Diagnostic method for diagnosing the state of an electrolysis system, and electrolysis system

Abstract

The invention relates to a diagnostic method (100) for diagnosing the state of an electrolysis system (200), which comprises a plurality of cell stacks (201, 207). The diagnostic method (100) has the steps of determining (101) a plurality of pressure differences between a respective stack-specific cathode pressure in a cathode outlet path (203, 209) of a cathode sub-system of each cell stack (201, 207) of the plurality of cell stacks (201, 207) and an anode pressure in an anode outlet path (205, 211) downstream, in the flow direction, of a first connection point (221), at which all of the anode outlet paths (205, 211) of each anode sub-system of the number of cell stacks (201, 207) are combined, and outputting (103) a cell stack-specific reaction request in the event that a pressure difference between a respective stack-specific cathode pressure and the anode pressure deviates from a specified diagnostic threshold value, wherein the reaction request includes information regarding in which cell stack (201, 207) of the plurality of cell stacks (201, 207) the pressure difference deviates from the diagnostic threshold value.

Description

[0001] Description

[0002] Title and

[0003] The presented invention relates to a diagnostic method for diagnosing a condition of an electrolysis system, an electrolysis system and a program product according to the appended claims.

[0004] State of the art

[0005] One possible technology for producing green hydrogen through electrolysis is so-called PEM (proton exchange membrane) electrolysis systems. In addition to PEM, other possible technologies include AEM (anion exchange membrane), SOEC (solid oxide electrolysis), and liquid alkaline systems.

[0006] When using PEM and AEM electrolysis systems in particular, a pressure difference is often generated between the anode and cathode for various systemic reasons.

[0007] In addition, in larger electrolysis systems and with limited cell stack size, it is common for several cell stacks to be hydraulically connected in parallel in an electrolysis system, regardless of the type of electrical connection.

[0008] The various cell stacks can be connected to shared components, such as a gas-liquid separator. For safety reasons, it is necessary to monitor the pressure downstream of the cell stacks. Since the anode and cathode subsystems of each cell stack typically contain check valves that fluidically decouple different line sections, it may happen that a pressure change in a particular area is not detected or is calculated incorrectly.

[0009] Disclosure of the invention

[0010] Within the scope of the invention presented, an electrolysis system and a diagnostic method for diagnosing the condition of the electrolysis system, as well as a program product, are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the diagnostic method according to the invention naturally also apply in connection with the electrolysis system according to the invention or the program product according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0011] The invention presented serves in particular to provide a possibility for the safe operation of an electrolysis system.

[0012] Thus, according to a first aspect of the invention presented, a diagnostic method for diagnosing a condition of an electrolysis system comprising a plurality of cell stacks is presented.

[0013] The presented diagnostic method comprises determining a plurality of pressure differences between a respective stack-specific cathode pressure in a cathode outlet path of a cathode subsystem of each cell stack of the plurality of cell stacks and an anode pressure in an anode outlet path in the flow direction after a connection point at which all anode outlet paths of respective anode subsystems of the plurality of cell stacks are brought together, and issuing a cell stack-specific reaction request in the event that a pressure difference between a respective stack-specific cathode pressure and the anode pressure deviates from a predetermined diagnostic threshold value, wherein the reaction request comprises information about the cell stack of the plurality of cell stacks for which the pressure difference deviates from the diagnostic threshold value.

[0014] The presented invention is based on determining a plurality of stack-specific pressure differences. This means that each cell stack of an electrolysis system is assigned a specific pressure difference, and based on a plurality of specific pressure differences, specific monitoring or specific diagnosis of each individual cell stack of an electrolysis system with multiple cell stacks is achieved.

[0015] The stack-specific pressure difference is based on a stack-specific cathode pressure measured in a cathode outlet path of a cathode subsystem of a respective cell stack. In particular, the cathode pressure is measured upstream of a point where the cathode outlet path of a respective cell stack flows into a manifold or can be changed via an actuator, such as a check valve. Accordingly, a respective cathode pressure, particularly supplemented by information on the anode pressure, such as a pressure at the anode outlet, represents a state of a respective cell stack, so that the state of the respective cell stack can be deduced from the respective cathode pressure.

[0016] In order to detect a faulty state of a respective cell stack, it is provided that the respective cathode pressures are considered in relation to the anode pressure, ie, an anode outlet pressure or a reference value which is the same for all cell stacks or cathode pressures.

[0017] By comparing a respective pressure difference based on a stack-specific cathode pressure and a global anode outlet pressure with a diagnostic threshold, a tolerance band is specified within which a deviation of a cathode pressure from the anode pressure is acceptable, and outside of which a faulty condition exists. For this purpose, the diagnostic threshold can, for example, comprise several characteristic values, a range, or a deviation.

[0018] Accordingly, it is provided that if a pressure difference between a respective stack-specific cathode pressure and the anode pressure deviates from a predetermined diagnostic threshold, a response request is issued. This means that the response request is displayed, for example, on an output unit, in particular a screen, and / or stored in a memory, such as an error memory of an electrolysis system.

[0019] Depending on the response requirement, which may include, for example, a stack-specific error message or a stack-specific validation message, further functions of the electrolysis system can be triggered to enable safe plant operation or to activate emergency operation of the electrolysis system if an error message is issued for at least one cell stack.

[0020] Furthermore, depending on the reaction requirement, further reactions or settings of the electrolysis system can be carried out, such as a process control that controls process variables in such a way that a violation of the threshold values ​​is counteracted, a safety control that transfers the electrolysis system to a safe state, e.g. switches it off, if safety-relevant threshold values ​​are violated.

[0021] It can be provided that determining the pressure difference comprises measuring a number of cathode pressures using respective cathode pressure sensors arranged in a cathode outlet path of a cathode subsystem of each cell stack of the plurality of cell stacks, and measuring an anode pressure using an anode pressure sensor arranged in an anode outlet path in the flow direction downstream of a connection point at which all anode outlet paths of respective anode subsystems of the plurality of cell stacks are converged. By separately measuring respective cathode pressures using separate cathode pressure sensors, the respective measurements can be clearly and easily assigned to a respective cell stack, for example by storing an assignment scheme that assigns respective cathode pressure sensors to respective cell stacks in a computing unit or a memory.

[0022] By measuring a central or global anode pressure in an anode outlet path downstream of a junction where all anode outlet paths of the respective anode subsystems of the multiple cell stacks converge, a central reference is provided that is consistent across all cell stacks. Accordingly, differential pressures referenced based on the anode pressure are comparable.

[0023] It can further be provided that determining the pressure difference comprises measuring the anode pressure, such as the anode outlet pressure, by means of a differential pressure sensor which is configured to determine a differential pressure between a respective cathode pressure in the flow direction after a second connection point, at which all cathode outlet paths of respective cathode subsystems of the plurality of cell stacks are brought together, and the anode pressure in the anode outlet path in the flow direction after the first connection point.

[0024] By using a differential pressure sensor to determine the reference or anode pressure in relation to a global cathode pressure, the operating state of the electrolysis system is taken into account particularly validly when determining the pressure difference.

[0025] Furthermore, a differential pressure sensor that measures a differential pressure between a first point in the anode subsystem, located downstream of a second connection point where all anode outlet paths connect, and a second point in the cathode subsystem, located downstream of a first connection point where all cathode outlet paths connect, allows a stack-specific anode pressure to be calculated by relating it to a respective stack-specific cathode pressure. It can further be provided that when measuring a respective cathode pressure, at least the corresponding cathode outlet path is fluidically decoupled from a downstream pressure source.

[0026] A fluidic decoupling of a respective cathode outlet path from a downstream pressure source, such as a gas-liquid separator, excludes external influences from outside a respective cell stack or electrolysis system on the measurement of the stack-specific cathode pressure.

[0027] For fluidic decoupling of a respective cathode outlet path from a downstream pressure source, a check valve can be used, for example, in the flow direction after a measuring point at which the cathode pressure is measured and before a point at which the cathode outlet path flows into further lines.

[0028] Accordingly, it can further be provided that when measuring the anode pressure, all anode outlet paths are fluidically decoupled from a downstream pressure source.

[0029] Fluidic decoupling of the anode outlet path from a downstream pressure source, such as a gas-liquid separator, eliminates external influences from the anode subsystem on the anode pressure measurement.

[0030] For fluidic decoupling of the anode outlet path from a downstream pressure source, a check valve can be used, for example, in the flow direction after a measuring point at which the global anode pressure is measured and before a point at which the anode outlet path flows into further lines.

[0031] Accordingly, it can also be provided that, when measuring the cathode pressure, all cathode outlet paths are fluidically decoupled from a downstream pressure source. According to a second aspect, the presented invention relates to an electrolysis system for converting energy.

[0032] The presented electrolysis system comprises a plurality of cell stacks and a computing unit, wherein the computing unit is configured to carry out a possible embodiment of the presented diagnostic method.

[0033] The presented diagnostic procedure is particularly used for the robust operation of the presented electrolysis system.

[0034] It can be provided that the electrolysis system further comprises a plurality of cathode pressure sensors, wherein respective cathode pressure sensors of the plurality of cathode pressure sensors are configured to measure a stack-specific cathode pressure in a cathode outlet path of a cathode subsystem of a respective cell stack of the plurality of cell stacks, and an anode pressure sensor, wherein the anode pressure sensor is configured to measure an anode pressure in an anode outlet path in the flow direction after a connection point at which all anode outlet paths of respective anode subsystems of the plurality of cell stacks are brought together.

[0035] Separate cathode pressure sensors for measuring the respective cathode pressures enable a simple and quick assignment of a particular cathode pressure to a particular cell stack. Accordingly, the respective cell stacks can be monitored and diagnosed particularly quickly, especially in parallel.

[0036] It can further be provided that the electrolysis system further comprises a differential pressure sensor, wherein the differential pressure sensor is configured to determine a differential pressure between a respective cathode pressure in the flow direction downstream of a second connection point, at which all cathode outlet paths of respective cathode subsystems of the plurality of cell stacks are converged, and the anode pressure in the anode outlet path in the flow direction downstream of the first connection point. According to a third aspect, the presented invention relates to a program product, wherein the program product comprises program code means which, when the program product is executed on a computing unit, configure the computing unit to execute a possible embodiment of the presented diagnostic method.

[0037] In the context of the invention presented, a computing unit is understood to mean a computer, a processor, a control unit or any other programmable circuit.

[0038] Advantages described in detail with respect to the diagnostic method for diagnosing a condition of an electrolysis system according to the first aspect of the invention equally apply to the electrolysis system for converting energy according to the second aspect of the invention and the program product according to the third aspect of the invention.

[0039] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0040] They show schematically:

[0041] Figure 1 shows a possible design of the presented diagnostic procedure,

[0042] Figure 2 shows a first possible design of the electrolysis system presented, and

[0043] Figure 3 shows a second possible design of the presented electrolysis system.

[0044] Fig. 1 illustrates a diagnostic method 100 for diagnosing a condition of an electrolysis system comprising a plurality of cell stacks. The diagnostic method 100 comprises a determination step 101 in which a plurality of pressure differences between a respective stack-specific cathode pressure in a cathode outlet path of a cathode subsystem of each cell stack of the plurality of cell stacks and an anode pressure in an anode outlet path in the flow direction downstream of a junction at which all anode outlet paths of respective anode subsystems of the plurality of cell stacks are converged are determined, and an output step 103 in which a cell stack-specific response request is output in the event that a pressure difference between a respective stack-specific cathode pressure and the anode pressure deviates from a predetermined diagnostic threshold.

[0045] It can be provided that the reaction request includes information about which cell stack of the plurality of cell stacks the pressure difference deviates from the diagnostic threshold value.

[0046] Furthermore, depending on the reaction requirement, further reactions or settings of the electrolysis system can be carried out, such as a process control that controls process variables in such a way that a violation of the threshold values ​​is counteracted, a safety control that transfers the electrolysis system to a safe state, e.g. switches it off, if safety-relevant threshold values ​​are violated.

[0047] Fig. 2 shows an electrolysis system 200 for converting energy.

[0048] The electrolysis system 200 comprises a first cell stack 201 with a first cathode outlet path 203 and a first anode outlet path 205 and a second cell stack 207 with a second cathode outlet path 209 and a second anode outlet path 211.

[0049] The first cell stack 201 and the second cell stack 207 are hydraulically connected in parallel. A first cathode pressure sensor 213 is arranged on the first cathode outlet path 203 between the first cell stack 201 and a first check valve 215.

[0050] On the second cathode outlet path 209, a second cathode pressure sensor 217 is arranged between the second cell stack 207 and a second check valve 219.

[0051] An anode pressure sensor 223 is arranged in the flow direction after a first connection point 221, at which the first anode outlet path 205 and the second anode outlet path 211 are brought together.

[0052] A pressure deviation in the first cell stack 201 or the second cell stack 207 can be detected based on a deviation of a differential pressure between a cathode subsystem and an anode subsystem, such as a deviation of pressures determined by the first cathode pressure sensor 213 or the second cathode pressure sensor 217 in the first cathode outlet path 203 or the second cathode outlet path 209 in relation to values ​​measured by the anode pressure sensor 223.

[0053] The processing of the measured values ​​can in particular comprise the calculation of a differential pressure between the anode pressure and the stack-specific cathode pressures by a computing unit 229 in order, for example, to initiate safety functions when defined limit values ​​are exceeded or undershot.

[0054] In Fig. 3, the electrolysis system 200 is shown in another possible configuration.

[0055] Here, instead of the anode pressure sensor 223, the electrolysis system 200 comprises a differential pressure sensor 225, which measures a differential pressure between the anode pressure after the first connection point 221 and a cathode pressure after a second connection point 227. The differential pressure sensor 225 enables a mathematical determination of a stack-specific anode pressure by relating the measured values ​​determined by the differential pressure sensor 225 to a respective stack-specific cathode pressure.

Claims

Claims 1 . Diagnostic method (100) for diagnosing a condition of an electrolysis system (200) comprising a plurality of cell stacks (201, 207), the diagnostic method (100) comprising: Determining (101) a plurality of pressure differences between a respective stack-specific cathode pressure in a cathode outlet path (203, 209) of a cathode subsystem of each cell stack (201, 207) of the plurality of cell stacks (201, 207) and an anode pressure in an anode outlet path (205, 211) in the flow direction after a first connection point (221) at which all anode outlet paths (205, 211) of respective anode subsystems of the number of cell stacks (201, 207) are brought together, Outputting (103) a cell stack-specific reaction request in the event that a pressure difference between a respective stack-specific cathode pressure and the anode pressure deviates from a predetermined diagnostic threshold value, wherein the reaction request comprises information about which cell stack (201, 207) of the plurality of cell stacks (201, 207) the pressure difference deviates from the diagnostic threshold value.

2. Diagnostic method (100) according to claim 1, characterized in that determining (101) the pressure difference comprises: Measuring a number of cathode pressures by means of respective cathode pressure sensors (213, 217) arranged in a cathode outlet path (203, 209) of a cathode subsystem of each cell stack (201, 207) of the plurality of cell stacks (201, 207), Measuring an anode pressure by means of an anode pressure sensor (223) arranged in an anode outlet path (205, 211) in the flow direction after the first connection point (221) at which all anode outlet paths (205, 211) of respective anode subsystems of the plurality of cell stacks (201, 207) are brought together.

3. Diagnostic method (100) according to claim 1, characterized in that determining (101) the pressure difference comprises: Measuring the anode pressure by means of a differential pressure sensor (225) configured to determine a differential pressure between a respective cathode pressure in the flow direction after a second connection point (227), at which all cathode outlet paths (203, 209) of respective cathode subsystems of the plurality of cell stacks (201, 207) are brought together, and the anode pressure in the anode outlet path (205, 211) in the flow direction after the first connection point (221).

4. Diagnostic method (100) according to one of the preceding claims, characterized in that when measuring a respective cathode pressure, at least the corresponding cathode outlet path (203, 209) is fluidically decoupled from a downstream pressure source.

5. Diagnostic method (100) according to one of the preceding claims, characterized in that when measuring the anode pressure, all anode outlet paths (205, 211) are fluidically decoupled from a downstream pressure source.

6. Electrolysis system (200) for converting energy, wherein the electrolysis system (200) comprises: a plurality of cell stacks (201, 207), a computing unit (229), wherein the computing unit (229) is configured to carry out a diagnostic method (100) according to one of claims 1 to 5.

7. Electrolysis system (200) according to claim 6, characterized in that the electrolysis system (200) further comprises: a plurality of cathode pressure sensors (213, 217), wherein respective cathode pressure sensors (213, 217) of the plurality of cathode pressure sensors (213, 217) are configured to measure a stack-specific cathode pressure in a cathode outlet path (203, 209) of a cathode subsystem of a respective cell stack (201, 207) of the plurality of cell stacks (201, 207), an anode pressure sensor (223), wherein the anode pressure sensor (223, 225) is configured to measure an anode pressure in an anode outlet path in the flow direction after a connection point (221) at which all anode outlet paths (205, 211) of respective anode subsystems of the A plurality of cell stacks (201, 207) are brought together.

8. Electrolysis system (200) according to claim 6 or 7, characterized in that the electrolysis system (200) further comprises: a differential pressure sensor (225), wherein the differential pressure sensor (225) is configured to determine a differential pressure between a respective cathode pressure in the flow direction after a second connection point (227), at which all cathode outlet paths (203, 209) of respective cathode subsystems of the plurality of cell stacks are brought together, and the anode pressure in the anode outlet path (205, 211) in the flow direction after the first connection point (221).

9. A program product, wherein the program product comprises program code means which, when the program product is executed on a computing unit, configure the computing unit to execute a diagnostic method (100) according to one of claims 1 to 5.

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