Water electrolysis device, control method and program

Abstract

A water electrolysis apparatus includes: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path for circulatingly supplying electrolyte to the water electrolysis unit; a first temperature sensor for measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack; a second temperature sensor for measuring the outlet temperature of the electrolyte flowing at the outlet of a plurality of flow paths formed in the electrolysis section of the separator; and a control unit for controlling at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section based on the inlet temperature of the first temperature sensor and the outlet temperature of the second temperature sensor, so as to reduce the temperature that has been raised in a portion of the electrolysis section of the separator.

Description

Technical Field

[0001] This disclosure relates to a water electrolysis device, control method, and program. Prior Technology

[0002] A water electrolysis device uses water electrolysis cells to produce oxygen and hydrogen. Patent Document 1 discloses a water electrolysis system that measures the temperature of the water electrolysis stack or the temperature of the water discharged from the water electrolysis stack and uses a cooler to adjust the temperature of the water supplied to multiple water electrolysis stacks. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] International Publication No. 2023 / 012944 Summary of the Invention

[0004] [The problem the invention aims to solve] To improve electrolysis performance, it is necessary to increase the temperature of the electrolyte in the circulating water electrolysis unit. However, it is also necessary to keep the electrolyte temperature below the heat resistance temperature of the electrolyte membranes, such as the anion exchange membranes used in the water electrolysis unit.

[0005] This disclosure is a creation made to solve the above-mentioned problems, and its purpose is to provide a water electrolysis device, control method and program that can prevent the electrolyte membrane from breaking even if the temperature of the electrolyte rises. [Methods used to solve problems]

[0006] The water electrolysis apparatus disclosed herein comprises: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path that circulates the electrolyte to the water electrolysis unit; a first temperature sensor capable of measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack; a second temperature sensor capable of measuring the outlet temperature of the electrolyte flowing at the outlet of a plurality of flow paths formed in the electrolysis section of the separator; and a control unit that adjusts at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section based on the inlet temperature of the first temperature sensor and the outlet temperature of the second temperature sensor, thereby reducing the temperature that has been raised in a portion of the electrolysis section of the separator.

[0007] The water electrolysis apparatus disclosed herein comprises: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, and using the aforementioned water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the aforementioned water electrolysis stack; an electrolyte path that circulates the aforementioned electrolyte to the aforementioned water electrolysis unit; a first temperature sensor capable of measuring the inlet temperature of the aforementioned electrolyte flowing at the inlet of the aforementioned water electrolysis stack; a third temperature sensor capable of measuring the temperature of the outer surface of the aforementioned water electrolysis stack corresponding to the outlets of a plurality of flow paths formed in the aforementioned separator's electrolysis section; and a control unit that adjusts at least one of the flow rate, temperature, and current of the aforementioned electrolyte in the aforementioned electrolysis section based on the outlet temperature of the flow path flowing at the outlets of the plurality of aforementioned flow paths, which is estimated from the aforementioned inlet temperature and the aforementioned outer surface temperature, so that the temperature of a portion of the aforementioned electrolysis section in the aforementioned separator that has been raised decreases.

[0008] The control method disclosed herein is a control method for a water electrolysis device, which includes: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path that circulates the electrolyte to the water electrolysis unit; wherein the control method includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack using a first temperature sensor; measuring the outlet temperature of the electrolyte flowing at the outlet of a plurality of flow paths formed in the electrolysis section of the separator using a second temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section based on the inlet temperature and the outlet temperature of the flow path, so as to reduce the temperature that has been raised in a portion of the electrolysis section of the separator.

[0009] The control method disclosed herein is a control method for a water electrolysis device, which includes: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path that circulates the electrolyte to the water electrolysis unit; wherein the control method includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack using a first temperature sensor; measuring the temperature of the outer surface of the water electrolysis stack corresponding to the outlets of a plurality of flow paths formed in the electrolysis section of the separator using a third temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section based on the flow path outlet temperatures of the plurality of flow paths estimated from the inlet temperature and the temperature of the outer surface, so as to reduce the temperature that has been raised in a portion of the electrolysis section of the separator.

[0010] The program disclosed herein enables a water electrolysis apparatus to perform the following steps. The water electrolysis apparatus comprises: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, using the aforementioned water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the aforementioned water electrolysis stack; and an electrolyte path that circulates the aforementioned electrolyte to the aforementioned water electrolysis unit. The aforementioned steps include: measuring the inlet temperature of the aforementioned electrolyte flowing at the inlet of the aforementioned water electrolysis stack using a first temperature sensor; measuring the outlet temperature of the aforementioned electrolyte flowing at the outlet of a plurality of flow paths formed in the electrolysis section of the aforementioned separator using a second temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the aforementioned electrolyte in the aforementioned electrolysis section based on the aforementioned inlet temperature and the aforementioned outlet temperature, so that the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator decreases.

[0011] The program disclosed herein enables a water electrolysis apparatus to perform the following steps. The water electrolysis apparatus comprises: a water electrolysis stack having a water electrolysis unit with a solid polymer electrolyte membrane disposed between a pair of separators, using the aforementioned water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the aforementioned water electrolysis stack; and an electrolyte path that circulates the aforementioned electrolyte to the aforementioned water electrolysis unit. The aforementioned steps include: measuring the inlet temperature of the aforementioned electrolyte flowing at the inlet of the aforementioned water electrolysis stack using a first temperature sensor; measuring the temperature of the outer surface of the aforementioned water electrolysis stack corresponding to the outlets of a plurality of flow paths formed in the electrolysis section of the aforementioned separator using a third temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the aforementioned electrolyte in the aforementioned electrolysis section based on the flow path outlet temperatures estimated from the aforementioned inlet temperature and the aforementioned outer surface temperature, thereby reducing the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator. [Invention Effects]

[0012] According to this disclosure, even if the temperature of the electrolyte rises, damage to the electrolyte membrane can be prevented in advance. Simple Explanation of the Diagram

[0013] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of the water electrolysis apparatus according to the first embodiment. [Figure 2] Figure 2 is an exploded view showing an example of the structure of a water electrolysis unit. [Figure 3] Figure 3 is a diagram showing an example of the configuration of a separator. [Figure 4] Figure 4 is a graph showing the relationship between the temperature difference between the flow path and the unit inlet under the current density of 1 A / cm2 in the electrolysis test. [Figure 5] Figure 5 is a graph showing the relationship between the temperature difference between the flow path and the unit inlet under the current density of 3A / cm2 in the electrolysis test. [Figure 6] Figure 6 is a partial perspective view illustrating an example of the configuration of a temperature sensor in a water electrolysis device. [Figure 7] Figure 7 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the first embodiment. [Figure 8] Figure 8 is a flowchart illustrating an example of the processing sequence of the control method performed by the water electrolysis apparatus of the first embodiment. [Figure 9] Figure 9 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the second embodiment. [Figure 10] Figure 10 is a graph showing the temperature of the internal and external surfaces of a water electrolyzer. [Figure 11] Figure 11 is a schematic diagram showing an example of a water electrolysis stack consisting of multiple stacked water electrolysis units. [Figure 12] Figure 12 is a flowchart showing an example of the processing sequence of the control method performed by the water electrolysis apparatus of the second embodiment. [Figure 13] Figure 13 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the third embodiment. [Figure 14] Figure 14 is a graph showing the relationship between the elapsed time after the start of electrolysis and the measured temperature. [Figure 15] Figure 15 is a flowchart showing an example of the processing sequence of the control method performed by the water electrolysis apparatus of the third embodiment at the start of electrolysis. Implementation

[0014] Hereinafter, embodiments suitable for this disclosure will be described in detail with reference to the accompanying drawings. Furthermore, this disclosure is not limited to these embodiments; in cases where multiple embodiments exist, combinations of these embodiments may also be used.

[0015] (First Embodiment) (Overall structure of a water electrolysis unit) Figure 1 is a schematic diagram showing the general configuration of the water electrolysis apparatus according to the first embodiment. As shown in Figure 1, the water electrolysis apparatus 1 according to the first embodiment includes: a water electrolysis unit 11, a power supply unit 12, a first electrolyte path 14, a first gas-liquid separation tank 15, an oxygen extraction path 16, a second electrolyte path 17, a second gas-liquid separation tank 18, a hydrogen extraction path 19, an adjustment unit 60, and a control unit 70. Furthermore, the water electrolysis apparatus 1 is provided with a first water supply path 41 for pressurizing the electrolyte in the first electrolyte path 14, and a first water supply valve 42. The electrolyte includes circulating electrolyte. Moreover, a second water supply path 43 for pressurizing the electrolyte in the second electrolyte path 17, and a second water supply valve 44 are provided.

[0016] The water electrolysis unit 11 is located within the water electrolysis stack 21, with an anode disposed on one side of a hydrogen ion-permeable solid polymer electrolyte membrane 22 and a cathode disposed on the other side. The solid polymer electrolyte membrane 22 can be, for example, an ion exchange membrane such as an anion exchange membrane. The water electrolysis unit 11 is constructed by stacking an odd number or a plurality of these units within the water electrolysis stack 21. The water electrolysis unit 11 electrolyzes the electrolyte using the solid polymer electrolyte membrane 22 to generate oxygen on the anode side 23 and hydrogen on the cathode side 24.

[0017] The power supply unit 12 supplies power (current) to the anode and cathode on both sides of the solid polymer electrolyte membrane 22 disposed in the water electrolysis unit 11. The power supply unit 12 can be, for example, a DC power supply or a power supply device utilizing natural energy.

[0018] The control unit 70 supplies power to the water electrolysis unit 11 and performs water electrolysis by controlling the current and voltage values ​​of the power input from the power supply unit 12 and the power supplied to the anode and cathode on both sides of the solid polymer electrolyte membrane 22 disposed on the water electrolysis unit 11, thereby producing oxygen and hydrogen.

[0019] The first electrolyte path 14 enables the electrolysis of the electrolyte (water) by circulating the electrolyte to the water electrolysis reactor 21 and supplying the electrolyte to the anode side 23 of the water electrolysis unit 11. The first electrolyte path 14 is connected to the first gas-liquid separator 15. The first electrolyte path 14 has an inlet path 14a to the water electrolysis reactor 21 and an outlet path 14b from the water electrolysis reactor 21. The inlet path 14a of the first electrolyte path 14 is equipped with a first circulation pump 31. In this embodiment, the first electrolyte path 14 and the first gas-liquid separator 15 constitute the first electrolyte path.

[0020] The first gas-liquid separator 15 is a device for separating and removing oxygen that exists in the circulating electrolyte (water) in the form of bubbles or dissolved oxygen. At the top, an oxygen extraction path 16 for discharging the separated oxygen is connected. The first gas-liquid separator 15 is equipped with a filter 15a, through which impurities (e.g., dissolved metals) generated by the electrolysis of water are removed before the water is supplied to the water electrolysis reactor 21.

[0021] The second electrolyte path 17 circulates the electrolyte to the water electrolysis reactor 21 and supplies it to the cathode side 24 of the water electrolysis unit 11, thereby enabling the cooling of the solid polymer electrolyte membrane 22 and the extraction of hydrogen. The second electrolyte path 17 is connected to the second gas-liquid separator 18. The second electrolyte path 17 has an inlet path 17a to the water electrolysis reactor 21 and an outlet path 17b from the water electrolysis reactor 21. A second circulation pump 32 is provided in the inlet path 17a of the second electrolyte path 17. In this embodiment, the second electrolyte path 17 and the second gas-liquid separator 18 constitute the second electrolyte path.

[0022] The second gas-liquid separator 18 is a device for separating and removing hydrogen gas that exists in the circulating electrolyte (water) in the form of bubbles or dissolved gases. At its upper part, a hydrogen extraction path 19 for discharging the separated hydrogen gas is connected. The second gas-liquid separator 18 is equipped with a hydrogen control valve 33 in the hydrogen extraction path 19. A filter 18a is built into the second gas-liquid separator 18 to remove impurities generated by the electrolysis of water before supplying the hydrogen to the water electrolysis stack 21.

[0023] The inlet path 17a in the second electrolyte path 17 is connected to the buffer tank 35 via the auxiliary path 34. The auxiliary path 34 is equipped with a water discharge valve 36. The buffer tank 35 is used to temporarily hold the electrolyte according to the amount of hydrogen in the second gas-liquid separator 18 in the second electrolyte path 17.

[0024] The first water supply path 41, by supplying electrolyte from the outside to the first gas-liquid separator 15, can control the pressure of the first electrolyte path 14 and the first gas-liquid separator 15 on the anode side 23 of the water electrolysis reactor 21. A first water supply valve 42 is provided in the first water supply path 41 to adjust the water supplied to the first gas-liquid separator 15. Furthermore, a water supply pump (not shown) is provided in the first water supply path 41. The electrolyte supplied from the first water supply path 41 is a solution in which ionic substances are dissolved in pure water; however, an electrolyte pre-dissolved in oxygen may also flow in.

[0025] The second water supply path 43, by supplying water from the outside into the second gas-liquid separator 18, can control the pressure of the second electrolyte path 17 and the second gas-liquid separator 18 on the cathode side 24 of the water electrolysis reactor 21. A second water supply valve 44 is provided in the second water supply path 43 to adjust the water supplied to the second gas-liquid separator 18. Furthermore, a water supply pump (not shown) is provided in the second water supply path 43. In addition, the water supplied from the second water supply path 43 is pure water; however, electrolyte pre-dissolved in hydrogen can also flow into it.

[0026] An adjustment unit 60 is provided near the electrolyte inlets in the anode side 23 and cathode side 24 of the water electrolysis unit 11, enabling adjustment of the temperature of the electrolyte supplied to the water electrolysis unit 11. The adjustment unit 60 may include, for example, an air-cooled or water-cooled cooler capable of adjusting the electrolyte temperature. In this embodiment, the adjustment unit 60 is provided in the first electrolyte path 14 and the second electrolyte path 17, and is electrically connected to the control unit 70. The adjustment unit 60, controlled by the control unit 70, adjusts the rise or fall of the electrolyte temperature supplied to the water electrolysis unit 11, thus maintaining the electrolyte at a constant temperature.

[0027] The control unit 70 can control the current and voltage values ​​of the anode and cathode on both sides of the solid polymer electrolyte membrane 22 disposed in the water electrolysis unit 11 based on the power supplied by the power supply unit 12. The control unit 70 can adjust the discharge pressure (pump motor speed) of the first circulation pump 31 and the second circulation pump 32, and can adjust the opening degree (0~100%) of the hydrogen control valve 33 and the water discharge valve 36. The control unit 70 can adjust the opening degree (0~100%) of the first water supply valve 42 and the second water supply valve 44. The control unit 70 adjusts the temperature and flow rate of the electrolyte supplied to the water electrolysis unit 11 by controlling the adjustment unit 60.

[0028] Next, the function during startup of the water electrolysis apparatus 1 of the first embodiment will be explained.

[0029] After the operator inputs the start switch of the water electrolysis device 1, the control unit 70 first opens the first water supply valve 42 and the second water supply valve 44, supplying electrolyte to the first electrolyte path 14 and the second electrolyte path 17 of the anode and cathode of the water electrolysis unit 11 through the first water supply path 41 and the second water supply path 43. Simultaneously, the control unit 70 starts the first circulation pump 31 and the second circulation pump 32 to allow the electrolyte to flow. The control unit 70 then supplies power to the water electrolysis unit 11 to initiate the electrolysis reaction. At this time, the control unit 70 closes the hydrogen extraction path 19 using the hydrogen control valve 33 to keep the second electrolyte path 17 in a sealed state. Furthermore, the control unit 70 controls the flow rate of the electrolyte in the first circulation pump 31 and the second circulation pump 32 based on the current supplied to the water electrolysis unit 11.

[0030] The control unit 70 controls the current and voltage values ​​supplied to the anode and cathode disposed on both sides of the solid polymer electrolyte membrane 22 to electrolyze the electrolyte on the anode side 23 through the anode and cathode disposed on both sides of the solid polymer electrolyte membrane 22. That is, by supplying electrolyte to the anode and cathode disposed on both sides of the solid polymer electrolyte membrane 22 on the anode side 23 of the water electrolysis unit 11, a reaction occurs on the cathode side 24 of the solid polymer electrolyte membrane 22, producing hydrogen gas and hydroxide ions (OH-). Due to the potential difference between the anode side 23 and the cathode side 24, the hydroxide ions (OH-) move from the cathode side 24 through the solid polymer electrolyte membrane 22 to the anode side 23 along with water, where they react to produce oxygen.

[0031] The control unit 70 monitors the electrolyte pressure in the first electrolyte path 14 and the second electrolyte path 17 of the anode and cathode, and shuts off the first electrolyte path 14 and the second electrolyte path 17 when the predetermined electrolyte pressure is reached. Furthermore, the electrolyte pressure in the first electrolyte path 14 and the second electrolyte path 17 is detected by a pressure sensor (not shown). In this case, because the electrolyte pressure in the second electrolyte path 17 is higher than the constant pressure, hydrogen gas easily dissolves into the electrolyte in the water electrolysis device 1. Therefore, in the water electrolysis device 1, the hydrogen gas generated on the cathode side 24 circulates in the second electrolyte path 17 in a dissolved state.

[0032] When the hydrogen produced by the water electrolysis device 1 dissolves into the electrolyte, increasing the amount of hydrogen dissolved, it reaches saturation within a predetermined time. After this point, no more hydrogen dissolves in the water. Therefore, when the amount of hydrogen dissolved in the electrolyte of the second electrolyte path 17 exceeds saturation, the control unit 70 opens the hydrogen control valve 33. This increases the pressure in the hydrogen extraction path 19, thereby increasing the amount of hydrogen obtained. Then, when the amount of hydrogen obtained exceeds a preset amount, the control unit 70 sets the opening degree of the hydrogen control valve 33 to a constant value. In this way, the water electrolysis device 1 can stably obtain a predetermined amount of hydrogen at a predetermined pressure.

[0033] (Composition of a water electrolysis unit) Figure 2 is an exploded view showing an example of the configuration of a water electrolysis unit. Figure 3 is a diagram showing an example of the configuration of a separator. Furthermore, in the example shown in Figure 2, a single water electrolysis unit 11 is shown for the sake of simplicity; however, it is also possible to have a configuration of multiple units stacked together.

[0034] As shown in Figure 2, the water electrolysis unit 11 includes: a pair of separators 25 and 26, a solid polymer electrolyte membrane 22 disposed between the pair of separators 25 and 26, and power supply units 27 and 28 disposed between the solid polymer electrolyte membrane 22 and the pair of separators 25 and 26. The water electrolysis unit 11 also includes: a catalyst layer 51 between the power supply unit 27 on the anode side 23 and the solid polymer electrolyte membrane 22, and a catalyst layer 52 between the power supply unit 28 on the cathode side 24 and the solid polymer electrolyte membrane 22. The catalyst layer 51 is an oxygen electrode catalyst layer for the separator 25 on the anode side 23. The catalyst layer 52 is a hydrogen electrode catalyst layer for the separator 26 on the cathode side 24. The water electrolysis unit 11 is stacked in the following order from the anode side 23 to the cathode side 24: separator 25, power supply 27, catalyst layer 51, solid polymer electrolyte membrane 22, catalyst layer 52, power supply 28, and separator 25, forming a multi-layer stacked structure.

[0035] A pair of separators 25 and 26 are formed into rectangular plates using metal components that do not allow oxygen and hydrogen produced during water electrolysis to pass through. Each separator 25 and 26 has an inlet pipe 29a serving as an inlet for the electrolyte and an outlet pipe 29b serving as an outlet for the electrolyte. The inlet pipes 29a are respectively connected to the inlet path 14a of the first electrolyte path 14 and the inlet path 17a of the second electrolyte path 17. The outlet pipes 29b are respectively connected to the outlet path 14b of the first electrolyte path 14 and the outlet path 17b of the second electrolyte path 17.

[0036] As shown in Figure 3, a pair of separators 25 and 26 each have: a body 200, an electrolysis section 210 formed in the center of the body 200, an electrolyte inlet 220 provided on one side of the electrolysis section 210, and an electrolyte outlet 230 provided on the other side of the electrolysis section 210. The electrolyte inlet 220 and electrolyte outlet 230 of the separators 25 and 26 are arranged diagonally in the body 200, with the electrolysis section 210 located between them. The body 200 has two opposing fixing parts 201, which are fixed in a stacked position by means of fixing members passing through the fixing parts 201.

[0037] The electrolysis section 210 is a region within the plane of the main body 200, and is the region where the power supply bodies 27 and 28 are stacked (in contact). The electrolysis section 210 has multiple flow paths 211 for flowing the electrolyte (pure water) that is electrolyzed on the outside of the power supply bodies 27 and 28. The multiple flow paths 211 are arranged at equal intervals along the width direction W of the separators 25 and 26, and are formed as multiple channels extending along the longitudinal direction F. The multiple flow paths 211 are the sections in the electrolysis section 210 where the electrolyte and gas flow. The longitudinal direction F is the direction in which the electrolyte flows in the electrolysis section 210, and is orthogonal to the width direction W. The closer the multiple flow paths 211 are to the electrolyte inlet 220, the faster the electrolyte flow rate; the farther away, the slower the electrolyte flow rate.

[0038] The electrolyte inlet 220 is a hole formed near a corner on one side of the electrolysis section 210 in a region 200A surrounding the body 200, and communicates with the inlet pipe 29a of the separator 25 or separator 26. The electrolyte inlet 220 supplies electrolyte from the inlet pipe 29a to all of the multiple flow paths 211 of the electrolysis section 210.

[0039] The electrolyte outlet 230 is a hole formed near a corner on the other side of the electrolysis section 210 in a region 200B surrounding the body 200, facing the electrolyte inlet 220, and communicates with the outlet pipe 29b of the separator 25 or separator 26. The electrolyte outlet 230 discharges the electrolyte that has flowed through the multiple flow paths 211 of the electrolysis section 210 and converged into the outlet pipe 29b.

[0040] A pair of separators 25 and 26 surround the electrolysis section 210, the electrolyte inlet 220, and the electrolyte outlet 230 with a gasket 240 to restrict the flow of electrolyte. In this way, the pair of separators 25 and 26, through the gasket 240, improve the efficiency of electrolyte supply from the electrolyte inlet 220 to the electrolysis section 210 and electrolyte discharge from the electrolysis section 210 to the electrolyte outlet 230.

[0041] A pair of separators 25 and 26 separate the electrolyte from the electrolyte inlet 220 into multiple flow paths 211 of the electrolysis section 210, directing it in flow directions such as L1, L2, and L3. Then, the electrolyte flowing through each of the multiple flow paths 211 is recombined at the outlets of the multiple flow paths 211 and flows into the electrolyte outlet 230. The electrolyte in flow direction L1 flows faster than the electrolyte in flow direction L2. The electrolyte in flow direction L2 flows faster than the electrolyte in flow direction L3.

[0042] The power supply units 27 and 28 use a metal mesh and are formed to be stacked with the electrolysis section 210 of the separators 25 and 26 and the catalyst layers 51 and 52. The power supply units 27 and 28 are configured to supply power from the power supply unit 12 through end plates disposed on the outside of the water electrolysis unit 11.

[0043] (Water electrolysis reaction in the water electrolysis unit) As shown in Figure 2, the water electrolysis unit 11 supplies electrolyte (H2O) to the separator 25 on the anode side 23 and the separator 26 on the cathode side 24, and applies voltage to the power supply units 27 and 28. In the water electrolysis unit 11, on the cathode side 24, as shown in the following (Equation 1), the electrolyte (H2O) flowing through the multiple flow paths 211 of the separator 26 reacts in the catalyst layer 52, resulting in a water reduction reaction. Hydrogen (H2) and hydroxide ions (OH-) are generated from the electrolyte (H2O). The hydroxide ions (OH-) move towards the anode side 23 through the interior of the solid polymer electrolyte membrane 22.

[0044] Then, in the water electrolysis unit 11, on the anode side 23, as shown in the following (Equation 2), hydroxyl radicals (OH-) that have moved from inside the solid polymer electrolyte membrane 22 generate oxygen (O2) and water (H2O) in the catalyst layer 51.

[0045] From Equations (1) and (2), the overall reaction is shown in Equation (3) below, which is the generation of oxygen and hydrogen from water.

[0046] The water electrolysis unit 11 discharges an electrolyte containing oxygen (O2+H2O) from the outlet pipe 29b via the separator 25 on the anode side 23, and an electrolyte containing hydrogen (H2+H2O) from the outlet pipe 29b via the separator 26 on the cathode side 24.

[0047] In order to improve the performance of the water electrolysis unit 11, it is necessary to increase the temperature of the electrolyte in the water electrolysis apparatus 1. However, when the solid polymer electrolyte membrane 22 is an anion exchange membrane, it is necessary to keep it below the heat resistance temperature. In this embodiment, the water electrolysis apparatus 1 implements a technique to suppress the rise in temperature of the solid polymer electrolyte membrane 22 and improve the performance of the water electrolysis unit 11.

[0048] (Separator flow path) Next, the test results of electrolysis experiments using model separators 25 and 26 of the water electrolysis unit 11 will be explained. The model separators differ from the actual separators 25 and 26 in the width and number of flow paths 211 (channels).

[0049] Figure 4 is a graph showing the relationship between the temperature difference between the flow path and the unit inlet when the current density is 1 A / cm² under electrolysis test conditions. Figure 5 is a graph showing the relationship between the temperature difference between the flow path and the unit inlet when the current density is 3 A / cm² under electrolysis test conditions. Furthermore, current density is the amount of electric charge flowing per unit time in the power supply bodies 27 and 28 in a direction perpendicular to the unit area.

[0050] Figures 4 and 5 show the results of measuring the outlet temperatures of multiple flow paths 211 in the separator 26 on the cathode side 24 of the water electrolysis unit 11 using a temperature sensor. The outlet temperature is the temperature near the outlet of the flow path 211 where the electrolyte flows. In Figures 4 and 5, the temperature difference (°C) between the inlet temperature of the separator 26 and the outlet temperatures of the multiple flow paths 211 is displayed on the vertical axis. In Figures 4 and 5, the flow path numbers assigned to the multiple flow paths 211 in the width direction W of the electrolysis section 210, moving away from the side near the electrolyte inlet 220, are displayed on the horizontal axis. Figures 4 and 5 show the results measured at four measurement points of the model separator, corresponding to points P1 to P4 near the outlet of the flow path 211 shown in Figure 3.

[0051] Figure 4 shows graphs G11 and G13, which represent the temperature difference between the inlet temperature of the separator 26 and the outlet temperature of the flow path 211 measured at four measurement points under the current density of 1 A / cm² in the electrolysis test, when the flow rate of the electrolyte in the water electrolysis unit 11 changes to 0.8 kg / (min·cell) and 1.5 kg / (min·cell). That is, the electrolyte flow rate decreases according to the order of graphs G13 and G11. The measurement results shown in Figure 4 show that the exothermic effect is significant in the electrolysis section 210 of the separator 26, and the temperature difference is large on the outer side in the width direction W. The measurement results shown in Figure 4 also show that the outlet temperature of multiple flow paths 211 is lower than the inlet temperature of the separator 26, and the temperature difference is negative.

[0052] Figures 5, G31 and G32, show the temperature difference between the inlet temperature of the separator 26 and the outlet temperature of the flow path 211 measured at four measurement points under the current density of 3 A / cm² in the electrolysis test, when the flow rate of the electrolyte in the water electrolysis unit 11 is varied to 1.5 kg / (min·cell) and 3.0 kg / (min·cell). That is, the electrolyte flow rate decreases according to the order of G32 and G31. The measurement results shown in Figure 5 indicate that the maximum temperature difference in the width direction W of the electrolysis section 210 of the separator 26 is 13°C, and the lower the electrolyte flow rate, the greater the temperature difference.

[0053] In this way, the results of the electrolysis test show that when the current density of the water electrolysis unit 11 increases, the temperature distribution (temperature difference) in the width direction W of the separator 26 tends to increase. That is, it is determined that the electrolysis section 210 of the separators 25 and 26 has a temperature distribution, and this temperature distribution changes with the current density. For example, if there is a localized temperature rise in the electrolysis section 210 of the separators 25 and 26, it may be impossible to detect the abnormality by only measuring the electrolyte temperature at the stack outlet of the water electrolysis stack 21. In this way, the water electrolysis device 1 related to this embodiment achieves the suppression of the temperature rise of the solid polymer electrolyte membrane 22, the improvement of the performance of the water electrolysis unit 11, and the prevention of damage to the solid polymer electrolyte membrane 22. In detail, the water electrolysis device 1 prevents damage to the solid polymer electrolyte membrane 22 by measuring the electrolyte temperature near the outlet of the flow path 211 of the water electrolysis unit 11 at multiple locations and controlling the electrolyte temperature when there is a localized temperature rise.

[0054] (Temperature sensor of water electrolysis device) Figure 6 is a partial perspective view illustrating an example of the configuration of the temperature sensor in the water electrolysis apparatus. Figure 7 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the first embodiment. Furthermore, in Figure 6, the flow direction of the electrolyte is indicated by the direction L shown by the arrow.

[0055] In one example shown in Figure 6, the water electrolysis unit 11 is held between two end plates 20. The end plate 20 on the anode side 23 connects the inlet path 14a and the outlet path 14b, and the end plate 20 on the cathode side 24 connects the inlet path 17a and the outlet path 17b. In this embodiment, when the solid polymer electrolyte membrane 22 of the water electrolysis unit 11 is an anion exchange membrane, and the heat resistance temperature of the anion exchange membrane is, for example, 80°C, the water electrolysis device 1 adjusts the temperature of the electrolyte so that the inlet temperature of the water electrolysis unit 11 is below 75.5°C.

[0056] The water electrolysis apparatus 1 further includes: a first temperature sensor 81 for measuring the inlet temperature of the electrolyte flowing to the inlet of the water electrolysis stack 21; and a second temperature sensor 82 for measuring the outlet temperature of the electrolyte flowing through the outlets of the plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25 and 26. The first temperature sensor 81 is disposed on the inlet paths 14a and 17a of the water electrolysis stack 21 of the water electrolysis unit 11 and is electrically connected to the control unit 70. The second temperature sensor 82 is disposed at the outlet of the flow path 211 of the separators 25 and 26 of the water electrolysis unit 11 and is electrically connected to the control unit 70. The first temperature sensor 81 and the second temperature sensor 82 can be, for example, thermistors, resistance temperature sensors, thermocouples, etc. The first temperature sensor 81 and the second temperature sensor 82 supply the measured temperature information of the identifiable electrolyte temperature to the control unit 70.

[0057] In one example shown in Figure 7, the water electrolysis device 1 includes a control unit 70, a first temperature sensor 81, and a second temperature sensor 82; other components are omitted.

[0058] The second temperature sensor 82 includes second temperature sensors 82a, 82b, and 82c. Second temperature sensor 82a measures the outlet temperature of the flow path in the electrolysis section 210 of separators 25 and 26 in the flow direction L1. Second temperature sensor 82b measures the outlet temperature of the flow path in the electrolysis section 210 of separators 25 and 26 in the flow direction L2. Second temperature sensor 82c measures the outlet temperature of the flow path in the electrolysis section 210 of separators 25 and 26 in the flow direction L3. Furthermore, in the following description, when it is not necessary to distinguish between second temperature sensors 82a, 82b, and 82c, only second temperature sensor 82 will be referred to.

[0059] The control unit 70 is a computing device, namely a CPU (Central Processing Unit). The control unit 70 implements various functions and performs its processing by reading and executing programs (software) from the memory unit 72. Furthermore, the control unit 70 can be processed by a single CPU, or it can have multiple CPUs, with processing performed by these multiple CPUs. In this embodiment, the control unit 70 is electrically connected to the memory unit 72, but it can also be configured to have the memory unit 72 built-in.

[0060] The memory unit 72 is a memory that stores various information such as the computational content and programs of the control unit 70, including at least one of main memory devices such as RAM and ROM, and external memory devices such as HDD. The memory unit 72 can store programs 721, temperature information 722, etc. Program 721 includes a program for implementing water electrolysis-related control of the water electrolysis device 1. Temperature information 722 includes information that can identify the inlet temperature of the first temperature sensor 81 and the flow path outlet temperatures T1, T2, T3, etc. of multiple second temperature sensors 82. Flow path outlet temperature T1 is the temperature measured by the second temperature sensor 82a. Flow path outlet temperature T2 is the temperature measured by the second temperature sensor 82b. Flow path outlet temperature T3 is the temperature measured by the second temperature sensor 82c. The memory unit 72 stores multiple pieces of temperature information 722 sequentially. The temperature information 722, arranged in chronological order, can identify changes in temperature distribution and high-temperature regions in the electrolysis section 210 of separators 25 and 26 based on the flow path outlet temperatures of multiple second temperature sensors 82.

[0061] The control unit 70 adjusts the temperature of the electrolysis section 210 based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82, thereby reducing the temperature rise of the electrolysis section 210 in separators 25 and 26. The control unit 70 estimates the temperature distribution of the electrolysis section 210 in separators 25 and 26 based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82, and extracts regions in the electrolysis section 210 where the temperature locally rises. The control unit 70 performs control to adjust the electrolyte temperature, keeping the temperature of the electrolysis section 210 in separators 25 and 26 below the heat resistance temperature of the solid polymer electrolyte membrane 22. The control unit 70 controls the adjustment unit 60 based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82, thereby keeping the temperature of the electrolysis section 210 in separators 25 and 26 below the heat resistance temperature of the solid polymer electrolyte membrane 22.

[0062] (Regarding the control method of the water electrolysis apparatus of the first embodiment) Figure 8 is a flowchart illustrating an example of the processing sequence of the control method executed by the water electrolysis apparatus of the first embodiment. The processing steps shown in Figure 8 are implemented by the control unit 70 of the water electrolysis apparatus 1 executing program 721.

[0063] As shown in Figure 8, the control unit 70 of the water electrolysis apparatus 1 measures the flow path outlet temperatures T1, T2, and T3 in the electrolysis section 210 of separators 25 and 26 (step S101). For example, the control unit 70 obtains the flow path outlet temperatures T1, T2, and T3 measured by the second temperature sensor 82 and stores them as temperature information 722 in the memory unit 72. After the processing in step S101 is completed, the control unit 70 proceeds to step S102.

[0064] The control unit 70 determines whether the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature (step S102). For example, when the first heat resistance temperature of the solid polymer electrolyte membrane 22 is 80°C, the control unit 70 will determine that the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature if all three are above 80°C. When the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature (step S102 is "Yes"), the process proceeds to step S103.

[0065] The control unit 70 reduces the current or stops the electrolysis operation (step S103). For example, since the outlet temperatures T1, T2, and T3 are above the first heat resistance temperature, the control unit 70 reduces the current (current density). Alternatively, the control unit 70 stops the electrolysis operation in the water electrolysis device 1. Here, since the temperature of the electrolysis section 210 of the water electrolysis device 1 is generally above the first heat resistance temperature, the temperature of the electrolysis section 210 is lowered by reducing the current or stopping the electrolysis operation. After the control unit 70 completes the process in step S103, it proceeds to step S109, which will be described later.

[0066] Furthermore, if the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are not above the first heat resistance temperature (step S102 is "No"), it proceeds to step S104. The control unit 70 determines whether the flow path outlet temperatures T1, T2, and T3 are above the second heat resistance temperature (step S104). For example, when the second heat resistance temperature of the solid polymer electrolyte membrane 22 is lower than the first heat resistance temperature, at 75°C, the control unit 70 will determine that the flow path outlet temperatures T1, T2, and T3 are above the second heat resistance temperature if all three are above 75°C. If the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are not above the second heat resistance temperature (step S104 is "No"), since the flow path outlet temperatures T1, T2, and T3 are normal, it proceeds to step S110, which will be described later. In addition, when the control unit 70 determines that the outlet temperatures T1, T2, and T3 of the flow path are above the second heat resistance temperature (step S104 is "Yes"), the process is advanced to step S105.

[0067] The control unit 70 determines whether the condition "flow path outlet temperature T2 ≥ flow path outlet temperature T1" or "flow path outlet temperature T3 ≥ flow path outlet temperatures T1 and T2" is met (step S105). For example, when the flow path outlet temperature T2 ≥ flow path outlet temperature T1 or the flow path outlet temperature T3 ≥ flow path outlet temperatures T1 and T2, multiple flow paths 211 in the electrolysis section 210 of separators 25 and 26 may be partially blocked. Therefore, the control unit 70 determines whether the flow paths 211 in the electrolysis section 210 of separators 25 and 26 are blocked by determining whether the condition "flow path outlet temperature T2 ≥ flow path outlet temperature T1" or "flow path outlet temperature T3 ≥ flow path outlet temperatures T1 and T2" is met.

[0068] When the control unit 70 determines that the outlet temperature T2 is greater than or equal to the outlet temperature T1, or the outlet temperature T3 is greater than or equal to the outlet temperatures T1 and T2 (step S105 is "Yes"), it proceeds to step S106. That is, when the flow path 211 is blocked, even if the electrolyte flow rate is increased, the electrolyte cannot flow easily through the blocked flow path 211, therefore the control unit 70 proceeds to step S106. The control unit 70 lowers the electrolyte temperature (step S106). For example, based on the inlet temperature of the separator 26 measured by the first temperature sensor 81 and the outlet temperatures of the multiple flow paths 211 measured by the second temperature sensor 82, the control unit 70 lowers the electrolyte temperature through the control adjustment unit 60 to achieve the desired temperature. In this way, because the temperature of the electrolysis unit 210 is locally higher in the water electrolysis device 1, the temperature of the electrolysis unit 210 is lowered by lowering the electrolyte temperature. After the control unit 70 finishes processing in step S106, it proceeds to step S109, which will be described later.

[0069] Furthermore, if the control unit 70 determines that the flow path outlet temperature T2 is not greater than or equal to the flow path outlet temperature T1, or the flow path outlet temperature T3 is not greater than or equal to the flow path outlet temperatures T1 and T2 (step S105 is "No"), the process proceeds to step S107. The control unit 70 determines whether the electrolyte flow rate has reached its upper limit (step S107). For example, when there are multiple water electrolysis stacks 21 in the water electrolysis device 1 with high temperatures due to reasons such as aging of the solid polymer electrolyte membrane 22, it is necessary to lower the temperature of the water electrolysis stacks 21. Therefore, the water electrolysis device 1 determines whether the electrolyte flow rate has reached its upper limit.

[0070] When the control unit 70 determines that the flow rate of the electrolyte flowing through the water electrolysis unit 11 has reached its upper limit (step S107 is "Yes"), it proceeds to the previously described step S106. Next, the control unit 70 lowers the temperature of the electrolyte (step S106). After the processing in step S106 is completed, the control unit 70 proceeds to the step S109, which will be described later.

[0071] Furthermore, when the control unit 70 determines that the flow rate of the electrolyte flowing through the water electrolysis unit 11 has not yet reached its upper limit (step S107 is "No"), it proceeds to step S108. The control unit 70 increases the flow rate of the electrolyte (step S108). For example, in order to reduce the temperature of the water electrolysis stack 21, the control unit 70 increases the flow rate of the electrolyte supplied to the water electrolysis stack 21 via the first water supply path 41 and the second water supply path 43 by opening the first water supply valve 42 and the second water supply valve 44. Therefore, since the temperature of the electrolysis unit 210 is locally high, the temperature of the electrolysis unit 210 is reduced by increasing the flow rate of the electrolyte. After the control unit 70 completes the process in step S108, it proceeds to step S109.

[0072] The control unit 70 confirms that the electrolyte temperature has decreased (step S109). For example, the control unit 70 confirms that the electrolyte temperature has decreased to the required temperature based on the inlet temperature of the separator 26 measured by the first temperature sensor 81 and the outlet temperatures of the multiple flow paths 211 measured by the second temperature sensor 82. After confirming that the electrolyte temperature has decreased, the control unit 70 proceeds to step S110.

[0073] The control unit 70 determines whether to end the process (step S110). For example, the control unit 70 determines that the process is complete when conditions such as the completion of water electrolysis or an external end instruction are met. If the control unit 70 determines that the process is not complete (step S110 is "No"), it returns to the previously described step S101 to continue processing. Alternatively, if the control unit 70 determines that the process is complete (step S110 is "Yes"), it ends the processing steps shown in FIG8.

[0074] In this way, the water electrolysis device 1 uses the second temperature sensor 82 to measure the outlet temperature of the flow path at multiple different locations and adjusts the inlet temperature of the pair of separators 25 and 26 to control the temperature of the electrolysis section 210 to keep it below the heat resistance temperature of the solid polymer electrolyte membrane 22. Therefore, the water electrolysis device 1 can prevent the solid polymer electrolyte membrane 22 from being damaged by temperature rise when the temperature locally increases in the electrolysis section 210 of the pair of separators 25 and 26. As a result, the water electrolysis device 1 can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis.

[0075] Furthermore, the water electrolysis device 1 can control the temperature of the electrolysis section 210 of the pair of separators 25 and 26 to below the heat resistance temperature of the solid polymer electrolyte membrane 22 when the temperature rises locally, thus reliably preventing damage to the solid polymer electrolyte membrane 22.

[0076] (Second Implementation) Next, the second embodiment will be described. In the second embodiment, the basic structure of the water electrolysis device 1 is the same as that of the first embodiment, but the temperature measurement position is different from that of the first embodiment. In the second embodiment, the parts that are common to the first embodiment will be omitted from the description. The water electrolysis device 1 of the second embodiment includes: a water electrolysis unit 11, a power supply unit 12, a first electrolyte path 14, a first gas-liquid separation tank 15, an oxygen extraction path 16, a second electrolyte path 17, a second gas-liquid separation tank 18, a hydrogen extraction path 19, an adjustment unit 60, and a control unit 70.

[0077] Figure 9 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the second embodiment. As shown in Figure 9, the water electrolysis apparatus 1 according to the second embodiment further includes: a first temperature sensor 81; and a third temperature sensor 83 for measuring the temperature distribution near the outlet of the flow path 211 in the electrolysis section 210 of the separators 25 and 26; other configurations described above are omitted.

[0078] The third temperature sensor 83 is a temperature sensor capable of measuring the external surface temperature of a water electrolysis stack 21 corresponding to the outlets of the multiple flow paths 211 formed in the electrolysis section 210 of the separators 25 and 26. The water electrolysis stack 21 is formed of a thermally conductive component, and heat from the electrolysis section 210 of the separators 25 and 26 is transferred. The third temperature sensor 83 is disposed on the external surface of the water electrolysis stack 21 corresponding to the vicinity of the outlets of the flow paths 211 of the electrolysis section 210 of the separators 25 and 26, and is electrically connected to the control unit 70. The third temperature sensor 83 can be, for example, a thermistor, a resistance temperature sensor, or a thermocouple. The third temperature sensor 83 supplies temperature information 722, which identifies the external surface temperature of the water electrolysis stack 21, to the control unit 70.

[0079] Figure 10 is a graph showing the internal and external surface temperatures of the water electrolysis reactor 21. In Figure 10, the vertical axis represents the internal temperature of the water electrolysis reactor 21, and the horizontal axis represents the external surface temperature of the water electrolysis reactor 21.

[0080] Figure 10 shows graph G41, which illustrates the relationship between the internal temperature of the water electrolyzer 21 measured by the second temperature sensor 82a and the external surface temperature measured by the third temperature sensor 83. As shown in graph G41, the maximum temperature difference between the temperature near the outlet of the flow path 211 on the outside of the water electrolyzer 21 and the temperature inside the water electrolyzer 21 (i.e., near the outlet of the flow path 211 of separators 25 and 26) is 7°C. That is, graph G41 shows a proportional relationship between the external surface temperature measured by the third temperature sensor 83 and the internal temperature of the water electrolyzer 21.

[0081] The water electrolysis device 1 can estimate the temperature near the outlet of the flow path 211 in the electrolysis section 210 of the separators 25 and 26 based on the external surface temperature measured by the third temperature sensor 83 by pre-memorizing the estimation information 723 corresponding to the diagram G41 in the memory unit 72. The estimation information 723 includes information for estimating the flow path outlet temperature of multiple flow paths 211 and the temperature distribution near the outlet based on the external surface temperature of the water electrolysis reactor 21. For example, the estimation information 723 includes a lookup table for estimating the flow path outlet temperature of multiple flow paths 211 and the temperature distribution near the outlet from the temperature of the external surface of the water electrolysis reactor 21. For example, the estimation information 723 includes information of a machine learning model, which, after inputting the external surface temperature of the water electrolysis reactor 21, outputs the flow path outlet temperature of multiple flow paths 211 and the temperature distribution near the outlet.

[0082] Figure 11 is a schematic diagram showing an example of a water electrolysis stack 21 in which multiple water electrolysis units 11 are stacked. As shown in Figure 11, the water electrolysis stack 21 has multiple (e.g., 30 units) water electrolysis units 11 stacked along the stacking direction H, and is held by end plates 20 on both sides. In the example shown in Figure 11, the electrolyte flow rate of the water electrolysis units 11 near the center of the stacking direction H is relatively high, while the electrolyte flow rate of the water electrolysis units 11 near the end plates 20 is relatively low. Therefore, the water electrolysis device 1 provides a third temperature sensor 83 at three positions along the stacking direction H of the water electrolysis units 11, near the end plates 20 and at the center, but is not limited to this. For example, the number of third temperature sensors 83 can be set according to the number of water electrolysis units 11, temperature or flow characteristics, etc.

[0083] The water electrolysis device 1 stores the estimated information 723 corresponding to the water electrolysis unit 11, which is equipped with multiple third temperature sensors 83, in the memory unit 72. In this way, the water electrolysis device 1 can estimate the temperature distribution near the outlet of the flow path 211 in the electrolysis section 210 of the water electrolysis unit 11 at multiple different positions in the stacking direction H of the water electrolysis stack 21 based on the external surface temperature measured by the multiple third temperature sensors 83.

[0084] (Regarding the control method of the water electrolysis apparatus of the second embodiment) Figure 12 is a flowchart illustrating an example of the processing sequence of the control method executed by the water electrolysis apparatus according to the second embodiment. The processing steps shown in Figure 12 are implemented by the control unit 70 of the water electrolysis apparatus 1 executing program 721. In the processing steps shown in Figure 12, steps S102 to S110 are the same processing steps as those shown in Figure 8.

[0085] As shown in Figure 12, the control unit 70 of the water electrolysis device 1 measures the temperature of the outer surface of the water electrolysis stack 21 using the third temperature sensor 83 (step S121). For example, the control unit 70 obtains the outer surface temperature measured by the third temperature sensor 83 and stores it in the memory unit 72 as temperature information 722. After the processing in step S121 is completed, the control unit 70 proceeds to step S122.

[0086] The control unit 70 estimates the flow path outlet temperatures T1, T2, and T3 in the electrolysis section 210 of separators 25 and 26 based on the temperature of the external surfaces (step S122). For example, the control unit 70 estimates the flow path outlet temperatures T1, T2, and T3 in the electrolysis section 210 based on the external surface temperature measured in step S121 and the estimation information 723 in the memory unit 72, and stores them in the memory unit 72 as temperature information 722. After the processing in step S122 is completed, the control unit 70 proceeds to the previously described step S102.

[0087] The control unit 70 determines whether the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature (step S102). When the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature (step S102 is "yes"), the process proceeds to step S103.

[0088] The control unit 70 reduces the current or stops the electrolysis operation (step S103). After the processing in step S103 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0089] Furthermore, if the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are not above the first heat resistance temperature (step S102 is "No"), it proceeds to step S104. The control unit 70 then determines whether the flow path outlet temperatures T1, T2, and T3 are above the second heat resistance temperature (step S104). If the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are not above the second heat resistance temperature (step S104 is "No"), since the flow path outlet temperatures T1, T2, and T3 are normal, it proceeds to step S110 (described later). Alternatively, if the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are above the second heat resistance temperature (step S104 is "Yes"), it proceeds to step S105.

[0090] The control unit 70 determines whether the condition is "flow path outlet temperature T2 ≥ flow path outlet temperature T1" or "flow path outlet temperature T3 ≥ flow path outlet temperatures T1 and T2" (step S105). When the control unit 70 determines that the condition is "yes" (step S105 is "yes"), it proceeds to step S106. That is, when the flow path 211 is blocked, even if the electrolyte flow rate is increased, the electrolyte cannot flow easily through the blocked flow path 211, therefore the control unit 70 proceeds to step S106. The control unit 70 lowers the electrolyte temperature (step S106). After the process in step S106 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0091] Furthermore, when the control unit 70 determines that the flow path outlet temperature T2 is not greater than or equal to the flow path outlet temperature T1, or the flow path outlet temperature T3 is not greater than or equal to the flow path outlet temperatures T1 and T2 (step S105 is "No"), the process proceeds to step S107. The control unit 70 determines whether the electrolyte flow rate has reached its upper limit (step S107). When the control unit 70 determines that the electrolyte flow rate through the water electrolysis unit 11 has reached its upper limit (step S107 is "Yes"), the process proceeds to the previously described step S106. Next, the control unit 70 lowers the electrolyte temperature (step S106). After the process in step S106 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0092] Furthermore, when the control unit 70 determines that the flow rate of the electrolyte flowing through the water electrolysis unit 11 has not yet reached its upper limit (step S107 is "No"), it proceeds to step S108. The control unit 70 increases the flow rate of the electrolyte (step S108). After the processing in step S108 is completed, the control unit 70 proceeds to step S109.

[0093] The control unit 70 confirms that the electrolyte temperature has decreased (step S109). After confirming that the electrolyte temperature has decreased, the control unit 70 proceeds to step S110.

[0094] The control unit 70 determines whether to end the process (step S110). If the control unit 70 determines that the process should not end (step S110 is "No"), it returns to the previously explained step S121 to continue processing. Alternatively, if the control unit 70 determines that the process should end (step S110 is "Yes"), it ends the processing steps shown in FIG12.

[0095] In this way, the water electrolysis apparatus 1 of the second embodiment measures the external surface temperature of the water electrolysis stack 21 corresponding to the outlet of the flow path 211 of the electrolysis section 210 of the separators 25 and 26 by using the third temperature sensor 83, and estimates the flow path outlet temperature at multiple locations in the electrolysis section 210 of the separators 25 and 26 based on its external surface temperature. The water electrolysis apparatus 1 can adjust the temperature of the electrolysis section 210 according to the flow path outlet temperature at multiple locations, thereby reducing the temperature rise of the aforementioned electrolysis section of the separator. In this way, the water electrolysis apparatus 1 can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26 by controlling the temperature of the electrolyte. As a result, the water electrolysis apparatus 1 can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis. Furthermore, since the water electrolysis device 1 only needs to measure the external surface temperature of the water electrolysis stack 21, it is not necessary to install the third temperature sensor 83 on the electrolysis section 210 of the separators 25 and 26, thereby simplifying the device structure.

[0096] (Third Implementation) Next, the third embodiment will be described. In the third embodiment, the basic structure of the water electrolysis device 1 is the same as that of the first embodiment, but the temperature measurement position is different from that of the first embodiment. In the third embodiment, the parts that are common to the first embodiment will be omitted from the description. The water electrolysis device 1 of the third embodiment includes: a water electrolysis unit 11, a power supply unit 12, a first electrolyte path 14, a first gas-liquid separation tank 15, an oxygen extraction path 16, a second electrolyte path 17, a second gas-liquid separation tank 18, a hydrogen extraction path 19, an adjustment unit 60, and a control unit 70.

[0097] Figure 13 is a diagram illustrating the functional configuration of the water electrolysis apparatus according to the third embodiment. As shown in Figure 13, the water electrolysis apparatus 1 according to the third embodiment further includes: a first temperature sensor 81; and a second temperature sensor 82 for measuring the temperature distribution near the outlet of the flow path 211 in the electrolysis section 210 of the separators 25 and 26; other configurations are omitted. The second temperature sensor 82 includes second temperature sensors 82a, 82b, and 82c.

[0098] Figure 14 is a graph showing the relationship between the elapsed time after the start of electrolysis and the measured temperature. In Figure 14, the vertical axis represents the measured temperature (°C), and the horizontal axis represents the elapsed time (min) since the start of electrolysis. Figure 14 shows the temperature changes of the flow path outlet temperatures T1 and T2 among the flow path outlet temperatures T1, T2, and T3 of the electrolysis section 210 of separators 25 and 26. Graph G51a shows the temperature change of the flow path outlet temperature T1 after the start of electrolysis under normal conditions. Graph G51b shows the temperature change of the flow path outlet temperature T1 after the start of electrolysis when an abnormality of partial blockage of flow path 211 occurs. Graph G52a shows the temperature change of the flow path outlet temperature T2 after the start of electrolysis under normal conditions. Graph G52b shows the temperature change of the flow path outlet temperature T1 after the start of electrolysis when an abnormality of partial blockage of flow path 211 occurs. As shown in Figure 14, the temperature measured by the second temperature sensor 82 differs depending on whether the electrolysis section 210 of the separators 25 and 26 is operating normally or abnormally, depending on the temperature change since the start of electrolysis. Therefore, the water electrolysis apparatus 1 of the third embodiment can control the operation of water electrolysis by measuring the rate of change of the flow path outlet temperature of the electrolysis section 210 of the separators 25 and 26 over time.

[0099] As shown in Figure 13, the water electrolysis device 1 stores temperature change information 724 in the memory unit 72, which can identify the temperature changes of the flow path outlet temperatures T1, T2, and T3 from the start of electrolysis under normal conditions. The temperature change information 724 includes information that can identify the temperature changes of the flow path outlet temperatures T1, T2, and T3 from the start of electrolysis to the constant temperature. The temperature change information 724 may also include information that can identify temperature changes when the flow path outlet temperatures T1, T2, and T3 are abnormal.

[0100] (Regarding the control method for starting operation of the water electrolysis apparatus according to the third embodiment) Figure 15 is a flowchart illustrating an example of the processing sequence of the control method performed by the water electrolysis apparatus of the third embodiment at the start of electrolysis. The processing steps shown in Figure 15 are implemented by the control unit 70 of the water electrolysis apparatus 1 executing program 721.

[0101] As shown in Figure 15, the control unit 70 of the water electrolysis device 1 starts electrolysis operation (step S200). The control unit 70 opens the first water supply valve 42 and the second water supply valve 44, supplying electrolyte to the first electrolyte path 14 and the second electrolyte path 17 of the anode and cathode of the water electrolysis unit 11 through the first water supply path 41 and the second water supply path 43. At the same time, the control unit 70 starts the first circulation pump 31 and the second circulation pump 32 to make the electrolyte flow. The control unit 70 starts to supply power to the water electrolysis unit 11 to start the electrolysis reaction of the water electrolysis unit 11. Furthermore, the control unit 70 controls the flow rate of the electrolyte of the first circulation pump 31 and the second circulation pump 32 according to the current supplied to the water electrolysis unit 11. After step S200 is completed, the control unit 70 proceeds to step S201.

[0102] The control unit 70 continues to measure the flow path outlet temperatures T1, T2, and T3 in the electrolysis section 210 of separators 25 and 26 from the start of electrolysis (step S201). For example, the control unit 70 continues to acquire the flow path outlet temperatures T1, T2, and T3 measured by the second temperature sensor 82, and stores them as temperature information 722 in the memory unit 72 until a certain temperature is reached. The control unit 70 calculates the rate of temperature change per unit time until a certain temperature is reached, and associates it with the flow path outlet temperatures T1, T2, and T3 and sets it in the temperature information 722. After the processing in step S201 is completed, the control unit 70 proceeds to step S202.

[0103] The control unit 70 determines whether the temperature change per unit time is abnormal (step S202). For example, the control unit 70 compares the temperature changes over time for the flow path outlet temperatures T1, T2, and T3 displayed in the temperature information 722 with the temperature changes for the flow path outlet temperatures T1, T2, and T3 from the start of electrolysis to constant temperature displayed in the temperature change information 724. If there are inconsistent or dissimilar temperature changes, the control unit 70 determines that the temperature change per unit time is abnormal. When the control unit 70 determines that the temperature change per unit time is abnormal (step S202 is "yes"), the process proceeds to step S203.

[0104] The control unit 70 controls the flow rate of the electrolyte (step S203). For example, based on the current supplied to the water electrolysis unit 11, the control unit 70 controls the flow rate of the electrolyte in the first circulation pump 31 and the second circulation pump 32, and controls the flow rate of the electrolyte according to a predetermined response method. In this way, since the temperature change of the electrolysis unit 210 in the water electrolysis device 1 is abnormal, the abnormality of the electrolysis unit 210 can be eliminated by controlling the flow rate of the electrolyte. After the processing in step S203 is completed, the control unit 70 proceeds to step S208, which will be described later.

[0105] Furthermore, if the control unit 70 determines that the temperature change per unit time is not abnormal (step S202 is "No"), the process proceeds to step S204. The control unit 70 determines whether the temperature change of the flow path outlet temperature T1 is abnormal (step S204). For example, when the flow path outlet temperature T1 of the temperature information 722 reaches the constant temperature faster than usual, it indicates that multiple flow paths 211 in the electrolysis section 210 of the separators 25 and 26 may be completely blocked. Therefore, the control unit 70 determines that the temperature change of the flow path outlet temperature T1 is abnormal.

[0106] When the control unit 70 determines that the temperature change of the flow path outlet temperature T1 is abnormal (step S204 is "Yes"), it proceeds to step S205. The control unit 70 increases the electrolyte flow rate to a first flow rate (step S205). The first flow rate is a flow rate determined to eliminate the overall blockage of the multiple flow paths 211. For example, the control unit 70 controls the flow rate of the electrolyte in the first circulation pump 31 and the second circulation pump 32 to increase it according to the current supplied to the water electrolysis unit 11, thereby increasing the electrolyte flow rate to the first flow rate. In this way, since the temperature change of the flow path outlet temperature T1 of the water electrolysis device 1 is abnormal, the abnormality related to the flow path outlet temperature T1 can be eliminated by setting the electrolyte flow rate to the first flow rate. After the control unit 70 completes the processing in step S205, it proceeds to step S208, which will be described later.

[0107] Furthermore, when the control unit 70 determines that the temperature change of the flow path outlet temperature T1 is not abnormal (step S204 is "No"), it proceeds to step S206. The control unit 70 determines whether the flow path outlet temperature T2 reaches the constant temperature earlier than the flow path outlet temperature T1 (step S206). For example, when the flow path outlet temperature T2 of the temperature information 722 reaches the constant temperature earlier than the flow path outlet temperature T1 of the temperature information 722, the control unit 70 determines that the flow path outlet temperature T2 reaches the constant temperature earlier than the flow path outlet temperature T1. When the control unit 70 determines that the flow path outlet temperature T2 does not reach the constant temperature earlier than the flow path outlet temperature T1 (step S206 is "No"), since there is no abnormality in the multiple flow paths 211 in the electrolysis unit 210, it proceeds to step S208, which will be described later.

[0108] Furthermore, when the control unit 70 determines that the flow path outlet temperature T2 reaches the constant temperature earlier than the flow path outlet temperature T1 (step S206 is "Yes"), since multiple flow paths 211 in the electrolysis section 210 of separators 25 and 26 may be partially blocked, the process proceeds to step S207. The control unit 70 increases the electrolyte flow rate to a second flow rate (step S207). The second flow rate is a flow rate determined to eliminate the partial blockage of multiple flow paths 211. For example, the control unit 70 controls the flow rate of the electrolyte in the first circulation pump 31 and the second circulation pump 32 to increase it according to the current supplied to the water electrolysis unit 11, thereby increasing the electrolyte flow rate to the second flow rate. In this way, the water electrolysis device 1 can eliminate the partial blockage of flow paths 211 in the electrolysis section 210 by setting the electrolyte flow rate to the second flow rate. After the process in step S207 is completed, the control unit 70 proceeds to step S208.

[0109] The control unit 70 determines whether the process has ended (step S208). For example, the control unit 70 determines that the process has ended when the elapsed time after the start of electrolysis reaches a predetermined time. If the control unit 70 determines that the process has not ended (step S208 is "No"), it returns to the previously described step S201 to continue processing. Alternatively, if the control unit 70 determines that the process has ended (step S208 is "Yes"), it ends the processing steps shown in FIG15. After the processing steps shown in FIG15 are completed, the control unit 70 uses the control method described in the first embodiment to control the outlet temperature of the electrolysis section 210 of the pair of separators 25 and 26.

[0110] In this way, the water electrolysis apparatus 1 of the third embodiment measures the outlet temperature of the flow path at multiple different locations using the second temperature sensor 82, and controls the flow rate of the electrolyte flowing to the electrolysis section 210 based on the time change shown by the measurement results of the outlet temperature. Therefore, the water electrolysis apparatus 1 can determine the state of the electrolysis section 210 of the pair of separators 25 and 26 from the temperature change since the start of electrolysis, and thus change the flow rate of the electrolyte according to the state of the electrolysis section 210. As a result, the water electrolysis apparatus 1 can help eliminate abnormal states of the electrolysis section 210 of the pair of separators 25 and 26 at the start of electrolysis, and can suppress the deterioration of the state of the electrolysis section 210, thereby maintaining the performance of water electrolysis.

[0111] Regarding the water electrolysis apparatus 1 of the third embodiment, when the external ambient temperature is constant, it can also be configured to control the flow rate of the electrolyte flowing to the electrolysis section 210 based on the change in the external surface temperature of the water electrolysis unit 11 measured by the third temperature sensor 83 shown in the second embodiment. Furthermore, the water electrolysis apparatus 1 of the third embodiment can also be configured to further include a third temperature sensor 83, and control the flow rate of the electrolyte flowing to the electrolysis section 210 based on the temperature changes measured by the second temperature sensor 84 and the third temperature sensor 83.

[0112] The water electrolysis apparatus 1 of the first to third embodiments described above can be enhanced with the function of determining the state of the electrolysis section 210 of a pair of separators 25 and 26 based on the measured flow path outlet temperature, and notifying the determination result to an external device.

[0113] (Effect) The first-state water electrolysis apparatus 1 disclosed herein comprises: a water electrolysis stack 21 having a water electrolysis unit 11 with a solid polymer electrolyte membrane 22 disposed between a pair of separators 25 and 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for circulating electrolyte to the water electrolysis unit 11; and a first temperature sensor 81 capable of measuring the temperature of the electrolyte flowing at the inlet of the water electrolysis stack 21. The system includes: an inlet temperature of the electrolyte; a second temperature sensor 82, which measures the outlet temperature of the electrolyte flowing through the multiple flow paths 211 formed in the electrolysis section 210 of the separators 25 and 26; and a control unit 70, which adjusts at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the inlet temperature of the first temperature sensor 81 and the outlet temperature of the second temperature sensor 82, thereby reducing the temperature that has risen in a portion of the electrolysis section 210 of the separators 25 and 26. In this way, the water electrolysis device 1 can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature locally rises in the electrolysis section 210 of the pair of separators 25 and 26. As a result, the water electrolysis device 1 can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis.

[0114] In the second-state water electrolysis apparatus 1 disclosed herein, the control unit 70 adjusts at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis unit 210, such that the temperature of a portion of the electrolysis unit 210 in the separators 25 and 26 has been raised to below the heat resistance temperature of the solid polymer electrolyte membrane 22. In this way, the water electrolysis apparatus 1 can control the temperature of the electrolysis unit 210 below the heat resistance temperature of the solid polymer electrolyte membrane 22 when the temperature in the electrolysis unit 210 of the pair of separators 25 and 26 locally rises, thus reliably preventing damage to the solid polymer electrolyte membrane 22.

[0115] In the third-state water electrolysis apparatus 1 disclosed herein, the second temperature sensor 82 measures the outlet temperature of the aforementioned flow paths in the separators 25 and 26 at multiple different measurement positions along the width of the electrolysis section 210, which has multiple flow paths 211 arranged therein. Therefore, the water electrolysis apparatus 1 can determine the temperature distribution of the electrolysis section 210 from the outlet temperature of the flow paths measured by the second temperature sensor 82, and thus can appropriately adjust the temperature of the electrolyte, further contributing to the prevention of damage to the solid polymer electrolyte membrane 22.

[0116] The fourth-state water electrolysis apparatus 1 disclosed herein further includes: an adjustment unit 60, which adjusts the temperature of the electrolyte supplied to the inlet of the water electrolysis reactor 21; and a control unit 70, which, based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82, uses the adjustment unit 60 to lower the temperature of the electrolyte in the electrolysis section 210, thereby reducing the temperature that has been raised in a portion of the electrolysis section 210 in the separators 25 and 26. In this way, the water electrolysis apparatus 1 can provide an adjustment unit 60 at the inlet of the water electrolysis reactor 21, thus quickly lowering the temperature of the electrolyte in the electrolysis section 210, further contributing to the prevention of damage to the solid polymer electrolyte membrane 22.

[0117] In the fifth state of the water electrolysis apparatus 1 disclosed herein, the control unit 70 controls the flow rate of the electrolyte to the electrolysis unit 210 based on the temperature change measured by the second temperature sensor 82 from the start of electrolysis. In this way, the water electrolysis apparatus 1 can help eliminate abnormal conditions in the electrolysis unit 210 of the pair of separators 25 and 26 at the start of electrolysis, and can suppress the deterioration of the state of the electrolysis unit 210, thus maintaining the performance of water electrolysis.

[0118] In the water electrolysis apparatus 1 of the sixth state disclosed herein, when the control unit 70 detects a temperature change since the start of electrolysis as measured by the second temperature sensor 82, indicating a blockage in the electrolysis unit 210, it increases the flow rate of the electrolyte to the electrolysis unit 210. In this way, the water electrolysis apparatus 1 can quickly eliminate any abnormalities in the state of the electrolysis unit 210 of the pair of separators 25 and 26 at the start of electrolysis, thus maintaining the performance of water electrolysis.

[0119] The seventh-state water electrolysis device 1 disclosed herein comprises: a water electrolysis stack 21 having a water electrolysis unit 11 with a solid polymer electrolyte membrane 22 disposed between a pair of separators 25 and 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for circulating electrolyte to the water electrolysis unit 11; and a first temperature sensor 81 capable of measuring the temperature of the electrolyte flowing at the inlet of the water electrolysis stack 21. The device includes: an inlet temperature sensor 83, which measures the temperature of the outer surface of the water electrolysis stack 21 corresponding to the outlet of the plurality of flow paths 211 formed in the electrolysis section 210 of separators 25 and 26; and a control unit 70, which adjusts at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the outlet temperature of the plurality of flow paths 211 estimated from the inlet temperature and the temperature of the outer surface, so as to reduce the temperature that has risen in a part of the electrolysis section 210 of separators 25 and 26. In this way, the water electrolysis device 1 can prevent the solid polymer electrolyte membrane 22 from being damaged by temperature rise when the temperature rises locally in the electrolysis section 210 of a pair of separators 25 and 26. As a result, the water electrolysis device 1 can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis. Furthermore, since the water electrolysis device 1 only needs to measure the external surface temperature of the water electrolysis stack 21, it is not necessary to install the third temperature sensor 83 on the electrolysis section 210 of the separators 25 and 26, thereby simplifying the device structure.

[0120] In the water electrolysis device 1 of the eighth state disclosed herein, the water electrolysis stack 21 comprises multiple water electrolysis units 11 stacked in the stacking direction; the third temperature sensor 83 is disposed on the outer surface of the water electrolysis stack 21, including measurement positions at the center and ends in the stacking direction. Therefore, when the water electrolysis device 1 comprises multiple water electrolysis units 11 stacked, it is not necessary to provide a third temperature sensor 83 at each of the multiple water electrolysis units 11, thus suppressing the increase of the number of third temperature sensors 83 and thereby reducing the cost of the device.

[0121] The control method of the ninth state of the water electrolysis device 1 disclosed herein includes: a water electrolysis stack 21 having a water electrolysis unit 11 with a solid polymer electrolyte membrane 22 disposed between a pair of separators 25 and 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; and a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for cyclically supplying electrolyte to the water electrolysis unit 11; wherein the control method includes the following steps The control method includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack 21 using a first temperature sensor 81; measuring the outlet temperature of the electrolyte flowing at the outlet of the multiple flow paths 211 formed in the electrolysis section 210 of separators 25 and 26 using a second temperature sensor 82; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the inlet temperature and the outlet temperature, so as to reduce the temperature that has been raised in a portion of the electrolysis section 210 of separators 25 and 26. In this way, the control method can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature rises locally in the electrolysis section 210 of a pair of separators 25 and 26. As a result, the control method can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis.

[0122] The control method of the water electrolysis device 1 of the tenth state disclosed herein includes: a water electrolysis stack 21 having a water electrolysis unit 11 with a solid polymer electrolyte membrane 22 disposed between a pair of separators 25 and 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; and a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for cyclically supplying electrolyte to the water electrolysis unit 11; wherein the control method includes the following step: measuring the flow rate using a first temperature sensor 81. The steps include: measuring the inlet temperature of the electrolyte at the inlet of the water electrolysis reactor 21; measuring the temperature of the outer surface of the water electrolysis reactor 21 corresponding to the outlets of the plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25 and 26 using a third temperature sensor 83; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the flow path outlet temperatures estimated from the inlet temperature and the outer surface temperature, so as to reduce the temperature that has been raised in a portion of the electrolysis section 210 of the separators 25 and 26. In this way, the control method can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature locally rises in the electrolysis section 210 of a pair of separators 25 and 26. As a result, the control method can increase the temperature of the electrolyte, thereby improving the performance of water electrolysis. Furthermore, the control method only requires measuring the external surface temperature of the water electrolysis stack 21, so there is no need to install the third temperature sensor 83 on the electrolysis section 210 of the separators 25 and 26, thereby simplifying the device structure.

[0123] The 11th state of the program disclosed herein enables the water electrolysis device 1 to perform the following steps: The water electrolysis device comprises: a water electrolysis stack 21 having a water electrolysis unit 11 with a solid polymer electrolyte membrane 22 disposed between a pair of separators 25 and 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; and a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for cyclically supplying electrolyte to the water electrolysis unit 11; wherein the aforementioned steps include The process includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack 21 using a first temperature sensor 81; measuring the outlet temperature of the electrolyte flowing at the outlet of the multiple flow paths 211 formed in the electrolysis section 210 of separators 25 and 26 using a second temperature sensor 82; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the inlet temperature and the outlet temperature, so as to reduce the temperature that has risen in a portion of the electrolysis section 210 of separators 25 and 26. In this way, the program can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature in the electrolysis section 210 of a pair of separators 25 and 26 rises locally. As a result, the control method can increase the temperature of the electrolyte, thereby improving the water electrolysis performance of the water electrolysis device 1.

[0124] The program of the 12th state disclosed herein enables a water electrolysis device to perform the following steps: The water electrolysis device 1 comprises: a water electrolysis stack 21 having a water electrolysis unit 11 having a solid polymer electrolyte membrane 22 disposed between a pair of separators 25, 26, and using the water electrolysis unit 11 to electrolyze an electrolyte; a power supply unit 12 electrically connected to the water electrolysis stack 21; and a first electrolyte path 14 and a second electrolyte path 17 (electrolyte path) for circulatingly supplying electrolyte to the water electrolysis unit 11; wherein the aforementioned steps include: measuring the flow of electrolyte using a first temperature sensor 81. The process includes the following steps: measuring the inlet temperature of the electrolyte at the inlet of the water electrolysis reactor 21; measuring the temperature of the outer surface of the water electrolysis reactor 21 corresponding to the outlets of the plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25 and 26 using a third temperature sensor 83; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis section 210 based on the outlet temperatures of the plurality of flow paths 211 estimated from the inlet temperature and the outer surface temperature, so as to reduce the temperature that has been raised in a portion of the electrolysis section 210 of the separators 25 and 26. In this way, the program can prevent the solid polymer electrolyte membrane 22 from being damaged due to temperature rise when the temperature in the electrolysis section 210 of a pair of separators 25 and 26 rises locally. As a result, the program can increase the temperature of the electrolyte, thereby improving the water electrolysis performance of the water electrolysis device 1. Furthermore, the program only needs to measure the temperature of the outer surface of the water electrolysis stack 21 in the water electrolysis device 1, so there is no need to install the third temperature sensor 83 on the electrolysis section 210 of the separators 25 and 26, thereby simplifying the structure of the water electrolysis device 1.

[0125] The embodiments disclosed herein have been described above, but the content of these embodiments is not limited to the described embodiments. Furthermore, the aforementioned constituent elements include content readily conceived by those skilled in the art, substantially the same content, and content within the so-called equivalent scope. Moreover, the aforementioned constituent elements can be appropriately combined. Furthermore, various omissions, substitutions, or modifications can be made to the constituent elements without departing from the spirit of the aforementioned embodiments.

[0126] 1: Water electrolysis device 11: Water Electrolysis Unit 12: Power Supply Department 14: First electrolyte path 14a, 17a: Entry paths 14b, 17b: Export routes 15: First gas-liquid separation tank 15a, 18a: Filters 16: Oxygen Extraction Pathway 17: Second electrolyte path 18: Second gas-liquid separator 19: Hydrogen Extraction Pathway 20: End plate 21: Hydroelectric reactor 22: Solid polymer electrolyte membrane 23: Anode side 24: Cathode side 25, 26: Separator 27, 28: Power supply 29a: Inlet pipe section 29b: Export Control Department 31: First Circulation Pump 32: Second Circulation Pump 33: Hydrogen control valve 34: Auxiliary Path 35: Buffer tank 36: Water drain valve 41: First water supply route 42: First water supply valve 43: Second water supply route 44: Second water supply valve 51, 52: Catalyst layer 60: Adjustment Department 70: Control Department 72: Memory Department 81: First temperature sensor 82, 82a, 82b, 82c: Second temperature sensor 83: Third temperature sensor 200:Ontology 200A, 200B: Domain 201: Fixing part 210: Electrolysis Section 211:Flow path 220: Electrolyte inlet 230: Electrolyte outlet 240: Padding 721: Program 722: Temperature Information 723: Estimated Information 724: Temperature Change Information F: Longitudinal direction H: Stacking direction L: Direction L1, L2, L3: Flow direction P1, P2, P3, P4: Points T1, T2, T3: flow path outlet temperature W: Width direction

Claims

1. A water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path for circulatingly supplying the electrolyte to the water electrolysis unit; a first temperature sensor capable of measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack; a second temperature sensor capable of measuring the outlet temperature of the electrolyte flowing at the outlet of a plurality of flow paths formed in the electrolysis unit of the separators; and a control unit for controlling at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis unit based on the inlet temperature of the first temperature sensor and the outlet temperature of the second temperature sensor, such that the temperature of a portion of the electrolysis unit in the separators is reduced.

2. The water electrolysis apparatus as requested in item 1, wherein, The aforementioned control unit adjusts at least one of the flow rate, temperature, and current of the electrolyte in the aforementioned electrolysis unit, so that the temperature of a portion of the aforementioned electrolysis unit in the aforementioned separator has been raised to below the heat resistance temperature of the aforementioned solid polymer electrolyte membrane.

3. The water electrolysis apparatus as described in claim 2, wherein, The aforementioned second temperature sensor measures the outlet temperature of the aforementioned flow path in the aforementioned separator at multiple different measurement positions along the width of the aforementioned electrolysis section, which has multiple flow paths arranged in a row.

4. The water electrolysis apparatus as described in claim 3, wherein, It further includes: an adjustment unit for adjusting the temperature of the electrolyte supplied to the inlet of the aforementioned water electrolysis reactor; the aforementioned control unit uses the aforementioned adjustment unit to lower the temperature of the electrolyte in the aforementioned electrolysis unit based on the aforementioned inlet temperature of the aforementioned first temperature sensor and the aforementioned flow path outlet temperature of the aforementioned second temperature sensor, thereby reducing the temperature of a portion of the aforementioned electrolysis unit in the aforementioned separator that has been raised.

5. The water electrolysis apparatus as claimed in claim 1, wherein, The aforementioned control unit controls the flow rate of the electrolyte flowing to the aforementioned electrolysis unit based on the temperature change measured by the aforementioned second temperature sensor, which is calculated from the start of electrolysis.

6. The water electrolysis apparatus as claimed in claim 5, wherein, When the aforementioned control unit detects a temperature change since the start of electrolysis as measured by the aforementioned second temperature sensor, indicating that the aforementioned electrolysis unit is blocked, it increases the flow rate of the aforementioned electrolyte flowing into the aforementioned electrolysis unit.

7. A water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path for circulatingly supplying the electrolyte to the water electrolysis unit; a first temperature sensor capable of measuring the inlet temperature of the electrolyte flowing at the inlet of the water electrolysis stack; a third temperature sensor capable of measuring the temperature of the outer surface of the water electrolysis stack corresponding to the outlets of a plurality of flow paths formed in the electrolysis unit of the separator; and a control unit for adjusting at least one of the flow rate, temperature, and current of the electrolyte in the electrolysis unit based on the flow path outlet temperatures of the plurality of flow paths estimated from the inlet temperature and the temperature of the outer surface, thereby reducing the temperature that has been raised in a portion of the electrolysis unit of the separator.

8. The water electrolysis apparatus as claimed in claim 7, wherein, The aforementioned water electrolysis stack consists of multiple aforementioned water electrolysis units stacked in the stacking direction; the aforementioned third temperature sensor is disposed in the aforementioned outer surface of the aforementioned water electrolysis stack, including measurement positions at the center and ends in the aforementioned stacking direction.

9. A control method for a water electrolysis apparatus, the water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path for circulating the electrolyte to the water electrolysis unit; wherein... The control method includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the aforementioned water electrolysis reactor using a first temperature sensor; measuring the outlet temperature of the electrolyte flowing at the outlet of the plurality of flow paths formed in the electrolysis section of the aforementioned separator using a second temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the aforementioned electrolysis section based on the aforementioned inlet temperature and the aforementioned flow path outlet temperature, so as to reduce the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator.

10. A control method for a water electrolysis apparatus, the water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path for circulating the electrolyte to the water electrolysis unit; wherein... The control method includes the following steps: measuring the inlet temperature of the electrolyte flowing at the inlet of the aforementioned water electrolyzer using a first temperature sensor; measuring the temperature of the outer surface of the aforementioned water electrolyzer corresponding to the outlets of the plurality of flow paths formed in the electrolysis section of the aforementioned separator using a third temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the aforementioned electrolyte in the aforementioned electrolysis section based on the flow path outlet temperatures estimated from the aforementioned inlet temperature and the aforementioned outer surface temperature, so as to reduce the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator.

11. A water electrolysis process that causes a water electrolysis apparatus to perform the following steps, the water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path that circulates the electrolyte to the water electrolysis unit; wherein... The aforementioned steps include: measuring the inlet temperature of the electrolyte flowing at the inlet of the aforementioned water electrolysis reactor using a first temperature sensor; measuring the outlet temperature of the electrolyte flowing at the outlet of the plurality of flow paths formed in the electrolysis section of the aforementioned separator using a second temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte in the aforementioned electrolysis section based on the aforementioned inlet temperature and the aforementioned flow path outlet temperature, so as to reduce the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator.

12. A water electrolysis process that causes a water electrolysis apparatus to perform the following steps, the water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis unit having a solid polymer electrolyte membrane disposed between a pair of separators, and using the water electrolysis unit to electrolyze an electrolyte; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path that circulates the electrolyte to the water electrolysis unit; wherein... The aforementioned steps include: measuring the inlet temperature of the electrolyte flowing at the inlet of the aforementioned water electrolyzer using a first temperature sensor; measuring the temperature of the outer surface of the aforementioned water electrolyzer corresponding to the outlets of the plurality of flow paths formed in the electrolysis section of the aforementioned separator using a third temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the aforementioned electrolyte in the aforementioned electrolysis section based on the flow path outlet temperatures of the plurality of flow paths estimated from the aforementioned inlet temperature and the aforementioned outer surface temperature, so as to reduce the temperature that has been raised in a portion of the aforementioned electrolysis section of the aforementioned separator.

Images