OPERATING AN ELECTROLYSIS DEVICE

Abstract

An electrolysis device having at least one electrolytic cell and an electrolysis energy source connected to the at least one electrolytic cell. A method for operating an electrolysis device includes applying an electrical electrolysis current to at least one electrolytic cell of the electrolysis device during normal operation in order to perform electrolysis of a substance located in a reaction chamber of the electrolytic cell, and detecting the electrical electrolysis current by a sensor unit. A protective voltage is applied to at least one electrolytic cell according to the detected electrical electrolysis current, which protective voltage is provided individually for the at least one electrolytic cell.

Claims

1. A circuit arrangement for at least one electrolytic cell of an electrolysis device, comprising: an electrical auxiliary voltage source which is designed to provide an electrical auxiliary DC voltage, connection contacts for electrical connection to cell connections of the at least one electrolytic cell, a protective voltage unit which is electrically coupled to the electrical auxiliary voltage source and is designed to provide an individual protective voltage for the at least one electrolytic cell, and a switching unit which is connected to the protective voltage unit and to the connection contacts and is designed to electrically couple the protective voltage unit for providing the protective voltage at the connection contacts to the connection contacts depending on a switching state of the switching unit.

2. The circuit arrangement as claimed in claim 1, wherein the switching unit comprises at least one individual switching element for each of the connection contacts.

3. The circuit arrangement as claimed in claim 1, wherein the protective voltage unit for providing the protective voltage comprises an electronic voltage converter electrically connected to the electrical auxiliary voltage source.

4. The circuit arrangement as claimed in claim 3, wherein the voltage converter is in the form of an in-phase regulator.

5. The circuit arrangement as claimed in claim 3, wherein the voltage converter has at least one diode and/or at least one electrical resistor which is used to provide the protective voltage.

6. The circuit arrangement as claimed in claim 1, further comprising: a sensor unit which is connected at least to the switching unit and is designed to capture an electrolysis current of the at least one electrolytic cell and to transmit a corresponding sensor signal at least to the switching unit.

7. An electrolysis device, comprising: at least one electrolytic cell and an electrolysis energy source connected to the at least one electrolytic cell, and a circuit arrangement as claimed in claim 1, which is connected to the at least one electrolytic cell.

8. The electrolysis device as claimed in claim 7, further comprising: a control unit which is designed to capture an operating state of the electrolysis energy source and to transmit a state signal to the circuit arrangement depending on the captured operating state, wherein the circuit arrangement is designed to provide a protective voltage for the at least one electrolytic cell depending on the state signal.

9. The electrolysis device as claimed in claim 7, further comprising: an isolating unit which is designed to electrically isolate the electrolysis energy source from the at least one electrolytic cell depending on a switching state of the isolating unit.

10. A method for operating an electrolysis device, comprising: applying an electrical electrolysis current to at least one electrolytic cell of the electrolysis device during intended operation in order to electrolyze a substance arranged in a reaction chamber of the electrolytic cell, capturing the electrical electrolysis current by a sensor unit, and applying a protective voltage, which is individually provided for the at least one electrolytic cell, to the at least one electrolytic cell depending on the captured electrical electrolysis current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the figures, identical reference signs denote identical features and functions.

[0037] In the figures:

[0038] FIG. 1 shows a schematic circuit diagram illustration of an electrolysis device having a plurality of electrolytic cells which are connected in series and are connected to an electrolysis energy source and an auxiliary energy source connected in parallel therewith;

[0039] FIG. 2 shows a schematic diagram illustration of a bath characteristic curve for an electrolytic cell of the electrolysis device according to FIG. 1, in which a cell voltage of the electrolytic cell is represented on the basis of an electrolysis current of the electrolytic cell;

[0040] FIG. 3 shows a schematic circuit diagram illustration, like FIG. 1, of an electrolysis device in which two diodes connected in series can be respectively connected in parallel with each individual electrolytic cell by means of switching elements which are provided with electrical energy by an auxiliary voltage source;

[0041] FIG. 4 shows a schematic circuit diagram illustration, like FIG. 3, in which the diodes are replaced with in-phase regulators, and

[0042] FIG. 5 shows a schematic circuit diagram illustration, like FIG. 4, in which the in-phase regulators are connected to the auxiliary voltage source in a parallel connection.

DETAILED DESCRIPTION OF INVENTION

[0043] FIG. 1 shows a schematic circuit diagram illustration of an electrolysis device 52 having a plurality of electrolytic cells 12 electrically connected in series. The electrolytic cells 12 are used to electrolyze water to form hydrogen and oxygen. In alternative configurations, a different substance may naturally also be subjected to the electrolysis here in order to convert this substance into corresponding other substances.

[0044] The electrolytic cells 12 connected in series are connected to a main rectifier 14 as an electrolysis energy source. The main rectifier 14 provides an operating voltage 50 which is applied to the series circuit of the electrolytic cells 12, with the result that an electrolysis current 48 flows through the electrolytic cells 12 during intended electrolysis operation.

[0045] A series circuit comprising a polarization rectifier 54 and a protective inductance 58 is connected as an auxiliary energy source, in parallel with the main rectifier 14, to the series circuit of the electrolytic cells 12. The polarization rectifier 54 and the protective inductance 58 are used to apply a rectifier voltage 68 to the electrolytic cells 12 outside intended electrolysis operation, which rectifier voltage is selected in such a manner that a protective current 56 is established, which protective current is in turn selected such that at least a polarization voltage U.sub.0 (FIG. 2) is applied to all electrolytic cells 12. This is intended to avoid undesirable processes in the electrolytic cells 12 outside intended electrolysis operation.

[0046] FIG. 2 shows a schematic diagram illustration of a diagram 60 in which an ordinate 62 is assigned to a cell voltage at respective cell connections 28 of an individual one of the electrolytic cells 12. An abscissa 64 is assigned to the corresponding cell current of this electrolytic cell 12. The dependence of the cell voltage on the cell current is represented using a graph 66. UN denotes an electrolysis voltage which is established at the electrolytic cell 12 during intended electrolysis operation if an electrolysis current 48 is applied to the electrolytic cell 12. A point of intersection of the graph 66 with the ordinate 62 defines the polarization voltage U.sub.0 which, when undershot, can result in a change in the polarization of the cell current.

[0047] In the present configuration of an electrolytic cell for the electrolysis of water, the electrolysis voltage is approximately 1.8 to 1.9 V. In the present configuration, the polarization voltage U.sub.0 may be approximately 1.48 V. In the case of a cell voltage which is greater than approximately 1.48 V, the electrolysis functionality begins at the electrolytic cell 12 by virtue of hydrogen and oxygen being produced.

[0048] The electrolysis device 52 proves to be disadvantageous insofar as gas production can still occur outside the actual electrolysis process or intended electrolysis operation. In this case, the result may be undefined states in the electrolysis device 52 which, in the worst case scenario, may even result in the production of an ignitable gas mixture. In order to ensure safety here, supplementary comprehensive protective measures are required.

[0049] FIG. 3 now shows an electrolysis device 10 in which the above-mentioned problems can be reduced, if not even completely avoided. The electrolysis device 10 is based on the electrolysis device 52 according to FIG. 1, which is why reference is additionally made to the relevant statements. In this case too, a series circuit comprising a plurality of electrolytic cells 12 is provided and is connected to the main rectifier 14 in a parallel manner in order to be supplied with electrical energy during 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 statements relating to FIGS. 1 and 2.

[0050] In contrast to the configuration according to FIG. 1, provision is made for the electrolysis device 10 according to FIG. 3 to have an electrical auxiliary voltage source 22 which is used to provide an electrical auxiliary DC voltage 24. The electrolysis device 10 also has a circuit arrangement 16 which is connected to the electrolytic cells 12.

[0051] The circuit arrangement 16 has the electrical auxiliary voltage source 22 which is used to provide an electrical auxiliary DC voltage 24. The circuit arrangement 16 also comprises connection contacts 26 for electrical connection to cell connections 28 of the electrolytic cells 12 of the series circuit. In the present configuration, provision is therefore made for all cell connections 28 to also be electrically coupled to the circuit arrangement 16.

[0052] The circuit arrangement 16 also has a protective voltage unit 34 which is electrically coupled to the electrical auxiliary voltage source 22. The protective voltage unit 34 provides, for each of the electrolytic cells 12, an individual protective voltage U.sub.s for the respective electrolytic cell 12.

[0053] The protective voltage U.sub.s (FIG. 2) is selected in such a manner that a fuel cell effect is not produced at any of the electrolytic cells 12, that is to say residual gases in a respective electrolysis 12 react to form water and thus release energy according to the fuel cell principle. This may result in considerable aging of a respective electrolytic cell 12.

[0054] The circuit arrangement 16 also has a switching unit 36 which is connected to the protective voltage unit 34 and to the connection contacts 26. The switching unit 36 is designed to electrically couple the protective voltage unit 34 for providing the protective voltage U.sub.s at the connection contacts 26 to the connection contacts 26 depending on a switching state of the switching unit 36. This makes it possible for the protective voltage unit 34 to need to be electrically connected to the electrolytic cells 12 only when this is necessary or desired on the basis of the operating situation of the electrolysis device 10. The protective voltage unit 34 can thus be deactivated with respect to the electrolytic cells 12 by means of the switching unit 36 if the electrolytic cells 12 are operated as intended in electrolysis operation.

[0055] The switching unit 36 therefore respectively has an individual switching element 38 for each of the connection contacts 26, which switching element is formed in the present case by a reed relay or reed contact. In alternative configurations, a corresponding relay or a contactor or an electronic switching element may naturally also be provided here.

[0056] The switching elements 38 are controlled together, in terms of their respective switching state, by a control unit 18 of the electrolysis device 10, with the result that all of the switching elements 38 each substantially assume the same switching state. For this purpose, the control unit 18 may comprise a control circuit which is also used, inter alia, to control the circuit arrangement 16.

[0057] In order to provide the protective voltage U.sub.s, the protective voltage unit 34 has an electronic voltage converter which is coupled to the electrical auxiliary voltage source 22 and, in the present case, is formed by a series circuit of diodes 44. Two diodes 44 connected in series in a manner immediately following one another are respectively electrically connected to a respective one of the electrolytic cells 12 in the switched-on switching state of the switching unit 36.

[0058] In the present case, the diodes 44 are formed by silicon diodes. This makes it possible to easily individually provide the desired protective voltage for each of the electrolytic cells 12. The protective voltage U.sub.s is less than the polarization voltage U.sub.0. Therefore, the power which needs to be provided by the circuit arrangement 16 can be considerably reduced in comparison with the electrolysis device 52 according to FIG. 1. At the same time, as a result of the fact that only a very small, in particular negligible, electrical current needs to be conducted through the electrolytic cells 12, the unfavorable evolution of gas is also reduced in comparison with the electrolysis device 52, if not even completely avoided.

[0059] In order to control the switching unit 36, provision is made in the present configuration for the cell current of the series circuit of the electrolytic cells 12 to be captured by means of a current sensor 46 as a sensor unit. The current sensor 46 delivers a corresponding sensor signal to the control unit 18 which evaluates this signal. As soon as the sensor signal is smaller than a predefined comparison value, the switching unit 36 is changed over from the switched-off switching state to the switched-on switching state. This means that the corresponding protective voltage U.sub.s is applied to each electrolytic cell 12 by the circuit arrangement 16 which is now activated as a result.

[0060] FIG. 4 shows a schematic circuit diagram illustration, like FIG. 3, of an alternative configuration of the electrolysis device 10. Only the differences from the configuration of the electrolysis device 10 according to FIG. 3 are explained below. The further features and functions correspond to those which have already been explained with respect to the electrolysis device 10 on the basis of FIG. 3.

[0061] In contrast to the configuration according to FIG. 3, the configuration according to FIG. 4 has a protective voltage unit 32 which has a voltage converter comprising in-phase regulators 42 connected in series. In the present case, the in-phase regulators 42 are adjustable and can be individually adjusted by the control unit 18 in terms of their respective protective voltage U.sub.s. The in-phase regulators 42 can be adjusted manually during maintenance or activation of the electrolysis device 10 or in the form of regulation by individually capturing respective cell voltages or operating states of the electrolytic cells 12 and using them for regulation, for example. Like in the configuration according to FIG. 3, the auxiliary DC voltage 24 is applied to the series circuit of the in-phase regulators 42 by the auxiliary voltage source 22.

[0062] FIG. 5 shows a further configuration for an electrolysis device 10 which is likewise based on the configuration of the electrolysis device 10 according to FIG. 3, which is why reference is likewise additionally made to the relevant statements. Only the differences are explained further below.

[0063] It is clear from FIG. 5 that a protective voltage unit 30 is provided and has, for each electrolytic cell 12, a respective voltage converter 40 which can be adjusted by means of the control unit 18, as already explained on the basis of the configuration according to FIG. 4. In the present configuration, the voltage converters 40 are connected to the auxiliary voltage source 22 in a parallel manner and the auxiliary DC voltage 24 is applied to them by the auxiliary voltage source. The voltage converters 40 are adjusted in such a manner that the respective individual protective voltage U.sub.s can be provided for each of the electrolytic cells 12.

[0064] In this configuration, provision is made for the voltage converters 40 to be formed by a clocked voltage converter in the form of a DC/DC converter. In alternative configurations, an in-phase regulator, like the in-phase regulator 42 according to FIG. 4, may naturally likewise also be provided here.

[0065] In addition, provision is made in the present case for the main rectifier 14 to be able to be electrically isolated from the electrolytic cells 12 via an isolating unit 20 which is in the form of a contactor in the present case. This is advantageous if the main rectifier 14 has a fault which may result, for example, in a short circuit or the like. If the electrolysis device 10 is not in intended electrolysis operation, the isolating unit 20 may be switched to the switched-off state by means of the control unit 18, with the result that the main rectifier 14 is electrically isolated from the electrolytic cells 12. In a particularly advantageous manner, locking may be provided by means of the control unit 18 in such a manner that either only the switching unit 36 or the isolating unit 20 is in the switched-on switching state.

[0066] The exemplary embodiments are used solely to explain the invention and are not intended to restrict the latter.