WO2024106099A1 - 水電解装置及び水電解装置の運転方法 - Google Patents

水電解装置及び水電解装置の運転方法 Download PDF

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Publication number
WO2024106099A1
WO2024106099A1 PCT/JP2023/037256 JP2023037256W WO2024106099A1 WO 2024106099 A1 WO2024106099 A1 WO 2024106099A1 JP 2023037256 W JP2023037256 W JP 2023037256W WO 2024106099 A1 WO2024106099 A1 WO 2024106099A1
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Prior art keywords
water electrolysis
pressure
regulating valve
cathode
pressure regulating
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PCT/JP2023/037256
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English (en)
French (fr)
Japanese (ja)
Inventor
雄太 彦根
貴之 中植
浩一郎 朝澤
幸宗 可児
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to JP2024558709A priority Critical patent/JPWO2024106099A1/ja
Priority to EP23889870.4A priority patent/EP4621107A1/en
Publication of WO2024106099A1 publication Critical patent/WO2024106099A1/ja
Priority to US19/185,317 priority patent/US20250250703A1/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00—Diaphragms; Spacing elements
    • C25B13/04—Diaphragms; Spacing elements characterised by the material
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/05—Pressure cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/70—Assemblies comprising two or more cells
    • C25B9/73—Assemblies comprising two or more cells of the filter-press type
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

  • This disclosure relates to a water electrolysis device and a method for operating the water electrolysis device.
  • a system for storing hydrogen energy for energy storage is being considered.
  • surplus electricity is used to produce hydrogen, and the electricity is stored as hydrogen energy.
  • the stored hydrogen energy is used to generate electricity and supply power.
  • Water electrolysis, or water electrolysis is a widely known method for generating hydrogen using electricity. In water electrolysis, hydrogen and oxygen are generated by an electrochemical reaction.
  • Patent Document 1 describes an electrolysis device comprising an anode chamber, a cathode chamber, a diaphragm, an anode side circulation line, and a cathode side circulation line.
  • the anode chamber accommodates an anode and generates anode gas.
  • the cathode chamber accommodates a cathode and generates hydrogen gas.
  • the diaphragm separates the anode chamber from the cathode chamber.
  • the anode side circulation line discharges the electrolyte from the anode chamber and returns it to the anode chamber.
  • the anode side circulation line is equipped with an anode side gas-liquid separation means.
  • the anode side gas-liquid separation means separates the electrolyte transported from the anode chamber and the anode gas.
  • the cathode side circulation line is equipped with a cathode side gas-liquid separation means.
  • the cathode side gas-liquid separation means separates the electrolyte transported from the cathode chamber and the hydrogen gas.
  • a circulation tank which is a sealed container, is provided on the way of the anode side supply line and the cathode side supply line, and the electrolyte separated by the anode side gas-liquid separation means and the cathode side gas-liquid separation means is transported to the circulation tank.
  • the electrolyte transported to the circulation tank contains dissolved oxygen gas and dissolved hydrogen gas.
  • the dissolved oxygen gas and dissolved hydrogen gas in the electrolyte exceeds the saturated dissolution amount due to the operating conditions of the electrolysis device, the dissolved oxygen gas and dissolved hydrogen gas become gas. This gas accumulates in the gas phase region at the top of the circulation tank. While only a small amount of hydrogen gas is released into the gas phase region, a large amount of oxygen gas is delivered to the gas phase region. Therefore, the hydrogen gas is diluted in the gas phase region, and the hydrogen gas concentration is reliably below the lower explosion limit.
  • the present disclosure provides a water electrolysis device that is more advantageous from the standpoint of safety than conventional devices.
  • a water electrolysis apparatus comprising: a water electrolysis cell including a diaphragm or an electrolyte membrane, an anode provided in one space separated by the diaphragm or on one main surface of the electrolyte membrane, and a cathode provided in the other space separated by the diaphragm or on the other main surface of the electrolyte membrane; a voltage applicator that applies a voltage between the anode and the cathode; a pressure regulating valve for regulating the pressure of the hydrogen-containing gas discharged from the cathode; a controller that controls the voltage applicator to increase the current flowing through the water electrolysis cell at the time of start-up of the water electrolysis device, and then controls the pressure regulating valve to increase the set pressure of the pressure regulating valve.
  • a water electrolysis device is provided.
  • This disclosure provides a water electrolysis device that is more advantageous in terms of safety than conventional devices.
  • FIG. 1 is a diagram illustrating a water electrolysis device according to an embodiment.
  • FIG. 2 is a flowchart showing an example of a method for operating the water electrolysis apparatus shown in FIG.
  • FIG. 3 is a diagram illustrating a schematic diagram of another example of a water electrolysis device according to an embodiment.
  • FIG. 4 is a diagram illustrating a schematic diagram of still another example of a water electrolysis device according to an embodiment.
  • FIG. 5 is a graph showing the relationship between the pressure at the cathode and the current density in the water electrolysis cell, and the hydrogen concentration.
  • the current density in the water electrolysis cell is likely to be low and the amount of oxygen gas produced at the anode is small, so that the hydrogen concentration is likely to be relatively high when the water electrolysis device is started up, and the hydrogen gas concentration near the anode may exceed the lower explosion limit.
  • the inventors therefore conducted extensive research to address the above-mentioned issues.
  • the inventors discovered that the hydrogen gas concentration can be kept below the lower explosion limit by adjusting the current flowing through the water electrolysis cell and the pressure of the hydrogen-containing gas discharged from the cathode when the water electrolysis device is started up. Based on this new knowledge, the inventors have completed the water electrolysis device disclosed herein.
  • FIG. 1 is a schematic diagram of a water electrolysis device according to an embodiment.
  • the water electrolysis device 100 includes a water electrolysis cell 10, a voltage applicator 20, a pressure regulating valve 30, and a controller 40.
  • the water electrolysis cell 10 includes an electrolyte membrane 11, an anode 12, and a cathode 13.
  • the anode 12 is provided on a first main surface, which is one of the main surfaces of the electrolyte membrane 11.
  • the cathode 13 is provided on a second main surface, which is the other main surface of the electrolyte membrane 11.
  • the voltage applicator 20 applies a voltage between the anode 12 and the cathode 13.
  • the controller 40 controls the voltage applicator 20 to increase the current flowing through the water electrolysis cell 10, and then controls the pressure regulating valve 30 to increase the set pressure of the pressure regulating valve 30.
  • the voltage applicator 20 is connected to the controller 40 so as to receive a control signal from the controller 40.
  • the pressure regulating valve 30 is connected to the controller 40 so as to receive a control signal from the controller 40.
  • the water electrolysis device 100 includes, for example, an anode supply path 52a, an anode discharge path 52b, and a cathode discharge path 53.
  • the anode supply path 52a and the anode discharge path 52b are connected to the water electrolysis cell 10 on the anode 12 side.
  • the cathode discharge path 53 is connected to the water electrolysis cell 10 on the cathode 13 side.
  • an electrolyte is supplied to the water electrolysis cell 10 through the anode supply channel 52a.
  • the electrolyte may be water or an alkaline solution.
  • a voltage is applied between the anode 12 and the cathode 13, causing electrolysis of water.
  • oxygen gas is generated in the anode 12, and hydrogen gas is generated in the cathode 13.
  • the oxygen gas generated in the anode 12 is discharged to the outside of the water electrolysis cell 10 through the anode discharge channel 52b.
  • the hydrogen gas generated in the cathode 13 is discharged to the outside of the water electrolysis cell 10 through the cathode discharge channel 53.
  • the electrolyte supplied to the water electrolysis cell 10 is discharged to the outside of the water electrolysis cell 10 through the anode discharge channel 52b.
  • a gas-liquid separator (not shown) is disposed in the anode discharge channel 52b, and the electrolyte and oxygen gas are separated in the gas-liquid separator.
  • the water electrolysis device 100 is, for example, a water electrolysis device with a one-side water supply system. Therefore, the water electrolysis device 100 does not have a supply path for supplying an electrolyte to the cathode 13 side of the water electrolysis cell 10. With this configuration, the water electrolysis device 100 has a simple structure, and the manufacturing costs and running costs of the water electrolysis device 100 tend to be low. On the other hand, the water electrolysis device 100 may be provided with a supply path for supplying an electrolyte to the cathode 13 side of the water electrolysis cell 10, or may be configured as a water electrolysis device with a two-side water supply system.
  • the electrolyte membrane 11 is not limited to a specific membrane as long as it has ion conductivity.
  • the electrolyte membrane 11 may be an anion exchange membrane (AEM) or a proton exchange membrane (PEM).
  • AEM anion exchange membrane
  • PEM proton exchange membrane
  • the water electrolysis device 100 may be an AEM type water electrolysis device or a PEM type water electrolysis device.
  • the voltage applicator 20 may, for example, apply a DC voltage between the anode 12 and the cathode 13.
  • the power supply connected to the voltage applicator 20 is not limited to a specific type of power supply.
  • the voltage applicator 20 may be connected to a DC power supply.
  • the voltage applicator 20 includes, for example, a DC/DC converter.
  • the voltage applicator 20 may be connected to an AC power supply.
  • the voltage applicator 20 includes, for example, an AC/DC converter.
  • the pressure regulating valve 30 is disposed, for example, in the cathode exhaust passage 53.
  • the pressure regulating valve 30 regulates the pressure of the hydrogen-containing gas discharged from the cathode 13.
  • the pressure regulating valve 30 is not limited to a specific valve.
  • the pressure regulating valve 30 is, for example, a known back pressure valve.
  • the pressure of the hydrogen-containing gas discharged from the cathode 13 is the pressure of the hydrogen-containing gas in the space in contact with the cathode electrode in the cathode 13.
  • the controller 40 is not limited to a specific configuration as long as it can control the voltage applicator 20 and the pressure regulating valve 30.
  • the controller 40 includes, for example, an arithmetic circuit and a memory circuit, and the memory circuit stores a program for controlling the voltage applicator 20 and the pressure regulating valve 30 so that the program can be executed by the arithmetic circuit.
  • the following operations can be performed, for example, by a program read from the memory circuit of the controller 40 being executed in the arithmetic circuit. It is not essential that the following operations are performed only by the controller 40, and some of the operations may be performed by an operator.
  • the operation of the water electrolysis device 100 will be described using an example in which the electrolyte membrane 11 is an anion exchange membrane and the electrolyte is an aqueous potassium hydroxide solution.
  • the potassium hydroxide aqueous solution is supplied to the anode 12 of the water electrolysis cell 10 through the anode supply passage 52a, and a voltage is applied between the anode 12 and the cathode 13 by the voltage applicator 20.
  • an oxidation reaction of hydroxide ions proceeds in the anode 12, and oxygen and electrons are generated, as shown in the following formula (1).
  • the oxygen is discharged to the outside of the water electrolysis cell 10 through the anode discharge passage 52b together with the potassium hydroxide aqueous solution.
  • the electrons are moved to the cathode 13 by the voltage applicator 20.
  • a reduction reaction of water proceeds in the cathode 13, and hydrogen and hydroxide ions are generated.
  • Hydrogen generated at the cathode 13 by the electrochemical reaction is discharged to the outside of the water electrolysis cell 10 through the cathode exhaust channel 53.
  • the pressure of the hydrogen-containing gas discharged from the cathode 13 is adjusted by the pressure regulating valve 30. This makes it possible, for example, to increase the pressure of the hydrogen-containing gas discharged from the cathode 13 above atmospheric pressure.
  • the controller 40 may, for example, control the pressure regulating valve 30 to adjust the pressure of the hydrogen-containing gas discharged from the cathode 13 to 3 MPaG or more. This makes it possible to supply high-pressure hydrogen-containing gas to the outside of the water electrolysis cell 10.
  • the upper limit of the pressure of the hydrogen-containing gas discharged from the cathode 13 is not limited to a specific value.
  • the pressure of the hydrogen-containing gas discharged from the cathode 13 is, for example, 20 MPaG or less. In this case, the manufacturing cost of the water electrolysis device 100 is unlikely to be high due to the pressure resistance required of the water electrolysis cell 10.
  • the pressure of the hydrogen-containing gas discharged from the cathode 13 increases as a result of the control of the pressure regulating valve 30, the amount of hydrogen permeating the electrolyte membrane 11 from the cathode 13 to the anode 12 increases, and the concentration of hydrogen gas near the anode 12 tends to become high. In particular, when the current density in the water electrolysis cell is low, the amount of oxygen generated at the anode 12 is small. On the other hand, the amount of hydrogen permeating the electrolyte membrane 11 from the cathode 13 to the anode 12 is proportional to the pressure difference between the cathode 13 and the anode 12.
  • the controller 40 controls the voltage applicator 20 to increase the current flowing through the water electrolysis cell 10, and then controls the pressure regulating valve 30 to increase the set pressure of the pressure regulating valve 30. As a result, when the current density in the water electrolysis cell is low, the pressure of the hydrogen-containing gas discharged from the cathode 13 is kept low.
  • the pressure regulating valve 30 is controlled so that the set pressure of the pressure regulating valve 30 is increased before or simultaneously with the current flowing through the water electrolysis cell 10, the possibility that the concentration of hydrogen gas in the anode 12 will exceed the lower explosion limit is reduced.
  • the current flowing through the water electrolysis cell 10 is increased by controlling the voltage applicator 20, the amount of oxygen generated in the anode 12 increases. Therefore, even if the pressure of the hydrogen-containing gas discharged from the cathode 13 is increased thereafter, the increase in the amount of hydrogen permeating the electrolyte membrane 11 from the cathode 13 to the anode 12 reduces the possibility that the concentration of hydrogen gas in the anode 12 will exceed the lower explosion limit.
  • the controller 30 increases the set pressure of the pressure regulating valve 30 so that it is equal to or lower than the upper limit of the set pressure of the pressure regulating valve 30 set for the current value of the water electrolysis cell 10. This reduces the possibility that the concentration of hydrogen gas in the anode 12 exceeds the lower explosion limit due to an increase in the amount of hydrogen permeating through the electrolyte membrane 11 from the cathode 13 to the anode 12.
  • the upper limit of the set pressure of the pressure regulating valve 30 is set so that the concentration of hydrogen gas in the anode 12 does not exceed the lower explosion limit when the current value of the water electrolysis cell 10 is a predetermined value.
  • the upper limit of the set pressure is appropriately set as the set pressure of the pressure control valve 30 that realizes an upper limit pressure equal to or lower than the cathode pressure at the boundary between the white region and the gray region at a predetermined current density shown in FIG. 5.
  • the upper limit of the set pressure of the pressure regulating valve 30 may be directly associated with the current value of the water electrolysis cell 10, or the upper limit of the set pressure of the pressure regulating valve 30 may be directly associated with a parameter that indirectly indicates the current value of the water electrolysis cell 10.
  • An example of such a parameter is the voltage value applied to the water electrolysis cell 10.
  • the controller 30 may control the pressure regulating valve 30 to increase the set pressure of the pressure regulating valve 30. This reduces the possibility that the concentration of hydrogen gas at the anode 12 will exceed the lower explosion limit due to an increase in the amount of hydrogen permeating through the electrolyte membrane 11 from the cathode 13 to the anode 12.
  • the controller 30 may control the pressure regulating valve 30 to increase the set pressure of the pressure regulating valve 30. This reduces the possibility that the concentration of hydrogen gas at the anode 12 will exceed the lower explosion limit due to an increase in the amount of hydrogen permeating through the electrolyte membrane 11 from the cathode 13 to the anode 12.
  • the first set pressure which is the set pressure before the set pressure of the pressure regulating valve 30 is increased, is smaller than, for example, the second set pressure, which is the set pressure of the pressure regulating valve when the current value of the water electrolysis cell 10 is the target current value during water electrolysis operation of the water electrolysis device 100. This reduces the possibility that the hydrogen gas concentration near the anode 12 will become extremely high.
  • the first set pressure which is the set pressure before the set pressure of the pressure regulating valve 30 is increased, may be, for example, atmospheric pressure. This can further reduce the possibility that the hydrogen gas concentration near the anode 12 will become extremely high.
  • FIG. 2 is a flowchart showing an example of a method for operating the water electrolysis system 100.
  • the water electrolysis system 100 is operated, for example, according to a method including the following (I) and (II).
  • a voltage is applied between the anode 12 and the cathode 13 that are provided on either side of the electrolyte membrane 11 to cause a water electrolysis reaction in the water electrolysis cell 10 .
  • II When the water electrolysis system 100 is started up, the current flowing through the water electrolysis cell 10 is increased, and then the pressure regulating valve 30 is controlled to increase the set pressure of the pressure regulating valve 30 .
  • the controller 40 controls the pressure regulating valve 30 so that the pressure regulating valve 30 is in a fully open state.
  • the pressure regulating valve 30 is controlled so that the pressure applied to the valve body by the drive unit of the pressure regulating valve 30 (the set pressure of the pressure regulating valve 30) is minimized.
  • the pressure control valve 30 may be controlled so that the set pressure of the pressure regulating valve 30 is atmospheric pressure (0 PaG). At this time, if the pressure regulating valve 30 is a back pressure valve, the pressure regulating valve 30 is controlled so that the pressure applied to the diaphragm is 0 PaG.
  • the controller 40 may, for example, obtain a pressure detection signal from a sensor 32 for detecting the pressure on the primary side of the pressure regulating valve 30, and may determine whether the pressure regulating valve 30 is in a fully open state based on the pressure detection signal. If this determination is positive, the process of step S1 may be skipped, and if this determination is negative, the process of step S1 may be performed.
  • the pressure regulating valve 30 may be controlled so that the pressure regulating valve 30 is fully open when the water electrolysis device 100 is stopped. In this case, step S1 may be omitted, and the determination of whether the pressure regulating valve 30 is fully open may be omitted.
  • step S2 the controller 40 controls the voltage applicator 20 to increase the current flowing through the water electrolysis cell 10.
  • the voltage applicator 20 is controlled so that a voltage corresponding to the target value Ti of the current flowing through the water electrolysis cell 10 is applied between the anode 12 and the cathode 13.
  • step S3 the controller 40 acquires a detection signal of the current Ic flowing through the water electrolysis cell 10 from the voltage applicator 20, and determines whether the current Ic has reached the target value Ti.
  • This target value Ti is set, for example, based on the target value Tp of the pressure of the hydrogen-containing gas discharged from the cathode 13 of the water electrolysis device 100 and the amount of cross leakage of hydrogen gas from the electrolyte membrane 11 at a pressure corresponding to the target value Tp.
  • Tp the target value of the pressure of the hydrogen-containing gas discharged from the cathode 13 of the water electrolysis device 100 and the amount of cross leakage of hydrogen gas from the electrolyte membrane 11 at a pressure corresponding to the target value Tp.
  • the target value Ti is set so that the concentration of hydrogen gas in the anode 12 is less than the lower explosion limit.
  • step S3 The determination in step S3 is repeated at a predetermined interval until the determination is affirmative.
  • the pressure regulating valve 30 is kept fully open in steps S2 and S3. Therefore, when the current Ic increases in steps S2 and S3, the pressure in the cathode 13 is kept at atmospheric pressure (0 PaG).
  • step S3 the process proceeds to step S4, where the controller 40 controls the pressure regulating valve 30 to increase the set pressure of the pressure regulating valve 30. This increases the pressure of the hydrogen-containing gas discharged from the cathode 13.
  • the controller 40 controls the back pressure valve to increase the pressure applied to the diaphragm.
  • step S5 the controller 40 acquires a pressure detection signal from the sensor 32 for detecting the pressure Pco of the hydrogen-containing gas discharged from the cathode 13, for example, and determines whether the pressure Pco has reached the target value Tp.
  • the determination in step S5 is repeated at a predetermined interval until the determination is affirmative. If the determination in step S5 is affirmative, the series of processes ends and the start-up of the water electrolysis device 100 is completed. Thereafter, the water electrolysis device 100 is operated in accordance with the target value Ti of the current flowing through the water electrolysis cell 10 and the target value Tp of the pressure of the hydrogen-containing gas discharged from the cathode 13.
  • the water electrolysis device 100 may be configured such that the cathode 13 is connected to the tank 55.
  • FIG. 3 is a diagram showing another example of the water electrolysis device according to the embodiment.
  • the cathode 13 is connected to the inlet of the tank 55, and the pressure regulating valve 30 is disposed on the outlet side of the tank 55.
  • the tank 55 is disposed between the cathode 13 and the pressure regulating valve 30.
  • the tank 55 is connected to a communication passage 54 that can communicate with the atmosphere, and an opening/closing valve 36 is disposed in the communication passage 54.
  • step S4 when the pressure regulating valve 30 is controlled to increase the pressure of the hydrogen-containing gas discharged from the cathode 13, the opening/closing valve 36 is controlled to close.
  • FIG. 4 is a schematic diagram of yet another example of a water electrolysis device according to an embodiment.
  • the water electrolysis cell 10a is configured similarly to the water electrolysis cell 10, except for parts that will be specifically described. Components of the water electrolysis cell 10a that are the same as or correspond to those of the water electrolysis cell 10 are given the same reference numerals, and detailed descriptions will be omitted.
  • the above description of the water electrolysis cell 10 also applies to the water electrolysis cell 10a, unless there is a technical contradiction.
  • the water electrolysis cell 10a includes a diaphragm 11a, an anode 12, and a cathode 13.
  • the anode 12 is provided in a first space, which is one of the spaces separated by the diaphragm 11a.
  • the cathode 13 is provided in a second space, which is the other space separated by the diaphragm 11a.
  • the controller 40 controls the voltage applicator 20 and the pressure regulating valve 30 as described above, thereby reducing the possibility that the concentration of hydrogen gas in the anode 12 will exceed the lower explosion limit.
  • the diaphragm 11a is, for example, a diaphragm for alkaline water electrolysis.
  • the diaphragm 11a is, for example, a sheet-like porous membrane.
  • the diaphragm 11a has a thickness of, for example, 100 ⁇ m to 500 ⁇ m and has holes that serve as passages for ions or electrolyte.
  • the material of the diaphragm 11a is not limited to a specific material. Examples of the material of the diaphragm 11a are asbestos, polymer-reinforced asbestos, potassium titanate bound with polytetrafluoroethylene (PTFE), zirconia bound with PTFE, and antimonic acid and antimony oxide bound with polysulfone. Other examples of the material of the diaphragm 11a are sintered nickel, nickel coated with ceramics and nickel oxide, and polysulfone.
  • the diaphragm 11a may be Zirfon Perl UTP 500 manufactured by AGFA.
  • a water electrolysis apparatus comprising: a water electrolysis cell including a diaphragm or an electrolyte membrane, an anode provided in one space separated by the diaphragm or on one main surface of the electrolyte membrane, and a cathode provided in the other space separated by the diaphragm or on the other main surface of the electrolyte membrane; a voltage applicator that applies a voltage between the anode and the cathode; a pressure regulating valve for regulating the pressure of the hydrogen-containing gas discharged from the cathode; a controller that controls the voltage applicator to increase the current flowing through the water electrolysis cell at the time of start-up of the water electrolysis device, and then controls the pressure regulating valve to increase the set pressure of the pressure regulating valve.
  • Water electrolysis device Water electrolysis device.
  • the controller controls the pressure regulating valve to make the pressure of the hydrogen-containing gas discharged from the cathode equal to or higher than 3 MPaG.
  • the controller increases the set pressure of the pressure regulating valve so that the set pressure of the pressure regulating valve is equal to or lower than an upper limit of the set pressure of the pressure regulating valve, which is set for a value of the current flowing through the water electrolysis cell.
  • the controller controls the pressure regulating valve to increase the set pressure of the pressure regulating valve when a value of the current flowing through the water electrolysis cell reaches a predetermined current value that is smaller than a target current value during water electrolysis operation of the water electrolysis device.
  • the water electrolysis device according to any one of claims 1 to 3.
  • a first set pressure which is the set pressure before the set pressure of the pressure regulating valve is increased, is lower than a second set pressure, which is the set pressure of the pressure regulating valve when a value of the current flowing through the water electrolysis cell is a target current value during water electrolysis operation of the water electrolysis device.
  • the water electrolysis device according to any one of claims 1 to 5.
  • the first set pressure is 0 PaG.
  • the electrolyte membrane is an anion exchange membrane.
  • the water electrolysis device according to any one of claims 1 to 7.
  • the electrolyte membrane is a proton exchange membrane.
  • the water electrolysis device according to any one of claims 1 to 7.
  • a method for operating a water electrolysis apparatus including a water electrolysis cell including an anode and a cathode sandwiching a diaphragm or an electrolyte membrane, and a pressure regulating valve for regulating a pressure of a hydrogen-containing gas discharged from the cathode, comprising: applying a voltage between the anode and the cathode to cause a water electrolysis reaction in the water electrolysis cell; and increasing a current flowing through the water electrolysis cell at the start-up of the water electrolysis apparatus, and then controlling the pressure regulating valve to increase a set pressure of the pressure regulating valve.
  • a method for operating a water electrolysis device comprising: applying a voltage between the anode and the cathode to cause a water electrolysis reaction in the water electrolysis cell; and increasing a current flowing through the water electrolysis cell at the start-up of the water electrolysis apparatus, and then controlling the pressure regulating valve to increase a set pressure of the pressure regulating valve.
  • the relationship between the pressure at the cathode 13 and the current density and hydrogen concentration in the water electrolysis cell 10 can be clarified by measuring the physical properties of the electrolyte membrane 11.
  • the relationship between the pressure at the cathode and the current density and hydrogen concentration in the water electrolysis cell when using Takahata Precision's electrolyte membrane QPAF-4 was investigated as follows.
  • the thickness of the electrolyte membrane QPAF-4 was 30 ⁇ m.
  • FIG. 5 is a graph showing the relationship between the pressure at the cathode 13 and the current density and hydrogen concentration in the water electrolysis cell 10 when the water electrolysis device 100 is manufactured using the electrolyte membrane QPAF-4 as the electrolyte membrane 11.
  • the gray area indicates the condition where the hydrogen concentration is equal to or greater than the predetermined reference value
  • the other areas indicate the condition where the hydrogen concentration is less than the predetermined reference value.
  • the method for creating the graph in FIG. 5 is explained below. Note that the graph in FIG. 5 may change depending on the physical properties of the electrolyte membrane and the experimental conditions, but the method for creating this graph is also applicable to other electrolyte membranes and other experimental conditions. Note that the relationship between the pressure at the cathode and the current density and hydrogen concentration in the water electrolysis cell in this disclosure is not limited to the relationship shown in FIG. 5.
  • the hydrogen gas permeability coefficient of the electrolyte membrane QPAF-4 at 60°C was measured in accordance with the differential pressure method specified in Japanese Industrial Standards (JIS) K7126-1.
  • nH the amount of hydrogen gas permeating the electrolyte membrane from the cathode to the anode per unit time and unit area
  • nH the amount of hydrogen gas permeating the electrolyte membrane from the cathode to the anode per unit time and unit area
  • nH the amount of hydrogen gas permeating the electrolyte membrane from the cathode to the anode per unit time and unit area
  • nH the amount of hydrogen gas permeating the electrolyte membrane from the cathode to the anode per unit time and unit area
  • PC is the pressure at the cathode [Pa]
  • nO The amount of oxygen produced per unit time and unit area at the anode of this water electrolysis cell, nO [mol/( cm2 x s)], is given by the following formula (5).
  • I is the current density in the water electrolysis cell [C/( cm2 x s)].
  • the current density I is determined according to the electrode area.
  • F is the Faraday constant [C/mol].
  • nO I/(4 ⁇ F) (5)
  • the hydrogen concentration cH [vol %] at the anode is expressed by the following formula (6).
  • cH nH / (nH + nO) ⁇ 100 (6)
  • LEL is the hydrogen explosion lower limit concentration [volume %]
  • sf is the safety factor [-].
  • the safety factor sf is 5
  • the hydrogen concentration cH at the anode calculated by formula (6) was compared with the hydrogen explosion risk standard concentration clim calculated by formula (7) to determine the possibility of a hydrogen explosion risk. If the condition of hydrogen concentration cH ⁇ hydrogen explosion risk standard concentration clim is satisfied, it can be determined that there is no risk of a hydrogen explosion and that it is safe. If the condition of hydrogen concentration cH ⁇ hydrogen explosion risk standard concentration clim is satisfied, it can be determined that there is a risk of a hydrogen explosion and that it is dangerous.
  • the risk of hydrogen explosion can be avoided by operating the water electrolysis device under conditions determined to be free of risk of hydrogen explosion in the graph shown in FIG. 5.
  • the target value of the pressure of the hydrogen-containing gas discharged from the cathode is 3 MPaG
  • the current density of the water electrolysis cell is increased from 0 to 1.6 Acm ⁇ 2 or more when the water electrolysis device is started up.
  • the pressure regulating valve is kept in a fully open state. After the current density reaches 1.6 Acm ⁇ 2 or more, the pressure regulating valve is controlled so that the pressure of the hydrogen-containing gas discharged from the cathode approaches the target value, and it can be seen that the water electrolysis device can be started up under conditions free of risk of hydrogen explosion.
  • the voltage applicator and the pressure regulating valve may be controlled so that the current density and the pressure of the hydrogen-containing gas increase stepwise.
  • the water electrolysis device disclosed herein can be started up in a state where the risk of hydrogen explosion is reduced.

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PCT/JP2023/037256 2022-11-16 2023-10-13 水電解装置及び水電解装置の運転方法 Ceased WO2024106099A1 (ja)

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Citations (6)

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Publication number Priority date Publication date Assignee Title
JP2012111981A (ja) * 2010-11-19 2012-06-14 Takasago Thermal Eng Co Ltd 水素製造方法及び水素製造システム
JP2012167331A (ja) * 2011-02-15 2012-09-06 Honda Motor Co Ltd 差圧式水電解装置の運転方法
JP2014062311A (ja) * 2012-09-24 2014-04-10 Honda Motor Co Ltd 高圧水電解システム及びその起動方法
WO2017030153A1 (ja) 2015-08-20 2017-02-23 デノラ・ペルメレック株式会社 電解装置及び電解方法
JP2021181605A (ja) * 2020-05-20 2021-11-25 株式会社豊田中央研究所 水電解システム、および水電解システムの制御方法
JP7158529B1 (ja) * 2021-05-06 2022-10-21 本田技研工業株式会社 水電解システム及び水電解装置の起動方法

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Publication number Priority date Publication date Assignee Title
JP2012111981A (ja) * 2010-11-19 2012-06-14 Takasago Thermal Eng Co Ltd 水素製造方法及び水素製造システム
JP2012167331A (ja) * 2011-02-15 2012-09-06 Honda Motor Co Ltd 差圧式水電解装置の運転方法
JP2014062311A (ja) * 2012-09-24 2014-04-10 Honda Motor Co Ltd 高圧水電解システム及びその起動方法
WO2017030153A1 (ja) 2015-08-20 2017-02-23 デノラ・ペルメレック株式会社 電解装置及び電解方法
JP2021181605A (ja) * 2020-05-20 2021-11-25 株式会社豊田中央研究所 水電解システム、および水電解システムの制御方法
JP7158529B1 (ja) * 2021-05-06 2022-10-21 本田技研工業株式会社 水電解システム及び水電解装置の起動方法

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Title
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