UDC 628.166:661.418
DOI 10.35776/VST.2024.02.07

FESENKO L. N., Pchel'nikov I. V., Ignatenko S. I., Skryabin A. Yu., Kaberskaia Dar’ia, Zaichko Dmitrii

Engineering-economic analysis and study of acid washing of electrolyzer cathodes with solutions of hydrochloric and sulfamic acids

Summary

Experience in operating electrolysis plants shows that the main problem with the reliability of their operation is associated with insoluble compounds – CaCO₃, CaSO₄, Mg (OH)₂ – buildup on the surface of the cathodes that cause abnormal electrolysis mode, overheating and warping of the electrode system, destruction of the oxide coating of the anodes, sudden reduction in the plant efficiency etc. The greatest effect on the liquid salts and gypsum buildup during the electrolysis of salt solutions is produced by the chemical composition of water that is associated with the presence of Ca²⁺, Mg²⁺, HCO^-₃, SO₄ and dissolved CO₂ ions. The method used in practice to remove carbonate deposits by regular washing the electrode system with 3–5% solution of hydrochloric acid is not always economically justified, particularly, for the water sources characterized by increased carbonate hardness. An engineering-economic comparison of two methods of acid washing of electrode plates of an electrolysis plant with solutions of hydrochloric and sulfamic acids while dissolving in them the accumulated buildup resulted from the preparation of sodium hypochlorite from a 3% solution of sodium chloride is presented. With a slightly higher cost of 1 liter of 5% sulfamic acid (6.9 rubles/l) compared to 5% hydrochloric acid (5.36 rubles/l), the cost of one washing with sulfamic acid (2.9 rubles) is 6 times higher than the cost of one washing with hydrochloric acid (0.48 rubles), which is associated with different possibilities for reusing acids for the next washing of the electrolysis plant. In other words, if 5% hydrochloric acid (HCl) can be used 11.1 times before its neutralization, then 5% sulfamic acid (NH₂SO₃H) can be used only 2.4 times, or 11.1/2.4 = 4.6 times less, which is illustrative of the obvious economic preference of hydrochloric acid over sulfamic acid.

Key words

water disinfection , membraneless electrolysis , acid-washing , low-concentrated sodium hypochlorite

For citation: Fesenko L. N., Pchel’nikov I. V., Ignatenko S. I., Skriabin A. Iu., Kaberskaia D. V., Zaichko D. A. Engineering-economic analysis and study of acid washing of electrolyzer cathodes with solutions of hydrochloric and sulfamic acids. Vodosnabzhenie i Sanitarnaia Tekhnika, 2024, no. 2, pp. 48–53. DOI: 10.35776/VST.2024.02.07. (In Russian).

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REFERENCES

1. Medrish G. L., Teimeva A. A., Basin D. L. Obezzarazhivanie prirodnykh i stochnykh vod s ispol’zovaniem elektroliza [Disinfection of natural and waste water with the use electrolysis. Moscow, Sproiizdat Publ., 1982, 81 p.].
2. Kurgaev E. F. Osvetliteli vody [Water clarifiers. Moscow, Sproiizdat Publ., 1977, 190 p.].