Patent Description:
As an electrolyzer used for alkaline water electrolysis, pure water electrolysis, electrolysis of unpurified water, brine electrolysis, chloride aqueous solution electrolysis, bromide aqueous solution electrolysis, hydrochloric acid aqueous solution electrolysis, sulfuric acid aqueous solution electrolysis, and the like, an electrolyzer in which a separator is provided between an anode and a cathode, and the anode and cathode are isolated by the separator is often used. An electrolyte to be supplied in the electrolyzer, electrolytically generated gases, such as a hydrogen gas, an oxygen gas, a chlorine gas, and a halogen gas, which are generated by electrolysis, and the electrolyte in the electrolyzer must not leak from the edge part of the separator to the outside of the electrolyzer. If an electrolytically generated gas, an electrolyte, or the like leaks, continuous operation of the plant cannot be performed, and further, problems in terms of the operation manager and the environment may occur.

Conventionally, in the electrolyzer as described above, in order to prevent the leakage of an electrolyte, an electrolytically generated gas, or the like from the edge part of the separator for the electrolyzer, two thin-plate-like gaskets, or four or two O-rings are disposed between the anode and the cathode to prevent the leakage of an electrolytically generated gas, an electrolyte, or the like and sandwich the separator by these sealing elements.

In the electrolyzer as described above, for example, when four O-rings <NUM> shown in <FIG> are used, the separator is sandwiched by two O-rings <NUM> on the electrolyzer side, and the electrolyte is prevented from leaking outside the electrolyzer by two O-rings <NUM> on the outer periphery side of the electrolyzer. Note that when an ion exchange membrane is used as a separator, the ion exchange membrane is like a film, and there is no leakage due to oozing out of the liquid, which occurs in the case of using the separator, and therefore the electrolyzer is sealed with only two O-rings.

Further, in the electrolyzer as described above, Patent Literature <NUM> and Patent Literature <NUM> each describing a conventional method using a thin-plate-like gasket as a sealing element disclose a structure shown in <FIG>. In this method, an anode metal frame <NUM> to which an anode <NUM> is attached is provided with an anode gasket <NUM>, a cathode metal frame <NUM> to which a cathode <NUM> is attached is provided with a cathode gasket <NUM>, and a separator <NUM> is sandwiched by the one pair of (two) gaskets <NUM> and <NUM>.

However, as a result of studies conducted by the present inventors, it has been found that in the electrolyzer described above, when the separator <NUM> is sandwiched by a structure using the O-rings <NUM> or a structure using the two gaskets <NUM> and <NUM>, particularly when the separator <NUM> forming the electrolyzer is a porous membrane, there is a defect as follows. In any of the above-mentioned structures, holding the separator <NUM> is performed by using a plurality of sealing elements and sandwiching the edge part of the separator <NUM> by these elements, and at the same time, the leakage of an electrolyte or an electrolytically generated gas from the electrolyzer is prevented, and airtightness in the electrolyzer is maintained. For this reason, a plurality of sealing elements, such as gaskets and O-rings, is needed. Particularly in a filter press type electrolyzer in which a plurality of electrolyzers is assembled on top of each other, the number of sealing elements such as gaskets increases. When the number of sealing elements increases, for example, there have been some troubles, such as protrusion caused by positional deviation of the gaskets and liquid leakage due to the protrusion or the like. When a configuration, as shown in <FIG>, in which the separator is sandwiched using two gaskets is adopted, it takes time and effort to accommodate the membrane in the gaskets in assembling a large electrolyzer. Further, the separator can also be held in a state of being pulled out of the electrolyzer from between the two gaskets. However, in the case where such a configuration using two gaskets is adopted, when a diaphragm (separator) is used instead of an ion exchange membrane, an electrolyte or an electrolytically generated gas may leak out of the electrolyzer through a small gap formed by the two gaskets, as shown in <FIG>.

Further, in the electrolyzer as described above, as another conventional method using a gasket, there is the following structure disclosed in Patent Literature <NUM>. Specifically, a structure formed using one gasket <NUM>, as shown in <FIG>, is known. The gasket <NUM> has a first surface <NUM> being in contact with the anode metal frame <NUM> and a second surface <NUM> being in contact with the cathode metal frame <NUM> and is provided with a slit <NUM> that forms a ring shape and opens toward the inside of the electrolyzer. In more detail, as shown in <FIG>, an original part <NUM> is set from the longitudinal upper end to the middle part of the gasket <NUM>, the lower part of the original part <NUM> is set as a slit-forming part <NUM>, and in the central part of the slit-forming part <NUM>, the slit <NUM> having a structure such that it extends approximately in parallel with the fast surface <NUM> and the second surface <NUM> of the gasket <NUM> and opens toward the inside of the electrolyzer is provided. In this example, the edge part of the separator <NUM> is accommodated in the slit <NUM>, and the separator <NUM> is held by the gasket <NUM> having the above-described structure.

According to the gasket <NUM> having the above-described structure, the gasket <NUM> is composed of a single element, and therefore, for example, there is no risk of the leakage of an electrolyte or an electrolytically generated gas from the edge part of the gasket, which occurs when the separator is sandwiched by a plurality of gaskets as shown in <FIG>. For this reason, when a gasket having the structure shown in <FIG> is used, the leakage rate of an electrolyte or an electrolytically generated gas can be reduced as compared with the case of using a gasket having the structure shown in <FIG>.

However, as a result of studies conducted by the present inventors, it has been found that when the gasket of the structure shown in <FIG> is used, there are problems described below. When a separator is held by a gasket having a structure as shown in <FIG>, it is necessary to form the slit <NUM> inside the thin-plate-like (sheet-like) gasket <NUM> in such a way as to extend in parallel with the first surface <NUM> and the second surface <NUM> of the gasket <NUM>. On the other hand, in order to further reduce the leakage rate of an electrolyte or an electrolytically generated gas, the accuracy of the length and thickness of the slit <NUM> to be formed is required, and therefore high skill is required for production. Further, when the separator is held in a gasket having the structure shown in <FIG>, it is necessary to firmly accommodate the edge part of the thin-plate-like separator <NUM> deep inside the slit <NUM> in such a way as not to form a gap, but it is not easy to do so. For this reason, it takes time and effort to install the separator, and there is also a problem that workability is poor in addition to the difficulty in production.

Patent Literature <NUM> mentioned above describes that the following structure is adopted in order to solve the above-described defect. There is disclosed a structure provided with a division part that continuously divides, in a first surface and a first part, the first portion into the surfaces that separately form the slit, or a division part that continuously divides, in a second surface and a second part, the second part into the surfaces that separately form the slit. When the separator is accommodated in the slit, the first part or the second part is turned up by this division part to accommodate the separator in the slit. However, in order to be able to install the separator to the gasket in this way, a division part must be formed at the slit, and the structure of the gasket is considerably complicated. Accordingly, in the case of adopting a structure as described above, means for improving the workability of installing the separator to the gasket increases the difficulty in production, making the work more complicated, and the production cost of the gasket increases. Furthermore, in the above-described configuration, when the difference in the thickness of the separator and the slit is small, it is extremely difficult to firmly hold the separator deep inside the slit of the gasket.

Furthermore, in the gasket of the structure described in Patent Literature <NUM> mentioned above, there is no problem as described above, but according to studies conducted by the present inventors, there are other important technical problems as follows. In the gasket of the structure described in Patent Literature <NUM>, when the separator is installed to the gasket, the separator is disposed in the middle of the interval formed by the anode and the cathode facing each other. Thus, when the separator is held using the above-described gasket, the separator is structurally in a state where it is not in contact with any of the anode and the cathode, as shown in <FIG>. For this reason, the thin sheet-like separator is unlikely to be fixed firmly, an unstable state where the separator is bent left and right continues during electrolysis operation, and the separator always causes a contact rubbing phenomenon with the anode and cathode, and therefore it is not possible to prevent breakage of the separator at an early stage. That is, in the above-described conventional techniques, there is a defect related to the durability of the held separator in addition to the above-mentioned problems.

Patent Literature <NUM> describes an ion exchange membrane electrolytic cell equipped with a gas diffusion electrode.

Patent Literature <NUM> describes a gas diffusion electrode equipped ion exchange membrane electrolyzer.

Patent Literature <NUM> relates to a gasket used in an electrolytic cell for alkaline water electrolysis, and to a membrane-electrode-gasket complex for alkaline water electrolysis, and an alkaline water electrolytic cell provided with the same.

Patent Literature <NUM> describes an alkaline water electrolysis device which prevents an alkaline aqueous solution from leaking.

An object of the present invention is to provide an electrolyzer gasket having a highly practical value as described below, and an electrolyzer using the same. That is, the electrolyzer gasket has a simple structure and can easily be produced; a separator can simply be attached by an extremely easy handling(action) using the gasket; the separator can stably be held without being bent during electrolysis operation, and therefore the electrolyzer gasket has excellent durability of the separator during the electrolysis operation and can effectively prevent leakage of an electrolyte or an electrolytically generated gas from the electrolyzer, which is a basic function of a gasket.

The above-described object is achieved by the present invention as defined in the appended claims and as described below.

The present invention provides an electrolyzer comprising an electrolyzer gasket incorporated in the electrolyzer, comprising: an anode; a cathode; and a sheet-like separator that isolates the anode and the cathode, the electrolyzer gasket being for holding the separator, wherein.

The present invention provides the electrolyzers as defined in the appended depending claims as preferred embodiments of the above-described electrolyzer.

According to the present invention, it can be realized to provide an electrolyzer comprising an electrolyzer gasket having a highly practical value as described below. That is, the electrolyzer gasket has a simple structure and can easily be produced; a separator can simply be attached by an extremely easy handling (action) using the gasket; the separator can stably be held without being bent during electrolysis operation, and therefore the electrolyzer gasket has excellent durability of the separator during the electrolysis operation and can effectively prevent leakage of an electrolyte or an electrolytically generated gas from the electrolyzer, which is a basic function of a gasket.

In detail, according to the present invention, configuring the structure of the electrolyzer gasket in such a way as to have a particular notch as described below makes it possible to provide an electrolyzer gasket being such that: the separator can stably be held by accommodating the edge part (end part) of the separator into a desired state in the notch; the separator can simply be attached because the handling required for holding the separator is easy, and the gasket has therefore excellent workability; and the production cost is low. That is, the above-described effects can be obtained by configuring a structure in which a notch, which is described below, is formed. That is, the structure is such that when the electrolyzer gasket including a single picture-frame-shaped thin-plate-like frame having approximately the same shape as the anode metal frame and the cathode metal frame is incorporated into an electrolyzer, a notch having a difference in level of approximately the same thickness as the thickness of the separator, the notch formed by thinly scraping off, in a uniform thickness, a region including an edge on the anode or the cathode of the thin-plate-like frame, is formed on either the first surface being in contact with the anode metal frame or the second surface being in contact with the cathode metal frame.

According to the present invention, by applying the electrolyzer gasket having a notch of the above-described particular structure to an electrolyzer, the edge part of the separator is accommodated in a gap formed between the notch and the anode metal frame or the cathode metal frame, and therefore the central part of the accommodated separator is held on either the surface of the anode and the surface of the cathode in a nearer state, so that a bend, a wrinkle, or torsion is less likely to occur to the separator, and it is possible to hold the separator stably in a normal state for a long period of time without allowing an unreasonable load to apply or causing damage to the separator.

Further, when the electrolyzer gasket used in the present invention is applied to an electrolyzer, the whole surface of one surface of the separator, excluding the edge part accommodated in the gap, is held in a state of being in contact with the anode or the anode fine mesh attached to the anode, or being in contact with the cathode or the cathode fine mesh attached to the cathode, and is not held in an unstable state in the middle of the anode and the cathode, which is different from the case where a conventional gasket is used. For this reason, by applying the electrolyzer gasket of the present invention to an electrolyzer, a bend, a wrinkle, or torsion is less likely to occur to the held separator, and therefore the above-described effect of holding the separator stably in a normal state for a long period of time without allowing an unreasonable load to apply or causing damage to the separator is enhanced.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In describing the present invention in detail, an electrolyzer gasket used in the present invention will be first described with reference to <FIG> that illustrates one example schematically showing the structure of the electrolyzer gasket of the present invention.

As shown in <FIG>, an electrolyzer gasket <NUM> used in the present invention has a first surface <NUM> being in contact with an anode metal frame <NUM> and a second surface <NUM> being in contact with a cathode metal frame <NUM>, and the electrolyzer gasket <NUM>, the anode metal frame <NUM>, and the cathode metal frame <NUM> all have an opening in the central part, and have a shape of a picture-frame-shaped square, circle, or the like. The electrolyzer gasket, exemplified in <FIG>, has a structure obtained by forming a notch <NUM> having a difference in level of approximately the same thickness as the thickness of a separator <NUM>, the notch formed, on the first surface <NUM> of the electrolyzer gasket <NUM> composed of a picture-frame-shaped thin-plate-like frame, by thinly scraping off, in a uniform thickness, a region including an edge on the anode of the thin-plate-like frame from near the center of the thin-plate-like frame to the edge on the anode chamber side. As a result, as shown in <FIG> and <FIG>, when the electrolyzer gasket is used for an electrolyzer, the edge part of the separator <NUM> is easily accommodated in the inside (level difference part) of the notch <NUM> and is in a state of being strongly held in a gap between the electrolyzer gasket <NUM> and the anode metal frame <NUM>. In the example of <FIG>, the notch part <NUM> is provided on the first surface <NUM> being in contact with the anode metal frame <NUM>, but instead, a structure in which the notch <NUM> is provided on the second surface <NUM> being in contact with the cathode metal frame <NUM> may be configured.

Numeral <NUM> in <FIG> denotes an insulating stopper, which is an element for preventing the up and down movement of the electrolyzer gasket <NUM> and preventing the gasket from protruding from the metal frame when the separator <NUM> is held. As shown in <FIG>, the stopper is attached in a state of being in close contact with the outer peripheral surface of the electrolyzer gasket <NUM>. The shape of the stopper <NUM> conforms to the shape of the electrolyzer and has a circular or rectangular frame structure. The stopper <NUM> can improve the airtightness in the electrolyzer <NUM> (see <FIG>, etc.) by preventing displacement of the gasket, and therefore the stopper <NUM> is effective means in the case of a large capacity electrolyzer in which a large number of cells are stacked or in the case of performing operation under pressurization. Note that <FIG> describes an example where the electrolyzer is assembled with a pair of an anode chamber and a cathode chamber, but the same applies to an electrolyzer in which a plurality of anode chambers and cathode chambers is stacked.

A plate-like or mesh-like anode <NUM> composed of any one of materials selected from the group consisting of an expanded mesh, a perforated plate, a wire mesh, and electrically conductive electrode materials each having a shape similar to any one of the expanded mesh, the perforated plate, and the wire mesh, and each having a large number of holes is attached at the opening formed in the central part of the anode metal frame <NUM>. Further, a plate-like or mesh-like cathode <NUM> composed of any one of materials selected from the group consisting of an expanded mesh, a perforated plate, a wire mesh, and electrically conductive electrode materials each having a shape similar to any one of the expanded mesh, the perforated plate, and the wire mesh, and each having a large number of holes is attached at the opening formed in the central part of the cathode metal frame <NUM>. The separator <NUM> is installed in such a way that the edge part (end part) thereof is held in the previously described notch <NUM> of the electrolyzer gasket <NUM> and the whole surface of one surface of the separator <NUM> excluding the held part is in a state of being in contact with the anode <NUM>.

<FIG> is a schematic diagram for explaining a configuration of holding the separator <NUM> in the electrolyzer gasket <NUM> used in the present invention. The electrolyzer gasket <NUM> in the example shown in <FIG> is composed of a single picture-frame-shaped thin-plate-like frame, and the notch <NUM> in a state where a region from near the center of the frame toward the edge on the anode chamber side to the edge is thinly scraped off in a uniform thickness is formed on one surface (surface on anode) of the frame. The notch <NUM> has a structure having approximately the same thickness (difference in level) as the thickness of the separator <NUM>. As shown in <FIG>, the outer periphery part of the separator <NUM> is accommodated in the gap formed between the anode metal frame <NUM> and the notch <NUM>, and is in a state of being accommodated in the notch <NUM>. The picture-frame-shaped sheet-like frame that forms the electrolyzer gasket <NUM> may have approximately the same shape as the anode metal frame and the cathode metal frame, and examples of the shape of the appearance include a rectangular shape and a circular (ring) shape.

<FIG> is a schematic section view for explaining the first embodiment of the electrolyzer gasket used in the present invention, used for an alkaline water electrolyzer <NUM> as an electrolyzer. In alkaline water electrolysis which is performed using the alkaline water electrolyzer <NUM>, a <NUM>%-by-mass to <NUM>%-by-mass KOH aqueous solution or NaOH aqueous solution is used as an electrolyte. When this electrolyte is supplied to an anode chamber <NUM> and a cathode chamber <NUM>, and electrolysis is performed, the electrolyte and an oxygen gas are discharged outside the system from the anode chamber <NUM>, and the electrolyte and a hydrogen gas are discharged outside the system from the anode chamber <NUM>. The discharged electrolytes are mixed outside the system and circulated into the anode chamber <NUM> and the cathode chamber <NUM>, and thus continuous electrolysis is performed.

As exemplified in <FIG>, the alkaline water electrolyzer <NUM> of the present invention has an anode metal frame <NUM>, an anode <NUM> attached to the anode metal frame <NUM>, the anode chamber <NUM> including the anode <NUM>, a cathode metal frame <NUM> having the same shape as the anode metal frame <NUM>, a cathode <NUM> attached to the cathode metal frame <NUM>, and a separator <NUM> which is for isolating the anode <NUM> and the cathode <NUM> and is provided between the anode <NUM> and the cathode <NUM>. The characteristic of the alkaline water electrolyzer <NUM> is in that the separator <NUM> is held in the state as shown in <FIG> by the electrolyzer gasket <NUM> which is sandwiched between the anode metal frame <NUM> and the cathode metal frame <NUM> and has a particular shape. That is, as shown in <FIG>, by using the electrolyzer gasket <NUM> of the present invention, having the notch <NUM>, the edge part of the separator <NUM> can easily be accommodated in a tight state in the gap formed between the electrolyzer gasket <NUM> and the anode metal frame <NUM>. As a result, the configuration is made such that approximately the whole surface of the surface on the anode of the separator <NUM> is held in a state of being nearer to the anode <NUM>. The above description is made on the example where the alkaline water electrolyzer <NUM> is configured in such a way as to bring the separator <NUM> nearer to the anode <NUM> side to hold the separator <NUM>, as shown in <FIG>, but the alkaline water electrolyzer <NUM> can also be configured in such a way as to bring the separator <NUM> nearer to the cathode <NUM> side to hold the separator <NUM> in a similar manner as described above, and the effects of the present invention can be obtained similarly in this case as well.

The anode metal frame <NUM> has an opening for forming the anode chamber in the central part. For example, the shape of the appearance is picture-frame-shaped, such as rectangular-shaped or circular (ring)-shaped. The anode <NUM> is attached at the opening of the anode metal frame <NUM>. The anode <NUM> is composed of an expanded mesh, a perforated plate, a wire mesh, or any one of electrically conductive electrode materials each having a shape similar to any one of the expanded mesh, the perforated plate, and the wire mesh, and each having a large number of holes. The cathode metal frame <NUM> has the same shape as the anode metal frame and has a picture-frame shape, such as a rectangular shape or a circular shape, having an opening for forming a cathode chamber in the central part. The cathode <NUM> is attached at the opening of the cathode metal frame <NUM>. The cathode <NUM> is composed of an expanded mesh, a perforated plate, a wire mesh, or any one of electrically conductive electrode materials each having a shape similar to any one of the expanded mesh, the perforated plate, and the wire mesh, and each having a large number of holes.

In the alkaline water electrolyzer of the first embodiment, a nickel-plated iron plate, nickel, or a nickel alloy is used for both of the anode <NUM> and the cathode <NUM> composed of an electrically conductive electrode material. Each of the anode metal frame <NUM> and the cathode metal frame <NUM> can also be formed with a nickel-plated iron plate, nickel, or a nickel alloy, which is the same as the material for the anode <NUM> and the cathode <NUM>. When these are formed with the same material, the anode <NUM> and the cathode <NUM> can be attached by means of welding or the like to the surfaces on the separator <NUM> side of the anode metal frame <NUM> and the cathode metal frame <NUM>, respectively.

The electrolyzer gasket <NUM> that characterizes the electrolyzer of the present invention is composed of a single picture-frame-shaped thin-plate-like frame having approximately the same shape as the anode metal frame <NUM> and the cathode metal frame <NUM>. As shown in <FIG>, the electrolyzer gasket <NUM> is sandwiched in a tight state between the anode metal frame <NUM> and the cathode metal frame <NUM>. As shown in <FIG>, the electrolyzer gasket <NUM> has the first surface <NUM> being in close contact with the anode metal frame <NUM> and the second surface <NUM> being in close contact with the cathode metal frame <NUM>. The electrolyzer gasket <NUM> is characterized in that the notch <NUM> having a particular shape is formed on any one of the first surface <NUM> and the second surface <NUM>.

Hereinafter, the details on the notch <NUM> provided on the first surface <NUM> will be described with reference to <FIG> and <FIG>. The notch <NUM> has a shape obtained by thinly scraping off, in a uniform thickness, a region including the edge from near the center of the picture-frame-shaped thin-plate-like frame of the electrolyzer gasket <NUM> to the edge on the anode chamber <NUM> side, and by the notch <NUM>, a sunken surface having a difference in level with a particular thickness with respect to the first surface <NUM> is formed on the first surface <NUM>.

As shown in <FIG>, the difference in level (thickness) W formed by the notch <NUM> has approximately the same thickness as the thickness M of the separator <NUM>. The electrolyzer gasket of the present invention has a structure in which the notch <NUM> having the above-described particular shape is formed, and therefore the edge part of the separator <NUM> can easily be accommodated in the gap formed between the notch <NUM> and the anode metal frame <NUM> and the held part of the separator <NUM> can be made into a tight state, as shown in <FIG>. As shown in <FIG>, by using the electrolyzer gasket <NUM> of the present invention, having the notch <NUM> having the above-described particular shape, for an electrolyzer, the separator <NUM> is held in a state where the whole surface facing the anode <NUM> is nearer to the surface of the anode <NUM>. That is, by using the electrolyzer gasket used in the present invention, the separator <NUM> is in contact with the surface of the anode <NUM> and held in a stable state on the anode <NUM> side without being held in the middle of the anode <NUM> and the cathode <NUM>, which is different from the case where a gasket of the conventional techniques is used.

As described above, when the separator <NUM> is held using the electrolyzer gasket <NUM> in an electrolyzer, the whole surface of one surface of the separator <NUM>, excluding the edge part of the separator <NUM> accommodated in the notch <NUM>, is held stably in a state of being fixed near the surface of the anode <NUM>, as shown in <FIG>, and therefore a bend, a wrinkle, or torsion is less likely to occur to the separator, which suppresses that unreasonable load is applied. For this reason, causing damage to the separator is suppressed, and therefore holding the separator in the electrolyzer stably in a normal state for a long period of time can be realized. As mentioned previously, the above description has been made by the example where the electrolyzer is configured in such a way as to bring the separator <NUM> nearer to the anode <NUM> side to hold the separator <NUM>. Note that when the electrolyzer is configured in such a way as to bring the separator <NUM> nearer to the cathode <NUM> side to hold the separator <NUM> in a similar manner as those described above, the above-described effects of the present invention are obtained as well.

In the alkaline water electrolyzer <NUM> exemplified above, a corrosion resistant coating may be applied on the surface of the anode metal frame <NUM> or the cathode metal frame <NUM> in order to prevent crevice corrosion which occurs between the anode metal frame <NUM> or the cathode metal frame <NUM> and the electrolyzer gasket <NUM> sandwiched in a tight state although it depends on the type of the electrolyte to be used and the characteristics of the gases to be generated.

In addition, an elastic body having corrosion resistance against an electrolyte and an electrolytically generated gas is preferably used as a material for forming the electrolyzer gasket <NUM>. For example, elastic bodies given below can appropriately be selected and used. Natural rubber (NR), styrene butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), silicone rubber (SR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), fluorine rubber (FR), isobutylene-isoprene rubber (IIR), urethane rubber (UR), chlorosulfonated polyethylene rubber (CSM), and the like can be used.

The material for forming the separator <NUM> is not particularly limited as long as it is a separator having permeability to an aqueous solution. For example, an asbestos separator, non-woven fabric of PPS (polyphenylene sulfide), or a chemically resistant non-woven fabric immersed with a polymer, such as PTFE (polytetrafluoroethylene) or PSF (polysulfone), is suitably used. The thickness of the separator is about <NUM> to about <NUM> and is not particularly limited.

The electrolyzer gasket <NUM> used in the present invention includes an original part <NUM> in the upper part (outer periphery side of thin-plate-like frame) where the notch is not formed and a notch-forming part <NUM> in the lower part (central side of thin-plate-like frame), as shown in <FIG>. Further, the electrolyzer gasket <NUM> used in the present invention, when set in an electrolyzer, has the first surface <NUM> being in close contact with the anode metal frame <NUM> and the second surface <NUM> being in close contact with the cathode metal frame <NUM>. As previously described, on the first surface <NUM> of the electrolyzer gasket <NUM>, the notch <NUM> designed in such a way as to have approximately the same thickness (difference in level) as the thickness of the separator <NUM> is provided at the notch-forming part <NUM> in a region from the boundary with the above-described original part <NUM> to the edge of the notch-forming part <NUM>. The original part <NUM> in the upper part (on outer periphery side) from the region of the notch-forming part <NUM> of the first surface <NUM> forming the electrolyzer gasket <NUM>, when set in the electrolyzer, is in a state of being in surface contact with the anode metal frame <NUM>.

The signs for indicating the dimensions of each part of the electrolyzer gasket <NUM> for the present invention are shown in <FIG>. Specific dimensions are appropriately set according to the sizes of individual electrolyzers. In addition, <FIG> shows the electrolyzer gasket <NUM> before being incorporated and set into an electrolyzer in a state where respective components are not in close contact with each other. Hereinafter, description will be made with reference to <FIG>.

The length L of the notch <NUM> may appropriately be designed to the length to such an extent that the separator <NUM> can be held in accordance with the size of the electrolyzer and the electrode reaction area, and is, for example, about <NUM> to about <NUM>, and preferably <NUM> to <NUM>. The depth (also referred to as difference in level or thickness) W of the notch <NUM> may appropriately be set according to the thickness of the separator, and is, for example, about <NUM> to about <NUM>. In the present embodiment, the depth W of the notch <NUM> is approximately equal to the thickness M of the separator, and is, for example, about <NUM>. The length C of the electrolyzer gasket <NUM> (width C of frame) is about <NUM> to about <NUM>, the length A of the original part <NUM> is about <NUM> to about <NUM>, the length B of the notch-forming part <NUM> is about <NUM> to about <NUM>, and the thickness M of the separator is about <NUM> to about <NUM>. According to studies conducted by the present inventors, the ratio of the length A of the original part <NUM> to the length B of the notch-forming part <NUM> is preferably A:B = about <NUM>:<NUM> to <NUM>:<NUM> in order to sandwich the separator <NUM> in a tight state and in order not to allow liquid leakage to occur. However, the relationship is not limited to this because the relationship is influenced by the properties (such as strength, elasticity, and stretchability) of the gasket to be used.

On the other hand, the whole surface of the second surface <NUM> of the electrolyzer gasket <NUM> shown in <FIG> is in surface contact with the cathode metal frame <NUM>, and there exists no gap between the electrolyzer gasket <NUM> and the anode metal frame <NUM> and between the electrolyzer gasket <NUM> and the cathode metal frame <NUM>, and therefore an electrolyte in the electrolyzer <NUM> and an electrically generated gas does not leak outside from these contact surfaces.

The edge parts of both of the upper end and the lower end of the separator <NUM>, after being inserted in the notch <NUM> of the electrolyzer gasket <NUM> (hereinafter, also simply referred to as "gasket"), are preferably compressed by a tie rod <NUM> (see <FIG>, <FIG>) or other pressing means, such as oil pressure means (not shown), from both sides of the anode metal frame <NUM> and the cathode metal frame <NUM>. By configuring the electrolyzer gasket <NUM> in this way, the outer periphery part of the separator <NUM> is: accommodated in a tight state in the notch <NUM> of the gasket <NUM>; more rigidly held by each side inside the notch <NUM> of the gasket <NUM>; in a tight state by the upper part of the first surface <NUM> of the gasket <NUM>, the whole surface of the second surface <NUM> of the gasket <NUM>, the anode metal frame <NUM>, and the cathode metal frame <NUM>; and tightly sealed. For this reason, the leakage of an electrolyte and an electrolytically generated gas from the inside of the electrolyzer <NUM> to the outside can more surely be prevented.

When the electrolyzer gasket <NUM> is used for an electrolyzer, the whole surface of one surface of the separator <NUM>, facing an electrode, is in a state of being in contact with the anode <NUM> and the anode metal frame <NUM>, or being in contact with the cathode <NUM> and the cathode metal frame <NUM>. That is, in the example shown in <FIG>, the whole surface of surface on the anode of the separator <NUM> the outer periphery part (edge part) of which is accommodated in the notch <NUM> of the electrolyzer gasket <NUM> is in a state of being contact with the anode metal frame <NUM> and the anode <NUM>. For this reason, with respect to the shapes of the cross sections of the contact parts, all of the contact part between the anode metal frame <NUM> and the gasket <NUM>, the contact part between the surface on the anode of the separator <NUM> in the electrolyzer gasket <NUM> and the anode metal frame <NUM>, and the contact part between the anode <NUM> and the separator <NUM> are in a state of being disposed and held in one straight line.

Accordingly, the separator <NUM> is not held unstably in the middle of the anode <NUM> and the cathode <NUM>, and is held in a state of being along with the surface of the anode <NUM> (a state of being stacked) and in a state of one fixed plane. For this reason, during electrolysis operation, a bend, a wrinkle, or torsion does not occur in the separator <NUM>, and an unreasonable load is not applied to the separator <NUM>, so that causing damage to the separator <NUM> is remarkably suppressed. As a result, the separator <NUM> can be used stably for a long period of time, and therefore effective utilization of resources and an economical effect can be expected. Note that by setting the disposition at the time when the separator <NUM> is held to a state where a plurality of contact parts described above is held on one straight line, the rate of occurrence of a bending part on the separator <NUM> is lowered, so that the separator damage rate can be reduced. However, the state where the whole surface of one surface of the separator <NUM>, excluding the held part, and the anode <NUM> or the cathode <NUM> are in contact with each other does not have to be configured depending on the position of installing the anode <NUM> or the cathode <NUM> as long as the gap therebetween is narrow.

As shown in <FIG>, an anode chamber frame <NUM> that forms the anode chamber <NUM> is connected to the rear surface of the anode metal frame <NUM>, and a cathode chamber frame <NUM> that forms the cathode chamber <NUM> is connected to the rear surface of the cathode metal frame <NUM>. The anode chamber frame <NUM> and the cathode chamber frame <NUM> can be formed with the same material as the anode metal frame <NUM> and the cathode metal frame <NUM>, respectively. Further, all of the anode <NUM>, the anode metal frame <NUM>, the anode chamber frame <NUM>, the cathode <NUM>, the cathode metal frame <NUM>, and the cathode chamber frame <NUM> can also be formed with the same material, such as a nickel-plated iron plate, nickel, or a nickel alloy. Note that the first surface <NUM> or the second surface <NUM> of the electrolyzer gasket may be bonded to the anode metal frame <NUM> or the cathode metal frame <NUM>, with which the first surface <NUM> or the second surface <NUM> is in contact, with an adhesive. In the case of a large-scale real machine, cell assembly may be performed standing the cell on the spot, and therefore use of an adhesive is effective in such a case. On the other hand, in the case of a small-sized machine, cell assembly is often performed laying it on its side, and in this case, an adhesive is unnecessary.

In the first embodiment, the description has been made on the example where the notch <NUM> is provided at the notch-forming part <NUM> of the first surface <NUM> of the gasket <NUM>, wherein the first surface <NUM> is in contact with the anode metal frame <NUM>. In the second embodiment (not shown), the notch <NUM> is formed by providing the notch-forming part <NUM> at the second surface <NUM> of the gasket <NUM>, wherein the second surface <NUM> is on the opposite side of the first surface <NUM> and is in contact with the cathode metal frame <NUM>. In this example, the original part <NUM> which is in the upper part from the center of the second surface <NUM> of the gasket <NUM> is brought into surface contact with the cathode metal frame <NUM>, and on the other hand, the whole surface of the first surface <NUM> of the gasket <NUM> is brought into surface contact with the anode metal frame <NUM>. In this case, the configuration is made such that the cathode metal frame <NUM> and the cathode <NUM> are disposed on the same plane. For this reason, the whole surface of the separator <NUM> whose edge part is accommodated and held in the notch <NUM> provided on the cathode of the gasket <NUM> is in a state of being in contact with the cathode metal frame <NUM> and the cathode <NUM>, and the separator <NUM> is held in a state of one plane such that the separator <NUM> is fixed in a state of being along the surface of the cathode <NUM> (in a state where the separator <NUM> is stacked on the surface).

Accordingly, also in the case of the second embodiment as well as the first embodiment, the central part of the separator <NUM> is not held in an unstable state in the middle of the anode <NUM> and the cathode <NUM> and is linearly held in a contact state along with the surface of the cathode <NUM>, which is different from the cases shown in <FIG> where a conventional gasket is used. For this reason, torsion does not occur to the separator <NUM>, an unreasonable load is not applied, so that the separator <NUM> can be used stably for a long period of time without causing damage to the separator <NUM>.

In the third embodiment, in addition to the configuration of the first embodiment or the second embodiment, an anode obtained by covering the surface on the separator <NUM> side of the anode <NUM> with an anode-activating catalyst is used as the anode <NUM>, and a cathode obtained by covering the surface on the separator <NUM> side of the cathode <NUM> with a cathode-activating catalyst is used as the cathode <NUM>. By configuring the electrolyzer in this way, enhancement of the performance of the electrolyzer can be achieved. Further, in order to enhance the performance of the electrolyzer of the present invention, it is preferable to attach, to the surface of the anode <NUM> on the separator <NUM> side, an anode fine mesh <NUM> on which an activated anode coating is applied and/or attach, to the surface of the cathode <NUM> on the separator <NUM> side, a cathode fine mesh <NUM> on which a activated cathode coating is applied.

In order to achieve further enhancement of the performance of the electrolyzer, a spring material <NUM> is preferably attached between the anode fine mesh <NUM> and the anode <NUM> and/or between the cathode fine mesh <NUM> and the cathode <NUM> to achieve a zero gap between the anode <NUM> and the cathode <NUM>. As the spring material, a cushion coil of a nickel base material can suitably be used. <FIG> shows an example of the electrolyzer in which the spring material <NUM> is attached between the cathode fine mesh <NUM> and the cathode <NUM>. By configuring the electrolyzer as shown in <FIG>, the zero gap between the anode <NUM> and the cathode <NUM> is achieved, so that further enhancement of the performance of the electrolyzer is achieved.

The electrolyzer gasket for the present invention is suitable for an alkaline water electrolyzer but can also be applied to an electrolyzer for brine electrolysis and other electrolyzers, such as electrolyzers for pure water electrolysis, electrolysis of unpurified water, bromide aqueous solution electrolysis, hydrochloric acid aqueous solution electrolysis, and sulfuric acid aqueous solution electrolysis. To apply the present invention to a brine electrolyzer, a cation exchange membrane is used as the separator <NUM>, the anode chamber <NUM> and the cathode chamber <NUM> of the electrolyzer are isolated by the cation exchange membrane, a sodium chloride solution is used as an anolyte, and a caustic alkali metal aqueous solution is adopted as a catholyte.

Further, the electrolyzer gasket and the electrolyzer of the present invention can also be applied in a pressurization system. Note that in the case of the pressurization system, both of the anode chamber and the cathode chamber are pressurized. On this occasion, cathode pressurization is preferable as operation management because there is a tendency that the purity of hydrogen collected from the cathode is increased by making the pressure on the cathode a little higher than the pressure on the anode to perform anode pressurization control. On the other hand, the cathode pressurization depends on the type of separator, and when a separator which easily permeates an electrolyte is used, weak cathode pressurization as weak as a water column of about <NUM>-H<NUM>O, or the same pressure is adopted.

Furthermore, the electrolyzer gasket and the electrolyzer of the present invention can also be applied not only to a unipolar system electrolyzer but also a bipolar system electrolyzer.

Claim 1:
An electrolyzer comprising an electrolyzer gasket (<NUM>) incorporated in the electrolyzer, comprising: an anode (<NUM>); a cathode (<NUM>); and a sheet-like separator (<NUM>) that isolates the anode (<NUM>) and the cathode (<NUM>), the electrolyzer gasket (<NUM>) being for holding the separator (<NUM>), wherein
the electrolyzer has: a picture-frame-shaped anode metal frame (<NUM>) having an opening for forming an anode chamber (<NUM>) in a central part; and a cathode metal frame (<NUM>) having the same shape as the anode metal frame and having an opening for forming a cathode chamber (<NUM>) in a central part, the anode (<NUM>) is attached at the opening of the anode metal frame (<NUM>), the cathode (<NUM>) is attached at the opening of the cathode metal frame (<NUM>), and the electrolyzer gasket (<NUM>) is sandwiched in a tight state between the anode metal frame (<NUM>) and the cathode metal frame (<NUM>),
the electrolyzer gasket (<NUM>) comprises a single picture-frame-shaped thin-plate-like frame having approximately the same shape as the anode metal frame (<NUM>) and the cathode metal frame (<NUM>),
the picture-frame-shaped thin-plate-like frame has: a first surface (<NUM>) being in close contact with the anode metal frame (<NUM>); and a second surface (<NUM>) being in close contact with the cathode metal frame (<NUM>), and has a structure obtained by forming, on any one of the first surface (<NUM>) and the second surface (<NUM>), a notch (<NUM>) having a difference in level of approximately the same thickness as the thickness of the separator (<NUM>), the notch (<NUM>) formed by thinly scraping off, in a uniform thickness, a region including an edge on the anode or the cathode of the thin-plate-like frame, and
an edge part of the separator (<NUM>) is accommodated in a gap formed between the notch (<NUM>) and the anode metal frame (<NUM>) or the cathode metal frame (<NUM>), and the separator (<NUM>) is held in a state of being nearer to the surface of the anode or the surface of the cathode.