JP2013028822A - Apparatus and method for electrolyzing alkaline water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline water electrolytic apparatus that is facilitated in removing bubbles from an electrolytic solution, and to provide an alkaline water electrolytic method.SOLUTION: The alkaline water electrolytic apparatus includes: an anode chamber 20 in which an anode 25 is disposed; a cathode chamber 30 in which a cathode 35 is disposed; a diaphragm 40 for partitioning between the anode chamber 20 and the cathode chamber 30; and an electrolytic bath 10 for electrolyzing the electrolytic solution 80 to produce hydrogen 78. The electrolytic bath 10 is configured such that the electrolytic solution 80 is introduced from a bottom introduction part 26 of the anode chamber 20 and flows upward through the anode chamber 20 toward a top discharging part 28, and the electrolytic solution 80 is introduced from a bottom introduction part 36 of the cathode chamber 30 and flows upward through the cathode chamber 30 toward a top discharging part 38. The electrolytic solution 80 has a pH of 14 or more measured at 27°C, an electrical conductivity of 0.25 S/cm or more measured at 27°C and a density of 1.25 kg/mor more.

Description

  The present invention relates to an alkaline water electrolysis apparatus and an alkaline water electrolysis method for producing hydrogen gas by electrolyzing alkaline water.

  In recent years, power generation using renewable energy such as sunlight, solar heat, and wind power is increasing. However, since renewable energy fluctuates depending on the natural environment, it is difficult to control the output of power generation using renewable energy. For this reason, when the proportion of power generation using renewable energy increases, the power supply-demand balance is disrupted, which tends to cause excess power and power shortage.

  In addition, the output of power generation using renewable energy always repeats slight changes with changes in weather and the like. For this reason, it is difficult to directly connect a power generation facility using renewable energy to the power system.

  As a method of solving the problems of power generation using these renewable energies, a method of converting electric power obtained from renewable energies into other energy that can be stably extracted and storing it, for example, by a battery Methods such as power storage, pumped-storage power generation, and hydrogen power storage are being studied. Here, hydrogen power storage is a storage method in which electric power obtained from renewable energy is used for electrolysis of water and stored as generated hydrogen.

  Of these, hydrogen power storage is attracting attention as a preferred method for storing electric power because it is not easily restricted by location and heat source, and energy loss does not substantially occur even during long-term storage. Among hydrogen power storage, alkaline water electrolysis, which is electrolysis of water using an alkaline aqueous solution, has a long history and has a long track record, and is regarded as a promising future power storage method.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 3-218901) describes an apparatus that efficiently stores hydrogen by combining a hydrogen generator and a hydrogen storage alloy. Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2010-150590) and Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2009-242922) describe the structure of an electrode for alkaline water electrolysis. Furthermore, Patent Document 4 (Japanese Patent Application Laid-Open No. 2008-45205) describes an electrolytic cell and an electrode that hardly corrode even in an alkaline water electrolysis environment.

JP-A-3-218901 JP 2010-150590 A JP 2009-242922 A JP 2008-45205 A JP 2007-154217 A

  In the electrolysis of water, it is preferable that the contact between the electrolytic solution and the electrode and the movement of electrons contained in the electrolytic solution are sufficiently performed for efficient operation of the water electrolysis apparatus. However, since water and oxygen are generated in the electrolysis of water, bubbles composed of hydrogen, oxygen, and the like exist in the vicinity of the electrode and in the electrolytic solution. If the bubbles prevent the contact between the electrode and the electrolyte and the movement of electrons in the electrolyte, efficient operation of the water electrolysis apparatus becomes difficult.

  In addition, in hydrogen power storage, it is preferable to electrolyze water using the power generated by renewable energy as it is in order to increase energy efficiency. However, when fluctuations in the power used for electrolysis occur due to fluctuations in the output of the power generated by renewable energy, the generation amounts of hydrogen and oxygen change constantly, and the efficiency of the water electrolysis device also changes constantly. For this reason, hydrogen production may be impossible depending on the situation of renewable energy.

  On the other hand, Patent Document 5 (Japanese Patent Application Laid-Open No. 2007-154217) discloses a technique for removing bubbles made of hydrogen, oxygen, etc. from an electrolyte solution, and a liquid channel inside the electrolytic cell and a gas channel for releasing the bubbles. A small electrode is provided in a region of 100 μm or less from the boundary between the gas channel and the liquid channel, and the surface tension between the electrode and the bubble is reduced to further reduce the surface tension between the electrode and the bubble. A method is described in which bubbles are removed from the vicinity of the electrode and the inside of the electrolytic cell by being moved to.

  The electrode described in Patent Document 5 has a very small structure with a length of 100 μm or less in the liquid flow path direction. For example, an electrode formed by bending a platinum foil having a thickness of 10 μm or a platinum having a thickness of 100 μm. An electrode using a plate is described.

  However, since the electrode used in the invention described in Patent Document 5 is very small, it is substantially impossible to produce a very small electrode with a limited electrode material suitable for an alkaline water electrolysis environment. There was a problem that it was difficult.

  The present invention solves the above-described problems, and an object thereof is to provide an alkaline water electrolysis apparatus and an alkaline water electrolysis method that can easily remove bubbles from an electrolytic solution.

  The present invention increases the density of the electrolytic solution to a predetermined value or more to increase the density difference between the electrolytic solution and the gas constituting the bubbles, thereby increasing the rising speed of the bubbles, and the rising direction of the bubbles and the flowing direction of the electrolytic solution. It has been made by finding out that the bubbles can be prevented from staying in the electrolytic cell without having a complicated shape in the electrolytic cell if the above are matched.

That is, the alkaline water electrolysis apparatus of the present invention is for solving the above-described problem, and partitions the anode chamber in which the anode is disposed, the cathode chamber in which the cathode is disposed, and the anode chamber and the cathode chamber. An alkaline water electrolysis apparatus comprising an electrolytic cell having a diaphragm and electrolyzing an electrolytic solution made of a basic aqueous solution to produce hydrogen, wherein the electrolytic cell is introduced from a bottom introduction part of the anode chamber The electrolytic solution is electrolyzed by the anode and the cathode while flowing upward in the anode chamber toward the top discharge portion of the anode chamber to generate an anode chamber liquid and oxygen gas. The anode chamber liquid and oxygen gas are discharged from the top discharge portion, and the electrolyte introduced from the bottom portion introduction portion of the cathode chamber flows upward in the cathode chamber toward the top discharge portion of the cathode chamber. On the way, the anode and the The cathode chamber liquid and hydrogen gas are generated by being electrolyzed with an electrode, and the cathode chamber liquid and hydrogen gas are discharged from the top discharge portion of the cathode chamber. The electrolyte was measured at 27 ° C. The pH is 14 or more, the electrical conductivity measured at 27 ° C. is 0.25 S / cm or more, and the density is 1.25 kg / m ³ or more.

Moreover, the alkaline water electrolysis method of the present invention is for solving the above-mentioned problems, and partitions the anode chamber in which the anode is disposed, the cathode chamber in which the cathode is disposed, and the anode chamber and the cathode chamber. An alkaline water electrolysis method using an alkaline water electrolysis apparatus comprising an electrolytic cell that has a diaphragm and electrolyzes an electrolytic solution made of a basic aqueous solution to produce hydrogen, the electrolytic cell comprising the anode chamber The electrolyte introduced from the bottom introduction portion of the anode is electrolyzed by the anode and the cathode while flowing upward in the anode chamber toward the top discharge portion of the anode chamber, and the anode chamber solution and oxygen gas The anode chamber liquid and oxygen gas are discharged from the top discharge portion of the anode chamber, and the electrolyte introduced from the bottom introduction portion of the cathode chamber is discharged to the top discharge portion of the cathode chamber. Flows upward in the cathode chamber The cathode and the cathode are electrolyzed to produce a cathode chamber liquid and hydrogen gas, and the cathode chamber liquid and hydrogen gas are discharged from the top discharge portion of the cathode chamber, The liquid is characterized in that the pH measured at 27 ° C. is 14 or more, the electrical conductivity measured at 27 ° C. is 0.25 S / cm or more, and the density is 1.25 kg / m ³ or more.

  According to the alkaline water electrolysis apparatus and the alkaline water electrolysis method of the present invention, it is possible to prevent bubbles from staying in the electrolytic cell and increase the electrolysis efficiency of water electrolysis.

  In addition, according to the alkaline water electrolysis apparatus and alkaline water electrolysis method of the present invention, it is possible to prevent bubbles from staying in the electrolytic cell and increase the efficiency of water electrolysis. Even when the current to be fluctuated due to power generation using renewable energy, the water can be efficiently electrolyzed.

The schematic block diagram which shows embodiment of the alkaline water electrolysis apparatus of this invention. The schematic block diagram which shows the electrolytic cell which comprises the alkaline water electrolysis apparatus shown in FIG. The graph which shows the relationship between electrolyte solution density and bubble rising speed. The graph which shows the relationship between K ⁺ density ^| concentration and electrical conductivity. The graph which shows the relationship between the ratio of the density | concentration of K ^<+> and Cs ^<+ >, and electrical conductivity. The graph which shows the relationship between KOH density | concentration and electrolyte solution density. The graph which shows the relationship between the ratio of the density | concentration of K ^<+> and Cs ^<+ >, and electrolyte solution density. The graph which shows the relationship between the ratio of the density | concentration of K ^<+> and Cs ^<+ >, and electrical conductivity. The graph which shows the relationship between the flow volume of electrolyte solution and electrolysis efficiency.

[Alkaline water electrolyzer]
The alkaline water electrolysis apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of the alkaline water electrolysis apparatus of the present invention.
As shown in FIG. 1, the alkaline water electrolysis apparatus 1 includes an electrolytic solution tank 50 that stores an electrolytic solution 80 that is supplied to the electrolytic cell 10, and an electrolytic solution 80 in the electrolytic solution tank 50. Liquid pumps 64, 74 that transfer to the cathode chamber 30, an electrolytic cell 10 that electrolyzes the electrolytic solution 80 to produce hydrogen 78, an anode chamber liquid 81 that is discharged from the anode chamber 20 of the electrolytic cell 10, An anode chamber liquid / gas / liquid separator 66 that separates the oxygen gas 68, and a cathode chamber liquid / gas / liquid separator 76 that separates the cathode chamber liquid 82 and the hydrogen gas 78 discharged from the cathode chamber 30 of the electrolytic cell 10. Prepare.

  Here, the anode chamber liquid 81 means a liquid generated in the anode chamber 20 by electrolyzing the electrolytic solution 80. The cathode chamber liquid 82 means a liquid generated in the cathode chamber 30 by electrolyzing the electrolytic solution 80.

In the electrolysis of the electrolytic solution 80, the oxygen gas 68 is generated from the hydroxide ions OH ⁻ in the electrolytic solution 80 and the hydrogen gas 78 is generated from the hydrogen ions H ⁺ . The diaphragm 40 that separates the anode chamber 20 and the cathode chamber 30 is not an ion-exchange membrane having selectivity for ions, such as a Teflon (registered trademark) diaphragm that cannot transmit bubbles but can transmit electrolyte and water. A diaphragm is used.

For this reason, the composition of the anode chamber solution 81 and the cathode chamber solution 82 is substantially the same as the composition of the electrolyte solution 80 except for the decrease in H ⁺ and OH ⁻ accompanying electrolysis.

  The liquid feed pump 64 is provided in the middle of the anode chamber electrolyte supply system 61 for transferring the electrolyte 80 from the electrolyte tank 50 to the anode chamber 20 of the electrolytic bath 10. A flow meter 65 for measuring 80 flow rates is provided. The liquid feed pump 64 can supply the electrolytic solution from the electrolytic solution tank 50 to the electrolytic cell 10 in an amount more than the consumption amount of the electrolytic solution 80 by electrolysis in the electrolytic cell 10.

  The liquid feed pump 74 is provided in the middle of the cathode chamber electrolyte supply system 71 for transferring the electrolyte 80 from the electrolyte tank 50 to the cathode chamber 30 of the electrolytic cell 10. A flow meter 75 for measuring 80 flow rates is provided. The liquid feed pump 74 can supply the electrolytic solution from the electrolytic solution tank 50 to the electrolytic cell 10 in an amount equal to or more than the consumption amount of the electrolytic solution 80 by electrolysis in the electrolytic cell 10.

  Further, the alkaline water electrolysis apparatus 1 shown in FIG. 1 includes an anode chamber liquid circulation system 63 that transfers the anode chamber liquid 81 discharged from the anode chamber 20 of the electrolytic cell 10 to the electrolyte tank 50, and the cathode chamber of the electrolytic cell 10. And a cathode chamber liquid circulation system 73 for transferring the cathode chamber liquid 82 discharged from 30 to the electrolyte tank 50. An anode chamber liquid / gas / liquid separator 66 is provided in the middle of the anode chamber liquid circulation system 63, and a cathode chamber / liquid / liquid separator 76 is provided in the middle of the cathode chamber liquid circulation system 73.

  With the above configuration, in the alkaline water electrolysis apparatus 1, the anode chamber liquid 81 generated in the anode chamber 20 of the electrolytic cell 10 by electrolysis of the electrolyte 80 and discharged from the anode chamber 20 is oxygenated in the anode chamber liquid circulation system 63. A circulation system is formed which is separated from the gas 68 and then transferred to the electrolyte tank 50. In the alkaline water electrolysis apparatus 1, the cathode chamber liquid 82 generated in the cathode chamber 30 of the electrolytic cell 10 by electrolysis of the electrolyte 80 and discharged from the cathode chamber 30 is hydrogen gas 78 in the cathode chamber liquid circulation system 73. And a circulation system that is transferred to the electrolytic solution tank 50 is formed.

  The oxygen gas 68 separated by the anode chamber liquid gas-liquid separator 66 of the anode chamber liquid circulation system 63 flows through the oxygen gas system 67 and is sent to an oxygen gas storage system (not shown) for storage. The hydrogen gas 78 separated by the cathode chamber liquid / gas / liquid separator 76 of the cathode chamber liquid circulation system 73 flows through the hydrogen gas system 77 and is sent to and stored in a hydrogen gas storage system (not shown).

(Electrolysis tank)
FIG. 2 is a schematic configuration diagram showing an electrolytic cell 10 constituting the alkaline water electrolysis apparatus 1 shown in FIG. The electrolytic cell 10 includes an anode chamber 20 in which an anode 25 is disposed, a cathode chamber 30 in which a cathode 35 is disposed, and a diaphragm 40 that partitions the anode chamber 20 and the cathode chamber 30. The electrolytic solution 80 is electrolyzed to produce hydrogen.

  Specifically, the electrolytic cell 10 shown in FIG. 2 is made of a metal such as stainless steel, and is composed of an anode chamber main body 21 partially formed with an opening and a metal such as stainless steel, and partially opened. And a diaphragm 40 interposed in a portion where the opening of the anode chamber main body 21 and the opening of the cathode chamber main body 31 are overlapped.

  Thereby, in the electrolytic cell 10, the anode chamber 20 partitioned by the anode chamber body 21 and the diaphragm 40 and the cathode chamber 30 partitioned by the cathode chamber body 31 and the diaphragm 40 are adjacent to each other through the single diaphragm 40. It is formed to do.

  The diaphragm 40 used in the electrolytic cell 10 can transmit the electrolytic solution 80, the anode chamber solution 81, and the cathode chamber solution 82, while generating oxygen gas 68 generated in the anode chamber 20 and the cathode chamber 30. Thus, the hydrogen gas 78 cannot be permeated. Therefore, in the electrolytic cell 10, mixing of the oxygen gas 68 generated in the anode chamber 20 and the hydrogen gas 78 generated in the cathode chamber 30 is prevented by the diaphragm 40.

  The diaphragm 40 is permeable to the electrolyte solution 80, the anode chamber solution 81, and the cathode chamber solution 82. Therefore, the diaphragm 40 is not an ion-selective ion exchange membrane, and can transmit electrolyte and water in an aqueous solution. It is a thing. As the diaphragm 40, for example, a Teflon diaphragm is used.

<Anode chamber>
The anode chamber main body 21 constituting the anode chamber 20 of the electrolytic cell 10 is provided at the bottom of the anode chamber main body 21, and includes a bottom introducing portion 26 for introducing the electrolytic solution 80 into the anode chamber 20, and the top of the anode chamber main body 21. And a top discharge part 28 for discharging the anode chamber liquid 81 and the oxygen gas 68 generated by electrolysis of the electrolyte 80 in the anode chamber 20 to the outside of the anode chamber 20.

  The anode chamber 20 of the electrolytic cell 10 includes an anode chamber midstream portion 23 provided with an anode 25, an anode chamber upstream portion 22 located on the bottom introduction portion 26 side of the anode chamber 20 with respect to the anode chamber midstream portion 23, and An anode chamber downstream portion 24 located on the top discharge portion 28 side of the anode chamber 20 relative to the anode chamber midstream portion 23.

[Upstream part of anode chamber]
The upstream portion 22 of the anode chamber substantially has the flow of the electrolytic solution 80 introduced into the anode chamber 20 of the electrolytic cell 10 in the anode chamber 20 before reaching the midstream portion 23 where the anode 25 is provided. This is the part that rectifies so as to be vertically upward. The anode chamber upstream portion 22 functions as a run-up section of the electrolytic solution 80 before electrolysis in the anode chamber midstream portion 23.

  In the anode chamber upstream portion 22, a rectifying plate 27 for arbitrarily controlling the flow direction of the electrolytic solution 80 is disposed in order to rectify the flow of the electrolytic solution 80 substantially vertically upward.

  The rectifying plate 27 rectifies the flow of the electrolyte solution 80 so that the flow is a laminar flow or a flow similar to the laminar flow, and the flow is substantially vertically upward. As the rectifying plate 27, known means are used, for example, a laminate of a plurality of flat or corrugated metal plates.

  The rectifying plate 27 rectifies the flow of the electrolytic solution 80 introduced into the anode chamber 20 substantially vertically upward. However, the flow direction of the electrolytic solution 80 can be arbitrarily controlled. May be. As a method for arbitrarily controlling the flow direction of the electrolytic solution 80, there is a method in which the flow straightening plate 27 is installed in a movable state and the flow direction of the flow straightening plate 27 is controlled.

[Middle part of anode chamber]
The anode chamber midstream portion 23 is a portion of the anode chamber 20 where the anode 25 is provided. The anode 25 is provided in a portion of the inner wall of the anode chamber body 21 that faces the diaphragm 40 and is spaced from the diaphragm 40.

  As a material of the anode 25, a known material used for alkaline water electrolysis is used and is not particularly limited. As a material of the anode 25, for example, iron, an iron-based alloy, nickel, a nickel-based alloy, or the like is used. In the electrolytic cell 10 shown in FIG. 2, one example of the anode 25 is shown. However, the electrolytic cell of the alkaline water electrolysis apparatus of the present invention may be provided with a plurality of anodes 25.

  A voltage is applied from a DC power source (not shown) between the anode 25 and the cathode 35 provided in the cathode chamber 30, and the electrolytic solution 80 is electrolyzed in the anode chamber 20 and the cathode chamber 30 of the electrolytic cell 10. Done.

  Although it does not specifically limit as DC power supply, For example, it is the electric power generating apparatus using renewable energy, such as sunlight, solar heat, a wind force, Comprising: If necessary, what enabled direct current output by rectification etc. is used.

When electrolysis, the current density of the anode 25 is usually 1 A / cm ² or less, preferably 0.1 to 1 A / cm ² , more preferably 0.2 to 0.5 A / cm ² . This is desirable because the hydrogen gas 78 can be efficiently produced by the cathode 35 of the first electrode.

[Downstream part of anode chamber]
The anode chamber downstream portion 24 is a portion of the anode chamber 20 formed in a shape in which the anode chamber liquid 81 and the oxygen gas 68 generated by electrolysis in the anode chamber midstream portion 23 provided with the anode 25 flow upward. is there.

  The anode chamber downstream portion 24 smoothly guides the anode chamber liquid 81 and the oxygen gas 68 generated by the electrolysis to the top discharge portion 28 provided above the anode chamber 20, whereby the anode 25 of the anode chamber midstream portion 23. The flow of the nearby electrolyte 80 is not hindered.

  Specifically, the anode chamber downstream portion 24 is formed in a shape that linearly connects the anode chamber midstream portion 23 and the top discharge portion 28, and the cross-sectional area of the anode chamber liquid 81 in the flow direction is the anode chamber midstream portion. 23 is formed so as to gradually decrease from the middle of 23 toward the top discharge portion 28 side. With such a shape, in the anode chamber downstream portion 24, the anode chamber liquid 81 and the oxygen gas 68 can smoothly flow upward from the anode chamber midstream portion 23 toward the top discharge portion 28 without stagnation. ing.

  With the above configuration, in the anode chamber 20 of the electrolytic cell 10, the electrolytic solution 80 introduced from the bottom introduction portion 26 of the anode chamber 20 is flowing upward in the anode chamber 20 toward the top discharge portion 28 of the anode chamber 20. Thus, the anode 25 and the cathode 35 are electrolyzed to generate the anode chamber liquid 81 and the oxygen gas 68, and the anode chamber liquid 81 and the oxygen gas 68 are smoothly discharged from the top discharge portion 28 of the anode chamber 20. It has become.

<Cathode room>
The cathode chamber main body 31 constituting the cathode chamber 30 of the electrolytic cell 10 is provided at the bottom of the cathode chamber main body 31, and introduces an electrolyte solution 80 into the cathode chamber 30, and a top of the cathode chamber main body 31. And a top discharge part 38 for discharging the cathode chamber liquid 82 and the hydrogen gas 78 generated by electrolysis of the electrolytic solution 80 in the cathode chamber 30 to the outside of the cathode chamber 30.

  The cathode chamber 30 of the electrolytic cell 10 includes a cathode chamber midstream portion 33 provided with a cathode 35, a cathode chamber upstream portion 32 located on the bottom introduction portion 36 side of the cathode chamber 30 with respect to the cathode chamber midstream portion 33, and The cathode chamber downstream portion 34 is located closer to the top discharge portion 38 of the cathode chamber 30 than the cathode chamber midstream portion 33.

[Upstream part of cathode chamber]
The cathode chamber upstream portion 32 substantially causes the flow of the electrolytic solution 80 introduced into the cathode chamber 30 of the electrolytic cell 10 in the cathode chamber 30 before reaching the cathode chamber midstream portion 33 provided with the cathode 35. This is the part that rectifies so as to be vertically upward. The cathode chamber upstream portion 32 functions as a run-up section of the electrolytic solution 80 before electrolysis in the cathode chamber midstream portion 33.

  In the cathode chamber upstream portion 32, a rectifying plate 37 for arbitrarily controlling the flow direction of the electrolytic solution 80 is disposed in order to rectify the flow of the electrolytic solution 80 substantially vertically upward. The rectifying plate 37 provided in the cathode chamber upstream portion 32 has the same structure as the rectifying plate 27 provided in the anode chamber upstream portion 22, and the operation is the same, and thus the description thereof is omitted.

[Middle part of cathode chamber]
The cathode chamber midstream portion 33 is a portion of the cathode chamber 30 where the cathode 35 is provided. The cathode 35 is provided in a portion of the inner wall of the cathode chamber body 31 that faces the diaphragm 40 and is separated from the diaphragm 40. The cathode 35 provided in the cathode chamber midstream portion 33 has the same structure as the anode 25 provided in the anode chamber midstream portion 23 and has the same function, and thus the description thereof is omitted. In the electrolytic cell 10 shown in FIG. 2, an example in which the number of the cathodes 35 is one is shown. However, the electrolytic cell of the alkaline water electrolysis apparatus of the present invention may be provided with a plurality of cathodes 35.

  A voltage is applied from a DC power source (not shown) between the cathode 35 and the anode 25 provided in the anode chamber 20, and the electrolytic solution 80 is electrolyzed in the anode chamber 20 and the cathode chamber 30 of the electrolytic cell 10. Done. The direct current power source used is the same as that explained in the part explaining the anode 25 provided in the anode chamber 20, and therefore the explanation is omitted.

When electrolysis, the current density of the cathode 35 is usually 1 A / cm ² or less, preferably 0.1 to 1 A / cm ² , more preferably 0.2 to 0.5 A / cm ^2. It is desirable because it can be manufactured efficiently.

[Downstream part of cathode chamber]
The cathode chamber downstream portion 34 is a portion of the cathode chamber 30 formed into a shape in which the cathode chamber liquid 82 and hydrogen gas 78 generated by electrolysis in the cathode chamber midstream portion 33 provided with the cathode 35 flow upward. is there.

  The cathode chamber downstream portion 34 smoothly guides the cathode chamber liquid 82 and the hydrogen gas 78 generated by the electrolysis to the top discharge portion 38 provided above the cathode chamber 30, whereby the cathode 35 of the cathode chamber midstream portion 33. The flow of the nearby electrolyte 80 is not hindered.

  Specifically, the cathode chamber downstream portion 34 is formed in a shape that linearly connects the cathode chamber midstream portion 33 and the top discharge portion 38, and the cross-sectional area of the cathode chamber liquid 82 in the flow direction is the cathode chamber midstream portion. It is formed so as to gradually decrease from the middle of 33 toward the top discharge portion 38 side. With such a shape, in the cathode chamber downstream portion 34, the cathode chamber liquid 82 and the hydrogen gas 78 can smoothly flow upward from the cathode chamber midstream portion 33 toward the top discharge portion 38 without stagnation. ing.

  With the above configuration, in the cathode chamber 30 of the electrolytic cell 10, the electrolytic solution 80 introduced from the bottom introduction portion 36 of the cathode chamber 30 is flowing upward in the cathode chamber 30 toward the top discharge portion 38 of the cathode chamber 30. Thus, the cathode chamber liquid 82 and the hydrogen gas 78 are generated by being electrolyzed at the anode 25 and the cathode 35 so that the cathode chamber liquid 82 and the hydrogen gas 78 are smoothly discharged from the top discharge portion 38 of the cathode chamber 30. It has become.

(Electrolyte)
The electrolytic solution 80 used for electrolysis in the alkaline water electrolysis apparatus 1 is an alkaline aqueous solution. The density of the electrolytic solution 80 is controlled by adjusting the type or concentration of the cation in the electrolytic solution 80.

  It is preferable that the electrolytic solution 80 contains potassium hydroxide KOH as an electrolyte because the electrolysis efficiency of water electrolysis is high. Further, it is desirable that the electrolytic solution 80 has a KOH concentration of 4 to 7 mol / kg, preferably 5 to 7 mol / kg, because the electrolysis efficiency of water electrolysis is high.

  When the electrolytic solution 80 contains KOH and an alkali metal hydroxide other than KOH as an electrolyte, the electrolytic efficiency of water electrolysis is increased by the action of increasing the density of the electrolytic solution 80 and increasing the electric conductivity. Is preferable because of high. Here, the alkali metal means Li, Na, K, Rb, Cs, and Fr.

  As the alkali metal hydroxide other than KOH, for example, at least one selected from RbOH and CsOH is used. When the electrolytic solution 80 contains RbOH or CsOH in addition to KOH, the electrolytic efficiency of water electrolysis becomes higher due to the action of increasing the density of the electrolytic solution 80 and increasing the electric conductivity. preferable.

  Moreover, since the electrolytic solution 80 has a high electrolysis efficiency of water electrolysis, the alkali metal concentration is preferably 3 to 8 mol / kg. Here, the concentration of alkali metal means the concentration of alkali metal constituting all alkali metal hydroxides including KOH.

  When the ratio of the KOH content to the alkali metal hydroxide content is usually in the range of 80 to 100% by mass, preferably 80 to 90% by mass, the electrolytic solution 80 has an electrolysis efficiency of water electrolysis. Is desirable because it is high.

  The electrolytic solution 80 has a pH measured at 27 ° C. of 14 or more, preferably 14 to 15, and more preferably 14.5 to 15.

  It is preferable that the pH of the electrolytic solution 80 measured at 27 ° C. is 14 or higher because the electrolytic conductivity of the electrolytic solution 80 is high because the electrolytic conductivity of the electrolytic solution 80 is high.

  Further, the electrolytic solution 80 has an electric conductivity measured at 27 ° C. of 0.25 S / cm or more, preferably 0.25 to 0.5 S / cm, more preferably 0.3 to 0.5 S / cm.

  It is preferable that the electrical conductivity of the electrolytic solution 80 measured at 27 ° C. is 0.25 S / cm or more because the electrolytic efficiency of the electrolytic solution 80 is increased.

Furthermore, the electrolyte solution 80 has a density of 1.25 kg / m ³ or more, preferably 1.25 to 1.5 kg / m ³ , more preferably 1.35 to 1.5 kg / m ³ . Here, the density means a density measured at 27 ° C.

When the density of the electrolytic solution 80 is 1.25 kg / m ³ or more, bubbles including the oxygen gas 68 and the hydrogen gas 78 generated by electrolysis of the electrolytic solution 80, the electrolytic solution 80, the anode chamber liquid 81, or the cathode The density difference from the liquid such as the chamber liquid 82 is increased, and the rising speed of the bubbles is increased. This is preferable because the retention of bubbles in the electrolytic cell 10 can be prevented and the efficiency of water electrolysis can be increased.

  Here, it will be described that as the density of the electrolytic solution 80 increases, the rising speed of bubbles in the electrolytic solution 80 increases. In addition, when the electrolyte 80 has a flow, a method for further increasing the bubble rising speed is also examined.

First, the bubble rising speed v _f when the flow of the electrolytic solution 80 does not exist in the electrolytic cell 10, that is, the bubble rising speed v _f due to the bubble buoyancy is calculated. The rising speed v _f of the bubble due to the buoyancy of the bubble is expressed by the following formula (1). In addition, the buoyancy F of the following formula (1) is calculated using the following formula (2).

From the equations (1) and (2), when the density ρ _l of the electrolytic solution 80 is increased and the density difference between the density ρ _l of the electrolytic solution 80 and the gas ρ _g constituting the bubbles is increased, the bubble rising speed v It can be seen that _f increases.

FIG. 3 is a graph showing the relationship between the electrolyte density and the bubble rising speed. FIG. 3 shows the rising speed of bubbles generated during electrolysis of the alkaline electrolyte. Specifically, the gas volume (bubble volume) V, the bubble mass m, and the gas density (bubble density) ρ. The bubble rising speed v _f when bubbles having the same _g rise in electrolytes having various liquid densities ρ ₁ is calculated from the equations (1) and (2). In FIG. 3, the bubble rising speed is shown as a relative value when the bubble rising speed in the reference electrolyte having an electrolyte density increase rate of 0% is 1. From FIG. 3, it can be seen that the bubble rising speed increases as the electrolyte density increases.

Next, the rising speed of bubbles when the flow of the electrolytic solution 80 exists in the electrolytic cell 10, that is, the rising speed of bubbles under the flow of the electrolytic solution v _T considering both the buoyancy of the bubbles and the flow of the electrolytic solution 80. To consider. The rising speed v _T of the bubbles under the electrolyte flow is expressed by the following formula (3). It should be noted that the flow rate v _l of the electrolytic solution takes a positive value when the electrolytic solution flows in the upward direction of the bubbles.

  From the equation (3), it can be seen that when the flow direction of the electrolytic solution 80 coincides with the rising direction of the bubbles, the rising speed of the bubbles is increased.

  Therefore, from the formulas (1) to (3), when the density of the electrolytic solution 80 is increased to increase the rising speed of the bubbles, and the flow direction of the electrolytic solution 80 and the rising direction of the bubbles are matched, Even when electrolysis of water is performed using an electrolytic solution 80 having a high electrical conductivity without using the electrolytic cell 10 having a special shape for preventing oxygen, the oxygen gas 68, the hydrogen gas 78, etc. generated by the electrolysis of water It can be seen that the bubbles consisting of can be prevented from staying in the electrolytic cell 10.

(Function)
The operation of the alkaline water electrolysis apparatus 1 will be described. First, the electrolytic solution 80 in the electrolytic solution tank 50 is introduced into the anode chamber 20 of the electrolytic cell 10 using a liquid feed pump 64 provided in the anode chamber electrolytic solution supply system 61, and the cathode chamber electrolyte supply system 71. It is introduced into the cathode chamber 30 of the electrolytic cell 10 using a liquid feed pump 74 provided in the above.

  The flow rate of the electrolyte solution 80 introduced into the anode chamber 20 is measured by a flow meter 65 provided in the anode chamber electrolyte solution supply system 61, and a valve (not shown) provided in the anode chamber electrolyte solution supply system 61 is used. Adjusted. The flow rate of the electrolyte 80 introduced into the cathode chamber 30 is measured by a flow meter 75 provided in the cathode chamber electrolyte supply system 71, and a valve (not shown) provided in the cathode chamber electrolyte supply system 71 is used. Adjusted.

<Operation in the anode chamber>
Next, an operation when the electrolytic solution 80 is introduced into the anode chamber 20 of the electrolytic cell 10 will be described. When the electrolytic solution 80 is introduced into the anode chamber 20 of the electrolytic cell 10, the electrolytic solution 80 is upstream of the anode chamber of the anode chamber 20 through the bottom introduction part 26 provided at the bottom of the anode chamber 20 of the electrolytic cell 10. Introduced into portion 22. As shown in FIG. 2, the electrolytic solution 80 is introduced into the anode chamber upstream portion 22 from the bottom to the top of the bottom introduction portion 26.

  An anode chamber midstream portion 23 is provided vertically above the anode chamber upstream portion 22, an anode chamber downstream portion 24 is provided vertically above the anode chamber midstream portion 23, and a top discharge is vertically above the anode chamber downstream portion 24. A portion 28 is provided. For this reason, the electrolytic solution 80 introduced into the anode chamber 20 through the bottom introduction portion 26 flows upward in the anode chamber 20 and is electrolyzed in the middle to become the anode chamber solution 81, and then the top discharge portion. 28 is discharged from above.

  Further, a rectifying plate 27 for arbitrarily controlling the flow direction of the electrolytic solution 80 is disposed in the anode chamber upstream portion 22. For this reason, the flow of the electrolyte solution 80 in the anode chamber upstream portion 22 of the anode chamber 20 is rectified and the flow direction is controlled to an arbitrary direction. In the electrolytic cell 10 shown in FIG. 2, the rectifying plate 27 is controlled so that the flow direction of the electrolytic solution 80 in the upstream portion 22 of the anode chamber is directed from the lower side to the upper side in FIG. The electrolyte solution 80 rectified by the rectifying plate 27 in the anode chamber upstream portion 22 is sent to the anode chamber midstream portion 23 in a rectified state.

  In the anode chamber midstream portion 23, the electrolytic solution 80 is electrolyzed by the anode 25 provided in the anode chamber midstream portion 23 and the cathode 35 provided in the cathode chamber midstream portion 33 of the cathode chamber 30, and the anode chamber liquid 81. And oxygen gas 68 is produced.

  The anode chamber 20 and the cathode chamber 30 are partitioned by the diaphragm 40, and bubbles made of oxygen gas 68 and the like cannot pass through the diaphragm 40. Therefore, the oxygen gas 68 generated in the anode chamber 20 is The anode chamber 20 is moved up with the anode chamber liquid 81 and sent to the anode chamber downstream portion 24.

  The anode chamber downstream portion 24 is formed in a shape in which the anode chamber liquid 81 and the oxygen gas 68 smoothly flow upward, so that the flow of the electrolytic solution 80 in the anode chamber midstream portion 23 is not hindered. The anode chamber liquid 81 and the oxygen gas 68 in the anode chamber downstream portion 24 are smoothly discharged from the top discharge portion 28 of the anode chamber 20 to the anode chamber liquid circulation system 63 above the top discharge portion 28.

  The anode chamber liquid 81 and the oxygen gas 68 discharged from the anode chamber 20 of the electrolytic cell 10 to the anode chamber liquid circulation system 63 above the anode chamber 20 are the anode chamber liquid provided in the middle of the anode chamber liquid circulation system 63. The gas-liquid separator 66 separates the anode chamber liquid 81 and the oxygen gas 68.

  The oxygen gas 68 separated from the anode chamber liquid 81 by the anode chamber liquid-gas-liquid separator 66 flows through the oxygen gas system 67, and is sent to and stored in an oxygen gas storage system (not shown). Thus, according to the alkaline water electrolysis apparatus 1, the oxygen gas 68 can be produced by electrolysis in the anode chamber 20.

  On the other hand, the anode chamber liquid 81 separated from the oxygen gas 68 by the anode chamber liquid-gas-liquid separator 66 flows through the anode chamber liquid circulation system 63 and is sent to the electrolyte tank 50. Thus, in the alkaline water electrolysis apparatus 1, the electrolytic solution 80 sent from the electrolytic solution tank 50 to the anode chamber 20 of the electrolytic cell 10 is electrolyzed to become the anode chamber solution 81, and then returns to the electrolytic solution tank 50. A circulation cycle of the electrolytic solution 80 passing through the anode chamber 20 is formed.

  In the electrolyte tank 50, the anode chamber liquid 81 returned through the anode chamber liquid circulation system 63 and the cathode chamber liquid 82 returned through the cathode chamber liquid circulation system 73 are mixed and appropriately mixed. Then, an electrolyte solution 80 that can be introduced into the electrolytic cell 10 is prepared by supplying electrolyte.

  The liquid feed pump 64 supplies an electrolytic solution in an amount equal to or more than the consumption amount of the electrolytic solution 80 by electrolysis in the electrolytic cell 10 from the electrolytic solution tank 50 to the electrolytic cell 10, thereby causing the electrolytic solution 80 to pass through the anode chamber 20. The circulation cycle allows the electrolyte 80 at a constant flow rate to flow.

<Operation in the cathode chamber>
Next, an operation when the electrolytic solution 80 is introduced into the cathode chamber 30 of the electrolytic cell 10 will be described. The electrolyte solution 80 introduced into the cathode chamber 30 flows upward in the cathode chamber 30 and becomes the cathode chamber solution 82 in the same manner as the electrolyte solution 80 introduced into the anode chamber 20. It comes to be discharged from. The configuration in the cathode chamber 30 and the configuration in the anode chamber 20 are the same except for the difference between the cathode 35 and the anode 25. For this reason, the action when the electrolyte solution 80 is introduced into the cathode chamber 30 and the action when the electrolyte solution 80 is introduced into the anode chamber 20 are the same except for the action when the electrolyte solution 80 is electrolyzed. It is. However, in order to prevent misunderstanding due to omission of description, the operation when the electrolytic solution 80 is introduced into the cathode chamber 30 will be described in the same manner as the operation when the electrolytic solution 80 is introduced into the anode chamber 20.

  When the electrolytic solution 80 is introduced into the cathode chamber 30 of the electrolytic cell 10, the electrolytic solution 80 is upstream of the cathode chamber of the cathode chamber 30 through the bottom introduction part 36 provided at the bottom of the cathode chamber 30 of the electrolytic cell 10. Introduced into portion 32. As shown in FIG. 2, the electrolytic solution 80 is introduced into the cathode chamber upstream portion 32 from the bottom to the top of the bottom introduction portion 36.

  A cathode chamber midstream portion 33 is provided vertically above the cathode chamber upstream portion 32, a cathode chamber downstream portion 34 is provided vertically above the cathode chamber midstream portion 33, and a top discharge is vertically above the cathode chamber downstream portion 34. A portion 38 is provided. For this reason, the electrolytic solution 80 introduced into the cathode chamber 30 through the bottom introduction portion 36 flows upward in the cathode chamber 30 and is electrolyzed in the middle to become the cathode chamber solution 82, and then the top discharge portion. 38 is discharged from above.

  Further, a rectifying plate 37 for arbitrarily controlling the flow direction of the electrolytic solution 80 is disposed in the cathode chamber upstream portion 32. For this reason, the flow of the electrolytic solution 80 in the cathode chamber upstream portion 32 of the cathode chamber 30 is rectified and the flow direction is controlled in an arbitrary direction. In the electrolytic cell 10 shown in FIG. 2, the rectifying plate 37 is controlled such that the flow direction of the electrolytic solution 80 in the cathode chamber upstream portion 32 is directed from the lower side to the upper side in FIG. The electrolyte solution 80 rectified by the rectifying plate 37 in the cathode chamber upstream portion 32 is sent to the cathode chamber midstream portion 33 in a rectified state.

  In the cathode chamber midstream portion 33, the electrolytic solution 80 is electrolyzed by the cathode 35 provided in the cathode chamber midstream portion 33 and the anode 25 provided in the anode chamber midstream portion 23 of the anode chamber 20, and the cathode chamber liquid 82. And hydrogen gas 78 is produced.

  The cathode chamber 30 and the anode chamber 20 are partitioned by the diaphragm 40, and bubbles made of hydrogen gas 78 and the like cannot pass through the diaphragm 40. Therefore, the hydrogen gas 78 generated in the cathode chamber 30 is separated from the anode chamber 20 side. The cathode chamber liquid 82 rises together with the cathode chamber liquid 82 and is sent to the cathode chamber downstream portion 34.

  The cathode chamber downstream portion 34 is formed in a shape in which the cathode chamber solution 82 and the hydrogen gas 78 smoothly flow upward, so that the flow of the electrolyte solution 80 in the cathode chamber midstream portion 33 is not hindered. The cathode chamber liquid 82 and the hydrogen gas 78 in the cathode chamber downstream portion 34 are smoothly discharged from the top discharge portion 38 of the cathode chamber 30 to the cathode chamber liquid circulation system 73 above the top discharge portion 38.

  The cathode chamber liquid 82 and the hydrogen gas 78 discharged from the cathode chamber 30 of the electrolytic cell 10 to the cathode chamber liquid circulation system 73 above the cathode chamber 30 are the cathode chamber liquid provided in the middle of the cathode chamber liquid circulation system 73. The cathode chamber liquid 82 and the hydrogen gas 78 are separated by the gas-liquid separator 76.

  The hydrogen gas 78 separated from the cathode chamber liquid 82 by the cathode chamber liquid-gas-liquid separator 76 flows through the hydrogen gas system 77 and is sent to and stored in a hydrogen gas storage system (not shown). Thus, according to the alkaline water electrolysis apparatus 1, the hydrogen gas 78 can be produced by electrolysis in the cathode chamber 30.

  On the other hand, the cathode chamber liquid 82 separated from the hydrogen gas 78 by the cathode chamber liquid-gas-liquid separator 76 flows through the cathode chamber liquid circulation system 73 and is sent to the electrolyte tank 50. Thus, in the alkaline water electrolysis apparatus 1, the electrolytic solution 80 sent from the electrolytic solution tank 50 to the cathode chamber 30 of the electrolytic cell 10 is electrolyzed to become the cathode chamber solution 82, and then returns to the electrolytic solution tank 50. A circulation cycle of the electrolytic solution 80 passing through the cathode chamber 30 is formed.

  In the electrolytic solution tank 50, the cathode chamber liquid 82 returned through the cathode chamber liquid circulation system 73 and the anode chamber liquid 81 returned through the anode chamber liquid circulation system 63 are mixed and appropriately mixed. Then, an electrolyte solution 80 that can be introduced into the electrolytic cell 10 is prepared by supplying electrolyte.

  The liquid feed pump 74 supplies an electrolytic solution in an amount equal to or greater than the consumption amount of the electrolytic solution 80 by the electrolysis in the electrolytic cell 10 from the electrolytic solution tank 50 to the electrolytic cell 10, whereby the electrolytic solution 80 passing through the cathode chamber 30. The circulation cycle allows the electrolyte 80 at a constant flow rate to flow.

(effect)
According to the alkaline water electrolysis apparatus 1, bubbles can be prevented from staying in the electrolytic cell 10 and the electrolysis efficiency of water electrolysis can be increased.

  According to the alkaline water electrolysis apparatus 1, the retention of bubbles in the electrolytic cell 10 can be prevented and the efficiency of water electrolysis can be increased, so that the current input for water electrolysis uses renewable energy. Even when it fluctuates due to power generation or the like, it is possible to efficiently operate water electrolysis.

  FIG. 1 shows an example in which one electrolytic cell 10 is provided as the alkaline water electrolysis apparatus 1. However, the alkaline water electrolysis apparatus of the present invention may include a plurality of electrolytic cells 10. When the alkaline water electrolysis apparatus includes a plurality of electrolytic cells 10, the plurality of electrolytic cells 10 can be arranged in series, parallel, or a combination of series and parallel.

  Here, the series arrangement of the plurality of electrolytic cells 10 means that the anode chamber liquid 81 discharged from the anode chamber 20 of the nth electrolytic cell 10 is introduced into the anode chamber 20 of the (n + 1) th electrolytic cell 10. The cathode chamber liquid 82 discharged from the cathode chamber 30 of the nth electrolytic cell 10 is introduced into the cathode chamber 30 of the (n + 1) th electrolytic cell 10.

  In addition, the parallel arrangement of the plurality of electrolytic cells 10 means that the electrolyte solution 80 is introduced and the anode chamber solution 81 is discharged for each of the anode chambers 20 of the plurality of electrolytic cells 10. For each of the ten cathode chambers 30, it means an arrangement in which the electrolyte solution 80 is introduced and the cathode chamber solution 82 is discharged.

  In the alkaline water electrolysis apparatus of the present invention, by setting a plurality of electrolytic cells 10 and arranging the electrolytic cells 10 in series, parallel, or a combination of series and parallel, current or voltage for electrolysis can be set. This is preferable because the degree of freedom is high.

  In the alkaline water electrolysis apparatus of the present invention, the power, current, and voltage supplied between the anode 25 and the cathode 35 of the electrolytic cell 10 can be appropriately set.

  Examples are shown below, but the present invention is not construed as being limited thereto.

[Example 1]
(Measurement of K ⁺ concentration of electrolyte and electrical conductivity)
Pure water Kanto Chemical Co., Ltd. 48% potassium hydroxide aqueous solution (deer grade) was dissolved to prepare four types of electrolytes having a K ⁺ molar weight concentration of 3.0 to 8.6 mol / kg. The molar weight concentration of K ⁺ is the same numerical value as the molar weight concentration with KOH.
Electrical conductivity was measured for four types of electrolytes. The measurement results are shown in FIG.
FIG. 4 shows that the electrical conductivity of the electrolytic solution is high when K ⁺ is in the range of about 3 to 8 mol / kg, particularly about 4 to 7 mol / kg.

[Example 2]
(Measurement of the relationship between the electrical conductivity and the K ⁺ and Cs ⁺ concentration ratio in the electrolyte)
In pure water, a 48% potassium hydroxide aqueous solution (deer grade) manufactured by Kanto Chemical Co., Ltd. and a 50% cesium hydroxide (CsOH) aqueous solution manufactured by Alfa Aeaser are dissolved, and the molar weight of the total molar amount of K ⁺ and Cs ⁺ Three types of electrolytes having a concentration of 6 mol / kg and a K ⁺ and Cs ⁺ concentration ratio {K ⁺ / (K ⁺ + Cs ⁺ )} of 0.80 to 0.91 were prepared.
Electrical conductivity was measured for three types of electrolytes. The measurement results are shown in FIG.
From FIG. 5, when the molar weight concentration of the total molar amount of K ⁺ and Cs ⁺ is 6 mol / kg, the electrical conductivity of the electrolyte solution is within a range where K ⁺ / (K ⁺ + Cs ⁺ ) exceeds 0.85. It turns out that it becomes high.

[Example 3]
(Measurement of relationship between KOH concentration of electrolyte and electrolyte density)
A 48% potassium hydroxide aqueous solution (deer grade) manufactured by Kanto Chemical Co., Ltd. was dissolved in pure water to prepare five types of electrolytes having a KOH molar weight concentration of 0 to 7 mol / kg.
The density was measured for five types of electrolytes. The measurement results are shown in FIG.
FIG. 6 shows that the density of the electrolytic solution increases as the KOH concentration increases.

[Example 4]
(Measurement of the relationship between the concentration ratio of K ⁺ and Cs ^{+ in} the electrolyte and the density of the electrolyte)
In pure water, a 48% potassium hydroxide aqueous solution (deer grade) manufactured by Kanto Chemical Co., Ltd. and a 50% cesium hydroxide (CsOH) aqueous solution manufactured by Alfa Aeaser are dissolved, and the molar weight of the total molar amount of K ⁺ and Cs ⁺ Three types of electrolytes having a concentration of 6 mol / kg and a K ⁺ and Cs ⁺ concentration ratio {K ⁺ / (K ⁺ + Cs ⁺ )} of 0.80 to 0.91 were prepared.
The density was measured for three types of electrolytes. The measurement results are shown in FIG.
FIG. 7 shows that when the molar weight concentration of the total molar amount of K ⁺ and Cs ⁺ is 6 mol / kg, the density of the electrolytic solution increases as K ⁺ / (K ⁺ + Cs ⁺ ) decreases.

[Example 5]
(Measurement of the relationship between the electrical conductivity and the K ⁺ and Cs ⁺ concentration ratio in the electrolyte)
In pure water, a 48% potassium hydroxide aqueous solution (deer grade) manufactured by Kanto Chemical Co., Ltd. and a 50% cesium hydroxide (CsOH) aqueous solution manufactured by Alfa Aeaser are dissolved, and the molar weight of the total molar amount of K ⁺ and Cs ⁺ Three types of electrolytes having a concentration of 6 mol / kg and a ratio K ⁺ / (K ⁺ + Cs ⁺ ) of K ⁺ and Cs ⁺ of 0.8 to 1 were prepared.
Electrical conductivity was measured for three types of electrolytes. The measurement results are shown in FIG. In addition, the electrical conductivity of FIG. 8 is shown as a relative value when the electrical conductivity in the reference electrolytic solution in which K ⁺ / (K ⁺ + Cs ⁺ ) is 1 is 1.
From FIG. 8, when the molar weight concentration of the total molar amount of K ⁺ and Cs ⁺ is 6 mol / kg, the K ⁺ / (K ⁺ + Cs ⁺ ) approaches 1 to 0.8, that is, the electrolyte is KOH. In addition, it can be seen that when KOH and CsOH are contained, the electrical conductivity of the electrolytic solution increases.

From the results of Examples 1 to 5, it was found that the electrolytic efficiency was improved when the electrolytic solution contained KOH and CsOH as compared with the case where the electrolytic solution contained only KOH as the electrolyte.
Even when the electrolyte contains KOH and CsOH, the effect of improving the electrolytic efficiency varies depending on the mixing ratio of KOH and CsOH. When K ⁺ / (K ⁺ + Cs ⁺ ) is 0.8, the electrolytic efficiency is improved. It turned out that the effect of is the highest.

[Example 6]
(Measurement of the relationship between electrolyte flow rate and electrolytic efficiency)
A 48% potassium hydroxide aqueous solution (deer grade) manufactured by Kanto Chemical Co., Ltd. was dissolved in pure water to prepare an electrolytic solution having a KOH molar weight concentration of 6 mol / kg.
This electrolytic solution is introduced into the electrolytic cell 10 of the alkaline water electrolysis apparatus 1 shown in FIG. 1, and the total flow rate of the electrolytic solution introduced into the anode chamber 20 and the cathode chamber 30 of the electrolytic cell 10 is 0 ml / min, 210 ml / The electric conductivity of the electrolyte solution was measured when it was min and 830 ml / min. The flow rates of the electrolytic solution introduced into each of the anode chamber 20 and the cathode chamber 30 are 0 ml / min, 105 ml / min, and 415 ml / min, which are half the above flow rates.
Here, the flow rate (ml / min) of the electrolytic solution is not a value measured by the flow meters 65 and 75, but the total replacement amount in the case where the electrolytic solution in the electrolytic cell 10 is appropriately and intermittently replaced by time. It is calculated by dividing. Specifically, the flow rate (ml / min) of the electrolytic solution is set in advance in a suitable range of a composition suitable for electrolysis of the electrolytic solution, so that the composition of the electrolytic solution does not deviate from this preferred range. The total replacement amount of the electrolytic solution when the electrolytic solution in the electrolytic cell 10 was intermittently replaced was calculated by dividing by time.
The measurement results are shown in FIG. In FIG. 9, electrolytic efficiency is used as the vertical axis. This electrolysis efficiency is obtained by dividing the electric conductivity values when the electrolyte flow rate is 0 ml / min, 210 ml / min, and 830 ml / min by the electric conductivity value when the electrolyte flow rate is 0 ml / min. It is a thing. For this reason, the value of electrolysis efficiency is 1 when the electrolyte flow rate is 0 ml / min.
FIG. 9 shows that the electrolytic efficiency of the electrolytic solution increases as the flow rate of the electrolytic solution increases. Moreover, when the same experiment was conducted by changing the power supplied to the anode 25 and the cathode 35, it was found that the electrolytic efficiency increased as the electrolyte flow rate increased, regardless of the amount of power supplied.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Alkaline water electrolysis apparatus 10 Electrolytic cell 20 Anode chamber 21 Anode chamber main body 22 Anode chamber upstream portion 23 Anode chamber midstream portion 24 Anode chamber downstream portion 25 Anode 26 Bottom introduction portion 27 Rectifier plate 28 Top discharge portion 30 Cathode chamber 31 Cathode chamber body 32 Cathode chamber upstream portion 33 Cathode chamber midstream portion 34 Cathode chamber downstream portion 35 Cathode 36 Bottom introduction portion 37 Rectifier plate 38 Top discharge portion 40 Diaphragm 50 Electrolyte tank 61 Anode chamber electrolyte supply system 62 Anode chamber liquid discharge system 63 Anode chamber Liquid circulation system 64 Liquid feed pump 65 Flow meter 66 Anode chamber liquid-gas-liquid separator 67 Oxygen gas system 68 Oxygen gas (oxygen)
71 Cathode Chamber Electrolyte Supply System 72 Cathode Chamber Liquid Discharge System 73 Cathode Chamber Liquid Circulation System 74 Feed Pump 75 Flow Meter 76 Cathode Chamber Liquid Gas-Liquid Separator 77 Hydrogen Gas System 78 Hydrogen Gas (Hydrogen)
80 Electrolytic solution 81 Anode chamber solution 82 Cathode chamber solution

Claims (13)

An anode chamber in which an anode is disposed, a cathode chamber in which a cathode is disposed, and a diaphragm partitioning the anode chamber and the cathode chamber, and hydrogen is produced by electrolyzing an electrolytic solution made of a basic aqueous solution. An alkaline water electrolysis apparatus equipped with an electrolytic cell,
The electrolytic cell is electrolyzed by the anode and the cathode while the electrolytic solution introduced from the bottom introduction portion of the anode chamber flows upward in the anode chamber toward the top discharge portion of the anode chamber. The anode chamber liquid and oxygen gas are generated, the anode chamber liquid and oxygen gas are discharged from the top discharge portion of the anode chamber, and the electrolyte introduced from the bottom introduction portion of the cathode chamber is the cathode. In the middle of flowing upward in the cathode chamber toward the top discharge portion of the chamber, the cathode and the cathode are electrolyzed to generate a cathode chamber liquid and hydrogen gas, and the cathode chamber liquid is generated from the top discharge portion of the cathode chamber. And hydrogen gas is discharged,
The electrolyte solution is alkaline water characterized in that the pH measured at 27 ° C. is 14 or more, the electrical conductivity measured at 27 ° C. is 0.25 S / cm or more, and the density is 1.25 kg / m ³ or more. Electrolytic device. The anode chamber of the electrolytic cell includes an anode chamber midstream portion provided with the anode, an anode chamber upstream portion located on the bottom portion introduction side of the anode chamber from the anode chamber midstream portion, and an anode chamber midstream portion. An anode chamber downstream portion located on the top discharge portion side of the anode chamber,
The cathode chamber of the electrolytic cell includes a cathode chamber midstream portion provided with the cathode, a cathode chamber upstream portion located on the bottom portion introduction side of the cathode chamber from the cathode chamber midstream portion, and a cathode chamber midstream portion. A cathode chamber downstream portion located on the top discharge portion side of the cathode chamber,
In the anode chamber upstream portion of the anode chamber and the cathode chamber upstream portion of the cathode chamber, a rectifying plate for arbitrarily controlling the flow direction of the electrolyte solution is disposed,
The anode chamber downstream portion of the anode chamber is formed in a shape in which the anode chamber liquid and oxygen gas flow upward,
2. The alkaline water electrolysis apparatus according to claim 1, wherein the cathode chamber downstream portion of the cathode chamber is formed in a shape in which the cathode chamber liquid and hydrogen gas flow upward. An anode chamber liquid-gas-liquid separator that separates the anode chamber liquid and oxygen gas discharged from the anode chamber of the electrolytic cell;
The alkaline water electrolysis apparatus according to claim 1 or 2, further comprising a cathode chamber liquid-gas-liquid separator that separates the cathode chamber liquid and hydrogen gas discharged from the cathode chamber of the electrolytic cell. An electrolytic solution tank for storing an electrolytic solution to be supplied to the electrolytic cell;
A liquid feed pump for transferring the electrolytic solution in the electrolytic solution tank to the anode chamber and the cathode chamber of the electrolytic cell;
An anode chamber liquid circulation system for transferring the anode chamber liquid discharged from the anode chamber of the electrolytic cell to the electrolyte tank;
A cathode chamber liquid circulation system for transferring the cathode chamber liquid discharged from the cathode chamber of the electrolytic cell to the electrolyte tank;
The anode chamber liquid-liquid separator is provided in the middle of the anode chamber liquid circulation system,
4. The alkaline water electrolysis apparatus according to claim 3, wherein the cathode chamber liquid-liquid separator is provided in the middle of the cathode chamber liquid circulation system. The alkaline water electrolysis apparatus according to any one of claims 1 to 4, wherein the density of the electrolytic solution is controlled by adjusting a kind or concentration of a cation in the electrolytic solution. The alkaline water electrolysis apparatus according to claim 1, wherein the electrolytic solution contains KOH. 6. The alkaline water electrolysis apparatus according to claim 1, wherein the electrolytic solution contains KOH and an alkali metal hydroxide other than KOH. The alkaline water electrolysis apparatus according to claim 7, wherein the alkali metal hydroxide other than KOH is at least one selected from RbOH and CsOH. The alkaline water electrolysis apparatus according to any one of claims 6 to 8, wherein the electrolytic solution has a KOH concentration of 4 to 7 mol / kg. 10. The electrolyte solution according to claim 6, wherein a ratio of the content of KOH to the content of alkali metal hydroxide is in a range of 80 to 100 mass%. Alkaline water electrolyzer. The alkaline water electrolysis apparatus according to any one of claims 6 to 10, wherein the electrolytic solution has a concentration of the alkali metal of 3 to 8 mol / kg. The said liquid feeding pump can supply the amount of electrolytes more than the consumption of the said electrolyte solution by the said electrolysis from the said electrolyte solution tank to the said electrolytic vessel, The any one of Claims 6-11 characterized by the above-mentioned. The alkaline water electrolysis apparatus according to item. An anode chamber in which an anode is disposed, a cathode chamber in which a cathode is disposed, and a diaphragm partitioning the anode chamber and the cathode chamber, and hydrogen is produced by electrolyzing an electrolytic solution made of a basic aqueous solution. An alkaline water electrolysis method using an alkaline water electrolysis apparatus comprising an electrolytic cell,
The electrolytic cell is electrolyzed by the anode and the cathode while the electrolytic solution introduced from the bottom introduction portion of the anode chamber flows upward in the anode chamber toward the top discharge portion of the anode chamber. The anode chamber liquid and oxygen gas are generated, the anode chamber liquid and oxygen gas are discharged from the top discharge portion of the anode chamber, and the electrolyte introduced from the bottom introduction portion of the cathode chamber is, In the middle of flowing upward in the cathode chamber toward the top discharge portion of the cathode chamber, the anode and the cathode are electrolyzed to generate a cathode chamber liquid and hydrogen gas, and from the top discharge portion of the cathode chamber, the Cathode chamber liquid and hydrogen gas are discharged,
Alkaline water characterized in that the electrolytic solution has a pH measured at 27 ° C. of 14 or more, an electrical conductivity measured at 27 ° C. of 0.25 S / cm or more, and a density of 1.25 kg / m ³ or more. Electrolysis method.