JPH0598485A - Apparatus having two or more electrolytic baths - Google Patents

Abstract

PURPOSE: To provide an apparatus capable of electrolyzing plural electrolytes in the same electrolytic cell chamber having plural electrolytic cells and producing plural electrolytic products in such same electrolytic cell chamber.

CONSTITUTION: This apparatus has two or more electrolytic cell groups, plural headers 12 to 21 capable of filling the electrolytic cells 1 to 10 of the different groups with the different electrolytes and plural headers capable of taking the different electrolytic products out of the electrolytic cells 1 to 10 of the different groups.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus having a plurality of electrolytic cells.

[0002]

BACKGROUND OF THE INVENTION Electrolytic cells are used to produce a wide variety of chemicals by electrolysis of suitable electrolytes. For example, although many electro-organic syntheses are carried out industrially, the original use of electrolytic cells for chemical production is in the electrolysis of aqueous alkali metal halides. Thus, such solutions have been electrolyzed on a very large scale worldwide to produce aqueous solutions of chlorine, hydrogen and caustic, for example aqueous sodium chloride solution to produce aqueous sodium hydroxide solution, chlorine and hydrogen. The aqueous potassium chloride solution is electrolyzed to produce an aqueous potassium hydroxide solution, chlorine and hydrogen. Such solutions have also been electrolyzed on a large scale to produce aqueous alkali metal chlorate solutions.

Although the electrolytic cell in which such electrolysis is performed is not divided in the electrolytic cell for producing alkali metal chlorate, it is generally separated from the adjacent cathode by a separator dividing the electrolytic cell into a plurality of anode chambers and a cathode chamber. It has a plurality of anodes and cathodes, with each anode separated. The anode chamber of such an electrolytic cell preferably has means for supplying the electrolytic solution to the electrolytic cell from one common header, and preferably means for removing the electrolytic product from the electrolytic cell via one or more common headers. I have it. Similarly, the cathode compartment of the electrolyzer is preferably provided with means for removing the electrolytic product from the electrolyzer via one or more common headers, and more preferably from the common headers to the electrolyzer with water or other fluid. Is optionally provided.

The electrolytic cell may be a diaphragm type or a membrane type.
In a diaphragm electrolyser, the separator positioned between adjacent anodes and cathodes is microporous so that, in use, the electrolyte passes through the diaphragm from the anode compartment of the electrolyser to the cathode compartment. In a membrane cell, the separator is essentially water impermeable and during use, ionic nuclei are transferred across the membrane from the anode compartment of the cell to the cathode compartment.

When an aqueous solution of an alkali metal chloride is electrolyzed in a diaphragm type electrolytic cell, the solution is suitably supplied from one common header to the anode chamber of the electrolytic cell, and chlorine produced by electrolysis is 1 The alkaline metal chloride aqueous solution is taken out from the anode chamber of the electrolytic cell through the common header of the book, the alkali metal chloride aqueous solution passes through the diaphragm, and the hydrogen and the alkali metal hydroxide produced by electrolysis pass through one or more headers and the cathode chamber. And the alkali metal hydroxide is taken out in the form of an aqueous solution of alkali metal chloride and alkali metal hydroxide.

When an aqueous solution of an alkali metal chloride is electrolyzed in a membrane type electrolytic cell, the solution is appropriately supplied from one common header to the anode chamber of the electrolytic cell, and chlorine produced by electrolysis and exhaustion are consumed. The alkali metal chloride solution thus obtained is taken out of the anode chamber through one or a plurality of headers, and alkali metal ions are supplied from a common header in which water or a dilute alkali metal hydroxide aqueous solution is supplied from a common header. The hydrogen and alkali metal hydroxide solution produced by the reaction of the alkali metal ions and water, transferred across the membrane to the cathode chamber, is removed from the cathode chamber via one or more headers.

The electrolyzer can have a large number of anodes and cathodes, especially if the electrolyzer is of the filter press type, and can include, for example, 50 or more anodes and cathodes. The electrolytic cell may also be monopolar or bipolar.
In a monopolar electrolyser, multiple anodes and cathodes are positioned in alternation, and when there is a separator, it is positioned between each anode and the adjacent cathode. The bipolar electrode is
It has a plurality of electrodes each having an anode surface and a cathode surface, and when a separator is present, it is positioned between the anode surface of one electrode and the cathode surface of an adjacent electrode.

In the operation of an electrolytic cell chamber having a plurality of such electrolytic cells, filling the electrolytic cell with electrolyte from a common source via one common header and electrolyzing via one or more common headers. The electrolytic product is removed from the bath. For example, in the electrolysis of an aqueous solution of an alkali metal chloride in a membrane-type electrolytic cell, the solution is generally filled from one common header into the anode chamber of each electrolytic cell, and water or an aqueous solution of an alkali metal hydroxide is fed into one common header. From the header will fill the cathode compartment of each electrolyser.

Similarly, electrolytically produced chlorine and depleted alkali metal chloride solutions are generally removed from the anode compartment of the electrolytic cell via one or more common headers,
The electrolytically produced hydrogen and aqueous alkali metal hydroxide solutions will generally be removed from the cathode chamber via one or more common headers for these products.

We have found that this conventional arrangement of electrolyzer compartments having multiple electrolyzers severely limits the flexibility of operation of such electrolyzer compartments. Therefore, in such an electrolytic cell chamber also having a plurality of electrolytic cells and a plurality of headers as described above, it is possible to electrolyze only one special electrolyte in the electrolytic cell of such an electrolytic cell chamber, which corresponds to it. It is possible to manufacture only one special product or one special product group. For example, in such an electrolytic cell chamber, an aqueous solution of sodium chloride or an aqueous solution of potassium chloride can be electrolyzed, and chlorine, hydrogen, an aqueous solution of sodium hydroxide or chlorine, hydrogen, an aqueous solution of potassium hydroxide can be produced correspondingly. .. In such an electrolyzer compartment, it is not possible to electrolyze both of the above-mentioned electrolytes at the same time, and neither of the above-mentioned product groups can be produced equally.

[0011]

We are able to electrolyze in a flexible manner with such an electrolytic cell chamber, in particular two or more electrolytes in the same electrolytic cell chamber having a plurality of electrolytic cells. It has also been determined that the desired purpose is to be able to operate in such a manner and in a manner such that two or more product groups can be produced in the same electrolyzer compartment having such multiple electrolyzers. The present invention provides a means by which this object is achieved and the flexibility of operation of such electrolyzer compartments can be greatly increased. In particular, the manner of operating such electrolyzer compartments can be rapidly changed due to the need to change the requirements for the various electrolytic products that can be produced in such electrolyzer compartments.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a plurality of electrolytic cells, a header for filling the electrolytic cells with electrolyte, one or more electrolytic products for removing one or more electrolytic products from the electrolytic cells. A device having an electrical circuit to which a header and an electrolyzer are connected, thereby supplying electric power to the electrolyzer, wherein the electrolyzers are arranged in two or more groups,
It is possible to provide an apparatus having a plurality of headers capable of filling different groups of electrolytic cells with different electrolytes and a plurality of headers capable of extracting different electrolytic products from different electrolytic cells of different groups.

The device can have a single electrical circuit to which several electrolyzers or even all electrolyzers belonging to different groups are connected. Of course, this is the conventional practice in an electrolytic cell chamber with multiple electrolytic cells. However, the novelty and inventive step of the present invention resides in the placement of multiple headers in the device.

In the conventional manner, the electrolyte is filled from a single common header into a group of all cells, so that a group of cells can always be used to electrolyze one electrolyte, for example sodium chloride. It can be used for electrolysis of aqueous solutions or aqueous solutions of potassium chloride, but both solutions are not electrolyzed in the electrolyzer of the group at the same time. However, in the device of the present invention having a plurality of headers for filling different specific electrolytes or specific electrolytic cell groups with different electrolytes, one type of electrolyte may be used in one electrolytic cell group and one or more It is possible to electrolyze another one type of electrolyte in the electrolytic cell group.

By connecting the electrolyzers to one suitable header, and by varying these connections as desired, different electrolyzers may be electrolyzed in multiple electrolyzer groups as the commercial requirements change. The proportion of electrolyte can be varied. If two or more different electrolytes are electrolyzed in multiple electrolyzers, it is of course necessary for the device to have a corresponding number of headers, filling different electrolyzers with different electrolyte products Will.

Although it is possible for two or more electrolytes to be electrolyzed in the apparatus at the same time, generally only two electrolytes are electrolyzed at the same time, ie the apparatus generally has two electrolyzer groups. Let's see As an example, the device will be described with respect to the simultaneous electrolysis of aqueous sodium chloride and potassium chloride solutions in the device.
In this case, the electrolytic cell would be connected to one electrical circuit and the device would have two headers. One of the headers can be filled with an aqueous sodium chloride solution in one cell group and the other header can be filled with an aqueous solution of potassium chloride in the other cell group.

Produced during electrolysis in both electrolyzer groups 1
Although chlorine and hydrogen may pass through one or more common headers for all electrolyzers when one or more electrolytic products, such as aqueous sodium chloride and potassium chloride solutions, are electrolyzed, the apparatus is It will have two headers, one that will pass the aqueous sodium hydroxide solution and the other that will pass the aqueous potassium hydroxide solution. By varying the number of electrolyzers in a group of electrolyzers connected to different headers, it is possible to significantly change the ratio of electrolyzed sodium chloride to potassium chloride in response to changing commercial requirements.

The electrolyzer of the device may have any structure, as the invention is not in the particular type of electrolyzer used in the device. For example, the electrolytic cell may be a monopolar type or a bipolar type, and between the anode and the adjacent cathode in the monopolar type electrolytic cell, the bipolar electrode of the bipolar type electrode may be used. It is also possible to mount a bipolar electrode cathode adjacent to the anode and a separator positioned between them.

The nature of the separator in the electrolytic cell, if present, depends on the nature of the electrolyte to be electrolyzed. The person skilled in the art will have no difficulty in choosing a suitable separator. Merely by way of example, when an aqueous alkali metal chloride solution is electrolyzed, a material suitable for use as a diaphragm is a sheet of asbestos or a microporous sheet of polymeric material such as polytetrafluoroethylene that is resistant to chemical action. However, other materials can be used including, for example, tetrafluoroethylene hexafluoropropylene copolymers, vinylidene fluoride polymers or copolymers and fluorinated ethylene propylene copolymers.

Materials suitable for use as ion exchange membranes when such materials are electrolyzed include anion exchange groups such as the sulfonic acid, carboxylic acid or phosphonic acid groups, their derivatives or two such groups. Or a fluorine-containing polymer material containing a mixture thereof. Suitable anion exchange membranes are described, for example, in British Patents 1,184,321, 1,402,920,
No. 1,406,673, No. 1,455,070, No. 1,497,748, No. 1,497,749, No. 1,518,387 and No. 1,531,068. It is a thing.

When an aqueous alkali metal chloride solution is electrolyzed, suitable materials for use as the anode are film-forming metals or alloys thereof, such as zirconium, niobium, tungsten, tantalum, with titanium being preferred and the surface of the anode being preferred. Is suitably coated with an electrocatalytically active conductive material. The coating is one or more platinum group metals, namely platinum, rhodium, iridium, ruthenium, osmium or palladium, and / or oxides of one or more of these metals.

The platinum group metal and / or oxide coating is
It can be present in admixture with one or more non-noble metal oxides, especially one or more film forming metal oxides such as titanium oxide. Electrocatalytically active conductive materials for use as anode coatings in electrolytic cells for the electrolysis of aqueous alkali metal chloride solutions and the use of such coatings are known in the art.

When the aqueous alkali metal chloride solution is electrolyzed, suitable materials for use as the cathode are iron, steel or nickel. The cathode can be coated with a material designed to reduce the hydrogen overpotential of electrolysis.

The electrolyzers of the electrolyzer group may be substantially the same. However, this is not always the case. For example, the properties of the separator of the electrolytic cell can vary depending on the properties of the electrolyte that is electrolyzed. Thus, if the electrolytic cells are equipped with ion exchange membranes, the membranes in those electrolytic cells in which sodium chloride is being electrolyzed are:
Although some electrolyzers can be used to electrolyze different electrolytes, it can be different than the ion exchange membrane in the electrolyser in which the aqueous potassium chloride solution is electrolyzed. The individual electrolyzers of the electrolyzer group are rapidly changed in response to changing manufacturing requirements, and in order to replace them with more suitable ones to meet the changing manufacturing requirements, It is preferable to provide means for immediately shorting the electrolysis cell from the electrical circuit, whereby the electrolysis cell is removed and replaced by another electrolysis cell. Further, to facilitate removal and replacement of the electrolytic cell, the electrolytic cell is preferably removed from the appropriate header and reattached to that header.

It is not necessary to replace the individual electrolyzers of an electrolyzer group according to changing manufacturing requirements. Therefore, when different electrolysis is performed in the same electrolysis cell, and all necessary when the electrolysis being performed changes, it is removed from one or more headers and mounted on another one or more headers. It is possible that it is for an electrolytic cell to be made. When the nature of the electrolyte is changed, it is also necessary to flush the cell prior to initiating electrolysis with the different electrolyte.

The apparatus of the present invention is simple in concept, but provides operational benefits, and in particular its use provides a plurality of electrolytic cells which are readily adaptable to changing manufacturing requirements. Thus, the device can, for example, immediately meet the increased demand for aqueous potassium hydroxide solution with the loss of aqueous sodium hydroxide solution, and vice versa.

The present invention will be described below with reference to the accompanying figures, which schematically show a device with a plurality of electrolytic cells. For purposes of explanation, the apparatus will be described with respect to an electrolytic cell group in which an aqueous solution of sodium chloride is electrolyzed and an electrolytic cell group in which an aqueous solution of potassium chloride is electrolyzed.

[0028]

EXAMPLE The apparatus has a plurality of monopolar electrolytic cells 1 to 10, each electrolytic cell having a plurality of anodes and cathodes, and each anode is
It is separated from the adjacent cathode by an anion exchange membrane which provides a plurality of anode and cathode chambers in each electrolyzer. Each electrolytic cell is connected to one common electric circuit.

The apparatus has a plurality of headers 12-21, the headers 12-17 being connected to the electrolyzer 1 by lines 22-27, respectively, and the electrolyzer 6 being lines 28-3.
3 connect to the headers 16-21 respectively.
The electrolyzers 2-5 are connected to the header in the same manner as electrolyzer 1, forming together with electrolyzer 1 a first electrolyzer group,
The electrolyzers 7-10 are connected to the header in the same way as the electrolyzer 6, and together with the electrolyzer 6 form a second electrolyzer group.

The headers 12 to 21 each have 12 N
Supply of aCl solution, 13 is return of exhausted NaCl solution, 1
4 is supply of NaOH solution, 15 is return of NaOH solution,
16 is a chlorine header, 17 is a hydrogen header, 18 is a KCl solution supply, 19 is a consumed KCl solution return, 20
Is for supplying the KOH solution, and 21 is for returning the KOH solution.

During operation, the NaCl aqueous solution and the dilute NaOH aqueous solution are filled from the headers 12 and 14 into the electrolytic cell 1 and the electrolytic cells 2 to 5 via the conduits 22 and 24, respectively, and the consumable NaCl aqueous solution, the NaOH aqueous solution, chlorine and Hydrogen is sent to the headers 13, 15, 16 and 17 via lines 23, 25, 26 and 27, respectively. The KCl aqueous solution and the dilute KOH aqueous solution are provided in the conduits 30 and 32, respectively.
Via the headers 18 and 20 to fill the electrolytic bath 6 and electrolytic baths 7 to 10, and the consumable KCl aqueous solution, KOH aqueous solution, chlorine and hydrogen are supplied to the pipelines 31, 33, 28, respectively.
It is sent to the headers 19, 21, 16 and 17 via 29. The device has only one chlorine header and one hydrogen header to which chlorine and hydrogen produced in both the first group of electrolytic cells 1 to 5 and the second group of electrolytic cells 6 to 10 are sent. Should be noted.

NaCl for electrolyzed KCl solution
It is necessary to change the ratio of the aqueous solution, for example to increase the ratio.
One or more electrolytic cells may be connected to the headers 12, 14, 13 and 15.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus having multiple electrolytic cells according to the present invention.

[Explanation of symbols]

 1-10 Single-pole type electrolyzer 11 Electric circuit 12-21 Header 22-23 Pipeline

Claims (6)

[Claims] 1. A plurality of electrolytic cells, one header for filling the electrolytic cell with an electrolyte, one or more headers for extracting one or more electrolytic products from the electrolytic cell, and an electrolytic cell are connected. In a device having a plurality of electrolyzers having an electric circuit for supplying electric power to the electrolyzers by means of the electrolyzers being arranged in two or more groups, said device filling different electrolyzers of different groups with different electrolytes. And a plurality of headers capable of removing different electrolytic products from different groups of electrolytic cells. 2. The apparatus of claim 1 having a plurality of electrolyzers arranged in two or more electrolyzer groups and a single electrical circuit to which all electrolyzers of the electrolyzer groups are connected. 3. The method according to claim 1, which has two electrolytic cell groups.
Or the device according to 2. 4. An apparatus according to any one of claims 1 to 3 having one or more common headers for taking one or more electrolytic products from the electrolytic cells of two or more electrolytic cell groups. .. 5. An apparatus according to claim 1, wherein the electrolysis cell is provided with means for short-circuiting the electrolysis cell immediately. 6. The method according to claim 1, which is used for electrolysis of an aqueous sodium chloride solution and an aqueous potassium chloride solution.
The apparatus according to paragraph.