JP5341547B2 - Water electrolysis system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out water electrolysis by easily and surely detecting presence or absence of the leakage of hydrogen from an electrolyte membrane. <P>SOLUTION: The water electrolysis system 10 includes water electrolysis equipment 12 for producing high pressure hydrogen by the electrolysis of pure water and water circulation equipment 16 for supplying pure water to the electrolysis equipment 12 and circulating and supplying the water discharged from the water electrolysis equipment 12 to the water electrolysis equipment 12. The water circulation equipment 16 includes an oxygen side gas/liquid separator 78 for separating water and oxygen discharged from the water electrolysis equipment 12, a pressure sensor 86 for detecting the pressure of a mixed fluid of water with oxygen fed to the oxygen side gas/liquid separator 78 from the water electrolysis equipment 12 and a controller 22 for deciding the presence or absence of the leakage of hydrogen based on the pressure detected by the pressure sensor 86. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention provides a water electrolysis apparatus in which a power feeding body is provided on both sides of an electrolyte membrane, electrolyzes water to generate oxygen in one power feeding body, and generates hydrogen in the other power feeding body, and the water electrolysis apparatus The present invention relates to a water electrolysis system comprising a water circulation device that circulates and supplies excess water discharged from the water to the water electrolysis device.

  For example, in a polymer electrolyte fuel cell, a fuel gas (a gas containing mainly hydrogen, such as hydrogen gas) is supplied to the anode side electrode, while an oxidant gas (mainly containing oxygen) is supplied to the cathode side electrode. By supplying a gas (for example, air), direct current electric energy is obtained.

  In general, a water electrolysis apparatus is employed to produce hydrogen gas that is a fuel gas. This water electrolysis apparatus uses a solid polymer electrolyte membrane (ion exchange membrane) in order to decompose water and generate hydrogen (and oxygen). Electrode catalyst layers are provided on both sides of the solid polymer electrolyte membrane to form an electrolyte membrane / electrode structure, and a power feeder is provided on both sides of the electrolyte membrane / electrode structure. It is configured. That is, the unit is configured substantially in the same manner as the above fuel cell.

  Therefore, in a state where a plurality of units are stacked, a voltage is applied to both ends in the stacking direction, and water is supplied to the anode-side power feeding body. For this reason, water is decomposed and hydrogen ions (protons) are generated on the anode side of the electrolyte membrane / electrode structure, and the hydrogen ions permeate the solid polymer electrolyte membrane and move to the cathode side to bond with electrons. Thus, hydrogen is produced. On the other hand, on the anode side, oxygen produced together with hydrogen ions is discharged from the unit with excess water.

  As this type of water electrolysis system, for example, a polymer electrolyte water electrolysis device disclosed in Patent Document 1 is known. As shown in FIG. 7, this solid polymer type water electrolysis apparatus electrolyzes water using a polymer electrolyte membrane, generates water at the anode and hydrogen at the cathode, and the water electrolysis tank 1. The hydrogen gas-liquid separator 2 for separating hydrogen and water generated at the cathode of the water, the oxygen gas-liquid separator 3 for separating oxygen and water generated at the anode of the water electrolysis tank 1, and the oxygen gas-liquid separation A water circulation line 4 for supplying water from the vessel 3 to the water electrolyzer 1, an ion exchanger 5 for treating the supply water newly supplied to the water electrolyzer 1, and pure water for storing water after the ion exchange treatment A tank 6, a supply pump 7 for sending water from the pure water tank 6 to the oxygen gas-liquid separator 3, a part of the circulating water in the water circulation line 4 is taken out and processed, and the treated water is converted into the oxygen gas And a branch line 8 to be sent to the liquid separator 3. The water circulation line 4 includes a circulation pump 9 that circulates water by supplying water from the oxygen gas-liquid separator 3 to the water electrolysis tank 1.

JP 2002-173788 A

  By the way, in order to generate high-pressure hydrogen, the water electrolysis system employs a differential pressure generation system that maintains water and generated oxygen at normal pressure while maintaining generated hydrogen at a high pressure. In this differential pressure generation method, for example, hydrogen generated at the cathode of the water electrolysis layer 1 has a higher pressure than oxygen generated at the anode, so that this hydrogen may leak to the anode side through the solid polymer electrolyte membrane. is there.

  The present invention solves this type of problem, and provides a water electrolysis system capable of easily and reliably detecting the presence or absence of hydrogen leakage from an electrolyte membrane and capable of performing good water electrolysis. With the goal.

  The present invention provides a water electrolysis apparatus in which a power feeding body is provided on both sides of an electrolyte membrane, electrolyzes water to generate oxygen in one power feeding body, and generates hydrogen in the other power feeding body, and the water electrolysis apparatus The present invention relates to a water electrolysis system comprising a water circulation device that circulates and supplies surplus water discharged from the water to the water electrolysis device.

  The water circulation device includes a gas-liquid separation mechanism that separates a mixed fluid of water and oxygen discharged from the water electrolysis device into the water and oxygen, the water sent from the water electrolysis device to the gas-liquid separation mechanism, and the water A pressure detection mechanism for detecting the pressure of the mixed fluid of oxygen; and a control unit for determining whether or not hydrogen leaks from the electrolyte membrane based on the pressure detected by the pressure detection mechanism.

  Moreover, it is preferable that the control unit determines that there is hydrogen leakage when the detected pressure exceeds a predetermined value.

  Furthermore, it is preferable that the control unit determine that there is hydrogen leakage when the detected rate of increase in pressure exceeds a predetermined value.

  Furthermore, in the present invention, the water circulation device includes a gas-liquid separation mechanism that separates a mixed fluid of water and oxygen discharged from the water electrolysis device into the water and the hydrogen, and the gas-liquid separation separated from the water. A pressure detection mechanism that detects the pressure of the oxygen discharged from the mechanism; and a control unit that determines whether hydrogen leaks from the electrolyte membrane based on the pressure detected by the pressure detection mechanism.

  Moreover, it is preferable that the control unit determines that there is hydrogen leakage when the detected pressure exceeds a predetermined value.

  Furthermore, it is preferable that the control unit determine that there is hydrogen leakage when the detected rate of increase in pressure exceeds a predetermined value.

  According to the present invention, the pressure of the mixed fluid of water and oxygen sent from the water electrolysis apparatus to the gas-liquid separation mechanism is detected, and the presence or absence of hydrogen leakage from the electrolyte membrane is determined based on this pressure. In the water circulation device, since a constant flow of circulating water is circulated, the circulating water pressure also fluctuates within a certain range. Therefore, even if hydrogen leakage is slight, it is possible to reliably detect fluctuations in the circulating water pressure (water and oxygen pressure).

  For example, when determining the presence or absence of hydrogen leakage by detecting the pressure of the generated hydrogen, the leakage cannot be reliably detected unless the amount of hydrogen leakage reaches a considerable amount. On the other hand, when the presence or absence of hydrogen leakage is determined by detecting the concentration of hydrogen contained in the discharged oxygen, the leakage cannot be detected if the hydrogen leakage is unsteady.

  Thus, by detecting the pressure of the mixed fluid of water and oxygen sent from the water electrolysis device to the gas-liquid separation mechanism, it is possible to easily and reliably detect the presence or absence of hydrogen leakage from the electrolyte membrane. Water electrolysis can be performed.

  Furthermore, according to the present invention, the pressure of oxygen separated from water and discharged from the gas-liquid separation mechanism is detected, and based on this pressure, the presence or absence of hydrogen leakage from the electrolyte membrane is determined. Since the pressure (back pressure) of oxygen discharged from the gas-liquid separation mechanism is smaller than the fluctuation range of the circulating water pressure, the fluctuation of the oxygen pressure can be reliably detected even if hydrogen leakage is slight. Is possible. For this reason, the presence or absence of hydrogen leakage from the electrolyte membrane can be detected easily and reliably, and a good water electrolysis process can be performed.

It is a schematic structure explanatory view of a water electrolysis system concerning a 1st embodiment of the present invention. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said water electrolysis system. FIG. 4 is a relationship diagram of pressure and time of a mixed fluid of discharged water and oxygen at the time of hydrogen leakage. It is a schematic structure explanatory drawing of the water electrolysis system concerning a 2nd embodiment of the present invention. FIG. 5 is a relationship diagram of oxygen pressure and time when hydrogen leaks. It is schematic structure explanatory drawing of the water electrolysis system which concerns on the 3rd Embodiment of this invention. 1 is a schematic explanatory diagram of a solid polymer type water electrolysis apparatus disclosed in Patent Document 1. FIG.

  As shown in FIG. 1, a water electrolysis system 10 according to a first embodiment of the present invention includes a water electrolysis apparatus 12 that produces high-pressure hydrogen (higher than normal pressure) by electrolyzing pure water, Pure water generated from city water is supplied via the water supply device 14, and the pure water is supplied to the water electrolysis device 12, and surplus water discharged from the water electrolysis device 12 is converted into the water. A water circulation device 16 that circulates and supplies to the electrolysis device 12, a hydrogen side gas-liquid separator 18 that removes moisture contained in the high-pressure hydrogen led out from the water electrolysis device 12, and a supply from the hydrogen side gas-liquid separator 18 A hydrogen dehumidifier 20 that adsorbs and removes moisture contained in hydrogen to be removed and a controller (control unit) 22 are provided.

  The water electrolysis apparatus 12 constitutes a high-pressure hydrogen production apparatus, and a plurality of unit cells 24 are stacked. At one end of the unit cells 24 in the stacking direction, a terminal plate 26a, an insulating plate 28a, and an end plate 30a are sequentially disposed outward. Similarly, a terminal plate 26b, an insulating plate 28b, and an end plate 30b are sequentially disposed on the other end in the stacking direction of the unit cells 24 toward the outside. The end plates 30a and 30b are integrally clamped and held.

  Terminal portions 34a and 34b are provided on the side portions of the terminal plates 26a and 26b so as to protrude outward. The terminal portions 34a and 34b are electrically connected to the power source 38 via the wirings 36a and 36b. The terminal portion 34 a on the anode (anode) side is connected to the positive pole of the power source 38, while the terminal portion 34 b on the cathode (cathode) side is connected to the negative pole of the power source 38.

  As shown in FIG. 2, the unit cell 24 includes a disk-shaped electrolyte membrane / electrode structure 42, and an anode separator 44 and a cathode separator 46 that sandwich the electrolyte membrane / electrode structure 42. The anode-side separator 44 and the cathode-side separator 46 have a disk shape and are made of, for example, a carbon member or the like, or are used for corrosion protection on a steel plate, a stainless steel plate, a titanium plate, an aluminum plate, a plated steel plate, or a metal surface thereof. The metal plate that has been subjected to the above surface treatment is press-molded or cut and subjected to a corrosion-resistant surface treatment.

  The electrolyte membrane / electrode structure 42 includes, for example, a solid polymer electrolyte membrane 48 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode-side power feeder 50 and a cathode provided on both surfaces of the solid polymer electrolyte membrane 48. Side power supply body 52.

  An anode electrode catalyst layer 50 a and a cathode electrode catalyst layer 52 a are formed on both surfaces of the solid polymer electrolyte membrane 48. The anode electrode catalyst layer 50a uses, for example, a Ru (ruthenium) -based catalyst, while the cathode electrode catalyst layer 52a uses, for example, a platinum catalyst.

  The anode-side power supply body 50 and the cathode-side power supply body 52 are configured by, for example, a sintered body (porous conductor) of spherical gas-tomized titanium powder. The anode-side power feeding body 50 and the cathode-side power feeding body 52 are provided with a smooth surface portion that is etched after grinding, and the porosity is set within a range of 10% to 50%, more preferably 20% to 40%. Is done.

  The outer peripheral edge of the unit cell 24 communicates with each other in the direction of arrow A, which is the stacking direction, to supply water (pure water) 56, water generated through the reaction, oxygen generated by the reaction, and used A discharge communication hole 58 for discharging water (mixed fluid) and a hydrogen communication hole 60 for flowing hydrogen generated by the reaction are provided.

  A surface 44 a of the anode separator 44 facing the electrolyte membrane / electrode structure 42 is provided with a supply passage 62 a that communicates with the water supply communication hole 56 and a discharge passage 62 b that communicates with the discharge communication hole 58. A first flow path 64 that communicates with the supply passage 62a and the discharge passage 62b is provided on the surface 44a. The first flow path 64 is provided within a range corresponding to the surface area of the anode-side power supply body 50 and is configured by a plurality of flow path grooves, a plurality of embosses, and the like.

  A discharge passage 66 communicating with the hydrogen communication hole 60 is provided on a surface 46 a of the cathode separator 46 facing the electrolyte membrane / electrode structure 42. A second flow path 68 communicating with the discharge passage 66 is formed on the surface 46a. The second flow path 68 is provided in a range corresponding to the surface area of the cathode-side power feeder 52, and includes a plurality of flow path grooves, a plurality of embosses, and the like.

  The seal members 70a and 70b are integrated with each other around the outer peripheral ends of the anode side separator 44 and the cathode side separator 46. The seal members 70a and 70b include, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, acrylic rubber, or other seal materials, cushion materials, or packing materials. Used.

  As shown in FIG. 1, the water circulation device 16 includes a circulation pipe 72 that communicates with the water supply communication hole 56 of the water electrolysis apparatus 12, and the circulation pipe 72 includes a circulation pump 74, an ion exchanger 76, and an oxygen side gas. A liquid separator 78 is provided.

  One end of a return pipe 80 communicates with the upper part of the oxygen side gas-liquid separator 78, and the other end of the return pipe 80 communicates with a discharge communication hole 58 of the water electrolysis apparatus 12. The oxygen side gas / liquid separator 78 includes a pure water supply pipe 82 connected to the pure water supply device 14 and an oxygen exhaust pipe for discharging oxygen separated from the pure water by the oxygen side gas / liquid separator 78. 84 is connected.

  In the first embodiment, a pressure detection mechanism that detects the pressure of the mixed fluid of pure water and oxygen sent from the water electrolysis device 12 to the gas-liquid separator 78 in the return pipe 80, for example, a pressure sensor (back pressure sensor). 86 is arranged.

  One end of a high-pressure hydrogen pipe 88 is connected to the hydrogen communication hole 60 of the water electrolysis apparatus 12, and the other end of the high-pressure hydrogen pipe 88 is connected to the hydrogen-side gas-liquid separator 18. Although not shown, the high-pressure hydrogen pipe 88 is provided with a back pressure valve, and the hydrogen pressure generated in the hydrogen communication hole 60 can be maintained at a higher pressure than the oxygen side. The high-pressure hydrogen from which moisture has been removed by the hydrogen-side gas-liquid separator 18 is dehumidified by the hydrogen dehumidifier 20, and dry hydrogen is supplied to the dry hydrogen pipe 90. A drain pipe 92 is connected to the lower part of the hydrogen side gas-liquid separator 18, and a drain valve 94 is disposed in the drain pipe 92.

  The operation of the water electrolysis system 10 configured as described above will be described below.

  First, when the water electrolysis system 10 is started, pure water generated from city water is supplied to the oxygen-side gas-liquid separator 78 constituting the water circulation device 16 through the pure water supply device 14.

  In the water circulation device 16, pure water is supplied to the water supply communication hole 56 of the water electrolysis device 12 through the circulation pipe 72 under the action of the circulation pump 74. On the other hand, a voltage is applied to the terminal portions 34a and 34b of the terminal plates 26a and 26b through a power supply 38 that is electrically connected.

  Therefore, as shown in FIG. 2, in each unit cell 24, water is supplied from the water supply communication hole 56 to the first flow path 64 of the anode-side separator 44, and this water flows along the anode-side power feeder 50. Moving.

  Therefore, water is decomposed by electricity in the anode electrode catalyst layer 50a, and hydrogen ions, electrons, and oxygen are generated. Hydrogen ions generated by this anodic reaction permeate the solid polymer electrolyte membrane 48 and move to the cathode electrode catalyst layer 52a side, and combine with electrons to obtain hydrogen.

  Thereby, hydrogen flows along the second flow path 68 formed between the cathode-side separator 46 and the cathode-side power feeder 52. This hydrogen is maintained at a higher pressure than the water supply communication hole 56 and can flow out of the water electrolysis apparatus 12 through the hydrogen communication hole 60.

  On the other hand, oxygen generated by the reaction and used water flow in the first flow path 64, and these mixed fluids are discharged along the discharge communication hole 58 to the return pipe 80 of the water circulation device 16. (See FIG. 1). The used water and oxygen are introduced into the oxygen-side gas-liquid separator 78 and separated, and then the water is supplied from the circulation pipe 72 through the ion exchanger 76 via the circulation pump 74 to the water supply communication hole 56. To be introduced. Oxygen separated from the water is discharged to the outside from the oxygen exhaust pipe 84.

  The hydrogen generated in the water electrolysis apparatus 12 is sent to the hydrogen side gas-liquid separator 18 via the high-pressure hydrogen pipe 88. In the hydrogen-side gas-liquid separator 18, the water vapor contained in the hydrogen is separated from the hydrogen, while the hydrogen is dehumidified through the hydrogen dehumidifier 20 and then introduced into the dry hydrogen pipe 90.

  In this case, in the first embodiment, the return pipe 80 constituting the water circulation device 16 is located between the discharge communication hole 58 of the water electrolysis device 12 and the oxygen-side gas-liquid separator 78 and is connected to the discharge communication. A pressure sensor 86 for detecting the pressure of the mixed fluid of pure water and oxygen discharged from the hole 58 is provided.

  Based on the pressure detected by the pressure sensor 86, the controller 22 determines whether or not hydrogen leakage has occurred in the solid polymer electrolyte membrane 48 of each unit cell 24 constituting the water electrolysis device 12. .

  In the water circulation device 16, since a constant flow of circulating water is circulated through the circulation pump 74, the circulating water pressure also fluctuates with a certain width. Therefore, even if hydrogen leakage is slight, it is possible to reliably detect fluctuations in the circulating water pressure (water and oxygen pressure).

  Specifically, the detected pressure by the pressure sensor 86 increases with the passage of time as shown in FIG. 3 when hydrogen leakage occurs. Therefore, the controller 22 determines that hydrogen leakage has occurred in the solid polymer electrolyte membrane 48 when the detected value exceeds a predetermined value, for example, a reference value without hydrogen leakage.

  Further, when hydrogen leakage occurs, the pressure detected by the pressure sensor 86 increases with time. Therefore, the controller 22 may determine that hydrogen leakage has occurred in the solid polymer electrolyte membrane 48 when the detected increase rate (slope) of the pressure exceeds a predetermined value.

  Here, for example, when the pressure of hydrogen generated from the water electrolysis apparatus 12 is detected to determine whether or not there is a hydrogen leak, if the hydrogen leak amount does not reach a considerable amount, the leak is reliably ensured. It cannot be detected. On the other hand, when the hydrogen concentration contained in the oxygen discharged from the water electrolysis device 12 is detected to determine the presence or absence of hydrogen leakage, if the hydrogen leakage is unsteady, the leakage is clearly detected. Can not do it.

  Thereby, the presence or absence of hydrogen leakage from the solid polymer electrolyte membrane 48 can be easily and reliably detected by detecting the pressure of the mixed fluid of water and oxygen sent from the water electrolysis device 12 to the oxygen-side gas-liquid separator 78. It can be detected, and the effect that satisfactory water electrolysis can be performed is obtained.

  FIG. 4 is an explanatory diagram of a schematic configuration of a water electrolysis system 100 according to the second embodiment of the present invention.

  In addition, the same referential mark is attached | subjected to the component same as the water electrolysis system 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  In the water electrolysis system 100, a pressure detection mechanism that detects the pressure of oxygen separated from water by the oxygen-side gas-liquid separator 78, for example, a pressure sensor (back pressure sensor) 102 is provided in the oxygen exhaust pipe 84.

  In the second embodiment, the controller 22 determines the presence or absence of hydrogen leakage from the solid polymer electrolyte membrane 48 based on the change in oxygen pressure detected via the pressure sensor 102. Since the pressure (back pressure) of the oxygen discharged from the oxygen-side gas-liquid separator 78 is smaller than the fluctuation range of the circulating water pressure, the fluctuation of the oxygen pressure is surely ensured even if hydrogen leakage is slight. It becomes possible to detect.

  Specifically, when hydrogen leaks in the solid polymer electrolyte membrane 48, the oxygen pressure detected by the pressure sensor 102 increases with time as shown in FIG. Yes. Therefore, the controller 22 determines that hydrogen leakage has occurred in the solid polymer electrolyte membrane 48 when the detected oxygen pressure exceeds a predetermined reference value without hydrogen leakage.

  The controller 22 may determine that hydrogen leakage has occurred in the solid polymer electrolyte membrane 48 when the detected increase rate of the oxygen pressure exceeds a predetermined value.

  Thus, by detecting the pressure of oxygen separated from water and discharged from the oxygen-side gas-liquid separator 78, it is possible to easily and reliably detect the presence or absence of hydrogen leakage from the solid polymer electrolyte membrane 48. it can. For this reason, in 2nd Embodiment, the effect similar to said 1st Embodiment is acquired, such as enabling favorable water electrolysis processing to be performed.

  FIG. 6 is a schematic configuration explanatory diagram of a water electrolysis system 120 according to the third embodiment of the present invention.

  In the water electrolysis system 120, a pressure sensor 86 for detecting the pressure of a mixed fluid of water and oxygen sent from the water electrolysis device 12 to the oxygen side gas-liquid separator 78 to the return pipe 80, and the oxygen side separated from the water And a pressure sensor 102 that detects the pressure of oxygen discharged from the gas-liquid separator 78.

  The controller 22 detects the solid polymer electrolyte when at least one of the detected pressures exceeds a predetermined value based on the detected pressures sent from the pressure sensors 86 and 102 or when the rate of increase in pressure exceeds a predetermined value. It is determined that hydrogen leaks from the membrane 48. Therefore, in the third embodiment, the same effect as in the first and second embodiments can be obtained.

  In the first to third embodiments, when the controller 22 determines that hydrogen leakage from the solid polymer electrolyte membrane 48 has occurred, the depressurization of the high-pressure hydrogen side of the water electrolysis device 12 is performed. Corresponding treatment is performed by performing treatment or stopping the electrolytic treatment.

DESCRIPTION OF SYMBOLS 10, 100, 120 ... Water electrolysis system 12 ... Water electrolysis apparatus 14 ... Pure water supply apparatus 16 ... Water circulation apparatus 18 ... Hydrogen side gas-liquid separator 20 ... Hydrogen dehumidifier 22 ... Controller 24 ... Unit cell 38 ... Power supply 42 ... Electrolyte Membrane / electrode structure 44 ... anode side separator 46 ... cathode side separator 48 ... solid polymer electrolyte membrane 50 ... anode side power supply body 52 ... cathode side power supply body 56 ... water supply communication hole 58 ... discharge communication hole 60 ... hydrogen communication hole 64, 68 ... flow path 72 ... circulation pipe 78 ... oxygen side gas-liquid separator 80 ... return pipe 82 ... pure water supply pipe 84 ... oxygen exhaust pipe 86 ... pressure sensor 88 ... high pressure hydrogen pipe 102 ... pressure sensor

Claims (6)

A water electrolysis device provided with power supply bodies on both sides of the electrolyte membrane, electrolyzes water to generate oxygen in one power supply body, and generates hydrogen in the other power supply body,
A water circulation device that circulates and supplies the excess water discharged from the water electrolysis device to the water electrolysis device;
A water electrolysis system comprising:
The water circulation device includes a gas-liquid separation mechanism that separates the water and oxygen mixed fluid discharged from the water electrolysis device into the water and oxygen.
A pressure detection mechanism for detecting the pressure of the mixed fluid of water and oxygen sent from the water electrolysis device to the gas-liquid separation mechanism;
Based on the pressure detected by the pressure detection mechanism, a controller that determines the presence or absence of leakage of the hydrogen from the electrolyte membrane;
A water electrolysis system comprising:   2. The water electrolysis system according to claim 1, wherein the control unit determines that the hydrogen leaks when the detected pressure exceeds a predetermined value. 3.   3. The water electrolysis system according to claim 1, wherein the control unit determines that the hydrogen leaks when the detected rate of increase in pressure exceeds a predetermined value. 4. system. A water electrolysis device provided with power supply bodies on both sides of the electrolyte membrane, electrolyzes water to generate oxygen in one power supply body, and generates hydrogen in the other power supply body,
A water circulation device that circulates and supplies the excess water discharged from the water electrolysis device to the water electrolysis device;
A water electrolysis system comprising:
The water circulation device includes a gas-liquid separation mechanism that separates the water and oxygen mixed fluid discharged from the water electrolysis device into the water and oxygen.
A pressure detection mechanism that detects the pressure of the oxygen separated from the water and discharged from the gas-liquid separation mechanism;
Based on the pressure detected by the pressure detection mechanism, a controller that determines the presence or absence of leakage of the hydrogen from the electrolyte membrane;
A water electrolysis system comprising:   5. The water electrolysis system according to claim 4, wherein the control unit determines that the hydrogen is leaked when the detected pressure exceeds a predetermined value. 6.   6. The water electrolysis system according to claim 4, wherein the control unit determines that the hydrogen leak is present when the detected rate of increase in pressure exceeds a predetermined value. system.

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