A kind of alkali production process

Abstract

A production process of alkali, the steps are as follows: a. Secondary refined brine enters the anode chamber of the electrolytic cell through heat exchanger preheating. When the current reaches 5KA, acid is started to be added to the anode chamber. b. The chlorine gas produced by electrolysis passes through the heat exchanger to preheat the secondary refined brine, so that the temperature of the secondary refined brine reaches 55°C. c. Part of the 32±0.5% concentration of alkali discharged from the cathode chamber is mixed with an appropriate amount of pure water to make a 30±0.5% concentration of alkali into the cathode chamber, where hydrogen is electrolyzed in the cathode chamber. d. The temperature control of the electrolytic cell in the whole electrolytic reaction process is adjusted and controlled at 85-87° C. through the catholyte cooler. e. When the concentration of the electrode catholyte solution reaches 32±0.5%, it will be discharged from the cathode chamber. After passing through the catholyte cooler, part of it will be reused in the cathode chamber, and part will be output to the storage tank. The invention reduces the waste of energy, facilitates the rapid discharge of the generated gas, and improves the productivity of the alkali and the conductivity of the solution.

Description

technical field [0001] The invention relates to the field of chemical production, in particular to a production process of alkali. Background technique [0002] The chlor-alkali industry uses electrolysis of saturated NaCl solution to produce NaOH, Cl2 and H2, and uses them as raw materials to produce a series of chemical products. The chlor-alkali industry is one of the most basic chemical industries. Its products are not only used in the chemical industry itself, but also widely used in light industry, textile industry, metallurgical industry, petrochemical industry and public utilities. [0003] However, in the process of electrolyzing saturated NaCl solution in the chlor-alkali industry, since the unreacted hydroxide ions in the cathode chamber will gradually accumulate in the cathode chamber during the electrolysis process, it is possible to reverse osmosis through the cation exchange when a certain concentration is reached. The membrane enters the anode compartment. ...

AI Technical Summary

Problems solved by technology

[0003] However, in the process of electrolyzing saturated NaCl solution in the chlor-alkali industry, since the unreacted hydroxide ions in the cathode chamber will gradually accumulate in the cathode chamber during the electrolysis process, it is possible to reverse osmosis through the cation exchange when a certain concentration is reached. Membrane enters the anode compartment

Hydroxide ions are more likely to lose electrons than chloride ions in the case of electrolysis, and the chlorine gas produced is easy to react with hydroxide ions, and then the amount of chlorine gas produced in the anode chamber will decrease, and the sodium ions that pass through the cation exchange membrane will be reduced. The amount will be reduced accordingly, so the output of sodium hydroxide will be reduced

[0004] At the same time, the resistivity of the electrolyte will decrease with the rise of the solution temperature, so the anolyte often needs to be raised before entering the anode chamber, which will waste more energy

[0005] In addition, the chlorine gas produced is also relatively easy to dissolve in water or adhere to the surface of the anode electrode, which greatly reduces the conductivity of the anode.

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