JP2021195596A - Alkaline water electrolysis tank - Google Patents

Abstract

To provide a multi-pole water electrolysis tank with long life.SOLUTION: A multi-pole water electrolysis tank comprises: a plurality of multi-pole elements 60, each of which includes an anode 2a, a cathode 2c, a partition for separating the anode from the cathode, and an outer frame for bordering the partition; a cell stack (a) including a stack of microporous diaphragms placed between the adjacent elements with gaskets; and a hydraulic control mechanism (g) for applying a surface pressure to gaps between the gaskets and the diaphragms, and between the gaskets and the elements. An alkaline water electrolysis tank may be configured as the multi-pole water electrolysis tank, also comprising: a primary gasket (b), which is disposed between at least a pair of the elements, for sealing an electrolyte and generated gas; and a secondary gasket (c), which is disposed on the outer side of the primary gasket (b), for preventing the electrolyte that leaks out of the sealing range of the primary gasket (b) from leaking out of the electrolysis tank.SELECTED DRAWING: Figure 1

Description

The present invention relates to an alkaline water electrolytic cell.

In recent years, in order to solve problems such as global warming caused by greenhouse gases such as carbon dioxide and reduction of fossil fuel reserves, technologies such as wind power generation and solar power generation using renewable energy have been attracting attention.

Renewable energy has the property that its output is very variable because its output depends on climatic conditions. Therefore, it is not always possible to transport the electric power obtained from power generation by renewable energy to the general electric power system, and there are concerns about social impacts such as imbalance between supply and demand of electric power and destabilization of the electric power system. There is.

Therefore, research is being conducted to replace the electric power generated from renewable energy with a form that can be stored and transported. Specifically, it has been considered to generate hydrogen that can be stored and transported by electrolysis (electrolysis) of water using electricity generated from renewable energy, and to use hydrogen as an energy source or a raw material. There is.

Hydrogen is widely used industrially in the fields of petroleum refining, chemical synthesis, metal refining, etc., and in recent years, it can be used in hydrogen stations for fuel cell vehicles (FCVs), smart communities, hydrogen power plants, etc. The sex is also spreading. Therefore, there are high expectations for the development of technology for obtaining hydrogen from renewable energy.

As a method of electrolysis of water, there are solid polymer type water electrolysis method, high temperature steam electrolysis method, alkaline water electrolysis method, etc., but they have been industrialized for more than several decades and can be carried out on a large scale. Alkaline water electrolysis is considered to be one of the most promising ones because it is cheaper than other water electrolyzers.

However, in order to adapt water electrolysis as a means for storing and transporting energy in the future, as described above, it will be possible to efficiently and stably utilize power with large fluctuations in output to perform water electrolysis. It is necessary to solve various problems of electrolysis cells and devices for water electrolysis.

International Publication No. 14/178317

In an electrolytic cell in which a plurality of electrolytic cells are connected (stacked) in series, the gasket that seals between the electrode elements constituting the electrolytic cell is compressed, so that the surface pressure (seal) between the gasket and each element is compressed. Surface pressure) is obtained and the outflow of the electrolytic solution is prevented.
In the conventional hydraulically controlled electrolytic cell, a rubber gasket has been used as a gasket for sealing the electrolytic solution and the generated gas, but the realization of a high-pressure water electrolysis system using renewable energy has the following problems. be.
(1) When electrolyzing renewable energy as a power source, the electrolytic output is not constant because it is affected by the weather and the like. Since the pressure inside the electrolytic cell also fluctuates as the output fluctuates, the fluctuation frequency and fluctuation range of the stack pressure increase, and the frequency of operation stoppage also increases.
(2) A rubber gasket has been used in the conventional hydraulic control type electrolytic cell, but since the gasket surface pressure fluctuates greatly due to the fluctuation of the stack pressure, the stack pressure is increased according to the increase in the internal pressure by the hydraulic control. I needed it.
(3) When the internal pressure during operation is increased for high efficiency, the difference between the stack pressure during stop and operation becomes large, and the stack pressure control becomes more severe. (4) The internal pressure during operation is high. Indeed, the rubber gasket tends to protrude out of the electrolytic cell. In order to prevent protrusion, it is necessary to increase the stack pressure, but excessive stack pressure promotes creep and damages the gasket, which leads to a decrease in the life of the electrolytic cell.
(5) In the case of a large high-pressure electrolytic cell, the area for receiving the generated internal pressure is widened, so that a higher stack pressure is required, which leads to a decrease in the life of the electrolytic cell.
(6) It is possible to increase the stack pressure by using a gasket made of high-strength resin or the like, but the resin gasket is inferior in sealing performance to the rubber gasket (7) Hydraulically controlled electrolytic cell. Stacks a plurality of electrolytic cells in the horizontal direction, but it is difficult to replace the diaphragms and gaskets constituting each cell on the spot when the stack is opened.
(8) In order to replace the members, it is necessary to release the electrolytic cells from the stacked state and then set the electrolytic cells on the workbench one frame at a time to perform the replacement work. In particular, since the large frame is heavy, workability is poor due to crane work, and the electrolysis tank stop time during work is prolonged, leading to a decrease in electrolysis efficiency.
(9) When the diaphragm is fixed only by compressing the gasket in the above-mentioned member replacement, the diaphragm falls due to its own weight when the stack is opened, so that it is more difficult to replace and assemble the member with the electrolytic cell upright. be.
(10) In order to seal the electrolytic solution and the generated gas, it is necessary to bring the diaphragm into contact with the gasket to prevent leakage. However, when a porous diaphragm is used, the electrolytic solution permeates the inside of the diaphragm, so that the liquid is external. Leaks into.

As described above, in the hydraulically controlled electrolytic cell, the stack pressure fluctuation frequency increases and the maximum stack pressure increases due to the increase in the fluctuation range of the electrolytic cell internal pressure and the increase in the internal pressure. An increase in stack pressure increases gasket protrusion and compressive strain, causing leakage of electrolyte and generated gas, and breakage or breakage of the gasket. Improving the pressure resistance of the electrolytic cell and the robustness to fluctuations in the internal pressure leads to a longer life of the water electrolytic cell and the water electrolytic cell device and a reduction in maintenance frequency.

Therefore, in view of the above-mentioned problems, the present invention provides a multi-pole electrolytic cell for water electrolysis, which has a high frequency of variable power supply and operation stoppage and has a long life even when the internal pressure of the electrolytic cell is high. The purpose.

That is, the present invention is as follows.
[1]
An anode terminal element with an anode and
A cathode terminal element with a cathode and
A plurality of duplexers located between the anode terminal element and the cathode terminal element, comprising an anode, a cathode, a partition wall separating the anode and the cathode, and an outer frame (d) edging the partition wall. Polar element and
With the cell stack (a) in which the microporous diaphragm disposed between the adjacent elements is stacked via a gasket;
With a hydraulic control mechanism (g) that applies surface pressure between the gasket and the diaphragm, and between the gasket and each of the elements;
It is a multi-pole electrolytic cell for water electrolysis equipped with
Located outside the primary gasket (b) that seals the electrolytic solution and the generated gas between at least one pair of the elements, and outside the sealing range of the primary gasket (b). An alkaline water electrolytic cell, characterized in that it is provided with a secondary gasket (c) for preventing leakage of the electrolytic cell that has flowed out to the outside of the electrolytic cell.
[2]
The alkaline water electrolytic cell according to [1], wherein the primary gasket (b) is a rubber gasket and the secondary gasket (c) is a high-strength gasket.
[3]
The alkaline water electrolytic cell according to [1] or [2], wherein the primary gasket (b) has a tensile stress σ at the time of 100% deformation of 30 MPa or less.
[4]
The alkaline water electrolytic cell according to any one of [1] to [3], wherein the secondary gasket (c) has a Young's modulus E of 200 MPa or more.
[5]
Of [1] to [4], the ratio E / σ of the Young's modulus E of the secondary gasket (c) to the tensile stress σ at the time of 100% deformation of the primary gasket (b) is E / σ ≧ 10. The multi-pole electrolytic cell for water electrolysis described in any one.
[6]
The outer frame (d) of the multipolar element is provided with a groove structure (e) for installing the primary gasket (b), and the depth of the groove structure (e) is such that the primary gasket is installed. 4. The method according to any one of [1] to [5], wherein the height is smaller than the height of (b), and at least the side wall (f) is provided on the outer peripheral surface side of the primary gasket (b). Alkaline water electrolytic cell.
[7]
The alkaline water electrolysis according to [6], wherein the groove structure (e) has a shape in which the side wall (f) and at least a part of the outer peripheral surface of the primary gasket (b) are in contact with each other. Tank.
[8]
The alkaline water electrolytic cell according to [6] or [7], wherein the groove structure (e) further has a side wall on the inner peripheral surface side of the primary gasket (b).
[9]
The alkaline water electrolytic cell according to any one of [1] to [8], wherein the secondary gasket (c) has an insulating property.
[10]
The alkaline water electrolytic cell according to [9], wherein the secondary gasket (c) has a volume resistance of 1 MΩ · cm or more at an electrolytic temperature.
[11]
The secondary gasket (c) supports compression in the stacking direction and is characterized in that the distance between the outer frames (d) of adjacent elements during stacking is kept within the range of 0.5 mm to 5 mm. 1] The alkaline water electrolytic cell according to any one of [10].
[12]
The alkaline water electrolytic cell according to any one of [1] to [11], wherein the stack pressure is controlled by hydraulic control of the plurality of the bipolar electrolytic cells.
[13]
The alkaline water electrolytic cell according to any one of [1] to [12], wherein the bipolar element has a fall prevention mechanism (f) for the diaphragm in the outer frame (d).
[14]
The alkaline water electrolytic cell according to [13], wherein the fall prevention mechanism (f) is installed between the primary gasket (b) and the secondary gasket (c).

According to the present invention, it is possible to provide a multi-pole electrolytic cell for water electrolysis, which has a high frequency of variable power supply and operation stoppage and has a long life even when the internal pressure of the electrolytic cell is high. In addition, the work time during maintenance is shortened, and the operating rate of the device is improved.

It is a side view which shows the whole of the example of the multi-pole type electrolytic cell for water electrolysis of this embodiment. It is a figure which shows an example of the cross section of the gasket, the groove structure, and the zero gap structure part in the electrolytic cell of the part of the broken line square frame of FIG. It is a figure which shows another example of the gasket and the groove structure in the electrolytic cell of the part of the broken line square frame of FIG. 1, and the cross section of a zero gap structure part. It is a figure which shows the outline of the electrolysis apparatus for water electrolysis of this embodiment.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

The alkaline water electrolytic cell of the present embodiment may be configured as a multi-pole electrolytic cell for water electrolysis.

<Multi-pole electrolytic cell for water electrolysis>
The multi-pole electrolytic cell for water electrolysis of the present embodiment is an electrolytic cell provided with a hydraulic control mechanism (g) that applies a stack pressure to the cell stack (a) and can change the stack pressure according to fluctuations in the internal pressure of the electrolytic cell. There is, between at least one pair of elements, located outside the primary gasket (b) that seals the electrolyte and the generated gas, and outside the sealing range of the primary gasket (b). It is characterized by comprising a secondary gasket (c) for preventing the outflow of the electrolytic solution from leaking to the outside of the electrolytic cell.
Here, the outside of the primary gasket (b) may be the outside of the outer edge of the primary gasket (b). Further, the outside of the sealing range of the primary gasket (b) may be outside the range surrounded by the outer circumference of the primary gasket (b).
In this embodiment, the details will be described later, but it is preferable that the primary gasket (b) is a rubber gasket and the secondary gasket (c) is a high-strength gasket.

The cell stack (a) is located between the anode terminal element having an anode, the cathode terminal element having a cathode, and the anode terminal element and the cathode terminal element, and separates the anode, the cathode, and the anode and the cathode. A plurality of bipolar elements having a partition wall and an outer frame (d) edging the partition wall, and a diaphragm arranged between the adjacent elements are stacked (laminated) via a gasket. In the present disclosure, the stacking direction of the cell stack (a) is also simply referred to as a "stacking direction".

The hydraulic control mechanism (g) fastens the cell stack by hydraulic pressure from both sides of the cell stack (a), and applies surface pressure (seal surface pressure) between the gasket and the diaphragm and between the gasket and each element. The tightening hydraulic pressure is controlled so that an appropriate stack pressure can be obtained according to the increase or decrease in the internal pressure of the electrolytic cell.

Hereinafter, the configuration of an example of the multipolar electrolytic cell for water electrolysis of the present embodiment will be described with reference to the drawings.

FIG. 1 shows a side view of an entire example of a bipolar electrolytic cell for water electrolysis according to the present embodiment.
FIG. 2A shows an example of a cross section of the gasket, the groove structure, and the zero gap structure portion inside the electrolytic cell in the portion of the broken line square frame in FIG.
FIG. 2B shows another example of the gasket and groove structure inside the electrolytic cell in the portion of the broken line square frame in FIG. 1 and the cross section of the zero gap structure portion.

The outer frame (d) constituting the multi-pole element has a groove structure (e) for installing the primary gasket (b), and the primary gasket (b) to be installed with the side wall on the atmospheric side (outer peripheral surface side) thereof. It is installed in a state where the outer peripheral surfaces of the are in contact with each other. The secondary gasket (c) is installed outside the primary gasket (b) of the outer frame (d).
The groove structure (e) is not limited to the primary gasket (b) position, but can be installed at the secondary gasket (c) position.

The groove structure (e) may have a side wall (f) in a direction orthogonal to the stack direction, and may have a side wall located outside the element and a side wall located inside the element. The side wall located on the outside of the element is on the outer peripheral surface side of the primary gasket (b), and the side wall located on the inside of the element is on the inner peripheral surface side of the primary gasket (b).

In the example shown in FIGS. 1 and 2, the water electrolysis bipolar electrolytic cell 50 of the present embodiment has an anode terminal element 51, an anode side primary gasket (b), a diaphragm 4, and a cathode side primary gasket (from one end to each other. b) The multi-pole elements 60 are arranged side by side in this order. At this time, the multi-pole element 60 is arranged so that the cathode 2c faces the anode terminal element 51a side. From the primary gasket (b) on the anode side to the multipolar element 60, as many as necessary for the design production amount are repeatedly arranged. After repeatedly arranging the anode side primary gasket (b) to the multipolar element 60 as many times as necessary, the anode side primary gasket (b), the diaphragm 4, and the cathode side primary gasket (b) are arranged side by side again. Finally, the cathode terminal elements 51c are arranged in this order. The multi-pole electrolytic cell 50 for water electrolysis is embodied by tightening the whole with a hydraulic control mechanism (g) to become a multi-pole electrolytic cell 50. The area from the anode terminal element 51a to the cathode terminal element 51c is referred to as a cell stack (a).
The arrangement constituting the bipolar electrolytic cell 50 for water electrolysis can be arbitrarily selected from the anode 2a side or the cathode 2c side, and is not limited to the above-mentioned order.
Further, in the bipolar electrolytic cell 50 for water electrolysis of the present embodiment, as shown in FIG. 2, a zero gap structure Z in which the diaphragm 4 is in contact with the anode 2a and the cathode 2c is formed, although not particularly limited. Is preferable.

The multi-pole type is one of the methods for connecting a large number of cells to a power source. A plurality of multi-pole elements 60 having an anode 2a on one side and a cathode 2c on one side are arranged in the same direction and connected in series, and only at both ends. Is a way to connect to the power supply.
The multi-pole electrolytic cell 50 for water electrolysis has a feature that the current of a power source can be reduced, and a compound, a predetermined substance, or the like can be mass-produced in a large amount in a short time by electrolysis. As for the power supply equipment, if the output is the same, the constant current and high voltage are cheaper and more compact, so industrially, the multi-pole type is preferable to the single-pole type.

In the present embodiment, in particular, in the bipolar electrolytic cell 50, a portion between two adjacent bipolar elements 60 between the partition walls 1 and between the adjacent bipolar element 60 and the terminal element. The portion between the partition walls 1 of each other is referred to as an electrolytic cell 65. The electrolytic cell 65 includes a partition wall 1 of one element, an anode chamber 5a, an anode 2a, and a diaphragm 4, and a cathode 2c, a cathode chamber 5c, and a partition wall 1 of the other element.

<< Cell stack (a) >>
As shown in FIG. 1, the cell stack (a) included in the water electrolysis multi-pole electrolytic cell 50 of the present embodiment has a multi-pole element 60 between the anode terminal element 51a and the cathode terminal element 51c. It consists of stacking the required number of stacks.
In the cell stack (a), the diaphragm 4 is formed between the anode terminal element 51a and the multipolar element 60, between the bipolar elements 60 arranged adjacent to each other, and between the multipolar element 60 and the cathode terminal element 51c. It is placed between.
As shown in FIG. 1, adjacent elements 51a, 60, 51c, and each element 51a, 60, 51c and the diaphragm 4 are stacked via a primary gasket (b).

As shown in FIGS. 1 and 2, the multi-pole element 60 includes a partition wall 1 that separates the anode 2a and the cathode 2c, and includes an outer frame (d) that borders the partition wall 1. More specifically, the partition wall 1 has conductivity, and the outer frame (d) is provided so as to surround the partition wall 1 along the outer edge of the partition wall 1.
In the present embodiment, the multipolar element 60 may be used so that the given direction D1 along the partition wall 1 is usually in the vertical direction, and specifically, the partition wall is as shown in FIG. When the plan view shape of 1 is rectangular, it may be used so that the given direction D1 along the partition wall 1 is in the same direction as the direction of one of the two facing sides. In the present specification, the vertical direction is also referred to as an electrolytic solution passing direction.

In the bipolar electrolytic cell 50 for water electrolysis in the present embodiment, as shown in FIG. 2, the partition wall 1, the outer frame (d), and the diaphragm 4 define an electrode chamber 5 through which the electrolytic solution passes.
In the present embodiment, in particular, in the bipolar electrolytic cell 50 for water electrolysis, the portion between the partition walls 1 between the two adjacent bipolar elements 60, and the adjacent bipolar element 60 and the terminal element. The portion between the two partition walls 1 is referred to as an electrolytic cell 65. The electrolytic cell 65 includes a partition wall 1 of one element, an anode chamber 5a, an anode 2a, and a diaphragm 4, and a cathode 2c, a cathode chamber 5c, and a partition wall 1 of the other element.
In the examples shown in FIGS. 1 and 2, the partition wall 1, the anode 2a, and the cathode 2c all have a plate-like shape having a predetermined thickness, but the present invention is not limited to this, and the entire cross section is not limited to this. Alternatively, the shape may be partially zigzag or wavy, or may have a rounded end.

Specifically, the electrode chamber 5 has an electrolytic solution inlet for introducing the electrolytic solution into the electrode chamber 5 and an electrolytic solution outlet for drawing out the electrolytic solution from the electrode chamber 5 at the boundary with the outer frame (d). More specifically, the anode chamber 5a is provided with an anode electrolytic solution inlet for introducing the electrolytic solution into the anode chamber 5a and an anode electrolytic solution outlet for leading out the electrolytic solution to be led out from the anode chamber 5a. Similarly, the cathode chamber 5c is provided with a cathode electrolytic solution inlet for introducing the electrolytic solution into the cathode chamber 5c and a cathode electrolytic solution outlet for drawing out the electrolytic solution to be derived from the cathode chamber 5c.

In the present embodiment, the anode chamber 5a and the cathode chamber 5c may be provided with an internal distributor for uniformly distributing the electrolytic solution in the electrode surface inside the bipolar electrolytic cell 50 for water electrolysis. Further, the electrode chamber 5 may be provided with a baffle plate having a function of restricting the flow of liquid inside the bipolar electrolytic cell 50 for water electrolysis. Further, in the anode chamber 5a and the cathode chamber 5c, the concentration and temperature of the electrolytic solution in the bipolar electrolytic cell 50 for water electrolysis are made uniform, and the defoaming of the gas adhering to the electrode 2 and the diaphragm 4 is promoted. Therefore, a protrusion for creating a Karman vortex may be provided.

In the examples shown in FIGS. 1 and 2, a rectangular parallelepiped outer frame (d) in which the rectangular partition wall 1 and the rectangular diaphragm 4 are arranged in parallel and provided at the end edge of the partition wall 1 is provided. Since the inner surface of the partition wall 1 side is perpendicular to the partition wall 1, the shape of the electrode chamber 5 is a rectangular parallelepiped. The shape of the electrode chamber 5 is not limited to this, and may be appropriately deformed depending on the plan view shape of the partition wall 1 and the diaphragm 4, the angle formed by the inner surface of the outer frame (d) on the partition wall 2 side and the partition wall 2, and the like. Any shape may be used as long as the effect of the present invention can be obtained.

A header, which is a tube for distributing or collecting an electrolytic solution, is usually attached to the bipolar electrolytic cell 50 for water electrolysis, and an anode is provided below the outer frame (d) at the end edge of the partition wall 1. The chamber 5a is provided with an anode inlet header for containing the electrolytic solution, and the cathode chamber 5c is provided with a cathode inlet header for containing the electrolytic solution. Similarly, above the outer frame (d) at the edge of the partition wall 1, an anode outlet header for discharging the electrode liquid from the anode chamber 5a and a cathode outlet header for discharging the electrolytic solution from the cathode chamber 5c are provided. ing.
There are typically an internal header type and an external header type as an arrangement mode of the header attached to the multipolar electrolytic cell 50 for water electrolysis, but in the present invention, any type may be adopted. Well, it is not particularly limited.

In the bipolar electrolysis tank 50 for water electrolysis of the present embodiment, the electrolytic solution distributed at the anode inlet header is introduced into the anode chamber 5a through the anode electrolytic solution inlet, passes through the anode chamber 5a, and is used for anode electrolysis. It is drawn out from the anode chamber 5a through the liquid outlet and collected at the anode outlet header.

In the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, the convection generated in the electrolytic cell 5 due to the turbulence of the flow of gas and liquid in the electrolytic cell 5 is reduced, and the local rise in the temperature of the electrolytic cell is suppressed. Therefore, a plurality of rectifying plates 6 arranged in parallel to a given direction D1 along the partition wall 1 may be provided (see FIG. 2).

In the cell stack (a), the thickness of the secondary gasket (c) is preferably 10 to 40%, more preferably 15 to 35%, still more preferably 20% of the thickness of the bipolar element. ~ 30%.
As will be described later, the material of the outer frame (d) and the partition wall of the multipolar element 60 is stainless steel (SUS), steel, nickel or the like, and the material of the secondary gasket (c) is resin or the like.
The specific thickness of the secondary gasket (c) is determined according to the size and shape of the bipolar electrolytic cell 50 for water electrolysis, but is preferably 0.5 to 15 mm, more preferably 2 for example. It is 10 mm, more preferably 3 to 8 mm.
The sealing surface pressure of the secondary gasket (c) is preferably 10 times or more, more preferably 20 times or more, the maximum internal pressure of the bipolar electrolytic cell 50 for water electrolysis. The maximum internal pressure of the water electrolysis multipolar electrolytic cell 50 can be measured by a pressure gauge provided in the outlet flow path of the generated gas. The sealing surface pressure is determined according to the material of the primary and secondary gaskets (c), but is an approximate value obtained by dividing the load received by the cell stack from the hydraulic control mechanism (g) by the contact area of the secondary gasket (c). May be used as.

In the cell stack (a), the thickness of the primary gasket (b) is preferably 10% to 30%, more preferably 15% to 25%, and further preferably 18 in terms of compressibility during use. ~ 23%.
The compression rate of the primary gasket (b) refers to the shrinkage rate of the length of the primary gasket (b) in the stack direction compared before and after electrolysis.

The specific height of the primary gasket (b) is determined by the distance between the outer frames (d) of the adjacent bipolar elements and the thickness of the secondary gasket (c), and is, for example, 5 to 15 mm. It is preferably 8 to 12 mm, more preferably 8 to 12 mm.

Further, the depth of the groove structure (e) is preferably smaller than the height of the primary gasket (b), and specifically, it is preferably 50% to 95% of the height of the primary gasket (b). , More preferably 60% to 80%.

When the thickness of the primary gasket (b) and the depth of the groove structure (e) are within the above ranges, the electrolytic solution and generation occur even under high pressure conditions of 1 MPa or less and pressure fluctuations within 0 to 1 MPaG. There is no gas leakage, and the primary gasket (b) is unlikely to stick out or break.

− Septum −
The shape of the partition wall 1 in the present embodiment may be a plate-like shape having a predetermined thickness, but is not particularly limited.
The plan view shape of the partition wall 1 is not particularly limited, and may be a rectangle (square, rectangle, etc.) or a circle (circle, ellipse, etc.), and the rectangle may have rounded corners.
In one embodiment, the partition wall 1 and the outer frame (d) may be integrated by joining by welding or other methods. For example, a flange protruding from the partition wall 1 in a direction perpendicular to the plane of the partition wall 1 A portion (anode flange portion overhanging on the anode 2a side, a cathode flange portion overhanging on the cathode 2c side) may be provided, and the flange portion may be a part of the outer frame (d).

The partition wall 1 may be used so that the given direction D1 along the partition wall 1 is usually in the vertical direction. Specifically, as shown in FIG. 2, the partition wall 1 has a rectangular shape in a plan view. If, the given direction D1 along the partition wall 1 may be used so as to be in the same direction as the direction of one of the two facing sides. In the present specification, the vertical direction is also referred to as an electrolytic solution passing direction.

As the material of the partition wall 1, a material having conductivity is preferable from the viewpoint of realizing a uniform supply of electric power, and from the viewpoint of resistance and heat resistance, on stainless steel, steel, nickel, nickel alloy, mild steel, and nickel alloy. Nickel-plated ones are preferable.

-Electrodes-
In hydrogen production by water electrolysis of the present embodiment, reduction of energy consumption, specifically, reduction of electrolysis voltage is a big problem. Since this electrolytic voltage largely depends on the electrode 2, the performance of both electrodes 2 is important.

In addition to the theoretically required voltage for electrolysis of water, the electrolytic voltage of water electrolysis includes the overvoltage of the anode reaction (oxygen generation), the overvoltage of the cathode reaction (hydrogen generation), and the electrodes of the anode 2a and the cathode 2c. It is divided into voltage according to the distance between two. Here, the overvoltage means a voltage that needs to be excessively applied beyond the theoretical decomposition potential when a certain current is passed, and the value depends on the current value. When the same current is passed, power consumption can be reduced by using the electrode 2 having a low overvoltage.

In order to realize a low overvoltage, the requirements for the electrode 2 are high conductivity, high oxygen-evolving ability (or hydrogen-evolving ability), high wettability of the electrolytic solution on the surface of the electrode 2, and the like. Can be mentioned.

Even if an unstable current such as renewable energy is used as the electrode 2 for water electrolysis in addition to the low overvoltage, the base material and the catalyst layer of the electrode 2 are corroded, the catalyst layer is dropped off, and the electrode 2 is dissolved in the electrolytic solution. , It is difficult for the inclusions to adhere to the diaphragm 4.

As the electrode 2 in the present embodiment, a porous body is preferable in order to increase the surface area used for electrolysis and to efficiently remove the gas generated by electrolysis from the surface of the electrode 2. In particular, in the case of a zero-gap electrolytic cell, since it is necessary to defoam the gas generated from the back side of the contact surface with the diaphragm 4, the surface of the electrode 2 opposite to the surface in contact with the membrane must penetrate. Is preferable.

Examples of the porous body include plain weave mesh, punching metal, expanded metal, metal foam and the like.

The electrode 2 in the present embodiment may be the base material itself or may have a catalyst layer having high reaction activity on the surface of the base material, but it is preferable that the electrode 2 has a catalyst layer having high reaction activity on the surface of the base material. ..

The material of the base material is not particularly limited, but mild steel, stainless steel, nickel, and nickel-based alloys are preferable from the viewpoint of resistance to the usage environment.

The catalyst layer of the anode 2a preferably has a high oxygen-evolving ability, and nickel, cobalt, iron, a platinum group element, or the like can be used. These can form a catalyst layer as a simple substance of a metal, a compound such as an oxide, a composite oxide or an alloy composed of a plurality of metal elements, or a mixture thereof in order to realize desired activity and durability. An organic substance such as a polymer may be contained in order to improve durability and adhesiveness to a base material.

The catalyst layer of the cathode 2c is preferably one having a high hydrogen generating ability, and nickel, cobalt, iron, a platinum group element or the like can be used. These can form a catalyst layer as a simple substance of a metal, a compound such as an oxide, a composite oxide or an alloy composed of a plurality of metal elements, or a mixture thereof in order to realize desired activity and durability. Organic substances such as polymer materials may be contained in order to improve durability and adhesiveness to a base material.

As a method for forming a catalyst layer on a substrate, a spraying method such as a plating method or a plasma spraying method, a thermal decomposition method in which heat is applied after applying a precursor layer solution on the substrate, and a catalytic substance mixed with a binder component. Then, a method of immobilizing the material on the substrate and a vacuum film forming method such as a sputtering method can be mentioned.

-Outer frame (d)-
The shape of the outer frame (d) in the present embodiment is not particularly limited as long as the partition wall 1 can be bordered, but is provided with an inner surface along the direction perpendicular to the plane of the partition wall 1 over the outer extension of the partition wall 1. May be.
The shape of the outer frame (d) is not particularly limited and may be appropriately determined according to the plan view shape of the partition wall 1.

As the material of the outer frame (d), a material having conductivity is preferable, and from the viewpoint of alkali resistance and heat resistance, stainless steel, steel, nickel, nickel alloy, mild steel, and nickel alloy coated with nickel are used. preferable.

-Septum-
As the diaphragm 4 used in the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, an ion-permeable diaphragm 4 is used in order to separate the generated hydrogen gas and oxygen gas while conducting ions. .. As the ion-permeable diaphragm 4, an ion exchange membrane having an ion exchange ability and a porous membrane capable of permeating an electrolytic solution can be used. The ion-permeable diaphragm 4 preferably has low gas permeability, high ion conductivity, low electron conductivity, and high strength.

--Perforated membrane ---
The porous membrane has a plurality of fine through holes and has a structure in which the electrolytic solution can permeate through the diaphragm 4. Since the electrolytic solution permeates into the porous membrane to develop ionic conduction, it is very important to control the porous structure such as pore size, porosity, and hydrophilicity. On the other hand, it is required that not only the electrolytic solution but also the generated gas do not pass through, that is, it has a gas blocking property. From this point of view, it is important to control the porous structure.

The porous membrane has a plurality of fine through holes, and examples thereof include a polymer porous membrane, an inorganic porous membrane, a woven fabric, and a non-woven fabric. These can be produced by known techniques.
Examples of the method for producing a polymer porous membrane include a phase conversion method (micro phase separation method), an extraction method, a stretching method, a wet gel stretching method, and the like.

The porous membrane preferably contains a polymer material and hydrophilic inorganic particles, and the presence of the hydrophilic inorganic particles can impart hydrophilicity to the porous membrane.

--- Polymer material ---
Examples of the polymer material include polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polycarbonate, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / ethylene copolymer, and polyvinylidene fluoride. , Polytetrafluoroethylene, perfluorosulfonic acid, perfluorocarboxylic acid, polyethylene, polypropylene, polyphenylene sulfide, polyparaphenylene benzobisoxazole, polyketone, polyimide, polyetherimide and the like. Among these, polysulfone, polyethersulfone, polyphenylsulfone, polyphenylene sulfide, and polytetrafluoroethylene are preferable, and polysulfone is more preferable. These may be used alone or in combination of two or more.

It is preferable to control the pore size of the porous membrane in order to obtain appropriate membrane characteristics such as separation ability and strength. When used for water electrolysis, it is preferable to control the pore size of the porous film from the viewpoint of preventing mixing of oxygen gas generated from the anode 2a and hydrogen gas generated from the cathode 2c and reducing voltage loss in electrolysis. ..
The larger the average pore size of the porous membrane, the larger the permeation amount of the porous membrane per unit area. In particular, in electrolysis, the ion permeability of the porous membrane becomes good, and the voltage loss tends to be easily reduced. Further, the larger the average pore size of the porous membrane, the smaller the contact surface area with alkaline water, so that the deterioration of the polymer tends to be suppressed.
On the other hand, the smaller the average pore size of the porous membrane, the higher the separation accuracy of the porous membrane, and the better the gas barrier property of the porous membrane in electrolysis. Further, when hydrophilic inorganic particles having a small particle size, which will be described later, are supported on the porous membrane, they can be firmly held without being chipped. As a result, the high holding ability of the hydrophilic inorganic particles can be imparted, and the effect can be maintained for a long period of time.

From this point of view, in the porous membrane of the present embodiment, the average pore diameter is preferably in the range of 0.1 to 1.0 μm. As long as the pore size is in this range, the porous membrane can achieve both excellent gas blocking property and high ion permeability. Further, it is preferable that the pore size of the porous membrane is controlled in the temperature range actually used. Therefore, for example, when used as an electrolytic diaphragm 4 in an environment of 90 ° C., it is preferable to satisfy the above-mentioned pore diameter range at 90 ° C. Further, it is more preferable that the porous membrane has an average pore size of 0.1 to 0.5 μm as a range in which a diaphragm 4 for water electrolysis can exhibit better gas blocking property and high ion permeability.

The average pore size of the porous membrane can be measured by the following method.
The average pore size of the porous membrane means the average pore size measured by the following method using an integrity tester (“Sartorius Stedim Japan Co., Ltd.,“ Sartocheck Junior BP-Plus ”). First, the porous membrane is cut into a predetermined size including the core material, and this is used as a sample. This sample is set in an arbitrary pressure-resistant container, and the inside of the container is filled with pure water. Next, the pressure-resistant container is held in a constant temperature bath set to a predetermined temperature, and the measurement is started after the inside of the pressure-resistant container reaches the predetermined temperature. When the measurement starts, the upper surface side of the sample is pressurized with nitrogen, and the numerical values of the pressure and the permeation flow rate when pure water permeates from the lower surface side of the sample are recorded. The average permeability hole diameter can be obtained from the following Hagen-Poiseuille equation using the gradient between the pressure and the permeability flow rate at which the pressure is between 10 kPa and 30 kPa.
Average permeable hole diameter (m) = {32ηLμ ₀ / (εP)} ^0.5
Here, η is the viscosity of water (Pa · s), L is the thickness of the porous film (m), μ ₀ is the apparent flow velocity, and μ ₀ (m / s) = flow rate (m ³ / s) / flow. The road area (m ² ). Further, ε is the porosity and P is the pressure (Pa).

The diaphragm 4 has a porosity of a porous membrane from the viewpoints of gas barrier property, maintenance of hydrophilicity, prevention of deterioration of ion permeability due to adhesion of bubbles, and long-term stable electrolytic performance (low voltage loss, etc.). It is preferable to control.
From the viewpoint of achieving both gas breaking property and low voltage loss at a high level, the lower limit of the porosity of the porous membrane is preferably 30% or more, more preferably 35% or more, and more preferably 40% or more. Is even more preferable. The upper limit of the porosity is preferably 70% or less, more preferably 65% or less, and further preferably 55% or less. When the porosity of the porous membrane is not more than the above upper limit value, ions easily permeate through the membrane, and the voltage loss of the membrane can be suppressed.

The porosity of the porous membrane refers to the open porosity determined by the Archimedes method, and can be determined by the following formula.
Porosity P (%) = ρ / (1 + ρ) x 100
Here, ρ = (W3-W1) / (W3-W2), W1 is the dry mass (g) of the porous membrane, W2 is the underwater mass (g) of the porous membrane, and W3 is the satiety mass of the porous membrane (W3). g).

As a method for measuring the porosity, a porous membrane washed with pure water is cut into three pieces having a size of 3 cm × 3 cm and used as a measurement sample. First, W2 and W3 of the sample are measured. Then, the porous membrane is allowed to stand for 12 hours or more in a dryer set at 50 ° C. to dry, and W1 is measured. Then, the porosity is obtained from the values of W1, W2, and W3. The porosity is obtained for three samples, and the arithmetic mean value thereof is defined as the porosity P.

The thickness of the porous membrane is not particularly limited, but is preferably 100 to 700 μm, more preferably 100 to 600 μm, and even more preferably 200 to 600 μm.
When the thickness of the porous membrane is not less than the above lower limit value, it is difficult to tear due to piercing or the like, and it is difficult to short-circuit between the electrodes. In addition, the gas barrier property becomes good. Further, when it is not more than the above upper limit value, the voltage loss is unlikely to increase. In addition, the influence of variation in the thickness of the porous membrane is reduced.
Further, when the thickness of the diaphragm is 100 μm or more, it is difficult to tear due to piercing or the like, and it is difficult to short-circuit between the electrodes. In addition, the gas barrier property becomes good. When it is 600 μm or less, the voltage loss is unlikely to increase. In addition, the influence of variation in the thickness of the porous membrane is reduced.
When the thickness of the porous membrane is 250 μm or more, more excellent gas blocking property can be obtained, and the strength of the porous membrane against impact is further improved. From this viewpoint, the lower limit of the thickness of the porous membrane is more preferably 300 μm or more, further preferably 350 μm or more, and further preferably 400 μm or more. On the other hand, when the thickness of the porous membrane is 700 μm or less, the resistance of the electrolytic solution contained in the pores during operation does not hinder the permeability of ions, and more excellent ion permeability can be maintained. From this point of view, the upper limit of the thickness of the porous membrane is more preferably 600 μm or less, further preferably 550 μm or less, and further preferably 500 μm or less.

--- Hydrophilic inorganic particles ---
The porous membrane preferably contains hydrophilic inorganic particles in order to exhibit high ion permeability and high gas blocking property. The hydrophilic inorganic particles may be attached to the surface of the porous membrane, or may be partially embedded in the polymer material constituting the porous membrane. Further, when the hydrophilic inorganic particles are encapsulated in the voids of the porous membrane, it becomes difficult to separate from the porous membrane, and the performance of the porous membrane can be maintained for a long time.

Examples of the hydrophilic inorganic particles include oxides or hydroxides of zirconium, bismuth, and cerium; oxides of Group IV elements of the Periodic Table; nitrides of Group IV elements of the Periodic Table, and IV of the Periodic Table. At least one inorganic substance selected from the group consisting of carbides of group elements can be mentioned. Among these, from the viewpoint of chemical stability, oxides of zirconium, bismuth and cerium, oxides of Group IV elements of the Periodic Table are more preferable, oxides of zirconium, bismuth and cerium are more preferable, and zirconium oxide is preferable. Even more preferable.

The form of the hydrophilic inorganic particles is preferably a fine particle shape.

--Porosity support ---
When a porous membrane is used as the diaphragm 4, the porous membrane may be used together with the porous support. It is preferable that the porous film has a structure in which the porous support is embedded, and more preferably, it is a structure in which the porous film is laminated on both sides of the porous support. Further, the structure may be such that the porous membranes are symmetrically laminated on both sides of the porous support.

Examples of the porous support include a mesh, a porous film, a non-woven fabric, a woven fabric, a non-woven fabric, and a composite cloth including a woven fabric contained in the non-woven fabric. These may be used alone or in combination of two or more. More preferred embodiments of the porous support include, for example, a mesh substrate made of a monofilament of polyphenylene sulfide, or a composite fabric containing a nonwoven fabric and a woven fabric contained therein.

--Ion exchange membrane ---
The ion exchange membrane includes a cation exchange membrane that selectively permeates a cation and an anion exchange membrane that selectively permeates an anion, and any exchange membrane can be used.
The material of the ion exchange membrane is not particularly limited, and known materials can be used. For example, a fluorine-containing resin or a modified resin of a polystyrene / divinylbenzene copolymer can be preferably used. In particular, a fluorine-containing ion exchange membrane is preferable because it is excellent in heat resistance and chemical resistance.

Examples of the fluorine-containing ion exchange membrane include those having a function of selectively permeating ions generated during electrolysis and containing a fluorine-containing polymer having an ion exchange group. The fluorinated polymer having an ion exchange group as used herein means a fluorinated polymer having an ion exchange group or an ion exchange group precursor that can become an ion exchange group by hydrolysis. For example, a polymer having a main chain of a fluorinated hydrocarbon, having a functional group that can be converted into an ion exchange group by hydrolysis or the like as a pendant side chain, and capable of melt processing can be mentioned.

The molecular weight of the fluorine-containing copolymer is not particularly limited, but the precursor is measured by the melt flow index (MFI) value measured in accordance with ASTM: D1238 (measurement conditions: temperature 270 ° C., load 2160 g). It is preferably 0.05 to 50 (g / 10 minutes), more preferably 0.1 to 30 (g / 10 minutes).

Examples of the ion exchange group contained in the ion exchange film include a cation exchange group such as a sulfonic acid group, a carboxylic acid group and a phosphoric acid group, and an anion exchange group such as a quaternary ammonium group.

The ion exchange membrane can impart excellent ion exchange ability and hydrophilicity by adjusting the equivalent mass EW of the ion exchange group. In addition, it can be controlled to have many smaller clusters (microparts in which ion exchange groups coordinate and / or adsorb water molecules), and tends to improve alkali resistance and ion selective permeability.
This equivalent mass EW can be measured by substituting the ion exchange membrane with a salt and back-titrating the solution with an alkaline or acid solution. The equivalent mass EW can be adjusted by the copolymerization ratio of the monomer as a raw material, the selection of the monomer type, and the like.
The equivalent mass EW of the ion exchange membrane is preferably 300 or more from the viewpoint of hydrophilicity and water resistance of the membrane, and preferably 1300 or less from the viewpoint of hydrophilicity and ion exchange ability.

The thickness of the ion exchange membrane is not particularly limited, but is preferably in the range of 5 to 300 μm from the viewpoint of ion permeability and strength.

Surface treatment may be applied for the purpose of improving the hydrophilicity of the surface of the ion exchange membrane. Specific examples thereof include a method of coating hydrophilic inorganic particles such as zirconium oxide and a method of imparting fine irregularities on the surface.

The ion exchange membrane is preferably used together with the reinforcing material from the viewpoint of film strength. The reinforcing material is not particularly limited, and examples thereof include general non-woven fabrics, woven fabrics, and porous membranes made of various materials. The porous membrane in this case is not particularly limited, but a stretched and porous PTFE membrane is preferable.

-Septal fall prevention mechanism-
In the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, the outer frame (d) bordering the partition wall 1 is provided with a fall prevention mechanism (h) for the diaphragm. The diaphragm fall prevention mechanism (h) is at least one or more insulating supports that support the weight of the diaphragm and prevent the diaphragm from falling when the stack pressure becomes zero during assembly and replacement.

The fall prevention mechanism (h) of the diaphragm preferably has a simple structure such as a pin or a bolt to fix the diaphragm to the outer frame (d). In that case, a pin hole or a bolt hole is provided in the outer frame, a hole is similarly made in the diaphragm, and the diaphragm is sandwiched between the outer frame and the fall prevention mechanism (h).

The fall prevention mechanism (f) of the diaphragm needs to be provided on the outside of the primary gasket (b). Further, since it affects the sealing property of the secondary gasket, it is preferable to provide it inside the secondary gasket. That is, it is preferable that the fall prevention mechanism (f) of the diaphragm is installed between the primary gasket (b) and the secondary gasket (c).

((Zero gap structure))
In the multipolar element 60 in the zero gap type cell, a spring which is an elastic body is arranged between the electrode 2 and the partition wall 1 as a means for reducing the distance between the electrodes, and the spring supports the electrode 2. Is preferable. For example, in the first example, a spring made of a conductive material may be attached to the partition wall 1, and an electrode 2 may be attached to the spring. Further, in the second example, a spring may be attached to the electrode rib attached to the partition wall 1, and the electrode 2 may be attached to the spring. When adopting a form using such an elastic body, the strength of the spring, the number of springs, the shape, etc. are appropriately adjusted as necessary so that the pressure of the electrode 2 in contact with the diaphragm 4 does not become non-uniform. There is a need to.

-Electrode chamber-
In the bipolar electrolytic cell 50 for water electrolysis in the present embodiment, as shown in FIG. 2, the partition wall 1, the outer frame (d), and the diaphragm 4 define an electrode chamber 5 through which the electrolytic solution passes.

In the present embodiment, an internal header type and an external header type can be adopted as the arrangement mode of the header 10 of the bipolar electrolytic cell. For example, in the case of the illustrated example, the space occupied by the anode 2a and the cathode 2c itself. May be a space inside the electrode chamber 5. Further, in particular, when the gas-liquid separation box is provided, the space occupied by the gas-liquid separation box may also be the space inside the electrode chamber 5.

-Rectifying plate-
In the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, the straightening vane 6 (anodic rectifying plate, cathode straightening vane) is attached to the partition wall 1, and the straightening vane 6 is physically connected to the electrode 2. preferable. According to such a configuration, the straightening vane 6 serves as a support for the electrode 2, and it is easy to maintain the zero gap structure Z.
Here, the rectifying plate 6 may be provided with the electrode 2, and the rectifying plate 6 may be provided with the current collector 2r, the conductive elastic body 2e, and the electrode 2 in this order.
In the double-pole electrolytic cell 50 for water electrolysis of the above example, a structure in which the rectifying plate 6-the current collector 2r-the conductive elastic body 2e-the electrode 2 are stacked in this order is adopted in the cathode chamber 5c, and the anode chamber is adopted. In 5a, a structure in which the straightening vanes 6 and the electrodes 2 are stacked in this order is adopted.

In the above-mentioned example of the double-pole electrolytic cell 50 for water electrolysis, the structure of the above-mentioned "rectifying plate 6-collector 2r-conductive elastic body 2e-electrode 2" is adopted in the cathode chamber 5c, and the anode chamber 5a is adopted. However, the structure of the above-mentioned "rectifying plate 6-electrode 2" is adopted in the present invention, but the present invention is not limited to this, and the "rectifying plate 6-collector 2r-conductive elastic body 2e" is also used in the anode chamber 5a. -The "electrode 2" structure may be adopted.

The straightening vane 6 (anode straightening vane, cathode straightening vane) preferably has not only a role of supporting the anode 2a or the cathode 2c but also a role of transmitting a current from the partition wall 1 to the anode 2a or the cathode 2c.

In the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, it is preferable that at least a part of the straightening vane 6 has conductivity, and it is more preferable that the entire straightening vane 6 has conductivity. According to such a configuration, it is possible to suppress an increase in the cell voltage due to electrode deflection.

As the material of the straightening vane 6, a conductive metal is generally used. For example, nickel-plated mild steel, stainless steel, nickel and the like can be used.

The distance between adjacent anode rectifying plates or the distance between adjacent cathode rectifying plates is determined in consideration of the electrolytic pressure, the pressure difference between the anode chamber 5a and the cathode chamber 5c, and the like.

The length of the straightening vane 6 (anode straightening vane, cathode straightening vane) may be appropriately determined according to the size of the partition wall 1.
The height of the rectifying plate 6 is the distance from the partition wall 1 to each flange portion, the thickness of the primary gasket (b), the thickness of the electrodes 2 (anode 2a, cathode 2c), and between the anode 2a and the cathode 2c. It may be appropriately determined according to the distance and the like.
The thickness of the straightening vane 6 may be 0.5 to 5 mm in consideration of cost, manufacturability, strength, etc., and those having 1 to 2 mm are easy to use, but are not particularly limited.

-Primary gasket-
In the water electrolysis multi-pole electrolytic cell 50 of the present embodiment, the primary gasket (b) has a groove structure (e) provided in the outer frame (d) edging the partition wall 1 and the primary gasket (b). At least a part of the outer peripheral surface is intermittently and preferably stored in a state where the outer peripheral surface of the primary gasket (b) is in contact with the side wall (f) of the groove structure (e) over the entire circumference. To.
The diaphragm 4 is preferably sandwiched between the primary gasket (b) and the adjacent outer frame (d) as shown in FIG. 2A, but the diaphragm 4 is sandwiched between the primary gaskets as shown in FIG. 2B. It may be a structure to be used.

The primary gasket (b) is used on both the cathode side surface and the anode side surface of the diaphragm, and the primary gasket (b) generates an electrolytic solution between the multipolar element 60 and the diaphragm 4 and between the multipolar elements 60. It is used to seal against gas, and can prevent leakage of the electrolytic solution and generated gas to the outside of the electrolytic cell and gas mixing between the bipolar chambers.

The general structure of the primary gasket (b) is a quadrangular shape or an annular shape in which the electrode surface is hollowed out so as to match the surface of the element in contact with the frame. The diaphragm 4 can be stacked between the elements by sandwiching the diaphragm 4 with two such gaskets.

The material of the primary gasket (b) is not particularly limited, and a known rubber material having an insulating property can be selected.
Specific examples of the rubber material include natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), silicone rubber (SR), and ethylene. Use rubber materials such as -propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), fluororubber (FR), isobutylene-isoprene rubber (IIR), urethane rubber (UR), and chlorosulfonated polyethylene rubber (CSM). be able to. Among these, ethylene-propylene-diene rubber (EPDM) and fluororubber (FR) are particularly preferable from the viewpoint of elastic modulus and alkali resistance.

A reinforcing material may be embedded in the primary gasket (b). As a result, it is possible to prevent the primary gasket (b) from being crushed when it is sandwiched between the frames and pressed during stacking, and it is possible to easily prevent damage.
Known metal materials, resin materials, carbon materials and the like can be used as such reinforcing materials, and specifically, metals such as nickel and stainless steel, resins such as nylon, polypropylene, PVDF, PTFE and PPS, carbon particles and carbon. Examples include carbon materials such as fibers.

The size of the primary gasket (b) is not particularly limited and may be designed according to the dimensions of the electrode chamber 5 and the diaphragm 4, but the preferred conditions are as described above.

The elastic modulus of the primary gasket (b) is in the range of 30 MPa or less in terms of tensile stress at the time of 100% deformation, and is more preferably in the range of 5.0 to 20 MPa from the viewpoint of sealing characteristics and pressure resistance.
The tensile stress can be measured according to JIS K6251. For example, Autograph AG manufactured by Shimadzu Corporation may be used.

-Secondary gasket-
In the multipolar electrolytic cell 50 for water electrolysis of the present embodiment, it is preferable that the secondary gasket (c) is sandwiched between the outer frames (d) bordering the partition wall 1.
The secondary gasket (c) is installed between the adjacent bipolar elements 60 on the outer peripheral side (atmosphere side) of the primary gasket (b) and the diaphragm 4, and allows water to pass through the porous film to form the primary gasket (b). It is used to seal the electrolytic solution that has flowed out to the outside, and can prevent the electrolytic solution from leaking to the outside of the electrolytic tank.

The general structure of the secondary gasket (c) is a quadrangular shape or an annular shape in which the electrode surface is hollowed out according to the surface of the element in contact with the frame. By sandwiching such a gasket between the outer frames (d), the gap between the outer frames (d) is appropriately maintained, the outer frames (d) are prevented from coming into contact with each other and short-circuited, and the gasket is installed inside 1 An appropriate compression ratio can be given to the next gasket (b).
The secondary gasket (c) supports compression in the stacking direction and can keep the distance in the gap between adjacent outer frames (d) during stacking within the range of 0.5 mm to 5 mm.

The material of the secondary gasket (c) is not particularly limited, and a known resin material having insulating properties can be selected.
Specific examples of the resin material include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE), and chlorotrifluorethylene / ethylene. Fluororesin materials such as copolymer (ECTFE) and resin materials such as polyphenylene sulfide (PPS), polyethylene, polyimide, and polyacetal can be used. Among these, polytetrafluoroethylene (PTFE) is particularly preferable from the viewpoint of elastic modulus and alkali resistance.

The secondary gasket (c) is characterized in that the volume resistivity at the electrolytic temperature is 1 MΩ · cm or more.
The volume resistivity can be measured in accordance with JIS K6911 standard. For example, a super insulation meter manufactured by Hioki Electric Co., Ltd. may be used.

The size of the secondary gasket (c) is not particularly limited and may be designed according to the dimensions of the electrode chamber 5 and the diaphragm 4, but the width is preferably 10 to 40 mm. The thickness is as described above.

The secondary gasket (c) is characterized by having a Young's modulus of 200 MPa or more.
Young's modulus can be measured in accordance with JIS K7161 standard. For example, a precision universal testing machine (autograph) manufactured by Shimadzu Corporation may be used.

Further, the ratio E / σ of the Young's modulus E of the secondary gasket (c) and the tensile stress σ at the time of 100% deformation of the primary gasket (b) is E / σ ≧ 10.

-Header-
The bipolar electrolytic cell 50 for water electrolysis has a cathode chamber 5c and an anode chamber 5a for each electrolysis cell 65. In order to continuously perform the electrolysis reaction in the multipolar electrolytic cell 50 for water electrolysis, electrolysis in which the cathode chamber 5c and the anode chamber 5a of each electrolysis cell 65 sufficiently contain the raw materials consumed by electrolysis. It is necessary to continue to supply the liquid.

The electrolytic cell 65 is connected to an electrolytic solution supply / discharge pipe called a header common to the plurality of electrolytic cells 65. Generally, the anode liquid distribution tube is called an anode inlet header, the cathode liquid distribution tube is called a cathode inlet header, the anode liquid collecting tube is called an anode outlet header, and the cathode liquid collecting tube is called a cathode outlet header. The electrolytic cell 65 is connected to the liquid distribution pipe for each electrode and the liquid collection pipe for each electrode through a hose or the like.

The material of the header is not particularly limited, but it is necessary to use a header that can sufficiently withstand the corrosiveness of the electrolytic solution used and the operating conditions such as pressure and temperature. As the material of the header, iron, nickel, cobalt, PTFE, ETFE, PFA, polyvinyl chloride, polyethylene or the like may be adopted.

In the present embodiment, the range of the electrode chamber 5 varies depending on the detailed structure of the outer frame (d) provided at the outer end of the partition wall 1, and the detailed structure of the outer frame (d) is changed to the outer frame (d). It may differ depending on the arrangement mode of the attached header (tube for distributing or collecting the electrolytic solution). The internal header type and the external header type are typical as the arrangement mode of the header of the bipolar electrolytic cell 50 for water electrolysis.

--Internal header ---
The internal header type refers to a type in which a bipolar electrolytic cell 50 for water electrolysis and a header (a tube for distributing or collecting an electrolytic solution) are integrated.

In the internal header type multi-pole electrolytic cell, more specifically, the anode inlet header and the cathode inlet header are provided in the partition wall 1 and / or in the lower portion in the outer frame (d), and are perpendicular to the partition wall 1. The anode outlet header and the cathode outlet header are provided so as to extend in the direction, and the anode outlet header and the cathode outlet header are provided in the partition wall 1 and / or in the upper part in the outer frame (d), and extend in the direction perpendicular to the partition wall 1. It is provided to do so.

The anode inlet header, the cathode inlet header, the anode outlet header, and the cathode outlet header inherently possessed by the internal header type multi-pole electrolytic cell are collectively referred to as an internal header.

In the example of the internal header type, the anode inlet header and the cathode inlet header are provided in a part of the lower portion of the outer frame (d) at the edge of the partition wall 1, and similarly, the same. An anode outlet header and a cathode outlet header are provided in a part of the outer frame (d) located at the upper end of the partition wall 1.

--External header ---
The external header type refers to a type in which the bipolar electrolytic cell 50 for water electrolysis and the header (the tube for distributing or collecting the electrolytic solution) are independent.

In the external header type multi-pole electrolytic cell, the anode inlet header and the cathode inlet header run in parallel with the water electrolysis multi-pole electrolytic cell 50 in the direction perpendicular to the current-carrying surface of the electrolytic cell 65. It is provided independently. The anode inlet header and the cathode inlet header are connected to each electrolytic cell 65 by a hose.

External header type The anode inlet header, cathode inlet header, anode outlet header, and cathode outlet header that are externally connected to the multi-pole electrolytic cell are collectively referred to as an external header.
In the example of the external header type, the luminal member is installed in the header through hole provided in the lower portion of the outer frame (d) at the end edge of the partition wall 1, and the luminal member is formed. In the header through hole provided in the upper portion of the outer frame (d) on the edge of the partition wall 1, which is connected to the anode inlet header and the cathode inlet header, as well. A luminal member (eg, hose, tube, etc.) is installed and the luminal member is connected to the anode outlet header and the cathode outlet header.

The internal header type and the external header type multipolar electrolytic cell 50 for water electrolysis may have a gas-liquid separation box for separating the gas generated by electrolysis and the electrolytic solution inside. The mounting position of the gas-liquid separation box is not particularly limited, but may be mounted between the anode chamber 5a and the anode outlet header, or between the cathode chamber 5c and the cathode outlet header.

The surface of the gas-liquid separation box may be coated with a coating material that can sufficiently withstand the corrosiveness of the electrolytic solution and operating conditions such as pressure and temperature. As the material of the coating material, an insulating material may be adopted for the purpose of increasing the electric resistance of the leakage current circuit inside the electrolytic cell. EPDM, PTFE, ETFE, PFA, polyvinyl chloride, polyethylene or the like may be adopted as the material of the coating material.

<Electrolyzer for water electrolysis>
FIG. 3 shows an outline of the electrolyzer for water electrolysis 70.
The electrolyzer for water electrolysis 70 of the present embodiment comprises a bipolar electrolytic tank 50 for water electrolysis of the present embodiment, a liquid feed pump 71 for circulating an electrolytic solution, and an electrolytic solution and hydrogen and / or oxygen. It has a gas-liquid separation tank 72 for separation and a water replenisher 73 for replenishing water consumed by electrolysis.

According to the water electrolysis electrolytic cell 70 of the present embodiment, the effect of the water electrolysis bipolar electrolytic cell 50 of the present embodiment can be obtained.
That is, according to the present embodiment, it is possible to obtain a bipolar electrolyzer for water electrolysis having a long life even when used under conditions of a variable power source or a high frequency of operation stoppage.

Hereinafter, the components of the electrolyzer for water electrolysis 70 of the present embodiment will be described.

-Liquid pump-
The liquid feed pump 71 used in the present embodiment is not particularly limited and may be appropriately defined.

-Gas and liquid separation tank-
The gas-liquid separation tank 72 used in the present embodiment is a hydrogen separation tank 72h that separates the hydrogen gas generated in the cathode chamber 5c and the electrolytic solution, and oxygen that separates the oxygen gas generated in the anode chamber 5a and the electrolytic solution. Includes separation tank 72o.
The hydrogen separation tank 72h is connected to the cathode chamber 5c, and the oxygen separation tank 72o is connected to the anode chamber 5a for use.

What is discharged from the electrolytic cell 65 in a state where the electrolytic solution and the generated gas are mixed is flowed into the gas-liquid separation tank 72. If the gas-liquid separation is not properly performed, oxygen gas and hydrogen gas are mixed when the electrolytic solutions of the cathode chamber 5c and the anode chamber 5a are mixed, and the purity of the gas is lowered. In the worst case, there is a risk of forming a roar.

The gas and the electrolytic solution that have flowed into the gas-liquid separation tank 72 are separated into the gas phase in the upper layer of the tank and the electrolytic solution in the liquid phase in the lower layer of the tank. The degree of gas-liquid separation is determined by the line bundle of the electrolytic solution in the gas-liquid separation tank 72, the floating speed of the generated gas bubbles, and the residence time in the gas-liquid separation tank 72.

After the gas is separated, the electrolytic solution flows out from the outlet below the tank and flows into the electrolytic cell 65 again to form a circulation path. Since both oxygen and hydrogen gas discharged from the discharge port above the tank contain alkaline mist, excess mist such as a mist separator and a cooler is liquefied and separated into gas and liquid downstream of the discharge port. It is preferable to attach a device that can be returned to the tank 72.

The gas-liquid separation tank 72 may be provided with a liquid level gauge in order to grasp the liquid level height of the electrolytic solution stored inside.

Further, it is preferable that the gas-liquid separation tank 72 is provided with a pressure release valve. As a result, even if the pressure rises due to the gas generated by electrolysis, the pressure can be safely lowered when the design pressure is exceeded.

The inflow port to the gas-liquid separation tank 72 is preferably located on the upper surface of the electrolytic solution surface in order to improve the gas-liquid separation property, but is not limited thereto.
For the purpose of preventing the liquid level in the electrolytic cell from dropping when the circulation is stopped, it is preferable that the electrolytic liquid level in the gas-liquid separation tank 72 is higher than the upper surface of the electrolytic cell, but the present invention is not limited to this.
It is preferable, but not limited to, a shutoff valve to be provided between the electrolytic cell 65 and the gas-liquid separation tank 72.

An alkali-resistant metal such as nickel is used as the material of the gas-liquid separation tank 72. On the other hand, when a general-purpose metal such as iron is used as the tank housing material, the electrolytic solution contact surface inside the tank may be coated with a fluororesin or the like. The material of the separation tank 72 is not limited.

The capacity of the gas-liquid separation tank 72 is preferably small in consideration of the installation volume, but if the volume is too small, the pressure difference between the cathode 2c and the anode 2a becomes large, or the electrolytic current value fluctuates. Since the liquid level in the tank fluctuates, it is necessary to take this fluctuation into consideration.
Similarly, when the height of the tank is low, it is easily affected by the above fluctuations, so it is preferable to increase the height of the tank.

-Water replenisher-
The water replenisher 73 used in the present embodiment is not particularly limited and may be appropriately defined.
As the water, general clean water may be used, but in consideration of long-term operation, it is preferable to use ion-exchanged water, RO water, ultrapure water, or the like.

-Other-
The water electrolysis electrolytic device 70 of the present embodiment includes a rectifier 74, an oxygen concentration meter 75, and hydrogen in addition to the water electrolysis multi-pole electrolytic tank 50, the liquid feed pump 71, the gas-liquid separation tank 72, and the water replenisher 73. A densitometer 76, a flow meter 77, a pressure gauge 78, a heat exchanger 79, and a pressure control valve 80 may be provided.

Further, it is preferable that the electrolyzer for water electrolysis 70 of the present embodiment further includes a detector that detects the stop of the power supply when the power supply is stopped, and a controller that automatically stops the liquid feed pump. By providing a detector and a controller, it becomes possible to efficiently reduce the influence of self-discharge without human operation even under a power source having a large fluctuation such as renewable energy.

Although the bipolar electrolysis tank for water electrolysis and the electrolysis device for water electrolysis of the embodiment of the present invention have been exemplified with reference to the drawings, the bipolar electrolysis tank for water electrolysis and the electrolysis for water electrolysis of the present invention have been described above. The device is not limited to the above example, and modifications can be made to the above embodiments as appropriate.

Since the multi-pole electrolytic cell for water electrolysis of the present invention has a long life even when used under a variable power source or a condition where the operation is frequently stopped, it has a long life even when operated under a variable power source such as renewable energy. It can be operated stably over the years.

(A) Cell stack (b) Primary gasket (c) Secondary gasket (d) Outer frame (e) Groove structure (f) Side wall (g) Hydraulic control mechanism (h) Diaphragm fall prevention mechanism 1 partition wall 2 electrode 2a anode 2c cathode 2e conductive elastic body 2r current collector 4 diaphragm 5 electrode chamber 5a anode chamber 5c cathode chamber 6 rectifying plate 50 multi-pole electrolytic tank for water electrolysis 51a anode terminal element 51c cathode terminal element 60 multi-polar element 65 electrolytic cell 70 Electrolyzer 71 Liquid transfer pump 72 Gas-liquid separation tank 72h Hydrogen separation tank 72o Oxygen separation tank 73 Water replenisher 74 Rectifier 75 Oxygen concentration meter 76 Hydrogen concentration meter 77 Flow meter 78 Pressure gauge 79 Heat exchanger 80 Pressure control valve D1 Partition Given direction along (electrolyte passage direction)
Z zero gap structure

Claims (14)

An anode terminal element with an anode and
A cathode terminal element with a cathode and
A plurality of duplexers located between the anode terminal element and the cathode terminal element, comprising an anode, a cathode, a partition wall separating the anode and the cathode, and an outer frame (d) edging the partition wall. Polar element and
With the cell stack (a) in which the microporous diaphragm disposed between the adjacent elements is stacked via a gasket;
With a hydraulic control mechanism (g) that applies surface pressure between the gasket and the diaphragm, and between the gasket and each of the elements;
It is a multi-pole electrolytic cell for water electrolysis equipped with
Located outside the primary gasket (b) that seals the electrolytic solution and the generated gas between at least one pair of the elements, and outside the sealing range of the primary gasket (b). An alkaline water electrolytic cell, characterized in that it is provided with a secondary gasket (c) for preventing leakage of the electrolytic cell that has flowed out to the outside of the electrolytic cell. The alkaline water electrolytic cell according to claim 1, wherein the primary gasket (b) is a rubber gasket and the secondary gasket (c) is a high-strength gasket. The alkaline water electrolytic cell according to claim 1 or 2, wherein the primary gasket (b) has a tensile stress σ at the time of 100% deformation of 30 MPa or less. The alkaline water electrolytic cell according to any one of claims 1 to 3, wherein the secondary gasket (c) has a Young's modulus E of 200 MPa or more. Any of claims 1 to 4, wherein the ratio E / σ of the Young's modulus E of the secondary gasket (c) and the tensile stress σ at the time of 100% deformation of the primary gasket (b) is E / σ ≧ 10. The multipolar electrolytic cell for water electrolysis according to item 1. The outer frame (d) of the multipolar element is provided with a groove structure (e) for installing the primary gasket (b), and the depth of the groove structure (e) is such that the primary gasket is installed. The aspect according to any one of claims 1 to 5, characterized in that the height is smaller than the height of (b), and at least the side wall (f) is provided on the outer peripheral surface side of the primary gasket (b). Alkaline water electrolytic cell. The alkaline water electrolysis according to claim 6, wherein the groove structure (e) has a shape in which the side wall (f) and at least a part of the outer peripheral surface of the primary gasket (b) are in contact with each other. Tank. The alkaline water electrolytic cell according to claim 6 or 7, wherein the groove structure (e) further has a side wall on the inner peripheral surface side of the primary gasket (b). The alkaline water electrolytic cell according to any one of claims 1 to 8, wherein the secondary gasket (c) has an insulating property. The alkaline water electrolytic cell according to claim 9, wherein the secondary gasket (c) has a volume resistance of 1 MΩ · cm or more at an electrolytic temperature. The secondary gasket (c) is characterized in that it supports compression in the stacking direction and keeps the distance between the outer frames (d) of the adjacent elements in the range of 0.5 mm to 5 mm during stacking. Item 2. The alkaline water electrolytic cell according to any one of Items 1 to 10. The alkaline water electrolytic cell according to any one of claims 1 to 11, wherein the stack pressure is controlled by hydraulic control of the plurality of the bipolar electrolytic cells. The alkaline water electrolytic cell according to any one of claims 1 to 12, wherein the multipolar element has a fall prevention mechanism (f) for the diaphragm in the outer frame (d). The alkaline water electrolytic cell according to claim 13, wherein the fall prevention mechanism (f) is installed between the primary gasket (b) and the secondary gasket (c).

Images