JP2000178781A - Electrolytic cell and fixed pin used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate assembling and disassembling work and to prevent the slippage of each part, the damage and the degradation of a solid electrolyte membrane by penetrating a freely detachable flexible electrode B and an elastic mat in contact with the electrode B from the contact surface side of the electrode B with the solid electrolyte membrane to engage and fix with a porous collector plate. SOLUTION: The flexible electrode 6 and a metal made elastic mat 7 are provided respectively on the front surface and the rear surface of a cathode section frame. The flexible electrode 6 and the elastic mat 7 are fixed to a hole part of the porous cathode collector plate 8 with a fixing pin penetrating from the front surface in contact with the ion exchange membrane. An enlarged head part of the fixing pin 12 has an action to press the flexible cathode 6 and the tip part is engaged with the hole of the porous cathode collector plate 8 through the neck part and is composed of a conical structure having a shoulder for preventing slip out. The fixing pin 12 is preferably a synthetic resin such as Teflon(R) excellent in chemical resistance and a metal having durability against an electrode section inside liquid is also used and it is generally preferable to use plural pieces on the peripheral part of the electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electrolytic cell, for example,
The present invention relates to an electrolytic cell used for electrolysis of an aqueous solution of an alkali metal salt, water, or a fuel cell, particularly an electrolytic cell having an ion exchange membrane or the like as a diaphragm, and having an anode and a cathode in contact with both surfaces thereof.

[0002]

2. Description of the Related Art A solid electrolyte membrane such as an ion-exchange membrane is used as a diaphragm to partition an anode chamber and a cathode chamber. An alkali metal salt such as chloride is used by using an electrolytic cell having an anode and a cathode in each chamber. Sodium, a method of electrolyzing an aqueous solution such as potassium chloride and recovering chlorine and the like together with sodium hydroxide and potassium hydroxide, or a method of obtaining alkali hypochlorite and the like, a method of electrolyzing water to obtain hydrogen and oxygen, Further, as a fuel cell, a method of recovering energy and the like are known.

As such an electrolytic cell, there is an electrolytic cell having a structure in which a solid electrolyte membrane, for example, an ion exchange membrane is sandwiched between positive and negative electrodes.

[0004] In this type of electrolytic cell, the distance between the electrodes becomes substantially zero, so that the loss of electricity due to the electric resistance of the electrolytic solution is omitted, and thus it can be said that the structure is excellent.

[0005] However, since a solid electrolyte membrane such as an ion exchange membrane composed of an organic substance is generally sandwiched between electrodes made of metal, vibrations during operation of the electrolytic cell and mistakes during assembling of the electrolytic cell may cause a problem. The electrodes may damage the solid electrolyte membrane.

[0006] In a large-sized electrolytic cell used industrially, it is considerably difficult to arrange both the positive and negative electrodes in a flat and parallel manner.

[0007] Therefore, a structure in which one electrode is a flexible and flexible perforated plate, and the electrode is further pressed by a conductive and elastic mat-like material, and is softly pressed to the other electrode surface via the solid electrolyte membrane. And so on.

For example, according to Japanese Patent Publication No. 63-53272, an electrode-layer membrane assembly obtained by bonding a substance comprising electrocatalyst particles to the surface of an ion exchange membrane;
A relatively rigid coarse screen provided on one electrode layer side of the assembly and an elastically compressible mat provided on the other electrode layer side of the assembly and having a volume of 1.5 times or more when compressed; , Between a cathode end plate having an inner rib or protrusion and an anode end plate having an inner rib or protrusion, wherein the elastic compression mat comprises a series of helical coils made of metal wire. A relatively rigid coarse screen provided as an electrode provided on one surface of an electrolytic cell and an ion exchange membrane of the alkali metal chloride aqueous solution which is a woven fabric and used as one electrode of the ion exchange membrane and the other of the ion exchange membrane A flexible or flexible thin screen provided on the surface and used as the other electrode, and 1.5 times as large as the compressed screen provided on the outer surface of the thin screen An elastically compressible mat having the above volume between a cathode end plate having ribs or protrusions on the inside and an anode end plate having ribs or protrusions on the inside. An electrolytic bath of an alkali metal chloride aqueous solution, which is a fabric of a series of helical coils made of metal wires, has been proposed. As an electrolytic cell with improved practicality,
No. 434 discloses a structure in which an anode compartment and a cathode compartment are separated by a cation exchange membrane, the anode compartment has an anode, and the cathode compartment has a cathode. Among the anode and the cathode, At least one electrode has a thickness of 0.3 mm or less, and the area of one hole is 0.05 mm ^{2 to} 1.0 mm.
² , a porous electrode surface having a large number of holes and a porosity of 20% or more is lined with a current collector having a porosity of 30% or more made of an aggregate of wires having a diameter of 0.1 to 1 mm. An electrolytic cell for alkali metal salt electrolysis using an ion exchange membrane method has been proposed.

[0009]

As described above, a common structure in an electrolytic cell having a structure in which a solid electrolyte membrane is sandwiched between positive and negative electrodes is that at least one electrode is a flexible and flexible porous plate. An elastic current collector, generally a mat-like material, is arranged in a compressed state on the back side thereof, and the resilience of the current collector keeps the electric conductivity between the electrode and the elastic mat by pressing the solid electrolyte membrane. The position where the electrolyte membrane and / or the elastic mat is present is kept unchanged.

[0010] In the case of a large electrolytic cell, when assembling an electrolytic cell body which is a heavy load, a solid electrolyte membrane such as an ion exchange membrane, a flexible electrode and an elastic mat are superposed and sandwiched between electrode chambers. This is not easy, and often results in misalignment, requiring reassembly. Also, during the operation of the electrolytic cell, the solid electrolyte membrane is strongly sandwiched and fixed at the periphery of the electrolytic cell and the like, but the flexible electrode and the elastic mat are simply fixed by pressure by the elastic force of the elastic mat. For this reason, the position may have been shifted due to vibrations or the like based on internal pressure fluctuations during the operation of the electrolytic cell.

A method of partially fixing the elastic mat or the flexible electrode to the electrolytic cell frame, particularly the back wall or the current-collecting porous body fixed to the back wall by welding or the like is also conceivable. There is a problem that much trouble is required to attach and detach the fixed portion when repairing the elastic mat.

The inventors of the present invention have made various studies based on a novel idea that the flexible electrode and / or the elastic mat are detachably fixed, and have completed the present invention.

[0013]

SUMMARY OF THE INVENTION The present invention provides a solid electrolyte membrane electrolytic cell comprising one of a fixed rigid electrode (A) and the other of a removable flexible electrode (B). , (B) the electrode is pressed against the electrode (A) together with the solid electrolyte membrane by an elastic mat existing between the electrode and the porous current collector plate. (B) an electrolytic cell characterized by being fixed from the contact surface side with the solid electrolyte membrane through the electrode (B) and the elastic mat, with a pin engaged with a hole of the porous current collector plate. is there.

Further, the present invention relates to a fixing pin used in the electrolytic cell, wherein the pin has an enlarged head and forms a shoulder portion for preventing withdrawal through a neck portion. The present invention proposes a pin having a tip portion.

That is, one of the features of the present invention resides in an electrolytic cell in which a flexible electrode and / or an elastic mat are detachably fixed to a porous current collector plate on the back surface of the elastic mat using a plurality of pins. The other is in the fixing pin used for it.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. For convenience of explanation, the electrolytic cell of the present invention will be described by way of example of electrolysis of an aqueous solution of an alkali metal halide, for example, sodium chloride. .

FIG. 1 is a conceptual diagram for explaining the electrolytic cell of the present invention. Reference numeral 1 denotes an anode chamber frame, and reference numeral 2 denotes a rear wall of the anode chamber. Reference numeral 3 denotes an anode conductive rib, and reference numeral 4 denotes an anode. In the electrolysis of an aqueous solution of an alkali metal halide salt, for example, the electrolysis of sodium chloride, chlorine is generated at the anode. Therefore, the anode is usually made of a chlorine-resistant material such as titanium, or the inside of the anode chamber is lined. The anode rib and the anode are also made of titanium. The anode is a relatively rigid perforated plate, for example, expanded metal, a metal mesh composed of thick metal wires with punched metal rigidity, a metal rod connected in a grid, etc., and the size of one hole is 2 to 2. 100 mm ² , preferably ^{2 to 30} mm ²
There are many holes. The aperture ratio is a perforated plate having a pore ratio of 20% or more. The anode is coated with an anode active material such as a mixture of a white metal oxide or a platinum group metal oxide with a Group 4 to Group 8 metal oxide of the Synchronous Table. 5 is a cation exchange membrane. Usually, it has a perfluoroalkyl ether such as Nafion (trade name) as a skeleton and has an ion exchange group such as a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, or a mixed group thereof. Reference numeral 6 denotes a flexible and flexible cathode, which is usually a perforated plate of mild steel or nickel, that is, a punched metal or mesh (wire mesh). In some cases, as a cathode active material, for example, sulfur-containing nickel plating or nickel Alloy plating with a Group 6 or Group 8 metal (excluding nickel) of the periodic table is applied. Reference numeral 7 denotes an elastic mat, which is an aggregate of mild steel or nickel wires, particularly a structure in which coiled materials are entangled with each other, a woven fabric (or knitted fabric) subjected to crimping, and further subjected to helibone processing to impart elasticity. It is a mat-like material. Usually, with the cell assembled, the elastic mat is compressed to a volume of 30-70%, thereby serving to press the ion exchange membrane and the flexible cathode against the anode. The pressure at this time is generally 200 g / cm ² or less,
Preferably, it is about 30 to 50 g / cm ² . Reference numeral 8 denotes a cathode current collector, which is generally a rigid perforated plate, for example, an expanded metal, a punched metal, a woven metal wire or a metal rod having rigid bars arranged in parallel at appropriate intervals. Reference numeral 9 denotes a cathode rib, and a rear partition 11 of the cathode chamber frame 10.
And the cathode current collector is mechanically fixed.

In the above description, the anode is a rigid electrode and the cathode is a flexible electrode. However, a structure in which the cathode and the anode are reversed may be used.

As described above, in the electrolytic cell of the present invention, as shown in FIG. 2, the flexible cathode 6 is present on the front surface of the cathode chamber frame 10, and the elastic mat is present behind the cathode (FIG. 2). Not shown). The flexible cathode and the elastic mat penetrate from the front surface (the side in contact with the solid electrolyte membrane, that is, the ion exchange membrane) and are fixed by fixing pins 12. FIG. 3 is a conceptual side view showing that the fixing pin 12 penetrates the flexible cathode 6 and the elastic mat 7 and is engaged with the hole of the cathode current collector plate to fix the flexible cathode and the elastic mat. . The fixing pin has a function of expanding the head and holding down the flexible cathode, and has a shoulder for preventing withdrawal that can be engaged with the hole of the porous cathode current collector through the neck. The shape is not particularly limited as long as it has a substantially conical tip portion, but a shape as shown in FIG. 4 is generally preferable. 4A is a perspective view of a general fixing pin, and FIG. 4B is a side view thereof. (C) is a side view showing another example of the fixing pin.

Referring to FIG. 4A, the fixing pin will be further described. A is an enlarged head, and plays a role of holding down a wire mesh or the like constituting a flexible cathode by the enlarged portion. B is a neck, which is a portion penetrating the flexible cathode and the elastic mat as shown in FIG. C is a tip portion, and has a conical shape with a thin tip so that the flexible cathode and the elastic mat can be easily penetrated when the fixing pin is pierced.
Although FIG. 4A shows a conical shape, a pyramid can also be used. The tip has a shoulder near the joint with the neck for preventing the tip from coming off. This shoulder locks the edge of the hole of the porous cathode current collector plate. Therefore, the diameter (in the case of a circle) of the shoulder of the fixing pin is preferably such that it fits exactly into the hole of the cathode current collector. In particular, when the fixing pin is made of synthetic resin such as Teflon, it is slightly larger than the hole diameter, so that it is slightly deformed by the flexibility of the resin and easily penetrates the hole of the cathode current collector, and then has a shape. As a result, the shoulder portion engages with the edge of the hole on the back surface of the current collector plate to serve as a stopper. However, it is possible to pull out with larger force such as human power.

FIG. 4 (c) shows a structure in which a notch is formed at the tip, and when the tip is inserted, the tip is depressed, the diameter of the shoulder becomes small, and the tip is restored after passing through the hole of the cathode current collector plate. The shoulder acts as a stopper. Therefore, in the case of this shape, it is preferable to adopt it for a metal fixing pin or the like.

The material of the fixing pin must be able to withstand the liquid used in the electrode chamber. Generally, a synthetic resin having high chemical resistance such as Teflon is preferable, but a durable metal may be used according to the liquid in the electrode chamber.

The fixing pins are used for fixing the flexible electrode and / or the elastic mat to the current collector plate on the back surface, as is apparent from the purpose, so that a plurality of fixing pins are used according to the purpose. However, the position and number of pins fixed by the pins may be determined as appropriate. In general, it is often preferable to use it around the electrode.

Hereinafter, the present invention will be specifically described with reference to comparative examples.

[0025]

Comparative Examples and Examples Comparative Example 1 An aqueous sodium chloride solution was electrolyzed using an electrolytic cell having an electrode chamber having the structure shown in FIG. The hollow part of the chamber frame serving as the current-carrying part was 116 cm in length and 238 cm in width, and the thickness of the electrode chamber was 4.4 cm. The anode used is 1 thick
A punched metal made of titanium having a thickness of mm and coated with an active material was used. For flexible cathode, wire diameter 0.15m
m, an opening ratio of 68%, and a nickel-plated Ni ₃ Sn ₂ alloy having a hole area of 0.49 mm ² were used. Nickel wire diameter 0.08 mm, number of elastic mats
Two knitted knitted metal nets were stacked and crimped and used at a height of about 9 mm. As the current collector plate, expanded metal 1t × 4.5 _SW × 10 _LW × 1.2 _ST was used.
The method of fixing the flexible cathode and the elastic mat to the current collector plate was spot welding, and the four and upper sides were fixed at 11 places in the middle at equal intervals, one place at the center on both sides, and three places at the lower side at equal intervals. As the ion exchange membrane, Nafion N-962 (manufactured by DuPont) was used.

After operating for about 4 years in the electrolytic cell having the above structure, when the electrolytic cell was disassembled to replace the elastic mat, the ion exchange membrane was scraped at a part where spot welding was removed. . Also, when removing the flexible cathode, the weld is damaged,
Could not be reused.

Comparative Example 2 The structure of the electrolytic cell was the same as that of Comparative Example 1, except that the flexible cathode and the elastic mat were fixed to the current collector with a Ni wire having a wire diameter of 0.2 mm. As compared with Comparative Example 1, the mounting required a longer time to process and fix the Ni wire tip, and the electrolyzer had to be stopped for a long period of time. The operation was started with the electrolytic cell having the above structure, but a hole was opened in the ion exchange membrane at the tip of the Ni wire, and the electrolytic cell was stopped.

Example 1 The structure of the electrolytic cell was the same as that of Comparative Example 1, but the method of fixing the flexible cathode and the elastic mat to the current collector was performed using a Teflon pin having the shape shown in FIG. Part diameter 8mm, thickness 1mm,
The diameter of the neck is 2mm, the diameter of the shoulder to prevent withdrawal is 2.4mm,
A total length of 8 mm was used. The time for fixing the flexible cathode and the elastic mat to the current collector plate was the same as in Comparative Example 1, and the workability was easy because no instrument was used. After operating for about 4 years in the electrolytic cell with the above structure, the electrolytic cell was dismantled. There was no detachment of the pin at the time of dismantling, and the detachment of the pin was easy even when removing the flexible cathode, without damaging the flexible cathode. I was able to remove it.

[0029]

According to the present invention, not only the assembling and disassembling operations are particularly easy in a large electrolytic cell, but also
It is possible to prevent the displacement of the electrode and the elastic mat during the operation of the electrolytic cell, and the damage and deterioration of the solid electrolyte membrane, for example, the ion exchange membrane caused thereby.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of the electrolytic cell of the present invention.

FIG. 2 is a conceptual diagram of an electrode chamber showing an embodiment using the fixing pin of the present invention.

FIG. 3 is an explanatory view using a fixing pin of the present invention.

FIG. 4 is a view showing an example of a fixing pin of the present invention.

[Explanation of symbols]

 1 is an anode compartment frame 2 is a back partition 4 is an anode 5 is a cation exchange membrane 6 is a flexible cathode 7 is an elastic mat 8 is a cathode current collector 10 is a back wall 11 is a cathode compartment frame

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K021 AA03 AB01 AB07 BA03 CA02 DB13 DB31 DB50 DB53 EA03 EA05

Claims (2)

[Claims] 1. One of the electrodes is a fixed rigid electrode (A),
The other is a solid electrolyte membrane electrolytic cell comprising a removable flexible electrode (B). The electrode (B) is formed together with the solid electrolyte membrane by an elastic mat between the porous current collector and the solid electrolyte membrane (A). A structure pressed against the electrode, wherein the (B) electrode and the elastic mat penetrate the (B) electrode and the elastic mat from the contact surface side of the (B) electrode with the solid electrolyte membrane;
An electrolytic cell characterized in that the electrolytic cell is fixed with a pin that engages with a hole of a porous current collector plate. 2. The flexible, flexible body according to claim 1, wherein the head has an enlarged shape, and has a substantially conical tip forming a shoulder for preventing withdrawal through the neck. Electrode (B)
Fixing pin