RU2471891C2 - Electrolysis cell for producing chlorine - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: in an electrolysis cell for producing chlorine, bipolar electrode elements are made from a bimetallic sheet (steel+titanium); frames of bipolar chambers are made from shaped tubes; anode and bipolar chambers are made from a bimetallic sheet which is made by welding sheets with insert bimetallic (steel+titanium) elements; the anode and the cathode chambers are equipped with built-in heat exchangers, one part of which is formed by placing shortened metallic separating strips inside the chambers and hermetic sealing of the outer surface of the chambers with a metal sheet; the second part is formed by making supporting frames of the chambers hollow, which enables to use water cooling.

EFFECT: intense process of producing chlorine, easier and higher air-tightness of the electrolysis cell.

2 dwg

Description

The invention relates to the field of industrial production of chlorine, hydrogen and sodium hydroxide by electrochemical decomposition of a solution of sodium chloride and can be used to obtain chloragent for water disinfection stations.

Currently, electrolysis processes are widely used to solve the problems of various industries: in electrochemical production, nuclear fuel production, electronic engineering, non-ferrous metallurgy, engine manufacturing, pharmaceuticals, etc.

Each technical solution of the tasks by electrolysis of various materials and media also determines the design features of devices known by the same technical term - electrolyzer.

There are a large number of special-purpose electrolyzers with various distinctive features due to the solution of specific problems, which is confirmed, for example, by patents RU 2400566, RU 2404130, RU 2400861, RU 2405866, RU 2400975, RU 2406515, SU 770272 A1, etc.

Devices for electrochemical decomposition of sodium chloride solution and production of chlorine and production of a chlorinating agent for disinfecting water are taken as analogues of the proposed electrolyzer.

For example, in patent RU 2408541 C2 an electrolytic cell is described, which is a cylindrical electrolytic chamber made in the form of an insert in the main pipeline. This device, as well as the proposed one, can be used for disinfecting water, but it belongs to periodic electrolyzers and serves to implement a certain cleaning principle, which is acceptable for disinfecting only small volumes of water.

In addition, the use of this device requires compliance with special explosion safety standards and constant flushing, which complicates its operation.

Also known is an electrolyzer for producing chlorine and the concomitant production of alkali and hydrogen by electrolysis of a solution of sodium chloride, which can be considered a closer analogue of the invention (patent RU 2090519 C1). This electrolyzer contains a bipolar membrane filter and a separated anode and cathode chamber.

The use of an electrolyzer with separated anode and cathode chambers makes it possible to obtain a gaseous chlorinating agent in the anode chamber at relatively low energy consumption for electrolysis, which ensures the cost-effectiveness of the installation.

However, this installation has limited power and, as a result, a low yield of chlorine.

This disadvantage is eliminated in another known device, "Electrolyzer for chlorine and alkali" (SU 839310 Al).

This device contains a housing with two end monopolar electrodes of opposite polarity, between which are installed bipolar electrodes with anode and cathode elements, mounted on opposite sides of the carrier current distribution base.

Due to the fact that the housing of this device is equipped with one or more partitions made of non-conductive and impermeable to electrolyte material, located perpendicular to the bases of bipolar electrodes and hermetically separating the housing through the electrolyte into cavities connected by current, an increase in unit power is achieved.

However, this electrolyzer also has limited power and performance.

It is not possible to intensify the electrolysis process due to the fact that the cooling of the cathode and anode surfaces in this device occurs only in a natural way, and an increase in current loads and an increase in the temperature of the process to increase the productivity of the installation is possible only under the condition of additional and sufficient heat removal.

Closest to the proposed technical essence and the achieved result is an electrolyzer for producing gaseous chlorine, containing a support frame for electrode elements; bipolar electrode elements made of a bimetallic sheet (steel + titanium); anode and cathode chambers having a rectangular shape and including a power frame (patent RU 2281252 C2).

In the known prototype electrolyzer, the anode is formed by steel strips welded in the corners, the ends of which are protected by titanium on the anode side, and the partition is made of a bimetallic sheet (steel + titanium).

A feature of the anode element is that it is made in the form of a perforated or perforated sheet of titanium coated with ruthenium oxides and welded to the current-carrying edges of the anode chamber.

A feature of the cathode element is that it is a perforated or perforated sheet of carbon steel welded to the current-carrying ribs of the cathode chamber.

Due to the use of several bipolar electrode elements made of a bimetallic sheet obtained by tightening with fasteners, as well as the use of a sulfocationite membrane between them, stability of the electrochemical parameters of the process for a long time is ensured, as well as the safety of the process.

However, this electrolyzer as a device for the electrochemical decomposition of a solution of sodium chloride has the same significant disadvantages as the above analogues, namely:

- limiting the intensification of the process due to the impossibility of increasing current loads and increasing the temperature of the process, since above 70 degrees C, the polymer membrane decomposes,

- the presence of current losses and the possibility of leakage of electrolytes due to insufficient tightness of the connection of titanium and steel sheet in the manufacture of the anode,

- low efficiency of heat removal due to the natural air cooling of the surfaces of the cathode and anode.

In addition, the electrolyzer has a large weight and a large number of places for mechanical joining of metal elements (the possibility of corrosion or metal leaks), which reduces the operational characteristics of the electrolyzer.

The presence of these design flaws of the prototype device leads to a decrease in the efficiency and operation of the electrolyzer to produce chlorine in general.

The task of the invention is to increase the productivity of the cell and increase the convenience, reliability and safety of its operation.

The problem is solved in that in the electrolytic cell for chlorine production, equipped with support and clamping frames for electrode bipolar chambers made of bimetallic sheet (steel + titanium) and separated by a sulfocationite membrane; anode and cathode chambers having a rectangular shape and including power frames;

supporting and clamping frames for electrode bipolar chambers are made of profile pipes; anode and bipolar chambers are made of a bimetallic sheet obtained by welding sheets with inserted bimetallic (steel + titanium) elements;

the anode and cathode chambers are equipped with built-in heat exchangers, one of the parts of which is formed by placing shortened metal dividing strips inside the chambers and tightly covering the outer surface of the chambers with a metal sheet, and the second is formed by making the power frames of the chambers hollow.

New in the proposed design is that:

- the implementation of the electrode bipolar chambers, by welding sheets with inserted bimetallic (steel + titanium) elements, allows to increase the tightness of the bimetallic sheet compared to conventional bolted joints without changing the efficiency of current transfer.

- supplying the anode and cathode chambers with a built-in heat exchanger by placing shortened metal dividing strips inside the chambers and tightly covering the outer surface of the chambers with a metal sheet, as well as performing the hollow chambers power frame (from the profile pipe) allows to remove the heat load from the electrode surface due to the organized labyrinth movement of the coolant closed loop internal

- the use of water cooling not only allows you to increase the current load to intensify the process, but also improves the safety of operation of the electrolyzer, since the "water cushion" formed by the movement of the coolant along the internal closed loop is an additional means of preventing chlorine from entering the environment,

- the manufacture of support and clamping frames for electrode elements from shaped pipes allows to reduce the weight of the cell by 20-30% without compromising the reliability of the design, but greatly facilitates the installation of the device.

Thus, since the proposed design of the electrolyzer appears new properties, the proposed as an invention, the object has significant differences.

The proposed technical solution is new, since the totality of the claimed features for objects of the same purpose in the available sources of information has not been identified.

The scientific and technical level of the proposed solution is due to the results of theoretical calculations and experimental design work, as a result of which a device was created with improved production and operational characteristics, which allows not only to increase the yield of active chlorine and, accordingly, hydrogen and caustic soda, but also to increase the safety of operation of the electrolyzer .

Figure 1 presents the main structural elements of the electrolyzer, where:

1 - support frame

2 - clamping frame

3 - bipolar chamber

4 - anode chamber

5 - cathode chamber

6 - membrane

Figure 2 (side view) presents the structural elements of the anode and cathode chambers, where:

7 - heat exchanger

8 - dividing strips

9 - power frame

10 - metal sheet

The cell operates as follows.

In the lower unions of the anode chambers, a saline solution with a concentration of 300-320 g / dm ³ is prepared, prepared with softened water from salt (sodium chloride) "extra" according to GOST 13830. Softened water is supplied to the lower unions of the cathode chambers. A coolant (for example, circulating water) is introduced into the cathode and anode chambers into the labyrinth system of forced cooling formed by structural elements. An electric current is supplied to the electrolyzer through a thyristor current rectifier.

When current flows through an electrolyzer equipped with a support and clamping frame for electrode bipolar chambers made of a bimetallic sheet (steel + titanium) and separated by a sulfocationite membrane, the process of electrochemical decomposition of sodium chloride solution occurs, while chlorine is released on the anode and hydrogen on the cathode and alkali (caustic soda).

Schematic diagram of the production of chlorine is shown in figure 3.

The technical result of the implementation of the invention is the intensification of the process of producing chlorine, facilitating and increasing the tightness of the design of the cell.

Claims (1)

An electrolyzer for producing chlorine, equipped with a support and clamping frames for electrode bipolar chambers made of a bimetallic sheet (steel + titanium) and separated by a sulfocation-cationite membrane, containing an anode and cathode chambers having a rectangular shape and including power frames, characterized in that the supporting and clamping frames for electrode bipolar chambers are made of profile pipes; the anode and bipolar chambers are made of a bimetallic sheet obtained by welding sheets with inserted bimetallic (steel + titanium) elements; the anode and cathode chambers are equipped with built-in heat exchangers, one of the parts of which is formed by placing shortened metal dividing strips inside the chambers and tightly covering the outer surface of the chambers with a metal sheet, and the second is formed by making the power frames of the chambers hollow.

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