CN117242210A

CN117242210A - Electrolysis device

Info

Publication number: CN117242210A
Application number: CN202280028367.7A
Authority: CN
Inventors: 马克·哈内布特; 西蒙·基斯利希; 托马斯·普鲁克尔
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2021-04-14
Filing date: 2022-02-09
Publication date: 2023-12-15
Also published as: CA3216661A1; EP4274919A1; WO2022218582A1; EP4074863A1

Abstract

The invention relates to an electrolysis device (60) comprising: a plurality of electrolytic cells (12) electrically connected in series and arranged one after the other at least partially in a stacking direction (14), wherein the series connection is electrically couplable to an electrical energy source (16); a cell supply unit (18) for supplying at least one operating substance to the electrolytic cell (12) for normal operation; and a supply line (24) connected to the cell supply unit (18) and to the opposite ends (20, 22) of the successive electrolytic cells (12). According to the invention, the negative potential (34) of the electrical energy source (16) can be electrically coupled to a reference potential of the battery supply unit (18).

Description

Electrolysis device

Technical Field

The present invention relates to an electrolysis apparatus having: a plurality of cells electrically connected in series and arranged one after the other at least partially in the stacking direction, wherein the series connection is electrically couplable to a source of electrical energy; a cell supply unit for supplying at least one operating substance to the electrolytic cell for normal operation; and a supply line connected to the cell supply unit and to opposite ends of the electrolytic cells arranged one after the other.

Background

Electrolytic cells for converting chemicals into other chemicals under the action of electricity are widely known in the art. Typically, chemical reactions, i.e. substance transformations, are induced by means of an electric current. This is called electrolysis. One known and widely used form of electrolysis is water electrolysis. In water electrolysis, electricity is used to split water into its constituent parts, namely hydrogen and oxygen. In principle, however, other substances can also undergo electrolysis, for example carbon dioxide or the like.

In general, this involves fluid substances which can be fed via corresponding feed lines to an electrolytic cell in which the actual electrolysis is carried out. The electrolysis products are likewise usually in fluid form and are led out of the electrolysis cell via a further supply line. The supply lines are typically connected to a cell supply unit for supplying the electrolytic cell with the respective substance or with at least one operating substance for normal operation. In other words, the supply here means not only the transport of the operating substance or the substance to be electrolyzed, but also the removal of the corresponding electrolysis products.

The provision of hydrogen has proven to be of particular industrial interest, in particular hydrogen can be an energy carrier which can be used in a versatile manner. Hydrogen can be supplied by means of an electrolysis device, also called an electrolyzer, using regeneratively produced electrical energy. One possibility for generating hydrogen consists in using an electrolysis device whose cells are based on proton exchange membranes (English: proton exchange membrane, PEM). The principle of PEM-based electrolysers or PEM-based cells is known in the art and is therefore not further elucidated. An electrolytic cell for producing hydrogen and oxygen from water is disclosed, for example, by DE 10 2011 007 759Al. DE 10 2019 205 316Al, however, also discloses a corresponding electrolytic cell for energy-efficient oxygen production. Furthermore, DE 21 2018 000 414Ul discloses a hydrogen generation system.

A typical electrolysis device typically has a plurality of electrolysis cells, which are typically electrically connected in series. The series connection thus formed is electrically coupled to a source of electrical energy providing a suitable voltage, so that a predetermined process of electrochemical mass transfer can be achieved by means of the electrolytic cell.

Furthermore, the cells are arranged one after the other in the stacking direction such that the cells form a cell stack. By stacking, it is possible for the electrolytic cells arranged one after the other to be in direct electrical contact, so that the individual electrical terminals of the electrolytic cells can be reduced to a great extent.

Within the cell stack, a supply line system (english: manifold) is also provided, which serves to supply or remove at least one operating substance from the electrolytic cell. The operating substance can, for example, comprise a transported fluid, for example water, and/or reaction products, for example hydrogen and oxygen. Chi Duidie (English: stack) is usually operated with a specific electrolytic power such that the current is as small as possible, but the voltage is as large as possible. This is achieved by suitably stacking the cells in a cell stack. The voltages across the respective cells in the cell stack can thereby be summed to the cell stack voltage, while the cells connected in series in this manner can be operated at substantially the same current.

The electrolytic power is provided by an energy source which for this purpose is connectable to the respective opposite ends of the cell stack. A plurality of electrolytic cells, for example more than 100 electrolytic cells, in particular hundreds of electrolytic cells, can be provided in the cell stack, however preferably no more than about 400 electrolytic cells. The voltage at a corresponding one of the cells is about 1.5V to 2.5V when the water is hydrolyzed into hydrogen and oxygen. The voltage across the cell stack is correspondingly derived from this, so that the voltage at the cell stack is typically over 100V, even possibly hundreds of volts.

In addition to the cell stack, the electrolysis device also comprises other components required for the normal operation of the electrolysis device or the electrolysis cell, such as pumps, heat exchangers, separation vessels. The component is currently constituted by a cell supply unit for supplying the electrolytic cell with at least one operating substance for normal operation.

The cell supply unit is connected to the electrolytic cells arranged one after the other in the stacking direction via supply lines connected to opposite ends of the electrolytic cells arranged one after the other. The supply line is typically formed of a material such as metal.

A correspondingly high voltage occurs between the ends of the cell stack or of the electrolytic cells arranged one after the other. For supply lines which are usually formed from metal, it is therefore necessary for the supply lines to have corresponding electrically insulating sections for avoiding a connection between the ends of the electrolytic cells arranged one after the other, and thus between the electrical terminals of the electrical energy source, which can be conducted well.

Although the use according to the prior art has proven suitable in principle, it has been found that corrosion may occur in particular in the region of the supply line connected to the electrically insulating section, which is loaded with a positive potential of the electrical energy source during normal operation. This is not only detrimental to the electrolysis device itself, but may also lead to contamination of at least one operating substance, which may lead to disturbances in the normal operation of the electrolysis cell.

In order to reduce the problems mentioned, it is known in the prior art to keep the specific conductivity of the water as small as possible and to dynamically suppress corrosion by means of as long insulation segments or a reduction in cross section as possible in the region of the respective insulation segments, so that the effect is stretched over time. However, corrosion is thus in principle unavoidable. In particular, the always present, even low, electrical conductivity of the water, in particular in the insulation segments formed by the insulation segments, leads to stray currents in the water, in particular in the insulation segments. Thus, the problem of corrosion still continues to exist.

Disclosure of Invention

The present invention is based on the object of reducing the so-called corrosion problem.

As a solution, the invention proposes an electrolysis device according to independent claim 1.

Advantageous developments are found in the features of the dependent claims.

With regard to the generic electrolysis installation, it is proposed, in particular, by means of the invention that the negative potential of the electrical energy source can be electrically coupled to the reference potential of the cell supply unit. Thus, in operation of the electrolysis device, the negative potential of the source of electrical energy is electrically coupled to the reference potential of the cell supply unit.

The invention is based on the following basic idea, inter alia: the construction according to the invention of the electrolysis device makes it possible, preferably, for the cell supply unit and thus also the end of the cell stack formed by the successive electrolysis cells, which end is connected to the negative potential of the electrical energy source, to have a minimum potential of the electrolysis device. The end of the cell stack is also referred to as first end in the following.

The electrical connection can be achieved by: the first end of Chi Duidie is connected to a reference potential of the cell supply unit by means of an electrical line. The reference potential of the cell supply unit can be, for example, the ground potential of the cell supply unit. The reference potential of the cell supply unit can be electrically coupled, for example indirectly or directly, to ground potential. Furthermore, it can of course also be provided that the supply line is formed at least in part from an electrically conductive material. In particular, the material of the supply line can have metal. It is thereby possible, independently of the electrical lines, to provide an electrical conductivity, more precisely also by means of at least one of the supply lines, if at least one of the supply lines provides an electrical conductivity over its entire longitudinal extension (like an electrical line).

It will be appreciated that this can of course only be applied to the supply line connected to the first end of the cell stack. At least, the supply line connected to the second end of the cell stack opposite the first end of the cell stack has an insulating section, so that the second end of the cell stack is prevented from being electrically connected to a reference potential of the cell supply unit.

If an electrical connection is made by means of an electrical line, all supply lines can have corresponding insulating sections, in particular if the supply lines have essentially metal as material. However, the supply line can also be formed from an electrically insulating material.

In particular, the section of the supply line facing the cell supply unit up to the optionally present corresponding insulation section does not need to have a potential which is smaller than the potential of the cell supply unit, in particular smaller than the reference potential. In this way, corrosion effects can be largely avoided in the region of the supply lines between the respective insulation sections, which are optionally present, and the tank supply unit. The corrosion problem can thus be transferred to the respectively opposite sides of the respective electrically insulating section, in the region of which a corresponding additional treatment can be provided, in order to largely avoid or even completely prevent corrosion effects in this case too.

This can be achieved in particular by: the electrolytic cells arranged one after the other are no longer potentioless with respect to the cell supply unit, but by means of the construction according to the invention it is ensured that the cell supply unit always provides a minimum potential in the electrolysis device. The electrolytic cells of Chi Duidie which are arranged one behind the other are in this case also generally electrically connected in series.

That is, by the configuration according to the present invention, in particular, it is possible to realize that the corrosion effect can be reduced, because the conditions harmful to the corrosion effect can be reduced. Due to the potential difference at the insulating sections of the supply lines, in the prior art, current may occur in the fluid guided through the respective supply line, in particular when the fluid is water. Thus, hydrogen and hydroxide ions may be released. By means of the invention, conditions important for the corrosive effect, i.e. in particular hydroxide ions, can be reduced. Preferably, the hydroxide ions can be at least partially treated or consumed in the cell stack by an electrolytic cell disposed there. Thus, hydroxide ions are no longer available for undesirable corrosive effects. It has therefore proved to be particularly advantageous if the insulating sections are arranged as close as possible in the region of the respective end. Thus, the present invention generally achieves: undesired corrosion effects are reduced or even completely avoided.

For example, the electrolytic cells can be arranged one after the other in a single cell stack. Preferably, the cells are electrically connected in series within the cell stack. The opposite ends of the cell stack, namely the first end and the second end, can be connected to the respective electrical potentials of the electrical energy source. For example, the end portion can be directly connected to the source of electrical energy. Preferably, however, the end is connected to a source of electrical energy via a control unit, so that the function of the electrolytic cell can be set as desired.

For example, the source of electrical energy can be any voltage source or also a current source capable of providing sufficient power for performing electrolysis by the electrolytic cell. The electrolysis power can be determined at a specific surface current density as a function of the dimensions of the respective electrolytic cell, in particular the area of the electrolytic cell that is electrolytically effective.

The supply line has a through opening with a suitable inner diameter or cross section in order to be able to conduct the respective operating substance to the electrolytic cell in a manner as lossless as possible and/or to be able to be conducted away from the respective electrolytic cell or sub-stack in a manner as lossless as possible.

According to one refinement, it is provided that the material of the supply line has metal, wherein the electrolytic cell is arranged in at least two sub-stacks, wherein each of the at least two sub-stacks is connected to the cell supply unit by means of at least one first supply line connected to a first end of the respective sub-stack and at least one second supply line connected to the cell supply unit and to a second end of the respective sub-stack opposite the first end in the stacking direction, wherein the first supply line connected to the first end of the sub-stack, which can be coupled to a negative potential of the electrical energy source, is connected to the cell supply unit in an electrically conductive manner, and all other supply lines have respective electrically insulating sections.

In this development, the cells of the partial stacks are preferably connected in series, wherein the respective partial stacks are also connected in series as a whole. In contrast, with regard to the connection to the cell supply unit, the sub-stacks are in principle connected essentially in fluid-technical parallel. The stack voltage at the respective opposite ends of the respective sub-stack can thus of course be significantly smaller than the voltage provided across the series connection by the electrical energy source. At the same time, the corrosion effects described at the outset can also be reduced or largely avoided here.

The electrically insulating sections of the supply lines are also formed in each case, which can be formed, for example, from a suitable material which can be mechanically firmly connected to the respective supply line. For example, it can be an annular section which is arranged at the respective end of the respective supply line. Furthermore, the insulation sections can of course also be integrated into the supply line, so that the supply line has two supply line sections which are electrically insulated from one another and are separated from one another by the insulation sections. The units thus formed are preferably connected to one another in a fluid-tight manner, wherein a substantially constant internal cross section is preferably provided for the respective operating substance.

For example plastics, ceramics and also oxides such as titanium dioxide, aluminum oxide, etc. can be provided as materials for the electrically insulating segments. Furthermore, it is also possible to provide a composite material, which can be formed, for example, from a plastic that can be reinforced, for example, with fibers. Of course, almost any combination thereof can also be provided, said combination being preferably selected such that chemical reactions with the respective operating substance to be guided are substantially avoided.

The material of the supply line has at least metal. For example, the metal can be steel, especially stainless steel. Further, of course, another metal such as titanium or the like can be used. Of course, corresponding metal alloys can also be provided.

According to one refinement, it is provided that an electrically insulating layer is provided on the inside of the supply line at the insulating section end of the respective insulating section facing the respective end of the respective sub-stack. The insulating layer formed here realizes: further reducing the corrosive effects. The electrically insulating layer can be formed, for example, from plastic, ceramic or the like, which is arranged on the inside in the respective supply line in the respectively predefined region. Thereby, the surface for corrosion effects can be further reduced inside the supply line.

It has proven to be particularly advantageous if the electrically insulating layer extends from the respective insulating section up to the respective end of the respective sub-stack. This makes it possible to avoid corrosion effects substantially completely on the supply line side. The improvement thus achieves the effect of further improving the present invention.

It is furthermore proposed that the electrically insulating layer has a coating made of an insulating material. The coating can be formed, for example, from plastic, paint, combinations thereof, and the like. The coating can be arranged on the inside in the region of the through openings of the supply lines before being installed at the respective supply lines. The coating need only extend as far as the electrically insulating sections. Thus, a good effect with regard to corrosion protection can be achieved with limited effort.

Furthermore, it is proposed that the electrically insulating layer has a corrosion-resistant metal-containing substance. A very robust surface can thereby be achieved, which can be well connected to the supply line.

Preferably, the corrosion resistant metal-containing material is a metal oxide. The metal oxide may be, for example, a ceramic material, titanium oxide, aluminum oxide, or the like.

According to one refinement, it is provided that the respective end of the sub-stack facing the respective insulation section is electrically insulated with respect to the electrolytic cell. This can be achieved: corrosion effects are largely avoided in the region between the insulating section and the respective end of the sub-stack. Thereby enabling the effect of the present invention to be further improved.

It is furthermore proposed that the cell supply unit is at least indirectly electrically grounded, i.e. that the cell supply unit can be connected to ground. The cell supply unit can be brought to a preset reference potential by grounding together with a supply line electrically coupled to the cell supply unit. In this way, the negative potential of the electrical energy source, which is electrically coupled to the cell supply unit via the supply line, can also be at least indirectly connected to ground. Thus, unlike in the prior art, the cell stack formed by the sub-stacks is at a defined potential with respect to ground potential, and is thus no longer subjected to a floating potential. Thus, a defined potential difference or voltage can thereby be achieved at the respective electrically insulating sections. This allows further improvement of the reliability of the function of the present invention.

It is furthermore proposed that the ground terminal has a sacrificial anode and/or a voltage source, by means of which the cell supply unit can be applied with a potential that is negative with respect to the ground potential. Thereby enabling "cathodic corrosion protection". If a voltage source is used, the negative potential of the voltage source can be electrically connected to the cell supply unit and to a supply line connected to said cell supply unit. The negative potential of the voltage source is preferably correspondingly grounded at the same time. In order to achieve a good function of corrosion protection in the manner described, it can be provided that the voltage source provides a voltage in the range of about-2V to about zero volts with respect to the ground potential. It has proven to be particularly advantageous if the voltage is selected in the range from about-1V to about-0.8V. Corrosion of e.g. stainless steel even under offshore conditions, especially in offshore applications, can be avoided by selecting voltages in said range. In particular, external corrosion phenomena can thereby be reduced or prevented.

In order to reduce or avoid internal corrosion phenomena as well, it can be provided that a further electrode of the counter electrode type for cathodic corrosion protection is provided in the region of the cell supply unit. The internal corrosion phenomena relate in particular to corrosion effects in the electrolysis device, in particular in the cell supply unit. For example, in this case, a titanium electrode or a titanium anode can be involved, which can be coated with a mixed oxide. Preferably, the anode formed in this way is disposed in the liquid phase of the oxygen separation vessel of the cell supply unit.

Particularly advantageously, the sub-stacks are connected in parallel in terms of supply to the cell supply unit. In this way, a good supply of at least one running substance can be achieved for the sub-stack. The supply can include the transport of the operating substance or substances generated during electrolysis as well as the export.

The feed structure formed in the sub-stack or the electrolytic cell can be used as an internal insulation section. In this case, the material contacting, for example, the water to be electrolyzed in the respective sub-stack (except in the region of the respective active cell face of the respective electrolytic cell) can fulfill at least one of the following three requirements: -the material is non-metallic;

the metal to which the potential is applied is coated with an oxidation-stable layer, such as titanium dioxide, polymers, etc.;

the uncoated metal is non-electrically bonded, i.e. bonded essentially without an electrical potential, in particular bonded floating.

That is, by the present invention, it can be achieved that the electrode of the active cell face of the electrolytic cell can be used as the counter electrode of the anode. Thereby, for example, more oxygen can be formed at a minimum at the respective anode of the electrolytic cell and less hydrogen can be formed at a minimum at the respective cathode of the respective electrolytic cell. However, the changes during electrolysis do not significantly affect the efficiency and safety of the electrolysis device. More precisely, the present invention has the advantage that, due to stray currents, no impurity ions can be released from the metal component.

If no sub-stacks are formed, the design and advantages given for the respective ones of the sub-stacks apply in principle (after corresponding adjustment) to the entire cell stack as well, of course.

The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and/or individually shown in the figures can be used not only in the respectively given combination but also in other combinations without departing from the scope of the invention.

The examples set forth below relate to preferred embodiments of the present invention. Features, feature combinations, and also features and feature combinations which are mentioned in the description of the embodiments below and/or which are shown individually in the drawings can be used not only in the respectively given combination but also in other combinations. Embodiments of the invention which are not explicitly shown and described in the figures, but which are known and can be produced from the described embodiments by means of separate feature combinations, are therefore also included or are to be regarded as disclosure. The features, functions and/or actions illustrated in accordance with the embodiments can themselves each illustrate a separate, what can be considered to be independent of each other, which in turn each improves the invention independently of each other. Thus, the examples should also include combinations different from those in the illustrated embodiments. Furthermore, the described embodiments can be supplemented by other features, functions, and/or actions of the invention, which have been described.

Drawings

In the drawings, like reference numerals designate like features or functions.

The drawings show:

FIG. 1 shows in a schematic block diagram an electrolysis device for electrolysis of water;

fig. 2 shows a schematic cross-section of the supply line of the electrolysis device according to fig. 1 in the region of the insulation section;

FIG. 3 shows a schematic block diagram of another electrolysis device for electrolysis of water, as in FIG. 1, in which the cell stack is divided into four sub-stacks according to a first design; and

fig. 4 shows a second embodiment of the electrolysis device, as in fig. 3.

Detailed Description

Fig. 1 shows an electrolysis device 10 in a schematic block diagram, having a cell stack 54 with a plurality of electrolysis cells 12 arranged one after the other in a stacking direction 14. The electrolytic cell 12 is currently used to electrochemically split water into its constituent parts, namely hydrogen and oxygen. Thus, the electrolyzer 10 is currently used to produce hydrogen and oxygen from water.

The electrolytic cells 12 are currently arranged directly adjacent to each other such that the respective electrodes of the adjacently arranged electrolytic cells 12 can be electrically contacted. It is proposed here that the anodes of a first one of the electrolytic cells 12 each electrically contact the cathodes of a second electrolytic cell 12 each arranged directly adjacent thereto. Thus, the electrolytic cells 12 are electrically connected in series.

Via an internal supply structure, not shown further, of the cell stack 54, the electrolytic cells 12 are supplied on the one hand with water to be electrolyzed and on the other hand with lead-out for the produced substances, i.e. hydrogen and oxygen. The supply devices are configured to be connectable to the respective opposite ends 20, 22 of the cell stack 54.

Furthermore, an electrical energy source 16 is connected via an electrical line 52 to the ends 20, 22, which currently provides a suitable voltage and a suitable electrical power, so that the electrolytic cell 12 can be sufficiently supplied with electrical energy for normal operation.

The electrolysis device 10 further comprises a cell supply unit 18 for supplying the electrolysis cell 12 or the cell stack 54 with the respective operating substances, which supply currently involves the transport of water and the export of hydrogen and oxygen. The cell supply unit 18 comprises a number of components, such as pumps, heat exchangers, separation vessels, etc., which are required for the conventional operation of the electrolysis device 10, which components are not further shown here. The cell supply unit 18 is connected in supply with the cell stack 54 via supply lines 24 connected to opposite ends 20, 22 on the cell supply unit 18 and the cell stack 54. Thus, the supply line 24 fluidly couples the supply structure of the cell stack 54. The supply line 24 is currently formed of metal, such as stainless steel.

In order to avoid a short circuit between the ends 20, 22 of the cell stack 54 by the supply lines 24 being formed of metal, each of the supply lines 24 has an electrically insulating section 38. Thereby ensuring that: the ends 20, 22 are electrically insulated from the cell supply unit 18 and thus also from each other. The supply line 24 is outside of the cell stack 54.

The insulating section 38 is now essentially formed from an electrically insulating material, which can be, for example, a suitable ceramic material, or can also be a suitable plastic or composite material.

Fig. 2 shows a schematic sectional view of one of the supply lines 24 from fig. 1 in the region of the insulation section 38. In fig. 2, the supply line 24 is shown with a first region 58 facing the end 22 of the cell stack 54, while an opposite second region 56 faces the cell supply unit 18. Regions 56 and 58 are electrically separated from each other by insulating section 38. The arrangement is generally fluid-tight and has a substantially constant inner diameter 62 through which a corresponding fluid, in this case water, can be directed.

Corrosion occurs in region 64 due to the voltage applied to electrically insulating segment 38. This can be considered to be due to: in the region of the transition from region 56 to electrically insulating section 38, negative hydroxide ions are formed by electron absorption from the metal of the wall of supply line 24 into the water flowing in inner diameter 62, which negative hydroxide ions are guided by the electric field toward region 58 and react electrochemically there with the metal of the wall of supply line 24, as is shown in fig. 2. Thereby, the wall of the supply line 24 erodes in the region 64. This is undesirable.

For corrosion of this type, it is to be considered that a direct voltage in the range of several hundred volts can be applied over the area of the electrically insulating section 38, typically in normal operation. As a result, an electron excess can occur in the region 56 and an electron deficiency can occur in the region 58 in the region of the electrically insulating section 38. Due to the magnitude of the voltage at the electrically insulating section 38, from a thermodynamic point of view, an electrode reaction as set forth above occurs. Although the corrosion effect can be stretched in time, i.e. kinetically suppressed, by lowering the voltage, it cannot be completely suppressed thereby. Extending the insulating section or reducing the inner diameter 62 by means of the electrically insulating section 38 can also suppress corrosion effects only in terms of its effect, but corrosion effects cannot be avoided.

In the region 56, the hydrogen gas formed in this case can be dissolved in the water or can also be present in the form of the finest bubbles and carried away with the water. The amount produced is generally small here, so that the hydrogen itself does not have a disturbing effect.

However, this is not applicable with respect to hydroxide ions present in dissolved form in water. The hydroxide ions tend to move from region 56 to region 58 due to the negative charge of the hydroxide ions and the direction of the electric field in the region of electrically insulating section 38. Then, in said zone 58, the metallic material of the supply line 24 is decomposed in an oxidizing manner. The decomposition is shown in fig. 2 for the following case: the supply line 24 is formed of stainless steel. However, the effect is not limited to steel, but can occur in almost any other arbitrary metallic material.

But in addition to releasing iron, other metals that can be present in the steel can also be dissolved. In which case cations can be formed. Due to its positive charge, the metal cation has a tendency to move in the opposite direction to the hydroxide ion. This may result in: so-called rust (Rouging) is generated by metal cations, especially when it is an iron ion, and hydroxide ions. Rust means the finest iron-containing particles that can be distributed in the feed line 24 and the components of the electrolysis device 10. The particles can be observed mainly in the supply line 24, which also leads to hydrogen. If the rust reaches the oxygen-directing portion of the electrolyzer 10, the rust can redissolve to form ions.

The cations can then in particular come out of the oxygen side into the electrolytic cell 12 and accumulate there. The process can result in a higher cell voltage of the electrolyzer 10 and thus reduced efficiency. Furthermore, the detrimental mechanism of the electrolytic cell 12 may be related to the cations. For example, hydrogen peroxide formed at the electrodes can be converted into radicals upon contact with metal ions, which can chemically act on the membrane structure of the electrolytic cell 12, thereby compromising the useful life of the electrolytic cell 12.

Fig. 3 now shows an electrolysis device 60, by means of which the above-described corrosion effects described with reference to fig. 2 can be largely avoided. The following description is based on the description of fig. 1 and 2, and thus additionally references embodiments related thereto.

As can be seen from fig. 3, the electrolytic cells 12 are arranged in four sub-stacks 26, 28, 30, 32. Each of the four sub-stacks 26, 28, 30, 32 is connected to the cell supply unit 18 by means of two first supply lines 24 connected to the cell supply unit 18 and to a first end of the respective sub-stack 26, 28, 30, 32 and two second supply lines 24 connected to the cell supply unit 18 and to a second end 22 of the respective sub-stack 26, 28, 30, 32 opposite the first end 20 in the stacking direction 14. For the cell supply unit 18, the embodiments with respect to fig. 1 and 2 are basically applicable.

The first supply line 24 connected to the first end 20 of the sub-stack 26 coupled to the negative potential 34 of the electrical energy source 60 is electrically conductively connected to the cell supply unit 18. Thus, just the first end 20 of the sub-stack 26 is directly electrically connected to the cell supply unit 18. All other supply lines 24 have corresponding electrically insulating sections 38.

It is currently proposed that the number of cells 12 of the sub-stacks 26, 28, 30, 32 is the same for all sub-stacks 26, 28, 30, 32. However, this can also be chosen differently in other designs, as desired, without departing from the basic idea of the invention.

The sub-stacks 26, 28, 30, 32 are electrically connected in series with respect thereto, so that (from an electrical point of view) there is in turn a series connection of all the cells 12 of the sub-stacks 26, 28, 30, 32 (as in the cell stack 54 according to fig. 1).

By means of the described construction of the electrolysis device 60 it is possible to realize that the cell supply unit 18 is electrically observed to have a minimum potential of the entire electrolysis device 60. The potential is also connected to a negative potential 34 of the source of electrical energy 16. In addition, the electrical energy source 16 provides a positive potential 36. Between negative potential 34 and positive potential 36, electrical energy source 16 provides an operating voltage for conventional operation of electrolyzer 60.

In the present embodiment, it is also proposed that an electrical insulation layer is formed on the inside of the supply line at the insulation section end 40 of the respective insulation section 38 facing the respective end 20, 22 of the respective sub-stack 26, 28, 30, 32, said electrical insulation layer currently being formed by a coating made of an insulating material. For example, the insulating material is a suitable plastic. Alternatively or additionally, however, corrosion-resistant metal-containing materials, such as metal oxides or the like, in particular, for example, ceramic materials, can also be provided.

Furthermore, it can also be provided that the respective end 20, 22 of the sub-stack 26, 28, 30, 32 facing the respective insulation section 38 is electrically insulated from the electrolytic cell 12. Whereby the corrosive effects can be further reduced. It has proven to be particularly advantageous if, as is currently shown in fig. 3, the cell supply unit 18 is electrically grounded by means of a grounding terminal 42.

The improvement according to fig. 4 is particularly advantageously proposed. Fig. 4 shows a variant of the electrolysis device 60 according to fig. 3 in a schematic illustration as in fig. 3, only the differences with respect to the design according to fig. 3 being explained below.

In fig. 4 it is proposed that the ground 42 is not provided directly at the cell supply unit 18, but that the cell supply unit 18 is applied with a potential that is negative with respect to the ground potential by means of a voltage source 44. For this purpose, the voltage source 44 provides a voltage of about-1V to about-0.8V. In principle, however, the voltage can also be selected in the range of, for example, about-2V to about zero volts.

The voltage thus set makes it possible to suppress corrosion effects even in offshore conditions, for example in offshore applications, for example in the case of stainless steel, in order to prevent corrosion.

It has proven to be particularly advantageous if the counter electrode for cathodic corrosion protection is then also arranged in the region of the cell supply unit 18. The electrode provided here for the ground terminal 42 is currently formed by a titanium anode coated with a mixed oxide. The titanium anode with the mixed oxide coating is currently arranged in the liquid phase of an oxygen separation vessel, not further shown, electrically isolated from the cell supply unit 18.

The embodiments generally show that by means of the invention can be achieved: corrosion can be reduced by way of a plurality of sub-stacks 26, 28, 30, 32 capable of forming the electrolytic cell 12, which continue all to be connected electrically in series, yet are connected individually to the cell supply unit 18 via their own supply lines 24.

By the ground terminal concept or the ground wire concept of the present invention, the release of metal ions can be prevented to a great extent. Thus, the electrode of the active cell face of the electrolytic cell 12 can act as the counter electrode of the anode for stray currents. Thus, undesirable corrosion can be avoided to a large extent.

The invention is not limited to application in the electrolysis of water and can equally well be used in other electrolysis to be performed, such as carbon dioxide electrolysis or the like.

The examples are only for illustration of the invention and should not be limiting thereof.

Claims

1. An electrolysis apparatus (60) having:

a plurality of electrolytic cells (12) which are electrically connected in series and which are arranged one after the other at least partially in the stacking direction (14), wherein the series connection is electrically couplable to an electrical energy source (16),

-a cell supply unit (18) for supplying the electrolytic cell (12) with at least one operating substance for normal operation, and

-a supply line (24) connected to the cell supply unit (18) and to opposite ends (20, 22) of the electrolytic cells (12) arranged one after the other,

it is characterized in that the method comprises the steps of,

the negative potential (34) of the electrical energy source (16) can be electrically coupled to a reference potential of the cell supply unit (18).

2. The electrolysis device according to claim 1, wherein the material of the supply line (24) has metal, wherein the electrolysis cell (12) is arranged in at least two sub-stacks (26, 28, 30, 32), wherein each of the at least two sub-stacks (26, 28, 30, 32) is connected to the cell supply unit (18) by means of at least one first supply line (24) connected to the cell supply unit (18) and connected to a first end (20) of the respective sub-stack (26, 28, 30, 32) and at least one second supply line (24) connected to the cell supply unit (18) and connected to a second end (22) of the respective sub-stack (26, 28, 30, 32) opposite the first end (20) in the stacking direction (14), wherein the first end (24) of the sub-stack (26) coupled to the potential (34) of the electrical energy source (16) has an electrically conductive connection to the respective supply line (38) of the other electrically conductive segments.

3. An electrolysis device according to claim 2, wherein an electrically insulating layer is provided inside the supply line at the insulating section end (40) of the respective end (20, 22) of the respective insulating section (38) facing the respective sub-stack (26, 28, 30, 32).

4. An electrolysis device according to claim 3, wherein the electrically insulating layers extend from the respective insulating sections (38) up to the respective ends (20, 22) of the respective sub-stacks (26, 28, 30, 32).

5. An electrolysis device according to claim 3 or 4, wherein the electrically insulating layer has a coating of insulating material.

6. An electrolysis device according to any one of claims 3 to 5, wherein the electrically insulating layer has a corrosion resistant metal containing material.

7. The electrolysis device according to any of the preceding claims, wherein the respective end (20, 22) of the sub-stack (26, 28, 30, 32) facing the respective insulation section (38) is electrically insulated from the electrolysis cell (12).

8. The electrolysis device according to any of the preceding claims, wherein the cell supply unit (18) is at least indirectly electrically connectable (42) to a ground terminal (42).

9. The electrolysis device according to claim 8, wherein the ground (42) has a sacrificial anode and/or a voltage source (44) by means of which the cell supply unit (18) can be applied with an electric potential that is negative with respect to the ground potential (42).

10. The electrolysis device according to any one of claims 2 to 9, wherein the sub-stacks (26, 28, 30, 32) are connected in parallel in terms of supply to the cell supply unit (18).