Water electrolysis cell abnormality detection device

Abstract

The purpose is to detect cell abnormalities caused by contamination. [Solution] An abnormality detection device for a water electrolysis cell, comprising a calculation device, the calculation device performs a calculation to determine a cell abnormality by measuring IV at low temperature and differentiating the obtained IV measurement value to verify the presence or absence of an inflection point in the medium load region.

Description

Technical Field

[0001] The present disclosure relates to an abnormal detection device for a water electrolysis cell.

Background Art

[0002] Patent Document 1 discloses determining an abnormality from the voltage drop time when water electrolysis stops. Patent Document 2 discloses determining an abnormality from the voltage values of a plurality of cells. Further, Patent Document 3 discloses supplying hydrogen at startup or shutdown and determining an abnormality from the open-circuit voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, it is possible to detect a micro short circuit, but it is impossible to detect deterioration due to ion contamination. Therefore, an object of the present disclosure is to determine cell abnormality due to contamination.

Means for Solving the Problems

[0005] The present application discloses an abnormal detection device for a water electrolysis cell, which has an arithmetic unit. The arithmetic unit performs an operation for determining cell abnormality by performing I-V measurement at a low temperature and verifying the presence or absence of an inflection point in the medium load region by differentiating the obtained I-V measurement values.

[0006] IV measurements at low temperatures may be performed when the water electrolysis process is started.

[0007] Low temperature can also refer to a temperature range of 25°C to 35°C. [Effects of the Invention]

[0008] According to this disclosure, cell abnormalities due to contamination can be accurately determined from the amount of change in a portion of the cell. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a conceptual diagram illustrating the configuration of the water electrolysis device 10. [Figure 2] Figure 2 is a conceptual diagram of the computer 50 (control device 50). [Figure 3] Figure 3 shows the flow of the abnormality detection control S10. [Figure 4] Figure 4 shows an example of an IV curve. [Figure 5] Figure 5 shows an example of the derivative result of the IV curve. [Modes for carrying out the invention]

[0010] 1.Water electrolysis device Figure 1 conceptually represents a water electrolysis apparatus 10 in one configuration. In this embodiment, the water electrolysis device 10 includes a water electrolysis stack 20, an oxygen-side path 30, a hydrogen-side path 40, and a computing device 50 that constitutes an abnormality detection device. In the water electrolysis device 10, pure water is supplied to the water electrolysis cell 21 provided in the water electrolysis stack 20 from the oxygen-side path 30 and energized to decompose the water into hydrogen and oxygen, obtaining hydrogen which is then separated into the hydrogen-side path 40.

[0011] 1.1. Water electrolysis stack, water electrolysis cell, sensor A water electrolysis cell is a unit element for decomposing pure water into hydrogen and oxygen, and multiple such water splitting cells are stacked and arranged in a water electrolysis stack 20. The water electrolysis cell is as known. In this form, it consists of multiple layers, with one side being the oxygen generation electrode (anode) and the other side being the hydrogen generation electrode (cathode) sandwiching a solid polymer electrolyte membrane. The material constituting the solid polymer electrolyte membrane is a solid polymer material, and examples include proton-conductive ion exchange membranes formed from fluorine-based resins, hydrocarbon-based resin materials, etc. This exhibits good proton conductivity (electrical conductivity) in a wet state. More specifically, Nafion (registered trademark), which is a perfluorosulfonic acid membrane, can be mentioned.

[0012] The oxygen generation electrode (anode) includes an oxygen electrode catalyst layer, an oxygen electrode gas diffusion layer, and an oxygen electrode separator in this order from the solid polymer electrolyte membrane side. The oxygen electrode separator has a flow path through which pure water and decomposed oxygen supplied to the oxygen electrode gas diffusion layer flow.

[0013] The hydrogen generation electrode (cathode) is provided on the surface of the solid polymer electrolyte membrane opposite to the surface on which the oxygen generation electrode is disposed, and includes a hydrogen electrode catalyst layer, a hydrogen electrode gas diffusion layer, and a hydrogen electrode separator in this order from the solid polymer electrolyte membrane side. The hydrogen electrode separator has a flow path through which separated hydrogen and water accompanying it flow.

[0014] The pure water (H2O) supplied from the flow path of the oxygen electrode separator to the oxygen generation electrode is decomposed into oxygen, electrons, and protons (H + ) in the oxygen electrode catalyst layer with an applied potential by applying current between the oxygen generation electrode and the hydrogen generation electrode by a power source. At this time, the protons move through the solid polymer electrolyte membrane to the hydrogen electrode catalyst layer. On the other hand, the electrons separated in the oxygen electrode catalyst layer reach the hydrogen electrode catalyst layer through the external circuit. Then, at the hydrogen electrode catalyst layer, the protons receive the electrons and hydrogen is generated. The generated hydrogen reaches the hydrogen electrode separator and is discharged from the flow path, and moves to the hydrogen-side path 40. Note that the oxygen separated in the oxygen electrode catalyst layer reaches the oxygen electrode separator and is discharged from the flow path, and moves to the oxygen-side path 30.

[0015] Further, in the water electrolysis stack 20, it is configured to obtain the relationship between the current density I and the voltage V for each of the plurality of arranged water electrolysis cells 21. The specific form is not particularly limited as long as the voltage and current of each of the plurality of water electrolysis cells 21 can be measured. For example, a sensor (voltage sensor) 29 can be arranged for each water electrolysis cell 21 as in this embodiment. As will be described later, the arithmetic unit 50 performs a process of determining the presence or absence of an abnormality based on the voltage value obtained in each water electrolysis cell 21 and the like.

[0016] 1.2. Oxygen-side path (water supply-side path) The oxygen-side path (water supply-side path) 30 is a path including a pipe that supplies pure water to the water electrolysis cell 21 of the water electrolysis stack 20 to obtain oxygen. In the oxygen-side path 30, pure water is supplied toward the water electrolysis stack 20 by the pump 31, and the generated oxygen and the unused water are discharged from the water electrolysis stack 20 and supplied to the gas-liquid separator 32. In the gas-liquid separator 32, pure water and oxygen are separated. The separated oxygen is discharged, and the pure water is supplied to the pump 31 again. In addition, the insufficient pure water is supplied from the pump 33 to the gas-liquid separator 32. These devices are connected by pipes.

[0017] 1.3. Hydrogen-side path The hydrogen-side path 40 is a path including a pipe that extracts the hydrogen separated in the water electrolysis stack 20. In the hydrogen-side path 40, the hydrogen and water (pure water) discharged from the water electrolysis cell 21 of the water electrolysis stack 20 are supplied to the gas-liquid separator 41. In the gas-liquid separator 41, water and hydrogen are separated. The separated hydrogen is collected, and the water is sent by the pump 42 to the gas-liquid separator 32 of the oxygen-side path 30 and reused. These devices are connected by pipes.

[0018] 1.4. Arithmetic unit The arithmetic unit 50 constituting the abnormality detection device is a controller that detects an abnormality in the water electrolysis device as will be described later. The mode of the arithmetic unit 50 is not particularly limited, but typically it can be configured by a computer. FIG. 2 conceptually shows a configuration example of the computer 50 as the arithmetic unit 50.

[0019] The computer 50 includes a CPU (Central Processing Unit) 51 which is a processor, RAM (Random Access Memory) 52 which functions as a work area, ROM (Read-Only Memory) 53 as a storage medium, a receiving unit 54 which is an interface for receiving information into the computer 50 whether wired or wireless, and an output unit 55 which is an interface for sending information from the computer 50 to the outside whether wired or wireless. The receiving unit 54 is electrically connected to sensors 29 and other components provided on the water electrolysis stack 20, and is configured to receive voltage and current as signals. On the other hand, a monitor or the like is connected to the output unit 55 to display the result of the determination of whether or not there is an abnormality.

[0020] Computer 50 stores a computer program that uses the process of detecting and controlling abnormalities in the water electrolysis device as specific commands and executes them. In computer 50, the CPU 51, RAM 52, and ROM 53, which are hardware resources, work together with the computer program. Specifically, the CPU 51 performs its function by executing the computer program recorded in ROM 53 in RAM 52, which functions as a work area, based on signals representing voltage and current acquired via the receiving unit 54. Information acquired or generated by the CPU 51 is stored in RAM 52. In addition, based on the process of detecting and controlling abnormalities in the water electrolysis device, the presence or absence of abnormalities is displayed on the monitor via the output unit 55 as needed. The specific details of the abnormality detection and control system for water electrolysis equipment will be explained next.

[0021] 2. Abnormality detection and control of water electrolysis equipment Figure 3 shows the flow of the abnormality detection control S10 for one configuration of a water electrolysis apparatus. As can be seen from Figure 3, the abnormality detection control S10 includes processes S11 to S17. The computer program stored in the aforementioned arithmetic unit 50 consists of specific instructions to the computer for executing each process of the abnormality detection control S10.

[0022] 2.1. Process S11 In process S11, the water electrolysis device is started.

[0023] 2.2. Process S12 In process S12, the detection sequence (detection) is initiated. Detection is performed in a temperature range lower than the normal operating temperature before the water electrolysis device reaches its normal operating temperature. Anomalies can be detected by verifying the presence or absence of inflection points in the medium-load region of this lower temperature range, as described later. There is no particular limit to the preferred temperature range, but it is preferable that the water temperature at the outlet side of the water electrolysis stack be 25°C to 35°C.

[0024] 2.3. Process S13 In process S13, the current density I (A / cm²) 2 An IV curve, which represents the relationship between current and voltage (V), is obtained. Specifically, a load is applied from low current to high current, and the voltage is measured for each to obtain the IV curve. An example of an IV curve is shown in Figure 4. In Figure 4, the horizontal axis is current density and the vertical axis is voltage. In this embodiment, the relationship between current and measured voltage was used, but instead of the measured voltage, the voltage difference with a pre-stored reference voltage or, if multiple cells or stacks are arranged in a row, the voltage difference between them may be used.

[0025] In process S13, the obtained IV curve is further differentiated. Figure 5 shows an example of a graph with the differentiation result on the vertical axis and current density on the horizontal axis. Figure 5 shows examples of steady-state operation and low-temperature operation (detection control).

[0026] 2.4. Process S14~Process S17 In process S14, it is determined whether there is an upward-convex inflection point in the derivative result of the IV curve obtained in process S13 (for example, Figure 5). For example, according to the example in Figure 5, the current density is 1.25 (A / cm²). 2 There is an inflection point that is convex upwards near the ) mark. The inventors have found that in the case of cell abnormalities due to contamination, an inflection point that is convex upwards occurs. This is especially true in the low-temperature region and the medium-load region (current density 0.5 A / cm²).2 (The above) results in at least one such inflection point.

[0027] As shown in the example in Figure 5, when at least one inflection point occurs, the response is "Yes" in process S14, and this is communicated in process S15 (display on the screen, warning light, warning sound, etc.), the detection sequence is terminated in process S16, and the system returns to normal operation in process S17. On the other hand, if the inflection point does not occur, the result is "No" in process S14, the detection sequence is terminated in process S16, and the system transitions to normal operation in process S17.

[0028] 3. Effects, etc. According to the water electrolysis cell abnormality detection device disclosed herein, cell abnormalities due to ion contamination can be accurately determined from the amount of change in different parts. This allows for, for example, detection of whether or not the ion exchange resin needs to be replaced, maximizing the lifespan of the stack, or knowing when the stack needs to be replaced before it fails, thereby minimizing the downtime of the entire system. [Explanation of Symbols]

[0029] 10...Water electrolysis device, 20...Water electrolysis stack, 21...Water electrolysis cell, 29...Sensor (voltage sensor), 30...Oxygen side path (water supply side path), 40...Hydrogen side path, 50...Computation unit (anomaly detection device)

Claims

1. An abnormality detection device for a water electrolysis cell, It has a computing device, The aforementioned computing device performs a calculation to determine cell abnormalities by measuring I-V at low temperatures and differentiating the obtained I-V measurement value to verify the presence or absence of inflection points in the medium-load region. An abnormality detection device for water electrolysis cells.

2. The abnormality detection device for a water electrolysis cell according to claim 1, wherein the I-V measurement at low temperature is performed when water electrolysis is started.

3. The abnormality detection device for a water electrolysis cell according to claim 1 or 2, wherein the low temperature range is 25°C to 35°C.

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