Method and apparatus for producing sodium hypochlorite solution

Patent metadata

Field	Value
Publication number	US-2024279821-A1
Application number	US-202218563570-A
Country	US
Kind code	A1
Filing date	Mar 16, 2022
Priority date	May 31, 2021
Publication date	Aug 22, 2024
Grant date	—

Abstract

To provide a production method and a production apparatus of a sodium hypochlorite solution that can produce a sodium hypochlorite solution with a high available chlorine concentration at a low cost using an on-site facility. In production of a sodium hypochlorite solution by feeding secondary salt water as an aqueous sodium chloride solution, in an electrolyzer 10 comparted into an anode chamber 2 and a cathode chamber 3 by an ion-exchange membrane 1, to the anode chamber and, after electrolysis, introducing an anolyte and a generated chlorine gas in the anode chamber and an aqueous sodium hydroxide solution generated in the cathode chamber into a reaction tank 20 to allow the anolyte, the chlorine gas, and the generated aqueous sodium hydroxide solution as a catholyte to react in the reaction tank, a primary salt water generation step of dissolving raw salt G containing sodium chloride as a main component in purified water B to generate primary salt water, and a chelating step of chelating the primary salt water to generate secondary salt water A are included, in which a decomposition rate of salt ranges from 80 to 95%.

First claim

1 . A production method of a sodium hypochlorite solution, the method comprising,
in production of a sodium hypochlorite solution by feeding secondary salt water as an aqueous sodium chloride solution, in an electrolyzer comparted into an anode chamber and a cathode chamber by an ion-exchange membrane, to the anode chamber and, after electrolysis, introducing an anolyte and a generated chlorine gas in the anode chamber and a generated aqueous sodium hydroxide solution in the cathode chamber into a reaction tank to allow the anolyte, the chlorine gas, and the generated aqueous sodium hydroxide solution as a catholyte to react in the reaction tank, a primary salt water generation step of dissolving raw salt containing sodium chloride as a main component in purified water to generate primary salt water, and a chelating step of chelating the primary salt water to generate the secondary salt water, characterized in that a decomposition rate of salt ranges from 80 to 95%.

2 . The production method of a sodium hypochlorite solution according to claim 1 , wherein a bilayer membrane configured from a sulfonic acid layer and a carboxylic acid layer is used as the ion-exchange membrane.

3 . The production method of a sodium hypochlorite solution according to claim 1 , wherein a first switching means that switches whether or not the anolyte is introduced from the anode chamber into the reaction tank is provided between the anode chamber and the reaction tank to produce a sodium hypochlorite solution without introducing a part or the total amount of the anolyte into the reaction tank.

4 . The production method of a sodium hypochlorite solution according to claim 1 , wherein a second switching means that switches whether or not the chlorine gas is introduced from the anode chamber to the reaction tank is provided between the anode chamber and the reaction tank to perform production of a sodium hypochlorite solution with feeding of a part or the total amount of the chlorine gas to a facility where chlorine gas is used.

5 . The production method of a sodium hypochlorite solution according to claim 1 , wherein two or more of the electrolyzers are used to feed the chlorine gas obtained from one or more of the electrolyzers to a facility where chlorine gas is used, and a sodium hypochlorite solution is produced using the chlorine gas obtained from one or more of the electrolyzers.

6 . The production method of a sodium hypochlorite solution according to claim 1 , wherein purified water is introduced into the reaction tank to adjust a concentration of a sodium hypochlorite solution.

7 . The production method of a sodium hypochlorite solution according to claim 1 , wherein an available chlorine concentration of a sodium hypochlorite solution generated in the reaction tank is 8% or more.

8 . The production method of a sodium hypochlorite solution according to claim 1 , comprising a cation exchange step of treating raw material water with a cation-exchange resin to generate the purified water.

9 . The production method of a sodium hypochlorite solution according to claim 8 , wherein a water softener is used in the cation exchange step.

10 . The production method of a sodium hypochlorite solution according to claim 3 , wherein the first switching means is activated by a switching operation or an external signal based on an instruction from an automatic control apparatus communicable with the exterior of a production facility.

11 . The production method of a sodium hypochlorite solution according to claim 4 , wherein the second switching means is activated by a switching operation or an external signal based on an instruction from an automatic control apparatus communicable with the exterior of a production facility.

12 . The production method of a sodium hypochlorite solution according to claim 1 , wherein a sodium hypochlorite solution is produced on-site in the vicinity of a facility where a sodium hypochlorite solution is used.

13 . The production method of a sodium hypochlorite solution according to claim 1 , wherein an anolyte reservoir that reserves the anolyte and a catholyte reservoir that reserves the catholyte are provided in the vicinity of the electrolyzer, and bottoms of the anolyte reservoir and the catholyte reservoir are disposed above a position at half the height of the electrolyzer to respectively circulate the anolyte and the catholyte between the anolyte reservoir and the anode chamber and between the catholyte reservoir and the cathode chamber due to the difference in gravity.

14 . A production apparatus of a sodium hypochlorite solution, the apparatus being an apparatus comprising an electrolyzer comparted into an anode chamber and a cathode chamber by an ion-exchange membrane and supplied with secondary salt water as an aqueous sodium chloride solution, and a reaction tank into which products in the anode chamber and the cathode chamber after electrolysis are introduced, and producing a sodium hypochlorite solution by a reaction in the reaction tank, characterized in that
the apparatus comprises
a primary salt water generation section that dissolves raw salt containing sodium chloride as a main component in purified water to generate primary salt water, and
a chelating section that chelates the primary salt water to generate the secondary salt water, and
the apparatus is operated at a decomposition rate of salt ranging from 80 to 95%.

15 . The production apparatus of a sodium hypochlorite solution according to claim 14 , wherein the ion-exchange membrane is a bilayer membrane configured from a sulfonic acid layer and a carboxylic acid layer.

16 . The production apparatus of a sodium hypochlorite solution according to claim 14 , comprising a first switching means that switches whether or not the anolyte in the anode chamber is introduced from the anode chamber into the reaction tank between the anode chamber and the reaction tank.

17 . The production apparatus of a sodium hypochlorite solution according to claim 14 , comprising a second switching means that switches whether or not the chlorine gas generated in the anode chamber is introduced from the anode chamber into the reaction tank between the anode chamber and the reaction tank.

18 . The production apparatus of a sodium hypochlorite solution according to claim 14 , comprising two or more of the electrolyzers, and a chlorine gas feed path for feeding chlorine gas obtained from one or more of the electrolyzers to a facility where chlorine gas is used.

19 . The production apparatus of a sodium hypochlorite solution according to claim 14 , comprising a purified water introduction path for introducing purified water into the reaction tank.

20 . The production apparatus of a sodium hypochlorite solution according to claim 14 , for use in production of a sodium hypochlorite solution having an available chlorine concentration of 8% or more.

21 . The production apparatus of a sodium hypochlorite solution according to claim 14 , comprising a cation exchange treatment section that treats raw material water with a cation-exchange resin to generate the purified water.

22 . The production apparatus of a sodium hypochlorite solution according to claim 21 , wherein the cation exchange treatment section comprises a water softener.

23 . The production apparatus of a sodium hypochlorite solution according to claim 16 , wherein the first switching means is formed to be operable by a switching operati

Assignees

• De Nora Permelec Ltd

Inventors

• Domon Hiroki
• Sudo Shigeki
• Otsu Hideo

Classifications

• C25B15/02

  Process control or regulation · CPC title

• C25B13/08

  based on organic materials · CPC title

• C01B11/062

  Hypochlorites of alkali metals · CPC title

• C25B9/19

  with diaphragms · CPC title

• C25B15/087

  Recycling of electrolyte to electrochemical cell · CPC title