embodiment is directed to. Consequently, there is also a second separator.

The above description of the first and second outlet and the first separator applies analogously to the third and fourth outlet and the second separator, respectively. The first electrolysis cells unit and/or the second electrolysis cells unit preferably comprises a third collector for collecting the second electrolysis product, wherein the third collector is connected to the third outlet and/or a fourth collector for collecting the second electrolysis product, wherein the fourth collector is connected to the fourth outlet. In case the second electrolysis product is the anode product, the third collector and the fourth collector can be referred to as anolyte collectors. In case the second electrolysis product is the cathode product, the third collector and the fourth collector can be referred to as catholyte collectors. The third collector and/or the fourth collector can be built in the electrodes.

The arrangement comprises the second separator that is connected fluidly to the third outlets of both electrolysis cells units and to the fourth outlets of both electrolysis cells units, and that has a separator gas outlet and a separator liquid outlet. The second separator is thereby connected to the electrolysis cells units such that with the second separator the second electrolysis product can be separated from the electrolyte. To this end, the third outlets and the fourth outlets can be connected to a separator inlet of the second separator. Thereby, it is irrelevant if the second separator has one or more separator inlets. It is sufficient that each of the third outlets and each of the fourth outlets is connected to one separator inlet of the second separator. This can, but does not have to be the same separator inlet for all third outlets and fourth outlets. The second separator is configured to separate a mixture of a liquid and a gas introduced into the second separator and to provide the gas at the separator gas outlet and the liquid at the separator liquid outlet. In a further preferred embodiment of the arrangement the third outlets of the first electrolysis cells unit are connected fluidly to the cathode spaces of some of the electrolysis cells of the first electrolysis cells unit, wherein the fourth outlets of the first electrolysis cells unit are connected fluidly to the cathode spaces of some of the electrolysis cells of the first electrolysis cells unit.

Above, it had been described that the first electrolysis product can either be the anode product or the cathode product. The present embodiment is limited to the alternative in which the first electrolysis product is the anode product. However, in the present embodiment there are two outlets for the cathode product as well. Here, the cathode product can be referred to as a second electrolysis product. That is, in the present embodiment there are at least two outlets for the anode product and at least two outlets for the cathode product. The advantages described herein can thus be achieved particularly well.

Preferably, the third outlets of the first electrolysis cells unit are connected fluidly to the cathode spaces of the first group of the electrolysis cells of the first electrolysis cells unit, wherein the fourth outlets of the first electrolysis cells unit are connected fluidly to the cathode spaces of the second group of the electrolysis cells of the first electrolysis cells unit.

It is sufficient for the advantages to be achieved that only one of the electrolysis cells units is configured as described with respect to this embodiment. However, additionally, it is preferred that the third outlets of the second electrolysis cells unit are connected fluidly to the cathode spaces of some of the electrolysis cells of the second electrolysis cells unit, wherein the fourth outlets of the second electrolysis cells unit are connected fluidly to the cathode spaces of some of the electrolysis cells of the second electrolysis cells unit. Preferably, the third outlets of the second electrolysis cells unit are connected fluidly to the cathode spaces of the first group of the electrolysis cells of the second electrolysis cells unit, wherein the fourth outlets of the second electrolysis cells unit are connected fluidly to the cathode spaces of the second group of the electrolysis cells of the second electrolysis cells unit. In a further preferred embodiment of the arrangement the first inlet of the first electrolysis cells unit is arranged in the first end plate of the first electrolysis cells unit, wherein the first electrolysis cells unit further has a second inlet arranged in the second end plate of the first electrolysis cells unit for introducing the electrolyte,

• • and/or
  • wherein the first inlet of the second electrolysis cells unit is arranged in the first end plate of the second electrolysis cells unit, and wherein the second electrolysis cells unit further has a second inlet arranged in the second end plate of the second electrolysis cells unit for introducing the electrolyte.

Above, it had been stated that it is sufficient for both electrolysis cells units to each have a single inlet. In the present embodiment, however, this is specified in that the first electrolysis cells unit and/or the second electrolysis cells unit respectively has at least two inlets. The “and”-case is preferred.

Having two inlets arranged in the end plates means that the electrolyte can be introduced into the respective electrolysis cells unit from two sides. This reduces the amount of electrolyte that has to be introduced via each of the inlets. Compared to prior art solutions where the electrolyte is introduced from one side only, this leaves more space for the active area of the electrolysis cells.

The first inlet is preferably configured to introduce the electrolyte into some of the electrolysis cells and the second inlet is preferably configured to introduce the electrolyte into some of the electrolysis cells. To this end, with any configuration the advantages described herein can be achieved to some extent. Ideally, the first inlet is configured to introduce the electrolyte into the first group of the electrolysis cells and the second inlet is configured to introduce the electrolyte into the second group of the electrolysis cells. Thereby, the electrolysis cells are separated into the groups particularly clearly. This can facilitate maintenance.

This applies in particular in the preferred case that for both electrolysis cells units the electrolysis cells of the first group are connected fluidly to the first inlet, the first outlet and the third outlet that for both electrolysis cells units the electrolysis cells of the second group are connected fluidly to the second inlet, the second outlet and the fourth outlet and that the power supply is connected to both electrolysis cells units such that the electrolysis cells of the first group and the electrolysis cells of the second group of the electrolysis cells units form a respective electrolysis stack. However, for the basic concept of the idea described herein such a clear separation is not necessary.

As a further aspect of the invention a use of an arrangement configured as described herein for performing an electrolysis is presented.

The advantages and features of the arrangement are transferrable to the described use, and vice versa.

As a further aspect of the invention an arrangement is presented that comprises:

• • an electrolysis cells unit having a first end plate, a second end plate, and a plurality of electrolysis cells arranged adjacent to each other between the first end plate and the second end plate, a first inlet for introducing an electrolyte, a first outlet arranged in the first end plate for discharging a first electrolysis product and a second outlet arranged in the second end plate for discharging the first electrolysis product, wherein each of the electrolysis cells respectively has an anode space with an anode, a cathode space with a cathode and a diaphragm that separates the anode space from the cathode space,
  • a separator that is connected fluidly to the first outlet of the electrolysis cells unit and to the second outlet of the electrolysis cells unit, and that has a separator gas outlet and a separator liquid outlet,
  • a power supply that is connected electrically to the electrolysis cells unit for powering an electrolysis therein.

The advantages and features of the previously described arrangement and the use are transferrable to the currently described arrangement, and vice versa.

In contrast to the previously described arrangement, it is sufficient for the currently described arrangement to have a single electrolysis cells unit. This electrolysis cells unit is preferably configured like the first electrolysis cells unit of the previously described arrangement. That is, the above description regarding the first electrolysis cells unit of the previously described arrangement applies to the electrolysis cells unit of the currently described arrangement as well.

It was found that having two outlets for the same electrolysis product is beneficial in this general case as well. This is because the due to these two outlets at both end plates only a fraction of the first electrolysis product is discharged. Compared to prior art solutions where the electrolysis product is discharged to one side only, this leaves more space for the active area of the electrolysis cells. This, in turn, increases the capacity of the electrolysis.

It is preferred that the first inlet is provided in the first end plate and that the electrolysis cells unit has a second inlet for introducing an electrolyte arranged in the second end plate. Also, it is preferred that the electrolysis cells unit has a third outlet arranged in the first end plate for discharging a second electrolysis product and a fourth outlet arranged in the second end plate for discharging the second electrolysis product. This way, the advantage described in the previous paragraph can also be achieved with respect to introducing the electrolyte into the electrolysis cells and/or with respect to discharging the second electrolysis product.

In a preferred embodiment of the arrangement the first outlet of the electrolysis cells unit is connected fluidly to the anode spaces of a first group of the electrolysis cells of the electrolysis cells unit and the second outlet of the electrolysis cells unit is connected fluidly to the anode spaces of a second group of the electrolysis cells of the electrolysis cells unit

• • or
  • wherein the first outlet of the electrolysis cells unit is connected fluidly to the cathode spaces of a first group of the electrolysis cells of the electrolysis cells unit and the second outlet of the electrolysis cells unit is connected fluidly to the cathode spaces of a second group of the electrolysis cells of the electrolysis cells unit,
  • in that a conduit is provided that is connected with a first end to the first outlet and with a second end to the second outlet, wherein a plugging element is provided within the conduit between the first group of the electrolysis cells and the second group of the electrolysis cells.

As also described above with respect to the previously described arrangement, this embodiment comprises two alternatives. Both alternatives are achieved in that a conduit is provided that is connected with a first end to the first outlet and with a second end to the second outlet, wherein a plugging element is provided within the conduit between the first group of the electrolysis cells and the second group of the electrolysis cells. The conduit can be referred to as a collector.

The conduit extends between the first end plate and the second end plate all the way through the arrangement. That is, in general the conduit would connect the first outlet and the second outlet to each other. This is advantageous because such a configuration simplifies the manufacture of the arrangement. However, having a conduit extend all the way through the arrangement could result in electrolysis taking place where it is not desired, in particular within the conduit. This is because the conduit bypasses the diaphragms of the electrolysis cells. This allows ionic conduction through the conduit. Having electrolysis within the conduit is disadvantageous, in particular because thereby hydrogen and oxygen could be generated within the same space. This could result in an explosive gas mixture. In the present embodiment, however, this potential problem is solved in that a plugging element is provided within the conduit between the first group of the electrolysis cells and the second group of the electrolysis cells. The plugging element plugs the conduits. That is, the plugging element divides the conduit into two parts, one for each of the groups of electrolysis cells.

In the preferred case that the first inlet is provided in the first end plate and that the electrolysis cells unit has a second inlet for introducing an electrolyte arranged in the second end plate, an analogous configuration is preferred with respect to the first inlet and the second inlet. That is, a second conduit is preferably provided that is connected with a first end to the first inlet and with a second end to the second inlet, wherein a plugging element is provided within the second conduit between the first group of the electrolysis cells and the second group of the electrolysis cells.

In the preferred case that the electrolysis cells unit has a third outlet arranged in the first end plate for discharging a second electrolysis product and a fourth outlet arranged in the second end plate for discharging the second electrolysis product, an analogous configuration is preferred with respect to the third outlet and the fourth outlet. That is, a third conduit is preferably provided that is connected with a first end to the third outlet and with a second end to the fourth outlet, wherein a plugging element is provided within the third conduit between the first group of the electrolysis cells and the second group of the electrolysis cells.

As an alternative to the currently described embodiment, two separate conduits could be used. This would have the same effect in view of the electrolysis operation. In a further preferred embodiment of the arrangement the power supply has a first terminal that is connected electrically to a central plate of the electrolysis cells unit arranged between the first end plate and the second end plate of the electrolysis cells unit, and wherein the power supply has a second terminal that is connected electrically to both end plates of the electrolysis cells unit.

In the present embodiment the two end plates are at the same electrical potential. The electrolysis cells can be considered to be divided into two electrolysis stacks that are arranged “back-to-back”, with the central plate arranged in between these two electrolysis stacks.

Having the two end plates at the same electrical potential has the advantage that there is no electrical voltage between the two end plates. This is advantageous, for example, in the preferred case that the electrolysis cells unit comprises tie rods, by means of which the electrolysis cells are pressed against each other. For example, the electrolysis cells unit can have a first holding plate and a second holding plate, which are connected to each other by multiple tie rods, wherein the end plates and the electrolysis cells are arranged in between the two holding plates. The first holding plate and the first end plate are preferably separated by a first electrical insulation. The second holding plate and the second end plate are preferably separated by a second electrical insulation. Any electrical voltage between the two end plates would require the first and second electrical insulation to be particularly strong. Should either of these insulations fail, a current could flow through the tie rods. This can be prevented in the present embodiment by having the two end plates on the same electrical potential.

In a further preferred embodiment of the arrangement the first inlet is connected fluidly to the anode spaces of a first group of the electrolysis cells, wherein for the electrolysis cells of the first group the respective anode space is connected fluidly to the respective cathode space.

It is further preferred that the second inlet is connected fluidly to the anode spaces of a second group of the electrolysis cells, wherein for the electrolysis cells of the second group the respective anode space is connected fluidly to the respective cathode space.

The first group and the second group of the electrolysis cells are the same groups that have also been described above.

In general, the first inlet and optionally the second inlet can be used to introduce the electrolyte into the anode spaces and the cathode spaces. For this purpose, the inlets could be directly connected to the respective anode spaces and the cathode spaces. However, for practical reasons this might be difficult to achieve in view of available space. Thus, in the present embodiment only the anode spaces are directly connected fluidly to the respective inlet. The electrolyte can thereby be supplied directly to the anode spaces. Also, the electrolyte can be supplied to the cathode spaces indirectly via the anode spaces. This is possible because the anode spaces and the cathode spaces are connected to each other.

In general, the electrolyte could also be introduced into the cathode spaces directly and from the cathode spaces to the respective anode spaces. However, it was found for the case of water electrolysis that it is better to have oxygen mixed into hydrogen than hydrogen mixed into oxygen. This is because oxygen molecules are larger and thus less likely to penetrate through the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described with respect to the figures. The figures show a preferred embodiment, to which the invention is not limited. The figures and the dimensions shown therein are only schematic. The figures show:

FIG. 1: a first embodiment of an arrangement according to the invention,

FIG. 2: one of the electrolysis cells units of the arrangement of FIG. 1 in a first embodiment,

FIG. 3: one of the electrolysis cells units of the arrangement of FIG. 1 in a second embodiment,

FIG. 4: a second embodiment of an arrangement according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows an arrangement 1 that can be used for performing an electrolysis, in particular pressurized alkaline water electrolysis. The arrangement 1 comprises a first electrolysis cells unit 2 and a second electrolysis cells unit 3. Each of the electrolysis cells units 2,3 respectively has a first end plate 4, a second end plate 5 and a plurality of electrolysis cells 6 arranged adjacent to each other between the first end plate 4 and the second end plate 5. Further, each of the electrolysis cells units 2,3 respectively has a first inlet 7 arranged in the first end plate 4 for introducing an electrolyte, a second inlet 8 arranged in the second end plate 5 for introducing the electrolyte, a first outlet 9 arranged in the first end plate 4 for discharging a first electrolysis product, a second outlet 10 arranged in the second end plate 5 for discharging the first electrolysis product, a third outlet 11 arranged in the first end plate 4 for discharging a second electrolysis product and a fourth outlet 12 arranged in the second end plate 5 for discharging the second electrolysis product.

The arrangement 1 further comprises a first separator 18, having two separator inlets 20 by means of which the first separator 18 is connected fluidly to the first outlets 9 of both electrolysis cells units 2,3 and to the second outlets 10 of both electrolysis cells units 2,3, and having a separator gas outlet 21 and a separator liquid outlet 22. The arrangement 1 further comprises a second separator 19, having two separator inlets 20 by means of which the second separator 19 is connected fluidly to the third outlets 11 of both electrolysis cells units 2,3 and to the fourth outlets 12 of both electrolysis cells units 2,3, and having a separator gas outlet 21 and a separator liquid outlet 22.

The arrangement 1 further comprises a power supply 23 that is connected electrically to both electrolysis cells units 2,3 for powering an electrolysis therein. The power supply 23 has a first terminal 28 that is connected electrically to a central plate 30 of the first electrolysis cells unit 2 arranged between the first end plate 4 and the second end plate 5 of the first electrolysis cells unit 2. The power supply 23 has a second terminal 29 that is connected electrically to a central plate 30 of the second electrolysis cells unit 3 arranged between the first end plate 4 and the second end plate 5 of the second electrolysis cells unit 3. The first end plate 4 of the first electrolysis cells unit 2 is connected electrically to the first end plate 4 of the second electrolysis cells unit 3. The second end plate 5 of the first electrolysis cells unit 2 is connected electrically to the second end plate 5 of the second electrolysis cells unit 3.

Both electrolysis cells units 2,3 respectively have a first group 24 of the electrolysis cells 6 and a second group 25 of the electrolysis cells 6. The first group 24 is arranged between the first end plate 4 and the second group 25. The second group 25 is arranged between the first group 24 and the second end plate 5. The central plate 30 is provided in between the groups 24,25. The electrolysis cells 6 of the first group 24 form a first electrolysis stack 26 and the electrolysis cells 6 of the second group 25 form a second electrolysis stack 27. In total, there are four electrolysis stacks 26,27.

The first inlet 7 is provided for introducing an electrolyte into the electrolysis cells 6 of the first group 24. The second inlet 8 is provided for introducing the electrolyte into the electrolysis cells 6 of the second group 25. The first outlet 9 is provided for discharging an anode product from the electrolysis cells 6 of the first group 24. The second outlet 10 is provided for discharging the anode product from the electrolysis cells 6 of the second group 25. The third outlet 11 is provided for discharging a cathode product from the electrolysis cells 6 of the first group 24. The fourth outlet 12 is provided for discharging the cathode product from the electrolysis cells 6 of the second group 25.

FIG. 2 shows one of the electrolysis cells units 2,3 of FIG. 1 in more detail. Since both electrolysis cells units 2,3 are identical, FIG. 2 applies to both electrolysis cells units 2,3. From FIG. 2 it can be seen that each of the electrolysis cells 6 respectively has an anode space 13 with an anode 14, a cathode space 15 with a cathode 16 and a diaphragm 17 that separates the anode space 13 from the cathode space 15. For simplicity, the reference numerals 13 to 17 are shown for two of the electrolysis cells 6 only.

Also, it is indicated how the first inlet 7 is connected fluidly to the anode spaces 13 and the cathode spaces 15 of the electrolysis cells 6 of the first group 24 of the electrolysis cells 6, the second inlet 8 is connected fluidly to the anode spaces 13 and the cathode spaces 15 of the electrolysis cells 6 of a second group 25 of the electrolysis cells 6, the first outlet 9 is connected fluidly to the anode spaces 13 of the electrolysis cells 6 of the first group 24 of the electrolysis cells 6, the second outlet 10 is connected fluidly to the anode spaces 13 of the electrolysis cells 6 of the second group 25 of the electrolysis cells 6, the third outlet 11 is connected fluidly to the cathode spaces 15 of the electrolysis cells 6 of the first group 24 of the electrolysis cells 6 and the fourth outlet 12 is connected fluidly to the cathode spaces 15 of the electrolysis cells 6 of the second group 25 of the electrolysis cells 6. The electrolysis cells 6 of the first group 24 of the electrolysis cells 6 constitute the first electrolysis stack 26. The electrolysis cells 6 of the second group 25 of the electrolysis cells 6 constitute the second electrolysis stack 27.

The electrolysis cells 6 are arranged adjacent to each other between the first end plate 4 and the second end plate 5. In between neighboring electrolysis cells 6 of the first group 24 of the electrolysis cells 6, a respective bipolar plate 31 is provided. In between neighboring electrolysis cells 6 of the second group 25 of the electrolysis cells 6, a respective bipolar plate 31 is provided. In between the first group 24 of the electrolysis cells 6 and the second group 25 of the electrolysis cells 6, the central plate 30 is provided. The central plate 30 is connected electrically to the power supply 23 as is shown in FIG. 1. This distinguishes the central plate 30 from the bipolar plates 31. The connection to the power supply defines which of the electrodes are anodes 14 and which of the electrodes are cathodes 16. Consequently, this also defines which of the spaces are anode spaces 13 and which of the spaces are cathode spaces 15.

FIG. 3 shows one of the electrolysis cells units 2,3 of FIG. 1 in an alternative embodiment compared to FIG. 2. In contrast to the embodiment of FIG. 2, in the embodiment of FIG. 3 a conduit 32 is provided that is connected with a first end to the first outlet 9 and with a second end to the second outlet 10. A plugging element 33 is provided within the conduit 32 between the first group of the electrolysis cells 6 and the second group 25 of the electrolysis cells 6. Analogously, respective conduits 32 with a respective plugging element 33 are also provided for the third outlet 11 and the fourth outlet 12 as well as for the first inlet 7 and the second inlet 8.

FIG. 4 shows an alternative to the embodiment of FIG. 1. FIG. 4 shows an arrangement 1 that comprises an electrolysis cells unit 2. The electrolysis cells unit 2 can be configured like the one shown in FIG. 2 or like the one shown in FIG. 3. The electrolysis cells unit 2 has a first end plate 4, a second end plate 5, and a plurality of electrolysis cells 6 arranged adjacent to each other between the first end plate 4 and the second end plate 5, a first inlet 7 arranged in the first end plate 4 for introducing an electrolyte, a second inlet 8 arranged in the second end plate 5 for introducing the electrolyte, a first outlet 9 arranged in the first end plate 4 for discharging a first electrolysis product and a second outlet 10 arranged in the second end plate 5 for discharging the first electrolysis product, a third outlet 11 arranged in the first end plate 4 for discharging a second electrolysis product and a forth outlet 12 arranged in the second end plate 5 for discharging the second electrolysis product. Each of the electrolysis cells 6 respectively has an anode space 13 with an anode 14, a cathode space 15 with a cathode 16 and a diaphragm 17 that separates the anode space 13 from the cathode space 15.

The arrangement 1 further comprises a first separator 18, having two separator inlets 20 by means of which the first separator 18 is connected fluidly to the first outlet 9 of the electrolysis cells unit 2 and to the second outlet 10 of the electrolysis cells unit 2, and having a separator gas outlet 21 and a separator liquid outlet 22. The arrangement 1 further comprises a second separator 19, having two separator inlets 20 by means of which the second separator 19 is connected fluidly to the third outlet 11 of the electrolysis cells unit 2 and to the fourth outlet 12 of the electrolysis cells unit 2, and having a separator gas outlet 21 and a separator liquid outlet 22. The arrangement 1 further comprises a power supply 23 that is connected electrically to the electrolysis cells unit 2 for powering an electrolysis therein. The power supply 23 has a first terminal 28 that is connected electrically to a central plate 30 of the electrolysis cells unit 2 arranged between the first end plate 4 and the second end plate 5 of the electrolysis cells unit 2. The power supply 23 also has a second terminal 29 that is connected electrically to both end plates 4,5 of the electrolysis cells unit 2.

LIST OF REFERENCE NUMERALS

• • 1 arrangement
  • 2 first electrolysis cells unit
  • 3 second electrolysis cells unit
  • 4 first end plate
  • 5 second end plate
  • 6 electrolysis cells
  • 7 first inlet
  • 8 second inlet
  • 9 first outlet
  • 10 second outlet
  • 11 third outlet
  • 12 fourth outlet
  • 13 anode space
  • 14 anode
  • 15 cathode space
  • 16 cathode
  • 17 diaphragm
  • 18 first separator
  • 19 second separator
  • 20 separator inlet
  • 21 separtor gas outlet
  • 22 separator liquid outlet
  • 23 power supply
  • 24 first group
  • 25 second group
  • 26 first electrolysis stack
  • 27 second electrolysis stack
  • 28 first terminal
  • 29 second terminal
  • 30 central plate
  • 31 bipolar plate
  • 32 conduit
  • 33 plugging element