Method and system for diagnosing the condition of a cell, a cell stack, or an electrolysis system

Abstract

The presented invention relates to a method (100) for diagnosing the condition of a cell (201) of a cell stack (203) of an electrolysis system (205), wherein the method (100) comprises: - Introducing (101) an inert gas into an anode tract of the cell stack (203), - Introducing (103) a hydrogen-containing gas into a cathode tract of the cell stack (203), - Measuring (105) a voltage applied to at least one cell (201) of the cell stack (203) while the anode tract is filled with the inert gas and the cathode tract is filled with the hydrogen-containing gas, and - Output (107) an error message in the event that the voltage measured at a given cell (201) is less than a specified diagnostic threshold.

Description

[0001] The presented invention relates to a method for diagnosing the condition of a cell of a cell stack of an electrolysis system and a diagnostic system for diagnosing the condition of a cell of a cell stack of an electrolysis system according to the attached claims. State of the art

[0002] Anion exchange membrane electrolyzers (AEMELs) comprise cell stacks with multiple cells. These cells can exhibit mechanical defects such as so-called "pinhole formations," which allow gases to pass through the membrane, thereby minimizing the performance and lifespan of a cell stack.

[0003] Pressure loss measurements are used to detect such a passage of gases through the membrane, but these measurements can only determine the overall state of a cell stack, not the state of individual cells. Disclosure of the invention

[0004] Within the scope of the presented invention, a method and a diagnostic system for diagnosing the condition of a cell in a cell stack of an electrolysis system are introduced. Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the diagnostic system according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention is always, or can always be, mutually referenced.

[0005] The presented invention serves in particular to provide a means of diagnosing the condition of a cell in a cell stack of an electrolysis system.

[0006] Thus, according to a first aspect of the presented invention, a method for diagnosing the condition of a cell of a cell stack of an electrolysis system is presented.

[0007] The presented method comprises introducing an inert gas into an anode tract of the cell stack, introducing a hydrogen-containing gas into a cathode tract of the cell stack, measuring a voltage applied to at least one cell of the cell stack while the anode tract is filled with the inert gas and the cathode tract with the hydrogen-containing gas, and issuing an error message if the voltage measured at a particular cell is less than a predetermined diagnostic threshold.

[0008] The presented method is based on introducing two different gases: an inert gas, such as nitrogen, into the anode tract and a hydrogen-containing gas into the cathode tract of a cell stack. The hydrogen-containing gas generates an electrical potential across the membrane of each cell. This potential decreases when hydrogen-containing gas diffuses from the cathode tract into the anode tract, indicating a cell defect.

[0009] Accordingly, by comparing a voltage measured at a particular cell with a diagnostic threshold, a critical or faulty condition of the cell, in which, for example, it exhibits an increased voltage change compared to other cells, can be detected and, for example, output on an output unit and / or in an error memory.

[0010] To measure the voltage applied to a cell, for example a voltage measuring device, in particular a multimeter or a multiplexer, can be electrically coupled to the respective bipolar plates or monopole plates of the cell.

[0011] The presented method can be carried out, in particular, before the commissioning of a cell stack, especially before initial commissioning during the manufacturing process of the cell stack. For example, voltages measured on individual cells can be archived in an acceptance protocol to document the quality of a cell stack.

[0012] The presented procedure can be performed with a dry or a wet cathode tract.

[0013] It may be provided that the inert gas includes nitrogen.

[0014] In particular, the inert gas can be pure nitrogen, which does not react with the hydrogen-containing gas and is therefore harmless.

[0015] It can still be stipulated that the hydrogen-containing gas is pure hydrogen.

[0016] Alternatively, it can be provided that the hydrogen-containing gas comprises a mixture of hydrogen and nitrogen.

[0017] It may be provided that the hydrogen-containing gas is partially or completely saturated with gaseous water.

[0018] For example, it may be stipulated that the mixture contains between 3% and 99% hydrogen, in particular 5%.

[0019] It may be provided that the inert gas in the anode tract is partially or completely saturated with gaseous water.

[0020] It may also be provided that the anode tract is rinsed with an alkaline electrolyte solution before the inert gas is introduced into the anode tract.

[0021] Rinsing the anode tract with an alkaline electrolyte solution removes any contaminants that may have accumulated in the anode tract and protects the cell from damage caused by so-called poisoning.

[0022] It may be provided that the alkaline electrolyte solution includes potassium hydroxide.

[0023] In experiments, a potassium hydroxide solution with a molarity between 0.5 molar and 6 molar has proven to be particularly suitable for rinsing the anode tract.

[0024] It may also be provided that the hydrogen-containing gas is introduced into the cathode tract at a pressure between 2 bar and 40 bar.

[0025] A high pressure of hydrogen-containing gas in the cathode tract tests the membrane of each cell with a high load, so that a particularly valid statement can be made about the condition of the cell.

[0026] It may also be provided that the diagnostic threshold is formed based on all voltages measured on the respective cells.

[0027] A relative diagnostic threshold, calculated based on all voltages measured at each cell (e.g., as the average of the voltages), minimizes the effect of measurement conditions and reliably identifies potentially defective cells. This also minimizes the probability of a false positive error message.

[0028] It may also be provided that the procedure is carried out before the cell stack is put into operation and that, in the event that a voltage measured on a particular cell is less than the diagnostic threshold, the cell is replaced.

[0029] It can also be designed so that, in the event of a pinhole, the hydrogen content is fed to the anode tract, thus making a transient change in the voltages of all cells detectable. A faster change in voltage identifies the defective cell.

[0030] By replacing a cell before commissioning the cell stack, e.g. during a manufacturing process for producing an electrolysis system, the need for a complex opening of the cell stack after commissioning can be avoided.

[0031] According to a second aspect, the presented invention relates to a diagnostic system for diagnosing the condition of a cell in a cell stack electrolysis system.

[0032] Advantages that are described in detail in relation to the method for diagnosing the condition of a cell of a cell stack of an electrolysis system according to the first aspect of the invention apply equally to the diagnostic system for diagnosing the condition of a cell of a cell stack of an electrolysis system according to the second aspect of the invention, and vice versa.

[0033] The presented diagnostic system comprises a first gas source for inert gas, a second gas source for hydrogen-containing gas, a voltage measuring device and a computing unit, the computing unit being configured to carry out one possible embodiment of the presented method.

[0034] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

[0035] They each show schematically: Fig. 1. a possible design of the presented procedure and Fig. 2. A possible design of the presented diagnostic system.

[0036] In Fig. Figure 1 shows a method 100 for diagnosing the condition of a cell of a cell stack of an electrolysis system.

[0037] The procedure comprises a first induction step 101, in which an inert gas is introduced into an anode tract of the cell stack, a second induction step 103, in which a hydrogen-containing gas is introduced into a cathode tract of the cell stack, a measurement step 105, in which a voltage applied to at least one cell of the cell stack is measured while the anode tract is filled with the inert gas and the cathode tract with the hydrogen-containing gas, and an output step 107, in which an error message is issued if the voltage measured at a particular cell is less than a predetermined diagnostic threshold.

[0038] In Fig. Figure 2 shows a diagnostic system 200 for diagnosing the condition of a cell 201, a cell stack 203, or an electrolysis system 205.

[0039] The diagnostic system 200 comprises a first gas source 207 for inert gas, a second gas source 209 for hydrogen-containing gas, a voltage measuring device 211 and a computing unit 213.

[0040] The computing unit 213 is configured to execute procedure 100 according to Fig. 1.

Claims

[1] Method (100) for diagnosing the condition of a cell (201) of a cell stack (203) of an electrolysis system (205), wherein the method (100) comprises: - Introducing (101) an inert gas into an anode tract of the cell stack (203), - Introducing (103) a hydrogen-containing gas into a cathode tract of the cell stack (203), - Measuring (105) a voltage applied to at least one cell (201) of the cell stack (203) while the anode tract is filled with the inert gas and the cathode tract is filled with the hydrogen-containing gas, and - Output (107) an error message in the event that the voltage measured at a given cell (201) is less than a specified diagnostic threshold. [2] Method (100) according to claim 1, characterized by that the inert gas includes nitrogen. [3] Method (100) according to claim 1 or 2, characterized by that the hydrogen-containing gas is pure hydrogen. [4] Method (100) according to claim 1 or 2, characterized by that the hydrogen-containing gas comprises a mixture of hydrogen and nitrogen. [5] Method (100) according to any one of the preceding claims, characterized by , that before introducing the inert gas into the anode tract, the anode tract is rinsed with an alkaline electrolyte solution. [6] Method (100) according to claim 1 or 2, characterized by that the hydrogen-containing gas is a mixture of hydrogen and nitrogen or pure hydrogen, partially or completely saturated with water. [7] Method (100) according to claim 1 or 2, characterized by that before the inert gas is introduced into the anode tract, the anode tract is partially or completely saturated with water. [8] Method (100) according to claim 1 or 2, wherein the error message is issued in the event that a transient voltage change is detected. [9] Method (100) according to claim 5, characterized bythat the alkaline electrolyte solution contains potassium hydroxide. [10] Method (100) according to any one of the preceding claims, characterized by , that the inert gas is introduced into the anode tract at a pressure between 2 bar and 6 bar. [11] Method (100) according to any of the preceding claims, characterized by , that the hydrogen-containing gas is introduced into the cathode tract at a pressure between 2 bar and 40 bar. [12] Method (100) according to any one of the preceding claims, characterized by , that the diagnostic threshold is formed based on all voltages measured on respective cells (201). [13] Method (100) according to any of the preceding claims, characterized by , that the respective voltages on a large number of cells (201) are measured using a multiplexer. [14] Method (100) according to any of the preceding claims, characterized by, that the procedure (100) is carried out before the cell stack (203) is put into operation and in the event that a voltage measured on a particular cell (201) is less than the diagnostic threshold, the cell (201) is replaced. [15] Diagnostic system (200) for diagnosing the condition of a cell (201) of a cell stack (203) of an electrolysis system (205), wherein the diagnostic system (200) comprises: - a first gas source (207) for inert gas, - a second gas source (209) for hydrogen-containing gas, - a voltage measuring device (211) and - a computing unit (213) wherein the computing unit (213) is configured to perform a method (100) according to any one of claims 1 to 14.

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