Process for producing alkali

Abstract

The invention relates to a process for producing alkali. The process comprises the following steps: a, secondary refined brine is preheated through a heat exchanger and enters an anode chamber of an electrolytic bath; when the current reaches 5KA, acid is added into the anode chamber; b, chlorine generated by electrolysis is used for preheating the secondary refined brine through the heat exchanger, so that the temperature of the secondary refined brine reaches 55 DEG C; c, part of alkali with the concentration being 32+/-0.5 percent exhausted from a cathode chamber is mixed with a moderate amount of pure water to generate alkali with the concentration being 30+/-0.5 percent, and the alkali with the concentration being 30+/-0.5 percent enters the cathode chamber and is electrolyzed in the cathode chamber to generate hydrogen; d, the temperature of the electrolytic bath in the whole electrolytic reaction process is regulated and controlled to 85-87 through a cathode liquor cooler; e, when the concentration of cathode liquor achieves 2+/-0.5 percent, the cathode liquor is exhausted from the cathode chamber; after the cathode liquor passes through the cathode liquor cooler, part of the cathode liquor is reused into the cathode chamber, and part of the cathode liquor is output to a storage tank. The process reduces energy waste, is beneficial to quickly exhausting the generated gas, increases the production rate of alkali, and improves the conductivity of liquor.

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 chamber. Hydr...

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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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