SU111780A1 - Electrolyzer for alkalis - Google Patents

Description

Existing diaphragm electrolyzers for the production of alkalis, chlorine and hydrogen by electrolysis of alkali metal chloride solutions produce alkali with a significant admixture of chlorides, requiring evaporation in order to obtain concentrated alkalis.

In connection with the intensive development of the artificial fiber industry, which consumes a large amount of chlorine-poor caustic, the need for it cannot be satisfied by the production of caustic by the mercury method, and it is necessary to remove the caustic obtained from diaphragm electrolyzers from chlorides.

Attempts have been made to obtain alkalis poor in chlorine by electrolysis of alkali metal chloride solutions in electrolyzers with non-flowing membranes of ion exchange resins separating the anode and cathode spaces. However, due to the well-known Donnan equilibrium, non-flowing membranes, in principle, cannot have high selectivity, which inevitably leads to the penetration of hydroxyl ions from catholyte into the anolyte and a decrease in current yields of alkalis and hlssr.

The proposed electrolyzer is devoid of these disadvantages. The essence of the invention consists in accepting in the diaphragm electrolyzers an ion-exchange membrane between the diaphragm and the cathode with the release of an average electrodeless space. In this case, the hydroxyl ions penetrating through the membrane enter the middle, separated from the anolyte by the usual flow diaphragm, electrodeless space, in which the usual chlorine-rich electrolytic liquor is obtained, and alkali, almost free of chlords, is formed in the cathode space. At the same time, the alkali concentration in the cathode space, depending on the amount of water supplied from it, can reach the values obtained during caustic evaporation without affecting the anode process.

PA is a schematic representation of a section of a single cell of the proposed membrane-diaphragm electrolyzer for producing alkalis of the poor in chlorine, along with

electrolytic lye, chlorine and hydrogen.

A graphite anode 2 is introduced through the cover 3 (or the bottom) into the body / made of a corrosion-resistant insulating material. The anode space is separated from the middle electrodeless flow-through diaphragm 4. The middle space is separated from the cathode non-flowing ion exchange membrane 5. The steel wall 6 of the electrolyzer housing serves as the cathode. To discharge the electrolytic liquor containing chlorides, a drain tube 7 is installed in the middle electrodeless space, which ensures the maintenance of a constant level of liquor. For the supply of water to the cathode space and the withdrawal of alkali, poor in chlorine, there are valves 8 and 9; however, the output of alkali from the cathode space must ensure that the level is maintained at the same height as the level in the middle space. Part of the anolyte is discharged for saturation through shtutser 10. The cell is equipped with shtutsers not shown in

drawing, for the supply of anolyte and removal of chlorine from the anode space and hydrogen from the cathode space.

The cell shown in the drawing can be adapted for two-sided operation of the anodes and cathodes of the battery connection and have both a box and a cylindrical or comb configuration.

Subject invention

An electrolyzer for producing alkalis, chlorine and hydrogen by electrolysis of alkali metal chloride solutions, made with two-meter partitions separating the average electrodeless space from the anodic and cathodic, characterized in that, in order to obtain in the cathode space, an alkali poor in chlorine, while the interelectrode space of ordinary alkali, as the partition between the cathode and electrodeless space. we used an ion-exchange membrane.

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