Water electrolysis apparatus, control method, and program

Abstract

This prevents damage to the electrolyte membrane even if the electrolyte temperature rises. [Solution] The water electrolysis apparatus 1 includes a water electrolysis stack that electrolyzes an electrolyte using a water electrolysis cell having a solid polymer electrolyte membrane arranged between a pair of separators 25, 26, a power supply unit electrically connected to the water electrolysis stack, an electrolyte path that circulates and supplies electrolyte to the water electrolysis cell, a first temperature sensor 81 capable of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack, a second temperature sensor 82 capable of measuring the flow path outlet temperature of the electrolyte flowing through the outlets of a plurality of flow paths formed in the electrolysis section 210 of the separators 25, 26, and a control unit 70 that performs control to adjust at least one of the flow rate, temperature, and current amount of the electrolyte to the electrolysis section 210 in order to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26, based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82.

Description

[Technical Field]

[0001] This disclosure relates to a water electrolysis apparatus, a control method, and a program. [Background technology]

[0002] A water electrolysis apparatus produces oxygen and hydrogen by electrolyzing water in a water electrolysis cell. Patent Document 1 discloses a water electrolysis system that measures the temperature of a water electrolysis stack or the temperature of water discharged from a water electrolysis stack and adjusts the temperature of the water supplied to multiple water electrolysis stacks using a cooler. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2023 / 012944 [Overview of the project] [Problems that the invention aims to solve]

[0004] To improve the electrolysis performance of a water electrolysis device, it is necessary to raise the temperature of the electrolyte circulating through the water electrolysis cell. However, the temperature of the electrolyte must be kept below the heat resistance temperature of the electrolyte membrane, such as the anion exchange membrane used in the water electrolysis cell.

[0005] This disclosure aims to solve the aforementioned problems and to provide a water electrolysis apparatus, control method, and program that can prevent damage to the electrolyte membrane even when the temperature of the electrolyte is increased. [Means for solving the problem]

[0006] The water electrolysis apparatus according to this disclosure comprises a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, which electrolyzes an electrolyte solution using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path for circulating and supplying the electrolyte solution to the water electrolysis cell; a first temperature sensor capable of measuring the inlet temperature of the electrolyte solution flowing through the inlet of the water electrolysis stack; a second temperature sensor capable of measuring the flow path outlet temperature of the electrolyte solution flowing through the outlets of a plurality of flow paths formed in the electrolysis section of the separator; and a control unit that performs control to adjust at least one of the flow rate, temperature, and current amount of the electrolyte solution to the electrolysis section in order to reduce the temperature that has risen in a part of the electrolysis section of the separator, based on the inlet temperature of the first temperature sensor and the flow path outlet temperature of the second temperature sensor.

[0007] The water electrolysis apparatus according to this disclosure comprises a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, which electrolyzes an electrolyte solution using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; an electrolyte path for circulating and supplying the electrolyte solution to the water electrolysis cell; a first temperature sensor capable of measuring the inlet temperature of the electrolyte solution flowing through 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 section of the separator; and a control unit that performs control to adjust at least one of the flow rate, temperature, and current amount of the electrolyte solution to the electrolysis section in order to reduce the temperature that has risen in a part of the electrolysis section of the separator, based on the flow rate outlet temperature of the flow path flowing through the outlets of the plurality of flow paths estimated from the inlet temperature and the temperature of the outer surface.

[0008] The control method according to the present disclosure is a control method for a water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, and which electrolyzes an electrolyte using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, the method comprising: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; measuring the flow path outlet temperature of the electrolyte flowing through the outlets of a plurality of flow paths formed in the electrolysis section of the separator with a second temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolysis section based on the inlet temperature and the flow path outlet temperature, so as to reduce the temperature that has risen in a part of the electrolysis section of the separator.

[0009] The control method according to the present disclosure is a control method for a water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, and which electrolyzes an electrolyte using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, the method comprising: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with 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 with a third temperature sensor; and adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolysis section so as to reduce the temperature that has risen in a part of the electrolysis section of the separator, 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.

[0010] The program according to this disclosure causes a water electrolysis apparatus to perform the following steps: measure the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; measure the flow path outlet temperature of the electrolyte flowing through the outlet of a plurality of flow paths formed in the electrolytic section of the separator with a second temperature sensor; and adjust at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section so as to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the inlet temperature and the flow path outlet temperature.

[0011] The program according to this disclosure causes a water electrolysis apparatus to perform the following steps: measure the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; measure the temperature of the outer surface of the water electrolysis stack corresponding to the outlet of a plurality of flow channels formed in the electrolytic section of the separator with a third temperature sensor; and adjust at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section so as to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the flow rate outlet temperature of the outlet of the plurality of flow channels estimated from the inlet temperature and the temperature of the outer surface of the separator. [Effects of the Invention]

[0012] According to this disclosure, damage to the electrolyte membrane can be prevented even if the temperature of the electrolyte rises. [Brief explanation of the drawing]

[0013] [Figure 1]FIG. 1 is a schematic diagram showing a schematic configuration of a water electrolysis apparatus according to the first embodiment. [Figure 2] FIG. 2 is an exploded view showing a configuration example of a water electrolysis cell. [Figure 3] FIG. 3 is a diagram showing a configuration example of a separator. [Figure 4] FIG. 4 is a graph showing the relationship between the temperature difference between the flow path and the cell inlet when the current density of the electrolysis test conditions is 1 A / cm2. [Figure 5] FIG. 5 is a graph showing the relationship between the temperature difference between the flow path and the cell inlet when the current density of the electrolysis test conditions is 3 A / cm2. [Figure 6] FIG. 6 is a partial perspective schematic diagram for explaining an arrangement example of temperature sensors of a water electrolysis apparatus. [Figure 7] FIG. 7 is a diagram for explaining a functional configuration of a water electrolysis apparatus according to the first embodiment. [Figure 8] [[ID=2A]]FIG. 8 is a flowchart showing an example of a processing procedure of a control method executed by the water electrolysis apparatus according to the first embodiment. [[ID=2B]] [Figure 9] FIG. 9 is a diagram for explaining a functional configuration of a water electrolysis apparatus according to the second embodiment. [[ID=Z5]] [Figure 10] FIG. 10 is a graph showing the temperatures of the inside and the outer surface of a water electrolysis stack. [Figure 11] FIG. 11 is a schematic diagram showing an example of a water electrolysis stack in which a plurality of water electrolysis cells are stacked. [Figure 12] FIG. 12 is a flowchart showing an example of a processing procedure of a control method executed by the water electrolysis apparatus according to the second embodiment. [Figure 13] FIG. 13 is a diagram for explaining a functional configuration of a water electrolysis apparatus according to the third embodiment. [Figure 14] FIG. 14 is a graph showing the relationship between the elapsed time after the start of electrolysis and the measured temperature. [Figure 15] FIG. 15 is a flowchart showing an example of a processing procedure of a control method at the start of electrolysis executed by the water electrolysis apparatus according to the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0014] Preferred embodiments of the present disclosure will be described in detail below with reference to the attached drawings. However, this disclosure is not limited to these embodiments, and if there are multiple embodiments, they may be combinations of these embodiments.

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

[0016] The water electrolysis cell 11 is configured such that an anode is placed on one side of a hydrogen ion-permeable solid polymer electrolyte membrane 22 and a cathode is placed on the other side within a water electrolysis stack 21. The solid polymer electrolyte membrane 22 can be, for example, an ion exchange membrane such as an anion exchange membrane. The water electrolysis cell 11 is configured within the water electrolysis stack 21 by stacking one or more of these membranes. The water electrolysis cell 11 generates oxygen gas on the anode side 23 and hydrogen gas on the cathode side 24 by electrolyzing the electrolyte solution using the solid polymer electrolyte membrane 22.

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

[0018] The control unit 70 receives power from the power supply unit 12 and controls the current and voltage values ​​of the power supplied to the anode and cathode, which are arranged on both sides of the solid polymer electrolyte membrane 22 of the water electrolysis cell 11. By doing so, it supplies power to the water electrolysis cell 11 to perform water electrolysis and generate oxygen gas and hydrogen gas.

[0019] The first electrolyte path 14 circulates the electrolyte to the water electrolysis stack 21 and supplies the electrolyte to the anode side 23 of the water electrolysis cell 11, thereby enabling the electrolysis of the electrolyte (water). The first electrolyte path 14 is connected to the first gas-liquid separation tank 15. The first electrolyte path 14 has an inlet path 14a to the water electrolysis stack 21 and an outlet path 14b from the water electrolysis stack 21. The inlet path 14a of the first electrolyte path 14 is provided with a first circulation pump 31. In this embodiment, the first electrolyte path is composed of the first electrolyte path 14 and the first gas-liquid separation tank 15.

[0020] The first gas-liquid separation tank 15 separates and extracts oxygen gas present as bubbles or dissolved in the circulating electrolyte (water), and an oxygen gas extraction path 16 for discharging the separated oxygen gas is connected to its upper part. The first gas-liquid separation tank 15 has a built-in filter 15a, which removes impurities (such as leached metals) generated by the electrolysis of water, and then supplies the water back to the water electrolysis stack 21.

[0021] The second electrolyte path 17 circulates the electrolyte to the water electrolysis stack 21 and supplies the electrolyte to the cathode side 24 of the water electrolysis cell 11, thereby enabling cooling of the solid polymer electrolyte membrane 22 and discharge of hydrogen gas. The second electrolyte path 17 is connected to the second gas-liquid separation tank 18. The second electrolyte path 17 has an inlet path 17a to the water electrolysis stack 21 and an outlet path 17b from the water electrolysis stack 21. The inlet path 17a of the second electrolyte path 17 is provided with a second circulation pump 32. In this embodiment, the second electrolyte path is composed of the second electrolyte path 17 and the second gas-liquid separation tank 18.

[0022] The second gas-liquid separation tank 18 separates and extracts hydrogen gas present as bubbles or dissolved in the circulating electrolyte (water), and a hydrogen gas extraction path 19 for discharging the separated hydrogen gas is connected to its upper part. The second gas-liquid separation tank 18 is equipped with a hydrogen control valve 33 in the hydrogen gas extraction path 19. The second gas-liquid separation tank 18 has a built-in filter 18a, which removes impurities generated by the electrolysis of water before supplying it back to the water electrolysis stack 21.

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

[0024] The first water supply path 41 can supply electrolyte to the first gas-liquid separation tank 15 from the outside, thereby boosting and controlling the pressure in the first electrolyte path 14 and the first gas-liquid separation tank 15 on the anode side 23 of the water electrolysis stack 21. The first water supply path 41 is equipped with a first water supply valve 42 for adjusting the amount of water supplied to the first gas-liquid separation tank 15. The first water supply path 41 is also equipped with a water supply pump (not shown). The electrolyte supplied from the first water supply path 41 is a solution of pure water with ionic substances dissolved in it, but an electrolyte with pre-dissolved oxygen gas may also be introduced.

[0025] The second water supply path 43 can supply water to the second gas-liquid separation tank 18 from the outside, thereby boosting and controlling the pressure in the second electrolyte path 17 and the second gas-liquid separation tank 18 on the cathode side 24 of the water electrolysis stack 21. The second water supply path 43 is equipped with a second water supply valve 44 for adjusting the amount of water supplied to the second gas-liquid separation tank 18. A water supply pump (not shown) is also provided in the second water supply path 43. Although pure water is used for the water supplied from the second water supply path 43, an electrolyte solution with pre-dissolved hydrogen gas may also be introduced.

[0026] The adjustment unit 60 is provided near the electrolyte inlet on the anode side 23 and cathode side 24 of the water electrolysis cell 11, and is configured to adjust the temperature of the electrolyte supplied to the water electrolysis cell 11. The adjustment unit 60 includes, for example, an air-cooled or water-cooled chiller that can adjust the temperature of the electrolyte. 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 can maintain the electrolyte at a constant temperature by adjusting the rise or fall of the temperature of the electrolyte supplied to the water electrolysis cell 11 under the control of the control unit 70.

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

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

[0029] When the operator activates the start switch for 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 cell 11 via the first water supply path 41 and the second water supply path 43. At the same time, the control unit 70 operates the first circulation pump 31 and the second circulation pump 32 to circulate the electrolyte. The control unit 70 then starts supplying power to the water electrolysis cell 11 to begin the electrolytic reaction in the water electrolysis cell 11. At this time, the control unit 70 seals the second electrolyte path 17 by closing the hydrogen gas extraction path 19 with the hydrogen control valve 33. The control unit 70 controls the flow rate of the electrolyte by the first circulation pump 31 and the second circulation pump 32 according to the current supplied to the water electrolysis cell 11.

[0030] The control unit 70 controls the current and voltage values ​​to the anode and cathode arranged on both sides of the solid polymer electrolyte membrane 22, thereby electrolyzing the electrolyte on the anode side 23 by the anode and cathode arranged on both sides of the solid polymer electrolyte membrane 22. That is, when the electrolyte is supplied to the anode and cathode arranged on both sides of the solid polymer electrolyte membrane 22 on the anode side 23 of the water electrolysis cell 11, a reaction occurs on the cathode side 24 of the solid polymer electrolyte membrane 22, producing hydrogen gas and hydroxide ions (OH). - This generates hydroxide ions (OH). - The reaction between the anode side 23 and the cathode side 24 involves the formation of water due to the potential difference between them. The water then moves from the cathode side 24 through the solid polymer electrolyte membrane 22 to the anode side 23, where it reacts to generate oxygen gas.

[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 closes the first electrolyte path 14 and the second electrolyte path 17 when a predetermined electrolyte pressure is reached. 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, since the electrolyte pressure in the second electrolyte path 17 of the water electrolysis device 1 is higher than the steady-state pressure, hydrogen gas dissolves easily into the electrolyte. Therefore, in the water electrolysis device 1, the hydrogen gas generated on the cathode side 24 circulates through the second electrolyte path 17 while dissolved in the electrolyte.

[0032] In the water electrolysis device 1, as the generated hydrogen gas dissolves into the electrolyte and the amount of dissolved hydrogen increases, the amount of dissolved hydrogen reaches a saturation point after a predetermined time, at which point no more hydrogen gas can be dissolved in the water. Therefore, when the amount of dissolved hydrogen in the electrolyte of the second electrolyte path 17 exceeds the saturation point, the control unit 70 opens the hydrogen control valve 33. As a result, the pressure in the hydrogen gas extraction path 19 of the water electrolysis device 1 increases, and the amount of hydrogen acquired increases. Then, when the amount of hydrogen acquired exceeds a predetermined 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 acquire a predetermined amount of hydrogen at a predetermined pressure.

[0033] (Configuration of a water electrolysis cell) Figure 2 is an exploded view showing an example of the configuration of a water electrolysis cell. Figure 3 is a diagram showing an example of the configuration of a separator. In the example shown in Figure 2, a single water electrolysis cell 11 is shown for the sake of simplicity, but a configuration in which multiple cells are stacked may also be used.

[0034] As shown in Figure 2, the water electrolysis cell 11 includes a pair of separators 25 and 26, a solid polymer electrolyte membrane 22 provided between the pair of separators 25 and 26, and power supply units 27 and 28 provided between the solid polymer electrolyte membrane 22 and the pair of separators 25 and 26. The water electrolysis cell 11 further includes a catalyst layer 51 interposed between the power supply unit 27 on the anode side 23 and the solid polymer electrolyte membrane 22, and a catalyst layer 52 interposed 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 cell 11 has a multilayer stack structure in which the separator 25, power supply 27, catalyst layer 51, solid polymer electrolyte membrane 22, catalyst layer 52, power supply 28, and separator 25 are stacked in that order from the anode side 23 toward the cathode side 24.

[0035] The pair of separators 25 and 26 are formed in the shape of rectangular plates from a metal material that does not allow oxygen and hydrogen generated by water electrolysis to pass through. The pair of separators 25 and 26 have an inlet tube section 29a, which is the entrance to the electrolyte, and an outlet tube section 29b, which is the exit for the electrolyte. The pair of inlet tube sections 29a communicate with the inlet path 14a of the first electrolyte path 14 and the inlet path 17a of the second electrolyte path 17, respectively. The pair of outlet tube sections 29b communicate with the outlet path 14b of the first electrolyte path 14 and the outlet path 17b of the second electrolyte path 17, respectively.

[0036] As shown in Figure 3, the pair of separators 25 and 26 each have a main body 200, an electrolytic section 210 formed in the center of the main body 200, an electrolyte inlet 220 provided on one side of the electrolytic section 210, and an electrolyte outlet 230 provided on the other side of the electrolytic section 210. The pair of separators 25 and 26 have the electrolyte inlet 220 and the electrolyte outlet 230 arranged diagonally on the main body 200, with the electrolytic section 210 provided between them. The main body 200 has two opposing fixing sections 201 formed thereon, and is fixed in the stacking position by fixing members passing through the fixing sections 201.

[0037] The electrolytic section 210 is a portion of the plane of the main body 200 and is the region where the power supply units 27 and 28 are stacked (in contact). The electrolytic section 210 has multiple flow channels 211 for flowing the electrolyte (pure water) to be electrolyzed outside the power supply units 27 and 28. The multiple flow channels 211 are arranged at equal intervals along the width direction W of the separators 25 and 26 and are formed as multiple grooves extending along the longitudinal direction F. The multiple flow channels 211 are the parts of the electrolytic section 210 through which the electrolyte and gas flow. The longitudinal direction F is the direction in which the electrolyte flows in the electrolytic section 210 and is perpendicular to the width direction W. The flow velocity of the electrolyte is faster in the multiple flow channels 211 closer to the electrolyte inlet 220 and slower as it moves away from the inlet.

[0038] The electrolyte inlet 220 is a hole formed near one corner of the electrolytic unit 210 in one region 200A of the main body 200 that surrounds the electrolytic unit 210, and communicates with the inlet tube portion 29a of separator 25 or separator 26. The electrolyte inlet 220 supplies the electrolyte from the inlet tube portion 29a to the entirety of the multiple flow paths 211 of the electrolytic unit 210.

[0039] The electrolyte outlet 230 is a hole formed in the region 200B on the other side of the region surrounding the electrolytic section 210 of the main body 200, near the other corner of the electrolytic section 210, and facing the electrolyte inlet 220. It 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 electrolytic section 210 and merged into the outlet pipe 29b.

[0040] The pair of separators 25 and 26 surround the electrolytic unit 210, the electrolyte inlet 220, and the electrolyte outlet 230 with packing 240, thereby restricting the area through which the electrolyte flows. As a result, the pair of separators 25 and 26 improve the efficiency of supplying electrolyte from the electrolyte inlet 220 to the electrolytic unit 210, and the efficiency of discharging electrolyte from the electrolytic unit 210 to the electrolyte outlet 230, using packing 240.

[0041] The pair of separators 25 and 26 receive the electrolyte from the electrolyte inlet 220, which then flows in directions such as L1, L2, L3, and so on, splitting into multiple flow channels 211 in the electrolytic unit 210. The electrolyte then flows through each of the multiple flow channels 211, and after passing through the outlets of the multiple flow channels 211, the electrolyte rejoins and flows into the electrolyte outlet 230. The electrolyte flowing in flow direction L1 flows faster than the electrolyte flowing in flow direction L2. The electrolyte flowing in flow direction L2 flows faster than the electrolyte flowing in flow direction L3.

[0042] The power supply units 27 and 28 are made of metal mesh and are formed to be stackable with the electrolytic section 210 and catalyst layers 51 and 52 of the separators 25 and 26. The power supply units 27 and 28 are configured to receive power from the power supply unit 12 via end plates located on the outside of the water electrolysis cell 11.

[0043] (Water electrolysis reaction of the water electrolysis cell) As shown in Fig. 2, in the water electrolysis cell 11, an electrolytic solution (H2O) is supplied to the separator 25 on the anode side 23 and the separator 26 on the cathode side 24, and a voltage is applied to the power supply body 27 and the power supply body 28. In the water electrolysis cell 11, on the cathode side 24, as in the cathode reaction shown in the following (Equation 1), the electrolytic solution (H2O) flowing through the plurality of flow paths 211 of the separator 26 reacts in the catalyst layer 52, and a reduction reaction of water occurs, generating hydrogen (H2) and hydroxide ions (OH - ), and the hydroxide ions (OH - ) move through the solid polymer electrolyte membrane 22 toward the anode side 23. 2H2O + 2e - → H2 + 2OH - ···(Equation 1)

[0044] Then, in the water electrolysis cell 11, on the anode side 23, as in the anode reaction shown in the following (Equation 2), oxygen (O2) and water (H2O) are generated in the catalyst layer 51 from the hydroxide ions (OH - ) that have moved through the solid polymer electrolyte membrane 22. 2OH - → 1 / 2O2 + H2O + 2e - ···(Equation 2)

[0045] From (Equation 1) and (Equation 2), the overall reaction generates oxygen and hydrogen from water, as shown in the following (Equation 3). H2O → H2 + 1 / 2O2 ···(Equation 3)

[0046] In the water electrolysis cell 11, the separator 25 on the anode side 23 discharges the electrolytic solution (O2 + H2O) containing oxygen from the outlet pipe portion 29b, and the separator 26 on the cathode side discharges the electrolytic solution (H2 + H2O) containing hydrogen from the outlet pipe portion 29b.

[0047] In order to improve the performance of the water electrolysis cell 11, the water electrolysis device 1 needs to raise the temperature of the electrolyte. However, if the solid polymer electrolyte membrane 22 is an anion exchange membrane, it is necessary to keep the temperature below the heat resistance temperature. In this embodiment, the water electrolysis device 1 realizes a technology that suppresses the rise in temperature of the solid polymer electrolyte membrane 22 and improves the performance of the water electrolysis cell 11.

[0048] (Separator flow path) Next, we will explain the test results of electrolysis tests conducted using model separators 25 and 26 that utilize the water electrolysis cell 11. The model separators differ from the actual separators 25 and 26 in terms of the width and number of flow channels 211 (grooves).

[0049] Figure 4 shows the current density under the electrolysis test conditions of 1 A / cm². 2 This graph shows the relationship between the flow path and the temperature difference at the cell inlet in this case. Figure 5 shows the current density under electrolysis test conditions of 3 A / cm². 2 This graph shows the relationship between the flow path and the temperature difference at the cell inlet in this case. Note that current density is the amount of electricity (charge) flowing per unit time in a direction perpendicular to a unit area in the power supply 27 and power supply 28.

[0050] Figures 4 and 5 show the results of measuring the outlet temperatures of multiple flow channels 211 in the separator 26 on the cathode side 24 of the water electrolysis cell 11 using a temperature sensor. The flow channel outlet temperature is the temperature measured near the outlet of the flow channel 211 through which the electrolyte flows. In Figures 4 and 5, the vertical axis shows the temperature difference (°C) between the inlet temperature of the separator 26 and the outlet temperatures of the multiple flow channels 211. In Figures 4 and 5, the horizontal axis shows the flow channel numbers assigned to the multiple flow channels 211 in the width direction W of the electrolysis unit 210, moving from one side near the electrolyte inlet 220 to the other side further away. 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 channel 211 shown in Figure 3.

[0051] Graphs G11 and G13 in Figure 4 show the current density under electrolysis test conditions of 1 A / cm². 2The graph shows the temperature difference between the inlet temperature of the separator 26 and the flow path outlet temperature measured at four measurement points near the outlet of the flow path 211, when the electrolyte flow rate to the water electrolysis cell 11 is changed to 0.8 kg / (min·cell) and 1.5 kg / (min·cell). In other words, the electrolyte flow rate decreases in the order of graph G13 and G11. The measurement results shown in Figure 4 indicate that the effect of heat dissipation in the electrolysis section 210 of the separator 26 is large, and the temperature difference on the outside in the width direction W is large. The measurement results shown in Figure 4 show that the flow path outlet temperatures of multiple flow paths 211 are lower than the inlet temperature of the separator 26, and the temperature difference is negative.

[0052] Graphs G31 and G32 in Figure 5 show the current density under electrolysis test conditions of 3 A / cm². 2 The graph shows 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 near the outlet of the flow path 211, when the electrolyte flow rate to the water electrolysis cell 11 is changed to 1.5 kg / (min·cell) and 3.0 kg / (min·cell). In other words, the electrolyte flow rate decreases in the order of graphs G32 and G31. The measurement results shown in Figure 5 show that the maximum temperature difference in the width direction W of the electrolysis section 210 of the separator 26 is 13°C, and the temperature difference increases as the electrolyte flow rate decreases.

[0053] Thus, the results of the electrolysis test showed that as the current density of the water electrolysis cell 11 increases, the temperature distribution (temperature difference) in the width direction W of the separator 26 tends to increase. In other words, it was found that the electrolysis section 210 of the separators 25 and 26 has a temperature distribution, and this temperature distribution changes according to the current density. For example, if the separator temperature rises locally in the electrolysis section 210 of the separators 25 and 26, it may not be possible to detect the abnormality by measuring only the electrolyte temperature at the stack outlet of the water electrolysis stack 21. As a result, the water electrolysis device 1 according to this embodiment suppresses the rise in temperature of the solid polymer electrolyte membrane 22, improves the performance of the water electrolysis cell 11, and prevents damage to the solid polymer electrolyte membrane 22. In detail, the water electrolysis device 1 measures the temperature of the electrolyte near the outlet of the flow path 211 of the water electrolysis cell 11 at multiple locations, and prevents damage to the solid polymer electrolyte membrane 22 by controlling the temperature of the electrolyte when the temperature rises locally.

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

[0055] In the example shown in Figure 6, the water electrolysis cell 11 is sandwiched on both sides by end plates 20, with an inlet path 14a and an outlet path 14b connected to the anode side end plate 20 23, and an inlet path 17a and an outlet path 17b connected to the cathode side end plate 20 24. In this embodiment, if the solid polymer electrolyte membrane 22 of the water electrolysis cell 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 cell 11 is 75.5°C or lower.

[0056] The water electrolysis apparatus 1 further includes a first temperature sensor 81 that measures the inlet temperature of the electrolyte flowing into the inlet of the water electrolysis stack 21, and a second temperature sensor 82 that measures the outlet temperature of the electrolyte flowing through the outlets of a plurality of flow channels 211 formed in the electrolysis section 210 of the separators 25 and 26. The first temperature sensor 81 is provided in the inlet paths 14a and 17a of the water electrolysis cell 11 to the water electrolysis stack 21, and is electrically connected to the control unit 70. The second temperature sensor 82 is provided at the outlet of the flow channels 211 of the separators 25 and 26 of the water electrolysis cell 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, a thermistor, a resistance thermometer, a thermocouple, etc. The first temperature sensor 81 and the second temperature sensor 82 supply temperature information that can identify the measured electrolyte temperature to the control unit 70.

[0057] In the example shown in Figure 7, the water electrolysis apparatus 1 is configured to include a control unit 70, a first temperature sensor 81, and a second temperature sensor 82, with other components omitted.

[0058] The second temperature sensor 82 comprises a second temperature sensor 82a, a second temperature sensor 82b, and a second temperature sensor 82c. The second temperature sensor 82a measures the flow outlet temperature in the flow direction L1 of the electrolytic section 210 of the separators 25 and 26. The second temperature sensor 82b measures the flow outlet temperature in the flow direction L2 of the electrolytic section 210 of the separators 25 and 26. The second temperature sensor 82c measures the flow outlet temperature in the flow direction L3 of the electrolytic section 210 of the separators 25 and 26. In the following description, if it is not necessary to distinguish between the second temperature sensor 82a, the second temperature sensor 82b, and the second temperature sensor 82c, they will simply be referred to as the second temperature sensor 82.

[0059] The control unit 70 is an arithmetic unit, or CPU (Central Processing Unit). The control unit 70 reads and executes programs (software) from the storage unit 72 to realize various functions and perform the processing. The control unit 70 may perform processing with a single CPU, or it may have multiple CPUs and perform processing with those multiple CPUs. In this embodiment, the control unit 70 is electrically connected to the storage unit 72, but the storage unit 72 may be built into the control unit 70.

[0060] The storage unit 72 is a memory that stores various information such as the calculation contents and programs of the control unit 70, and includes at least one of the following: RAM, main memory such as ROM, and external memory such as HDD. The storage unit 72 can store programs 721, temperature information 722, etc. Program 721 includes a program for realizing control related to water electrolysis of the water electrolysis apparatus 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 a plurality of 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 storage unit 72 stores the plurality of temperature information 722 in chronological order. The time-series temperature information 722 allows for the identification of changes in the temperature distribution in the electrolytic section 210 of the separators 25 and 26, high-temperature regions, etc., based on the flow path outlet temperatures of multiple second temperature sensors 82.

[0061] The control unit 70 adjusts the temperature of the electrolytic section 210 of the separators 25 and 26 to reduce the temperature rise of the electrolytic section 210 of the 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. The control unit 70 estimates the temperature distribution of the electrolytic section 210 of the 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 electrolytic section 210 where the temperature is locally rising. The control unit 70 controls the temperature of the electrolyte so that the temperature of the electrolytic section 210 of the separators 25 and 26 is below the heat resistance temperature of the solid polymer electrolyte membrane 22. The control unit 70 controls the adjustment unit 60 so that the temperature of the electrolytic section 210 of the separators 25 and 26 is below the heat resistance temperature of the solid polymer electrolyte membrane 22, based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82.

[0062] (Control method for a water electrolysis apparatus according to the first embodiment) Figure 8 is a flowchart showing an example of a processing procedure of the control method executed by the water electrolysis apparatus according to the first embodiment. The processing procedure shown in Figure 8 is realized when the control unit 70 of the water electrolysis apparatus 1 executes the 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 the separators 25 and 26 (step S101). For example, the control unit 70 acquires the flow path outlet temperatures T1, T2, and T3 measured by the second temperature sensor 82 and stores them in the storage unit 72 as temperature information 722. When the processing in step S101 is completed, the control unit 70 proceeds to step S102.

[0064] The control unit 70 determines whether the flow channel outlet temperatures T1, T2, and T3 are equal to or greater than the first heat resistance temperature (step S102). For example, if the first heat resistance temperature of the solid polymer electrolyte membrane 22 is 80°C, the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are equal to or greater than the first heat resistance temperature if all of the flow channel outlet temperatures T1, T2, and T3 are 80°C or greater. If the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are equal to or greater than the first heat resistance temperature (Yes in step S102), it proceeds to step S103.

[0065] The control unit 70 reduces the current or stops the electrolysis operation (step S103). For example, the control unit 70 reduces the current (current density) because the flow path outlet temperatures T1, T2, and T3 are above the first heat resistance temperature. Alternatively, the control unit 70 stops the electrolysis operation in the water electrolysis apparatus 1. As a result, the water electrolysis apparatus 1 reduces the temperature of the electrolysis section 210 by reducing the current or stopping the electrolysis operation because the temperature of the electrolysis section 210 is above the first heat resistance temperature overall. When the process in step S103 is completed, the control unit 70 proceeds to step S110, which will be described later.

[0066] Furthermore, if the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are not above the first heat resistance temperature (No in step S102), it proceeds to step S104. The control unit 70 determines whether the flow channel outlet temperatures T1, T2, and T3 are above the second heat resistance temperature (step S104). For example, if the second heat resistance temperature of the solid polymer electrolyte membrane 22 is 75°C, which is lower than the first heat resistance temperature, the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are above the second heat resistance temperature if all of them are 75°C or higher. If the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are not above the second heat resistance temperature (No in step S104), it determines that the flow channel outlet temperatures T1, T2, and T3 are normal, and proceeds to step S110, which will be described later. Furthermore, if the control unit 70 determines that the flow path outlet temperatures T1, T2, and T3 are equal to or greater than the second heat resistance temperature (Yes in step S104), it proceeds to step S105.

[0067] The control unit 70 determines whether the flow channel outlet temperature T2 ≥ flow channel outlet temperature T1 or flow channel outlet temperature T3 ≥ flow channel outlet temperatures T1, T2 (step S105). For example, if the flow channel outlet temperature T2 ≥ flow channel outlet temperature T1 or flow channel outlet temperature T3 ≥ flow channel outlet temperatures T1, T2, then there is a possibility that multiple flow channels 211 are partially blocked in the electrolytic section 210 of the separators 25, 26. Thus, by determining whether the flow channel outlet temperature T2 ≥ flow channel outlet temperature T1 or flow channel outlet temperature T3 ≥ flow channel outlet temperatures T1, T2, the control unit 70 can determine whether the flow channels 211 are blocked in the electrolytic section 210 of the separators 25, 26.

[0068] If the control unit 70 determines that the flow path outlet temperature T2 ≥ flow path outlet temperature T1 or flow path outlet temperature T3 ≥ flow path outlet temperatures T1,T2 (Yes in step S105), it proceeds to step S106. That is, if the flow path 211 is blocked, even if the electrolyte flow rate is increased, the electrolyte will not flow easily through the blocked flow path 211, so the control unit 70 proceeds to step S106. The control unit 70 lowers the temperature of the electrolyte (step S106). For example, the control unit 70 lowers the temperature of the electrolyte by controlling the adjustment unit 60 so that the temperature of the electrolyte drops to a desired temperature, based on the inlet temperature of the separator 26 measured by the first temperature sensor 81 and the flow path outlet temperatures of the multiple flow paths 211 measured by the second temperature sensor 82. As a result, the water electrolysis device 1 lowers the temperature of the electrolysis unit 210 by lowering the temperature of the electrolyte, because the temperature of the electrolysis unit 210 is locally high. When the processing in step S106 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0069] Furthermore, if the control unit 70 determines that the flow path outlet temperature T2 ≥ flow path outlet temperature T1 or flow path outlet temperature T3 ≥ flow path outlet temperatures T1,T2 is not true (No in step S105), 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, in the water electrolysis device 1, if there are many water electrolysis stacks 21 with high temperatures due to aging deterioration of the solid polymer electrolyte membrane 22, etc., it is necessary to lower the temperature of the water electrolysis stacks 21. For this reason, the water electrolysis device 1 determines whether the electrolyte flow rate has reached its upper limit.

[0070] If the control unit 70 determines that the flow rate of the electrolyte solution flowing through the water electrolysis cell 11 has reached its upper limit (Yes in step S107), it proceeds to step S106, which has already been described. Then, the control unit 70 lowers the temperature of the electrolyte solution (step S106). Once the process in step S106 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0071] Furthermore, if the control unit 70 determines that the flow rate of the electrolyte supplied to the water electrolysis cell 11 has not reached its upper limit (No in step S107), it proceeds to step S108. The control unit 70 increases the flow rate of the electrolyte (step S108). For example, 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 in order to lower the temperature of the water electrolysis stack 21. As a result, the water electrolysis device 1 lowers the temperature of the electrolysis unit 210 by increasing the flow rate of the electrolyte because the temperature of the electrolysis unit 210 is locally high. When the processing in step S108 is completed, the control unit 70 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 a desired 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. Once the control unit 70 confirms that the electrolyte temperature has decreased, it proceeds to step S110.

[0073] The control unit 70 determines whether or not to terminate (step S110). For example, the control unit 70 determines to terminate when termination conditions are met, such as the completion of water electrolysis or an external termination instruction. If the control unit 70 determines not to terminate (No in step S110), it continues the process by returning to step S101, which has already been described. If the control unit 70 determines to terminate (Yes in step S110), it terminates the processing procedure shown in Figure 8.

[0074] In this way, the water electrolysis device 1 measures the flow path outlet temperatures at multiple different locations using the second temperature sensor 82 and controls the temperature of the electrolysis unit 210 to remain below the heat resistance temperature of the solid polymer electrolyte membrane 22 by adjusting the inlet temperatures of the pair of separators 25 and 26. As a result, the water electrolysis device 1 can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by adjusting the electrolyte temperature when the temperature rises locally in the electrolysis unit 210 of the pair of separators 25 and 26. Consequently, the water electrolysis device 1 can raise the electrolyte temperature, thereby improving the performance of water electrolysis.

[0075] Furthermore, in the case of a localized temperature rise in the electrolysis section 210 of the pair of separators 25 and 26, the water electrolysis device 1 can keep the temperature of the electrolysis section 210 below the heat resistance temperature of the solid polymer electrolyte membrane 22, thereby reliably preventing damage to the solid polymer electrolyte membrane 22.

[0076] (Second Embodiment) Next, a second embodiment will be described. In the second embodiment, the basic configuration of the water electrolysis apparatus 1 is the same as that of the first embodiment, but the temperature measurement location is different from that of the first embodiment. In the second embodiment, the parts that are common to the configuration of the first embodiment will not be described. The water electrolysis apparatus 1 according to the second embodiment includes a water electrolysis cell 11, a power supply unit 12, a first electrolyte path 14, a first gas-liquid separation tank 15, an oxygen gas extraction path 16, a second electrolyte path 17, a second gas-liquid separation tank 18, a hydrogen gas extraction path 19, an adjustment unit 60, and a control unit 70.

[0077] Figure 9 is a diagram illustrating the functional configuration of a water electrolysis apparatus according to the second embodiment. As shown in Figure 9, the water electrolysis apparatus 1 according to the second embodiment further comprises 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, while the other configurations described above are omitted.

[0078] The third temperature sensor 83 is a temperature sensor capable of measuring the temperature of the external surface of the water electrolysis stack 21 corresponding to the outlets of a plurality of flow channels 211 formed in the electrolysis section 210 of the separators 25 and 26. The water electrolysis stack 21 is formed of a thermally conductive material, and heat is transferred from the electrolysis section 210 of the separators 25 and 26 to it. The third temperature sensor 83 is provided on the external surface of the water electrolysis stack 21 corresponding to the vicinity of the outlets of the flow channels 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 thermometer, a thermocouple, etc. The third temperature sensor 83 supplies temperature information 722 that can identify the measured temperature of the external surface of the water electrolysis stack 21 to the control unit 70.

[0079] Figure 10 is a graph showing the temperature inside and outside the water electrolysis stack 21. In Figure 10, the vertical axis represents the temperature inside the water electrolysis stack 21, and the horizontal axis represents the temperature of the outside surface of the water electrolysis stack 21.

[0080] Graph G41 in Figure 10 shows the relationship between the internal temperature of the water electrolysis stack 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 temperature difference between the temperature near the outlet of the flow path 211 on the outside of the water electrolysis stack 21 and the temperature near the outlet of the flow path 211 of the separators 25 and 26 inside the water electrolysis stack 21 is a maximum of 7°C. In other words, Graph G41 shows that there is a proportional relationship between the external surface temperature measured by the third temperature sensor 83 and the internal temperature of the water electrolysis stack 21.

[0081] The water electrolysis device 1 stores estimated information 723 corresponding to graph G41 in the storage unit 72, thereby estimating the temperature near the outlet of the flow path 211 in the electrolysis section 210 of the separators 25 and 26 from the temperature of the external surface measured by the third temperature sensor 83. The estimated information 723 contains information for estimating the flow path outlet temperatures of multiple flow paths 211, the temperature distribution near the outlets, etc., from the temperature of the external surface of the water electrolysis stack 21. For example, the estimated information 723 includes a lookup table that estimates the flow path outlet temperatures of multiple flow paths 211, the temperature distribution near the outlets, etc., from the temperature of the external surface of the water electrolysis stack 21. For example, the estimated information 723 includes information of a machine learning model that outputs the flow path outlet temperatures of multiple flow paths 211, the temperature distribution near the outlets, etc., when the temperature of the external surface of the water electrolysis stack 21 is input.

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

[0083] The water electrolysis device 1 stores estimated information 723 corresponding to the water electrolysis cell 11 equipped with multiple third temperature sensors 83 in the storage unit 72. This allows the water electrolysis device 1 to estimate the temperature distribution near the outlet of the flow path 211 in the electrolysis section 210 of multiple water electrolysis cells 11 at different locations in the stacking direction H of the water electrolysis stack 21, based on the temperature of the external surface measured by the multiple third temperature sensors 83.

[0084] (Control method for a water electrolysis apparatus according to the second embodiment) Figure 12 is a flowchart showing an example of a processing procedure of the control method executed by the water electrolysis apparatus according to the second embodiment. The processing procedure shown in Figure 12 is realized by the control unit 70 of the water electrolysis apparatus 1 executing the program 721. Steps S102 to S110 of the processing procedure shown in Figure 12 are the same as steps S102 to S110 shown in Figure 8.

[0085] As shown in Figure 12, the control unit 70 of the water electrolysis apparatus 1 measures the temperature of the external surface of the water electrolysis stack 21 using the third temperature sensor 83 (step S121). For example, the control unit 70 acquires the external surface temperature measured by the third temperature sensor 83 and stores it as temperature information 722 in the storage unit 72. When 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 electrolytic section 210 of the separators 25 and 26 based on the temperature of the external surface (step S122). For example, the control unit 70 estimates the flow path outlet temperatures T1, T2, and T3 in the electrolytic section 210 based on the temperature of the external surface measured in step S121 and the estimated information 723 in the storage unit 72, and stores them in the storage unit 72 as temperature information 722. When the processing in step S122 is completed, the control unit 70 proceeds to step S102, which has already been described.

[0087] The control unit 70 determines whether the flow channel outlet temperatures T1, T2, and T3 are equal to or greater than the first heat resistance temperature (step S102). If the control unit 70 determines that the flow channel outlet temperatures T1, T2, and T3 are equal to or greater than the first heat resistance temperature (Yes in step S102), it proceeds to step S103.

[0088] The control unit 70 reduces the current or stops the electrolysis operation (step S103). Once the process in step S103 is completed, the control unit 70 proceeds to step S110, which will be described later.

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

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

[0091] Furthermore, if the control unit 70 determines that the flow path outlet temperature T2 ≥ flow path outlet temperature T1 or flow path outlet temperature T3 ≥ flow path outlet temperatures T1,T2 is not true (No in step S105), the process proceeds to step S107. The control unit 70 determines whether the flow rate of the electrolyte has reached its upper limit (step S107). If the control unit 70 determines that the flow rate of the electrolyte flowed through the water electrolysis cell 11 has reached its upper limit (Yes in step S107), the process proceeds to step S106, which has already been described. Then, the control unit 70 lowers the temperature of the electrolyte (step S106). Once the process in step S106 is completed, the control unit 70 proceeds to step S109, which will be described later.

[0092] Furthermore, if the control unit 70 determines that the flow rate of the electrolyte solution flowed through the water electrolysis cell 11 has not reached the upper limit (No in step S107), it proceeds to step S108. The control unit 70 increases the flow rate of the electrolyte solution (step S108). When the process in step S108 is completed, the control unit 70 proceeds to step S109.

[0093] The control unit 70 confirms the decrease in electrolyte temperature (step S109). Once the control unit 70 confirms the decrease in electrolyte temperature, it proceeds to step S110.

[0094] The control unit 70 determines whether to terminate or not (step S110). If the control unit 70 determines not to terminate (No in step S110), it returns to step S121, which has already been described, and continues the process. If the control unit 70 determines to terminate (Yes in step S110), it terminates the processing procedure shown in Figure 12.

[0095] As described above, the water electrolysis apparatus 1 according to the second embodiment measures the temperature of the outer surface of the water electrolysis stack 21 corresponding to the vicinity of the outlet of the flow path 211 of the electrolysis section 210 of the separators 25 and 26 using the third temperature sensor 83, and estimates the flow path outlet temperatures at multiple locations of the electrolysis section 210 of the separators 25 and 26 from the temperature of the outer surface. Based on the flow path outlet temperatures at multiple locations, the water electrolysis apparatus 1 can adjust the temperature of the electrolysis section 210 to reduce the temperature rise of the electrolysis section of the separator. As a result, when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26, the water electrolysis apparatus 1 can control the temperature of the electrolyte and prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature. As a result, the water electrolysis apparatus 1 can raise the temperature of the electrolyte and improve the performance of water electrolysis. Furthermore, since the water electrolysis device 1 only needs to measure the temperature of the external surface of the water electrolysis stack 21, it is not necessary to install the third temperature sensor 83 in the electrolysis section 210 of the separators 25 and 26, thereby simplifying the device configuration.

[0096] (Third embodiment) Next, a third embodiment will be described. In the third embodiment, the basic configuration of the water electrolysis apparatus 1 is the same as that of the first embodiment, but the temperature measurement location is different from that of the first embodiment. In the third embodiment, the parts that are common to the configuration of the first embodiment will not be described. The water electrolysis apparatus 1 according to the third embodiment includes a water electrolysis cell 11, a power supply unit 12, a first electrolyte path 14, a first gas-liquid separation tank 15, an oxygen gas extraction path 16, a second electrolyte path 17, a second gas-liquid separation tank 18, a hydrogen gas extraction path 19, an adjustment unit 60, and a control unit 70.

[0097] Figure 13 is a diagram illustrating the functional configuration of a water electrolysis apparatus according to the third embodiment. As shown in Figure 13, the water electrolysis apparatus 1 according to the third embodiment further comprises 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, 26, while other configurations are omitted. The second temperature sensor 82 has a second temperature sensor 82a, a second temperature sensor 82b, and a second temperature sensor 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 from the start of electrolysis (min). Figure 14 shows the temperature changes of the channel outlet temperatures T1 and T2 among the channel outlet temperatures T1, T2, and T3 of the electrolytic section 210 of separators 25 and 26. Graph G51a shows the temperature change of the channel outlet temperature T1 from the start of electrolysis under normal conditions. Graph G51b shows the temperature change of the channel outlet temperature T1 from the start of electrolysis under abnormal conditions where partial blockage of channel 211 occurs. Graph G52a shows the temperature change of the channel outlet temperature T2 from the start of electrolysis under normal conditions. Graph G52b shows the temperature change of the channel outlet temperature T1 from the start of electrolysis under abnormal conditions where partial blockage of channel 211 occurs. As shown in Figure 14, the temperature measured by the second temperature sensor 82 differs from the temperature change from the start of electrolysis when the electrolytic section 210 of the separators 25 and 26 is functioning normally or abnormally. Therefore, the water electrolysis apparatus 1 according to the third embodiment can control the water electrolysis operation based on the time rate of change of the flow path outlet temperature measured in the flow path 211 of the electrolytic section 210 of the separators 25 and 26.

[0099] As shown in Figure 13, the water electrolyzer 1 stores temperature change information 724 in the storage unit 72 that can identify the temperature changes of the flow channel outlet temperatures T1, T2, and T3 from the start of electrolysis under normal conditions. The temperature change information 724 contains information that can identify the temperature changes of the flow channel outlet temperatures T1, T2, and T3 from the start of electrolysis to the steady temperature. The temperature change information 724 may also contain information that can identify the temperature changes of the flow channel outlet temperatures T1, T2, and T3 under abnormal conditions.

[0100] (Control method at the start of operation of a water electrolysis apparatus according to the third embodiment) Figure 15 is a flowchart showing an example of the processing procedure for the control method at the start of electrolysis executed by the water electrolysis apparatus according to the third embodiment. The processing procedure shown in Figure 15 is realized by the control unit 70 of the water electrolysis apparatus 1 executing the program 721.

[0101] As shown in Figure 15, the control unit 70 of the water electrolysis apparatus 1 starts the electrolysis operation (step S200). For example, the control unit 70 opens the first water supply valve 42 and the second water supply valve 44 and supplies electrolyte to the first electrolyte path 14 and the second electrolyte path 17 of the anode and cathode of the water electrolysis cell 11 via the first water supply path 41 and the second water supply path 43. At the same time, the control unit 70 operates the first circulation pump 31 and the second circulation pump 32 to circulate the electrolyte. The control unit 70 starts supplying power to the water electrolysis cell 11 and starts the electrolysis reaction by the water electrolysis cell 11. The control unit 70 controls the flow rate of the electrolyte by the first circulation pump 31 and the second circulation pump 32 according to the current supplied to the water electrolysis cell 11. When step S200 is completed, the control unit 70 proceeds to step S201.

[0102] The control unit 70 continuously measures the flow channel outlet temperatures T1, T2, and T3 from the start of electrolysis in the electrolytic section 210 of the separators 25 and 26 (step S201). For example, the control unit 70 continuously acquires the flow channel outlet temperatures T1, T2, and T3 measured by the second temperature sensor 82 and stores them in the storage unit 72 as temperature information 722 until a constant temperature is reached. The control unit 70 calculates the rate of temperature change per unit of time until a constant temperature is reached and sets it in the temperature information 722 in association with the flow channel outlet temperatures T1, T2, and T3. When 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 change per unit time of the flow channel outlet temperatures T1, T2, T3 indicated by the temperature information 722 with the temperature change of the flow channel outlet temperatures T1, T2, T3 from the start of electrolysis to the steady temperature indicated by the temperature change information 724. If there are temperature changes that do not match or are not similar, the control unit 70 determines that the temperature change per unit time is abnormal. If the control unit 70 determines that the temperature change per unit time is abnormal (Yes in step S202), it proceeds to step S203.

[0104] The control unit 70 controls the flow rate of the electrolyte (step S203). For example, the control unit 70 controls the flow rate of the electrolyte by the first circulation pump 31 and the second circulation pump 32 in accordance with the current supplied to the water electrolysis cell 11, thereby controlling the flow rate of the electrolyte based on a predetermined countermeasure. As a result, the water electrolysis device 1 can resolve the abnormality in the electrolysis unit 210 by controlling the flow rate of the electrolyte, as the temperature change in the electrolysis unit 210 is abnormal. When the process 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 (No in step S202), it proceeds to step S204. The control unit 70 determines whether the temperature change of the flow channel outlet temperature T1 is abnormal (step S204). For example, if the flow channel outlet temperature T1 in the temperature information 722 reaches the steady temperature faster than usual, the control unit 70 determines that the temperature change of the flow channel outlet temperature T1 is abnormal because it is possible that multiple flow channels 211 in the electrolytic section 210 of the separators 25 and 26 are blocked overall.

[0106] If the control unit 70 determines that the temperature change of the flow channel outlet temperature T1 is abnormal (Yes in step S204), it proceeds to step S205. The control unit 70 increases the flow rate of the electrolyte to the first flow rate (step S205). The first flow rate is a flow rate determined to resolve the overall blockage of the multiple flow channels 211. For example, the control unit 70 increases the flow rate of the electrolyte to the first flow rate by controlling the flow velocity of the electrolyte by the first circulation pump 31 and the second circulation pump 32 in accordance with the current supplied to the water electrolysis cell 11. As a result, the water electrolysis device 1 can resolve the abnormality related to the flow channel outlet temperature T1 by setting the flow rate of the electrolyte to the first flow rate because the temperature change of the flow channel outlet temperature T1 is abnormal. When the processing in step S205 is completed, the control unit 70 proceeds to step S208, which will be described later.

[0107] Furthermore, if the control unit 70 determines that the temperature change of the flow channel outlet temperature T1 is not abnormal (No in step S204), it proceeds to step S206. The control unit 70 determines whether the flow channel outlet temperature T2 reached the steady temperature earlier than the flow channel outlet temperature T1 (step S206). For example, if the flow channel outlet temperature T2 in the temperature information 722 reaches the steady temperature earlier than the flow channel outlet temperature T1 in the temperature information 722, the control unit 70 determines that the flow channel outlet temperature T2 reached the steady temperature earlier than the flow channel outlet temperature T1. If the control unit 70 determines that the flow channel outlet temperature T2 did not reach the steady temperature earlier than the flow channel outlet temperature T1 (No in step S206), it determines that there is no abnormality in the multiple flow channels 211 in the electrolytic unit 210, and proceeds to step S208, which will be described later.

[0108] Furthermore, if the control unit 70 determines that the flow path outlet temperature T2 has reached a steady temperature faster than the flow path outlet temperature T1 (Yes in step S206), it determines that there is a possibility that multiple flow paths 211 in the electrolytic section 210 of the separators 25 and 26 are partially blocked, and proceeds to step S207. The control unit 70 increases the flow rate of the electrolyte to a second flow rate (step S207). The second flow rate is a flow rate determined to resolve the partial blockage of multiple flow paths 211. For example, the control unit 70 increases the flow rate of the electrolyte to a second flow rate by controlling the flow velocity of the electrolyte by the first circulation pump 31 and the second circulation pump 32 in accordance with the current supplied to the water electrolysis cell 11. As a result, the water electrolysis device 1 can resolve the partial blockage of the flow paths 211 in the electrolytic section 210 by setting the flow rate of the electrolyte to a second flow rate. When the processing in step S207 is completed, the control unit 70 proceeds to step S208.

[0109] The control unit 70 determines whether or not to terminate (step S208). For example, the control unit 70 determines to terminate when the elapsed time from the start of electrolysis reaches a predetermined time. If the control unit 70 determines not to terminate (No in step S208), it continues the process by returning to step S201, which has already been described. If the control unit 70 determines to terminate (Yes in step S208), it terminates the processing procedure shown in Figure 15. Once the processing procedure shown in Figure 15 is completed, the control unit 70 controls the outlet temperature of the electrolytic section 210 of the pair of separators 25 and 26 using the control method described in the first embodiment.

[0110] As described above, the water electrolysis apparatus 1 according to the third embodiment measures the flow path outlet temperature at multiple different locations using the second temperature sensor 82, and controls the flow rate of the electrolyte supplied to the electrolysis unit 210 based on the time change indicated by the measurement results of the flow path outlet temperature. As a result, the water electrolysis apparatus 1 can determine the state of the electrolysis unit 210 of the pair of separators 25 and 26 from the temperature change since the start of electrolysis, and can change the flow rate of the electrolyte according to the state of the electrolysis unit 210. As a result, the water electrolysis apparatus 1 can contribute to resolving abnormalities in the state of the electrolysis unit 210 of the pair of separators 25 and 26 at the start of electrolysis in the apparatus, and can also suppress deterioration of the state of the electrolysis unit 210, thereby maintaining the performance of water electrolysis.

[0111] In the third embodiment, the water electrolysis apparatus 1 may be configured to control the flow rate of the electrolyte solution flowing to the electrolysis unit 210 based on the temperature change of the external surface of the water electrolysis cell 11 measured by the third temperature sensor 83 shown in the second embodiment, when the external ambient temperature is constant. Alternatively, the water electrolysis apparatus 1 in the third embodiment may further include a third temperature sensor 83, and be configured to control the flow rate of the electrolyte solution flowing to the electrolysis unit 210 based on the temperature change measured by the second temperature sensor 84 and the third temperature sensor 83.

[0112] The water electrolysis apparatus 1 according to the first to third embodiments described above may also include a function to determine the state of the electrolysis section 210 of a pair of separators 25 and 26 based on the measured flow path outlet temperature and to notify an external device of the determination result.

[0113] (effect) A water electrolysis apparatus 1 according to a first aspect of this disclosure includes a water electrolysis stack 21 having a water electrolysis cell 11 in which a solid polymer electrolyte membrane 22 is arranged between a pair of separators 25, 26, which electrolyzes an electrolyte using the water electrolysis cell 11; 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) that circulate and supply the electrolyte to the water electrolysis cell 11; a first temperature sensor 81 capable of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21; a second temperature sensor 82 capable of measuring the flow path outlet temperature of the electrolyte flowing through the outlets of a plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25, 26; and a control unit 70 that performs control to adjust at least one of the flow rate, temperature, and current amount of the electrolyte to the electrolysis section 210 in order to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26, based on the inlet temperature of the first temperature sensor 81 and the flow path outlet temperature of the second temperature sensor 82. As a result, the water electrolysis device 1 can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by adjusting the temperature of the electrolyte when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26. Consequently, the water electrolysis device 1 can raise the temperature of the electrolyte, thereby improving the performance of water electrolysis.

[0114] In the water electrolysis apparatus 1 according to a second aspect of this disclosure, the control unit 70 controls at least one of the flow rate, temperature, and current of the electrolyte supplied to the electrolysis unit 210 so that the temperature that rises in a part of the electrolysis unit 210 of the separators 25, 26 is below the heat resistance temperature of the solid polymer electrolyte membrane 22. As a result, the water electrolysis apparatus 1 can ensure that when the temperature rises locally in the electrolysis unit 210 of the pair of separators 25, 26, the temperature of the electrolysis unit 210 is below the heat resistance temperature of the solid polymer electrolyte membrane 22, thereby reliably preventing damage to the solid polymer electrolyte membrane 22.

[0115] In the water electrolysis apparatus 1 according to the third aspect of this disclosure, the second temperature sensor 82 measures the flow channel outlet temperature in the separators 25 and 26 at multiple different measurement positions in the width direction of the electrolysis unit 210, which has multiple flow channels 211 arranged side by side. As a result, the water electrolysis apparatus 1 can grasp the temperature distribution of the electrolysis unit 210 from the flow channel outlet temperature measured by the second temperature sensor 82, so that the temperature of the electrolyte can be appropriately adjusted, which can further contribute to preventing damage to the solid polymer electrolyte membrane 22.

[0116] In the water electrolysis apparatus 1 according to the fourth aspect of this disclosure, an adjustment unit 60 is further provided to adjust the temperature of the electrolyte supplied to the inlet of the water electrolysis stack 21. The control unit 70 lowers the temperature of the electrolyte relative to the electrolysis section 210 in 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, so as to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26. As a result, the water electrolysis apparatus 1 can rapidly lower the temperature of the electrolyte relative to the electrolysis section 210 by providing the adjustment unit 60 at the inlet of the water electrolysis stack 21, thereby contributing even more to preventing damage to the solid polymer electrolyte membrane 22.

[0117] In the water electrolysis apparatus 1 according to the fifth aspect of this disclosure, the control unit 70 controls the flow rate of the electrolyte to the electrolysis unit 210 based on the temperature change from the start of electrolysis measured by the second temperature sensor 82. As a result, the water electrolysis apparatus 1 can help resolve abnormal conditions in the electrolysis unit 210 of the pair of separators 25 and 26 at the start of electrolysis in the apparatus, and can also suppress deterioration of the condition of the electrolysis unit 210, thereby maintaining the performance of water electrolysis.

[0118] In the water electrolysis apparatus 1 according to the sixth aspect of this disclosure, the control unit 70 increases the flow rate of electrolyte to the electrolysis unit 210 when the temperature change from the start of electrolysis measured by the second temperature sensor 82 indicates blockage of the electrolysis unit 210. As a result, the water electrolysis apparatus 1 can quickly resolve abnormal conditions in the electrolysis unit 210 of the pair of separators 25 and 26 at the start of electrolysis in the apparatus, thereby maintaining the performance of water electrolysis.

[0119] A water electrolysis apparatus 1 according to a seventh aspect of this disclosure includes a water electrolysis stack 21 having a water electrolysis cell 11 in which a solid polymer electrolyte membrane 22 is arranged between a pair of separators 25, 26, which electrolyzes an electrolyte using the water electrolysis cell 11; 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) that circulate and supply the electrolyte to the water electrolysis cell 11; a first temperature sensor 81 capable of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21; a third temperature sensor 83 capable of measuring the temperature of the outer surface of the water electrolysis stack 21 corresponding to the outlets of a plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25, 26; and a control unit 70 that performs control to adjust at least one of the flow rate, temperature, and current amount of the electrolyte to the electrolysis section 210 in order to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26, based on the flow path outlet temperature of the outlets of the plurality of flow paths 211 estimated from the inlet temperature and the temperature of the outer surface. As a result, the water electrolysis device 1 can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by controlling the temperature of the electrolyte when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26. Consequently, the water electrolysis device 1 can raise the temperature of the electrolyte, thereby improving the performance of water electrolysis. Furthermore, since the water electrolysis device 1 only needs to measure the temperature of the external surface of the water electrolysis stack 21, there is no need to install a third temperature sensor 83 in the electrolysis section 210 of the separators 25 and 26, thus simplifying the device configuration.

[0120] In the water electrolysis apparatus 1 according to the eighth aspect of this disclosure, the water electrolysis stack 21 is made up of multiple water electrolysis cells 11 stacked in the stacking direction, and the third temperature sensor 83 is provided on the outer surface of the water electrolysis stack 21 at measurement positions including the center and ends in the stacking direction. As a result, when the water electrolysis apparatus 1 stacks multiple water electrolysis cells 11, it is not necessary to provide a third temperature sensor 83 for each of the multiple water electrolysis cells 11, thus suppressing the increase in the number of third temperature sensors 83 and reducing the cost of the apparatus.

[0121] A control method for a water electrolysis apparatus 1 according to a ninth aspect of the present disclosure comprises a water electrolysis stack 21 having a water electrolysis cell 11 in which a solid polymer electrolyte membrane 22 is arranged between a pair of separators 25, 26, and which electrolyzes an electrolyte using the water electrolysis cell 11; 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) that circulate and supply the electrolyte to the water electrolysis cell 11, the control method for a water electrolysis apparatus 1 comprising: a step of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21 with a first temperature sensor 81; a step of measuring the flow path outlet temperature of the electrolyte flowing through the outlets of a plurality of flow paths 211 formed in the electrolysis section 210 of the separators 25, 26 with a second temperature sensor 82; and a step of adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolysis section 210 based on the inlet temperature and the flow path outlet temperature, so as to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26. As a result, the control method can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by adjusting the electrolyte temperature when the temperature rises locally in the electrolytic section 210 of the pair of separators 25 and 26. Consequently, the control method can raise the electrolyte temperature, thereby improving the performance of water electrolysis.

[0122] A control method for a water electrolysis apparatus 1 according to a tenth aspect of this disclosure comprises a water electrolysis stack 21 having a water electrolysis cell 11 in which a solid polymer electrolyte membrane 22 is arranged between a pair of separators 25, 26, and which electrolyzes an electrolyte using the water electrolysis cell 11; 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) that circulate and supply the electrolyte to the water electrolysis cell 11, wherein the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21 is set to a first temperature The control method includes the steps of: measuring with sensor 81; measuring the temperature of the outer surface of the water electrolysis stack 21 corresponding to the outlets of a plurality of flow channels 211 formed in the electrolytic section 210 of separators 25, 26 with a third temperature sensor 83; and adjusting at least one of the electrolyte flow rate, temperature, and current amount to the electrolytic section 210 to reduce the temperature that has risen in a part of the electrolytic section 210 of separators 25, 26, based on the flow channel outlet temperature of the outlets of the plurality of flow channels 211 estimated from the inlet temperature and the outer surface temperature. As a result, the control method can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by controlling the temperature of the electrolyte when the temperature rises locally in the electrolytic section 210 of the pair of separators 25, 26. Furthermore, since the control method only requires measuring the temperature of the external surface of the water electrolysis stack 21, it becomes unnecessary to install the third temperature sensor 83 in the electrolysis section 210 of the separators 25 and 26, thereby simplifying the device configuration.

[0123] A program according to the eleventh aspect of this disclosure causes a water electrolysis apparatus 1 to perform the following steps: measure the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21 with a first temperature sensor 81; measure the flow outlet temperature of the electrolyte flowing through the outlets of a plurality of flow channels 211 formed in the electrolysis section 210 of the separators 25, 26 with a second temperature sensor 82; and adjust at least one of the flow rate, temperature, and current of the electrolyte to the electrolysis section 210 so as to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25, 26. As a result, the program can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by adjusting the electrolyte temperature using the water electrolysis device 1 when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26. Consequently, the control method can raise the electrolyte temperature, thereby improving the performance of water electrolysis in the water electrolysis device 1.

[0124] A program according to a twelfth aspect of this disclosure comprises a water electrolysis device 1 having a water electrolysis cell 11 in which a solid polymer electrolyte membrane 22 is arranged between a pair of separators 25, 26, a water electrolysis stack 21 that electrolyzes an electrolyte using the water electrolysis cell 11, 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) that circulate and supply the electrolyte to the water electrolysis cell 11, wherein the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack 21 is measured by a first temperature sensor 81. The program includes the steps of measuring, measuring the temperature of the outer surface of the water electrolysis stack 21 corresponding to the outlets of a plurality of flow channels 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 electrolyte flow rate, temperature, and current amount to the electrolysis section 210 to reduce the temperature that has risen in a part of the electrolysis section 210 of the separators 25 and 26, based on the flow channel outlet temperatures of the outlets of the plurality of flow channels 211 estimated from the inlet temperature and the outer surface temperature. As a result, the program can prevent damage to the solid polymer electrolyte membrane 22 due to a rise in temperature by controlling the temperature of the electrolyte with the water electrolysis device 1 when the temperature rises locally in the electrolysis section 210 of the pair of separators 25 and 26. Furthermore, since the program only needs to measure the temperature of the external surface of the water electrolysis stack 21 in the water electrolysis device 1, it becomes unnecessary to install the third temperature sensor 83 in the electrolysis section 210 of the separators 25 and 26, thereby simplifying the configuration of the water electrolysis device 1.

[0125] Although embodiments of the present disclosure have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the embodiments described above. [Explanation of Symbols]

[0126] 1 Water electrolysis device 11 Water electrolysis cell 12 Power supply section 14. First Electrolyte Pathway 14a, 17a Entrance Route 14b, 17b Exit routes 15. First gas-liquid separation tank 15a, 18a filters 16. Oxygen gas extraction route 17. Second electrolyte pathway 18. Second gas-liquid separation tank 19. Hydrogen gas extraction route 20 End Plates 21 Water Electrolysis Stack 22 Solid polymer electrolyte membrane 23 Anode side 24 Cathode side 25, 26 Separator 27,28 Power feeder 29a Inlet pipe section 29b Outlet pipe section 31. First circulation pump 32. Second circulation pump 33 Hydrogen control valve 34. Auxiliary routes 35 Buffer Tank 36 Water discharge 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 section 70 Control Unit 72 Memory section 81. First temperature sensor 82, 82a, 82b, 82c Second temperature sensor 83 Third temperature sensor 200 main unit 200A,200B area 201 Fixed part 210 Electrolytic section 211 Flow channel 220 Electrolyte inlet 230 Electrolyte outlet 240 packing 721 Programs 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 outlet temperature W (width direction)

Claims

1. A water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is placed between a pair of separators, and using the water electrolysis cell to electrolyze an electrolyte, A power supply unit electrically connected to the aforementioned water electrolysis stack, An electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, A first temperature sensor capable of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack, A second temperature sensor capable of measuring the flow outlet temperature of the electrolyte solution flowing through the outlets of multiple flow channels formed in the electrolytic section of the separator, A control unit that controls the flow rate, temperature, and current of the electrolyte to the electrolytic section in order to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the inlet temperature of the first temperature sensor and the outlet temperature of the flow path of the second temperature sensor. A water electrolysis device equipped with the following features.

2. The water electrolysis apparatus according to claim 1, wherein the control unit controls at least one of the flow rate, temperature, and current of the electrolyte to the electrolysis unit so that the temperature risen in a part of the electrolysis unit of the separator is below the heat resistance temperature of the solid polymer electrolyte membrane.

3. The water electrolysis apparatus according to claim 2, wherein the measurement positions of the flow path outlet temperature in the separator are multiple different measurement positions in the width direction of the electrolysis unit in which multiple flow paths are arranged.

4. The system further includes an adjustment unit for adjusting the temperature of the electrolyte supplied to the inlet of the water electrolysis stack, The water electrolysis apparatus according to claim 3, wherein the control unit lowers the temperature of the electrolyte relative to the electrolysis section in the adjustment section so as to lower the temperature that has risen in a part of the electrolysis section of the separator, based on the inlet temperature of the first temperature sensor and the flow path outlet temperature of the second temperature sensor.

5. The water electrolysis apparatus according to claim 1, wherein the control unit controls the flow rate of the electrolyte to be supplied to the electrolysis unit based on the temperature change since the start of electrolysis measured by the second temperature sensor.

6. The water electrolysis apparatus according to claim 5, wherein the control unit increases the flow rate of the electrolyte supplied to the electrolysis unit when the temperature change since the start of electrolysis, as measured by the second temperature sensor, indicates blockage of the electrolysis unit.

7. A water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is placed between a pair of separators, and using the water electrolysis cell to electrolyze an electrolyte, A power supply unit electrically connected to the aforementioned water electrolysis stack, An electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, A first temperature sensor capable of measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack, A third temperature sensor capable of measuring the temperature of the external surface of the water electrolysis stack corresponding to the outlets of multiple flow channels formed in the electrolytic section of the separator, A control unit that controls the flow rate, temperature, and current of the electrolyte to the electrolytic section in order to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the flow rate outlet temperature of the outlets of the multiple flow paths estimated from the inlet temperature and the temperature of the outer surface, A water electrolysis device equipped with the following features.

8. The water electrolysis stack comprises a plurality of water electrolysis cells stacked in the stacking direction. The water electrolysis apparatus according to claim 7, wherein the third temperature sensor is provided on the outer surface of the water electrolysis stack at a measurement position including the center and the ends in the stacking direction.

9. A control method for a water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, which electrolyzes an electrolyte solution using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte solution path for circulating and supplying the electrolyte solution to the water electrolysis cell, The steps include: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; The steps include: measuring the outlet temperature of the electrolyte flowing through the outlets of multiple channels formed in the electrolytic section of the separator using a second temperature sensor; Based on the inlet temperature and the flow path outlet temperature, the step of adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section to reduce the temperature that has risen in a part of the electrolytic section of the separator, A control method including

10. A control method for a water electrolysis apparatus comprising: a water electrolysis stack having a water electrolysis cell in which a solid polymer electrolyte membrane is arranged between a pair of separators, which electrolyzes an electrolyte solution using the water electrolysis cell; a power supply unit electrically connected to the water electrolysis stack; and an electrolyte solution path for circulating and supplying the electrolyte solution to the water electrolysis cell, The steps include: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; The steps include: measuring the temperature of the outer surface of the water electrolysis stack corresponding to the outlets of the multiple flow channels formed in the electrolytic section of the separator using a third temperature sensor; The steps include adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section in order to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the flow rate outlet temperature of the outlets of the multiple flow paths estimated from the inlet temperature and the temperature of the outer surface, A control method including

11. A water electrolysis apparatus comprising a water electrolysis stack having a water electrolysis cell with a solid polymer electrolyte membrane placed between a pair of separators, a power supply unit electrically connected to the water electrolysis stack, and an electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, The steps include: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; The steps include: measuring the outlet temperature of the electrolyte flowing through the outlets of multiple channels formed in the electrolytic section of the separator using a second temperature sensor; Based on the inlet temperature and the flow path outlet temperature, the step of adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section to reduce the temperature that has risen in a part of the electrolytic section of the separator, A program that executes something.

12. A water electrolysis apparatus comprising a water electrolysis stack having a water electrolysis cell with a solid polymer electrolyte membrane placed between a pair of separators, a power supply unit electrically connected to the water electrolysis stack, and an electrolyte path for circulating and supplying the electrolyte to the water electrolysis cell, The steps include: measuring the inlet temperature of the electrolyte flowing through the inlet of the water electrolysis stack with a first temperature sensor; The steps include: measuring the temperature of the outer surface of the water electrolysis stack corresponding to the outlets of the multiple flow channels formed in the electrolytic section of the separator using a third temperature sensor; The steps include adjusting at least one of the flow rate, temperature, and current of the electrolyte to the electrolytic section in order to reduce the temperature that has risen in a part of the electrolytic section of the separator, based on the flow rate outlet temperature of the outlets of the multiple flow paths estimated from the inlet temperature and the temperature of the outer surface, A program that executes something.

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