Short-circuit detection method for water electrolysis device, hydrogen production method and water electrolysis device

Abstract

This invention relates to a short-circuit detection method for a water electrolysis apparatus, a hydrogen production method, and a water electrolysis apparatus, enabling short-circuit detection even during operation. Voltage sensors are installed in multiple water electrolysis chambers. During operation of the water electrolysis apparatus, the voltage in each chamber is measured using these sensors. If the detected voltage is below a reference voltage, a short circuit is determined.

Description

Technical Field

[0001] This disclosure relates to short-circuit detection of a water splitting device. Background Technology

[0002] Patent Document 1 discloses a procedure for detecting short circuits in a stopped reactor. Specifically, the chamber resistance R is calculated based on the current value I when an external voltage V is applied using an auxiliary power supply, and the resistance is determined by whether R is within a threshold value.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-196906

[0004] However, with this existing technology, the water electrolysis unit cannot detect short circuits during operation. That is, voltage is applied to the reactor while it is in a stopped state via an auxiliary power supply, thus allowing only anomaly detection during shutdown. Summary of the Invention

[0005] Therefore, the purpose of this disclosure is to enable short circuit detection even during operation in a water electrolysis device.

[0006] This application discloses a short-circuit detection method for a water electrolysis device, which detects short circuits in the water electrolysis chambers of a water electrolysis device equipped with multiple water electrolysis chambers. A voltage sensor is installed in each of the multiple water electrolysis chambers. During the operation of the water electrolysis device, the voltage of the water electrolysis chamber is measured by the voltage sensor. If the voltage is less than the reference voltage, it is determined to be a short circuit.

[0007] It can also be configured such that, in order to detect short circuits, the current density is reduced compared to the current density during steady-state water electrolysis to determine if a short circuit has occurred.

[0008] Furthermore, this application discloses a short-circuit detection method for a water electrolysis device, which is a method for detecting short circuits in the water electrolysis chambers of a water electrolysis device equipped with multiple water electrolysis chambers. A voltage sensor is installed for every n water electrolysis chambers. During the operation of the water electrolysis device, the voltage of the n water electrolysis chambers is measured by the voltage sensor. The steady-state water electrolysis voltage is set to V. m And set the reference voltage to V b When the detected voltage becomes less than (n-1)V m +V b When this occurs, it is determined to be a short circuit.

[0009] In addition, this application discloses a hydrogen production method, which generates hydrogen through a water electrolysis device and performs short-circuit detection using a short-circuit detection method for the aforementioned water electrolysis device.

[0010] In addition, this application discloses a water electrolysis device, which obtains hydrogen by electrolyzing water through water electrolysis chambers. The water electrolysis device includes: multiple water electrolysis chambers; voltage sensors respectively disposed in the multiple water electrolysis chambers; and a controller that obtains voltage from the voltage sensors. If the voltage obtained during the process of generating hydrogen from the water electrolysis chambers is less than the reference voltage, the controller reports a short circuit.

[0011] Alternatively, it can be configured such that, in order to perform short-circuit detection, the controller periodically reduces the current density to a level lower than the steady-state water electrolysis voltage to obtain the voltage.

[0012] Furthermore, this application discloses a water electrolysis device that obtains hydrogen through water electrolysis in a water electrolysis chamber. The device comprises: a plurality of water electrolysis chambers; voltage sensors arranged for every n water electrolysis chambers; and a controller that obtains voltage from the voltage sensors. During operation, the controller measures the voltage of each of the n water electrolysis chambers using the voltage sensors and sets the steady-state water electrolysis voltage to V. m And set the reference voltage to V b At that time, the voltage measured in n water electrolysis chambers becomes less than (n-1)V. m +V b In such cases, a short circuit should be reported.

[0013] According to this disclosure, short circuits can be detected continuously during the operation of the water electrolysis device, and short circuits can be detected as early as possible. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the structure of the water electrolysis device 10.

[0015] Figure 2 This is a schematic diagram illustrating the structure of the water electrolysis chamber 21.

[0016] Figure 3 This is a schematic diagram of computer 50 (controller 50).

[0017] Figure 4 This is a flowchart illustrating the short-circuit detection method S10 of a water electrolysis device.

[0018] Figure 5 This is a diagram illustrating the short-circuit detection method S10 for a water electrolysis device.

[0019] Figure 6 This is a flowchart illustrating the short-circuit detection method S20 of a water electrolysis device.

[0020] Figure 7 This is a diagram illustrating the short-circuit detection method S20 for a water electrolysis device.

[0021] Explanation of reference numerals in the attached figures

[0022] 10…Water electrolysis unit; 20…Water electrolysis stack; 21…Water electrolysis chamber; 29…Sensor (voltage sensor); 30…Oxygen-side path (water supply-side path); 40…Hydrogen-side path; 50…Controller. Detailed Implementation

[0023] 1. Water electrolysis device

[0024] exist Figure 1 The diagram schematically illustrates a water electrolysis apparatus 10 involved in one of the methods.

[0025] 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 controller 50. In the water electrolysis device 10, pure water is supplied to the water electrolysis chamber 21 of the water electrolysis stack 20 from the oxygen-side path 30 and electricity is applied to decompose water into hydrogen and oxygen, thereby obtaining hydrogen and separating it to the hydrogen-side path 40.

[0026] 1.1. Water electrolysis reactor, water electrolysis chamber, sensors

[0027] exist Figure 2 The diagram schematically illustrates the configuration of the water electrolysis chamber 21. The water electrolysis chamber 21 is a unit element for decomposing pure water into hydrogen and oxygen, and multiple such water electrolysis chambers 21 are stacked together to form a water electrolysis stack 20.

[0028] The water electrolysis chamber 21 is as is known, but in this embodiment it is composed of multiple layers, with a solid polymer electrolyte membrane 22 sandwiched between one side as the oxygen generating electrode (anode) and the other side as the hydrogen generating electrode (cathode).

[0029] The material constituting the solid polymer electrolyte membrane 22 is a solid polymer material, such as a proton-conducting ion exchange membrane formed by fluorinated resins, hydrocarbon resins, etc.

[0030] It exhibits good proton conductivity (electrical conductivity) in a wet state. More specifically, Nafion (registered trademark) can be cited as an example of a perfluorosulfonic acid membrane.

[0031] At the oxygen generating electrode (anode), an oxygen electrode catalyst layer 23, an oxygen electrode gas diffusion layer 24, and an oxygen electrode separator 25 are sequentially provided from the side of the solid polymer electrolyte membrane 22.

[0032] The oxygen electrode catalyst layer 23 is a layer composed of electrode catalysts including at least one noble metal catalyst such as Pt, Ru, Ir and its oxide.

[0033] The oxygen polar gas diffusion layer 24 is composed of components that are breathable and conductive.

[0034] Specifically, examples include porous conductive components made of metal fibers or metal particles.

[0035] The oxygen electrode isolator 25 is a component having a flow path 25a for supplying pure water and decomposed oxygen to the oxygen electrode gas diffusion layer 24.

[0036] The hydrogen generating electrode (cathode) is disposed on the side of the solid polymer electrolyte membrane 22 opposite to the side where the oxygen generating electrode is disposed. From the solid polymer electrolyte membrane 22 side, a hydrogen electrode catalyst layer 26, a hydrogen electrode gas diffusion layer 27, and a hydrogen electrode separator 28 are sequentially provided.

[0037] Examples of hydrogen electrode catalyst layers 26 include layers containing Pt, for instance.

[0038] The hydrogen polar gas diffusion layer 27 is composed of components that are breathable and conductive. Specifically, porous components such as carbon cloth and carbon paper can be used as examples.

[0039] The hydrogen electrode isolator 28 is a component having a flow path 28a for the separation of hydrogen and the flow of water accompanying the hydrogen.

[0040] By applying an electric current between the oxygen generating electrode and the hydrogen generating electrode, pure water (H2O) supplied from the oxygen electrode isolator 25a to the oxygen generating electrode is decomposed into oxygen, electrons, and protons (H2O) in the oxygen electrode catalyst layer 23 under applied potential. + At this point, protons pass through the solid polymer electrolyte membrane 22 and move toward the hydrogen electrode catalyst layer 26. Meanwhile, electrons separated in the oxygen electrode catalyst layer 23 pass through an external circuit and reach the hydrogen electrode catalyst layer 26. Furthermore, in the hydrogen electrode catalyst layer 26, protons accept electrons to produce hydrogen. The produced hydrogen reaches the hydrogen electrode isolator 28 and is discharged from the flow path 28a, moving toward the hydrogen-side path 40. Additionally, oxygen separated in the oxygen electrode catalyst layer 23 reaches the oxygen electrode isolator 25 and is discharged from the flow path 25a, moving toward the oxygen-side path 30.

[0041] Furthermore, the water electrolysis reactor 20 is configured to measure the voltage of each of the multiple water electrolysis chambers 21. The specific method is not particularly limited as long as the voltage of each of the multiple water electrolysis chambers 21 can be measured, but for example, a sensor (voltage sensor) 29 can be configured for each water electrolysis chamber 21 as in this embodiment. As will be described later, based on the voltage values ​​obtained in each water electrolysis chamber 21, the controller 50 performs a process to determine whether a short circuit exists.

[0042] Furthermore, in water electrolysis (hydrogen generation), if each water electrolysis chamber 21 is functioning normally (not short-circuited), then the steady-state current density J... m (A / cm 2 steady-state voltage Vm (V) come to work.

[0043] On the other hand, if a short circuit occurs, even with the same current density, the voltage will be lower than the steady-state voltage.

[0044] 1.2. Oxygen-side path (water supply-side path)

[0045] The oxygen-side path (water-side path) 30 is the path, including piping, that supplies pure water to the water electrolysis chamber 21 of the water electrolysis reactor 20 to obtain oxygen. In the oxygen-side path 30, pure water is supplied to the water electrolysis reactor 20 via pump 31. The generated oxygen and unused water are discharged from the water electrolysis reactor 20 and supplied to the gas-liquid separator 32. In the gas-liquid separator 32, the pure water and oxygen are separated. The separated oxygen is discharged, and the pure water is supplied back to pump 31. Additionally, any remaining pure water is supplied to the gas-liquid separator 32 via pump 33. These devices are connected via piping.

[0046] 1.3. Hydrogen-side pathway

[0047] The hydrogen-side path 40 includes piping for extracting hydrogen separated in the water electrolyzer 20. In the hydrogen-side path 40, hydrogen and water (pure water) discharged from the water electrolysis chamber 21 of the water electrolyzer 20 are supplied to the gas-liquid separator 41. The water and hydrogen are separated in the gas-liquid separator 41.

[0048] The separated hydrogen is collected and pumped via pump 42 to the gas-liquid separator 32 in the oxygen-side path 30 for reuse. These devices are connected by piping.

[0049] 1.4. Controller

[0050] The controller 50 is used to implement the short-circuit detection method of the water electrolysis apparatus of this disclosure via the water electrolysis apparatus 10. The form of the controller 50 is not particularly limited, but it can typically be configured as a computer. Figure 3 The diagram schematically illustrates an example of the structure of a computer 50, which serves as a controller 50.

[0051] The computer 50 includes a CPU (Central Processing Unit) 51, which functions as a processor; RAM (Random Access Memory) 52, which functions as a working area; ROM (Read-Only Memory) 53, which serves as a storage medium; a receiving unit 54, which serves as an interface for receiving information from the computer 50 via wired or wireless means; and an output unit 55, which serves as an interface for transmitting information from the computer 50 to the outside via wired or wireless means.

[0052] The configuration is such that each sensor 29 installed in the water electrolysis reactor 20 is electrically connected to the receiving unit 54, and is able to receive the value (voltage) of each sensor as a signal.

[0053] On the other hand, a monitor is connected to the output unit 55 to display the determination result of whether a short circuit exists.

[0054] The computer 50 stores a computer program for making the process of the short-circuit detection method of the water electrolysis apparatus of this disclosure into specific instructions and executing those instructions. In the computer 50, the CPU 51, RAM 52, and ROM 53, as hardware resources, operate in conjunction with the computer program. Specifically, the CPU 51 performs its function by executing the computer program recorded in the ROM 53 in the RAM 52, which functions as a working area, based on a signal indicating pressure from the sensor 29 obtained via the receiving unit 54. Information obtained or generated by the CPU 51 is stored in the RAM 52. Furthermore, based on the process of the short-circuit detection method of the water electrolysis apparatus of this disclosure, the presence or absence of a short circuit is displayed on a monitor via the output unit 55 as needed.

[0055] The following describes the specific short-circuit detection method for the water electrolysis device disclosed in this invention.

[0056] 2. Short-circuit detection method for water electrolysis device (Type 1)

[0057] exist Figure 4 The flowchart of the short-circuit detection method S10 (hereinafter referred to as "detection method S10") of the water electrolysis apparatus according to the first aspect of this disclosure is shown. Figure 4 As can be seen, detection method S10 includes processes S11 to S15. The computer program stored in the controller 50 described above consists of specific computer-specific instructions for executing each process of detection method S10.

[0058] 2.1. Process S11

[0059] In process S11, while water decomposition is underway, the voltage of each water electrolysis chamber 21 is obtained from the sensor 29 of each water electrolysis chamber 21. At this time, as... Figure 5 As shown, the steady-state current density J in each water electrolysis chamber is... m (A / cm 2 ).

[0060] 2.2. Processes S12, S13, and S14

[0061] In process S12, for each of the multiple water electrolysis chambers 21, it is determined whether the voltage is insufficient for the reference voltage V. b .like Figure 5 As shown, at steady-state current density J m(A / cm 2 Under normal conditions (without a short circuit), the steady-state voltage V is... m (V), but if a short circuit occurs, the voltage becomes insufficient to reach the reference voltage V. b (Point A). Here, the reference voltage V b The specific size is not particularly limited, but it can be, for example, 1.48 (V).

[0062] When the voltage in process S12 is the reference voltage V b In the above cases, select "No" and proceed to process S13. In process S13, it is determined that there is no short circuit in the water electrolysis chamber 21.

[0063] On the other hand, when the voltage is insufficient to the reference voltage V during process S12 b If the condition is met, the selection is yes, and the process proceeds to S14. In process S14, it is determined that a short circuit exists in the water electrolysis chamber 21.

[0064] 2.3. Process S15

[0065] In process S15, the results determined in processes S13 and S14 are reported by displaying them on a monitor or the like. In this display, in addition to whether a short circuit exists, the position of the water electrolysis chamber 21 that is the object of the determination of its existence or absence (the stacking position of the multiple water electrolysis chambers 21, etc.) can also be displayed.

[0066] 2.4. Effects, etc.

[0067] In the detection method S10 of this approach, hydrogen production based on conventional water electrolysis can be performed, and short circuit detection can be conducted, thus always clearly indicating the presence or absence of a short circuit. Furthermore, the number of monitors required can be reduced, achieving miniaturization and lower cost.

[0068] Furthermore, as described above, the configuration is to obtain a voltage from one water electrolysis chamber. However, it is not limited to this; for example, two water electrolysis chambers can be combined to obtain a voltage, or three or more (n) water electrolysis chambers can be combined to obtain a voltage. In this case, for the determination in process S12, the voltage detected is less than the reference voltage V. b This criterion applies when the detected voltage is less than (n-1)·V. m +V b In this case, it can be determined that a short circuit exists in any one of the n water electrolysis chambers. However, since n is a relatively small number, it is easier to identify water electrolysis chambers that are prone to short circuits, and therefore it is preferred.

[0069] 3. Short-circuit detection method for water electrolysis device (Type 2)

[0070] exist Figure 6The flowchart of the short-circuit detection method S20 (hereinafter referred to as "detection method S20") of the water electrolysis apparatus according to the second aspect of this disclosure is shown. Figure 6 As can be seen, detection method S20 includes processes S21 to S26. The computer program stored in the controller 50 described above consists of specific computer-specific instructions for executing each process of detection method S20.

[0071] 3.1. Process S21

[0072] In process S21, under the condition of water decomposition, such as Figure 7 As shown, the current density is reduced from J m Descending to J l (decreasing current density J) l (A / cm 2 The detected voltage decreases due to the decrease in current density, but this decrease in current density does not cause the detected voltage to fall below the reference voltage V. b Decreasing current density J l The specific size is not particularly limited, but for example, it can be 0.1 (A / cm). 2 ).

[0073] 3.2. Process S22

[0074] In process S22, while water decomposition is underway, the voltage of each water electrolysis chamber 21 is obtained from the sensor 29 of each water electrolysis chamber 21. At this time, each water electrolysis chamber... Figure 7 The figure shows the decreasing current density J. l (A / cm 2 ).

[0075] 3.3. Processes S23, S24, and S25

[0076] In process S23, for each of the multiple water electrolysis chambers 21, it is determined whether the voltage is insufficient for the reference voltage V. b .like Figure 7 As shown, at a decreasing current density J l (A / cm 2 Under normal conditions (without a short circuit), the voltage drop is V. l (V), but if a short circuit occurs, the voltage becomes insufficient to reach the reference voltage V. b (Point B). Here, the reference voltage V b The specific size is not particularly limited, but it can be, for example, 1.48 (V).

[0077] When the voltage in process S23 is the reference voltage V bIn the above cases, select "No" and proceed to process S24. In process S24, it is determined that there is no short circuit in the water electrolysis chamber 21.

[0078] On the other hand, when the voltage is insufficient to the reference voltage V in process S23 b In the case of [condition], the selection is yes, and process S25 is initiated. In process S25, it is determined that a short circuit exists in the water electrolysis chamber 21.

[0079] 3.4. Process S26

[0080] In process S26, the results determined in processes S24 and S25 are reported by displaying them on a monitor or the like. In this display, in addition to whether a short circuit exists, the position of the water electrolysis chamber 21 that is the object of the determination of its existence or absence (such as the stacking position of the multiple water electrolysis chambers 21) can also be displayed.

[0081] 3.5. Effects, etc.

[0082] In the detection method S20 of this approach, although the efficiency is lower than that of conventional water electrolysis, it allows for short-circuit detection simultaneously with water electrolysis, thus ensuring a consistent awareness of the presence or absence of a short circuit. At this point, compared to... Figure 5 and Figure 7 It can be seen that the voltage detected by detection method S20 when there is no short circuit ( Figure 5 V m , Figure 7 V l ) and reference voltage V b The difference is small. Therefore, in detection method S20, compared to detection method S10, the voltage drops to the reference voltage V are minimal. b Therefore, the detection accuracy is improved, and short circuit detection can be performed as early as possible.

[0083] The detection method S20 can be used to periodically perform short-circuit detection in normal hydrogen production to produce hydrogen.

Claims

1. A short-circuit detection method for a water electrolysis device, comprising a method for detecting short circuits in the water electrolysis chambers of a water electrolysis device equipped with multiple water electrolysis chambers, wherein, Voltage sensors are installed in each of the multiple water electrolysis chambers. During the operation of the water electrolysis device, while water electrolysis is in progress, the voltage in each water electrolysis chamber is measured using these voltage sensors. If the voltage is found to be insufficient compared to the reference voltage, a short circuit is identified. To detect short circuits, the current density is reduced compared to the steady-state current density during water electrolysis to determine if a short circuit has occurred.

2. A short-circuit detection method for a water electrolysis device, comprising a method for detecting short circuits in the water electrolysis chambers of a water electrolysis device equipped with multiple water electrolysis chambers, wherein, A voltage sensor is installed in each of the n water electrolysis chambers. When the water electrolysis device is in operation, the voltage of the n water electrolysis chambers is measured by the voltage sensor. When the steady-state water electrolysis voltage is set to Vm and the reference voltage is set to Vb, if the detected voltage becomes less than (n-1)Vm+Vb, it is determined to be a short circuit.

3. A method for producing hydrogen, wherein, Hydrogen is generated by a water electrolysis device, and short circuit detection is performed by the short circuit detection method of the water electrolysis device as described in claim 1 or 2.

4. A water electrolysis apparatus, wherein hydrogen is obtained by water electrolysis in a water electrolysis chamber, wherein, The water electrolysis device has the following features: Multiple water electrolysis chambers; Voltage sensors are respectively installed in multiple water electrolysis chambers; and The controller obtains the voltage from the voltage sensor. If, during the operation of the water electrolysis device, hydrogen is being generated by water electrolysis in the water electrolysis chamber, and the obtained voltage is lower than the reference voltage, the controller will report a short circuit. To perform short-circuit detection, the controller periodically reduces the current density compared to the steady-state water electrolysis voltage to obtain the voltage.

5. A water electrolysis apparatus, wherein hydrogen is obtained by water electrolysis in a water electrolysis chamber, wherein, The water electrolysis device has the following features: Multiple water electrolysis chambers; Voltage sensors are provided for every n water electrolysis chambers; and The controller obtains the voltage from the voltage sensor. When the water electrolysis device is in operation, the controller measures the voltage of the n water electrolysis chambers through the voltage sensor. When the steady-state water electrolysis voltage is set to Vm and the reference voltage is set to Vb, a short circuit is reported when the voltage detected in the n water electrolysis chambers becomes less than (n-1)Vm+Vb.

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