Operation of an electrolysis device having a plurality of electrolysis cells

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

[0001] Description

[0002] Operating an electrolysis device having a plurality of electrolysis cells

[0003] The invention relates to a support device for an electrolysis device having a plurality of electrolysis cells, with connection contacts for electrically coupling to respective electrodes of the electrolysis cells. Furthermore, the invention relates to an electrolysis device having 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 electrically coupling to a support device for the electrolysis device.

[0004] Electrolysis devices, support devices therefor, and methods for operating electrolysis devices are extensively known in the prior art, so that, in principle, separate written documentation is not required. 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 omitted here.

[0005] Electrolysis devices comprising a single, but in particular a plurality of, electrolysis cells, which are generally at least partially electrically connected in series, serve, among other things, to produce substances that are preferably usable on an industrial scale, for example hydrogen in water electrolysis, carbon monoxide in carbon dioxide electrolysis, or the like. For this purpose, during normal operation, at least two electrodes of a respective electrolysis 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 substance to be provided by the electrolysis, a corresponding electrical direct current is provided by an electrolysis energy source as the electrolysis current. In electrolysis cells connected in series, this direct current flows through all of the series-connected battery cells.The series circuit is electrically coupled to an electrolysis energy source. However, it is also possible to connect electrolysis cells not only in series, but also, at least partially, in parallel.

[0006] Particularly in aqueous electrolysis processes, such as chlorine / alkali electrolysis, PEM electrolysis, or the like, a membrane is often provided that separates the respective reaction chambers of the respective reaction zones of a respective electrolysis cell, in which the respective electrodes are arranged. A catalyst is often arranged on such a membrane to enable or catalytically accelerate the electrolysis process. Electrolysis is usually achieved by applying the electrolysis current or a suitable electrical direct voltage, also called cell voltage, to the electrodes of a respective electrolysis cell during normal operation.

[0007] A transition from or to an operating state that differs from the intended operating state proves to be at least partially critical for a particular electrolysis cell. This applies 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 during shutdown after intended operation, residual substances, in particular dissolved or gaseous residual gases, may still be present in the electrolysis cell, which may under certain circumstances cause the electrolysis cell to exhibit fuel cell functionality. However, this can cause irreversible damage to the electrolysis cell, which is why 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 electrolysis cell outside of its intended operation. This voltage is selected so that the fuel cell functionality can be largely prevented. For an electrolysis cell used to electrolyze water, for example, the protective voltage can be approximately 1.25 V. Once the electrolysis cell has cooled down sufficiently and residual gases have been removed, the protective voltage can be deactivated.

[0008] Support devices of this type serve, among other things, to support or ensure the safe operation of the electrolysis cells, in particular of 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. EP 3 982 501 A1 discloses such a device, for example.

[0009] Furthermore, it has been shown that electrolysis cells age differently and / or can have differing characteristics. This can prove particularly problematic when electrolysis cells are connected in series, if a protective voltage is to be provided as a polarization voltage by a voltage applied to the series circuit. Due to the different aging or characteristics, it can happen that, particularly when the electrolysis cells are connected in series, the voltage applied to the series circuit is not distributed evenly among all the electrolysis cells connected in series. It is therefore then necessary to select a voltage for the series circuit that is large enough that the protective voltage can still be reliably achieved for the most unfavorable electrolysis cell.However, this results in the other cells being subjected to a correspondingly high voltage, which can be significantly higher than the protective voltage, so they continue to operate in electrolysis mode. To prevent an explosive mixture in these electrolysis cells, it is therefore common practice to purge them with nitrogen.

[0010] EP 3 982 501 A1 also discloses applying the protective voltage to each electrolysis cell individually. However, providing the respective protective voltages for the electrolysis cells proves to be comparatively complex. Furthermore, the aging state and characteristics of the electrolysis cells are not taken into account, so undesirable conditions can still occur.

[0011] 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.

[0012] With regard to a generic support device, the invention proposes in particular that the support device has at least one voltage detection unit for detecting a cell voltage of a respective one of the electrolysis cells, as well as an evaluation unit which is signal-coupled to the at least one voltage detection unit for determining at least one cell characteristic or at least one aging state for a respective one of the electrolysis cells, wherein a number of controllable electronic current 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 supply the respective electrolysis cell individually with a direct current which is adjustable depending on a current source control signal.

[0013] With regard to a generic electrolysis device, the invention proposes in particular that the electrolysis device has a support device according to the invention.

[0014] With regard to a generic method, the invention proposes in particular that cell voltages of the electrolysis cells are detected by means of at least one voltage detection unit of the support device which is electrically coupled to the connection contacts, wherein the voltage detection unit provides a respective voltage signal depending on the respective electrical voltage detected, wherein the voltage signals are evaluated by means of an evaluation unit in order to determine at least one cell characteristic or at least one aging state for a respective electrolysis cell.

[0015] The invention is based, among other things, on the idea of ​​recording the cell voltages of the individual electrolysis cells, particularly when the electrolysis 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 ageing state based on this data. For this purpose, it is possible to take into account, for example, the respective cell current to which the respective electrolysis cells are or were subjected. Of course, both the cell characteristic and the ageing state of the respective electrolysis cell can also be determined. This data can be used to better operate the electrolysis cells individually, for example by individually adjusting a cell current, so that the electrolysis cells can be operated individually in their most optimal operating state.This can be provided, in particular, for the intended electrolysis operation, the start-up of the electrolysis device, and / or the shut-down of the electrolysis device. Furthermore, it can be achieved that, for example, data is provided to a higher-level electrolysis control system of the electrolysis device that allows the load capacity of the respective electrolysis cell to be identified. This load capacity, which can also include the aging state, can be used to adjust the output of the electrolysis cell within a predetermined operating range. This can be used, for example, to vary or adjust the electrolysis output of the electrolysis device, or similarly.

[0016] If, for example, a low electrolysis output is to be activated, it is advantageous to operate the electrolysis cells with an unfavorable state of age if possible, whereas if a high electrolysis output is desired, it is preferable to activate electrolysis cells with a low state of age, i.e. preferably electrolysis cells that are essentially new. Of course, it can also be provided that through the intended operation of the electrolysis cells and the respective activation and deactivation of the electrolysis cells, different states of age of the electrolysis cells can be equalized. This makes use of, among other things, the knowledge that a cell voltage at a given cell current can vary depending on the state of age. For a given cell current, the cell voltage generally increases with increasing age.The aging state of the electrolysis cell can therefore be determined, for example, based on the electrolysis cell's operating parameters. Operating parameters can include, for example, cell voltage, cell current, electrolysis cell temperature, fluid flow values ​​such as liquids and / or gases, and the like.

[0017] Furthermore, it can be considered that the cell voltage may also depend, among other things, on the activation of catalysts and the like used in the respective electrolysis cells. Thus, 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 preferably be achieved.

[0018] At the same time, the support device of the invention also enables the start-up and shut-down of the electrolysis device to be implemented more safely and reliably overall. This can be achieved, among other things, by detecting the respective cell voltages of the electrolysis cells during intended operation and / or during start-up or shut-down and taking them into account for setting a respective cell current. Preferably, the respective cell current can also be taken into account. This is preferably done depending on the determined cell characteristic or the determined aging state. The cell characteristic can, for example, comprise an individual characteristic curve, optionally further cell parameters and / or the like of a respective one of the electrolysis cells.

[0019] 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 an electrical coupling, so that the desired electrical connection to the electrodes of the electrolysis cells can be established. The support device further has the voltage detection unit, which serves to detect the cell voltages of the electrolysis 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 manner. The voltage detection unit provides corresponding voltage signals, which are transmitted to the signal-coupled evaluation unit.Thus, the corresponding voltage signals are available in the evaluation unit, allowing it to determine at least the cell characteristics or at least the aging state of the respective electrolysis cell. The support device, in particular the voltage detection unit and, if applicable, 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.

[0020] The invention proves 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 used in an electrolysis device that has at least partially parallel-connected electrolysis cells. Of course, combinations of series and parallel connections of electrolysis cells can also be provided.

[0021] According to a further development, it is proposed that the voltage detection unit has a number of voltage sensors corresponding to the plurality of electrolysis cells, wherein each of the voltage sensors is electrically coupled to electrodes of a respective electrolysis cell and is designed to detect a cell voltage of the respective electrolysis cell and to output a respective voltage signal depending on the detected cell voltage. The voltage detection unit can therefore simultaneously detect the cell voltages of the plurality of electrolysis cells and output corresponding voltage signals. This enables very fast signal processing. Overall, this can improve the support device and, if necessary, also improve its function.

[0022] Furthermore, it is proposed that the support device have at least one current sensor for detecting a cell current of 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 generally suffice. However, it can also be provided that, preferably for each of the electrolysis cells, a separate individual current sensor is provided for detecting the cell current. By means of the current sensor, the cell current can be detected, preferably 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 at least one current signal into account when evaluating.

[0023] It is further proposed that the support device comprise a number of controllable electronic current source circuits corresponding to the plurality of electrolysis cells, wherein each of the current source circuits is electrically coupled to electrodes of a respective one of the electrolysis cells and is configured to individually supply the respective electrolysis cell with a direct current that is adjustable depending on a current source control signal. This makes it possible to individually supply each of the plurality of electrolysis cells with a corresponding direct current.This proves particularly advantageous when the electrolysis device or the electrolysis cells are operated outside of the intended electrolysis mode, in that the electrolysis cells are preferably supplied with a protective current or polarization current, for example to suppress or prevent undesired fuel cell functionality. This is particularly the case when starting up the electrolysis device or shutting down the electrolysis device, during which electrolysis cells connected in series in particular may otherwise be subjected to uneven electrical current. Using the individually provided current 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 protection current is preferably dependent on the determined cell characteristics and / or the determined aging state.

[0024] Each of the current source circuits can be adjusted using the current source control signal. The current source control signal can be provided for one or more of the current source circuits, for example, by the evaluation unit or by the higher-level electrolysis control system of the electrolysis device. This makes it possible to operate each of the electrolysis cells in the optimal operating state.

[0025] It is further 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 electrolysis 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 in a particularly advantageous manner. For this purpose, it can be provided that the evaluation unit has data from a new electrolysis cell at its disposal as reference or starting values, or retrieves this data as a data set from an external data storage device via a communication connection. By means of the respective current source circuit, it is thus even possible to currently record and store 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 subsequently determine a change in the respective cell characteristics, in particular the operational aging state of the respective electrolysis cell. Among other things, the cell characteristics can also include operating states, changes in operating states, operating parameters and / or changes in operating parameters that can be determined for the electrolysis cells. Of course, it can also be provided that data relating to a state relating to an end of use of the electrolysis cells is stored in a retrievable manner, whereby the evaluation unit can determine whether a respective one of the electrolysis cells has reached the end of use.When the end of service life is reached, the evaluation unit can, for example, emit a signal indicating that the respective electrolysis cell requires maintenance or replacement. This can further improve the overall function of the electrolysis device. At the same time, the determined aging states of the electrolysis cells can be used to provide individual current source control signals based on these values, so that the electrolysis cells can be supplied with the cell current preferably depending on their respective determined aging state. This also enables a further improvement in the overall operation of the electrolysis device.

[0026] It proves 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 during electrolysis operation, starting up and / or shutting down the electrolysis device. This control data can, among other things, also include data relating to the current source control signals, so that the most optimal operation of the electrolysis cells can be achieved, particularly when starting up or shutting down the electrolysis device, especially when they are connected in series. It is further proposed that the support device have a separately handleable housing which has a 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 handled housing can be a closed housing, so that the support device is reliably protected from external influences. This is particularly advantageous if hazardous substances, such as an explosive gas mixture, an aggressive atmosphere, and / or the like, may occur in the vicinity of the support device. The connection contacts are preferably also arranged on the housing in a manner that allows for electrical contact.

[0027] According to a further embodiment, it is proposed that the evaluation unit be configured to determine the 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 controller in order to control the cell current depending on the status signal. The status signal can be used to adjust the individual current source control signals. However, it can also be used to control the cell current to be provided by the higher-level electrolysis controller during normal electrolysis operation. This can, in particular, prevent overloading of individual electrolysis cells, especially severely aged electrolysis cells.This makes it possible, for example, to appropriately control the cell current at least during normal electrolysis operation or at least outside of normal electrolysis operation during protective operation. Furthermore, operation of the electrolysis cells outside of permissible normal electrolysis operation, which may be determined, for example, by a cell design and / or measurement parameters, can be avoided. Overall, the operational reliability of the electrolysis device and its service life can be further improved or increased.

[0028] The support device preferably has a communication interface, which connects it to the higher-level electrolysis control system of the electrolysis device. The communication interface can be configured for wireless or wired communication.

[0029] The support device can further be designed to detect further operating parameters of the electrolysis cells, preferably cell-specifically. For this purpose, the support device can have suitable parameter sensors, which can be arranged at least partially integrated in the support device or else 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 velocity of process fluids in the respective electrolysis cell, in particular with regard to electrolysis cells for the electrolysis of water, to measure water vapor, to measure a gas composition, for example, to determine whether a gas composition contains an ignitable mixture, to measure a pressure, and / or the like.Preferably, these parameter sensors can also be signal-coupled to the evaluation unit, so that the evaluation unit can perform the additional evaluation depending on these signals. This can also further improve the operation of the electrolysis device.

[0030] In the method according to the invention for operating a plurality of electrolysis cells, a respective one of the current source circuits of the support device is advantageously electrically coupled to electrodes of a respective one of the electrolysis cells, wherein the respective electrolysis cell is individually supplied with a direct current which is adjusted as a function of a current source control signal.

[0031] Thus, both protective operation and normal operation of a plurality of electrolysis cells can be carried out individually for each cell using the support device. At the same time, for example, the determined aging states of the electrolysis cells can be used to provide individual current source control signals depending thereon, so that the electrolysis cells are supplied with the cell current, preferably depending on their respectively determined aging state. Depending on the operating mode, a protective current is supplied to a respective electrolysis cell during protective operation, or an operating current for normal electrolysis operation is supplied to a respective electrolysis cell during normal operation.

[0032] The advantages and effects stated 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 method features, and vice versa.

[0033] The exemplary embodiments explained below are preferred embodiments of the invention. The features and combinations of features stated above in the description as well as the features and combinations of features mentioned in the following description of exemplary embodiments and / or shown alone in the figures can be used not only in the respective combination stated, but also in other combinations. Thus, embodiments are to be regarded as being encompassed by the invention or disclosed which are not explicitly shown and explained in the figures, but which arise from and can be produced by means of separate combinations of features from the explained embodiments.The features, functions, and / or effects illustrated by the exemplary embodiments may, in and of themselves, represent individual, independently considered features, functions, and / or effects of the invention, each of which also further develops the invention independently of one another. Therefore, the exemplary embodiments are intended to encompass combinations other than those in the explained embodiments. Furthermore, the described embodiments may also be supplemented by further features, functions, and / or effects of the invention already described.

[0034] In the figures, the same reference symbols denote the same features and functions.

[0035] They show:

[0036] FIG 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;

[0037] FIG 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;

[0038] FIG 3 shows a schematic circuit diagram like FIG 1 of an electrolysis device in which a protection unit is connected in parallel to each individual electrolysis cell;

[0039] FIG. 4 is a schematic diagram in which a clocked current 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 are shown by means of respective graphs, FIG. 5 is a schematic diagram of an oscillogram of a further protective current,

[0040] FIG 6 is a schematic diagram of an ageing determined based on polarization characteristics of the electrolytic cell subjected to the protective current according to FIG 5,

[0041] FIG 7 is a schematic block diagram of a protection unit according to FIG 3,

[0042] FIG 8 shows a schematic block diagram of the structure of the electrolysis device with the support device,

[0043] FIG 9 is a schematic perspective view of a first embodiment of an arrangement of the support device on an electrolysis device designed as a module, and

[0044] FIG 10 in a schematic representation like FIG 9 a second embodiment of an arrangement of the support device on an electrolysis device designed as a module.

[0045] FIG. 1 shows a schematic circuit diagram of an electrolysis device 52 with a plurality of electrolysis cells 12 connected electrically in series. The electrolysis cells 12 serve, in this case, for the electrolysis of water into hydrogen and oxygen in a reaction chamber (not shown in further detail), which is formed between the respective electrodes of the respective electrolysis cell 12. In alternative embodiments, a different substance can, of course, also be subjected to electrolysis as a reactant 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 the electrolysis energy source. The main rectifier 14 provides an operating voltage 50, which is applied to the series connection of the electrolysis cells 12, so that during intended operation, namely the electrolysis operation, an electrolysis current 48 flows through the electrolysis cells 12.

[0046] A series circuit comprising a polarization rectifier 54 and a protective inductance 58 as an auxiliary energy source is connected in parallel to the main rectifier 14 to the series circuit of the electrolysis 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, said rectifier voltage being selected such that a protective current 56 is established, which in turn is selected so large that all electrolysis cells 12 are supplied with at least a sufficiently large polarization voltage Uo (FIG. 2), which is set greater than or equal to a required protective voltage U s , are applied. This is intended to prevent undesirable processes in the electrolysis cells 12 outside of the intended electrolysis operation.

[0047] FIG. 2 shows a schematic diagram 60 in which an ordinate 62 is assigned to a cell voltage at respective cell terminals 28 of an individual electrolysis cell 12. An abscissa 64 is assigned to the corresponding cell current of this electrolysis cell 12. A graph 66 represents the dependence of the cell voltage on the cell current as a polarization characteristic. U N denotes an electrolysis voltage which is established at the electrolysis cell 12 during normal electrolysis operation when the electrolysis cell 12 is supplied with the electrolysis current 48 of an electrolysis current intensity I n The intersection point of the graph 66 with the ordinate 62 defines the polarization voltage Uo, below which a change in polarization of the cell current can result. In the present embodiment of the electrolysis cell 12 for the electrolysis of water, the electrolysis voltage U Nabout 1.8 to 1.9 V. The polarization voltage Uo can be about 1.48 V in the present embodiment. Depending on the design of the electrolysis cells 12, the polarization voltage Uo can also be in a range from about 1.25 V to about 1.45 V. At a cell voltage greater than about 1.48 V, the electrolysis functionality begins in the electrolysis cell 12 by producing hydrogen and oxygen.

[0048] The electrolysis device 52 shown in FIG. 1 proves to be disadvantageous in that gas production can continue 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, can even result in the formation of an ignitable gas mixture. To ensure safety in this case, comprehensive additional protective measures are required.

[0049] In addition, particularly when starting up the electrolysis device 52 or shutting down the electrolysis device 52, the case may occur that due to an uneven distribution of the protective voltage U sacross the series-connected electrolysis cells 12, the polarization voltage Uo may fall below the limit in one or more of the electrolysis cells 12. This problem may occur, among other things, because the electrolysis cells 12 are not all identical and / or have a different state of aging, i.e., they have different cell characteristics and / or a different state of aging. This may result in undesired fuel cell operation, which may damage the respective electrolysis cells 12. FIG. 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 reference is made to the relevant explanations.Here, too, a series circuit comprising a plurality of electrolysis cells 12 is provided, which are connected in parallel to the main rectifier 14 to be supplied with electrical energy during normal electrolysis operation. In this respect, the electrolysis device 10 corresponds to the electrolysis device 52, which is why reference is made to the corresponding explanations for FIGS. 1 and 2.

[0050] In contrast to the embodiment according to FIG. 1, the electrolysis device 10 according to FIG. 3 is provided with a support device 90 with a protective device 16 and a control unit 18, which serves to provide an individual protective current 76 (FIG. 4) for each of the series-connected electrolysis cells 12. The protective device 16 is connected to the electrolysis cells 12, specifically to their cell terminals 28. The protective device 16 has an auxiliary electrical voltage source 22 as an electrical energy source, which serves to provide an auxiliary DC voltage 24. Furthermore, the protective device 16 has contact terminals 26 for electrically connecting to the cell terminals 28 of the electrolysis cells 12 in the series circuit. In the present embodiment, it is therefore provided that all cell terminals 28 are electrically coupled to the protective device 16.

[0051] The protective device 16 further comprises respective protective units 40 with connection contacts 72, each of which is electrically coupled to a respective one of the electrolysis cells 12, specifically their electrodes, via the contact terminals 26 and the cell terminals 28. Furthermore, the protective units 40 each have two connection terminals 34, by means of which they can be electrically coupled to the auxiliary voltage source 22. This makes it possible to individually apply a protective current 76 to each of the electrolysis cells 12 in order to reliably achieve a cell voltage greater than the polarization voltage Uo, even independently of intended operation.

[0052] The auxiliary electrical voltage source 22 can, for example, be electrically coupled to a public power grid or the like. Each protection unit 40 provides an individual protection current 76 for the respective electrolysis cells 12, so that an individual protection voltage U s can be achieved.

[0053] The protective voltage U s (FIG. 2) is selected such that no fuel cell effect occurs in any of the electrolysis cells 12. This means that residual gases in a given electrolysis cell 12 are prevented from reacting to form water according to the fuel cell principle and thus releasing energy. This can lead to significant aging and damage to a given electrolysis cell 12.

[0054] In the present case, a switching unit 36 ​​is also provided, which is connected to the connection contacts 72 of the protective units 40 of the support device 90 and to the contact terminals 26 of the electrolysis device 10 or the electrolysis cells 12. The switching unit 36 ​​is not absolutely necessary for the invention and can be omitted or modified as needed. In the present embodiment, the switching unit 36 ​​is designed to electrically couple the protective units 40 to the contact terminals 26 for providing 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 protective units 40 only need to be electrically connected to the electrolysis cells 12 when this is necessary or desired due to the operating situation of the electrolysis device 10.Thus, the protection units 40 can be deactivated relative to the electrolysis cells 12 by means of the switching unit 36 ​​when the electrolysis cells 12 are operated as intended in electrolysis mode. Furthermore, 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 terminals 26 for detecting the cell voltages if it is desired that the cell voltages can be detected independently of the switching state of the switching unit 36.

[0055] The switching unit 36 ​​has an individual switching element 38 for each of the contact terminals 26, which in this case is formed by a reed relay or reed contact. In alternative embodiments, a corresponding relay or contactor, or even an electronic switching element, can of course also be provided here.

[0056] 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 comprise a control circuit, which, among other things, also serves to control the protective device 16. In the present case, the control unit 18—as will be explained further below—provides an evaluation functionality, so that it also assumes the function of an evaluation unit.

[0057] To control the switching unit 36, the present embodiment provides for a cell current in the series connection of the electrolysis cells 12 to be detected by means of a current sensor (not shown in detail). The current sensor delivers 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 off switching state to the on switching state. This means that each electrolysis cell 12 is supplied with the corresponding individual protective current 76 by the protective device 16, which is now activated as a result.

[0058] The protection units 40 are identical in design here. However, this can also be different if required. One of the protection units 40 is explained by way of example using a schematic block diagram according to FIG. 7. To provide the protection current 76, the protection unit 40 has an electronic converter 42 coupled to the auxiliary electrical voltage source 22, which converter is designed here 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 protection current 76 depending on a current source control signal. The current source circuit is generally characterized, among other things, in particular in that the current source circuit outputs an electrical current for an operating range predetermined by rating, for example a voltage range or the like, the value of which depends essentially 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 current source control signal so that the electrolysis cell 12 coupled to the protection unit 40 can be supplied with the individual protection current 76.

[0059] In addition, the protection unit 40 has a voltage sensor 44 connected to the connection contacts 72, with which the cell voltage of the electrolysis cell 12 can be detected. A corresponding voltage signal is transmitted from the voltage sensor 44 via the interface connection 70 to the control unit 18. 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 electrolysis cell 12. The current source control signal is transmitted to the converter 42 depending on the respectively determined protective current 76. Even though the protective current 76 can be a constant direct current, the provided protective current 76 does not need to be a constant direct current, as will be shown below.

[0060] In the present case, it is provided that the protection units 40 of the protection device 16 are all designed identically and can be controlled by means of the control unit 18.

[0061] FIG. 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 protective unit 40 coupled to the respective electrolysis cell 12. In the diagram 80 shown in FIG. 4, a left ordinate is assigned to the electrical voltage in V and a right ordinate to the electrical current in A. An abscissa is assigned to a time axis in ms. A graph 74 represents an internal converter control signal of the converter 42, which controls the output of the protective current 76. In the present case, the converter control signal 74 is a square-wave signal, so that the converter 42 can provide a clocked direct current. The clocked direct current, which represents the protective current 76, is represented by means of a corresponding graph 76. It can be seen that the protection current 76 is switched on or off synchronously with the converter control signal 76 according to the corresponding graph 76.

[0062] During this operation, the cell voltage of the electrolysis cell 12 is detected by the voltage sensor 44 (see FIG. 7). No separate lines need to be provided for this purpose, as already explained with reference to FIG. 7. It can be seen that the electrolysis cell 12 exhibits a DC voltage 78 as cell voltage that fluctuates slightly due to the pulsed DC current as the protective current 76. The voltage fluctuation in this case lies 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 electrolysis cell 12. This also explains why, according to graph 76, the amplitude is not constant during a respective duration of a respective DC pulse, but rather drops slightly. This is also a reaction due to the capacitive property of the electrolysis cell 12.

[0063] The control signal from control unit 18 can be used to adjust the amplitude of the pulsed direct current as well as the duty cycle of the pulsed direct current as needed. For this purpose, control unit 18 can perform a corresponding evaluation of the sensor signal from voltage sensor 44 (see FIGS. 7 and 8). In any case, the amplitude and duty cycle of the pulsed direct current are determined such that the detected electrical cell voltage of electrolysis cell 12 is greater than the corresponding protective voltage U sFurthermore, taking into account the cell voltage and the cell current of the electrolysis cell 12 caused by the pulsed direct current as the protective current 76, an aging state of the electrolysis cell 12 can be determined based on an evaluation by the control unit 18. The duty cycle and / or the amplitude of the pulsed direct current can then be additionally adjusted depending on the determined aging state of the electrolysis cell 12.

[0064] In an alternative embodiment, it can be provided that a control can be implemented using the sensor signal of the voltage sensor 44. For this purpose, it can be provided that, in order to adjust the duty cycle of the pulsed direct current, the cell voltage is compared with an individual protective voltage U sof the electrolysis 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 comparison value, a duty cycle and / or a frequency of the clocked direct current can be set.

[0065] Furthermore, in an alternative embodiment, a constant direct current can be superimposed on the pulsed direct current. This can, for example, ensure that the protective current 76 does not reach zero. This can improve reliability and safety.

[0066] FIG. 5 shows, in a further schematic diagram, an oscillogram 88 of a further protective current 76. The protective current 76 is again represented by a corresponding graph 76. An abscissa is assigned to the time in ms, whereas an ordinate is assigned to 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. The current pulses are spaced apart by a respective period of approximately 145 ms.

[0067] FIG. 6 shows a further schematic diagram 86, which shows how the pulsed protective current 76 affects the aging of the electrolysis cell 12. An abscissa is assigned to the electrical current in A, whereas an ordinate is assigned to the electrical voltage in V. A graph 84 shows a polarization curve of an electrolysis cell 12 at the beginning of the application of a protective current 76 according to FIG. 5. A graph 82 shows a further polarization curve at the end of a test period. The test was carried out on an electrolysis cell 12 with an electrode area of ​​approximately 10 cm 2with current applied over a period of 166 hours as the test period with a maximum protective current 76 of approximately 1.3 A. Graphs 84 and 82 show that there were no significant differences in the polarization curve. This indicates that no measurable aging of the electrolytic cell 12 occurred. The frequency of the pulsed direct current can be selected within a range of approximately 10 Hz to approximately 100 Hz. Preferably, it is within a range of approximately 30 Hz.

[0068] FIG. 8 shows a schematic block diagram of the structure of the electrolysis device 10 with the support device 90. From FIG. 8 it can be seen that in this case the electrolysis cells 12 are combined as a module in order to realize a modular structure of the electrolysis device 10. Fluid connections 98 (not shown in detail) are connected to the module, via which reactant water to be electrolytically decomposed can be supplied and via which hydrogen and oxygen, which arise as products during the intended electrolysis, can be removed. Each of the electrolysis cells 12 is electrically connected to a respective current 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. 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, which serves as an evaluation unit, is designed to determine the 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 controller 32 via a communication link (not shown). The electrolysis controller 32 serves as the higher-level control of the electrolysis device 10. The electrolysis controller 32 can be connected to more than one electrolysis device 10 and, for example, jointly control all electrolysis devices 10 that are in communication with it.Furthermore, it is provided here that the control unit 18 is coupled in terms of communication technology to further control units 18 of further support devices 90 which serve to operate further electrolysis devices 10.

[0069] FIG 9 shows a schematic perspective view of a first embodiment of an arrangement of the support device 90 on an electrolysis device 10 designed as a module with a module housing 96. It can be seen that the support device 90 has a separately handleable housing 94 which has a substantially flat, cuboid-shaped structure. The support device 90 further has a plug connector 92 for electrically connecting the support 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 at one end and is thus attached to the module housing 96.

[0070] FIG. 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 to the explanations for FIG. 9. This embodiment differs from the first embodiment in that the plug connector 92 is designed as one piece with the housing 94. The connecting line 100 can therefore be omitted. The plug connector 92 is formed at one end of the housing 94 and projects from a plane defined by the housing 94. As a result, the plug connector 92 can be connected to the module essentially in the same way as in the first embodiment according to FIG. 9, in particular it can be plugged onto the module housing 96.

[0071] Even though the principle of the invention has been explained above with reference to its 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, wherein each cell block can comprise two or more electrolysis cells. The cell-specific aspects can therefore - as will be readily apparent to a person skilled in the art - essentially be adapted and applied to a respective cell block. The treatment of cell blocks can thus also be achieved by means of a simple, easy adaptation. Of course, combinations of cell blocks and individual electrolysis cells can also be provided.

[0072] The embodiments serve solely 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), comprising: - connecting 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 one of the electrolysis cells (12), - an evaluation unit (18) coupled to the at least one voltage detection unit for signal processing for determining at least one cell characteristic or at least one ageing state for a respective one of the electrolysis cells ( 12 ) , and - a number of controllable electronic current source circuits corresponding to the plurality 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 supply the respective electrolysis cell (12) with a direct current 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), wherein a respective one of the voltage sensors (44) is electrically coupled to electrodes of a respective one of the electrolysis cells (12) 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 detect the cell voltage and the cell current over a predeterminable period of time and to determine the cell characteristic and / or the aging state of the electrolysis cell (12) depending thereon.

5. Support device (90) according to claim 4, characterized in that the evaluation unit (18) is designed to determine cell characteristics and / or 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 an operating state in the electrolysis operation, a start-up and / or a shutdown of the electrolysis device (10).

6. Support device (90) according to one of the preceding claims, characterized by a separately handleable 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 operating states of all electrolysis cells (12) coupled to the evaluation unit (18) and, depending on the determined operating states, to provide a state signal for a higher-level electrolysis control (32) in order to control the cell current depending on the state 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) are electrically coupled to connection contacts (72) of the support device (90) for electrical coupling to a support device (90) for the electrolysis device (10) according to one of the preceding claims, 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) electrically coupled to the connection contacts (72), wherein the voltage detection unit provides a respective voltage signal depending on the respectively detected electrical voltage, wherein the voltage signals are 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 electrolysis cell (12).

10. The method according to claim 9, wherein a respective one of the current 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 is adjusted in dependence on a current source control signal.

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