CN116947192A - Method and device for treating chlorine and oxychloride in dilute brine by chlorine-alkali electrolysis - Google Patents
Method and device for treating chlorine and oxychloride in dilute brine by chlorine-alkali electrolysis Download PDFInfo
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- 239000012267 brine Substances 0.000 title claims abstract description 215
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 title claims abstract description 215
- 239000000460 chlorine Substances 0.000 title claims abstract description 187
- 229910052801 chlorine Inorganic materials 0.000 title claims abstract description 125
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims abstract description 124
- 238000000034 method Methods 0.000 title claims abstract description 61
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 28
- 239000003513 alkali Substances 0.000 title claims abstract description 27
- RCJVRSBWZCNNQT-UHFFFAOYSA-N dichloridooxygen Chemical compound ClOCl RCJVRSBWZCNNQT-UHFFFAOYSA-N 0.000 title claims description 17
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical compound [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 claims abstract description 184
- 238000007323 disproportionation reaction Methods 0.000 claims abstract description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 49
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 46
- 239000007789 gas Substances 0.000 claims abstract description 44
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 28
- 230000002378 acidificating effect Effects 0.000 claims abstract description 21
- 150000003839 salts Chemical class 0.000 claims abstract description 21
- 239000011780 sodium chloride Substances 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 238000002360 preparation method Methods 0.000 claims abstract description 4
- 239000002918 waste heat Substances 0.000 claims abstract 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 74
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 63
- 239000012071 phase Substances 0.000 claims description 30
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 239000011734 sodium Substances 0.000 claims description 15
- 230000001105 regulatory effect Effects 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 12
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims description 10
- 229910052708 sodium Inorganic materials 0.000 claims description 9
- 230000003068 static effect Effects 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 230000000087 stabilizing effect Effects 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 239000007791 liquid phase Substances 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 5
- 239000012528 membrane Substances 0.000 claims description 4
- 230000033116 oxidation-reduction process Effects 0.000 claims description 4
- 230000001276 controlling effect Effects 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims 1
- 230000015572 biosynthetic process Effects 0.000 claims 1
- 125000001309 chloro group Chemical group Cl* 0.000 claims 1
- 238000012544 monitoring process Methods 0.000 claims 1
- 230000020477 pH reduction Effects 0.000 claims 1
- 238000000746 purification Methods 0.000 claims 1
- 235000010265 sodium sulphite Nutrition 0.000 claims 1
- 238000006298 dechlorination reaction Methods 0.000 abstract description 21
- 238000004064 recycling Methods 0.000 abstract description 5
- 239000006227 byproduct Substances 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 238000001704 evaporation Methods 0.000 abstract description 3
- 230000008020 evaporation Effects 0.000 abstract description 3
- 230000018044 dehydration Effects 0.000 abstract description 2
- 238000006297 dehydration reaction Methods 0.000 abstract description 2
- 238000011161 development Methods 0.000 abstract description 2
- 238000004134 energy conservation Methods 0.000 abstract description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract 2
- 230000007613 environmental effect Effects 0.000 abstract 2
- 239000012141 concentrate Substances 0.000 abstract 1
- 239000002699 waste material Substances 0.000 abstract 1
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 30
- 235000002639 sodium chloride Nutrition 0.000 description 23
- 238000006722 reduction reaction Methods 0.000 description 20
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 19
- 235000011121 sodium hydroxide Nutrition 0.000 description 18
- 238000010521 absorption reaction Methods 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 7
- 230000036632 reaction speed Effects 0.000 description 6
- 238000005070 sampling Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- QBWCMBCROVPCKQ-UHFFFAOYSA-N chlorous acid Chemical compound OCl=O QBWCMBCROVPCKQ-UHFFFAOYSA-N 0.000 description 1
- 229940077239 chlorous acid Drugs 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000026045 iodination Effects 0.000 description 1
- 238000006192 iodination reaction Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000012946 outsourcing Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/70—Treatment of water, waste water, or sewage by reduction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/24—Halogens or compounds thereof
- C25B1/26—Chlorine; Compounds thereof
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
- C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
- C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention produces the active chlorine (Cl) in the electrolyzed light brine and the chlorine water 2 、ClO ‑ ) Disproportionation to chlorate (ClO) under weakly acidic conditions 3 ‑ ) With ClO as byproduct of electrolysis 3 ‑ Concentrated to a novel chlorate full decomposition (gas phase containing) device, organically combines disproportionation and decomposition and concentrates the disproportionation and the decomposition backCollecting NaCl and Cl 2 、H 2 O, creating a new dilute brine treatment device, and simultaneously providing two methods for recycling the waste heat of the electrolyzed dilute brine, namely disproportionating and heating the brine, and disproportionating and preparing alkali by halogenated salt at the same time when concentrating the dilute brine. The invention adopts the national policy of low carbon, energy conservation and environmental protection, and is used for eliminating the lagging process of energy waste such as the dechlorination of the light brine chlorine water, the salt preparation by evaporation of the well and mine brine, the addition of water-soluble salt to alkali, the dechlorination and the dehydration of brine, the return of the light brine after dechlorination to the mine-soluble salt and the like, so as to promote the development of the chlor-alkali industry to the low carbon, environmental protection and sustainability.
Description
Technical Field
The invention relates to a method for treating chlorine and oxychloride in chlor-alkali discharged electrolysis dilute brine and a device thereof, belonging to the field of chlor-alkali industrial brine electrolysis production technology (NaOH and KOH production), in particular to a method for dissolving refined brine into dilute brine and discharging a byproduct chlorine in an anode chamber after electrolysis of the refined brineOxychlorides (ClO) 3 - 、ClO - 、Cl 2 ) The technology of thoroughly removing the dilute brine from the discharge tank has the quality percent of pass of residual chlorine of the treated dilute brine of 100 percent, does not lose the heat energy released by electrolysis carried by the dilute brine, and efficiently and energy-effectively circularly and re-dissolves salt to produce caustic soda.
Background
The conventional electrolytic light brine dechlorination process refers to the figure 2
Adding acid into dilute brine at the temperature of minus 87 ℃ to adjust the pH value to 2+/-0.5, then adding the dilute brine into a dechlorination tower, keeping the absolute pressure in the dechlorination tower to about 33.3kpa under the suction of a vacuum pump, enabling most of chlorine in the dilute brine in the dechlorination tower to escape from liquid phase flash evaporation, cooling to below 40 ℃ in a cooler, separating wet chlorine from chlorine water, condensing part of chlorine into chlorine water, recycling the chlorine water into a chlorine water tank, recycling the chlorine water condensed by a wet chlorine main pipe into the chlorine water tank, circularly heating to 90 ℃, feeding the chlorine gas into the dechlorination tower again to dechlorinate, pumping the chlorine gas which is not condensed by the cooler into a water ring type vacuum pump, cooling and separating the wet chlorine gas into a wet chlorine main pipe, using the chlorine water for working fluid of a water ring type vacuum pump, intensively collecting the redundant chlorine water dechlorination water tank, adding caustic soda into the dilute brine containing a small amount of active chlorine in the dechlorination tower to adjust the pH value to 9-11, and adding Na with the concentration of 5% -10% of liquid 2 SO 3 Reduction to Cl - Eliminating residual active chlorine; the chemical equation is as follows:
Na 2 SO 3 +Cl 2 +2NaOH＝Na 2 SO 4 +2NaCl+H 2 O
after chemical reduction of residual active chlorine, the light brine is desaturated with NaCl, na 2 SO 4 Is removed by a denitration procedure.
Outsourcing solid Na 2 SO 3 Manually adding the mixture into a preparation tank, adding water, heating to dissolve the mixture into liquid, and concentrating 5 to 10 percent of Na 2 SO 3 And (3) adding the residual active chlorine into the dilute brine under the control of a control valve by using a centrifugal pump, and controlling the oxidation-reduction potential of the dilute brine to be qualified from-500 mv to +500 mv.
Running state of chlorate decomposition process in fresh brine
And (3) separating out a part of the electrolyzed dilute brine from the vacuum dechlorination header pipe, proportioning the chlorate content in the electrolyzed dilute brine with high-purity hydrochloric acid (31% HCl), then adding the mixture into a chlorate decomposition tank, heating steam, adding the heated steam to raise the temperature to between 90 and 95 ℃, decomposing the chlorate in the dilute brine, removing harmful absorption after diluting the gas phase part by process air, and emptying the components insoluble in alkaline liquid. The liquid phase part overflows after full reaction to be recycled and enters a light salt water main pipe, and then enters a dechlorination tower to remove residual chlorine. Control of NaClO in chlorate decomposition completion liquor 3 2-3 g/L, HCl-25 g/L, and the decomposition temperature is controlled between T=90-95 ℃. The chlorate decomposition technology is only partial decomposition and not complete decomposition (including gas phase), and the technological principle clearly shows that complete chlorate decomposition (including gas phase) is impossible, and a great amount of ClO which is not completely decomposed exists in the gas phase 2 Is reasonable, and the theoretical basis only supports incomplete decomposition. The decomposition of the liquid phase is not thorough, and a certain amount of chlorate still remains in the chlorate decomposition completion liquid.
Disclosure of Invention
The technical task of the invention is to add chlorine and oxychloride (ClO) in the dilute brine which is a byproduct of the electrolytic anode chamber 3 - 、ClO - 、Cl 2 ) Thoroughly eliminates the residual chlorine in the neutral environment to be zero, and the decomposed gas phase product is pure and easy to recycle. 1 basic idea of the invention for accomplishing the above tasks
The correctness of the electrochemical theory basis on which the design of the industrial device of the innovative technology is based is proved from the electrochemical reaction mechanism of chlorine and oxychloride.
1.1 complete decomposition of chlorate in light brine (gas phase)
Under the strong acid working condition environment (T=298 k, [ H ] + ]=1 mol/L, standard electrode potential) electrode potential map as shown in fig. 1, in which the redox standard electrode potential associated with chlorate decomposition:
E A θ ClO 3 - /ClO 2 ＝1.75V, E A θ ClO 2 /HClO 2 ＝1.188V,
E A θ ClO 3 - /Cl 2 ＝1.468V, E A θ ClO 3 - /HClO 2 ＝1.181V,
E A θ HClO 2 /Cl 2 ＝1.659V, E A θ HClO 2 /HClO＝1.701V,
E A θ HClO/Cl 2 ＝1.630V。 E A θ Cl 2 /Cl - ＝1.35828V
from the pair of standard electrode potentials in fig. 1, it is known that:
(E A θ ClO 2 /HClO 2 ＝1.188V)-(E A θ Cl 2 /Cl - = 1.35828V) = -0.17028v→reaction to the left
(E A θ ClO 3 - /HClO 2 ＝1.181V)-(E A θ Cl 2 /Cl - = 1.35828V) = -0.17728v→reaction to the left
(E A θ ClO 3 - /ClO 2 ＝1.75V)-(E A θ Cl 2 /Cl - = 1.35828V) = 0.39172v→reaction to the right
(E A θ ClO 3 - /Cl 2 ＝1.468V)-(E A θ Cl 2 /Cl - = 1.35828V) = 0.1097v→reaction to the right, i.e.:
NaClO 3 +2HCl＝NaCl+ClO 2 +1/2Cl 2 +H 2 O (1)
NaClO 3 +6HCl＝NaCl+3Cl 2 +3H 2 O (2)
and, in contrast,
ClO 2 +HCl≠HClO 2 +1/2Cl 2
the method is also a recognized chlorate decomposition process principle in the chlor-alkali community since the generation of the ionic membrane electrolysis process, is the only theoretical basis of all equipment, process configuration, process control indexes and operation methods, but does not reach the ultimate goal of chlorate decomposition in the dilute brine, and a chlorate decomposition unit is also used until nowDoes not solve the problem that a large amount of ClO is always present in the chlorate decomposition gas-phase product 2 The chlorate decomposition is not complete and other more excellent dilute brine treatment techniques cannot be employed on chlor-alkali plants.
The problem can be completely solved from another thinking point of view, and the electrode potential pair difference can be changed under the nonstandard state. Will [ H ] + ]Lifting to [ H ] in the working condition environment of 0.5-1.5 mol/L dilute hydrochloric acid + ]About 10mol/L, T=298K. Wherein E is A θ ClO 2 /HClO 2 ＝1.188V,E A θ Cl 2 /Cl - ＝1.35828V；
Oxidation side: cl - -e＝1/2Cl 2 ，
E A Cl 2 /Cl - ＝1.35828+0.0592/2*lg(1/10 2 )V＝1.29908V；
Reduction side: clO (ClO) 2 +H + +e＝HClO 2 ，
E A ClO 2 /HClO 2 ＝1.188+0.0592/1*lg(10/0.01)V＝1.3656V；
Electrode potential pair difference:
(E A ClO 2 /HClO 2 ＝1.3656V)-(E A Cl 2 /Cl - ＝1.29908V)＝0.06652V；
this redox reaction proceeds to the right.
ClO 2 +HCl＝HClO 2 +1/2Cl 2 (3)。
In fact, HClO 2 Is extremely unstable in a strongly acidic solution,
chlorous acid reduction electrode potential contrast:
(E A θ HClO 2 /Cl 2 ＝1.659V)-(E A θ Cl 2 /Cl - ＝1.35828V)＝0.30072V,
the chemical reaction equation:
HClO 2 +3HCl＝2Cl 2 +2H 2 O(4)。
nascent HClO 2 In the presence of concentrated hydrochloric acid31% hcl) is easily quenched with high concentration of Cl - Reduction to Cl 2 ，Cl - Itself is also oxidized to Cl 2 。ClO 2 Reduction to HClO 2 Dissolving in concentrated hydrochloric acid, and gas phase HClO 2 Occupy ClO 2 The ratio of (2) is very low in a concentrated hydrochloric acid environment, and 1% is only very conservative data.
The whole decomposition process of chlorate in light brine (containing gas phase) is as follows:
under the working condition of the dilute hydrochloric acid,
NaClO 3 +2HCl＝NaCl+ClO 2 +1/2Cl 2 +H 2 o and NaClO 3 +6HCl＝NaCl+3Cl 2 +3H 2 O
Under the working condition of the concentrated hydrochloric acid,
ClO 2 +HCl＝HClO 2 +1/2Cl 2 and HClO 2 +3HCl＝2Cl 2 +2H 2 O
Finally, the chlorate in the light brine is decomposed completely (gas-containing liquid phase)
NaClO 3 +6HCl＝NaCl+3Cl 2 +3H 2 O
Theoretically, clO in the gas phase after chlorate decomposition 2 Further reduced and subdivided into Cl in concentrated hydrochloric acid environment 2 It has been demonstrated that it is now the basis for innovative processes for the total decomposition (gas phase) of its corresponding chlorate.
1.2 active chlorine (Cl) in light brine 2 、ClO - ) Disproportionation of (a)
Under the weak acidic working condition (t=333k, ph=3 to 7), the chemical equation of the disproportionation reaction of active chlorine in the dilute brine:
2HClO≒HClO 2 +HCl(5)
HClO 2 +NaClO＝NaClO 3 +HCl (6)
2HClO+NaClO≒NaClO 3 +2HCl(7)
in the disproportionation of active chlorine, the product HClO of formula (5) 2 The molecular state is bimolecular reversible reaction, the reaction speed depends on the equilibrium constant among molecules, and the temperature rise can promote the potential difference and the molecular activity of the disproportionation reaction and accelerate the disproportionation reaction to reach the equilibrium concentration. WhileThe disproportionation product of formula (6) is ClO 3 - 、Cl - Are all fully ionized anions and the reaction is completed rapidly.
As can be seen from the above chemical reaction equation, clO in particular is based on complete decomposition of chlorate 2 After complete decomposition, the disproportionation (chemical) method is just to eliminate active chlorine (Cl) 2 、ClO - ) The simplest method. Under the working condition of stable pH, only the temperature is a factor influencing the reaction speed, and the equilibrium constant of the reversible reaction of the formula (5) is determined, the reaction speed is lower at normal temperature, and whether the reaction speed at the electric tank temperature (87 ℃) is proper or not is determined by experimental data.
2 experimental evidence derived from the theory above
2.1 Total chlorate decomposition (gas phase containing) pilot plant
The chlorate in the dilute brine is decomposed in the environment of dilute hydrochloric acid (HCL 0.5-1.5 mol/L) and industrialized, and the experiment proves that the chlorate is not involved any more and only the second step of concentrated hydrochloric acid absorption of ClO is required to be confirmed 2 The reaction conditions, i.e. the reaction rate at a suitable reaction temperature, make up the whole chlorate decomposition process. When absorbing ClO in gas phase 2 The hydrochloric acid concentration is commercial grade concentration [ HCl ]]when=10mol/L, clO 2 Can be completely dissolved in concentrated hydrochloric acid, and the reaction time and temperature for complete absorption are the optimal choice.
In the small test scheme, a gas phase pipeline sampling port after the chlorate decomposition tank in normal operation is connected with a gas conduit, a gas flowmeter (3000 mL/h) is connected behind the gas conduit, three absorption bottles (1000 mL) are connected in series, 800mL of 45 ℃ concentrated hydrochloric acid (31% HCl) is added into the three absorption bottles, an outlet is connected with a draught fan, a glass tube of the absorption bottle (1000 mL) containing 800mL of 15% NaOH absorption liquid is connected with an outlet of the draught fan and inserted into the bottom, and the glass tube is arranged on the bottle plug for exhausting. Opening a sampling valve at a sampling port of the gas phase pipeline, starting a fan to suck mixed gas at a speed of 2L/h, purifying and absorbing ClO by concentrated hydrochloric acid 2 Then absorbing chlorine gas by 15% NaOH, respectively sampling from 15% caustic soda absorbing bottle solution after 30min and 60min, and analyzing NaClO 3 And NaClO.
The analysis results all show that the 15% caustic soda absorption bottle solution only containsNaOH and NaClO, and NaClO 3 Not detected.
The experiment was repeated 20 times according to the above protocol and the results were completely consistent.
Conclusion: only qualitative analysis of this pilot run has demonstrated ClO 2 Is completely absorbed by 45 ℃ concentrated hydrochloric acid (31 percent HCl) and reduced into Cl 2
2.2 Experimental proposal of active chlorine disproportionation technique on chlor-alkali industrialization device
The reactive chlorine is eliminated at normal temperature at a slower reaction speed, the reaction speed is only confirmed at the normal running tank temperature (87+/-3 ℃) of the electric tank, the residual chlorine after reversible reaction is within the allowable range within the allowable reaction time, and the residual chlorine after concentration of the dilute brine is tested.
(1) Experimental scheme on chlor-alkali industrialization device
Split 10m on a brine header to a dechlorination unit 3 The pH value of the dilute brine of/h is measured to be 4.1, the dilute brine is heated to 90 ℃ at steady temperature, and the sample is taken to analyze active chlorine (HClO, clO) - )、NaClO 3 Is sent to a disproportionation reactor for reaction, and the liquid level of the reactor is controlled to be 10m 3 (60min)、20m 3 (120min)、30m 3 (180 min), adding 10% Na into dilute brine at 90 ℃ below zero after disproportionation reaction 2 SO 3 And (3) recovering the brine after reducing the residual chlorine. In addition, 250mL of the sample was taken from the dilute brine outlet of the disproportionation reactor at the time of 120min of disproportionation, and concentrated to 190 to 200mL.
Sampling from dilute brine outlet of disproportionation reactor, cooling to normal temperature, and analyzing active chlorine (HClO, clO) - )、NaClO 3 The method comprises the steps of carrying out a first treatment on the surface of the Taking three analysis samples in each time period, and recording analysis results as an average value;
the pH value of the light salt water is adjusted to pH 5+/-0.2 by the operation method, and the active chlorine (HClO, clO) is analyzed - )、NaClO 3 ；
The pH value of the light salt water is adjusted to pH 6+/-0.2 by the operation method, and the active chlorine (HClO, clO) is analyzed - )、NaClO 3 ；
Concentrating 250mL of light brine to 190-200 mL, and analyzing the pH value, naCl and active chlorine (HClO, clO) of the light brine - )、NaClO 3 。
The method for analyzing the active chlorine comprises the following steps: iodination.
The experiment was repeated 20 times according to the above protocol and the results were completely consistent.
(2) Experimental results
(3) Conclusion: under the normal operation temperature of the electrolytic tank, the active chlorine (ClO) contained in the electrolyzed dilute brine is obtained through constant temperature disproportionation for 180min - 、Cl 2 ) The method is enough to reduce the process index which reflects the economic value of the innovative technology. The dilute brine disproportionation concentration device is adopted, and the process index of residual chlorine in the concentrated brine is better.
The invention eliminates chlorine and oxychloride (ClO) in the dilute brine 3 - 、ClO - 、Cl 2 ) The adopted technical proposal
Chlorate in light brine (ClO) 3 - ) Full decomposition (gas phase containing) apparatus (see fig. 3): comprises a hydrochloric acid heater and ClO 2 The reduction tower, the chlorate decomposer and the connecting pipeline thereof are characterized in that the process parameter measuring instrument comprises a thermometer, a manometer, a liquid level display, a flowmeter and an automatic control valve for controlling process parameters.
The specific technical process comprises the following steps: heating high-purity hydrochloric acid provided outside the boundary region to 25-60 ℃, and metering ClO according to the chlorate content ratio in the light brine 2 A reduction tower, which is provided with a hydrochloric acid regulating valve to control the flow and decompose ClO from the chlorate decomposer 2 And Cl 2 The mixed gas is in countercurrent contact in a tower, clO 2 Is absorbed and reduced into Cl 2 And discharging the gas from the gas phase outlet of the reduction tower and merging into a chlorine gas main pipe. Reduction of ClO 2 The concentration of the concentrated hydrochloric acid is reduced to some extent, and the concentrated hydrochloric acid is added into the dilute brine from electrolysis, and the mixture is evenly mixed and then is added into a chlorate decomposer, and the chlorate decomposer is preheated, heated, decomposed and cooledAnd (3) decomposing chlorate in the dilute brine after separation, merging gas phase parts, treating the gas phase parts in a reduction tower, and acidifying the decomposed acidic dilute brine into and out of the brine in an electrolytic tank under the control of an automatic regulating valve to neutralize NaOH reversely transferred by an ionic membrane in a cathode chamber of the electrolytic tank.
Active chlorine (ClO) in light brine - 、Cl 2 ) Disproportionation device (refer to fig. 4): the device comprises a static mixer, a heater, a disproportionation reaction tank, a brine heat exchanger and a set of chlorate decomposition device, wherein a branch pipe chlorate decomposition device is arranged on a fresh brine main pipe, a 32% NaOH adding pipeline and an automatic regulating valve are arranged on the fresh brine main pipe, the acidified chlorine water from a chlorine water tank is connected to the fresh brine main pipe before the static mixer, the devices are connected through pipelines, a measuring instrument comprises a thermometer and a pH detector, the thermometer and the pH detector are arranged on a connecting pipeline, and 5-15% Na is arranged on the connecting pipeline 2 SO 3 Adding a pipeline and an automatic regulating valve to the disproportionated dilute brine main pipe, and measuring and providing process parameters by an oxidation-reduction potentiometer on the dilute brine main pipe to control 5-15% of Na 2 SO 3 The addition amount is as follows.
The specific technical process comprises the following steps: the dilute brine from the electrolytic outlet tank is fed into a dilute brine main pipe, 32% NaOH and acidified chlorine water are added under the control of an automatic regulating valve, fully mixed by a static mixer, fed into a steam heater to control the temperature of the dilute brine to be between 84 and 90 ℃ and the pH value to be between 5 and 6, fed into a disproportionation reactor, and active chlorine (ClO) - 、Cl 2 ) Disambiguation to ClO 3 - The residual chlorine is dissolved in the light salt water and discharged together, and then 5 to 15 percent of Na is added 2 SO 3 The addition amount is reduced to active chlorine (ClO) - 、Cl 2 ) The temperature of the primary refined brine is raised to be more than 65 ℃ to be refined for the second time, then electrolysis is carried out, and the temperature of the-55 ℃ light brine is subjected to denitration or salinization. And (3) discharging the electrolyzed dilute brine into a chlorate decomposition device from a branch pipe on the main pipe, decomposing chlorate in the dilute brine, recycling chlorine to the main pipe, and acidifying the decomposed acidic dilute brine to enter and exit the electrobath brine and condensing chlorine water from wet chlorine gas of chlorine hydrogen treatment.
Chloride-containing dilute brine (ClO) - 、Cl 2 ) Disproportionation concentration device(refer to fig. 5) includes: active chlorine (ClO) in light brine - 、Cl 2 ) The disproportionation device is composed of a set of general dilute brine concentration device.
The specific technical process comprises the following steps: the disproportionated light brine is directly subjected to light brine concentration by a light brine concentration device (the light brine concentration device is a known technology) and is concentrated into concentrated brine (NaCl is more than or equal to 225 g/L), the concentrated brine is subjected to denitration or salt dissolution, and the denitration concentrated brine and the primary refined brine are mixed according to the proportion and then subjected to secondary refining and electrolysis.
Drawings
FIG. 1 Standard electrode potential diagram of chlorine element between different valence levels
FIG. 2 vacuum dechlorination of dilute brine (containing ClO) 3 - Decomposition) process flow diagram
The reference numerals in fig. 2 denote: 1Na 2 SO 3 Preparation tank 2 dechlorination tower 3 chlorine cooler 4 vacuum unit 5 chlorine water tank 6 chlorate decomposer
FIG. 3 is a schematic flow chart of a complete chlorate decomposition (gas phase containing) process
The reference numerals in fig. 3 denote: 1 hydrochloric acid heater 2ClO 2 Reduction tower 3 chlorate decomposer
FIG. 4 active chlorine (ClO) in light brine - 、Cl 2 ) Disproportionation process flow diagram
The reference numerals in fig. 4 denote: 1 temperature stabilizing heater 2 disproportionation reactor 3 brine heater 4 heater 5ClO 2 Reduction tower 6 chlorate decomposer
FIG. 5 is a flow chart of a process for disproportionation and concentration of dilute brine
The reference numerals in fig. 5 denote: 1 Heater 2ClO 2 Salt water mixer of reduction tower 3 chlorate decomposer 4 temperature stabilizing heater 5 disproportionation reactor 6 concentration unit 7 denitration unit 8
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Example 1
Referring to FIG. 3, the present invention provides chlorate (ClO) 3 - ) A total decomposition (gas phase-containing) device;
the implementation process is as follows: the specific technical process comprises the following steps: heating high-purity hydrochloric acid provided outside the boundary region to 25-60 ℃, and metering ClO according to the chlorate content ratio in the light brine 2 A reduction tower, which is provided with a hydrochloric acid regulating valve to control the flow and decompose ClO from the chlorate decomposer 2 And Cl 2 The mixed gas is in countercurrent contact in a tower, clO 2 Is absorbed and reduced into Cl 2 And discharging the mixture from the outlet of the reduction tower and merging into a chlorine main pipe. Reduction of ClO 2 The concentration of the concentrated hydrochloric acid is reduced to some extent, the concentrated hydrochloric acid is added into the dilute brine from electrolysis, and the mixture is evenly mixed and then is added into a chlorate decomposer, and the decomposition of chlorate in the dilute brine is completed through preheating, heating, decomposition and cooling separation, and the gas phase parts are converged and then are added into ClO 2 And (3) treating the decomposed acidic dilute brine by a reduction tower, and acidifying the dilute brine from the discharge tank under the control of an automatic regulating valve to neutralize NaOH reversely transferred by the cathode chamber of the electrobath through the ionic membrane.
Example two
Referring to FIG. 4, the present invention provides the active chlorine (ClO) in the dilute brine - 、Cl 2 ) Is a disproportionation device of (a);
the implementation process is as follows: adding acidic fresh brine from an anode chamber of an electrolytic tank (at the temperature of 87 ℃), regulating the pH value to 4+/-0.5 by adding acidic fresh brine after chlorate decomposition, releasing most of chlorine, removing residual active chlorine in the fresh brine by the fresh brine and acidic multicomponent chlorine water after chlorine release, adding 32% NaOH (at the temperature of 88 ℃) from a cathode chamber of the electrolytic tank into the fresh brine under the control of a regulating valve, uniformly mixing by a static mixer, then adding into a temperature stabilizing heater, keeping the temperature of the fresh brine at 85-90 ℃, detecting the pH value of 5-6 by a pH value measuring instrument, transmitting the detected value to a caustic soda adding control valve, timely regulating the adding amount of the caustic soda, entering from an inlet at the top of a disproportionation reactor, and keeping the disproportionation reaction time (h) to be more than or equal to 180min to ensure that most of active chlorine (Cl) 2 、ClO - ) Disambiguation to ClO 3 - The residual chlorine is dissolved in the light brine togetherDischarging from the lower part, adding 5-15% Na 2 SO 3 The light brine reduced to the residual chlorine of zero and between 85 and 90 ℃ exchanges heat with refined brine of 45 to 55 ℃ from primary brine in a brine heat exchanger, the temperature of the primary refined brine is raised to more than 65 ℃ to be refined for the second time, and then electrolysis is carried out, and the light brine of-55 ℃ is subjected to denitration or salinization. And (3) discharging the electrolyzed dilute brine into a chlorate decomposition device from a branch pipe on the main pipe, decomposing chlorate in the dilute brine, recycling chlorine to the main pipe, and acidifying the decomposed acidic dilute brine to enter and exit the electrobath brine and condensing chlorine water from wet chlorine gas of chlorine hydrogen treatment.
Example III
Referring to fig. 5, the present invention provides a dilute brine disproportionation concentration device;
the implementation process is as follows: adding acidic fresh brine from an anode chamber of an electrolytic tank (at the temperature of 87 ℃), regulating the pH value to 4+/-0.5 by adding acidic fresh brine after chlorate decomposition, releasing most of chlorine, removing active chlorine remained in the fresh brine by adding 32% NaOH from a cathode chamber of the electrolytic tank (at the temperature of 88 ℃) into the fresh brine under the control of a regulating valve, uniformly mixing the fresh brine by a static mixer, then adding the fresh brine into a temperature stabilizing heater, keeping the temperature of the fresh brine at 84-90 ℃, detecting the pH value by a pH value measuring instrument to 5-6, transmitting the detected value to a caustic soda adding control valve, timely regulating the adding amount of the caustic soda, then entering from an inlet at the top of a disproportionation reactor, and keeping the disproportionation reaction time (h) to be more than or equal to 180min to ensure that most of active chlorine (Cl) 2 、ClO - ) Disambiguation to ClO 3 - The residual chlorine is dissolved in the light brine and discharged from the lower part of the brine, and 5 to 15 percent of Na is added 2 SO 3 The addition was reduced to zero residual chlorine. The dilute brine after disproportionation and reduction enters a dilute brine concentrating device, the dilute brine is concentrated to NaCl of 230-180 g/L, and the SO in the dilute brine is removed by denitration 4 2- The light brine after denitration and the primary brine are mixed according to the proportion and then are subjected to secondary refining and electrolysis. The discharged electrolysis fresh brine enters a chlorate decomposition device from a branch pipe on a main pipe, chlorate in the fresh brine is decomposed, chlorine is recovered to remove chlorine from the main pipe, and the decomposed acidic fresh brine is deacidified into the brine of an electrobath, the fresh brine of a discharge bath and wet chlorine from chlorine-hydrogen treatment are condensedChlorine water is discharged.
Compared with the existing dechlorination technology, the method and the device for treating chlorine and oxychloride in chlor-alkali discharged electrolysis dilute brine have the beneficial effects that:
1. creatively electrolyzes refined brine, discharges light brine and gas phase wet chlorine gas condensed chlorine water, acidizes and releases most of chlorine gas, and then disproportionates residual active chlorine into ClO under alkaline working condition 3 - Eliminating the oxidability of the sodium chloride and ClO in the dilute brine 3 - 、Cl 2 、ClO - All in ClO 3 - Form into chlorate decomposing device to decompose ClO 3 - Total decomposition (containing gas phase Cl) 2 ) Recovery of the recycled NaCl, cl 2 、H 2 O, the method is the simplest treatment process of the dilute brine and the chlorine water, omits physical dechlorination and vacuum system dechlorination of the chlorine water in the existing dechlorination device, and reduces the denitration load of the brine;
2. the method for eliminating active chlorine in the dilute brine has the advantages that the water quality of the dilute brine treated by the method is high, the oxidation-reduction potential is stable, the qualification rate of residual chlorine in the treated dilute brine is 100 percent, and compared with the method which has complicated physical vacuum dechlorination operation and is affected by superposition of various factors, the method has incomparable advantages of quality fluctuation of the dilute brine;
3. the heat energy of the dilute brine of the outlet tank is not lost, in a chloralkali device without dehydration requirement, the dilute brine of-87 ℃ is preheated to the temperature of 60-65 ℃ from 45-55 ℃ for primary brine, the secondary refined brine of the chelating resin tower is removed, and the dilute brine is cooled to the temperature of-50 ℃ for removing salt without reheating;
4. for enterprises with advantages of using underground rock salt, the light brine at the temperature of 87 ℃ can evaporate redundant water by utilizing the heat energy of the light brine for multiple times, and the alkali can be prepared by halogenated salt only by supplementing insufficient steam, so that the salt cost for caustic soda is greatly reduced by pipeline brine conveying;
5. the invention complies with the national energy conservation and emission reduction policy supported by priority, and on the large industrial chain of chlor-alkali, the phenomena of salt production by evaporation of the existing well brine and high energy consumption of water-soluble salt for chlor-alkali enterprises can be avoided, the theoretical basis of dechlorination of the existing dilute brine of the chlor-alkali industry is subverted, the dilute brine treatment process used for decades is modified, more valuable energy sources are saved for society, and the low-carbon, environment-friendly and sustainable development is realized in the aspect of chlor-alkali dilute brine treatment.
Claims (9)
1. The invention provides a method for treating chlorine and oxychloride in dilute brine by chlor-alkali electrolysis, which comprises the following steps: adding acidic multicomponent chlorine water into dilute brine (87 ℃) which releases chlorine after acidification from an electrolytic tank, adding 32% NaOH (88 ℃) to mix uniformly, controlling the temperature of the dilute brine to 87+/-3 ℃ by external heat, monitoring the pH value to 6+/-1 on line, and disproportionating active chlorine (Cl) in the dilute brine by a disproportionation device 2 、ClO - ) Is chlorate (ClO) 3 - ) The reaction time (h) is controlled to be 2-4 h, and the residual chlorine without disproportionation is formed by 5-10% Na 2 SO 3 Reducing, detecting that oxidation-reduction potential (ORP) of the dilute brine is qualified between-500 and 500mv, cooling the dilute brine to 45-55 ℃ for denitration or direct salt conversion, and concentrating the qualified dilute brine by a dilute brine concentrating device to obtain concentrated brine instead of primary brine; diverting a part of the acidified fresh brine from the electrolytic tank to decompose chlorate in the fresh brine, diverting the fresh brine according to the chlorate content in the fresh brine after the acidic chlorine release of the electrolytic tank, and heating high-purity hydrochloric acid (31% HCl) to 25-55 ℃ to reduce ClO in the mixed gas decomposed by the chlorate 2 Cl formation 2 The dilute brine and the hydrochloric acid are mixed evenly according to the technological requirement, then the mixture is put into a chlorate decomposer, preheated, heated, decomposed, cooled, separated into gas and liquid, the gas phase parts are converged and then reduced into pure chlorine gas by a high-purity hydrochloric acid in a reduction tower, and the decomposed acidic brine is electrolyzed to neutralize NaOH which is reversely permeated by a membrane.
2. The method for treating chlorine and oxychloride in dilute brine of chlor-alkali electrolysis according to claim 1, wherein the acidic multicomponent chlorine water is a chlorine water solution formed by dissolving chlorine in condensed water cooled by wet chlorine generated by an anode chamber of an electrolytic tank, the pH value of the decomposed acidic brine is adjusted to 2+/-0.5 before the decomposed acidic brine enters a chlorine water storage tank, most of the chlorine is only 500-200 mg/L after the chlorine water escapes from the chlorine water tank, the acidified chlorine water is sent into the dilute brine of electrolysis, and the escaped chlorine is recycled to a chlorine header pipe.
3. The method for treating chlorine and oxychloride in chlor-alkali discharge electrolysis brine according to claim 1 and 2, wherein the decomposed acidic brine is acidic brine obtained by decomposing chlorate in the discharge electrolysis tank brine, and the component NaCl of the acidic brine is 100-200 g/L, HCl, 15-50 g/L, naClO 3 0～3g/L、T≥80℃。
4. The method for treating chlorine and oxychloride in dilute brine by chlor-alkali electrolysis according to claim 1, wherein the method is characterized in that when chlorate in the dilute brine is decomposed, the ClO is firstly added after the high-purity hydrochloric acid (31% HCl) is heated 2 Reduction tower reduces ClO in gas phase of chlorate decomposer 2 And adding light brine according to the known process proportion requirement to decompose chlorate.
5. The method for treating chlorine and oxychloride in dilute brine by chlor-alkali electrolysis according to claim 1, wherein the residual chlorine (Cl 2 、ClO - ) From 5 to 10 percent of Na 2 SO 3 The sodium sulfite solution is generally added immediately after the disproportionation reaction, and the point of addition is after the waste heat utilization when the waste heat utilization device does not require the residual chlorine in the dilute brine.
6. The method for treating chlorine and oxychloride in dilute brine of chlor-alkali electrolysis according to claim 1, wherein the concentrated strong brine NaCl is 225-270 g/L, naClO 3 And the concentration of active chlorine is less than or equal to 5g/L, and the alkali preparation by halogenated salt is realized after the excess water in the light salt water is disproportionated and evaporated.
7. A device for treating and producing chlorine and oxychloride in dilute brine by chlor-alkali electrolysis, which is characterized in that the device comprises the full decomposition of chlorate in dilute brine and the active chlorine (Cl) of the dilute brine by the method for treating chlorine and oxychloride in dilute brine by the method according to claim 1 2 、ClO - ) Connecting pipelines, valves, automatic regulating valves and various signal display instruments between the disproportionation two parts and equipment;
first, the brine chlorate full decomposition device comprises a chlorate decomposer and ClO 2 A reduction tower combination;
the chlorate decomposer is used for decomposing chlorate in the dilute brine, and comprises 5 functional areas, namely a preheating area, a heating area, a decomposing area, a cooling area and a gas-liquid separation storage area, wherein the inlet is connected with the acidified dilute brine, the heating area is provided with a steam inlet and a condensed water outlet, the decomposing area is provided with a gas outlet, a temperature measuring and pressure measuring port, and a gas outlet pipe is connected with the ClO through another gas outlet pipe 2 The gas outlet pipe is combined with the top outlet, and the liquid outlet pipe is connected with a salt water pipe of an electric tank and an inlet pipe of a chlorine water tank;
ClO 2 the reduction tower is combined with ClO 2 Reduction tower and hydrochloric acid heater of auxiliary equipment for ClO in gas phase after chlorate decomposition 2 Reduction purification to Cl 2 ，ClO 2 The gas phase inlet pipe of the reduction tower is connected with the gas phase outlet pipe of the chlorate decomposer, the gas phase outlet pipe of the reduction tower is connected with the electrolytic chlorine main pipe, the liquid inlet of the reduction tower is connected with the hydrochloric acid pipe, and the liquid phase outlet of the reduction tower is connected with the dilute salt water pipe from electrolysis and then is connected with the chlorate decomposer, clO 2 The front of the reduction tower is connected with an outlet pipe of a hydrochloric acid heater, a temperature measuring instrument is arranged on the reduction tower, an inlet pipe of the heater is connected with a high-purity hydrochloric acid (31% HCl) supply pipe, and a steam inlet and a condensate water outlet are arranged on the heater;
secondly, the electrolytic light brine active chlorine (Cl) 2 、ClO - ) The disproportionation device comprises a static mixer, a temperature stabilizing heater, a disproportionation reactor, a brine heat exchanger and light brine active chlorine (Cl) 2 、ClO - ) Disproportionation in a disproportionation reactor to form ClO 3 - A liquid level measuring instrument is arranged on the disproportionation reactor; the front of the brine main pipe is connected with an electrolytic brine circulating output pump, and then is connected with a static mixer, the upper part of the brine main pipe is respectively connected with an acidified chlorine water adding pipe and a 32% NaOH adding pipe, and the outlet pipe of the static mixer is connected withThe temperature stabilizing heater is provided with a steam adding pipe and a condensed water discharging pipe, the outlet of the temperature stabilizing heater is connected with the inlet pipe of the disproportionation reactor, the temperature measuring instrument is arranged on the outlet pipe of the disproportionation reactor, the outlet pipe of the disproportionation reactor is connected with the inlet of the brine heater, and 5 to 10 percent of Na is arranged on the outlet pipe of the disproportionation reactor 2 SO 3 The inlet pipe is connected with a primary brine system, the outlet pipe is connected with a redox electrode potential measuring instrument, the primary brine inlet pipe at the heating side of the heat exchanger is connected with a primary brine pipe, the outlet is connected with a secondary refined brine pipeline in the area, and the outlet pipe of the disproportionation reactor can be connected with a dilute brine concentration unit.
8. The device for treating chlorine and oxychloride in dilute brine by chlor-alkali electrolysis according to claim 6, wherein the outlet pipe of the disproportionation reactor is also connected with a dilute brine concentration unit, the outlet pipe of the dilute brine concentration unit enters the inlet of the denitration unit, the outlet pipe of the denitration unit is connected with a primary brine main pipe, and then is connected with the brine inlet pipe of the secondary refining unit.
9. The apparatus for treating chlorine and oxychloride in dilute brine by chlor-alkali electrolysis according to claim 6, wherein 5% -10% of Na 2 SO 3 The concentration device with the adding position of the adding pipe requiring zero residual chlorine for the quality of the fresh brine is connected to the outlet pipe of the disproportionation device, and other waste heat utilization devices are connected to the fresh brine pipeline after the waste heat utilization is finished.
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