KR890001490B1 - Electrolytic cell and gasket for electrolytic cell - Google Patents

Abstract

An electrolytic cell has a separator between anode and cathode and forming two compartments, and at least one electrically insulating gasket between the electrodes and having projections and recesses to cooperate with corresponding recesses and projections of the anode and/or cathode. Gasket is pref. of planar frame shape, the space inside the frame forming part of a compartment, and the gasket may have the formations on both surfaces and cooperate with a further gasket. The gasket is pref. 1-20mm thick and has the projections and recesses spaced by 1-20cm. The separator is a microporous diaphragm and is clamped between a pair of gaskets. Cell is pref. of filter- press type with altermating anodes and cathodes.

Description

Electrolyzer and Gasket for Electrolyzer

1, 3 and 5 are perspective views showing a part of a pair of gaskets associated with a metal electrode forming part of an electrolytic cell.

2, 4 and 6 are cross-sectional views of the metal electrodes and associated gasket pairs shown in FIGS. 1, 3 and 5, respectively, assembled together.

* Detailed description of the main parts of the drawings

1, 10, 20: electrode 2: hole

3, 21, 22: Lip 4, 7, 13, 16: Gasket

5, 18, 11, 14, 17: protrusions 6, 9, 12, 15, 18, 17: recesses

The present invention relates to an electrolytic cell and a gasket for the electrolytic cell.

It is known that an electrolytic cell consists of a plurality of positive and negative electrodes separated from adjacent negative electrodes by a separator that separates the electrolytic cell into a plurality of positive and negative types. The anode compartment of such an electrolytic cell is equipped with an apparatus for properly supplying an electrolytic extract from a common header to an electrolytic cell and an apparatus for removing an electrolytic product from an electrolytic cell. Similarly, the cathode compartment of the electrolyzer is equipped with a device for removing electrolytic products from the electrolyzer, optionally with a device for supplying water or other fluid to the electrolyzer.

The separator in the electrolyzer is a special diaphragm that allows electrolyte to flow from the anode compartment to the cathode compartment of the cell, or is an almost impermeable membrane that is ion selective permeable, such as cation selective permeable, Allow selective flow of ionic species between the cathode compartments.

Such electrolysers are used, for example, in the electrolysis of aqueous solutions of alkali metal chlorides. When such a solution is electrolyzed in a diaphragm type electrolyzer, the solution is fed to the anode compartment of the electrolyzer, the chlorine produced in the electrolysis is removed from the anode compartment of the electrolyzer, and the alkali metal chloride solution passes through the diaphragm and is produced in electrolysis. Hydrogen and alkali hydroxides are removed from the cathode compartment in the form of alkali metal chlorides and alkali metal hydroxides. When an aqueous alkali metal chloride solution is electrolyzed in a membrane-type electrolyzer containing a cationic selective permeable membrane, the solution is fed to the anode compartment, and the chlorine and spent alkali solution in the electrolyte is removed from the anode compartment, and the alkali metal ion These are transported across the membrane to the cathode compartment of the electrolyzer, where water or dilute alkali metal hydroxide solution is supplied, and the hydrogen and alkali metal hydroxide solution produced by the reaction of the alkali metal ions with the hydroxyl ions are removed from the cathode compartment of the electrolyzer.

The electrolytic cell of the type described above is used in the production of chlorine and sodium hydroxide, in particular by electrolysis of aqueous sodium chloride solution.

Many different configurations of electrolyzers are known. For example, a filter press type electrolyzer may contain up to 150 more anodes and cathodes, but a greater number of anodes, such as 50 anodes alternated with 50 cathodes. The cathodes are alternately included.

Such electrolyzers include a number of gaskets. For example, in a filter press type electrolytic cell, one or more gaskets are disposed between adjacent anodes and cathodes to electrically insulate the anodes and cathodes from each other, and also provide a space in the cell to form a cathode and cathode compartment. do.

In such electrolyzers, particularly filter press type electrolyzers comprising a large number of gaskets, it is difficult to place the gasket during assembly of the electrolyzer and to hold it in place when the gasket is subjected to increased pressure. Moreover, during use of the electrolyzer, the gasket slips and there is a risk of electrolyte leakage from the electrolyzer.

The present invention relates to an electrolyzer and a gasket in which the gasket is easily assembled and maintained at a predetermined position of the electrolyzer during assembly and use of the electrolyzer.

US Pat. No. 41,75025 describes a method for sealing a membrane by means of a gasket, called a frame, in which a membrane is formed in a filter press type electrolyzer and fixed between adjacent frames, the membrane having a larger surface area than the frame. .

In the electrolyzer, recesses are formed around the frame, and gaskets are fitted in the recesses to support the adjacent frames to hold the membrane in place.

In another embodiment a peripheral groove is provided in each adjacent frame and a gasket is fitted in each groove, and the membrane is fixed between the gaskets of the adjacent grooves.

According to the present invention, the gasket comprises at least one positive electrode and at least one negative electrode, a separator disposed between the positive electrode and the adjacent negative electrode and separating the electrolyzer into separate positive and negative compartments, and at least one gasket made of an electrically insulating material, the gasket Is provided with a plurality of protrusions and / or recesses adapted to interact with corresponding recesses and / or protrusions on the surface of the anode cathode or gasket adjacent thereto.

The present invention is not limited to being applied to a filter press type electrolyzer. However, the present invention is particularly suitable for use in such electrolyzers, in which a plurality of anodes and cathodes are alternately included and in which a plurality of gaskets are included, because of the difficulty of the correct placement of the gasket and the risk of slipping of the gasket. It is because it is such a filter press type electrolytic cell.

In the electrolytic cell the gasket is disposed adjacent to the anode and / or cathode and in this case the protrusions / or recesses on the surface of the gasket interact with the corresponding recesses and / or protrusions on the anode and cathode surfaces. Gaskets are disposed between adjacent anodes and cathodes.

The gasket has a frame structure so that the inner space of the frame provides a space for forming part of the anode or cathode compartment in the electrolyzer.

Alternatively, the anode and cathode of the electrolyzer are themselves disposed in separate gaskets. For example, each anode and cathode is disposed and held in a framed gasket, i.e., the groove of the gasket. In this case the protrusions and / or recesses on the surface of the gasket interact with the corresponding recesses and / or protrusions on the surface of another gasket adjacent thereto.

The gasket is generally planar and includes protrusions and / or recesses on one or both sides of the gasket, ie opposite.

It is preferred that the gasket comprises on the one hand both a protrusion and a recess.

Thus, the gasket includes a plurality of protrusions and / or recesses on both opposite sides thereof and is adapted to interact with corresponding recesses and / or protrusions on the surfaces of the anode and cathode or two gaskets adjacent the gasket.

The gasket may comprise any suitable shaped protrusion on its surface, and the recess will be shaped to interact with the protrusion. For example, the protrusion may be in the form of a stud on the surface of the gasket. The stud may have a rectangular shape, for example, a square or rectangular shape, or may have a cylindrical shape. The recessed portion may be shaped to interact with the shape of the protrusion, and the recessed portion may have a corresponding shape passing from one side of the gasket to the other side.

In a particular embodiment of the electrolyzer of the present invention, each positive electrode and negative electrode other than the terminal positive and negative electrodes is disposed between a pair of gaskets, the gaskets having a plurality of protrusions / or on at least one side of the gasket facing the positive or negative electrode. Wherein the anode or cathode comprises recesses on its surfaces, and the protrusions on one or both sides of the gasket penetrate the recess in the anode or cathode and the corresponding recess in the gasket opposite the anode or cathode. Interact with them.

The protrusions and / or recesses on the surface of the gasket should be distributed so that the desired result of the correct placement of the gasket during the assembly of the electrolytic cell is obtained and also ensure that the gasket is held in a predetermined position in the electrolytic cell during use of the electrolytic cell.

Generally, the protrusions and / or recesses will be spaced no more than 20 cm and may be spaced at small intervals up to 2 cm. However, this gap is given as a general guideline and is not intended to be limiting.

The thickness of the gasket at least partially determines the size of the positive or negative compartments of the electrolyzer. For example, the gasket can be 1-20 mm thick.

The protrusions must protrude from the surface of the gasket long enough to achieve the desired result of the correct placement of the gasket during assembly of the cell and ensure that the gasket is held in a predetermined position in the cell during use of the cell. Therefore, it is desirable that the protrusions fit relatively tightly in the recesses with which they interact.

The gasket should be made of an electrically insulating material. The gasket is preferably flexible and elastic in order to prevent leakage sealing in the electrolyzer.

Gaskets are suitably made of organic polymeric materials, the materials being based on, for example, polyolefins such as polyethylene or polypropylene, ethylene-flopropylene copolymers, ethylene-propylene-diene copolymers, natural rubber or styrene-butadiene rubbers. Hydrocarbon elastomers such as elastomers or chlorinated hydrocarbons such as polyvinyl chloride or polyvinylidene chloride. It is particularly preferable that the material of the gasket is chemically resistant to the liquid in the electrolytic cell, and when the electrolytic cell is used for the electrolysis of an aqueous alkali metal chloride solution, the material is for example polytetrafluoroethylene, polyvinyl chloride, polyvinylidene chloride, chlorine The treated ethylene-propylene copolymer, tetrafluoroethylene-hexa-fluoro-propylene copolymer, or a substrate having an outer layer of such a prolined polymer material.

In another embodiment of the invention, a gasket is provided for use in an electrolytic cell, the gasket comprising a plurality of protrusions and / or recesses on its surface.

The separator in the electrolytic cell may be of diaphragm or membrane type. In a diaphragm type electrolyzer, the separator positioned between adjacent anodes and cathodes to form a separate anode compartment and cathode compartment is microporous, and in use, electrolyte flows from the anode compartment to the cathode compartment via the diaphragm. Thus, the electrolyzer liquid produced when the alkali metal chloride aqueous solution is electrolyzed consists of an aqueous solution of alkali metal chloride and alkali metal hydroxide. In membrane-type electrolysers, the separator is essentially impermeable and in use the ionic species and the hydrated ionic species are moved across the membrane between the compartments of the electrolyzer. Thus, when the membrane is a cation exchange membrane, the cations move across the membrane and when the aqueous alkali metal chloride solution is electrolyzed, the electrolyzer liquid consists of an aqueous solution of alkali metal hydroxide.

If the separator to be used in the electrolyzer is a microporous diaphragm, the properties of the diaphragm depend on the nature of the electrolyte to be electrolyzed in the electrolyzer. Diaphragms must be resistant to degradation by electrolytes and electrolytic products, and when aqueous solutions of alkali metal chlorides are electrolyzed, the diaphragms must be made of fluorine-containing polymer materials, because such materials are chlorine produced in electrolysis. And generally resistant to chloride by alkali metal hydroxides. Microporous diaphragms may be included in other materials used, such as tetraproethylene-nuxafluoropropylene copolymers, vinylidene fluoride polymers and copolymers, and florinated ethylene-propylene copolymers, although polytetrafluoro Preferably made of ethylene.

Suitable microprocess diaphragms are described, for example, in British Patent No. 1503915, which discloses microporous diaphragms made of polytetrafluoroethylene having a microstructure of nodes interconnected by fine fibers. British Patent No. 1081046 describes a microporous diaphragm made by extruding particulate filler from a plate of ethylene with polytetraflo. Other suitable microporous diaphragms are known in the art.

If the separator to be used in the electrolyzer is a cation exchange membrane, the properties of the membrane also depend on the nature of the electrolyte to be electrolyzed in that electrolyzer. The membrane must be resistant to chlorides by electrolytes and electrolytic products, and when the aqueous solution of an alkali metal chloride is electrolyzed, the membrane contains a fluorine-containing polymer material containing a cation exchange group such as sulfonic acid, carboxylic acid or phosphoric acid groups, Or derivatives thereof or mixtures of two or more of these groups.

Suitable cation exchange membranes are, for example, those described in British Patents No. 1184321, 1402920, 14066673, 1455070, 1497748, 1497749, 1518387 and 1531068.

The separator is fixed in place in the electrolytic cell, for example by securing the separator to a gasket or by tightening between the surfaces of a pair of adjacent gaskets. The separator is provided at its surface with a number of holes in which the protrusions on the surface of the gasket adjacent thereto are arranged therein. These holes in the separator surface aid in the correct placement of the separator in the electrolytic cell.

Electrodes in an electrolytic cell are generally made of a metal or alloy and the nature of the metal or alloy depends on whether the electrode is to be used as an anode or a cathode and on the nature of the electrolyte to be electrolyzed in the electrolytic cell.

If an aqueous alkali metal chloride solution is electrolytically used and the electrode is used as the anode, the electrode is suitably made of a film forming metal or an alloy thereof, such as zirconium, niobium, tungsten or tantalum, more preferably made of titanium, The surface suitably has a coating of electrically conductive electrocatalytically active material. This coating consists of one or more platinum metals, ie platinum, rhodium, iridium, ruthenium, osmium and palladium and / or oxides of one or more of these metals. The coating of the white metal metal and / or oxide is present in a mixture with one or more non-noble metal oxides, for example titanium dioxide. BACKGROUND OF THE INVENTION Electrically conductive electrocatalytically active materials to be used as anode coatings in electrolytic baths of aqueous alkali metal chloride solutions and methods for attaching such coatings are known in the art.

If an aqueous alkali metal chloride solution is electrolytically used and the electrode is used as the cathode, it is appropriate that the electrode is made of iron or steel or other suitable metal such as nickel. The cathode may be coated with a material intended to reduce the hydrogen overpotential of electrolysis.

The electrode has a surface with at least partially pores. For example, it may be a perforated plate and may have a mesh surface (s), such as a woven net, or may comprise a number of spaced long members, such as a plurality of strips that are generally parallel to one another and placed vertically in an electrolytic cell.

The electrolytic cell can be a monopolar or bipolar electrolytic cell. That is, the electrolytic cell may include respective anodes and cathodes separated from each other, or the anodes and cathodes may be coupled to each other in the form of a bipolar electrode.

In the electrolytic cell, the anode compartment is equipped with a device for properly supplying electrolyte solution from the cavity header to the compartments and a device for removing the electrolyte product from the compartments. Similarly, the cathode compartment of the electrolyzer is equipped with a device for removing the electrolytic product from the compartment, and the device for supplying water or other fluid from the cavity header is optionally provided.

For example, when an electrolytic cell is used for electrolysis of an aqueous alkali metal chloride solution, the anode compartment of the electrolytic cell includes a device for supplying an aqueous alkali metal chloride solution to the compartment and a device for removing an aqueous solution of alkali metal chloride consumed from the compartment. The cathode compartment of is provided with a device for removing an electrolytic solution containing hydrogen and alkali metal hydroxide from the compartment, and optionally a device for supplying water or dilute alkali metal hydroxide aqueous solution to the cathode compartment.

The present invention will now be described with reference to the accompanying drawings.

The detailed configuration of the gasket and the whole electrode is not shown because it depends on the special structure of the electrolyzer. The figure illustrates a particular embodiment of the application of the principles of the present invention that can be readily applied to electrolyzers of any structure.

1 and 2, there is shown a plate-shaped metal electrode 1 which becomes an anode or a cathode in an electrolytic cell. The electrode comprises a plurality of holes 2 which are made by forming three slits on the surface of the electrode and folding the lip 3 back in a state substantially perpendicular to the surface of the electrode. The lip 3 is alternately arranged on one side and the other side of the electrode.

The gasket 4 disposed on one side of the electrode 1 is made of an elastic ethylene-propylene-diene copolymer and a protrusion 5 is formed on the surface of the gasket. The gasket 4 disposed on the other side of the electrode 1 also includes similarly shaped protrusions 8 and recesses 9.

When assembled into the electrolytic cell, the protrusions 5 on the surface of the gasket 4 pass through the holes 2 in the electrodes 1 and enter the recesses 9 of the gasket 7 on the opposite side of the electrode 1. . Similarly, the protrusion 8 in the gasket 7 passes through the hole 2 of the electrode 1 and enters the recess 6 of the gasket 4 on the opposite side of the electrode 1. The ribs 3 are likewise arranged in recesses 6 and 9 in the gaskets 4 and 7 respectively.

The gaskets 4, 7 comprise recesses and protrusions on the surfaces opposite the surfaces having the protrusions 5 and recesses 6 and the protrusions 8 and recesses 9, respectively. These protrusions and recesses interact with the holes and ribs in the electrodes lying adjacent to these opposite surfaces.

3 and 4 include protrusions 11 and recesses 12 formed by making a pair of parallel slits in the plate and alternately displacing the portion surrounded by the slits to one side and the other side of the plate. The plate shaped metal electrode 10 is shown. The gasket 13 located at one side of the electrode 10 is formed with protrusions 14 and recesses 15. Similarly, the gasket 16 located on the other side of the electrode 10 is also formed with a protrusion 17 and a recess 18.

The protrusions 14 and 17 on the surfaces of the gaskets 13 and 16, respectively, are placed on the recesses 12 of the 10, when assembled into the electrolytic cell, and the protrusions 11 on the electrode 10. ) Are respectively disposed on the recesses 15 and 16 on the surfaces of the gasket 13 and 16.

The embodiment shown in FIGS. 5 and 6 differs only in the form of recesses 19 in the electrode 20 from those shown in FIGS. 1 and 2. The recesses 19 are respectively bound by upright lips 21 and 22 which project alternately to one side and the other side of the electrode surface.

Claims (12)

An electrolyzer comprising a separator positioned between at least one anode and at least one cathode, an anode and an adjacent cathode, separating the electrolyzer into separate anode and cathode compartments, and one or more gaskets made of an electrically insulating material, comprising: 4) the protrusions 5 and / or recesses 6 interacting with the corresponding recesses 9 and / or protrusions 8 on the surface of the anode or cathode 1 or the gasket 7 adjacent thereto. An electrolytic cell comprising a. 2. An electrolytic cell according to claim 1, characterized in that the electrolytic cell is a filter press type comprising a plurality of anodes and cathodes (1, 10, 20) and a plurality of gaskets (4, 7, 13, 16). . 3. The gasket 4, 7 according to claim 1, wherein the gaskets 4, 7 interact with corresponding recesses 9 and / or protrusions 8 on their surface with an anode and / or a cathode 1. An electrolytic cell comprising a protrusion (5) and / or recesses (6). The electrolytic cell according to claim 1, wherein the gasket (4, 7) has a planar frame type structure having a space inside the frame which forms part of the anode or cathode (1) compartment. 5. The protrusions 5 and / or recesses 6, according to claim 1, 2 or 4, on the surface of the gasket 4 are corresponding recesses on the surface of another gasket 7 adjacent thereto. 6. (9) and / or interact with the protrusions (8). 5. The gasket (4, 7, 3, 16) according to any one of claims 1, 2, or 4, has protrusions (5, 8, 11, 14, 17) and recesses (6) on its surface. 9, 12, 15, 18, 19) characterized in that it comprises all of the electrolyzer. 7. Electrolyzer according to claim 6, characterized in that the gasket (4) comprises protrusions (5) and / or recesses (6) on both opposite sides. 8. The projections (14) and / or recesses (15) at the surface of the gasket (13) according to claim 7 are corresponding recesses (12) and / or projections (11) at the surface of the anode and cathode (10) adjacent thereto. Electrolyzer characterized in that the interaction with the field. The anode or cathode of claim 1 or 2, wherein the anode or cathode is disposed between the pair of gaskets (4, 7, 13, 16), the gaskets being at least of the gasket facing the anode or cathode (1, 10, 20). A protrusion 5, 8, 11, 14, 17 comprising a plurality of protrusions and / or recesses on one surface, the anode or cathode comprising recesses 12 on its surface, and one or both gaskets on the surface of both ) Pass through the recesses of the anode or cathode and also interact with corresponding recesses (6, 9, 12, 15, 18, 19) on the surface of the gasket on the opposite side of the anode or cathode. . 10. The electrolytic cell of claim 9, wherein the gasket is made of an elastic material. In a gasket of electrically insulating material suitable for electrolyzers, the gasket (4) has a corresponding recess (9) and / or protrusions (8) on its surface with the positive or negative electrode (1) or the gasket adjacent thereto. A gasket, characterized in that it comprises a plurality of protrusions (5) and / or recesses (6) adapted to interact. 12. The structure according to claim 11, wherein the gaskets (4, 7, 13, 16) have a planar frame structure having a space inside the frame that serves to form part of the anode or cathode (1, 10, 20) compartments. Characterized by a gasket.

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