JP2013108150A - Zero-gap electrolytic cell and method for manufacturing the same - Google Patents

Abstract

An anode, an ion exchange membrane, and a flexible cathode are arranged in close contact with each other, and a cushion mat and a porous current collector are sequentially provided on the back side of the flexible cathode. In the zero gap electrolytic cell, the interface concentration between the flexible cathode and the ion exchange membrane can be kept uniform and appropriate. Moreover, the method of manufacturing such a zero gap electrolytic cell at low cost is provided.
A zero-gap electrolytic cell having the above-described configuration, which includes a non-perforated plate 10 between a porous current collector 7 and a cushion mat 6, and the cushion mat 6 is formed of a metal coil body. The coil body is disposed so that the expansion / contraction direction of the coil body coincides with the vertical direction of the electrolytic cell, and 12 between the non-perforated plate 10 and the upper flange of the electrolytic cell, and the non-perforated plate and the lower flange of the electrolytic cell. Zero gap electrolyzers each having a gap between 13 and.
[Selection] Figure 4

Description

The present invention relates to an ion exchange membrane method electrolytic cell (hereinafter referred to as “zero gap electrolytic cell”) having a configuration in which an anode, an ion exchange membrane and a cathode are in close contact with each other, which is used in the electrolytic industry represented by chloralkali electrolysis.
More specifically, the anode, the ion exchange membrane, and the flexible cathode are closely arranged, and a cushion mat and a porous current collector are sequentially provided on the back side of the flexible cathode toward the outside. The present invention relates to a zero gap electrolytic cell having a novel structure excellent in the ability to supply an electrolytic solution to the interface between a cathode and an ion exchange membrane.

  Furthermore, the present invention is a novel method for manufacturing a zero gap electrolytic cell by remodeling an ion exchange membrane method electrolytic cell (hereinafter referred to as a “narrow gap electrolytic cell”) having a certain distance between a cathode and an ion exchange membrane. The present invention relates to a manufacturing method. According to this manufacturing method, it is possible to manufacture a zero gap electrolyzer that can use the ion exchange membrane stably for a long period of time at a very low cost with a very low power unit.

The ion exchange membrane method electrolytic industry represented by chloralkali electrolysis plays an important role as a raw material industry. In the electrolytic industry, an ion exchange membrane method electrolytic cell is the center of technology.
The ion exchange membrane method salt electrolysis, which is a representative example of the ion exchange membrane method electrolysis industry, is initially based on a narrow gap electrolytic cell having a constant interval, usually 1 to 3 mm, between the electrode and the ion exchange membrane. It was mainstream. In general, in salt exchange electrolysis using an ion exchange membrane method, the pressure in the cathode chamber is controlled higher than that in the anode chamber, and the ion exchange membrane is pressed against the anode. Are provided with a certain interval.

  A narrow gap electrolytic cell having a configuration in which a certain distance is provided between the ion exchange membrane and the cathode does not apply excessive force from the cathode to the ion exchange membrane, and the catholyte is uniform in the ion exchange membrane. Therefore, there is an advantage that the ion exchange membrane can be used stably for a long period of time. On the other hand, the narrow gap electrolytic cell has a drawback that a voltage loss due to electric resistance occurs between the ion exchange membrane and the cathode, and in principle the power unit is high.

  In order to overcome the above disadvantages of the narrow gap electrolytic cell, a so-called zero gap electrolytic cell in which the distance between the ion exchange membrane and the cathode is zero has been proposed. The zero gap electrolytic cell has the characteristics that the electric resistance between the ion exchange membrane and the cathode is as small as possible, and in principle, the electric power consumption is low. However, since the anode, the ion exchange membrane, and the cathode are in close contact with each other, if an excessive force is applied from the electrode, physical damage is likely to occur in the ion exchange membrane, and the electrolyte solution is present at the interface between the electrode and the ion exchange membrane. Has a problem that it is difficult to supply.

  In order to solve the above-mentioned problems of the zero gap electrolytic cell, zero gap electrolytic cells having various structures have been proposed. With reference to FIG. 1 showing a cross-sectional structure of a typical example of a conventional zero gap electrolytic cell, a proposal regarding a zero gap electrolytic cell is outlined below.

  For example, as shown in FIG. 1, the anode (4) made of a mesh screen having relatively high rigidity, the ion exchange membrane (3), and the anode (4) of the ion exchange membrane (3) are provided on the opposite surfaces. A cathode (5) made of a flexible or flexible thin screen, an elastic mat (cushion mat) (6) provided on the outer surface of the cathode (5), and the cushion mat (6) There has been proposed a zero gap electrolyzer (1) composed of a porous current collector (7) comprising a mesh screen having a relatively high rigidity provided on the outside (see, for example, Patent Document 1).

  As shown in FIG. 1, the zero gap electrolyzer described in Patent Document 1 has a flexible cathode (5) that is elastically repelled by a cushion mat (6) installed on the back surface of the flexible cathode (5). It has a structure that is pressed against the ion exchange membrane (3) toward the rigid anode (4). On the outside of the cushion mat (6), a porous current collector (7) comprising a mesh screen having relatively high rigidity is installed.

  In the zero gap electrolyzer (1) described in Patent Document 1, it is possible to press the rigid anode (4) and / or the flexible cathode (5) uniformly against the ion exchange membrane (3) with an appropriate pressure. It is. Therefore, in an industrial size zero gap electrolyzer having an electrolysis area of several square meters, physical damage of the ion exchange membrane due to excessive force from the electrodes can be avoided.

Furthermore, a zero gap electrolytic cell with various improvements based on the zero gap electrolytic cell described in Patent Document 1 has been proposed.
As one improvement, the flexible cathode (5) has “a thickness of 0.3 mm or less, an area of one hole of 0.05 to 1.0 mm ² , and a large aperture ratio. 20% or more ", preferably, the cushion mat (6) is composed of" a collection of wires having a diameter of 0.1 to 1 mm ", and the porous current collector (7) is substantially the same as the rigid electrode (anode). A zero-gap electrolytic cell made of a perforated plate having a certain degree of rigidity is disclosed (for example, see Patent Document 2).

  As another improvement, the flexible cathode (5) and the cushion mat (6) pass through the flexible cathode (5) and the cushion mat (6) and engage with the hole of the porous current collector (7). A zero gap electrolyzer having a configuration fixed with a mating pin (12) is disclosed (see, for example, Patent Document 3).

  Disclosed is a technique for accelerating the supply of electrolyte to the interface between the anode (4) and the ion exchange membrane (3) using an anode having a height difference of 5-50 μm on the anode surface in a zero gap electrolytic cell. (For example, see Patent Document 4). Patent Document 4 further discloses that when an internal circulation duct is installed in the polar chamber, the supply of the electrolyte solution to the interface between the electrode and the ion exchange membrane is further promoted.

  The cushion mat (6) provided in the electrolytic cell described in Patent Document 4 is composed of “a cushion mat having a thickness of 3 to 15 mm obtained by corrugating a wire made of nickel having a wire diameter of about 0.1 mm”. In addition, it is described that the porous current collector (7) is preferably composed of “expanded metal or punched plate through which gas generated from the cathode passes without difficulty to the partition wall”. Further, Patent Document 4 discloses that as the porous current collector (7), it is possible to "use the cathode used in the conventional narrow gap cell as it is".

  In the conventional zero-gap electrolytic cell as described above, the gas generated from the cathode must pass through the cushion mat and the porous current collector and pass through the partition wall without any problem. It has been common general technical knowledge to use a porous current collector (7) made of expanded metal or a punched plate as the electric body.

  In a zero gap electrolytic cell, it is known that one of the problems is to keep the cathode side interface concentration of the ion exchange membrane appropriate. For example, Non-Patent Document 1 states that “consideration is the interface concentration between the cathode side and the anode side of the membrane. Since the cathode on which the water reduction reaction occurs is in contact with the membrane, the alkali concentration is locally The increase in alkali concentration at the interface of the film deteriorates the resistance to impurities, causes damage to the carboxylic acid layer, and decreases the electrolytic performance.

  FIG. 2 shows an enlarged cross section of part A of the zero gap electrolytic cell shown in FIG. 1, and FIG. 3 shows the flow of hydrogen gas and electrolyte generated in the flexible cathode (5) in part A of FIG. Is illustrated with an arrow. As described above, in the conventional zero gap electrolytic cell, the hydrogen gas generated in the flexible cathode (5) passes through the cushion mat (6) and the porous current collector (7), and the partition wall (11). It moves to the side and rises with the electrolyte between the porous current collector (7) and the partition wall. Therefore, the fluidity of the electrolyte solution between the ion exchange membrane (3) and the porous current collector (7) is poor, and it is difficult to keep the cathode side interface concentration of the ion exchange membrane appropriate.

An internal circulation duct is installed between the porous current collector (7) and the partition wall (11) to cause internal self-circulation between the porous current collector (7) and the partition wall (11). However, the flow state of the electrolyte solution between the porous current collector (7) and the partition wall (11) is hardly improved.
As described above, in the conventional zero gap electrolytic cell, it is still difficult to keep the interface concentration between the flexible cathode (5) and the ion exchange membrane (3) uniform and appropriate. The fault that it cannot be used stably for a period remained.

Japanese Examined Patent Publication No. 63-53272 JP 59-173281 A JP 2000-178781 A International Publication No. 2004/048643 Pamphlet

The 29th Electrolysis Technology Conference-Soda Industry Technology Conference-Abstracts of Lectures, Electrochemical Society of Electrochemical Science and Technology Committee, p65-68

  An object of the present invention is to provide a zero gap electrolytic cell capable of maintaining a uniform and appropriate interface concentration between the flexible cathode (5) and the ion exchange membrane (3), and such a zero gap. It is providing the manufacturing method which manufactures an electrolytic cell at low cost.

In the present invention, as illustrated in FIG. 4, the anode (4), the ion exchange membrane (3), and the flexible cathode (5) are closely arranged, and the back side of the flexible cathode (5). In a zero gap electrolytic cell having a structure in which a cushion mat (6) and a porous current collector (7) are sequentially provided outward, the porous current collector (7) and the cushion mat (6) There is a non-perforated plate (10) in between, the cushion mat (7) is made of a metal coil body, and the coil body is arranged so that the expansion and contraction direction of the coil body coincides with the vertical direction of the electrolytic cell. Provided is a zero-gap electrolytic cell having gaps (12) and (13) between a perforated plate and an upper flange of the electrolytic cell and between a non-porous plate and a lower flange of the electrolytic cell, respectively. .
The cushion mat (7) is preferably composed of a plurality of metal coil bodies, and the plurality of metal coil bodies are arranged in parallel to each other.

  The present invention further provides a method for producing a zero gap cell from a narrow gap cell. In this manufacturing method, the cathode used in the narrow gap electrolytic cell is used as a porous current collector (7) shown in FIG. 4, and a non-porous plate (10) is installed thereon, A gap (12) (13) is formed between the plate (10) and the upper flange of the electrolytic cell, and between the non-porous plate and the lower flange of the electrolytic cell. Next, a cushion mat (6) made of a metal coil body is placed on the non-perforated plate (10) so that the expansion / contraction direction of the coil coincides with the vertical direction of the electrolytic cell. Preferably, using a cushion mat (6) made of a plurality of metal coil bodies, the plurality of metal coil bodies are installed in parallel to each other. Next, the flexible cathode (5) is placed on the cushion mat (6), and the flexible cathode (5) and the ion exchange membrane (3) are further utilized by utilizing the elastic repulsive force of the cushion mat (6). Close contact with the anode (4).

The narrow gap electrolytic cell provided by the present invention is excellent in the fluidity of the electrolyte solution between the ion exchange membrane (3) and the non-porous plate (10), and has a flexible cathode (5) and an ion exchange membrane (3). Therefore, the interface concentration between the flexible cathode (5) and the ion exchange membrane (3) is kept uniform and appropriate. As a result, the ion exchange membrane can be stably used for a long period of time with a low power intensity.
Moreover, according to the manufacturing method of the zero gap electrolytic cell which this invention provides, the zero gap electrolytic cell which has the said characteristic can be manufactured simply and cheaply from the existing narrow gap electrolytic cell.

It is a figure which shows an example of the cross-sectional structure of the conventional zero gap electrolytic cell. It is the figure which expanded the A section shown in FIG. It is a figure which shows the flow of the gas of A section shown in FIG. 1, and electrolyte solution. It is a figure which shows an example of the cross-section of the zero gap electrolytic cell of this invention. It is the figure which expanded the B section shown in FIG. It is a figure which shows the flow of the gas and electrolyte solution in the structure shown in FIG. It is a figure which shows an example of the preferable cushion used by this invention. It is a figure which shows an example of the state which attached the cushion to the flexible electrode. It is sectional drawing of the a part shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the following description, the case where the present invention is used for salt electrolysis will be described as an example, but it is needless to say that the present invention can be suitably used for other than salt electrolysis, for example, potassium chloride aqueous solution electrolysis and alkaline water electrolysis.
An example of the zero gap electrolytic cell of the present invention is shown in FIG.

The anode chamber (1), the anode (4), and the ion exchange membrane (3) are not limited at all and may be appropriately selected from known ones.
Moreover, there is no restriction | limiting in the basic structure of a cathode chamber (2), A well-known structure is applicable. For example, an internal circulation duct may exist or may not exist in the cathode chamber.
In addition, it is not necessary to provide a gas-liquid separation chamber in the upper part, but it is preferable to install a gas-liquid separation chamber because electrolysis can be performed more stably at a high current density. What is necessary is just to select a gas-liquid separation chamber suitably from what was proposed conventionally.

  The flexible cathode (5) used in the present invention may be the same as that used in the conventional zero gap electrolytic cell. For example, the step width is 0.1 mm to 1.0 mm, the minor axis is 0.5 mm to 5.0 mm, the major axis is 1.0 mm to 10 mm, the plate thickness is 0.1 mm to 1.0 mm, and the opening Examples thereof include a noble metal electrode catalyst such as platinum alloy or ruthenium oxide supported on an expanded metal having a rate of 48 to 60%. Various hydrogen generating electrodes on which noble metal electrocatalysts such as platinum alloys and ruthenium oxides are supported have been proposed, and any of them can be suitably used.

  The porous current collector (7) has good conductivity and excellent corrosion resistance and does not have to be deformed by the reaction force of the cushion mat (6), and is the same as that used in conventional zero gap electrolyzers. Stainless steel expanded metal or punched perforated plates can be used. The porous current collector (7) may be a diverted cathode of a conventional narrow gap electrolytic cell as it is, and those detailed structures include those known to those skilled in the art.

In the zero gap electrolytic cell of the present invention, it is essential to install the non-porous plate (10) on the surface of the porous current collector (7) on the ion exchange membrane side. The effect of the present invention cannot be obtained without the non-perforated plate (10). It is essential that the non-porous plate (10) is corrosion resistant and excellent in electrical conductivity, and a flat plate such as nickel or stainless steel can be suitably used.
Although there is no limitation in particular in the thickness of a non-porous board (10), it is 0.1-2 mm normally, Preferably, it is 0.5-1 mm. If it is too thin, handling becomes difficult, and if it is too thick, the cost increases.

  As the non-porous plate (10), a flat plate that is not a porous plate such as a punched metal, an expanded metal, or a net is used. That is, it is a flat plate without a hole. However, it is important that the non-perforated plate (10) does not substantially pass hydrogen gas. For example, when pinning the cushion mat (6) or the flexible cathode (5), the non-perforated plate (10) ) May be a flat plate having a hole opened for the purpose of inserting the pin.

  The cushion mat (6) used by this invention is comprised from a metal coil body. In the cushion mat (6), it is essential that the expansion and contraction direction of the coil is directed in the vertical direction of the electrolytic cell. A preferred cushion mat (6) is composed of a plurality of metal coil bodies, which are arranged in parallel to each other, and installed such that the expansion / contraction direction of the coils coincides with the vertical direction of the electrolytic cell.

When the cushion mat (6) is made of, for example, a wire aggregate or a wire woven wire, the rise that occurs between the flexible cathode (5) and the non-perforated plate (10) The flow is limited, and the effects of the present invention cannot be sufficiently obtained.
For the same reason, the effects of the present invention cannot be sufficiently obtained when the metal coil bodies (8) are orthogonal to each other or when the expansion / contraction direction of the coil is directed in the horizontal direction of the electrolytic cell.

  FIG. 7 shows an example of a preferred cushion mat (6) used in the present invention. The cushion mat (6) is configured by winding a plurality of metal coil bodies (8) around a metal frame (9), and is described in, for example, Japanese Patent Application Laid-Open No. 2004-300547. In this cushion mat (6), a plurality of metal coil bodies (8) are arranged in parallel, and the expansion and contraction direction of the metal coil body (8) is easily and reliably made to coincide with the vertical direction of the electrolytic cell. It can be done.

  As the material of the metal frame (9), a material having high corrosion resistance such as nickel or stainless steel is preferably used, and the diameter of the frame is preferably 1 to 3 mm, more preferably 1 to 2 mm. If the diameter of the frame is too small, the strength will be insufficient and handling will be difficult. Conversely, if it is too thick, the material cost will deteriorate, and the frame will be excessively pushed against the ion exchange membrane (3) and flexible cathode (5). The ion exchange membrane (3) and the flexible cathode (5) may be damaged.

  As shown in FIG. 8, when the coil mat (14) is formed by winding the metal coil body (8) around the metal frame (9), the number of windings of the metal coil body (8) is 3 to 9 times / cm. Is preferable, and more preferably 6 to 7 times / cm. If the number of coil turns is too small, the reaction force is insufficient, or the coil collapses during compression and the elasticity is insufficient. On the contrary, if the number of windings is too large, the reaction force may be excessive or the handling property may be deteriorated.

As a material of the metal coil body (8), a material having high corrosion resistance and high electrical conductivity such as nickel or stainless steel is preferably used. Moreover, the thing which coat | covered nickel with the surface of the coil body excellent in electroconductivity, such as copper, and improved corrosion resistance is used suitably.
The ring diameter (apparent diameter of the coil) of the metal coil body (8) is not particularly limited, but is usually 3 to 10 mm. If the ring diameter is too small, the compressible thickness of the elastic mat is insufficient, and the effects of the present invention may not be exhibited. On the other hand, if the ring diameter is too large, the handleability may be deteriorated, and the elastic repulsion may be insufficient due to plastic deformation during compression.

In the zero gap electrolytic cell of the present invention, as shown in FIG. 4, a gap (12) is formed between the non-perforated plate (10) and the upper flange of the electrolytic cell, particularly the upper flange of the cathode chamber (2). It is essential. If there is no gap (12) between the non-perforated plate (10) and the upper flange of the electrolytic cell, the hydrogen gas generated in the flexible cathode (5) cannot be discharged smoothly, so that the effect of the present invention is obtained. Absent.
The size of the gap (12) between the non-perforated plate (10) and the upper flange of the electrolytic cell is not limited as long as hydrogen gas and the electrolyte flow smoothly. Usually, the size of the gap (12) is 5 to 150 mm, preferably 30 to 100 mm. If this gap (12) is too narrow, the flow of hydrogen gas and the electrolyte is hindered. If it is too wide, excess hydrogen gas is mixed into the partition walls, resulting in insufficient internal circulation.

  In the electrolytic cell of the present invention, as shown in FIG. 4, a gap (13) is formed between the non-porous plate (10) and the lower flange of the electrolytic cell, particularly the lower flange of the cathode chamber (2). It is essential. If there is no gap (13) between the non-perforated plate (10) and the lower flange of the electrolytic cell, the electrolyte supply to the space formed by the flexible cathode (5) and the non-perforated plate (10) is hindered. Therefore, the effect of the present invention cannot be obtained.

  The size of the gap (13) between the non-perforated plate (10) and the lower flange of the electrolytic cell is not limited as long as hydrogen gas and the electrolyte flow smoothly. Usually, the size of the gap (13) is 5 to 200 mm, preferably 30 to 150 mm. If this gap (13) is too narrow, the flow of the electrolytic solution is hindered. If it is too wide, excessive hydrogen gas is mixed into the partition walls, resulting in insufficient internal circulation.

There may or may not be a gap between the non-perforated plate (10) and the left and right flanges of the cathode chamber (2). There are gaps between the porous current collector (7) and the upper, lower, left and right flanges of the cathode chamber (2), and between the cushion mat (6) and the upper, lower, left and right flanges of the cathode chamber (2). It does not have to be.
Moreover, it is preferable that a cushion mat (6) and a porous electrical power collector (7) are the same size as a non-porous board (10), or more than equivalent. When the cushion mat (6) and / or the porous current collector (7) is smaller than the non-porous plate (10), the contact between the flexible cathode (5) and the ion exchange membrane (3) becomes uneven, The effect of the present invention may not be obtained.

  The flexible cathode (5) used in the present invention is widely known as a hydrogen generating electrode that generates hydrogen during electrolysis as a cathode for salt electrolysis, and usually has a nickel base carrying a hydrogen generating electrode catalyst. A so-called active cathode is applied. Currently, various active cathodes have been developed and put to practical use, and any of these active cathodes can be used in the present invention. As described above, noble metal electrode catalysts such as platinum alloys and ruthenium oxides are supported. A hydrogen generating electrode (for example, JP-A-2005-330575) is preferable.

  The metal substrate of the flexible cathode (5) has a step width of 0.1 mm to 1 mm, a minor axis of 0.5 mm to 5.0 mm, a major axis of 1.0 mm to 10 mm, and a plate thickness of 0.1 mm or more. An expanded metal type mesh having an opening ratio of 48 to 60% is preferably 1.0 mm or less. If the metal substrate has a shape or size that deviates from these ranges, the rigidity of the flexible cathode (5) will be excessively high, and there will be a part where the pressure applied to the ion exchange membrane will partially increase. In some cases, the degree of damage to the ion exchange membrane (3) is large and the frequency of damage increases.

The flexible cathode (5) preferably has an area of one hole of 1.0 to 10 mm ² and an aperture ratio of 48 to 60%. If the area and / or opening ratio of one hole deviates from these ranges, the gas detachability from the flexible electrode (5) may deteriorate, or the strength of the flexible electrode (5) may be insufficient. Such a problem may occur.

  The zero gap electrolyzer of the present invention having the structure described above exhibits the actions and effects described below. That is, as shown in FIG. 5 in which the portion B shown in FIG. 4 is enlarged, since the non-porous plate (10) is installed, the hydrogen gas generated at the cathode passes through the porous current collector (7). It rises between the flexible cathode (5) and the non-perforated plate (10) without coming out to the partition (11) side. In the zero gap electrolytic cell of the present invention, the cushion mat is formed of a metal coil body (8), and the cushion mat has a metal coil body (8) whose coil expansion / contraction direction coincides with the vertical direction of the electrolytic cell. . Therefore, there is no barrier when the hydrogen gas moves upward, and the increase of the hydrogen gas is not hindered.

  The raised hydrogen gas is discharged from the gap (12) between the non-perforated plate (10) and the upper flange at the upper part of the electrolytic cell. At the same time, the electrolyte between the flexible cathode (5) and the non-porous plate (10) rises due to the so-called gas lift effect, and hydrogen gas is released from the gap (12) between the non-porous plate (10) and the upper flange. It is discharged with.

  On the other hand, since the hydrogen gas generated in the flexible cathode (5) does not pass through the porous current collector (7) to the partition wall (11) side, the non-porous plate (10), the partition wall (11), The amount of gas between them is small, and the apparent specific gravity of the electrolytic solution is higher than the apparent specific gravity of the electrolytic solution between the flexible cathode (5) and the non-porous plate (10). Therefore, the electrolyte having a high apparent specific gravity between the non-porous plate (10) and the partition wall (11) descends and flows into the ion exchange membrane side from the gap (13) between the non-porous plate (10) and the lower flange. .

As a result, as shown in FIG. 6, an upward flow of the electrolytic solution is generated on the side of the ion exchange membrane (3), and a downward flow of the electrolytic solution is generated on the partition wall (11). In addition, internal self-circulation occurs throughout the cathode chamber. Therefore, the electrolyte can be sufficiently supplied to the interface between the ion exchange membrane (3) and the flexible cathode (5), which is impossible with the conventional zero gap electrolytic cell. It is possible to keep the electrolyte concentration at the interface of the flexible cathode (5) good.
The action / effect of the zero gap electrolytic cell of the present invention as described above is such that the hydrogen gas generated in the flexible cathode (5) passes through the porous current collector (7) and is extracted to the partition wall (11) side. It cannot be foreseen from conventional technical common sense.

There is no special limitation in the manufacturing method of the zero gap electrolytic cell of this invention demonstrated above. However, in general, the electrolytic cell is expensive, and even if the narrow gap electrolytic cell in use in the existing plant is discarded and replaced with a newly produced zero gap electrolytic cell of the present invention, power consumption is reduced and ion exchange is performed. Although the effect that the membrane can be used stably for a long period of time can be enjoyed, the total cost may not be satisfied due to an increase in fixed cost.
If the method of manufacturing the zero gap electrolyzer of the present invention described below, that is, the method of converting the narrow gap electrolyzer to the zero gap electrolyzer of the present invention is adopted, the increase in fixed cost is minimized. Thus, a further effect can be obtained.

The manufacturing method of the zero gap electrolytic cell according to the present invention is performed by modifying the narrow gap electrolytic cell. There is no particular limitation on the narrow gap electrolytic cell used in the present invention, but the effect of the present invention can be obtained more remarkably when a narrow gap electrolytic cell capable of performing a high current density operation of 4 kA / m ² or more before remodeling is used. . For this reason, the narrow gap electrolytic cell used for the modification is preferably a bipolar narrow gap electrolytic cell having a gas-liquid separation chamber in the anode chamber and the cathode chamber and having excellent electrolyte dispersibility in the anode chamber.
The anode chamber (1) of the narrow gap electrolytic cell does not need to be modified. However, if the anode performance has deteriorated before remodeling, or if the flange surface or the like is corroded, it goes without saying that necessary maintenance such as renewing the anode and repairing the corroded portion is performed.

Prior to remodeling, it is preferable to clean the cathode and the inside of the cathode chamber as necessary. The hydrogen generating catalyst coated on the cathode may be left as it is or may be removed. If there is a part where the adhesion of the hydrogen generating catalyst coated on the cathode to the base material is insufficient, it may fall off during operation after remodeling, adversely affecting caustic quality or damaging the ion exchange membrane Therefore, the cathode hydrogen generation catalyst is usually removed.
In this case also, it is not necessary to completely remove the cathode hydrogen generating catalyst, and only the portion having insufficient adhesion needs to be removed. For example, the cathode and the inside of the cathode chamber (2) may be washed with a 10% hydrochloric acid aqueous solution to clean the inside of the cathode chamber (2) and simultaneously dissolve and remove the catalyst on the cathode surface.

  The cathode is then used as the porous current collector (7) and a non-perforated plate (10) is attached to it. If the non-perforated plate (10) can be fixed to the porous current collector (7), the mounting method is not particularly limited. For example, a non-porous plate (10) may be superimposed on the porous current collector (7) and spot welded. At that time, as a welding preparatory work, the welded portion between the non-porous plate (10) and the porous current collector (7) is usually cleaned by mechanical polishing or the like.

  Between the non-perforated plate (10) and the upper flange of the cathode chamber (2), and between the non-perforated plate (10) and the lower flange of the cathode chamber (2), there are gaps (12, 13), respectively. However, the method is not particularly limited. For example, as described above, when the non-porous plate (10) is installed on the cathode (which becomes the porous current collector (7) of the zero gap electrolytic cell) used in the narrow gap electrolytic cell, A non-perforated plate (10) of a size may be prepared, positioned, and attached so as to create a gap (12, 13) (ie, installation of the non-perforated plate (10) and formation of the gap (12, 13)) And may be performed simultaneously). Alternatively, as another example, after attaching the non-porous plate (10) to the cathode of the narrow gap electrolytic cell as described above, a part of the non-porous plate (10) is cut to obtain a gap having a desired size ( 12, 13) may be formed. At this time, the porous current collector (7) is cut together with the non-porous plate (10), and between the old cathode (7) and the upper flange of the cathode chamber (2), and between the old cathode (7) and the lower flange. A gap (12, 13) may be provided between the two. In general, it is preferable to prepare a non-perforated plate (10) of an appropriate size, position it, and attach it so that there is a gap (12, 13).

Next, the cushion mat (6) composed of the metal coil body (8) is attached to the non-perforated plate (10) so that the expansion / contraction direction of the coil coincides with the vertical direction of the electrolytic cell. Preferably, using a cushion mat (6) made of a plurality of metal coil bodies, the plurality of metal coil bodies are installed in parallel to each other.
The method for attaching the cushion mat (6) is not particularly limited as long as the cushion mat (6) can be fixed to the non-porous plate (10). For example, the frame (9) and the non-perforated plate (10) of the cushion mat (6) in which the metal coil body (8) illustrated in FIG. 6 is wound around the frame (9) may be attached by spot welding.
You may carry out spot welding of these in a lump in the state which piled up the non-porous board (10) on the porous electrical power collector (7), and also piled up the cushion mat (6).

  Next, the flexible cathode (5) is installed on the cushion mat (6), but the installation method is not particularly limited as long as the flexible cathode (5) can be fixed. For example, as shown in FIGS. 8 and 9, holes are formed in the flexible cathode (5) and the non-perforated plate (10) in a place not penetrating the metal coil body (8) of the cushion mat. The fixing pin (15) may be passed through the hole and fixed with the fixing pin (15) engaged with the hole of the porous current collector (7). As the fixing pin (15), for example, the fixing pin described in Patent Document 3 is preferably used.

  Since the cushion mat (6) used in the present invention is fixed to the porous current collector (7) together with the non-porous plate (10), the fixing pin only has the flexible cathode (5) in the porous collector. The fixing pin (15) is preferably attached to a portion that does not penetrate the cushion mat (6) as long as it can be fixed to the electric body (7). When the fixing pin (15) is attached to a portion penetrating the cushion mat (6), the fixing pin (15) is pushed against the elastic repulsion force of the cushion mat (6) at the time of attachment. In some cases, the cathode (5) or the fixing pin (15) may be damaged, or the flexible cathode (5) may be wrinkled to physically damage the ion exchange membrane (3).

When the fixing pin (15) is attached to a portion that does not penetrate the cushion mat (6), the fixing pin (15) receives almost no elastic repulsive force of the cushion mat (6), and the attaching work is easy. (15) No trouble occurs in the flexible cathode (5) and the ion exchange membrane (3).
In addition, the fixing pin penetrates the hole opened in the non-perforated plate (10) in order to fix the flexible cathode (5) with the fixing pin, and leaks from the hole to the partition wall (11) side. The amount of hydrogen gas to be introduced is extremely small and does not hinder internal circulation.

  Next, the flexible cathode (5) and the ion exchange membrane (3) are brought into contact with each other using the elastic repulsion force of the cushion mat (6). When the flexible cathode (5) is brought into contact with the ion exchange membrane (3), the elastic repulsion of the cushion mat (6) does not mechanically damage the ion exchange membrane, and the flexible cathode (5 ) Is not particularly limited as long as it can be brought into uniform contact with the ion exchange membrane (3). Usually, the elastic repulsion force is 7 to 17 kPa as an average surface pressure.

When the elastic repulsive force is weak, the contact between the flexible cathode (5) and the ion exchange membrane (3) becomes insufficient, and the effect of reducing the power intensity is reduced. On the contrary, if the elastic repulsion is strong, the flexible cathode (5) is excessively pressed against the ion exchange membrane, and the ion exchange membrane is likely to be physically damaged.
The elastic repulsive force of the cushion mat (6) is obtained by measuring the relationship between the thickness of the cushion mat (6) and the elastic repulsive force in advance, and the thickness of the cushion mat (6) so that a desired elastic repulsive force can be obtained. Can be adjusted. The thickness of the cushion mat (6) can be easily adjusted, for example, by adjusting the thickness of the gasket.

  The ion exchange membrane electrolytic cell of the present invention has special features that reduce the problems of the conventional narrow gap electrolytic cell, the cost when replacing the cathode, and obtain the energy saving performance of the zero gap electrolytic cell. Therefore, the ion exchange membrane method electrolytic cell of the present invention can be widely used in the electrolysis industry typified by chloralkali electrolysis such as salt electrolysis, and the energy required for electrolysis in the electrolysis industry can be stably kept low for a long time. Can do.

1: Anode chamber 2: Cathode chamber 3: Ion exchange membrane 4: Anode 5: Flexible cathode 6: Cushion mat 7: Porous current collector 8: Metal coil body 9: Frame 10: Non-perforated plate 11: Partition wall 12: Gap between the non-perforated plate and the upper flange of the electrolytic cell 13: Gap between the non-perforated plate and the lower flange of the electrolytic cell 14: Coil mat 15: Pin for fixing

Claims (4)

  An ion exchange membrane method electrolytic cell, in which an anode, an ion exchange membrane, and a flexible cathode are arranged in close contact with each other, and a cushion mat and a porous current collector are provided outward on the back side of the flexible cathode. In a zero gap electrolytic cell having a structure provided sequentially, a non-porous plate is provided between a porous current collector and a cushion mat, and the cushion mat is formed of a metal coil body, and the expansion and contraction direction of the coil body is It is arranged so as to coincide with the vertical direction of the electrolytic cell, and has a gap between the non-porous plate and the upper flange of the electrolytic cell, and between the non-porous plate and the lower flange of the electrolytic cell. Zero gap electrolyzer characterized by   The zero gap electrolytic cell according to claim 1, wherein the cushion mat is composed of a plurality of metal coil bodies, and the plurality of metal coil bodies are arranged in parallel to each other. In a method of manufacturing a zero gap electrolytic cell from a narrow gap electrolytic cell,
A non-porous plate is installed on the cathode of the narrow gap electrolytic cell,
A gap is formed between the non-perforated plate and the upper flange of the electrolytic cell, and between the non-perforated plate and the lower flange of the electrolytic cell,
On the non-perforated plate, a cushion mat made of a metal coil body is installed so that the expansion / contraction direction of the coil matches the vertical direction of the electrolytic cell,
A method for producing a zero-gap electrolytic cell, wherein a flexible cathode is placed on a cushion mat, and then the flexible cathode, the ion exchange membrane, and the anode are brought into close contact with each other.   The zero gap electrolytic cell according to claim 3, wherein a cushion mat made of a plurality of metal coil bodies is installed on the non-perforated plate so that the plurality of metal coil bodies are parallel to each other.

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