WO2024008549A2

WO2024008549A2 - Operation of an electrolysis device having a plurality of electrolysis cells

Info

Publication number: WO2024008549A2
Application number: PCT/EP2023/067832
Authority: WO
Inventors: Sven Schumann; Marvin Bendig; Markus Engel
Original assignee: Siemens Energy Global GmbH & Co. KG
Priority date: 2022-07-06
Filing date: 2023-06-29
Publication date: 2024-01-11
Also published as: DE102022206878A1; WO2024008549A3

Abstract

The invention relates to a support device (90) for an electrolysis device (10) having a plurality of electrolysis cells (12), comprising connection contacts (72) for electrical coupling to respective electrodes of the electrolysis cells (12). According to the invention, the support device (90) has at least one voltage detection unit for detecting a cell voltage of each of the electrolysis cells (12) and an evaluation unit (18), which is coupled in terms of signal technology to the at least one voltage detection unit, for determining at least one cell characteristic or at least one state of health for each of the electrolysis cells (12), and a number of controllable electronic current source circuits (42) corresponding to the plurality of electrolysis cells (12), wherein each of the current source circuits (42) is electrically coupled to electrodes of each of the electrolysis cells (12) and is designed to supply the respective electrolysis cell (12) individually with a direct current that can be adjusted depending on a current source control signal.

Description

Operating an electrolysis device having a plurality of electrolysis cells

The invention relates to a support device for an electrolysis device having a plurality of electrolysis cells, with connection contacts for electrical coupling to respective electrodes of the electrolysis cells. The invention further relates to an electrolysis device with a plurality of electrolysis cells. Finally, the invention relates to a method for operating an electrolysis device having a plurality of electrolysis cells, wherein respective electrodes of the electrolysis cells are electrically coupled to connection contacts of the support device for electrical coupling with a support device for the electrolysis device.

Electrolysis devices, support devices for them and methods for operating electrolysis devices are extensively known in the prior art, so that there is basically no need for separate printed evidence for this. Generic electrolysis cells and electrolysis devices, in particular for the electrolysis of water to hydrogen and oxygen, are extensively known in the prior art, for example from DE 197 29 429 CI. The basic function of electrolysis, in particular water electrolysis, is known to those skilled in the art, which is why detailed explanations are not provided here.

Electrolysis devices, which have a single, but in particular a large number of electrolysis cells, which are usually at least partially electrically connected in series, serve, among other things, to produce substances which can preferably be used on an industrial scale, for example hydrogen in water electrolysis, carbon monoxide in carbon dioxide electrolysis. to produce electrolysis or the like. To this end During normal operation, at least two electrodes of a respective electrolytic cell are supplied with a suitable small electrical direct voltage, which can be in the range of a few volts or possibly even less than 1 V. Depending on the amount of material to be provided by the electrolysis, an electrolysis energy source provides a corresponding electrical direct current as electrolysis current. When electrolysis cells are connected in series, this direct current flows through all of the battery cells connected in series. The series connection is electrically coupled to an electrolysis energy source. Basically, however, it is also possible to connect electrolytic cells not only in series, but also at least partially in parallel.

In particular in aqueous electrolysis, such as chlorine/alkali electrolysis, PEM electrolysis or the like, a membrane is often provided which separates respective reaction chambers of respective reaction areas of a respective electrolysis cell, in which respective electrodes are arranged. A catalyst is often arranged on such a membrane to enable or catalytically accelerate the electrolysis process. The electrolysis is usually brought about by the fact that the electrodes of a respective electrolysis cell are subjected to the electrolysis current or a suitable electrical direct voltage, also called cell voltage, during normal operation.

What proves to be at least partially critical for a respective electrolysis cell is, among other things, a transition from or to an operating state that is different from the intended operating state. This refers in particular to starting up the electrolysis cell or the electrolysis device as well as shutting down the electrolysis cell or the electrolysis device. Particularly when shutting down after normal operation, residues, especially dissolved or gaseous residues, can still form. se, be present in the electrolytic cell, which under certain circumstances can lead to the electrolytic cell being able to display fuel cell functionality. However, this can cause irreversible damage to the electrolytic cell, which is why the fuel cell functionality should be avoided at all costs. For this purpose, it is known to apply a protective voltage, also called polarization voltage, to the electrolytic cell outside of normal operation, which is selected so that the fuel cell functionality can be largely avoided. For example, in an electrolytic cell for electrolyzing water, the protection voltage can be approximately 1.25 V. As soon as the electrolysis cell has cooled down accordingly and residual gases have been removed, the provision of the protective voltage can be deactivated.

Generic support devices serve, among other things, to support or be able to achieve safe operation of the electrolysis cells, in particular the electrolysis device. For this purpose, the electrolysis cells are electrically connected to the support device, so that the electrolysis cells can be supplied with a polarization current independently of one another. Such a device is disclosed, for example, in EP 3 982 501 Al.

Furthermore, it has been shown that electrolysis cells age differently from one another and/or can have different characteristics. This can prove particularly problematic when electrolytic cells are connected in series if a protective voltage is to be provided as a polarization voltage by a voltage applied to the series connection. Due to the different aging or characteristics, it can happen that, particularly when the electrolytic cells are connected in series, the voltage applied to the series connection is not evenly distributed among all electrolytic cells connected in series. Hence it is then It is necessary to choose the electrical voltage of the series connection so high that the protective voltage can still be reliably achieved for the most unfavorable electrolytic cell. However, this means that the other cells are subjected to a correspondingly high voltage, which can be significantly greater than the protective voltage, so that they continue to be operated in electrolysis mode. To avoid an explosive mixture in these electrolysis cells, it is therefore common practice to flush with nitrogen.

It is also known from EP 3 982 501 A1 to apply the protective voltage to each electrolysis cell individually. However, providing the respective protective voltages for the electrolytic cells proves to be comparatively complex. In addition, no aging condition or characteristics of the electrolytic cells are taken into account here, so undesirable conditions can still occur.

The invention is based on the object of enabling improved operation of the electrolysis cells and the electrolysis device and of specifying a corresponding method.

With regard to a generic support device, the invention in particular proposes that the support device has at least one voltage detection unit for detecting a cell voltage of a respective electrolytic cell, as well as an evaluation unit, which is coupled in terms of signals to the at least one voltage detection unit, for determining at least one cell characteristic or at least one aging state for one each of the electrolysis cells, wherein a number of controllable electronic power source circuits corresponding to the plurality of electrolysis cells is provided, wherein a respective one of the current source circuits is electrically coupled to electrodes of a respective one of the electrolysis cells and is designed to provide the respective electrolysis cell to be individually supplied with a direct current, which can be adjusted depending on a current source control signal.

With regard to a generic electrolysis device, the invention particularly proposes that the electrolysis device has a support device according to the invention.

With regard to a generic method, the invention in particular proposes that cell voltages of the electrolysis cells be detected by means of at least one voltage detection unit of the support device that is electrically coupled to the connection contacts, the voltage detection unit providing a respective voltage signal depending on the electrical voltage detected in each case, the voltage signals be evaluated by means of an evaluation unit in order to determine at least one cell characteristic or at least one aging condition for a respective electrolytic cell.

The invention is based, among other things, on the idea of detecting the cell voltages of the individual electrolytic cells, especially when the electrolytic cells are connected in series, and evaluating them using the evaluation unit. The evaluation unit can then determine at least one cell characteristic or at least one aging state based on this data. For this purpose, it can be taken into account, for example, which cell current is or was applied to each of the electrolysis cells. Of course, both the cell characteristics and the aging condition of the respective electrolytic cell can also be determined. This data can be used to operate the electrolytic cells better individually, for example by individually setting a cell current, so that the electrolytic cells can be operated individually as best as possible in their most favorable operating state. This can be done in particular for proper electrolysis operation, starting up the electrolysis device and/or be provided for shutting down the electrolysis device. In addition, it can be achieved that, for example, for a higher-level electrolysis control of the electrolysis device, data is provided that allows the load capacity of the respective electrolysis cell to be recognized. This resilience, which can also include the aging condition, can be used to be able to adjust the performance of the electrolytic cell within a predetermined operating range. This can be used, for example, to vary or adjust an electrolysis output of the electrolysis device or the like.

For example, if a low electrolysis output is to be activated, it is advantageous to operate the electrolysis cells with an unfavorable aging condition, if possible, whereas if a high electrolysis output is desired, it is preferable to activate electrolysis cells with a low aging condition, that is, preferably essentially new electrolysis cells . Of course, it can also be provided that through the intended operation of the electrolytic cells and respective activation or deactivation of the electrolytic cells it can be achieved that different aging conditions of the electrolytic cells can be equalized. Among other things, the knowledge that a cell voltage can arise at a given cell current depending on the aging condition is used. For a given cell current, the cell voltage generally increases as the cell ages. The aging condition of the electrolytic cell can therefore be determined, for example, based on the operating parameters of the electrolytic cell. Operating parameters can be, for example, the cell voltage, a cell current, a temperature of the electrolytic cell, values of fluid flows such as liquids and/or gases or the like.

In addition, it can be taken into account that the cell voltage also depends, among other things, on the activation of catalysts and can be dependent on the like. Preferably, with the assistance of the support device, improved operation of the electrolysis cells of the electrolysis device and thus also of the electrolysis device as a whole can be achieved.

At the same time, the support device of the invention makes it possible to start up or shut down the electrolysis device in a safer and more reliable manner overall. This can be achieved, among other things, by detecting the respective cell voltages of the electrolytic cells during normal operation and/or during startup or shutdown and taking them into account for setting a respective cell current. The respective cell current can preferably also be taken into account. This is preferably done depending on the determined cell characteristics or the determined aging state. The cell characteristics can include, for example, an individual characteristic curve, possibly further cell parameters and/or the like of a respective electrolysis cell.

The support device has respective connection contacts for connecting to the electrolysis device, in particular for connecting to the electrolysis cells in the form of electrical coupling, so that the desired electrical connection can be established with the electrodes of the electrolysis cells. The support device also has the voltage detection unit, which is used to detect the cell voltages of the electrolytic cells. For this purpose, the voltage detection unit is preferably electrically coupled to the connection contacts of the support device. The voltage detection unit can, for example, detect the respective cell voltages individually or in a time multiplex. The voltage detection unit provides corresponding voltage signals that are transmitted to the signal-coupled evaluation unit. The corresponding voltage signals are therefore available for evaluation. teunit is available so that it can at least determine the cell characteristics or at least the aging condition of the respective electrolytic cell. The support device, in particular the voltage detection unit and possibly also the evaluation unit, can be designed as an electronic hardware circuit. However, they can also be formed at least partially by a program-controlled computer unit. Of course, combinations of these can also be provided.

The invention proves to be particularly advantageous when the electrolysis cells of the electrolysis device are at least partially connected in series. However, the invention is not limited to this. The support device can therefore also be intended to be used in an electrolysis device which has electrolysis cells at least partially connected in parallel. Of course, combinations of series connections and parallel connections of electrolytic cells can also be provided.

According to a further development, it is proposed that the voltage detection unit has a number of voltage sensors corresponding to the plurality of electrolytic cells, wherein each of the voltage sensors is electrically coupled to electrodes of a respective electrolytic cell and is designed to detect a cell voltage of the respective electrolytic cell and depending on the to emit a respective voltage signal from the detected cell voltage. The voltage detection unit can therefore simultaneously detect the cell voltages of the majority of electrolysis cells and emit corresponding voltage signals. This allows very fast signal processing to be achieved. Overall, the support device can be improved and, if necessary, the function can also be improved.

In addition, it is proposed that the support device has at least one current sensor for detecting a cell current from at least one of the electrolysis cells and for emitting a current signal depending on the detected cell current. If the electrolysis cells are connected in series, a single current sensor can usually be sufficient. However, it can also be provided that a respective individual current sensor for detecting the cell current is preferably provided for each of the electrolysis cells. By means of the current sensor, the cell current can preferably be detected at least during the intended electrolysis operation or outside of the intended electrolysis operation, for example also the polarization current when shutting down the electrolysis device. The current sensor is preferably also signal-coupled to the evaluation unit, so that the current signals can be transmitted to the evaluation unit. The evaluation unit can then also take the at least one current signal into account when evaluating.

It is further proposed that the support device has a number of controllable electronic power source circuits corresponding to the plurality of electrolytic cells, each of the current source circuits being electrically coupled to electrodes of a respective electrolytic cell and being designed to apply a direct current to the respective electrolytic cell individually , which is adjustable depending on a power source control signal. This makes it possible for each of the majority of electrolysis cells to be individually supplied with a corresponding direct current. This proves to be particularly advantageous if the electrolysis device or the electrolysis cells are operated outside of the intended electrolysis operation, in that the electrolysis cells are preferably supplied with a protective current or polarization current, for example to suppress or avoid the undesirable fuel cell functionality. This is particularly the case when starting up the electrolysis device or when shutting down the electrolysis device, in which electrical systems connected in series Rolysis cells can otherwise be electrically applied unevenly. With the individually provided power source circuits, each of the electrolysis cells can be individually supplied with the electrical cell current. This cell current can, for example, be the protective current to prevent fuel cell functionality. The protective current is preferably dependent on the determined cell characteristics and/or the determined aging condition.

Each of the power source circuits is adjustable using the power source control signal. The power source control signal can be provided for one or more of the power source circuits, for example by the evaluation unit but also by the higher-level electrolysis control of the electrolysis device. This makes it possible to operate each of the electrolysis cells in an optimal operating state.

Furthermore, it is proposed that the evaluation unit is designed to record the cell voltage and the cell current over a predeterminable period of time and, depending on this, to determine the cell characteristics and/or the aging state of the electrolytic cell. The cell current can preferably be recorded at least during the intended electrolysis operation or at least outside of the intended electrolysis operation. However, the cell current can also be recorded essentially permanently, particularly advantageously. For this purpose, it can be provided that the evaluation unit has data from a new electrolytic cell as reference or starting values, or retrieves these as a data record from an external data memory via a communication connection. Using the respective power source circuit, it is even possible to currently record and save an individual characteristic curve for each of the electrolysis cells. In this way, for example, the cell characteristics can also be determined for an unknown electrolysis cell. This data can be used to further To be able to determine a change in the respective cell characteristics, in particular the operational aging state, of the respective electrolytic cell. Among other things, the cell characteristics can also include operating states, operating state changes, operating parameters and/or operating parameter changes that can be determined for the electrolysis cells. Of course, it can also be provided that data relating to a state in relation to an end of use of the electrolytic cells is stored in a retrievable manner, with the evaluation unit being able to determine whether a respective one of the electrolytic cells has reached the end of use. Once the end of use has been reached, the evaluation unit can, for example, emit a signal that the respective electrolytic cell should be serviced or replaced. As a result, the function of the electrolysis device as a whole can be further improved. At the same time, the determined aging states of the electrolytic cells can be used to provide individual power source control signals depending thereon, so that the electrolytic cells can be supplied with the cell current, preferably depending on their respective determined aging state. This also enables a further improvement in the operation of the electrolysis device overall.

It proves to be particularly advantageous if the evaluation unit is designed to determine cell characteristics and/or aging states of all electrolysis cells coupled to the support device and, depending on the determined aging states, to determine control data for an operating state in electrolysis operation, starting up and/or shutting down the electrolysis device. This control data can, among other things, also have data relating to the power source control signals, so that the optimal possible operation of the electrolysis cells can be achieved, especially when starting up or shutting down the electrolysis device, especially if they are connected in series. It is further proposed that the support device has a separately manageable housing which has a plug connector for electrically connecting the support device to the electrolysis cells. This makes it possible to easily connect the support device to the electrolysis cells, in particular to the electrolysis device, and to establish reliable electrical contact. The separately handleable housing can be a closed housing, so that the support device is reliably protected from external influences. This is particularly advantageous if dangerous substances can occur in the environment of the support device, for example an explosive gas mixture, an aggressive atmosphere and/or the like. The connection contacts are preferably also arranged on the housing so that they can be contacted electrically.

According to a further embodiment, it is proposed that the evaluation unit is designed to determine operating states of all electrolysis cells coupled to the evaluation unit and, depending on the determined operating states, to provide a status signal for a higher-level electrolysis control in order to control the cell current depending on the status signal. The status signal can be used to adjust the individual power source control signals. However, it can also be used to control the cell current that is to be provided by the higher-level electrolysis control during normal electrolysis operation. In this way, overloading of individual electrolytic cells, particularly severely aged electrolytic cells, can be avoided. It can thus be achieved, for example, that the cell current can be controlled in a suitable manner at least during the intended electrolysis operation or at least outside the intended electrolysis operation during the protective operation. Furthermore, the electrolysis cells can also be operated outside of a permissible intended electrolysis operation, which can be achieved, for example, by a cell design and/or Bernes Solution parameters can be determined can be avoided. Overall, the reliability of the operation of the electrolysis device and the operational lifespan can be further improved or increased.

The support device preferably has a communication interface with which it is in communication connection with the higher-level electrolysis control of the electrolysis device. The communication interface can be designed for wireless or wired communication.

The support device can also be designed to record further operating parameters of the electrolysis cells, preferably on a cell-specific basis. For this purpose, the support device can have suitable parameter sensors, which can be arranged at least partially integrated in the support device or also in the respective electrolysis cells. Such parameter sensors can be used, for example, to detect a temperature in the electrolysis cells or their cell membranes or process fluids and gases, to detect a flow rate of process fluids in the respective electrolysis cell, in particular with regard to electrolysis cells for the electrolysis of water, a water vapor measurement, a gas composition , for example to determine whether a gas composition contains an ignitable mixture, to record a pressure measurement and / or the like. Preferably, these parameter sensors can also be coupled to the evaluation unit in terms of signals, so that the evaluation unit can carry out the evaluation additionally depending on these signals. Here too, a further improvement in the operation of the electrolysis device can be achieved.

In the method according to the invention for operating a plurality of electrolysis cells, a respective one of the power source circuits of the support device is advantageously connected to electrodes of a respective one of the electrolysis cells. len electrically coupled, with the respective electrolytic cell being individually supplied with a direct current that is set depending on a power source control signal.

Both protective operation and normal operation of a plurality of electrolytic cells can therefore be carried out on a cell-by-cell basis using the support device. At the same time, for example, the determined aging states of the electrolysis cells can be used to provide individual power source control signals depending on this, so that the electrolysis cells are supplied with the cell current, preferably depending on their respective determined aging state. Depending on the operating mode, a protective current is supplied to a respective electrolysis cell in protective operation or an operating current for normal electrolysis operation in normal operation.

The advantages and effects specified for the support device according to the invention naturally also apply equally to the electrolysis device according to the invention and the method according to the invention and vice versa. In this respect, device features can also be formulated as process features and vice versa.

The exemplary embodiments explained below are preferred embodiments of the invention. The features and feature combinations specified previously in the description as well as the features and feature combinations mentioned in the following description of exemplary embodiments and/or shown alone in the figures are not only in the combination specified in each case, but also in others Combinations can be used. Embodiments of the invention are therefore also included or are to be regarded as disclosed, which are not explicitly shown and explained in the figures, but which emerge from the explained embodiments and can be generated by separate combinations of features. The features, functions and/or effects shown using the exemplary embodiments taken individually, each of which can represent individual features, functions and/or effects of the invention that are to be considered independently of one another and which also further develop the invention independently of one another. Therefore, the exemplary embodiments should also include combinations other than those in the explained embodiments. In addition, the described embodiments can also be supplemented by further features, functions and/or effects of the invention that have already been described.

In the figures, the same reference numbers designate the same features and functions.

Show it:

1 shows a schematic circuit diagram of an electrolysis device with a plurality of electrolysis cells connected in series, which are connected to an electrolysis energy source and an auxiliary energy source connected in parallel thereto;

2 shows a schematic diagram of a polarization characteristic curve for an electrolysis cell of the electrolysis device according to FIG. 1, in which a cell voltage of the electrolysis cell is shown as a function of an electrolysis current of the electrolysis cell;

3 shows a schematic circuit diagram like FIG. 1, an electrolysis device in which a protective unit is connected in parallel to each individual electrolysis cell;

4 shows a schematic diagram representation in which a clocked current is shown as a protective current for an electrolytic cell according to FIG. 1 as well as a cell voltage and a control signal for the protective current using respective graphs, 5 shows a schematic diagram representation of an oscillogram of a further protective current,

6 shows a schematic diagram representation of an aging of the electrolytic cell subjected to the protective current according to FIG. 5, determined based on polarization characteristics,

7 shows a schematic block diagram representation of a protection unit according to FIG. 3,

8 shows a schematic block diagram of a structure of the electrolysis device with the support device,

9 shows a schematic perspective view of a first embodiment of an arrangement of the support device on an electrolysis device designed as a module, and

10 in a schematic representation like FIG. 9 shows a second embodiment of an arrangement of the support device on an electrolysis device designed as a module.

1 shows a schematic circuit diagram representation of an electrolysis device 52 with a plurality of electrolysis cells 12 electrically connected in series. In the present case, the electrolysis cells 12 are used for the electrolysis of water to hydrogen and oxygen in a reaction space, not shown, which is formed between the respective electrodes of the respective electrolysis cell 12. In alternative embodiments, another substance can of course also be subjected to electrolysis as a starting material in order to convert it into corresponding other substances as a product. The series-connected electrolysis cells 12 are connected to a main rectifier 14 as an electrolysis energy source. The main rectifier 14 provides an operating voltage 50 with which the series connection of the electrolysis cells 12 is applied, so that in normal operation, namely electrolysis operation, an electrolysis current 48 flows through the electrolysis cells 12.

In parallel to the main rectifier 14, a series circuit consisting of a polarization rectifier 54 and a protective inductor 58 as an auxiliary energy source is connected to the series circuit of the electrolytic cells 12. The polarization rectifier 54 and the protective inductance 58 serve to apply a rectifier voltage 68 to the electrolysis cells 12 outside of the intended electrolysis operation, which is selected so that a protective current 56 is established, which in turn is selected so large that all electrolysis cells 12 have at least one Sufficiently large polarization voltage Uo (FIG 2), which is set greater than or equal to a required protection voltage U _s , are applied. This is intended to avoid undesirable processes in the electrolysis cells 12 outside of the intended electrolysis operation.

2 shows a diagram 60 in a schematic diagram representation, in which an ordinate 62 of a cell voltage at respective cell connections 28 is assigned to an individual electrolytic cell 12. An abscissa 64 is assigned to the corresponding cell current of this electrolysis cell 12. The dependence of the cell voltage on the cell current is shown as a polarization characteristic curve with a graph 66. U _N denotes an electrolysis voltage that occurs at the electrolysis cell 12 in normal electrolysis operation when the electrolysis cell 12 is subjected to the electrolysis current 48 of an electrolysis current I _n . An intersection of the graph 66 with the ordinate 62 defines the polarization voltage Uo, below which can result in a polarization change of the cell current. In the present embodiment of the electrolysis cell 12 for the electrolysis of water, the electrolysis voltage U _N is approximately 1.8 to 1.9 V. The polarization voltage Uo can be approximately 1.48 V in the present embodiment. Depending on a design of the electrolysis cells 12, the polarization voltage Uo can also be in a range from approximately 1.25 V to approximately 1.45 V. At a cell voltage that is greater than approximately 1.48 V, electrolysis functionality begins in the electrolysis cell 12 by producing hydrogen and oxygen.

The electrolysis device 52 according to FIG. 1 proves to be disadvantageous in that gas production can continue to occur outside of the actual electrolysis process or the intended electrolysis operation. This can lead to undefined conditions in the electrolysis device 52, which in the worst case scenario can even result in the creation of an ignitable gas mixture. To ensure safety here, additional extensive protective measures are required.

In addition, particularly when starting up the electrolysis device 52 or when shutting down the electrolysis device 52, the case can occur that one or more of the electrolysis cells 12 fall below the polarization voltage Uo due to an uneven distribution of the protective voltage U _s across the series-connected electrolysis cells 12 can. This problem can occur, among other things, because the electrolytic cells 12 are not all identical and/or have a different aging state, that is to say, have different cell characteristics and/or a different aging state. As a result, undesirable fuel cell operation can occur, which can cause the respective electrolysis cells 12 to be damaged. 3 now shows an electrolysis device 10 in which the aforementioned problems can be reduced, if not completely avoided. The electrolysis device 10 is based on the electrolysis device 52 according to FIG. 1, which is why additional reference is made to the relevant statements. Here too, a series connection consisting of a plurality of electrolysis cells 12 is provided, which is connected in parallel to the main rectifier 14 in order to be supplied with electrical energy in the intended electrolysis operation. In this respect, the electrolysis device 10 corresponds to the electrolysis device 52, which is why reference is made to the corresponding comments on FIGS. 1 and 2.

In contrast to the embodiment according to FIG. 1, the electrolysis device 10 according to FIG 12 serves. The protective device 16 is connected to the electrolytic cells 12, namely to their cell connections 28. The protective device 16 has an auxiliary electrical voltage source 22 as an electrical energy source, which serves to provide an auxiliary electrical direct voltage 24. Furthermore, the protective device 16 has contact connections 26 for electrically connecting to the cell connections 28 of the electrolysis cells 12 of the series circuit. In the present embodiment it is therefore provided that all cell connections 28 are electrically coupled to the protective device 16.

The protective device 16 also has respective protection units 40 with connection contacts 72, which are each electrically coupled via the contact connections 26 and the cell connections 28 to a respective one of the electrolysis cells 12, namely their electrodes. Furthermore, the protection units 40 each have two connection connections 34, by means of which they can be electrically coupled to the auxiliary voltage source 22. This makes it possible to use each of the electrolysis Cells 12 must be individually applied with a protective current 76 in order to be able to reliably achieve a cell voltage greater than the polarization voltage Uo, regardless of the intended operation.

The auxiliary electrical voltage source 22 can be electrically coupled, for example, to a public power grid or the like. Each protection unit 40 provides an individual protection current 76 for each of the electrolysis cells 12, so that an individual protection voltage U _s can be achieved.

The protective voltage U _s (FIG 2) is chosen so that no fuel cell effect occurs on any of the electrolysis cells 12, that is, it is avoided that gas residues in a respective electrolysis cell 12 react to form water according to the fuel cell principle and thus release energy. This can lead to significant aging and damage to a respective electrolytic cell 12.

In the present case, a switching unit 36 is also provided, which is connected to the connection contacts 72 of the protection units 40 of the support device 90 and to the contact connections 26 of the electrolysis device 10 or the electrolysis cells 12. The switching unit 36 is not absolutely necessary for the invention and can - depending on requirements - be omitted or modified. In the present embodiment, the switching unit 36 is designed to electrically couple the protection units 40 to the contact connections 26 in order to provide the protective current 76 at the connection contacts 72 depending on a switching state of the switching unit 36. This creates the possibility that the protection units 40 only need to be electrically connected to the electrolysis cells 12 if this is necessary or desired due to the operating situation of the electrolysis device 10. The protection units 40 can be deactivated relative to the electrolytic cells 12 by means of the switching unit 36 when the electrical rolysis cells 12 are operated as intended in electrolysis mode. In addition, it can be provided, for example, that the voltage sensors 44 (see FIG. 7) of the protection units 40 are connected directly to the contact connections 26 for detecting the cell voltages, if it is desired that the cell voltages should be able to be detected independently of the switching state of the switching unit 36 .

The switching unit 36 has an individual switching element 38 for each of the contact connections 26, which in the present case is formed by a reed relay or reed contact. In alternative embodiments, a corresponding relay or a contactor or an electronic switching element can of course also be provided here.

The switching elements 38 are jointly controlled with regard to their respective switching state by the control unit 18 of the support device 90, so that all of the switching elements 38 essentially assume the same switching state. For this purpose, the control unit 18 can include a control circuit which, among other things, also serves to control the protective device 16. In the present case - as will be explained further below - control unit 18 provides an evaluation functionality so that it also takes on a function of an evaluation unit.

To control the switching unit 36, it is provided in the present embodiment that a cell current of the series connection of the electrolysis cells 12 is detected by means of a current sensor (not shown in detail) as a sensor unit. The current sensor supplies a corresponding sensor signal to the control unit 18, which evaluates this signal. As soon as the sensor signal is smaller than a predetermined comparison value, the switching unit 36 is switched from the switched-off switching state to the switched-on switching state. This means that the protective device 16, which is now activated fourth, each electrolytic cell 12 is supplied with the corresponding individual protective current 76.

The protection units 40 are designed identically in the present case. However, this can be different if necessary. One of the protection units 40 is explained as an example using a schematic block diagram representation according to FIG. To provide the protective current 76, the protection unit 40 has an electronic converter 42 coupled to the electrical auxiliary voltage source 22, which in the present case is designed as a current-controllable, galvanically isolating DC/DC converter in the manner of a current source circuit. At the same time, the converter 42 is designed to output the predeterminable protective current 76 depending on a power source control signal. The current source circuit is generally characterized, among other things, in that the current source circuit emits an electrical current for an operating range specified by the design, for example a voltage range or the like, the value of which is essentially dependent only on the current source control signal. For this purpose, the converter 42 is connected to the control unit 18 of the support device 90 via an interface connection 70. The control unit 18 provides, among other things, the corresponding power source control signal, so that the electrolytic cell 12 coupled to the protection unit 40 can be supplied with the individual protective current 76.

In addition, the protection unit 40 has a voltage sensor 44 connected to the connection contacts 72, with which the cell voltage of the electrolytic cell 12 can be detected. A corresponding voltage signal is transmitted from the voltage sensor 44 to the control unit 18 via the interface connection 70. The control unit 18 evaluates, among other things, the voltage signal and, depending on this, determines the protective current 76 to be set for the respective electrolytic cell 12. Depending on the protective current 76 determined in each case, the current source control signal is transmitted to the converter 42. Even if the protective current is 76 can be constant direct current, the protective current 76 provided does not need to be a constant direct current - as will be shown below.

In the present case it is provided that the protection units 40 of the protection device 16 are all designed the same and can be controlled by means of the control unit 18.

4 shows, in a schematic diagram representation for one of the electrolysis cells 12 according to FIG. 3, an example of a protective current 76 for the protection unit 40 coupled to the respective electrolysis cell 12. In the diagram 80 shown in FIG Ordinate assigned to the electric current in A. An abscissa is assigned to a time axis in ms. A graph 74 shows a converter-internal converter control signal of the converter 42, which controls the delivery of the protective current 76. In the present case, the converter control signal 74 is a square-wave signal, so that the converter 42 is able to provide a clocked direct current. The clocked direct current, which represents the protective current 76, is shown by means of a corresponding graph 76. It can be seen that the protective current 76 is switched on or off synchronously with the converter control signal 76 according to the corresponding graph 76.

During this operation, the cell voltage of the electrolytic cell 12 is detected by means of the voltage sensor 44 (see FIG. 7). In this case, no separate lines need to be provided for this, as has already been explained with reference to FIG. It can be seen that the electrolytic cell 12 shows a DC voltage 78 that fluctuates by a small amount as the cell voltage due to the clocked direct current as protective current 76. In the present case, the voltage fluctuation is in a range from approximately 1.25 V to approximately 1.35 V. The voltage curve according to graph 78 results from the capacitive effect of the electrolytic cell 12. This also explains why according to graph 76 During a respective duration of a respective direct current pulse, the amplitude is not constant, but drops slightly. This is also a reaction due to the capacitive property of the electrolytic cell 12.

With the control signal from the control unit 18, an amplitude of the clocked direct current as well as a duty cycle of the clocked direct current can be adjusted as required. For this purpose, the control unit 18 can carry out a corresponding evaluation of the sensor signal from the voltage sensor 44 (see FIGS. 7 and 8). In any case, the amplitude and the duty cycle of the clocked direct current are determined such that the detected electrical cell voltage of the electrolytic cell 12 is greater than the corresponding associated protective voltage U _s . In addition, taking into account the cell voltage and the cell current of the electrolytic cell 12 caused by the clocked direct current as protective current 76, an aging state of the electrolytic cell 12 can be determined depending on an evaluation by the control unit 18. The duty cycle and/or the amplitude of the clocked direct current can then be additionally adjusted depending on the determined aging state of the electrolytic cell 12.

In an alternative embodiment, it can be provided that regulation can be implemented using the sensor signal from the voltage sensor 44. For this purpose, it can be provided that in order to set the duty cycle of the clocked direct current, the cell voltage is compared with an individual protective voltage U _s of the electrolytic cell 12, and a respective current pulse of the clocked direct current is triggered depending on this comparison. The cell voltage can then be compared with a predetermined voltage comparison value that is greater than the individual protection voltage U _s , and the current pulse of the clocked direct current can be terminated depending on this comparison. By selecting the specified voltage, A duty cycle and/or a frequency of the clocked direct current can therefore be set at the same value.

In addition, it can be provided that in an alternative embodiment a constant direct current is also superimposed on the clocked direct current. This can ensure, for example, that the protective current 76 does not reach the value zero. This can improve reliability and security.

5 shows a further schematic diagram representation of an oscillogram 88 of a further protective current 76. The protective current 76 is again shown with a corresponding graph 76. An abscissa is associated with time in ms, whereas an ordinate is associated with a current in A. It can be seen that the clocked direct current in this embodiment has current pulses in a range between 0.5 and 1.5 A. In the present case, the current pulses are spaced apart over a respective period of time, which is approximately 145 ms.

6 shows a further schematic diagram representation of a diagram 86, from which it can be seen how the clocked protective current 76 affects aging of the electrolytic cell 12. An abscissa is associated with the electrical current in A, whereas an ordinate is associated with the electrical voltage in V. A graph 84 shows a polarization curve of an electrolytic cell 12 at the beginning of the application of a protective current 76 according to FIG. A graph 82 shows another polarization curve at the end of an examination period. The investigation was carried out on an electrolysis cell 12 with an electrode area of approximately 10 cm ² with a current supply over a period of 166 hours as the examination period with a protective current 76 of a maximum of approximately 1.3 A. From graphs 84 and 82 it can be seen that there were no significant differences in terms of the polarization curve. This means that no measurable aging of the electrolytic cell 12 has occurred. The frequency of the clocked direct current can be selected in a range from approximately 10 Hz to approximately 100 Hz. Preferably it is in a range of approximately 30 Hz.

8 shows a schematic block diagram of a structure of the electrolysis device 10 with the support device 90. From FIG. 8 it can be seen that in the present case the electrolysis cells 12 are combined as a module in order to realize a modular or modular structure of the electrolysis device 10. Fluid connections 98 (not shown) are connected to the module, via which educt water to be broken down electrolytically is supplied and hydrogen and oxygen, which are produced during the intended electrolysis, can be removed as products. Each of the electrolysis cells 12 is electrically connected to a respective power source circuit 42 in order to be able to be individually supplied with a cell current. Furthermore, each of the electrolysis cells 12 is electrically connected to a respective voltage sensor 44. In the present case, both the voltage sensors 44 and the current source circuits 42 are connected to the control unit 18 for signaling purposes. The control unit 18 serving as an evaluation unit is designed to determine aging states of all electrolysis cells 12 coupled to the support device 90 and, depending on the determined aging states, to determine control data for starting up or shutting down the electrolysis device 10. This control data is transmitted from the control unit 18 to the higher-level electrolysis control 32 via a communication connection (not shown). The electrolysis control 32 serves for the higher-level control of the electrolysis device 10. The electrolysis control 32 can be connected to more than a single electrolysis device 10 and, for example, can jointly control all electrolysis devices 10 that are in communication with it. In addition, it is provided here that the control unit 18 communicates with further control units 18 of further support devices 90 is coupled, which serve the operation of further electrolysis devices 10.

9 shows a schematic perspective view of a first embodiment of an arrangement of the supporting device 90 on an electrolysis device 10 formed as a module with a module housing 96. It can be seen that the support device 90 has a separately manageable housing 94 which has a substantially flat cuboid structure. The supporting device 90 further has a plug connector 92 for electrically connecting the supporting device 90 to the electrolysis cells 12, which in the present case is connected to the housing 94 via an electrical connecting line 100. In this way, a simple connection of the support device 90 to the electrolysis device 10 can be achieved. The plug connector 92 is connected to the module on one end face and is attached to the module housing 96 in this way.

10 shows, in a schematic representation like FIG. 9, a second embodiment of an arrangement of the support device 90 on an electrolysis device 10 designed as a module with a module housing 96. This embodiment is based on the embodiment according to FIG. 9, which is why reference is made in addition to the comments on FIG. 9. This embodiment differs from the first embodiment in that the plug connector 92 is formed in one piece with the housing 94 . The connecting line 100 can thereby be saved. The plug connector 92 is formed at one end of the housing 94 and protrudes from a plane spanned by the housing 94 . As a result, the plug connector 92 can be connected to the module essentially as in the first embodiment according to FIG. 9, in particular plugged onto the module housing 96.

Even if the principle of the invention has been explained above based on the application to individual electrolysis cells of the electrolysis device, the principle of the invention is nevertheless equally applicable to an electrolysis device which has one or more cell blocks, whereby a respective cell block can comprise two or more electrolysis cells. The cell-specific aspects can therefore - easily apparent to the person skilled in the art - also be applied to a respective cell block in an essentially appropriate manner. The treatment of cell blocks can also be achieved through a simple, slight adjustment. Of course, combinations of cell blocks and individual electrolysis cells can also be provided.

The exemplary embodiments serve exclusively to explain the invention and are not intended to limit it.

Claims

Patent claims

1. Support device (90) for an electrolysis device (10) having a plurality of electrolysis cells (12), with:

- Connection contacts (72) for electrical coupling with respective electrodes of the electrolysis cells (12), characterized by

- at least one voltage detection unit for detecting a cell voltage of a respective electrolysis cell (12),

- An evaluation unit (18) coupled in terms of signals to the at least one voltage detection unit for determining at least one cell characteristic or at least one aging condition for a respective electrolytic cell

( 12 ), as well

- A number of controllable electronic power source circuits corresponding to the majority of electrolysis cells (12).

(42), wherein a respective one of the current source circuits (42) is electrically coupled to electrodes of a respective one of the electrolysis cells (12) and is designed to individually apply a direct current to the respective electrolysis cell (12), which is adjustable depending on a current source control signal.

2. Support device (90) according to claim 1, characterized in that the voltage detection unit has a number of voltage sensors (44) corresponding to the plurality of electrolysis cells (12), each of the voltage sensors (44) having electrodes of a respective one of the electrolysis cells ( 12) is electrically coupled and is designed to detect a cell voltage of the respective electrolysis cell (12) and to emit a respective voltage signal depending on the detected cell voltage.

3. Support device (90) according to one of the preceding claims, characterized by at least one current sensor for detecting a cell current of at least one of the electrolysis cells (12) and for emitting a current signal depending on the detected cell current.

4. Support device (90) according to one of the preceding claims, characterized in that the evaluation unit (18) is designed to record the cell voltage and the cell current over a predeterminable period of time and, depending on this, the cell characteristics and / or the aging state of the electrolysis cell (12) to determine.

5. Support device (90) according to claim 4, characterized in that the evaluation unit (18) is designed to determine cell characteristics and / or aging conditions of all electrolysis cells (12) coupled to the support device (90) and depending on the determined aging conditions To determine control data for an operating state in electrolysis operation, starting up and / or shutting down the electrolysis device (10).

6. Support device (90) according to one of the preceding claims, characterized by a separately manageable housing (94) which has a plug connector (92) for electrically connecting the support device (90) to the electrolysis cells (12).

7. Support device (90) according to one of the preceding claims, characterized in that the evaluation unit (18) is designed to determine the operating states of all electrolysis cells (12) coupled to the evaluation unit (18) and, depending on the determined operating states, a status signal for one to provide a higher-level electrolysis control (32) in order to control the cell current depending on the status signal.

8. Electrolysis device (10) with a plurality of electrolysis cells (12), characterized by a support device (90) according to one of the preceding claims. 9. A method for operating an electrolysis device (10) having a plurality of electrolysis cells (12), wherein respective electrodes of the electrolysis cells (12) for electrical coupling with a support device (90) for the electrolysis device (10) according to one of the preceding claims with connection contacts ( 72) of the support device (90) are electrically coupled, characterized in that cell voltages of the electrolysis cells (12) are detected by means of at least one voltage detection unit of the support device (90) which is electrically coupled to the connection contacts (72), the voltage detection unit depending on the respective detected electrical voltage provides a respective voltage signal, the voltage signals being evaluated by means of an evaluation unit (18) in order to determine at least one cell characteristic or at least one aging state for a respective electrolytic cell (12).

10. The method according to claim 9, in which a respective one of the power source circuits (42) of the support device (90) is electrically coupled to electrodes of a respective one of the electrolysis cells (12), the respective electrolysis cell (12) being individually supplied with a direct current which depends is set by a power source control signal.