Electrolysis device, system consisting of a plurality of electrolysis devices, and method for operating the electrolysis device or the system

Abstract

The invention relates to an electrolysis device (10) for generating hydrogen from water using an electric current, having a cell stack (11) comprising a plurality of cell stack elements (12) in the form of electrolysis cells; a first pressure sensor (28) for detecting a first hydrogen-side pressure; a second pressure sensor (29) for detecting a second hydrogen-side pressure; and a control device (30) which checks whether the electrolysis device (10) has a leak on the basis of the first pressure measured by the first pressure sensor (28), the second pressure measured by the second pressure sensor (29), and the electric current applied to the electrolysis device (10) for the electrolysis process.

Description

[0001] Quest One GmbH

[0002] Electrolysis device, system comprising several electrolysis devices and method for operating the electrolysis device or the system

[0003] The invention relates to an electrolysis device and a method for operating the same. Furthermore, the invention relates to a system comprising a plurality of electrolysis devices and a method for operating the same.

[0004] DE 10 2017 108 413 A1 discloses an electrolysis device with a cell stack (“stack”) composed of a plurality of cell stack elements. Furthermore, the electrolysis device known from this prior art comprises a force application unit, via which a force can be exerted on the cell stack in order to press the cell stack elements of the cell stack together in a fluid-tight manner. The force application unit comprises opposing end plates, between which the cell stack is arranged and pressed together. Furthermore, the force application unit comprises pressing devices comprising spring elements and struts, wherein the spring force of the spring elements presses the end plates against one another, pressing the cell stack together. Connections are formed on the end plates of the electrolysis device, namely water supply connections, water discharge connections, and hydrogen connections.Corresponding lines, namely at least one water supply line, one water drain line, and one hydrogen line, are connected to these connections via coupling devices. Water is supplied to the electrolysis device via the water supply connections, and water and oxygen are removed from the electrolysis device via the water drain connections. The hydrogen connections are used to remove the hydrogen produced during electrolysis. If several electrolysis devices are connected in series to form a cascade, hydrogen can be supplied to an electrolysis device via a hydrogen connection for passage through the electrolysis device from an electrolysis device positioned upstream. Although the cell stack of an electrolysis device is pressed together in a fluid-tight manner via its force application unit, leaks can develop in an electrolysis device through which hydrogen can be lost.On the one hand, this reduces the efficiency of the electrolysis device, and on the other hand, uncontrolled loss of hydrogen represents a source of danger.

[0005] In practice, hydrogen leak detection is achieved by using a hydrogen sensor to interact with several electrolysis devices arranged in a so-called stack chamber and interconnected to form a system of multiple electrolysis devices. If the hydrogen sensor in the stack chamber measures an unacceptably high hydrogen concentration, it is concluded that there is a leak in one or more electrolysis devices. In this case, the entire system must be shut down.

[0006] There is a need to detect a leak in an electrolysis device or in a system comprising multiple electrolysis devices without the need for a hydrogen sensor, particularly individually for each respective electrolysis device. Based on this, the present invention is based on the object of creating a novel electrolysis device, a system comprising such electrolysis devices, and a method for operating the same. This object is achieved by an electrolysis device according to claim 1, by a system comprising multiple electrolysis devices according to claim 10, and by a method according to claim 11.

[0007] According to the invention, the first pressure sensor of the electrolysis device serves to measure a first hydrogen-side pressure, and the second pressure sensor of the electrolysis device serves to measure a second hydrogen-side pressure on the electrolysis device according to the invention. According to the invention, the control unit checks whether the electrolysis device is leaking depending on the first pressure measured by the first pressure sensor, the second pressure measured by the second pressure sensor, and the electrical current applied to the electrolysis device for electrolysis or another production parameter of the electrolysis device.

[0008] Leakage testing can be understood as the control unit performing a calculation to calculate an indicator value that represents a measure of the presence of a leak. The measure of the leak can be digital (tight vs. leaky) or continuous (degree of leakage, such as a percentage loss of pressure or volume).

[0009] The electrolysis device according to the invention uses differential pressure measurement to detect leaks. Depending on the pressures measured by the pressure sensors, a leak (or a degree of leak) can be determined individually for each electrolysis device without the need for a hydrogen sensor. This allows for simple and reliable detection of leaks in an electrolysis device without the need for a hydrogen sensor, specifically for each electrolysis device.

[0010] If a leak is detected, it is no longer necessary to shut down an entire system comprising several electrolysis devices; instead, each electrolysis device or group (cascade) of electrolysis devices can be shut down individually.

[0011] In particular, the first pressure sensor is assigned to a first hydrogen connection of the electrolysis device, preferably formed on a first end plate, via which hydrogen is discharged from the electrolysis device during operation, or to a hydrogen line coupled to the first hydrogen connection, or to a respective coupling device. The second pressure sensor is assigned to a second hydrogen connection of the electrolysis device, preferably formed on a second end plate opposite the first end plate, via which no hydrogen is discharged from the electrolysis device during operation, or to a hydrogen line coupled to the second hydrogen connection, or to a respective coupling device. This is preferred for the simple and reliable detection of leaks in an electrolysis device. The end plates can be end plates of the same cell stack of the electrolysis device.However, the end plates can also be end plates of different cell stacks of the electrolysis device.

[0012] Preferably, the control unit forms an actual pressure difference from the first pressure and the second pressure and checks whether the electrolysis device has a leak depending on the actual pressure difference and a production parameter, the electrical current applied for electrolysis, preferably by calculating an indicator value as a measure of leakage and, if necessary, forwarding it to a higher-level control or display. This is preferred for the simple and reliable detection of leaks in an electrolysis device. In particular, a characteristic curve for a target pressure difference is stored in the control unit depending on the electrical current applied for electrolysis, wherein the control unit compares the actual pressure difference dependent on the applied electrical current with a target pressure difference dependent on the applied electrical current and, depending on this, checks whether the electrolysis device has a leak.This is particularly preferred for the simple and reliable detection of leaks in an electrolysis device. Alternatively or additionally, however, other equivalent production parameters could also be used to provide a reference in the form of a target pressure difference, in order to then compare the determined actual pressure difference with a target pressure difference and, based on this, to detect a leak. Equivalent production parameters can be, for example, volume flows of hydrogen and / or water in the electrolysis device or a voltage applied to the electrolysis device or a voltage drop across the electrolysis device or a part of the electrolysis device. Preferably, the first hydrogen connection and the second hydrogen connection are hydrogen connections that have a maximum geometric distance from one another.This allows the pressure difference to be measured particularly advantageously.

[0013] Preferably, the first hydrogen connection or the hydrogen line coupled to the first hydrogen connection or the respective coupling device via which the first hydrogen line is coupled to the first hydrogen connection is assigned a throttle which is preferably switchable by the control unit such that the control unit transfers the throttle into a first switching state for the leak test and then into a second switching state, wherein the throttle is wider open in the second switching state than in the first switching state. Preferably, the throttle is fully open in the second switching state. By means of a throttle, it is possible to increase the pressure loss and thus improve the measurement accuracy. Since an increase in the pressure loss via a throttle is undesirable per se, it is proposed to close the throttle only for measurement and otherwise to open the throttle as fully as possible.

[0014] Preferred developments of the invention will become apparent from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein:

[0015] Fig. 1 is a schematic representation of an electrolysis device according to the invention,

[0016] Fig. 2 shows a schematic representation of a cascade of several electrolysis devices according to the invention connected in series. Fig. 1 shows a schematic view of an electrolysis device 10. In such an electrolysis device 10, hydrogen H2 and oxygen O2 are obtained from the water H2O via the electrolysis of water H2O using electrical energy.

[0017] The electrolysis device 10 shown in Fig. 1 has a cell stack 11 composed of a plurality of cell stack elements 12, namely a plurality of electrolysis cells. The cell stack 11, composed of the plurality of cell stack elements 12, is pressed together in a fluid-tight manner by a force application unit 13. The force application unit 13 has end plates 14, 15 between which the cell stack 11 is arranged and pressed. In order to press the cell stack 11 between the end plates 14, 15, the force application unit 13 further has a pressing device (not shown).

[0018] As already explained, the electrolysis device 10 serves to produce hydrogen H2 from water H2O. Oxygen O2 is also produced in the process. The electrolysis device 10 has water connections through which, on the one hand, water H2O can be supplied to the electrolysis device 10 and, on the other hand, water H2O can be discharged from the electrolysis device 10 together with the separated O2.

[0019] In Fig. 1, water supply connections 17 are shown in the area of ​​the end plate 14 and water discharge connections 18 are shown in the area of ​​the end plate 15. The water supply connections 17 serve to supply water H2O to the electrolysis device 10. The water discharge connections 18 serve to discharge water H2O from the electrolysis device 10. The water supply connections 17 can be connected to at least one water supply line 16, and the water discharge connections 18 can be connected to at least one water discharge line 19 via a respective coupling device 20, 21. Oxygen O2 is also discharged together with water H2O via the water discharge connections 18 and water discharge line 19, respectively, so that no separate gas connections are required for the discharge of the oxygen O2. Alternatively, separate gas connections can also be provided for the discharge of the oxygen O2.

[0020] In the area of ​​the end plates 14, 15 of the same cell stack, hydrogen connections 22, 23 are also shown. In the exemplary embodiment shown, hydrogen connections 22, 23 are formed on both end plates 14, 15. In Fig. 1, a first hydrogen connection 23 formed on the end plate 15 serves to remove the hydrogen H2 obtained during electrolysis from the electrolysis device 10. Furthermore, in Fig. 2, the at least one second hydrogen connection 22 formed on the end plate 14 is closed, and accordingly, no hydrogen H2 can be removed from the electrolysis device 10 via this connection in Fig. 1.

[0021] If, as shown in Fig.2, several electrolysis devices 10 are connected in series to form a cascade 33, hydrogen can be supplied to an electrolysis device 10 via the at least one hydrogen connection 22 formed on the end plate 14 for passage therethrough from an electrolysis device 10 positioned in front of it.

[0022] The hydrogen connections 22, 23 can be connected to at least one hydrogen line 24, 25 via a respective coupling device 26, 27.

[0023] As already explained, the force application unit 13 has the two end plates 14, 15 and the pressing device (not shown), wherein the end plates 14, 15 can be pressed together in a fluid-tight manner by means of the pressing device, while the cell stack 11 is compressed between the end plates 14, 15. According to the invention, a first hydrogen-side pressure can be detected or measured via a first pressure sensor 28 and a second hydrogen-side pressure can be detected or measured at the electrolysis device 10 via a second pressure sensor 29. A control unit 30 checks whether the electrolysis device 10 is leaking depending on the first pressure measured by the first pressure sensor 28, the second pressure measured by the second pressure sensor 29 and the electrical current applied to the electrolysis device 10 for the electrolysis.

[0024] Preferably, the first pressure sensor 28 is associated with the first hydrogen connection 23 of the end plate 15, via which the hydrogen is discharged from the electrolysis device 10 during operation of the electrolysis device 10, or with the hydrogen line 25 coupled to the first hydrogen connection 23 or with the respective coupling device 25.

[0025] The second pressure sensor 29 is preferably associated with the second hydrogen connection 22 of the end plate 15, via which no hydrogen is discharged from the electrolysis device 10 during operation of the electrolysis device 10, or with the hydrogen line 24 coupled to the second hydrogen connection 22 or with the respective coupling device 26.

[0026] The control unit 30 checks whether the electrolysis device 10 is leaking based on the first pressure measured by the first pressure sensor 28, the second pressure measured by the second pressure sensor 29, and the electrical current applied to the electrolysis device 10 for electrolysis. Thus, it is possible to check individually for an electrolysis device 10 whether the electrolysis device 10 is leaking hydrogen without the need for a hydrogen sensor.

[0027] Preferably, the control unit 30 forms an actual pressure difference from the first pressure and the second pressure. The control unit 30 then checks, depending on the actual pressure difference and the electrical current applied to the electrolysis device 10 for electrolysis, whether the electrolysis device 10 is leaking. This is preferably done in such a way that a characteristic curve for a target pressure difference is stored in the control unit 30 depending on the electrical current applied for electrolysis. The control unit 30 compares the actual pressure difference dependent on the electrical current with the target pressure difference dependent on the electrical current applied. If the actual pressure difference deviates from the target pressure difference by an inadmissible amount, a leak in the electrolysis device 10 is concluded.

[0028] If, for example, the deviation between the actual pressure difference and the target pressure difference is greater than a first limit value and less than a second limit value, it is concluded that there is a hydrogen leak, but the leak is small enough to allow continued operation of the electrolysis device 10. If, however, the deviation between the actual pressure difference and the target pressure difference is greater than the second limit value, the electrolysis device 10 is preferably shut down. If the deviation between the actual pressure difference and the target pressure difference is less than the first limit value, it is concluded that there is no leak in the electrolysis device 10.

[0029] The characteristic curve dependent on the electrical current, which is stored in the control unit 30, is preferably determined empirically and stored in a memory of the control unit 30. A processor of the control unit 30 can determine the actual pressure difference and compare it with the desired pressure difference. The control unit 30 can receive the pressures measured by the pressure sensors 28, 29 via data interfaces. Via another data interface, the control unit 30 can then issue a warning message or shut down the electrolysis device 10 if a leak is detected.As the first hydrogen connection 23, to which the first pressure sensor 28 is operatively connected directly or indirectly via the hydrogen line 25 or the coupling device 27, and as the second hydrogen connection 22, to which the second pressure sensor 29 is operatively connected directly or indirectly via the hydrogen line 24 or the coupling device 26, those hydrogen connections 22, 23 of the electrolysis device 10 are preferably used which have a maximum geometric distance from one another on the electrolysis device 10, i.e. which are spaced or removed from one another as far as possible.

[0030] Thus, the first and second hydrogen connections 22, 23 are preferably assigned to different end plates 14, 15, preferably diagonally opposite each other. While a hydrogen connection positioned in a lower left corner is used as the first hydrogen connection 23 on the end plate 15, a hydrogen connection positioned in an upper right corner of the end plate 14 is used as the second hydrogen connection 22 on the opposite end plate 14.

[0031] The maximum geometric distance between the first and second hydrogen connection can increase the resulting pressure drop and thus the sensitivity of the differential pressure measurement.

[0032] It can be provided that a throttle 31 is assigned to the first hydrogen connection 23 or to the hydrogen line 25 coupled to the first hydrogen connection 23 or to the respective coupling device 27. The throttle 31 is preferably switchable by the control unit 30, namely in such a way that the control unit 30 transfers the throttle 31 to a first switching state for the leak test and then to a second switching state. In the second switching state, which the throttle 31 assumes outside of a leak test, the throttle is wider open than in the first state, preferably completely. Thus, in this development of the invention, a pressure loss via the throttle 31 only builds up when a leak test is actually to be carried out.

[0033] The invention further relates to a method for operating an electrolysis device 10 according to the invention. The method according to the invention comprises at least the following steps: Measuring a first pressure with the first pressure sensor 28. Measuring a second pressure with the second pressure sensor 29. Determining an actual pressure difference between the first pressure and the second pressure. Checking the tightness of the electrolysis device 10 as a function of the actual pressure difference and the electrical current applied to the electrolysis device 10 for electrolysis. As already explained, the tightness of the electrolysis device 10 is determined as a function of the determined actual pressure difference in such a way that the actual pressure difference is compared with a target pressure difference dependent on the applied current, and the tightness test of the electrolysis device 10 is carried out as a function of this comparison.

[0034] Then, the throttle 31 is assigned to the first hydrogen connection 23 or to the hydrogen line 25 coupled to the first hydrogen connection 23 or to the respective coupling device 27, the throttle 31 is only transferred to the first switching state when the first pressure is measured to check the tightness of the electrolysis device 10.

[0035] Although in the embodiment shown in Fig. 1 the pressure sensors 28, 29 are assigned to the hydrogen connections 22, 23 or to the hydrogen lines 24, 25 coupled to the hydrogen connections 22, 23 or to the respective coupling devices 26, 27, it is also possible to assign the pressure sensors 28, 29 to individual cell stack elements 12 of the cell stack 11 of a respective electrolysis device 10. In this case, the leakage with respect to individual cell stack elements 12 can then be checked. The invention further relates to a system comprising a plurality of electrolysis devices 10. Fig. 2 shows a system 32 comprising a plurality of electrolysis devices 10 connected in series to form a cascade 33. In such electrolysis devices 10 connected in series to form a cascade 33, water and hydrogen are passed sequentially through the electrolysis devices 10 combined to form a cascade 33. Fig.Figure 2 shows a pump 34 for pumping water through the electrolysis devices 10. Furthermore, Figure 2 shows a hydrogen collection container 35 for collecting the hydrogen generated in the electrolysis devices 10.

[0036] In the system 32 of Fig. 2, each of the electrolysis devices 10 shown is assigned a first pressure sensor 28 and a second pressure sensor 29. Thus, an actual pressure difference can be determined individually for each of the electrolysis devices 10 and compared by the control unit 30 with a corresponding target pressure difference in order to individually test all electrolysis devices 10 for hydrogen leaks.

[0037] It is also possible for the control device 30 to determine a pressure difference between the pressure measured at the right electrolysis device 10 shown in Fig. 1 using the first pressure sensor 28 and the pressure measured at the left electrolysis device 10 shown in Fig. 2 using the pressure sensor 29. In this case, it can then be checked whether a hydrogen leak exists for the cascade 33.

[0038] A system according to the invention comprising electrolysis devices 10 can also comprise parallel-connected electrolysis devices 10 or parallel-connected cascades 33 each comprising a plurality of series-connected electrolysis devices 10.

[0039] The invention further relates to a method for operating a system comprising a plurality of electrolysis devices 10. Thus, a first pressure is measured using at least one first pressure sensor 28, and a second pressure is measured using at least one second pressure sensor 29, and the values ​​are provided to the control unit 30. The control unit 30 then determines a respective actual pressure difference and compares the respective actual pressure difference with a desired pressure difference, which are each dependent on the electrical current applied for electrolysis, in order to detect a hydrogen leak individually at an electrolysis device 10 or at a cascade of a plurality of electrolysis devices 10 connected in series.

[0040] List of reference symbols

[0041] 10 Electrolysis device

[0042] 11 cell stacks

[0043] 12 cell stack element

[0044] 13 Force application unit

[0045] 14 End plate

[0046] 15 End plate

[0047] 16 Water supply line

[0048] 17 Water supply connection

[0049] 18 Water drainage connection

[0050] 19 Water drainage

[0051] 20 Coupling device

[0052] 21 Coupling device

[0053] 22 Hydrogen connection

[0054] 23 Hydrogen connection

[0055] 24 Hydrogen pipeline

[0056] 25 Hydrogen pipeline

[0057] 26 Coupling device

[0058] 27 Coupling device

[0059] 28 first pressure sensor

[0060] 29 second pressure sensor

[0061] 30 Control unit

[0062] 31 Throttle

[0063] 32 systems

[0064] 33 Cascade

[0065] 34 Pump

[0066] 35 collection containers

Claims

Claims 1. Electrolysis device (10) for generating hydrogen from water with the aid of electrical current, with a cell stack (11) made up of a plurality of cell stack elements (12) designed as electrolysis cells, characterized by a first pressure sensor (28) for detecting a first hydrogen-side pressure, a second pressure sensor (29) for detecting a second hydrogen-side pressure, a control device (30) which checks whether the electrolysis device (10) is leaking depending on the first pressure measured by the first pressure sensor (28), depending on the second pressure measured by the second pressure sensor (29) and depending on a production parameter, in particular the electrical current and / or the electrical voltage applied to the electrolysis device (10) for electrolysis.

2. Electrolysis device (10) according to claim 1, characterized by opposing end plates (14, 15), wherein the cell stack (11) comprising the cell stack elements (12) is arranged and pressed between the end plates (14, 15), water supply connections (17), water discharge connections (18) and hydrogen connections (22, 23) formed on the end plates (14, 15), wherein the water supply connections (17) are connectable to at least one water supply line (16), the water discharge connections (18) are connectable to at least one water discharge line (19), and the hydrogen connections (22, 23) are connectable to at least one hydrogen line (24, 25) via a respective coupling device (20, 25, 26), wherein the first pressure sensor (28) is connected to a first hydrogen connection (23), via which hydrogen is discharged from the electrolysis device, or to a first hydrogen connection (23) coupled hydrogen line (25) or a respective coupling device (27) is arranged, wherein the second pressure sensor (29) is assigned to a second hydrogen connection (22), via which no hydrogen is discharged from the electrolysis device, or to a hydrogen line (24) coupled to the second hydrogen connection (22) or to a respective coupling device (26).

3. Electrolysis device (10) according to claim 1 or 2, characterized in that the control device (30) forms an actual pressure difference from the first pressure and the second pressure and checks whether the electrolysis device (10) has a leak depending on the actual pressure difference and the electrical current applied for the electrolysis.

4. Electrolysis device (10) according to claim 3, characterized in that a characteristic curve for a desired pressure difference is stored in the control unit (30) depending on the electrical current applied for electrolysis, wherein the control unit (3) compares the actual pressure difference dependent on the applied electrical current with a desired pressure difference dependent on the applied electrical current and, depending thereon, checks whether the electrolysis device (10) has a leak.

5. Electrolysis device (10) according to one of claims 1 to 4, characterized in that as the first hydrogen connection (22) and as the second hydrogen connection (23) such hydrogen connections are used which have a maximum geometric distance from one another on the electrolysis device (10).

6. Electrolysis device (10) according to one of claims 1 to 4, characterized in that the first hydrogen connection (22) and the second hydrogen connection (23) are formed on different end plates (14, 15) of the same cell stack (11) or on different end plates (14, 15) of different cell stacks (11).

7. Electrolysis device (10) according to one of claims 1 to 6, characterized in that an adjustable throttle (31) for throttling the hydrogen flow is assigned to the first hydrogen connection (23) or to the hydrogen line (25) coupled to the first hydrogen connection (23) or to the respective coupling device (27) via which the first hydrogen line (25) is coupled to the first hydrogen connection (23).

8. Electrolysis device (10) according to claim 7, characterized in that the throttle (31) can be switched by the control device (30).

9. Electrolysis device (10) according to claim 8, characterized in that the control device (30) transfers the throttle (31) for the leak test into a first switching state and then into a second switching state, wherein the throttle (31) is further open in the second switching state than in the first switching state.

10. System comprising a plurality of electrolysis devices (10) according to one of claims 1 to 9, characterized in that when a plurality of electrolysis devices (10) are connected in series to form a cascade (33), the control device (30) measures the actual pressure difference across the cascade to check for leaks in the cascade. kade (33), and / or the control unit (30) determines the actual pressure difference for each electrolysis device (10) individually to check for an individual leak in the respective electrolysis device (10), then, if electrolysis devices (10) are connected in parallel, the control unit (30) determines the actual pressure difference for each electrolysis device (10) individually to check for a leak.

11. A method for operating an electrolysis device (10) according to one of claims 1 to 9, or for operating a system comprising a plurality of electrolysis devices (10) according to claim 10, comprising the following steps: Measuring a first pressure with the first pressure sensor (28), measuring a second pressure with the second pressure sensor (29), determining an actual pressure difference between the first pressure and the second pressure; Checking the tightness of the electrolysis device (10) or the cascade (33) depending on the actual pressure difference and an electric current applied to the electrolysis device (10) or to the cascade (33) for electrolysis.

12. The method according to claim 11, characterized in that the tightness is checked as a function of the actual pressure difference in such a way that the actual pressure difference is compared with a desired pressure difference which is dependent on the applied electric current and the tightness of the electrolysis device (10) or the cascade (33) is checked as a function of this.

13. The method according to claim 11 or 12, characterized in that when a throttle (31) is assigned to the first hydrogen connection (23) or to the hydrogen line (25) coupled to the first hydrogen connection (23) or to the respective coupling device (27), the throttle (31 ) is only transferred to the first switching state when the first pressure is measured to check the tightness.

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