Electrolysis device

Abstract

An electrolysis device according to the present disclosure comprises an electrolytic cell, an electrolyte supply unit, and an ion concentration control unit. The electrolytic cell has a positive electrode chamber, a negative electrode chamber, and an ion exchange membrane disposed between the positive electrode chamber and the negative electrode chamber. The electrolyte supply unit has at least one tank for accommodating an electrolyte, circulates, as a first electrolyte, a portion of the electrolyte between the at least one tank and the positive electrode chamber, and circulates, as a second electrolyte, another portion of the electrolyte between the at least one tank and the negative electrode chamber. The ion concentration control unit supplies a controlling liquid for controlling hydrogen ion concentration to the electrolyte supply unit.

Description

[Technical field]

[0001] The present disclosure relates to electrolysis devices. This application claims priority to Japanese Patent Application No. 2022-119271, filed on July 27, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Patent Document 1 discloses a carbon dioxide electrolysis device including: an electrolysis cell having a cathode that reduces a first substance containing carbon dioxide to produce a first product containing a carbon compound; and an anode that oxidizes a second substance containing water or hydroxide ions to produce a second product containing oxygen; a sensor that detects an ion concentration in a liquid discharged from at least one of an anode flow path and a cathode flow path; a refreshing agent supply unit that is capable of supplying a gaseous substance to at least one of the anode flow path and the cathode flow path; and a control unit that stops the supply of carbon dioxide and electrolytic solution to the electrolysis cell and controls the operation of the refreshing agent supply unit to supply the gaseous substance to at least one of the anode flow path and the cathode flow path based on data acquired by the sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-045515 A Summary of the Invention [Problem to be solved by the invention]

[0004] In electrolysis devices such as AEM (Anion Exchange Membrane) type, ions move between the anode chamber and the cathode chamber as electrolysis proceeds, causing changes in the hydrogen ion concentration (pH) in the anode chamber and the cathode chamber. When the hydrogen ion concentration (pH) changes, the electrical conductivity of the electrolyte changes, which can lead to a decrease in the performance of the electrolysis device.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an electrolysis device capable of suppressing performance degradation. [Means for solving the problem]

[0006] In order to solve the above problems, the electrolysis device according to the present disclosure includes an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber, and an electrolyte solution supply unit having at least one tank for accommodating an electrolyte solution, which circulates a portion of the electrolyte solution between the at least one tank and the anode chamber as a first electrolyte solution and circulates another portion of the electrolyte solution between the at least one tank and the cathode chamber as a second electrolyte solution, and an ion concentration adjustment unit that supplies an adjustment solution for adjusting a hydrogen ion concentration (pH) to the electrolyte solution supply unit. The at least one tank includes a combined tank, the combined tank having a first storage section for storing the first electrolytic solution, a second storage section for storing the second electrolytic solution, and a membrane disposed between the first storage section and the second storage section, through which at least one of ions and water can move between the first storage section and the second storage section. .

[0007] In order to solve the above problems, an electrolysis device according to another aspect of the present disclosure includes an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber, and an electrolyte solution supply unit having a joint tank for accommodating an electrolyte solution, circulating a part of the electrolyte solution between the joint tank and the anode chamber as a first electrolyte solution, and circulating another part of the electrolyte solution between the joint tank and the cathode chamber as a second electrolyte solution, wherein the joint tank has a first container section for accommodating the first electrolyte solution, a second container section for accommodating the second electrolyte solution, and a membrane disposed between the first container section and the second container section, through which at least one of ions and water can move between the first container section and the second container section. The joint tank includes one tank, and the electrolyte supply unit has a partition unit that divides the inside of the tank into the first storage unit that stores the first electrolyte and the second storage unit that stores the second electrolyte, and a first connection unit that is connected to the tank and guides a portion of the first electrolyte stored in the first storage unit to the second storage unit as an adjustment liquid.

[0008] In order to solve the above problems, an electrolysis device according to another aspect of the present disclosure includes an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber, and an electrolyte supply unit having at least one tank for accommodating an electrolyte, and circulating a part of the electrolyte between the at least one tank and the anode chamber as a first electrolyte solution and circulating another part of the electrolyte between the at least one tank and the cathode chamber as a second electrolyte solution, wherein the at least one tank includes a junction tank that accommodates at least a part of the first electrolyte solution and at least a part of the second electrolyte solution by merging them together, and the electrolyte supply unit supplies a part of the electrolyte accommodated in the junction tank to the anode chamber as the first electrolyte solution and supplies the other part of the electrolyte accommodated in the junction tank to the cathode chamber as the second electrolyte solution. The at least one tank includes a joint tank, the joint tank having a first storage section for storing the first electrolytic solution, a second storage section for storing the second electrolytic solution, and a membrane disposed between the first storage section and the second storage section, through which at least one of ions and water can move between the first storage section and the second storage section. do. Effect of the Invention

[0009] According to the electrolysis device of the present disclosure, it is possible to suppress performance degradation. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an electrolysis device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 1 is a cross-sectional view showing an electrolysis cell according to a first embodiment of the present disclosure. [Diagram 3] 2 is a block diagram showing a functional configuration of a control device according to a first embodiment of the present disclosure. FIG. [Figure 4] 4 is a flowchart showing a control flow according to the first embodiment of the present disclosure. [Diagram 5] 6A to 6C are diagrams for explaining an adjustment operation according to the first embodiment of the present disclosure. [Figure 6A] 4 is a table showing a change in hydrogen ion concentration of an electrolytic solution inside a cathode chamber, as an example of an adjustment operation in the first embodiment of the present disclosure. [Figure 6B] 4 is a table showing a change in hydrogen ion concentration of an electrolytic solution inside an anode chamber, as an example of an adjustment operation in the first embodiment of the present disclosure. [Figure 7] 6A to 6C are diagrams for explaining an adjustment operation according to the first embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram showing an electrolysis device according to a first modified example of the first embodiment of the present disclosure. [Figure 9] FIG. 2 is a diagram showing an electrolysis device according to a second embodiment of the present disclosure. [Figure 10] FIG. 13 is a diagram showing an electrolysis device according to a third embodiment of the present disclosure. [Figure 11] FIG. 13 is a diagram showing an electrolysis device according to a fourth embodiment of the present disclosure. [Figure 12] FIG. 11 is a cross-sectional view taken along line F11-F11 of the electrolysis device shown in FIG. [Figure 13] FIG. 12 is a cross-sectional view taken along line F12-F12 of the electrolysis device shown in FIG. [Figure 14] FIG. 11 is a cross-sectional view showing an electrolysis device according to a modified example of the fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an electrolysis device according to an embodiment of the present disclosure will be described with reference to the drawings. In the following description, components having the same or similar functions are denoted by the same reference numerals. Further, duplicated descriptions thereof may be omitted.

[0012] (First embodiment) <1. Configuration of electrolysis device> FIG. 1 is a diagram showing an electrolysis device 1 according to a first embodiment. The electrolysis device 1 is, for example, a device that generates hydrogen by electrolyzing water or an alkaline aqueous solution contained in an electrolytic solution. The electrolysis device 1 is, for example, an anion exchange membrane (AEM) type electrolysis device. However, the electrolysis device 1 is not limited to the above example. The configuration of this embodiment is widely applicable to electrolysis devices in which the hydrogen ion concentration (pH) of the electrolytic solution changes.

[0013] The electrolysis device 1 includes, for example, an electrolytic cell stack 10, a power supply unit 40, an electrolyte supply unit 50, a sensor unit 60, an ion concentration adjustment unit 70, a liquid volume adjustment unit 80, and a control device 90.

[0014] (Electrolysis cell stack) The electrolysis cell stack 10 is an assembly of multiple electrolysis cells 11. For example, the electrolysis cell stack 10 is formed by arranging multiple electrolysis cells 11 in one direction. Each electrolysis cell 11 includes an anode chamber Sa to which an electrolytic solution is supplied and oxygen is produced, and a cathode chamber Sb to which an electrolytic solution is supplied and hydrogen is produced.

[0015] (Power supply part) The power supply unit 40 is a DC power supply device that applies a voltage to each electrolytic cell 11. The power supply unit 40 applies a DC voltage required for electrolysis of the electrolyte between the anode and cathode of each electrolytic cell 11.

[0016] (Electrolyte supply section) The electrolyte supply unit 50 is a supply unit that supplies an electrolyte to each electrolytic cell 11. The electrolyte is, for example, pure water or an alkaline aqueous solution. The electrolyte supply unit 50 has at least one tank that contains an electrolyte, and circulates the electrolyte between the at least one tank and an anode chamber Sa, and circulates the electrolyte between the at least one tank and a cathode chamber Sb.

[0017] (Sensor section) The sensor unit 60 detects a value related to the hydrogen ion concentration (pH) or the amount of the electrolyte. The detection result of the sensor unit 60 is transmitted to the control device 90.

[0018] (Ion concentration adjustment section) The ion concentration adjusting unit 70 is an adjusting device that adjusts the hydrogen ion concentration (pH) of the electrolyte when the hydrogen ion concentration (pH) of the electrolyte satisfies a predetermined condition. For example, when the hydrogen ion concentration (pH) of the electrolyte falls outside the allowable range, the ion concentration adjusting unit 70 supplies an adjusting solution for adjusting the hydrogen ion concentration (pH) to the electrolyte supply unit 50.

[0019] (Liquid volume adjustment section) The liquid volume adjusting unit 80 is an adjusting device that adjusts the volume of the electrolyte (a first electrolyte solution described below) flowing through the anode chamber Sa of the electrolytic cell 11 and / or the volume of the electrolyte (a second electrolyte solution described below) flowing through the cathode chamber Sb of the electrolytic cell 11. For example, the liquid volume adjusting unit 80 adjusts the volume of the first electrolyte solution so that the volume of the first electrolyte solution does not increase beyond an allowable range.

[0020] (Control device) The control device 90 comprehensively controls the entire electrolysis device 1. The control device 90 controls the adjustment operation of the hydrogen ion concentration (pH) by the ion concentration adjustment unit 70 based on, for example, the detection results of the ion concentration sensors 61, 63 and the liquid level sensors 62, 64 described below. The control device 90 also controls the adjustment operation of the liquid volume by the liquid volume adjustment unit 80 based on the detection result of the liquid level sensor 62 described below.

[0021] The electrolysis device 1 having such a configuration will be described in detail below. However, the content described below is merely an example and does not limit the scope of this embodiment.

[0022] <2. Electrolysis cell> First, the electrolytic cell 11 will be described. 2 is a cross-sectional view that diagrammatically illustrates an electrolysis cell 11. The electrolysis cell 11 includes, for example, a first separator 21, a second separator 22, a membrane electrode assembly 23, and a sealing portion 24.

[0023] (First separator) The first separator 21 is a member that defines one side of the internal space S of the electrolysis cell 11. The internal space S is a space that includes an anode chamber Sa and a cathode chamber Sb, which will be described later. The first separator 21 is, for example, in the shape of a rectangular plate, and is made of a metal member. A positive voltage is applied to the first separator 21 from the power supply unit 40, for example, via a current collector (not shown).

[0024] The first separator 21 has a first end 21e1 (e.g., a lower end) and a second end 21e2 (e.g., an upper end) located on the opposite side to the first end 21e1. The first end 21e1 of the first separator 21 is connected to a piping section L1 of the electrolytic solution supply section 50 described later. The second end 21e2 of the first separator 21 is connected to a piping section L2 of the electrolytic solution supply section 50 described later. The first separator 21 has a first inner surface 21a facing the anode chamber Sa described later. The first inner surface 21a is formed with a first flow path FP1 through which the electrolytic solution supplied from the piping section L1 flows. The first flow path FP1 is, for example, a groove provided in the first inner surface 21a. The electrolytic solution that has flowed through the first flow path FP1 is discharged to the outside of the electrolytic cell 11 through the piping section L2. Note that the structures (e.g., flow path structures, etc.) shown in FIG. 2 are merely examples and do not limit the contents of this embodiment. For example, various flow channel structures can be used depending on the size, purpose, and usage environment of the device, and the same applies to the structures shown in the other figures.

[0025] (Second separator) The second separator 22 is disposed with an internal space S between it and at least a part of the first separator 21, and is a member that defines the other side of the internal space S. The second separator 22 is, for example, a rectangular plate and is made of a metal member. A negative voltage is applied to the second separator 22 from the power supply unit 40 via a current collector (not shown).

[0026] The second separator 22 has a first end 22e1 (e.g., a lower end) and a second end 22e2 (e.g., an upper end) located on the opposite side to the first end 22e1. The first end 22e1 of the second separator 22 is connected to a piping section L3 of the electrolytic solution supply section 50 described later. The second end 22e2 of the second separator 22 is connected to a piping section L4 of the electrolytic solution supply section 50 described later. The second separator 22 has a second inner surface 22a facing a cathode chamber Sb described later. The second inner surface 22a is formed with a second flow path FP2 through which the electrolytic solution supplied from the piping section L3 flows. The second flow path FP2 is, for example, a groove provided in the second inner surface 22a. The electrolytic solution that has flowed through the second flow path FP2 is discharged to the outside of the electrolytic cell 11 through the piping section L4.

[0027] For convenience of explanation, the first separator 21 has a groove for a flow path (first flow path FP1), and the second separator 22 has a groove for a flow path (second flow path FP2). However, for example, the first separator 21 of the electrolysis cell 11 included in the electrolysis cell stack 10 (see FIG. 1) may be a bipolar plate having a similar groove for a flow path (first flow path FP1, shown by a two-dot chain line in FIG. 2) on the surface 21b opposite to the first inner surface 21a in addition to the first inner surface 21a. Similarly, the second separator 22 of the electrolysis cell 11 included in the electrolysis cell stack 10 may be a bipolar plate having a similar groove for a flow path (second flow path FP2, shown by a two-dot chain line in FIG. 2) on the surface 22b opposite to the second inner surface 22a in addition to the second inner surface 22a. The grooves for a flow path provided on both sides of the first separator 21 may have different shapes and arrangements. Furthermore, the flow path grooves provided on both sides of the second separator 22 may have different shapes and arrangements.

[0028] (Membrane electrode assembly) The membrane electrode assembly (MEA) 23 is a structure in which an ion exchange membrane, a catalyst, and a power supply are assembled. The membrane electrode assembly 23 is disposed between the first separator 21 and the second separator 22, and is located in the internal space S. The membrane electrode assembly 23 includes, for example, an ion exchange membrane 31, an anode catalyst layer 32, an anode power supply 33, a cathode catalyst layer 34, and a cathode power supply 35.

[0029] (Ion exchange membrane) The ion exchange membrane 31 is a membrane that selectively transmits ions. The ion exchange membrane 31 is, for example, a solid polymer electrolyte membrane. The ion exchange membrane 31 is, for example, an anion exchange membrane (AEM) that is hydroxide ion conductive. However, the ion exchange membrane 31 is not limited to the above example, and may be an ion exchange membrane of a type different from the above example. The ion exchange membrane 31 is, for example, a rectangular sheet. The ion exchange membrane 31 is disposed between the first separator 21 and the second separator 22, and is located in the above-mentioned internal space S. The ion exchange membrane 31 has a first surface 31a that faces the first inner surface 21a of the first separator 21, and a second surface 31b that is located on the opposite side to the first surface 31a and faces the second inner surface 22a of the second separator 22. In the internal space S, an anode chamber Sa is defined between the first surface 31a of the ion exchange membrane 31 and the first inner surface 21a of the first separator 21. In the internal space S, between the second surface 31b of the ion exchange membrane 31 and the second inner surface 22a of the second separator 22, a cathode chamber Sb is defined.

[0030] In the anode chamber Sa, when a voltage is applied to the electrolytic cell 11, the following chemical reaction occurs, producing water and oxygen. In this application, "XX is produced" may also include cases where other substances are produced simultaneously with the production of XX. 2OH - →1 / 2O2+H2O+2e - …(C1)

[0031] In the cathode chamber Sb, when a voltage is applied to the electrolytic cell 11, the following chemical reaction occurs, and water is decomposed to produce hydrogen. The hydroxide ions produced in the cathode chamber Sb pass through the ion exchange membrane 31 and move from the cathode chamber Sb to the anode chamber Sa. 2H2O+2e - →H2+2OH - …(Case 2)

[0032] As a result, the following chemical reactions occur in the electrolytic cell 11 as a whole: H2O→H2+1 / 2O2…(Chem.3)

[0033] Due to the above-mentioned chemical reactions, the electrolyte passing through the anode chamber Sa increases in volume and decreases in hydrogen ion concentration (pH) because water is produced in the anode chamber Sa. On the other hand, the electrolyte passing through the cathode chamber Sb decreases in volume and increases in hydrogen ion concentration (pH) because water is decomposed in the cathode chamber Sb.

[0034] (Anode catalyst layer) The anode catalyst layer 32 is a layer that promotes the chemical reaction in the anode chamber Sa described above. The anode catalyst layer 32 is disposed in the anode chamber Sa, and is adjacent to the ion exchange membrane 31. Note that a portion of the anode catalyst layer 32 may penetrate into the surface portion of the ion exchange membrane 31. A positive voltage is applied to the anode catalyst layer 32 from the power supply unit 40 via the first separator 21 and the anode power supply 33, and the anode catalyst layer 32 functions as a portion of the anode 27 of the battery cell 11.

[0035] (anode current collector) The anode power supply 33 is an electrical connection part that transmits the voltage applied to the first separator 21 to the anode catalyst layer 32. The anode power supply 33 is disposed in the anode chamber Sa. The anode power supply 33 is located between the first inner surface 21a of the first separator 21 and the anode catalyst layer 32, and is in contact with the first inner surface 21a of the first separator 21 and the anode catalyst layer 32, respectively. The anode power supply 33 has a structure that allows the electrolyte and gas to pass through. The anode power supply 33 is formed of, for example, a metal mesh structure, a sintered body, or fibers. In this embodiment, the anode catalyst layer 32 and the anode power supply 33 form the anode 27 of the battery cell 11.

[0036] (Cathode catalyst layer) The cathode catalyst layer 34 is a layer that promotes the chemical reaction in the cathode chamber Sb described above. The cathode catalyst layer 34 is disposed in the cathode chamber Sb and is adjacent to the ion exchange membrane 31. Note that a part of the cathode catalyst layer 34 may penetrate into the surface part of the ion exchange membrane 31. A negative voltage is applied to the cathode catalyst layer 34 from the power supply unit 40 via the second separator 22 and the cathode power supply 35, and the cathode catalyst layer 34 functions as a part of the cathode 28 of the battery cell 11.

[0037] (Cathode feeder) The cathode power supply 35 is an electrical connection part that transmits the voltage applied to the second separator 22 to the cathode catalyst layer 34. The cathode power supply 35 is disposed in the cathode chamber Sb. The cathode power supply 35 is located between the second inner surface 22a of the second separator 22 and the cathode catalyst layer 34, and is in contact with the second inner surface 22a of the second separator 22 and the cathode catalyst layer 34, respectively. The cathode power supply 35 has a structure that allows the electrolyte and gas to pass through. The cathode power supply 35 is formed, for example, of a metal mesh structure, a sintered body, fiber, or carbon paper. In this embodiment, the cathode catalyst layer 34 and the cathode power supply 35 form the cathode 28 of the battery cell 11.

[0038] (Sealing part) The sealing portion 24 is disposed between the first separator 21 and the second separator 22. The sealing portion 24 is located on the outer periphery side of the ion exchange membrane 31, and seals the internal space S of the electrolysis cell 11.

[0039] It should be noted that the electrolysis cell 11 is not limited to the above-mentioned configuration. For example, when a plurality of electrolysis cells 11 are arranged side by side in the electrolysis cell stack 10, two adjacent electrolysis cells 11 among the plurality of electrolysis cells 11 may share the first separator 21 or the second separator 22, which is a bipolar plate.

[0040] <3. Electrolyte supply section> Next, returning to FIG. 1, the electrolyte supply unit 50 will be described. In this disclosure, for convenience of explanation, the electrolyte supplied to the anode chamber Sa of the electrolytic cell 11 may be referred to as the "first electrolyte", and the electrolyte supplied to the cathode chamber Sb of the electrolytic cell 11 may be referred to as the "second electrolyte". However, these names are used only for the purpose of distinction, and the components of the first electrolyte and the second electrolyte may be the same. In this disclosure, the first electrolyte and the second electrolyte may be collectively referred to as the "electrolytic solution".

[0041] As shown in FIG. 1, the electrolyte supply unit 50 has an anode side supply unit 50a that supplies an electrolyte (first electrolyte) to the anode chamber Sa of each electrolytic cell 11, and a cathode side supply unit 50b that supplies an electrolyte (second electrolyte) to the cathode chamber Sb of each electrolytic cell 11.

[0042] (Anode side supply section) The anode side supply unit 50a includes, for example, a first electrolyte tank 51, a first piping unit L1, a second piping unit L2, an oxygen gas-liquid separator 52, an oxygen recovery unit 53, and a first pump .

[0043] (First electrolyte tank) The first electrolyte tank 51 accommodates a first electrolyte. The first electrolyte tank 51 receives the first electrolyte containing oxygen generated in the anode chamber Sa of the electrolytic cell 11 from the electrolytic cell 11. The first electrolyte tank 51 is an example of a "first tank."

[0044] (First piping section) The first piping section L1 is a flow path section that guides the first electrolytic solution contained in the first electrolytic solution tank 51 to the anode chamber Sa of the electrolytic cell 11. The first piping section L1 extends between a supply port of the first electrolytic solution tank 51 and an inlet of the first flow path FP1 of the electrolytic cell 11.

[0045] (Second piping section) The second piping section L2 is a flow path section that guides the first electrolytic solution that has passed through the anode chamber Sa of the electrolytic cell 11 to the first electrolytic solution tank 51. The second piping section L2 extends between the outlet of the first flow path FP1 of the electrolytic cell 11 and the return port of the first electrolytic solution tank 51. The second piping section L2 is an example of a "first flow path section."

[0046] (Oxygen gas-liquid separator) The oxygen gas-liquid separator 52 is a gas-liquid separator that separates oxygen contained in the first electrolytic solution. The oxygen gas-liquid separator 52 is provided in the first electrolytic solution tank 51. For example, the oxygen gas-liquid separator 52 is provided between the return port of the first electrolytic solution tank 51 and the second piping section L2. The first electrolytic solution flowing from the second piping section L2 toward the first electrolytic solution tank 51 flows into the oxygen gas-liquid separator 52, and the oxygen contained in the first electrolytic solution is separated. The oxygen separated from the first electrolytic solution by the oxygen gas-liquid separator 52 is collected by the oxygen collection section 53.

[0047] (First pump) The first pump 54 is a pump for supplying the first electrolyte contained in the first electrolyte tank 51 to the anode chamber Sa of the battery cell 11. The first pump 54 is provided, for example, midway along the first piping section L1.

[0048] (Cathode side supply section) The cathode side supply unit 50b includes, for example, a second electrolyte tank 56, a third piping section L3, a fourth piping section L4, a hydrogen gas-liquid separator 57, a hydrogen recovery section 58, and a second pump 59.

[0049] (Second electrolyte tank) The second electrolyte tank 56 contains a second electrolyte. The second electrolyte tank 56 receives the second electrolyte containing hydrogen generated in the cathode chamber Sb of the electrolytic cell 11 from the electrolytic cell 11. The second electrolyte tank 56 is an example of a "second tank."

[0050] (Third piping section) The third piping section L3 is a flow path section that guides the second electrolytic solution contained in the second electrolytic solution tank 56 to the cathode chamber Sb of the electrolytic cell 11. The third piping section L3 extends between the supply port of the second electrolytic solution tank 56 and the inlet of the second flow path FP2 of the electrolytic cell 11.

[0051] (4th piping section) The fourth piping section L4 is a flow path section that guides the second electrolytic solution that has passed through the cathode chamber Sb of the electrolytic cell 11 to the second electrolytic solution tank 56. The fourth piping section L4 extends between the outlet of the second flow path FP2 of the electrolytic cell 11 and the return port of the second electrolytic solution tank 56. The fourth piping section L4 is an example of a "second flow path section."

[0052] (Hydrogen gas-liquid separator) The hydrogen gas-liquid separator 57 is a gas-liquid separator that separates hydrogen contained in the second electrolytic solution. The hydrogen gas-liquid separator 57 is provided in the second electrolytic solution tank 56. For example, the hydrogen gas-liquid separator 57 is provided between the return port of the second electrolytic solution tank 56 and the fourth piping section L4. The second electrolytic solution flowing from the fourth piping section L4 toward the second electrolytic solution tank 56 flows into the hydrogen gas-liquid separator 57, and hydrogen contained in the second electrolytic solution is separated. The hydrogen separated from the second electrolytic solution by the hydrogen gas-liquid separator 57 is collected by the hydrogen recovery section 58.

[0053] (Second pump) The second pump 59 is a pump for supplying the second electrolyte contained in the second electrolyte tank 56 to the cathode chamber Sb of the battery cell 11. The second pump 59 is provided, for example, midway through the third piping section L3.

[0054] <4. Sensor section> Next, the sensor unit 60 will be described. In this embodiment, the sensor unit 60 includes a first ion concentration sensor 61, a first liquid level sensor 62, a second ion concentration sensor 63, and a second liquid level sensor 64. One or more of these sensors may be omitted. For example, one of the first ion concentration sensor 61 and the first liquid level sensor 62 may be omitted. One of the second ion concentration sensor 63 and the second liquid level sensor 64 may be omitted. Each of the first ion concentration sensor 61 and the first liquid level sensor 62 is an example of a "first sensor." Each of the second ion concentration sensor 63 and the second liquid level sensor 64 is an example of a "second sensor."

[0055] (First ion concentration sensor) The first ion concentration sensor 61 is provided in the first electrolyte tank 51 and detects the hydrogen ion concentration (pH) of the first electrolyte contained in the first electrolyte tank 51. The detected value of the hydrogen ion concentration (pH) of the first electrolyte is an example of a "value related to the hydrogen ion concentration (pH) of the electrolyte." In the present disclosure, the "value related to the hydrogen ion concentration (pH) of the electrolyte" detected by the sensor is not limited to the hydrogen ion concentration (pH) itself, and may be another physical quantity having a specific relationship with the hydrogen ion concentration (pH) (for example, electrical conductivity or a solute concentration of the electrolyte (for example, the concentration of KOH)). For example, the sensor included in the sensor unit 60 is not limited to an ion concentration sensor, and may be a KOH concentration meter sensor or the like. The same applies to the second ion concentration sensor 63.

[0056] (First liquid level sensor) The first liquid level sensor 62 is provided in the first electrolyte tank 51 and detects the liquid level of the first electrolyte contained in the first electrolyte tank 51. The first liquid level sensor 62 is a sensor that detects the position of the liquid surface based on the position of a float or ultrasonic waves, but is not limited thereto. The detected value of the liquid level of the first electrolyte is an example of a "value related to the liquid volume of the electrolyte." In the present disclosure, the "value related to the liquid volume of the electrolyte" detected by the sensor is not limited to the liquid level of the electrolyte, and may be another physical quantity having a specific relationship with the liquid volume of the electrolyte (for example, the pressure in a container containing the electrolyte). For example, the sensor included in the sensor unit 60 is not limited to a liquid level sensor, and may be a pressure sensor, etc. The same applies to the second liquid level sensor 64.

[0057] (Second ion concentration sensor) The second ion concentration sensor 63 is provided in the second electrolyte tank 56, and detects the hydrogen ion concentration (pH) of the second electrolyte contained in the second electrolyte tank 56. The detected value of the hydrogen ion concentration (pH) of the second electrolyte is an example of a "value related to the hydrogen ion concentration (pH) of the electrolyte."

[0058] (Second liquid level sensor) The second liquid level sensor 64 is provided in the second electrolyte tank 56 and detects the liquid level of the second electrolyte contained in the second electrolyte tank 56. The second liquid level sensor 64 is a sensor that detects the position of the liquid surface based on the position of a float or ultrasonic waves, but is not limited to these. The detected value of the liquid level of the second electrolyte is an example of a "value related to the liquid volume of the electrolyte".

[0059] <5. Ion concentration adjustment section> Next, the ion concentration adjustment unit 70 will be described. The ion concentration adjustment unit 70 is a device that supplies an adjustment liquid for adjusting the hydrogen ion concentration (pH) to the electrolyte supply unit 50. In this embodiment, the ion concentration adjustment unit 70 supplies the adjustment liquid to the electrolyte supply unit 50 when the detection result of the sensor included in the sensor unit 60 satisfies a predetermined condition.

[0060] In this embodiment, the adjusting liquid supplied by the ion concentration adjusting unit 70 includes a first adjusting liquid for increasing the hydrogen ion concentration (pH) and a second adjusting liquid for decreasing the hydrogen ion concentration (pH). The first adjusting liquid is, for example, an alkaline aqueous solution such as a potassium hydroxide aqueous solution (KOH) having a predetermined concentration or higher (for example, 1 mol / L or higher). The second adjusting liquid is, for example, water (H2O). The ion concentration adjusting unit 70 has a first adjusting unit 70A that supplies the first adjusting liquid to the electrolyte supplying unit 50, and a second adjusting unit 70B that supplies the second adjusting liquid to the electrolyte supplying unit 50.

[0061] (1st adjustment section) The first adjustment unit 70A is a device that supplies a first adjusting solution to a first portion (for example, any one of the first electrolyte tank 51, the first piping section L1, or the second piping section L2) in which the first electrolyte solution is stored or through which the first electrolyte solution flows in the electrolyte solution supply unit 50. In this embodiment, the first adjustment unit 70A is disposed upstream of the first electrolyte solution tank 51 in the flow direction of the electrolyte solution, and is connected to the second piping section L2. The first adjustment unit 70A increases the hydrogen ion concentration (pH) of the first electrolyte solution by supplying the first adjusting solution to the inside of the second piping section L2.

[0062] In this embodiment, the first adjustment unit 70A has a tank 71 and a valve 72. The tank 71 contains the first adjusting liquid. The valve 72 is provided between the tank 71 and the second piping section L2. The valve 72 is switchable between an open state in which the first adjusting liquid contained in the tank 71 passes toward the second piping section L2 and a closed state in which the first adjusting liquid contained in the tank 71 is prevented from passing toward the second piping section L2. The valve 72 is switched between an open state and a closed state based on a control signal from a control device 90, which will be described later. The first adjustment unit 70A supplies the first adjusting liquid to the inside of the second piping section L2 by switching the valve 72 from a closed state to an open state based on a control signal from the control device 90.

[0063] In this embodiment, the first adjustment unit 70A supplies the first adjustment liquid to the inside of the second piping unit L2 when the detection result of the first ion concentration sensor 61 is less than a predetermined threshold value Th11 (see FIG. 5). The threshold value Th11 is a threshold value that corresponds to the lower limit of the allowable range of the hydrogen ion concentration (pH) of the electrolyte. The detection result of the first ion concentration sensor 61 being less than the threshold value Th11 is an example of "the detection result of the sensor satisfying the first predetermined condition."

[0064] Alternatively / in addition to the above, the first adjustment unit 70A may supply the first adjustment liquid into the second piping unit L2 when the detection result of the first liquid level sensor 62 is equal to or greater than a predetermined threshold value Th21 (see FIG. 7). The threshold value Th21 is a threshold value that corresponds to the upper limit of the allowable range of the increase in the first electrolyte (i.e., the dilution amount of the electrolyte). In other words, the threshold value Th21 is a threshold value that corresponds to the lower limit of the allowable range of the hydrogen ion concentration (pH) of the electrolyte. The detection result of the first liquid level sensor 62 being equal to or greater than the threshold value Th21 is another example of "the detection result of the sensor satisfying a first predetermined condition."

[0065] (2nd adjustment section) The second adjustment unit 70B is a device that supplies the second adjustment liquid to a second portion (for example, the second electrolyte tank 56, the third piping section L3, or the fourth piping section L4) in which the second electrolyte is stored or through which the second electrolyte flows in the electrolyte supply unit 50. In this embodiment, the second adjustment unit 70B is disposed upstream of the second electrolyte tank 56 in the electrolyte flow direction and is connected to the fourth piping section L4. The second adjustment unit 70B lowers the hydrogen ion concentration (pH) of the second electrolyte by supplying the second adjustment liquid to the inside of the fourth piping section L4.

[0066] In this embodiment, the second adjustment unit 70B has a tank 73 and a valve 74. The tank 73 contains the second adjusting liquid. The valve 74 is provided between the tank 73 and the fourth piping section L4. The valve 74 is switchable between an open state in which the second adjusting liquid contained in the tank 73 passes toward the fourth piping section L4 and a closed state in which the second adjusting liquid contained in the tank 73 is prevented from passing toward the second piping section L2. The valve 74 is switched between an open state and a closed state based on a control signal from a control device 90, which will be described later. The second adjustment unit 70B supplies the second adjusting liquid to the inside of the fourth piping section L4 by switching the valve 74 from a closed state to an open state based on a control signal from the control device 90.

[0067] In this embodiment, the second adjustment unit 70B supplies the second adjustment liquid to the inside of the fourth piping unit L4 when the detection result of the second ion concentration sensor 63 is equal to or greater than a predetermined threshold value Th12 (see FIG. 5). The threshold value Th12 is a threshold value that corresponds to the upper limit of the allowable range of the hydrogen ion concentration (pH) of the electrolyte. The detection result of the second ion concentration sensor 63 being equal to or greater than the threshold value Th12 is an example of "the detection result of the sensor satisfying the second predetermined condition."

[0068] Alternatively / in addition to the above, the second adjustment unit 70B may supply the second adjustment liquid to the inside of the fourth piping unit L4 when the detection result of the second liquid level sensor 64 is less than a predetermined threshold value Th22 (see FIG. 7). The threshold value Th22 is a threshold value corresponding to the upper limit of the allowable range of the decrease in the amount of the second electrolytic solution (i.e., the concentration of the electrolytic solution). In other words, the threshold value Th22 is a threshold value corresponding to the upper limit of the allowable range of the hydrogen ion concentration (pH) of the electrolytic solution. The detection result of the second liquid level sensor 64 being less than the threshold value Th22 is another example of "the detection result of the sensor satisfying the second predetermined condition."

[0069] <6. Liquid volume adjustment section> Next, the liquid amount adjusting unit 80 will be described. The liquid amount adjusting unit 80 is an adjusting unit for reducing the amount of the first electrolytic solution that increases as electrolysis progresses. In this embodiment, the liquid amount adjusting unit 80 has, for example, a connection pipe 81 and a discharge pipe 85. At least one of the connection pipe 81 and the discharge pipe 85 may be omitted.

[0070] (Connection piping) The connection pipe 81 is a bypass pipe for moving a portion of the first electrolytic solution contained in the first electrolytic solution tank 51 to the second electrolytic solution tank 56. The connection pipe 81 connects, for example, the bottom of the first electrolytic solution tank 51 and the bottom of the second electrolytic solution tank 56. The connection pipe 81 is an example of a "connection part".

[0071] For example, when the first electrolyte tank 51 and the second electrolyte tank 56 are installed at the same height, a part of the first electrolyte moves from the first electrolyte tank 51 to the second electrolyte tank 56 through the connecting pipe 81 due to a head pressure based on the difference between the liquid level of the first electrolyte that increases due to electrolysis and the liquid level of the second electrolyte that decreases due to electrolysis. In this case, the water pump 83 described later and the like may be omitted.

[0072] The connection pipe 81 may be provided with a water supply valve 82 and / or a water supply pump 83 for adjusting the amount of movement of the first electrolytic solution flowing from the first electrolytic solution tank 51 toward the second electrolytic solution tank 56. The connection pipe 81 may also be provided with a gas-liquid separator 84 for separating air remaining in the first electrolytic solution flowing from the first electrolytic solution tank 51 toward the second electrolytic solution tank 56. By providing the gas-liquid separator 84, it is possible to more reliably prevent oxygen and hydrogen from being mixed together.

[0073] (Discharge piping) The discharge pipe 85 is a pipe for discharging a part of the first electrolytic solution contained in the first electrolytic solution tank 51 to the outside. The discharge pipe 85 connects, for example, the bottom of the first electrolytic solution tank 51 to an external electrolytic solution recovery unit 86. The discharge pipe 85 is an example of a "discharge unit". Note that the discharge pipe 85 may be provided with a discharge valve 87 for adjusting the discharge amount of the first electrolytic solution flowing from the first electrolytic solution tank 51 toward the electrolytic solution recovery unit 86.

[0074] <7. Control device> Next, the control device 90 will be described. 3 is a block diagram showing a functional configuration of the control device 90. Detection results of the sensors 61, 62, 63, and 64 included in the sensor unit 60 are transmitted to the control device 90. The control device 90 controls the ion concentration adjustment unit 70 based on the detection results of the sensor unit 60 (e.g., the detection results of one or more of the sensors 61, 62, 63, and 64), thereby controlling the operation of supplying an adjustment solution to the electrolyte solution supply unit 50.

[0075] In this embodiment, when the detection result of the first ion concentration sensor 61 is less than the threshold value Th11, the control device 90 transmits a control signal to the valve 72 of the first adjustment unit 70A to switch the valve 72 from a closed state to an open state. This causes the first adjustment liquid to be supplied to the inside of the second piping section L2 by the first adjustment unit 70A. Note that instead of / in addition to the above, when the detection result of the first liquid level sensor 62 is equal to or greater than the threshold value Th21, the control device 90 may transmit a control signal to the valve 72 of the first adjustment unit 70A to switch the valve 72 from a closed state to an open state.

[0076] In this embodiment, when the detection result of the second ion concentration sensor 63 is equal to or greater than the threshold value Th12, the control device 90 transmits a control signal to the valve 74 of the second adjustment unit 70B to switch the valve 74 from a closed state to an open state. This causes the second adjustment liquid to be supplied to the inside of the fourth piping section L4 by the second adjustment unit 70B. Note that instead of / in addition to the above, when the detection result of the second liquid level sensor 64 is less than the threshold value Th22, the control device 90 may transmit a control signal to the valve 74 of the second adjustment unit 70B to switch the valve 74 from a closed state to an open state.

[0077] In this embodiment, when the detection result of the first liquid level sensor 62 is equal to or greater than the threshold value Th21 (or another threshold value), the control device 90 may send a control signal to one or more of the water supply valve 82 of the liquid volume adjustment unit 80, the water supply pump 83 of the liquid volume adjustment unit 80, and the drain valve 87 of the liquid volume adjustment unit 80, to adjust the volume of the first electrolyte contained in the first electrolyte tank 51.

[0078] In this embodiment, when the detection result of the sensor unit 60 satisfies a predetermined condition during operation of the electrolysis device 1 (during water electrolysis), the control device 90 controls the ion concentration adjustment unit 70 to adjust the hydrogen ion concentration (pH) of the electrolyte while continuing operation of the electrolysis device 1. Furthermore, when the detection result of the sensor unit 60 satisfies a predetermined condition during operation of the electrolysis device 1, the control device 90 controls the liquid volume adjustment unit 80 to adjust the volume of the electrolyte while continuing operation of the electrolysis device 1.

[0079] <8. Control Flow> Next, the flow of control regarding the electrolysis device 1 will be described. 4 is a flowchart showing a control flow for adjusting the hydrogen ion concentration (pH) of the electrolyte. Note that, here, an example will be described in which the hydrogen ion concentration (pH) of the electrolyte is adjusted based on the detection results of the first ion concentration sensor 61 and the second ion concentration sensor 63.

[0080] First, the control device 90 acquires the hydrogen ion concentrations (pH) of the first electrolytic solution and the second electrolytic solution based on the detection results of the first ion concentration sensor 61 and the second ion concentration sensor 63 at a predetermined period during operation of the electrolytic device 1 (during water electrolysis) (S101).

[0081] Next, the control device 90 determines whether the hydrogen ion concentration (pH) of the second electrolytic solution is equal to or greater than the upper limit of the allowable range (second threshold value Th12) (S102). If the hydrogen ion concentration (pH) of the second electrolytic solution is less than the upper limit of the allowable range (S102: NO), the control device 90 skips the process of S103. On the other hand, if the hydrogen ion concentration (pH) of the second electrolytic solution is equal to or greater than the upper limit of the allowable range (S102: YES), the control device 90 sends a control signal to the second adjustment unit 70B to cause the second adjustment unit 70B to supply the second adjustment solution (S103).

[0082] Next, the control device 90 determines whether the hydrogen ion concentration (pH) of the first electrolytic solution is less than the lower limit of the allowable range (first threshold value Th11) (S104). If the hydrogen ion concentration (pH) of the first electrolytic solution is equal to or greater than the lower limit of the allowable range (S104: NO), the control device 90 skips the process of S105. On the other hand, if the hydrogen ion concentration (pH) of the first electrolytic solution is less than the lower limit of the allowable range (S104: YES), the control device 90 sends a control signal to the first adjustment unit 70A to cause the first adjustment unit 70A to supply the first adjustment solution (S105).

[0083] The process for the second electrolytic solution (the processes in S102 and S103) and the process for the first electrolytic solution (the processes in S104 and S105) may be performed either first or simultaneously.

[0084] FIG. 5 is a diagram for explaining the operation of adjusting the hydrogen ion concentration (pH). In this embodiment, the control device 90 monitors the hydrogen ion concentration (pH) of the second electrolytic solution during operation of the electrolytic device 1, and supplies the second adjusting solution to the cathode chamber Sb by the second adjusting unit 70B every time the hydrogen ion concentration (pH) of the second electrolytic solution exceeds the upper limit value (threshold value TH12) of the allowable range. This keeps the hydrogen ion concentration (pH) of the second electrolytic solution in the cathode chamber Sb within the allowable range. Similarly, the control device 90 monitors the hydrogen ion concentration (pH) of the first electrolytic solution during operation of the electrolytic device 1, and supplies the first adjusting solution to the anode chamber Sa by the first adjusting unit 70A every time the hydrogen ion concentration (pH) of the first electrolytic solution falls below the lower limit value (threshold value Th11) of the allowable range. This keeps the hydrogen ion concentration (pH) of the first electrolytic solution in the anode chamber Sa within the allowable range.

[0085] A specific example of the operation will be described with reference to Fig. 6A and Fig. 6B. The power supply unit 40 started applying a voltage to the electrolytic cell 11, and the hydrogen ion concentration (pH) of the second electrolytic solution in the cathode chamber Sb gradually increased over time. Then, the hydrogen ion concentration (pH) of the second electrolytic solution exceeded the threshold value Th12, and the second adjustment solution was supplied to the cathode chamber Sb by the second adjustment unit 70B, and the hydrogen ion concentration (pH) of the second electrolytic solution decreased (A in Fig. 5). After that, as time passed, the hydrogen ion concentration (pH) of the second electrolytic solution in the cathode chamber Sb again exceeded the threshold value Th12 (B in Fig. 5), and the second adjustment solution was supplied to the cathode chamber Sb by the second adjustment unit 70B, and the hydrogen ion concentration (pH) of the second electrolytic solution decreased again (C in Fig. 5). The above operation was repeated thereafter. As shown in Fig. 6A, if the hydrogen ion concentration (pH) of the second electrolyte solution after the nth supply of the second adjustment solution is taken as a reference value (Rf), when the hydrogen ion concentration (pH) of the second electrolyte solution exceeded the threshold value Th12 the n+1th time (before the second adjustment solution was supplied, B in Fig. 5), it was 0.14 above the reference value. The hydrogen ion concentration (pH) of the second electrolyte solution after the n+1th supply of the second adjustment solution (C in Fig. 5) was 0.02 above the reference value.

[0086] Similarly, the power supply unit 40 started applying a voltage to the electrolytic cell 11, and the hydrogen ion concentration (pH) of the first electrolytic solution in the anode chamber Sa gradually decreased over time. Then, the hydrogen ion concentration (pH) of the first electrolytic solution fell below the threshold value Th11, so the first adjustment unit 70A supplied the first adjustment solution to the anode chamber Sa, and the hydrogen ion concentration (pH) of the first electrolytic solution increased (D in FIG. 5). After that, as more time passed, the hydrogen ion concentration (pH) of the first electrolytic solution in the anode chamber Sa fell below the threshold value Th11 again (E in FIG. 5), so the first adjustment unit 70A supplied the first adjustment solution to the anode chamber Sa, and the hydrogen ion concentration (pH) of the second electrolytic solution increased again (F in FIG. 5). The above operations were then repeated. As shown in Fig. 6B, if the hydrogen ion concentration (pH) of the first electrolyte solution after the nth supply of the first adjustment solution is taken as a reference value (Rf), when the hydrogen ion concentration (pH) of the first electrolyte solution fell below the threshold value Th11 the (n+1)th time (before the supply of the first adjustment solution, E in Fig. 5) was minus 0.14 compared to the reference value. The hydrogen ion concentration (pH) of the first electrolyte solution after the n+1th supply of the first adjustment solution (F in Fig. 5) was minus 0.03 compared to the reference value.

[0087] FIG. 7 is a diagram for explaining the operation in the case where the hydrogen ion concentration (pH) is adjusted based on the liquid level of the electrolytic solution. In the example shown in FIG. 7, the control device 90 monitors the liquid level of the second electrolytic solution in the cathode chamber Sb during operation of the electrolytic device 1, and supplies the second adjusting solution to the cathode chamber Sb by the second adjusting unit 70B every time the liquid level of the second electrolytic solution falls below the lower limit (threshold Th22) of the allowable range. This keeps the hydrogen ion concentration (pH) and liquid level of the second electrolytic solution in the cathode chamber Sb within the allowable range. In addition, the control device 90 monitors the liquid level of the first electrolytic solution in the anode chamber Sa during operation of the electrolytic device 1, and supplies the first adjusting solution to the anode chamber Sa by the first adjusting unit 70A and reduces the liquid amount of the first electrolytic solution by the liquid amount adjusting unit 80 every time the liquid level of the first electrolytic solution exceeds the upper limit (threshold Th21) of the allowable range. This keeps the hydrogen ion concentration (pH) and liquid level of the first electrolytic solution in the anode chamber Sa within the allowable range.

[0088] <9. Advantages> For example, in electrolysis devices such as AEM type, as electrolysis progresses, the hydrogen ion concentration (pH) of the electrolyte changes due to the concentration or dilution of the electrolyte. When the hydrogen ion concentration (pH) of the electrolyte changes, the electrical conductivity of the electrolyte changes, which may lead to a decrease in the performance of the electrolysis device.

[0089] Therefore, in this embodiment, the electrolysis device 1 has an ion concentration adjustment unit 70 that supplies an adjustment liquid for adjusting the hydrogen ion concentration (pH) to the electrolyte solution supply unit 50. With this configuration, when the hydrogen ion concentration (pH) of the electrolyte solution changes, the ion concentration of the electrolyte solution can be maintained within a certain range by adding the adjustment liquid to the electrolyte solution. This makes it possible to suppress changes in the electrical conductivity of the electrolyte solution and suppress deterioration in the performance of the electrolysis device.

[0090] (Modification) Next, a description will be given of a modified example of the first embodiment. This modified example may be realized in appropriate combination with the second and third embodiments described later.

[0091] 8 is a diagram showing an electrolysis device 1A according to a first modified example of the first embodiment. In this modified example, the electrolyte supply unit 50 has a first stirrer 101, a second stirrer 102, a first mixer 103, and a second mixer 104. Note that one or more of the first stirrer 101, the second stirrer 102, the first mixer 103, and the second mixer 104 may be omitted.

[0092] The first stirrer 101 is a device that stirs the first electrolytic solution inside the first electrolytic solution tank 51. The first stirrer 101 includes a rotating member 101a that is rotatable inside the first electrolytic solution tank 51. The rotation of the rotating member 101a inside the first electrolytic solution tank 51 promotes mixing of the first electrolytic solution contained in the first electrolytic solution tank 51 and the first adjustment solution supplied by the first adjustment unit 70A.

[0093] The second stirrer 102 is a device that stirs the second electrolytic solution inside the second electrolytic solution tank 56. The second stirrer 102 includes a rotating member 102a that is rotatable inside the second electrolytic solution tank 56. By rotating the rotating member 102a inside the second electrolytic solution tank 56, mixing of the second electrolytic solution contained in the second electrolytic solution tank 56 and the second adjustment solution supplied by the second adjustment unit 70B is promoted.

[0094] The first mixer 103 is provided downstream of the first adjustment unit 70A in the second piping section L2, and is a device that promotes mixing of the first electrolytic solution flowing through the second piping section L2 and the first adjusting solution supplied by the first adjustment unit 70A. For example, the first mixer 103 includes a spiral section 103a provided in the second piping section L2. The spiral section 103a has a spiral groove or protrusion, and promotes mixing of the first electrolytic solution and the first adjusting solution by rotating the flow of the first electrolytic solution.

[0095] The second mixer 104 is provided downstream of the second adjustment unit 70B in the fourth piping section L4, and is a device that promotes mixing of the second electrolytic solution flowing through the fourth piping section L4 and the second adjusting solution supplied by the second adjustment unit 70B. For example, the second mixer 104 includes a spiral section 104a provided in the fourth piping section L4. The spiral section 104a has a spiral groove or protrusion, and promotes mixing of the second electrolytic solution and the second adjusting solution by rotating the flow of the second electrolytic solution.

[0096] Such a configuration promotes mixing of the electrolytic solution and the adjusting solution, which makes it easier for the hydrogen ion concentration (pH) of the electrolytic solution to become uniform. If the hydrogen ion concentration (pH) of the electrolytic solution can be easily made uniform, the performance of the electrolysis device 1 can be further improved.

[0097] Second embodiment Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that a common tank 110 is provided. Note that the configuration other than that described below is the same as that of the first embodiment.

[0098] 9 is a diagram showing an electrolysis device 1B of a second embodiment. In this embodiment, the electrolysis device 1B has a combined tank 110 instead of the first electrolytic solution tank 51 and the second electrolytic solution tank 56. The combined tank 110 is a single tank into which both the first electrolytic solution and the second electrolytic solution flow.

[0099] The joint tank 110 has, for example, a first container 111, a second container 112, and a diaphragm 113.

[0100] The first storage unit 111 is a region (space) that stores the first electrolytic solution inside the joint tank 110. The first storage unit 111 is connected to the second piping unit L2 via the first gas-liquid separator 52. The first electrolytic solution flowing through the second piping unit L2 passes through the first gas-liquid separator 52 to separate oxygen, and is then stored in the first storage unit 111. The first storage unit 111 is also connected to the first piping unit L1. The first electrolytic solution stored in the first storage unit 111 is supplied to the anode chamber Sa of the electrolytic cell 11 via the first piping unit L1.

[0101] The second storage section 112 is a region (space) that stores the second electrolytic solution inside the joint tank 110. The second storage section 112 is connected to the fourth piping section L4 via the second gas-liquid separator 57. The second electrolytic solution flowing through the fourth piping section L4 passes through the second gas-liquid separator 57, whereby hydrogen is separated from the second electrolytic solution, and the second electrolytic solution is then stored in the second storage section 112. The second storage section 112 is also connected to the third piping section L3. The second electrolytic solution stored in the second storage section 112 is supplied to the cathode chamber Sb of the electrolytic cell 11 via the third piping section L3.

[0102] The diaphragm 113 is disposed between the first container 111 and the second container 112 and allows at least one of ions and water (e.g., both) to move between the first container 111 and the second container 112. The material of the diaphragm 113 is not particularly limited as long as it allows at least one of ions and water (e.g., both) to move while preventing mixing of oxygen contained in the first electrolytic solution and hydrogen contained in the second electrolytic solution. The diaphragm 113 is, for example, a porous membrane that is liquid permeable, ion permeable, alkali resistant, and gas impermeable. The diaphragm 113 is, for example, a diaphragm for alkaline water electrolysis. Examples of the material of the diaphragm 113 include fluororesin impregnated with potassium titanate, polyantimonic acid, polysulfone, hydrophilized polyphenylene sulfide, polyvinylidene fluoride, and polytetrafluoroethylene.

[0103] When the diaphragm 113 has ion permeability, ions move between the first and second electrolytic solutions, and the difference in hydrogen ion concentration (pH) between the first and second electrolytic solutions becomes smaller (e.g., becomes homogenized). That is, the hydrogen ion concentration (pH) of the second electrolytic solution decreases, while the hydrogen ion concentration (pH) of the first electrolytic solution increases.

[0104] When membrane 113 is liquid permeable, water moves between the first and second electrolytic solutions, and the difference in the liquid volume between the first and second electrolytic solutions becomes smaller (e.g., becomes homogenized). That is, the liquid volume of the first electrolytic solution decreases, while the liquid volume of the second electrolytic solution increases.

[0105] According to this configuration, in addition to the effects of the first embodiment, the following effects are obtained. That is, at least one of ions and water moves between the first electrolytic solution and the second electrolytic solution in one joint tank 110, so that the difference in at least one of the hydrogen ion concentration (pH) and the liquid volume between the first electrolytic solution and the second electrolytic solution is reduced. This makes it possible to reduce the amount of adjustment operations by the ion concentration adjustment unit 70. Note that, when the hydrogen ion concentrations (pH) of the first electrolytic solution and the second electrolytic solution are homogenized by providing the joint tank 110, the ion concentration adjustment unit 70 may be omitted.

[0106] Third embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment in that a junction tank 121 is provided. Note that the configuration other than that described below is the same as that of the first embodiment.

[0107] 10 is a diagram showing an electrolysis apparatus 1C according to a third embodiment. In this embodiment, the electrolytic solution supply unit 50 has a junction tank 121, an oxygen gas-liquid separator 122, and a hydrogen gas-liquid separator 123.

[0108] (Confluence tank) The junction tank 121 is a tank that contains at least a part of the first electrolytic solution and at least a part of the second electrolytic solution in a junction state. In this embodiment, the junction tank 121 is disposed downstream of the first electrolytic solution tank 51 and the second electrolytic solution tank 56 in the flow direction of the electrolytic solution. The first electrolytic solution from which a large amount of oxygen has been separated by the oxygen gas-liquid separator 52 and contained in the first electrolytic solution tank 51, and the second electrolytic solution from which a large amount of hydrogen has been separated by the hydrogen gas-liquid separator 57 and contained in the second electrolytic solution tank 56 flow into the junction tank 121. The junction tank 121 does not have a membrane or the like, and the first electrolytic solution and the second electrolytic solution are freely mixed together. This adjusts the hydrogen ion concentration (pH) of the first electrolytic solution and the second electrolytic solution. In addition, the liquid amounts of the first electrolytic solution and the second electrolytic solution are adjusted.

[0109] In this embodiment, the entire first electrolytic solution contained in the first electrolytic solution tank 51 and the entire second electrolytic solution contained in the second electrolytic solution tank 56 flow into the junction tank 121. Alternatively, only a part of the first electrolytic solution contained in the first electrolytic solution tank 51 and only a part of the second electrolytic solution contained in the second electrolytic solution tank 56 may flow into the junction tank 121. That is, the electrolytic solution supply unit 50 may have a piping section that supplies a part of the first electrolytic solution contained in the first electrolytic solution tank 51 to the anode chamber Sa of the electrolytic cell 11 without passing through the junction tank 121. Similarly, the electrolytic solution supply unit 50 may have a piping section that supplies a part of the second electrolytic solution contained in the second electrolytic solution tank 56 to the cathode chamber Sb of the electrolytic cell 11 without passing through the junction tank 121.

[0110] A fifth piping section L5 is connected to the bottom of the junction tank 121. The fifth piping section L5 branches midway and is connected to the first piping section L1 and the third piping section L3. The electrolytic solution contained in the junction tank 121 is supplied to the electrolytic cell 11 through the fifth piping section L5, the first piping section L1, and the third piping section L3.

[0111] (Oxygen gas-liquid separator) The oxygen gas-liquid separator 122 is a gas-liquid separation section provided between the first electrolytic solution tank 51 and the junction tank 121. The oxygen gas-liquid separator 122 separates the oxygen remaining in the first electrolytic solution. The separated oxygen is sent to the oxygen recovery section 53. The oxygen gas-liquid separator 122 is an example of a "first gas-liquid separation section."

[0112] (Hydrogen gas-liquid separator) The hydrogen gas-liquid separator 123 is a gas-liquid separation unit provided between the second electrolytic solution tank 56 and the junction tank 121. The hydrogen gas-liquid separator 123 separates hydrogen remaining in the second electrolytic solution. The separated hydrogen is sent to the hydrogen recovery unit 58. The hydrogen gas-liquid separator 123 is an example of a "second gas-liquid separation unit."

[0113] (Ion concentration sensor) The ion concentration sensor 61 is provided in the junction tank 121. The ion concentration sensor 61 detects the ion concentration of the electrolytic solution after the first electrolytic solution and the second electrolytic solution are joined in the junction tank 121.

[0114] (Ion concentration adjustment section) The ion concentration adjuster 70 is provided in the junction tank 121. The ion concentration adjuster 70 supplies an adjustment liquid to the junction tank 121. For example, the ion concentration adjuster 70 has a first adjuster 70A and a second adjuster 70B, similar to the first embodiment. In this embodiment, when the detection result of the ion concentration sensor 61 is less than the threshold value Th11 (a threshold value corresponding to the lower limit value of the allowable range of the hydrogen ion concentration (pH)), the first adjuster 70A supplies the first adjustment liquid to the inside of the junction tank 121. On the other hand, when the detection result of the ion concentration sensor 61 is equal to or greater than the threshold value Th12 (the upper limit value of the allowable range of the hydrogen ion concentration (pH)), the second adjuster 70B supplies the second adjustment liquid to the inside of the junction tank 121.

[0115] According to this configuration, in addition to the effects of the first embodiment, the following effects are achieved. That is, the first electrolytic solution and the second electrolytic solution merge in the junction tank 121, which promotes homogenization of the hydrogen ion concentrations (pH) of the first electrolytic solution and the second electrolytic solution. Also, the liquid amounts of the first electrolytic solution and the second electrolytic solution are adjusted. This makes it possible to reduce the amount of adjustment performed by the ion concentration adjustment unit 70. Note that, when the hydrogen ion concentrations (pH) of the first electrolytic solution and the second electrolytic solution are homogenized by providing the junction tank 121, the ion concentration adjustment unit 70 may be omitted.

[0116] (Fourth embodiment) Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment in that a natural circulation type AEM water electrolysis apparatus is configured. Note that the configuration other than that described below is the same as that of the first embodiment.

[0117] Fig. 11 is a diagram showing an electrolysis device 1D of a fourth embodiment. Fig. 12 is a cross-sectional view taken along line F11-F11 of the electrolysis device 1D shown in Fig. 11. Fig. 13 is a cross-sectional view taken along line F12-F12 of the electrolysis device 1D shown in Fig. 12.

[0118] As shown in Fig. 11, the electrolysis device 1D is a natural circulation type AEM water electrolysis device. The electrolysis device 1D includes, for example, an electrolysis cell stack 10, a power supply unit 40 (see Fig. 1), an electrolyte supply unit 50D, a sensor unit 60, a concentration liquid volume adjustment unit 70D, and a control device 90 (see Fig. 1).

[0119] Electrolyte solution supply unit 50D has a tank 210, a purification layer 211, a partition plate 212, and first to fourth piping units L1 to L4.

[0120] Tank 210 is, for example, a vertical cylindrical container. Tank 210 is, for example, a pressure-resistant container, and has a pressure resistance of several atmospheres to 800 atmospheres. In this case, high-pressure oxygen and hydrogen can be obtained without using, for example, a compressor. As a result, for example, high-pressure hydrogen can be supplied directly to a fuel tank of a hydrogen vehicle or the like.

[0121] The purification layer 211 is provided at a predetermined distance from the lower end of the tank 210, and is configured to purify the circulating electrolyte. The purification layer 211 is composed of a chelating ion exchange resin having a diameter of, for example, about several mm. In order to fill the chelating ion exchange resin, a support member 211a having a mesh or pores is provided at a predetermined distance from the lower end of the tank 210, and the support member 211a is filled with the chelating ion exchange resin. By passing the electrolyte through this purification layer 211, impurities in the electrolyte can be removed, improving the efficiency of water electrolysis.

[0122] Partition plate 212 hangs down from the upper end of tank 210 and extends in the vertical direction. For example, partition plate 212 extends across the upper and lower ends of tank 210. Partition plate 212 separates the inside of tank 210 into a semicircular first storage section 111 and a semicircular second storage section 112. First storage section 111 is a space that stores a first electrolytic solution. Second storage section 112 is a space that stores a second electrolytic solution.

[0123] In this embodiment, the inside of the tank 210 is separated into the first storage section 111 and the second storage section 112 by a partition plate 212 that separates the tank 210, and it is preferable that the partition plate 212 be in contact with at least the purification layer 211. This is because it is necessary to prevent contact between the oxygen generated in the first storage section 111 and the hydrogen generated in the second storage section 112. Therefore, it is more preferable that the partition plate 212 hangs down to the lower part of the purification layer 211.

[0124] The first piping section L1 connects the first storage section 111 and the electrolytic cell stack 10, and guides the first electrolytic solution contained in the first storage section 111 to the electrolytic cell 11 of the electrolytic cell stack 10. In this embodiment, the first piping section L1 and the electrolytic cell stack 10 are disposed at a position lower than the liquid level of the first electrolytic solution in the first storage section 111. As a result, the first electrolytic solution contained in the first storage section 111 is supplied to the electrolytic cell 11 of the electrolytic cell stack 10 through the first piping section L1 by the hydraulic head pressure of the first electrolytic solution.

[0125] The first electrolytic solution that has passed through the electrolytic cell stack 10 is returned to the first storage unit 111 through the second piping section L2. In this embodiment, the downstream end (the outflow end of the first electrolytic solution) of the second piping section L2 is located in the first electrolytic solution in the first storage unit 111. As a result, the second piping section L2 also has the function of the first gas-liquid separation device 52.

[0126] The third piping section L3 connects the second storage section 112 and the electrolytic cell stack 10, and guides the second electrolytic solution contained in the second storage section 112 to the electrolytic cell stack 10. In this embodiment, the third piping section L3 and the electrolytic cell stack 10 are disposed at a position lower than the liquid level of the second electrolytic solution in the second storage section 112. As a result, the second electrolytic solution contained in the second storage section 112 is supplied to the electrolytic cell stack 10 through the third piping section L3 by the hydraulic head pressure of the second electrolytic solution.

[0127] The second electrolytic solution that has passed through the electrolytic cell stack 10 is returned to the second storage section 112 through the fourth piping section L4. In this embodiment, the downstream end (the outflow end of the second electrolytic solution) of the fourth piping section L4 is located in the second electrolytic solution in the second storage section 112. As a result, the fourth piping section L4 also has the function of the second gas-liquid separation device 57.

[0128] The sensor unit 60 has a first ion concentration sensor 61, a first liquid level sensor 62, a second ion concentration sensor 63, and a second liquid level sensor 64, similarly to the first embodiment.

[0129] (Concentration liquid volume adjustment section) Next, the concentration liquid volume adjusting section 70D will be described. 13, the concentration liquid volume adjustment unit 70D has, for example, a first connection pipe 81A, a second connection pipe 81B, a first pump 83A, and a second pump 83B. The concentration liquid volume adjustment unit 70D is an example of an "ion concentration adjustment unit" and a "liquid volume adjustment unit."

[0130] The first connection pipe 81A is a bypass pipe for moving a portion of the first electrolytic solution contained in the first storage portion 111 to the second storage portion 112. One end of the first connection pipe 81A is connected to the first storage portion 111 in the tank 210. The other end of the first connection pipe 81A is connected to the second storage portion 112 in the tank 210. The first connection pipe 81A is an example of a "first connection portion."

[0131] The first pump 83A is provided in the middle of the first connection pipe 81A. When the first pump 83A is driven, a part of the first electrolytic solution contained in the first storage unit 111 moves to the second storage unit 112 through the first connection pipe 81A. The part of the first electrolytic solution moving from the first storage unit 111 to the second storage unit 112 is an example of an "adjustment solution for adjusting hydrogen ion concentration (pH)". The driving state of the first pump 83A is controlled based on a control signal from the control device 90, which will be described later. As a result, as the electrolysis progresses, a part of the first electrolytic solution that is diluted can be moved to the second storage unit 112 to homogenize the ion concentration.

[0132] In addition, if the liquid level of the first electrolytic solution becomes higher than the liquid level of the second electrolytic solution as the electrolysis progresses, the first pump 83A may be omitted, and a portion of the first electrolytic solution contained in the first storage section 111 may move to the second storage section 112 through the first connection pipe 81A due to the head pressure corresponding to the difference between the liquid level of the first electrolytic solution and the liquid level of the second electrolytic solution.

[0133] The second connection pipe 81B is a bypass pipe for moving a portion of the second electrolytic solution contained in the second storage portion 112 to the first storage portion 111. One end of the second connection pipe 81B is connected to the second storage portion 112 in the tank 210. The other end of the second connection pipe 81B is connected to the first storage portion 111 in the tank 210. The second connection pipe 81B is an example of a "second connection portion."

[0134] The second pump 83B is provided in the middle of the second connection pipe 81B. When the second pump 83B is driven, a part of the second electrolytic solution contained in the second storage unit 112 moves to the first storage unit 111 through the second connection pipe 81B. The part of the second electrolytic solution moving from the second storage unit 112 to the first storage unit 111 is an example of an "adjustment solution for adjusting hydrogen ion concentration (pH)". The driving state of the second pump 83B is controlled based on a control signal from the control device 90, which will be described later. As a result, as the electrolysis progresses, a part of the concentrated second electrolytic solution can be moved to the first storage unit 111 to homogenize the ion concentration.

[0135] As shown in FIG. 12, the concentration liquid amount adjusting unit 70D has a tank 75 and a valve 76. The tank 75 contains an electrolyte (pure water or alkaline aqueous solution) for replenishing the electrolyte consumed as electrolysis proceeds. The electrolyte contained in the tank 75 is an example of an "adjustment liquid for adjusting hydrogen ion concentration (pH)". The valve 76 is provided in the middle of the piping L5 connecting the tank 71 and the tank 210. The valve 76 can be switched between an open state in which the electrolyte contained in the tank 75 passes toward the tank 210 and a closed state in which the electrolyte contained in the tank 75 is prevented from passing toward the tank 210. The valve 76 is switched between an open state and a closed state based on a control signal from a control device 90 described later.

[0136] (Control device) Next, the control device 90 will be described. The control device 90 controls the adjustment operation of the hydrogen ion concentration (pH) by the concentration liquid amount adjuster 70D based on, for example, the detection results of the ion concentration sensors 61, 63 or the liquid level sensors 62, 64 described later. For example, when the detection result of the first ion concentration sensor 61 is less than the threshold value Th11 (when the second electrolytic solution is diluted to a predetermined standard or more), the control device 90 drives the second pump 83B to move a part of the second electrolytic solution contained in the second storage unit 112 to the first storage unit 111. This increases the hydrogen ion concentration (pH) of the first electrolytic solution. Note that instead of / in addition to the above, the control device 90 may drive the second pump 83B to move a part of the second electrolytic solution contained in the second storage unit 112 to the first storage unit 111 when the detection result of the first liquid level sensor 62 is equal to or greater than the threshold value Th21 (when the second electrolytic solution is diluted to a predetermined standard or more).

[0137] On the other hand, when the detection result of the second ion concentration sensor 63 is equal to or higher than the threshold value Th12 (when concentrated to a predetermined standard or higher), the control device 90 drives the first pump 83A to move a portion of the first electrolytic solution contained in the first storage unit 111 to the second storage unit 112. This reduces the hydrogen ion concentration (pH) of the second electrolytic solution. Alternatively / in addition to the above, the control device 90 may drive the first pump 83A to move a portion of the first electrolytic solution contained in the first storage unit 111 to the second storage unit 112 when the detection result of the second liquid level sensor 64 is less than the threshold value Th22.

[0138] Furthermore, instead of / in addition to the above control example, the control device 90 may perform the following control. That is, when the difference between the detection result of the first ion concentration sensor 61 and the detection result of the second ion concentration sensor 63 exceeds a threshold value, the control device 90 may drive the first pump 83A and the second pump 83B to move a part of the first electrolytic solution contained in the first storage unit 111 to the second storage unit 112 and move a part of the second electrolytic solution contained in the second storage unit 112 to the first storage unit 111.

[0139] Furthermore, when the consumption amount of the electrolyte exceeds a preset threshold based on the detection result of the first level sensor 82 or the second level sensor 84, the control device 90 controls the valve 76 to an open state, thereby passing the electrolyte contained in the tank 75 toward the tank 210. This replenishes the consumed electrolyte.

[0140] (Modification of the fourth embodiment) Next, a modification of the fourth embodiment will be described. 14 is a cross-sectional view showing an electrolysis device 1D according to a modification of the fourth embodiment. In this modification, a part or the whole of the partition plate 212 is formed of a diaphragm 113. The diaphragm 113 is provided, for example, at the lower part of the partition plate 212.

[0141] The diaphragm 113 is disposed between the first storage unit 111 and the second storage unit 112 and allows at least one of ions and water (e.g., both) to move between the first storage unit 111 and the second storage unit 112. The material of the diaphragm 113 is not particularly limited as long as it allows at least one of ions and water (e.g., both) to move while preventing mixing of oxygen contained in the first electrolytic solution and hydrogen contained in the second electrolytic solution. The diaphragm 113 is, for example, a diaphragm for alkaline water electrolysis. Specific examples of the diaphragm 113 are as described above in the second embodiment.

[0142] When the diaphragm 113 has ion permeability, ions move between the first and second electrolytic solutions, and the difference in hydrogen ion concentration (pH) between the first and second electrolytic solutions becomes smaller (e.g., becomes homogenized). That is, the hydrogen ion concentration (pH) of the second electrolytic solution decreases, while the hydrogen ion concentration (pH) of the first electrolytic solution increases.

[0143] When the diaphragm 113 is liquid permeable, water moves between the first electrolytic solution and the second electrolytic solution, and the difference in the liquid volume between the first electrolytic solution and the second electrolytic solution becomes smaller (e.g., homogenized). That is, the liquid volume of the first electrolytic solution decreases, while the liquid volume of the second electrolytic solution increases. In this modification, the first connection pipe 81A, the second connection pipe 81B, the first pump 83A, the second pump 83B, etc. may be omitted.

[0144] (Other embodiments) Several embodiments and modifications have been described above. However, the embodiments and modifications are not limited to the above examples. For example, the adjustment of the hydrogen ion concentration (pH) by the first adjustment unit 70A and the second adjustment unit 70B may be performed at a predetermined cycle instead of when the detection result of the sensor satisfies a predetermined condition. In this case, the adjustment amount of the hydrogen ion concentration (pH) by the first adjustment unit 70A and the second adjustment unit 70B may be determined based on the detection result of one or more sensors included in the sensor unit 60.

[0145] <Additional Notes> The electrolysis device described in each embodiment can be understood, for example, as follows.

[0146] (1) The electrolysis device 1, 1A, 1B, 1C, 1D according to the first embodiment includes an electrolysis cell 11, an electrolyte supply unit 50, and an ion concentration adjustment unit 70. The electrolysis cell 11 includes an anode chamber Sa, a cathode chamber Sb, and an ion exchange membrane 31 disposed between the anode chamber Sa and the cathode chamber Sb. The electrolyte supply unit 50 includes at least one tank (e.g., electrolyte tanks 51, 56, joint tank 110, or confluence tank 121) that contains an electrolyte, and circulates a part of the electrolyte between the at least one tank and the anode chamber Sa as a first electrolyte, and circulates another part of the electrolyte between the at least one tank and the cathode chamber Sb as a second electrolyte. The ion concentration adjustment unit 70 supplies an adjustment solution for adjusting a hydrogen ion concentration (pH) to the electrolyte supply unit 50. According to this configuration, when the hydrogen ion concentration (pH) of the electrolyte solution changes due to passing through the electrolytic cell 11, the hydrogen ion concentration (pH) of the electrolyte solution can be maintained within a certain range by adding the adjusting solution to the electrolyte solution, thereby suppressing changes in the electrical conductivity of the electrolyte solution and suppressing deterioration in the performance of the electrolytic device.

[0147] (2) The electrolysis device 1, 1A, 1B, 1C, 1D according to the second aspect is the electrolysis device of (1), further comprising a sensor (for example, a first ion concentration sensor 61, a first liquid level sensor 62, a second ion concentration sensor 63, or a second liquid level sensor 64) for detecting a value related to the hydrogen ion concentration (pH) or the liquid volume of the electrolytic solution, and the ion concentration adjustment unit 70 supplies the adjustment liquid to the electrolytic solution supply unit 50 when the detection result of the above sensor satisfies a predetermined condition. With this configuration, the hydrogen ion concentration (pH) of the electrolytic solution can be adjusted at a timing suitable for the change in the hydrogen ion concentration (pH) or with an adjustment amount suitable for the change in the hydrogen ion concentration (pH) based on the detection result of the sensor for detecting the value related to the hydrogen ion concentration (pH) or the liquid volume of the electrolytic solution. This makes it possible to maintain the hydrogen ion concentration (pH) of the electrolytic solution within a certain range with higher accuracy.

[0148] (3) The electrolysis device 1, 1A, 1B, 1C according to the third aspect is the electrolysis device of (1) or (2), in which the adjusting solution includes a first adjusting solution for increasing the hydrogen ion concentration (pH) and a second adjusting solution for decreasing the hydrogen ion concentration (pH), and the ion concentration adjusting unit 70 has a first adjusting unit 70A that supplies the first adjusting solution to the electrolyte supply unit 50 and a second adjusting unit 70B that supplies the second adjusting solution to the electrolyte supply unit 50. With this configuration, the hydrogen ion concentration (pH) can be adjusted in a direction that suppresses the change in both the electrolyte change in the direction of increasing the hydrogen ion concentration (pH) and the electrolyte change in the direction of decreasing the hydrogen ion concentration (pH). This makes it possible to maintain the hydrogen ion concentration (pH) of the electrolyte within a certain range with higher accuracy.

[0149] (4) The electrolysis device 1, 1A, 1B, 1C according to the fourth aspect is the electrolysis device of (3), in which the first adjustment unit 70A supplies the first adjustment liquid to a first portion (e.g., the first electrolyte tank 51, the first piping section L1, or the second piping section L2) in which the first electrolyte is contained or through which the first electrolyte flows in the electrolyte supply unit 50, and the second adjustment unit 70B supplies the second adjustment liquid to a second portion (e.g., the second electrolyte tank 56, the third piping section L3, or the fourth piping section L4) in which the second electrolyte is contained or through which the second electrolyte flows in the electrolyte supply unit 50. With this configuration, the first adjustment liquid can be used to adjust the first electrolyte having a low hydrogen ion concentration (pH), and the second adjustment liquid can be used to adjust the second electrolyte having a high hydrogen ion concentration (pH). This allows the hydrogen ion concentration (pH) of the electrolyte to be kept within a certain range with higher accuracy.

[0150] (5) The electrolysis device 1, 1A according to a fifth aspect is the electrolysis device of (4), in which the sensor includes a first sensor (e.g., a first ion concentration sensor 61 or a first liquid level sensor 62) for detecting a value related to the hydrogen ion concentration (pH) or the liquid volume of the first electrolytic solution, and a second sensor (e.g., a second ion concentration sensor 63 or a second liquid level sensor 64) for detecting a value related to the hydrogen ion concentration (pH) or the liquid volume of the second electrolytic solution, and the first adjustment unit 70A supplies a first adjustment liquid to the first part of the electrolytic solution supply unit 50 when the detection result of the first sensor satisfies a first predetermined condition, and the second adjustment unit 70B supplies a second adjustment liquid to the second part of the electrolytic solution supply unit 50 when the detection result of the second sensor satisfies a second predetermined condition. With this configuration, the first electrolytic solution can be adjusted based on the detection result of the sensor related to the first electrolytic solution, and the second electrolytic solution can be adjusted based on the detection result of the sensor related to the second electrolytic solution. This makes it possible to maintain the hydrogen ion concentration (pH) of the electrolyte within a certain range with greater precision.

[0151] (6) The electrolysis device 1, 1A according to the sixth aspect is any one of the electrolysis devices (3) to (5), and the at least one tank includes a first tank (e.g., a first electrolytic solution tank 51) that contains a first electrolytic solution and a second tank (e.g., a second electrolytic solution tank 56) that contains a second electrolytic solution, the electrolytic solution supply unit 50 includes a first flow path unit (e.g., a second piping unit L2) that guides the first electrolytic solution that has passed through the anode chamber Sa to the first tank, and a second flow path unit (e.g., a fourth piping unit L4) that guides the second electrolytic solution that has passed through the cathode chamber Sb to the second tank, the first adjustment unit 70A supplies the first adjustment solution to the first flow path unit, and the second adjustment unit 70B supplies the second adjustment solution to the second flow path unit. According to this configuration, the first adjustment solution is added to the first electrolytic solution and the second adjustment solution is added to the second electrolytic solution at a position upstream of the first tank and the second tank. Therefore, the first electrolytic solution and the first adjustment solution flow into the first tank and are thoroughly mixed in the first tank, and then are supplied to the anode chamber Sa of the electrolytic cell 11. Similarly, the second electrolytic solution and the second adjustment solution flow into the second tank and are thoroughly mixed in the second tank, and then are supplied to the cathode chamber Sb of the electrolytic cell 11. Therefore, the hydrogen ion concentration (pH) of the electrolytic solution can be maintained within a certain range with higher accuracy than, for example, when an adjustment solution is added to the electrolytic solution in the first piping section L1 or the third piping section L3.

[0152] (7) The electrolysis device 1, 1A according to the seventh aspect is any one of the electrolysis devices (1) to (6), and further includes a liquid amount adjusting unit 80 that adjusts the amount of the electrolytic solution, and the at least one tank includes a first tank (e.g., the first electrolytic solution tank 51) that contains a first electrolytic solution and a second tank (e.g., the second electrolytic solution tank 56) that contains a second electrolytic solution, and the liquid amount adjusting unit 80 includes a connection unit (e.g., a connection pipe 81) that transfers a part of the first electrolytic solution contained in the first tank to the second tank, or a discharge unit (e.g., a discharge pipe 85) that discharges a part of the second electrolytic solution contained in the first tank to the outside. With this configuration, the amount of the first electrolytic solution that increases as the electrolysis progresses can be appropriately reduced.

[0153] (8) The electrolysis device 1B according to the eighth aspect is any one of the electrolysis devices (1) to (5), in which the at least one tank includes a joint tank 110, and the joint tank 110 has a first storage section 111 for storing a first electrolytic solution, a second storage section 112 for storing a second electrolytic solution, and a membrane disposed between the first storage section 111 and the second storage section 112 and allowing at least one of ions and water to move between the first storage section 111 and the second storage section 112. With this configuration, at least one of the hydrogen ion concentration (pH) and the liquid volume of the electrolytic solution can be adjusted inside the joint tank 110. This makes it possible to adjust the hydrogen ion concentration (pH) and / or the liquid volume of the electrolytic solution more efficiently than when the first electrolytic solution tank 51 and the second electrolytic solution tank 56 are separate.

[0154] (9) The electrolysis device 1B according to a ninth aspect is the electrolysis device according to (8), in which the adjusting solution includes a first adjusting solution for increasing the hydrogen ion concentration (pH) and a second adjusting solution for decreasing the hydrogen ion concentration (pH), the electrolysis solution supply unit 50 has a first flow path section (e.g., the second piping section L2) that guides the first electrolysis solution that has passed through the anode chamber Sa to the first storage section 111, and a second flow path section (e.g., the fourth piping section L4) that guides the second electrolysis solution that has passed through the cathode chamber Sb to the second storage section 112, and the ion concentration adjusting unit 70 has a first adjusting unit 70A that supplies the first adjusting solution to the first flow path section and a second adjusting unit 70B that supplies the second adjusting solution to the second flow path section. According to this configuration, the first adjusting solution is added to the first electrolysis solution and the second adjusting solution is added to the second electrolysis solution at a position upstream of the joint tank 110. Therefore, the first electrolytic solution and the first adjustment solution flow into the joint tank 110 and are thoroughly mixed in the joint tank 110, and then are supplied to the anode chamber Sa of the electrolytic cell 11. Similarly, the second electrolytic solution and the second adjustment solution flow into the joint tank 110 and are thoroughly mixed in the joint tank 110, and then are supplied to the cathode chamber Sb of the electrolytic cell 11. Therefore, the hydrogen ion concentration (pH) of the electrolytic solution can be maintained within a certain range with higher accuracy than, for example, when an adjustment solution is added to the electrolytic solution in the first piping section L1 or the third piping section L3.

[0155] (10) An electrolysis device 1C according to a tenth aspect is the electrolysis device 1C of any one of (1) to (5), wherein the at least one tank includes a junction tank 121 that accommodates at least a part of the first electrolytic solution and at least a part of the second electrolytic solution by merging them together, and the ion concentration adjustment unit 70 supplies an adjustment solution to the junction tank 121. According to this configuration, the hydrogen ion concentration (pH) and the liquid volume of the electrolytic solution are adjusted inside the junction tank 121. This makes it possible to adjust the hydrogen ion concentration (pH) and the liquid volume of the electrolytic solution more efficiently than when the junction tank 121 is not provided.

[0156] (11) The electrolysis device 1C according to an eleventh aspect is the electrolysis device 1C of (10), wherein the at least one tank further includes a first tank (e.g., a first electrolytic solution tank 51) arranged upstream of the junction tank 121 in the flow direction of the liquid and accommodating a first electrolytic solution, and a second tank (e.g., a second electrolytic solution tank 56) arranged upstream of the junction tank 121 in the flow direction of the electrolytic solution and accommodating a second electrolytic solution, wherein the first electrolytic solution flows into the junction tank 121 from the first tank and the second electrolytic solution flows into the junction tank 121 from the second tank, and the electrolytic solution supply unit 50 further includes a first gas-liquid separation unit (e.g., an oxygen gas-liquid separation device 122) arranged between the first tank and the junction tank 121, and a second gas-liquid separation unit (e.g., a hydrogen gas-liquid separation device 123) arranged between the second tank and the junction tank 121. According to such a configuration, the oxygen contained in the first electrolytic solution and the oxygen contained in the second electrolytic solution inside junction tank 121 can be more reliably prevented from mixing.

[0157] (12) The electrolysis device 1D according to a twelfth aspect is the electrolysis device 1D according to (1) or (2), in which the at least one tank includes one tank 210, and the electrolytic solution supply unit 50D has a partition (e.g., a partition plate 212) that divides the inside of the tank 210 into a first storage unit 111 that stores a first electrolytic solution and a second storage unit 112 that stores a second electrolytic solution, and a first connection unit (e.g., a first connection pipe 81A) that is connected to the tank 210 and guides a part of the first electrolytic solution stored in the first storage unit 111 to the second storage unit 112 as the adjustment solution. With this configuration, the concentration of the concentrated second electrolytic solution can be reduced by using a part of the diluted first electrolytic solution.

[0158] (13) The electrolysis device 1D according to a thirteenth aspect is the electrolysis device 1D of (12), which has a purification layer 211 provided in the tank 210 and is a natural circulation type device that purifies the electrolytic solution to be supplied to the electrolytic cell 11 while naturally circulating the electrolytic solution between the electrolytic cell 11 and the tank 210. With this configuration, the electrolytic solution purified by the purification layer 211 can be supplied to the electrolytic cell 11, and the power required for circulating the electrolytic solution can be reduced.

[0159] (14) The electrolysis device 1D according to a fourteenth aspect is the electrolysis device 1D of (12), in which the electrolytic solution supply unit 50D has a second connection unit (e.g., second connection pipe 81B) that is connected to the tank 210 and guides a part of the second electrolytic solution contained in the second storage unit 112 to the first storage unit 111 as the adjusted solution. With this configuration, the concentration of the diluted first electrolytic solution can be increased by using a part of the concentrated second electrolytic solution.

[0160] (15) An electrolysis device 1B according to a fifteenth aspect includes an electrolysis cell 11 and an electrolysis solution supply unit 50. The electrolysis cell 11 includes an anode chamber Sa, a cathode chamber Sb, and an ion exchange membrane 31 disposed between the anode chamber Sa and the cathode chamber Sb. The electrolysis solution supply unit 50 includes a joint tank 110 that accommodates an electrolysis solution, and circulates a part of the electrolysis solution between the joint tank 110 and the anode chamber Sa as a first electrolysis solution, and circulates another part of the electrolysis solution between the joint tank 110 and the cathode chamber Sb as a second electrolysis solution. The joint tank 110 includes a first storage unit 111 that accommodates the first electrolysis solution, a second storage unit 112 that accommodates the second electrolysis solution, and a membrane (e.g., a diaphragm 113) that is disposed between the first storage unit 111 and the second storage unit 112 and allows at least one of ions and water to move between the first storage unit 111 and the second storage unit 112. With this configuration, at least one of the hydrogen ion concentration (pH) and the liquid volume of the electrolyte can be adjusted inside the joint tank 110. This makes it possible to adjust the hydrogen ion concentration (pH) and / or the liquid volume of the electrolyte more efficiently than when the first electrolyte tank 51 and the second electrolyte tank 56 are separate.

[0161] (16) An electrolysis device 1C according to a sixteenth aspect includes an electrolysis cell 11 and an electrolytic solution supply unit 50. The electrolytic cell 11 includes an anode chamber Sa, a cathode chamber Sb, and an ion exchange membrane 31 disposed between the anode chamber Sa and the cathode chamber Sb. The electrolytic solution supply unit 50 includes at least one tank for accommodating an electrolytic solution, and circulates a part of the electrolytic solution between the at least one tank and the anode chamber Sa as a first electrolytic solution, and circulates another part of the electrolytic solution between the at least one tank and the cathode chamber Sb as a second electrolytic solution. The at least one tank includes a junction tank 121 that accommodates the first electrolytic solution and the second electrolytic solution by merging them together. The electrolytic solution supply unit 50 supplies a part of the electrolytic solution accommodated in the junction tank 121 to the anode chamber Sa as the first electrolytic solution, and supplies another part of the electrolytic solution accommodated in the junction tank 121 to the cathode chamber Sb as the second electrolytic solution. According to this configuration, the hydrogen ion concentration (pH) and the liquid volume of the electrolyte are adjusted inside the junction tank 121. This makes it possible to adjust the hydrogen ion concentration (pH) and the liquid volume of the electrolyte more efficiently than when the junction tank 121 is not provided. [Industrial Applicability]

[0162] The present disclosure relates to an electrolysis device that generates hydrogen by electrolyzing water or an alkaline aqueous solution contained in an electrolytic solution, for example. According to the present disclosure, it is possible to suppress a deterioration in the performance of the electrolysis device. [Explanation of symbols]

[0163] 1,1A,1B,1C,1D…Electrolyzer 11…Electrolytic cell Sa: Anode chamber Sb…Cathode chamber 31...Ion exchange membrane 50...Electrolyte supply section 51…First electrolyte tank L1…First piping section L2: Second piping section (first flow path section) 56…Second electrolyte tank L3: Third piping section L4: 4th piping section (2nd flow path section) 60…Sensor section 61...First ion concentration sensor 62…First liquid level sensor 63…Second ion concentration sensor 64…Second liquid level sensor 70…Ion concentration adjustment section 70A…1st adjustment section 70B…Second adjustment section 80...Liquid volume adjustment section 81, 81A, 81B...Connection pipes (connection parts) 85...Discharge piping (discharge part) 110…Joint Tank 111…First storage section 112…Second storage section 113...Diaphragm (membrane) 121…Merge tank 122...Oxygen gas-liquid separator (first gas-liquid separation section) 123...Hydrogen gas-liquid separator (second gas-liquid separation section) 210…Tank 212…Partition

Claims

1. an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber; an electrolyte supply unit having at least one tank for accommodating an electrolyte, circulating a portion of the electrolyte between the at least one tank and the anode chamber as a first electrolyte, and circulating another portion of the electrolyte between the at least one tank and the cathode chamber as a second electrolyte; an ion concentration adjusting unit that supplies an adjusting solution for adjusting a hydrogen ion concentration (pH) to the electrolyte supply unit; Equipped with the at least one tank comprises a joint tank; The combined tank is an electrolysis device having a first storage section that stores the first electrolytic solution, a second storage section that stores the second electrolytic solution, and a membrane that is disposed between the first storage section and the second storage section and allows at least one of ions and water to move between the first storage section and the second storage section.

2. the adjusting solution includes a first adjusting solution for increasing the hydrogen ion concentration (pH) and a second adjusting solution for decreasing the hydrogen ion concentration (pH); the electrolytic solution supply unit has a first flow path portion that guides the first electrolytic solution that has passed through the anode chamber to the first storage unit, and a second flow path portion that guides the second electrolytic solution that has passed through the cathode chamber to the second storage unit, the ion concentration adjusting unit has a first adjusting unit that supplies the first adjusting liquid to the first flow path portion, and a second adjusting unit that supplies the second adjusting liquid to the second flow path portion.

2. The electrolysis device according to claim 1.

3. An electrolytic cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber; an electrolyte supply unit having at least one tank for accommodating an electrolyte, circulating a portion of the electrolyte between the at least one tank and the anode chamber as a first electrolyte, and circulating another portion of the electrolyte between the at least one tank and the cathode chamber as a second electrolyte; an ion concentration adjusting unit that supplies an adjusting solution for adjusting a hydrogen ion concentration (pH) to the electrolyte supply unit; Equipped with The at least one tank comprises one tank, The electrolytic device includes a partition that divides the inside of the tank into a first storage section that stores the first electrolytic solution and a second storage section that stores the second electrolytic solution, and a first connection section that is connected to the tank and guides a portion of the first electrolytic solution stored in the first storage section to the second storage section as the adjustment solution.

4. the electrolysis device is a natural circulation type device having a purification layer provided in the tank and purifying the electrolytic solution to be supplied to the electrolytic cell while naturally circulating the electrolytic solution between the electrolytic cell and the tank; 4. The electrolysis device according to claim 3.

5. The electrolytic solution supply unit has a second connection part connected to the tank and configured to guide a part of the second electrolytic solution contained in the second container to the first container as the adjusting solution.

4. The electrolysis device according to claim 3.

6. Further, a sensor for detecting a value related to a hydrogen ion concentration (pH) or a liquid amount of the electrolyte is provided. The ion concentration adjusting unit supplies the adjusting solution to the electrolyte supply unit when a detection result of the sensor satisfies a predetermined condition.

4. The electrolysis device according to claim 1 or 3.

7. the adjusting solution includes a first adjusting solution for increasing the hydrogen ion concentration (pH) and a second adjusting solution for decreasing the hydrogen ion concentration (pH); The ion concentration adjusting unit has a first adjusting unit that supplies the first adjusting liquid to the electrolyte supply unit, and a second adjusting unit that supplies the second adjusting liquid to the electrolyte supply unit.

4. The electrolysis device according to claim 1 or 3.

8. The first adjustment unit supplies the first adjustment liquid to a first portion of the electrolytic solution supply unit that contains the first electrolytic solution or through which the first electrolytic solution flows, The second adjustment unit supplies the second adjustment liquid to a second portion of the electrolytic solution supply unit that contains the second electrolytic solution or through which the second electrolytic solution flows.

8. The electrolysis device according to claim 7.

9. A first sensor for detecting a value related to a hydrogen ion concentration (pH) or a liquid amount of the first electrolytic solution; A second sensor for detecting a value related to a hydrogen ion concentration (pH) or a liquid amount of the second electrolytic solution; Further equipped with The first adjustment unit supplies the first adjustment liquid to the first portion of the electrolyte supply unit when a detection result of the first sensor satisfies a first predetermined condition, The second adjustment unit supplies the second adjustment liquid to the second portion of the electrolyte supply unit when a detection result of the second sensor satisfies a second predetermined condition.

9. The electrolysis device according to claim 8.

10. The at least one tank includes a first tank containing the first electrolytic solution and a second tank containing the second electrolytic solution; the electrolytic solution supply unit has a first flow path portion that guides the first electrolytic solution that has passed through the anode chamber to the first tank, and a second flow path portion that guides the second electrolytic solution that has passed through the cathode chamber to the second tank, The first adjustment unit supplies the first adjustment liquid to the first flow path unit, The second adjustment unit supplies the second adjustment liquid to the second flow path unit.

9. The electrolysis device according to claim 8.

11. The liquid amount adjusting unit adjusts the amount of the electrolyte. The at least one tank includes a first tank containing the first electrolytic solution and a second tank containing the second electrolytic solution; The liquid amount adjusting unit has a connection unit that moves a portion of the first electrolytic solution contained in the first tank to the second tank, or a discharge unit that discharges a portion of the first electrolytic solution contained in the first tank to the outside.

4. The electrolysis device according to claim 1 or 3.

12. The at least one tank includes a junction tank that accommodates at least a portion of the first electrolytic solution and at least a portion of the second electrolytic solution in a junction state, The ion concentration adjusting unit supplies the adjusting solution to the confluence tank.

4. The electrolysis device according to claim 1 or 3.

13. the at least one tank further includes a first tank arranged upstream of the junction tank in the flow direction of the electrolyte and accommodating the first electrolyte, and a second tank arranged upstream of the junction tank in the flow direction of the electrolyte and accommodating the second electrolyte, wherein the first electrolyte flows into the junction tank from the first tank and the second electrolyte flows into the junction tank from the second tank, the electrolytic solution supply unit further includes a first gas-liquid separation unit disposed between the first tank and the junction tank, and a second gas-liquid separation unit disposed between the second tank and the junction tank; 13. The electrolysis device according to claim 12.

14. an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber; an electrolyte supply unit having a joint tank for storing an electrolyte, circulating a part of the electrolyte between the joint tank and the anode chamber as a first electrolyte, and circulating another part of the electrolyte between the joint tank and the cathode chamber as a second electrolyte; Equipped with the combined tank has a first storage section that stores the first electrolytic solution, a second storage section that stores the second electrolytic solution, and a membrane that is disposed between the first storage section and the second storage section and allows at least one of ions and water to move between the first storage section and the second storage section; The joint tank includes one tank, The electrolytic device includes a partition that divides the inside of the tank into the first storage section that stores the first electrolytic solution and the second storage section that stores the second electrolytic solution, and a first connection section that is connected to the tank and guides a portion of the first electrolytic solution stored in the first storage section to the second storage section as an adjusting solution.

15. an electrolysis cell having an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber; an electrolyte supply unit having at least one tank for accommodating an electrolyte, circulating a portion of the electrolyte between the at least one tank and the anode chamber as a first electrolyte, and circulating another portion of the electrolyte between the at least one tank and the cathode chamber as a second electrolyte; Equipped with The at least one tank includes a junction tank that accommodates at least a portion of the first electrolytic solution and at least a portion of the second electrolytic solution in a junction state, the electrolytic solution supply unit supplies a portion of the electrolytic solution contained in the junction tank to the anode chamber as the first electrolytic solution, and supplies another portion of the electrolytic solution contained in the junction tank to the cathode chamber as the second electrolytic solution, the at least one tank comprises a joint tank; The combined tank is an electrolysis device having a first storage section that stores the first electrolytic solution, a second storage section that stores the second electrolytic solution, and a membrane that is disposed between the first storage section and the second storage section and allows at least one of ions and water to move between the first storage section and the second storage section.

16. An electrolytic cell comprising an anode chamber, a cathode chamber, and an ion exchange membrane disposed between the anode chamber and the cathode chamber; an electrolyte supply unit having at least one tank for accommodating an electrolyte, circulating a portion of the electrolyte between the at least one tank and the anode chamber as a first electrolyte, and circulating another portion of the electrolyte between the at least one tank and the cathode chamber as a second electrolyte; Equipped with The at least one tank includes a junction tank that accommodates at least a portion of the first electrolytic solution and at least a portion of the second electrolytic solution in a junction state, the electrolytic solution supply unit supplies a portion of the electrolytic solution contained in the junction tank to the anode chamber as the first electrolytic solution, and supplies another portion of the electrolytic solution contained in the junction tank to the cathode chamber as the second electrolytic solution, The at least one tank comprises one tank, The electrolytic device includes a partition that divides the inside of the tank into a first storage section that stores the first electrolytic solution and a second storage section that stores the second electrolytic solution, and a first connection section that is connected to the tank and guides a portion of the first electrolytic solution stored in the first storage section to the second storage section as an adjusting solution.

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