RU2614450C1 - Electrochemical module cell for treatment of electrolyte solutions - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: through two coaxial orifices are separated by three electrodes, which have a polarity at which the middle electrode is the counter electrode with respect to the outer and inner electrode, the outer electrode is the housing of the cell.

EFFECT: use of the invention allows more efficient use of space coaxially arranged cylindrical surfaces of the electrodes, thus enhancing productivity per unit volume of the reactor, to increase reliability and compactness of the cell facilitate the possibility of combining the electrochemical reactor cells in a higher productivity.

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Description

The invention relates to the field of chemical technology, in particular to devices for electrochemical processing of electrolyte solutions, and can be used in processes related to the electrochemical regulation of acid-base, redox properties and catalytic activity of water and / or aqueous solutions, as well as in processes obtaining various chemical products, in particular in the process of producing chlorine in the electrolysis of an aqueous solution of alkali or alkaline earth metal chlorides. The resulting chlorine can be used in technological processes, in the processes of purification and disinfection of water.

In applied electrochemistry, electrolyzers of various designs are used both for the treatment of water and / or aqueous solutions, and for the electrolytic production of various products, in particular flow electrolyzers with flat electrodes or electrolyzers with coaxially arranged cylindrical electrodes and a diaphragm between them.

The most promising are modular electrolyzers, which achieve the required performance by connecting the required number of electrochemical modular cells, which reduces the cost of designing and manufacturing electrolyzers of fixed capacity, unifies parts and assemblies, and reduces the time of installation and repair of such electrolyzers. For modular electrolyzers, the most significant is the design of the electrochemical cell, which determines all the advantages and disadvantages of a modular electrolyzer.

For example, an electrochemical modular cell [1] is known, for example, containing a main electrode mounted vertically, a cylindrical counter electrode also mounted vertically, a ceramic diaphragm placed coaxially with the main electrode and dividing the interelectrode space into sealed anode and cathode chambers, as well as lower and upper sealing devices for supplying processed fluids to the cathode and anode chambers and devices for removing liquids and gases from the anode and cathode chambers.

Also known electrochemical modular cell for the treatment of aqueous solutions [2]. The cell contains vertical coaxial cylindrical inner hollow and outer electrodes, lower and upper dielectric bushings, along the axis of which holes are made, and the input and output channels communicating with the camera of the external electrode are respectively displayed on the surface of the bushings. A zirconia-based ceramic diaphragm is made in the cell, coaxially mounted between the electrodes and dividing the interelectrode space into the electrode chambers. The inner hollow electrode is made with perforations. The inlet and outlet pipes of the chamber of the inner electrode are made of electrically conductive material and are equipped with devices for fastening and sealing the diaphragm.

A known installation for producing products of anodic oxidation of a solution of chlorides of alkali or alkaline earth metals [3]. The installation contains at least one electrochemical reactor made of 2-16 electrochemical cells, each of which contains a coaxially mounted inner cylindrical hollow anode and an outer cylindrical cathode and a diaphragm placed between them, made of ceramic based on zirconium, aluminum and yttrium oxides. The cathode and anode are installed in the lower and upper attachment points to form hydraulically closed anode and cathode chambers with an entrance at the lower attachment point and an exit at the top, while the input and output of the anode chamber communicate with the anode cavity. The anode is made with perforations. The anode and cathode are installed with an interelectrode distance (MER) of 8-10 mm, with d = 1.5-2.3 MER, D = 3.0-4.3 MER, L _d = 25-40 MER, δ = 0 , 15-0.35 MER and S _k ≥S _a , where d is the outer diameter of the anode, D is the inner diameter of the cathode, L _d is the length of the cathode, δ is the thickness of the side walls of the diaphragm, S _k is the cross-sectional area of the cathode chamber, S _a is the cross-sectional area of the anode chamber.

The disadvantages of the above-described modular cells include the inefficient use of the electrode surface, on which the main product is obtained, low coefficient of return on the volume of the working space and, as a result, low productivity. The lower the cell capacity, the greater the number of cells required to create an integrated reactor of a certain capacity. The more compounds, the lower the reliability of the reactor, additionally difficulties arise in ensuring uniform distribution of the flow of the electrolyte solution into the electrode chambers of the reactor cells. Operation of plants with such cells requires increased energy consumption.

Closest to the claimed invention is an electrochemical modular cell for processing solutions of electrolytes [4]. This cell contains a sealed housing with upper and lower covers, cylindrical, vertically mounted, outer and inner hollow electrodes coaxially arranged with respect to each other, and a microporous diaphragm located between the electrodes that separates the interelectrode space into the electrode chambers and forms a sealed chamber with the inner electrode. In this case, the electrodes and the diaphragm are placed in a sealed dielectric housing, and the outer electrode forms an untight chamber with the diaphragm. This solution, containing a pair of counter electrodes, allows to increase the productivity and reliability of the cell, and also provides uniform distribution of the electrolyte solution when combining the cells into a higher-capacity reactor. However, in a pair of counter electrodes, electrolysis passes only between the cylindrical surfaces of the electrodes facing each other, despite the fact that the surfaces opposite to them do not participate in electrolysis. Therefore, the use of only a pair of counter electrodes in flow cells limits the possibility of further increasing cell productivity.

The objective of the invention is to increase the performance of the electrochemical modular cell for processing solutions of electrolytes.

For this, the electrochemical modular cell for processing electrolyte solutions, as well as the cell of the prototype, contains a sealed housing in which there are cylindrical, vertically mounted, counter-coaxially arranged relative to each other electrodes separated from each other by means of a coaxial microporous diaphragm. The cell is characterized in that by means of two diaphragm coaxially arranged, three electrodes are separated from each other, having a polarity in which the middle electrode is a counter electrode with respect to the outer and inner electrodes, while the outer electrode is the cell body.

In the claimed design of the cell with three electrodes separated by two coaxial microporous diaphragms, two pairs of counter electrodes are formed: one electrode pair is formed between the inner surface of the outer electrode and the outer surface of the middle electrode, the second electrode pair is formed between the inner surface of the middle electrode and the outer surface internal electrode. Two diaphragms located between the three electrodes form four electrode chambers with them. Thus, in one case two two-chamber sub-cells are placed, doubling the productivity of the claimed cell. Since the amount of product released during electrolysis according to the Faraday law is directly proportional to the magnitude of the current flowing through the electrodes [5], due to the use of the outer surface of the middle electrode, its working area will increase by at least two times, which means that the conditions for maintaining an acceptable density will be met current on the electrodes. The polarity of the middle electrode is determined by the functional purpose of the cell. In the preparation of anode electrolysis gases, the middle electrode is preferably an anode. Using an external electrode as a cell body greatly simplifies the design while increasing productivity by at least two times while maintaining the same geometric dimensions.

The technical result achieved by the claimed invention is to increase the efficiency of using the area of the cylindrical surfaces of coaxially arranged electrodes, which allows to increase productivity from a unit volume of the reactor, to increase the reliability and compactness of the cell, and to simplify the possibility of combining electrochemical cells into a reactor with higher productivity.

The invention is illustrated by drawings, where in FIG. 1 shows a general sectional view of a cell; in FIG. 2 - section aa; in FIG. 3 is a bottom view.

An electrochemical modular cell for processing electrolyte solutions contains a sealed outer electrode 1 made of an electrically conductive material, which is the cell body. The cell body has nozzles 2 and 3, a top cover 4 made of dielectric material, with an outlet pipe 5 for removal of electrolysis products, a bottom cover 6 made of dielectric material, with an inlet pipe 7 for supplying the treated electrolyte solution. Inside the housing, a cylindrical inner hollow electrode 8, fixed by a pipe 9 with nuts 10 on the top cover 4 and a pipe 11 with nuts 12 on the bottom cover 6, as well as a middle electrode 13, mounted using current leads 14 and 15 on the bottom lid 6. Between the electrodes 8 and 13, a microporous diaphragm 16 is coaxially placed, hermetically fixed with sealing rings 17 in the lids 4 and 6, forming a sealed chamber 18 with the electrode 8. A micrometer is coaxially placed between the electrodes 1 and 13 a support diaphragm 19 sealed in the covers 4 and 6, forming a sealed chamber 20 with the outer electrode 1. The middle electrode 13 is made so that its upper and lower parts do not have tight contact with the covers 4 and 6. Due to this chamber 21, 22 formed between the middle electrode and the diaphragms are leaky.

The nozzles 9 and 11, mounted in the caps 4 and 6, serve to secure the internal electrode, supply and discharge of the treated solution to the sealed chamber 18 and can be connected to the electrode 8 by a threaded and / or welded joint. The electrode 8 has perforation holes 23 for supplying and discharging the processed electrolyte solution into the chamber of the internal electrode entering through the nozzles 9 and 11.

In a particular case, the outer electrode 1 may not have nozzles, then the supply and removal of the treated solution in the sealed chamber 20 is carried out through nozzles that are installed in the lids 4 and 6.

In a particular case, the electrode 8 may not have perforations, then the feed and discharge of the treated solution into the sealed chamber 18 is carried out through additional nozzles that are installed in the caps 4 and 6, and through the nozzles 9 and 11 a cooling agent can be supplied and discharged.

The operation of the cell is illustrated by an example of obtaining gaseous products of electrolysis, when the outer electrode 1 and inner electrode 8 are cathodes, and the middle electrode 13 is the anode.

The cell works as follows. Through the inlet pipes 3 and 11, the processed electrolyte solution enters the sealed chambers 18 and 20. Through the pipe 11, the solution enters the cavity of the cathode 8. Through the lower perforations 23, the solution enters the space between the diaphragm 16 and the outer surface of the cathode 8 and fills the sealed chamber 18. Through the upper perforation holes 23, the solution is discharged into the inner cavity of the cathode 8 and is removed from the cell through the pipe 9. The cathode chamber 20 is filled through the pipe 3, and the processed products are removed through the pipe 2. The electrolyte solution in the sealed chambers 18, 20 is circulated through an external circulation circuit. Through the pipe 7, the anode chambers 21 and 22 are filled. The pipe 5 is used to remove gaseous products of electrolysis. The required level of solution in the anode chambers 21, 22 is supported by external supply devices.

After applying voltage to the electrodes on the outer and inner surfaces of the anode 13, the release of electrolysis gases begins, which rise up and are discharged through the nozzle 5. Simultaneously, electromigration transfer of cations from the anode chambers through the diaphragms to the cathode chambers. When the cell is in flow mode, the treated solution with electrolysis products will be removed through the nozzle 5. When operating in the mode of receiving gaseous products, only electrolysis gas is removed through the nozzle 5.

To calculate the cell performance in comparison with the prototype, the geometric parameters of the prototype were used, provided that the middle electrode is an anode and the productivity was calculated using anode products.

In the prototype, the anode was made of VT1-0 titanium pipe with an outer diameter of 64 mm and an inner diameter of 60 mm. The height of the anode was 240 mm. The inner electrode was made of 12Kh18N10T pipe, the outer diameter of the cathode was 38 mm, and the height of the cathode was 240 mm. The interelectrode distance was 11 mm. Thus, the working area of the anode is 3.14 × 6 × 24 = 452 cm ² , with an allowable current density of 0.3 A / cm ² , the maximum allowable current will be 0.3 × 452 = 135.6 A. If the same anode use in the proposed solution, then its working area will be supplemented by using the outer surface and will be (3.14 × 64x24 = 482 cm2 + 452) = 934 cm ² , and the maximum allowable current is 0.3 × 934 = 280 A.

The claimed design allows to increase the productivity of the electrochemical cell for given products, to increase the reliability of the electrochemical cell in the production of aggressive gaseous electrolysis products, for example, chlorine-containing products, to simplify the possibility of combining electrochemical cells into a reactor with higher productivity, and also to expand the functionality of the cell by obtaining the target products as a mixture of gases or in the form of a solution.

Information sources

1. US 5635040, C02F 1/461, publ. 06/03/97;

2. RU 2176989, C02F 1/461, publ. 12/20/2001;

3. RU 2270885, С25В 1/46, publ. 02/27/2006;

4. RU 2581054, С25В 9/08, publ. 04/10/2016;

5. Antropov L.I. "Theoretical electrochemistry". M .: Higher school, 1984.

Claims (1)

An electrochemical modular cell for processing electrolyte solutions, containing a sealed enclosure in which are arranged cylindrical, vertically mounted, counter-coaxially disposed counter electrodes, separated from each other by a coaxial microporous diaphragm, characterized in that by two coaxially arranged diaphragms are separated from each other, three electrodes having a polarity in which the middle electrode is the counter electrode with respect to the outer and friction electrodes, wherein the outer electrode is the housing of the cell.

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