CN110818163A - Ion membrane electrolytic dechlorination fresh brine recycling system and method - Google Patents
Ion membrane electrolytic dechlorination fresh brine recycling system and method Download PDFInfo
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- CN110818163A CN110818163A CN201911161040.3A CN201911161040A CN110818163A CN 110818163 A CN110818163 A CN 110818163A CN 201911161040 A CN201911161040 A CN 201911161040A CN 110818163 A CN110818163 A CN 110818163A
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- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 title abstract description 144
- 239000012267 brine Substances 0.000 title abstract description 142
- 238000006298 dechlorination reaction Methods 0.000 title abstract description 40
- 239000012528 membrane Substances 0.000 title abstract description 32
- 238000004064 recycling Methods 0.000 title abstract description 19
- 238000000034 method Methods 0.000 title abstract description 9
- 150000003839 salts Chemical class 0.000 abstract description 97
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 56
- 239000002351 wastewater Substances 0.000 abstract description 53
- 238000001704 evaporation Methods 0.000 abstract description 38
- 230000008020 evaporation Effects 0.000 abstract description 38
- 238000005868 electrolysis reaction Methods 0.000 abstract description 32
- 238000002425 crystallisation Methods 0.000 abstract description 29
- 230000008025 crystallization Effects 0.000 abstract description 29
- 238000009292 forward osmosis Methods 0.000 abstract description 29
- 238000000909 electrodialysis Methods 0.000 abstract description 20
- 230000008014 freezing Effects 0.000 abstract description 14
- 238000007710 freezing Methods 0.000 abstract description 14
- 238000001914 filtration Methods 0.000 abstract description 10
- 239000013505 freshwater Substances 0.000 abstract description 8
- 239000002918 waste heat Substances 0.000 abstract description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 21
- 239000007788 liquid Substances 0.000 description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000011780 sodium chloride Substances 0.000 description 12
- 150000002500 ions Chemical class 0.000 description 11
- 239000011550 stock solution Substances 0.000 description 11
- 239000000243 solution Substances 0.000 description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000009270 solid waste treatment Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 230000003204 osmotic effect Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 235000011121 sodium hydroxide Nutrition 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 3
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 125000001309 chloro group Chemical group Cl* 0.000 description 3
- 239000012141 concentrate Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 229910001425 magnesium ion Inorganic materials 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 230000000593 degrading effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 244000005700 microbiome Species 0.000 description 2
- 239000002574 poison Substances 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000001728 nano-filtration Methods 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
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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
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/16—Evaporating by spraying
- B01D1/18—Evaporating by spraying to obtain dry solids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/30—Accessories for evaporators ; Constructional details thereof
-
- 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
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- 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
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/445—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by forward osmosis
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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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
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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
- C02F2101/30—Organic 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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Abstract
The invention discloses an ion membrane electrolysis dechlorination light brine recycling system which comprises an electrolysis system, wherein the electrolysis system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a light brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with the freezing denitration system, the forward osmosis concentration system, the electrodialysis concentration system, the fresh water biochemical system, the filtering system, the salt dissolving system and the strong brine treatment system, and the strong brine treatment system is communicated with the electrolysis system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines. The invention also discloses a utilization method of the ionic membrane electrolytic dechlorination light brine recycling system, low-temperature evaporation concentration and low-temperature evaporation crystallization are realized by utilizing the waste heat of the light brine, the salt dissolving load and the cost of refined brine are reduced, most of water in the high-salt organic wastewater is recycled, and organic balance of electrolysis, salt dissolving and system water replenishing is realized.
Description
Technical Field
The invention belongs to the technical field of brine treatment, and particularly relates to an ionic membrane electrolytic dechlorination fresh brine recycling system and a utilization method of the ionic membrane electrolytic dechlorination fresh brine recycling system.
Background
In the chlor-alkali industry of China, the concentration of sodium chloride of the light brine discharged from an ion membrane electrolytic cell is 220g/L and the temperature is 80-90 ℃, the temperature of the light brine is 70-80 ℃ after dechlorination, the main treatment mode of the dechlorination light brine at present is that part of the light brine exchanges heat with the strong brine after salt dissolving, then the light brine enters a freezing and denitration system after being cooled by circulating water, and the light brine after denitration or non-denitration is mixed with the water supplement of a production system and then enters the salt dissolving system. The freezing denitration system is utilized to reduce the sulfate radical content, and the waste heat of partial light brine is also utilized, but the better water quality, higher salt concentration and water temperature of dechlorination light brine cannot be effectively utilized.
Disclosure of Invention
The invention aims to provide a system for recycling dechlorination light brine through ion membrane electrolysis, which solves the problems that the conventional dechlorination light brine recycling system is high in energy consumption and cannot effectively utilize the higher water temperature and salt concentration of the light brine, and improves the utilization rate of the dechlorination light brine.
The invention also aims to provide a utilization method of the ion membrane electrolytic dechlorination fresh brine recycling system.
The first technical scheme adopted by the invention is that the ion membrane electrolytic dechlorination fresh brine recycling system comprises an electrolytic system, wherein the electrolytic system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a fresh brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with the freezing denitration system, the forward osmosis concentration system, the electrodialysis concentration system, the fresh water biochemical system, the filtering system, the salt dissolving system and the strong brine treatment system, and the strong brine treatment system is communicated with the electrolysis system; the electrodialysis concentration system is also sequentially connected with the low-temperature evaporation crystallization system and the solid waste treatment system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines.
The present invention is also characterized in that,
the forward osmosis concentration system includes a forward osmosis membrane that divides the system into a feed side and a draw side.
According to the second technical scheme, the utilization method of the ionic membrane electrolytic dechlorination light salt brine recycling system comprises the steps of concentrating high-salt-content organic wastewater through a forward osmosis concentration system by utilizing osmotic pressure difference between dechlorination light salt brine and the high-salt-content organic wastewater, separating salt and organic matters in the high-salt-content organic wastewater through an electrodialysis concentration system, enabling the separated high-salt-content wastewater to enter a low-temperature evaporation crystallization system, performing low-temperature evaporation crystallization treatment on the high-salt-content wastewater by utilizing heat of the dechlorination light salt brine through the low-temperature evaporation crystallization system, degrading organic matters in the organic wastewater through a fresh water biochemical system, and filtering the organic wastewater and recycling the organic matters to a salt dissolving system;
the low-temperature evaporation concentration system concentrates part of the fresh brine after dechlorination to reach the concentration of saturated brine, and then the concentrated fresh brine directly enters the electrolysis system and the fresh brine enters the salt dissolving system;
the two-stage heat exchange system enables part of dechlorinated light brine and salt-dissolved strong brine to exchange heat and then enter a freezing denitration system, the denitrated light brine is used as a drawing liquid of a forward osmosis concentration system, the drawn light brine enters a salt dissolving system, a stock solution is concentrated and then enters an electrodialysis concentration system, the electrodialysis concentration system separates the brine and organic wastewater in the wastewater, the brine enters a low-temperature evaporation crystallization system, the low-temperature evaporation crystallization system utilizes the heat of the dechlorinated light brine to enable the salt in the brine to reach a crystallization state, and the crystallized salt enters a solid waste treatment system; the organic wastewater enters a fresh water biochemical system to degrade organic matters in the organic wastewater, the organic wastewater is recycled to a salt dissolving system after passing through a filtering system, a strong brine treatment system is used for removing inorganic ammonia, calcium ions, magnesium ions and other impurities in the strong brine after salt dissolving, and the strong brine after being treated by the strong brine treatment system is continuously circulated to an electrolysis system;
the dilute brine storage system is used for enabling the two-stage heat exchange system and the low-temperature evaporation concentration system to use the residual dilute brine for caching and then salt melting.
The present invention is also characterized in that,
the forward osmosis concentration system comprises a forward osmosis membrane, and the forward osmosis membrane divides the system into a stock solution side and a drawing solution side; the liquid side of the drawing liquid is dechlorinated light salt brine, the stock solution side is high-salinity organic wastewater, and water in the stock solution is drawn to the liquid side of the drawing liquid through the forward osmosis membrane by using osmotic pressure difference.
The low-temperature evaporative crystallization system heats dry air by utilizing the heat of the light salt brine, the light salt brine passes through the drying air, the light salt brine is concentrated and crystallized, and condensed water after heat exchange and cooling of damp-heat air enters the salt dissolving system.
The two-stage heat exchange system comprises a strong brine side and a circulating water side, the light brine processed by the dechlorination system is subjected to heat exchange on the strong brine side and then on the circulating water side, and the temperature of the light brine is reduced from 70-80 ℃ to below 40 ℃ after heat exchange.
The electrolysis system can electrolyze sodium chloride solution with the concentration of 300-310g/L, the anode of the product is chlorine and weak brine, and the cathode is hydrogen and 20-33% sodium hydroxide solution.
The ion membrane electrolysis dechlorination light salt brine recycling system comprises an electrolysis system, wherein the electrolysis system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a light salt brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with the freezing denitration system, the forward osmosis concentration system, the electrodialysis concentration system, the fresh water biochemical system, the filtering system, the salt dissolving system and the strong brine treatment system, and the strong brine treatment system is communicated with the electrolysis system; the electrodialysis concentration system is also sequentially connected with the low-temperature evaporation crystallization system and the solid waste treatment system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines.
The invention has the beneficial effects that: the invention utilizes the better water quality condition and higher water temperature of the dechlorinated light brine, achieves the concentration required by the electrolysis system through evaporation concentration and then recycles the dechlorinated light brine, and utilizes the higher salt concentration and higher water temperature thereof to treat the high-salt organic wastewater, thereby improving the utilization rate of the dechlorinated light brine.
1. The system utilizes the waste heat of the ionic membrane electrolytic dechlorination fresh brine to realize the operation of a low-temperature evaporation concentration and low-temperature evaporation crystallization system;
2. the system directly recycles the electrolysis system through low-temperature evaporation concentration, thereby reducing the salt dissolving load and the cost of refined brine;
3. the system utilizes the high-salt characteristic of dechlorinated light salt brine, combines a forward osmosis concentration system, an electrodialysis system and a low-temperature evaporation crystallization system to treat the salt-containing organic wastewater, and recovers most of water in the salt-containing organic wastewater;
4. the system realizes organic balance of electrolysis, salt dissolving and system water replenishing.
Drawings
FIG. 1 is a schematic diagram of the structure of an ionic membrane electrolytic dechlorination dilute brine recycling system according to the present invention;
FIG. 2 is a prior art dechlorinated light brine treatment system.
Detailed Description
The specific structure of the ionic membrane electrolysis dechlorination light brine recycling system provided by the invention is shown in figure 1, and the system comprises an electrolysis system, wherein the electrolysis system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a light brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with a freezing denitration system, a forward osmosis concentration system, an electrodialysis concentration system, a fresh water biochemical system, a filtering system, a salt dissolving system and a strong brine treatment system, and the strong brine treatment system is communicated with an electrolysis system; the electrodialysis concentration system is also sequentially connected with a low-temperature evaporation crystallization system and a solid waste treatment system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines.
An electrolysis system: electrolyzing sodium chloride solution with the concentration of 300-310g/L, wherein the anode of the product is chlorine and light saline water, and the cathode is hydrogen and 20-32% sodium hydroxide solution.
A dechlorination system: the free chlorine in the fresh brine is removed through the combination of vacuum dechlorination and chemical dechlorination.
Two-stage heat exchange system: the dechlorinated light salt water exchanges heat with strong brine firstly and then with circulating water, and the temperature is reduced from 70-80 ℃ to below 40 ℃ after heat exchange.
Freezing denitration: sulfate radicals in the fresh brine are separated by a nanofiltration membrane, and sodium sulfate crystals are removed by cooling the frozen brine.
Forward osmosis concentration system: the raw liquid side is high-salt organic wastewater, the drawing liquid side is dechlorinated light salt brine, water in the raw liquid is drawn through a forward osmosis membrane, and the raw liquid is concentrated.
An electrodialysis concentration system: the system separates the saline water and the organic wastewater in the wastewater, the saline water enters the low-temperature evaporation crystallization system, and the organic wastewater enters the biochemical system.
A biochemical system: the organic waste water is mixed and contacted with the microorganisms, organic matters and certain inorganic poisons (such as cyanides, sulfides and the like) in the waste water are decomposed by utilizing the biochemical action in the microorganisms, the unstable organic matters and inorganic poisons are converted into nontoxic substances, and the water from the biochemical system can be returned to the production system to replace the production water for use.
A filtering system: the suspended matter in the water was filtered through a sand filter.
Salt dissolving system: a dilute brine (sodium chloride solution) having a concentration of 210g/L or less is brought into direct contact with the salt layer to form a concentrated brine having a concentration of 300g/L or more.
Strong brine processing system: the system removes the impurities such as inorganic ammonia, calcium ions, magnesium ions and the like in the concentrated brine, and the indexes of the electrolysis system require that the inorganic ammonia is less than or equal to 1ppm and the calcium and magnesium are less than or equal to 20 ppb.
Low-temperature evaporation concentration system: the heat of the dilute brine is utilized to heat the dry air and the dry air passes through the dilute brine, the dilute brine is concentrated, and the condensed water formed by the damp and hot air after heat exchange and temperature reduction enters the salt dissolving system.
A utilization method of an ionic membrane electrolytic dechlorination light salt brine recycling system comprises the steps of utilizing osmotic pressure difference between dechlorination light salt brine and high-salt organic wastewater, concentrating the high-salt organic wastewater through a forward osmosis concentration system, separating salt and organic matters in the high-salt organic wastewater through the electrodialysis concentration system, enabling the separated high-salt organic wastewater to enter a low-temperature evaporative crystallization system, carrying out low-temperature evaporative crystallization treatment on the high-salt wastewater through heat of the dechlorination light salt brine through the low-temperature evaporative crystallization, degrading the organic matters in the organic wastewater through a light salt biochemical system, and filtering and recycling the organic wastewater to a salt dissolving system;
the low-temperature evaporation concentration system concentrates part of the fresh brine after dechlorination to reach the concentration of saturated brine, and then the concentrated fresh brine directly enters the electrolysis system and the fresh brine enters the salt dissolving system;
the two-stage heat exchange system enables part of dechlorinated light brine and salt-dissolved strong brine to exchange heat and then enter a freezing denitration system, the denitrated light brine is used as a drawing liquid of a forward osmosis concentration system, the drawn light brine enters a salt dissolving system, a stock solution is concentrated and then enters an electrodialysis concentration system, the electrodialysis concentration system separates the brine and organic wastewater in the wastewater, the brine enters a low-temperature evaporation crystallization system, the low-temperature evaporation crystallization system utilizes the heat of the dechlorinated light brine to enable the salt in the brine to reach a crystallization state, and the crystallized salt enters a solid waste treatment system; the organic wastewater enters a fresh water biochemical system to degrade organic matters in the organic wastewater, the organic wastewater is recycled to a salt dissolving system after passing through a filtering system, a strong brine treatment system is used for removing inorganic ammonia, calcium ions, magnesium ions and other impurities in the strong brine after salt dissolving, and the strong brine after being treated by the strong brine treatment system is continuously circulated to an electrolysis system;
the dilute brine storage system is used for enabling the two-stage heat exchange system and the low-temperature evaporation concentration system to use the residual dilute brine for caching and then salt melting.
The forward osmosis concentration system comprises a forward osmosis membrane, and the forward osmosis membrane divides the system into a stock solution side and a drawing solution side; the liquid side of the drawing liquid is dechlorinated light salt brine, the stock solution side is high-salinity organic wastewater, and water in the stock solution is drawn to the liquid side of the drawing liquid through the forward osmosis membrane by using osmotic pressure difference.
The low-temperature evaporative crystallization system heats dry air by utilizing the heat of the light salt brine, the light salt brine passes through the drying air, the light salt brine is concentrated and crystallized, and condensed water after heat exchange and cooling of damp-heat air enters the salt dissolving system.
The two-stage heat exchange system comprises a strong brine side and a circulating water side, the light brine processed by the dechlorination system is subjected to heat exchange on the strong brine side and then on the circulating water side, and the temperature of the light brine is reduced from 70-80 ℃ to below 40 ℃ after heat exchange.
The electrolysis system can electrolyze sodium chloride solution with the concentration of 300-310g/L, the anode of the product is chlorine and weak brine, and the cathode is hydrogen and 20-33% sodium hydroxide solution.
The present invention is further illustrated by the following specific examples.
Example 1
In a production enterprise adopting products such as calcium carbide-process polyvinyl chloride, ionic membrane caustic soda and the like, the dilute brine discharged from an ionic membrane electrolytic cell enters a freezing and denitration system after two-stage heat exchange, and the temperature of the dilute brine is reduced from 80 ℃ to 39 ℃ after the heat exchange; the denitrated light salt water enters a liquid drawing side of a forward osmosis concentration system, a stock solution side is high-salt organic wastewater which is obtained by treating wastewater for synthesizing vinyl chloride by an alkaline washing tower and adjusting the pH value by hydrochloric acid, the TDS of the high-salt organic wastewater is over 160g/L after forward osmosis concentration, then the high-salt organic wastewater enters the electrodialysis concentration system, the TDS of the salt water side is over 200g/L after concentration and separation, the salt content of the organic wastewater side is below 1.5 percent, and the requirement of biochemical indexes is met. The high salt-containing wastewater enters a low-temperature evaporative crystallization system for further concentration until crystallization, and the water content of the crystallized salt is 40 percent. The content of sodium chloride in the dechlorinated weak brine subjected to ion membrane electrolysis is 290g/L after low-temperature evaporation and concentration, and the dechlorinated weak brine is mixed with water treated by strong brine and then enters an electrolysis system.
Example 2
In the same enterprise as the enterprise in the embodiment 1, the dilute brine discharged from the ion membrane electrolytic cell enters a freezing and denitration system after two-stage heat exchange, and the temperature of the dilute brine is reduced from 75 ℃ to 36 ℃ after the heat exchange; the denitrated light salt water enters a liquid drawing side of a forward osmosis concentration system, a stock solution side is high-salt organic wastewater which is obtained by treating wastewater for synthesizing vinyl chloride by an alkaline washing tower and adjusting the pH value by hydrochloric acid, the TDS of the high-salt organic wastewater is over 160g/L after forward osmosis concentration, then the high-salt organic wastewater enters the electrodialysis concentration system, the TDS of the salt water side is over 200g/L after concentration and separation, the salt content of the organic wastewater side is below 1.5 percent, and the requirement of biochemical indexes is met. The high salt-containing wastewater enters a low-temperature evaporative crystallization system for further concentration until crystallization, and the water content of the crystallized salt is 50%. The content of sodium chloride in the dechlorinated weak brine subjected to ion membrane electrolysis is 310g/L after low-temperature evaporation and concentration, and the dechlorinated weak brine is mixed with water treated by strong brine and then enters an electrolysis system.
Example 3
In the same enterprise as the enterprise in the embodiment 1, the dilute brine discharged from the ion membrane electrolytic cell enters a freezing and denitration system after two-stage heat exchange, and the temperature of the dilute brine is reduced to 35 ℃ from 70 ℃ after the heat exchange; the denitrated light salt water enters a liquid drawing side of a forward osmosis concentration system, a stock solution side is high-salt organic wastewater which is obtained by treating wastewater for synthesizing vinyl chloride by an alkaline washing tower and adjusting the pH value by hydrochloric acid, the TDS of the high-salt organic wastewater is over 160g/L after forward osmosis concentration, then the high-salt organic wastewater enters the electrodialysis concentration system, the TDS of the salt water side is over 200g/L after concentration and separation, the salt content of the organic wastewater side is below 1.5 percent, and the requirement of biochemical indexes is met. The high salt-containing wastewater enters a low-temperature evaporative crystallization system for further concentration until crystallization, and the water content of the crystallized salt is 45%. The content of sodium chloride in the dechlorinated weak brine subjected to ion membrane electrolysis is 300g/L after low-temperature evaporation and concentration, and the dechlorinated weak brine is mixed with water treated by strong brine and then enters an electrolysis system.
As shown in fig. 2, the main treatment method of the dechlorinated light salt brine at present is to exchange heat between part of the light salt brine and the strong brine after salt dissolving, then exchange heat with circulating water to reduce the temperature, and then enter a freezing denitration system, and the denitrated or non-denitrated light salt brine is mixed with the water supplement of a production system and then enters a salt dissolving system. The freezing denitration system is utilized to reduce the sulfate radical content in the light brine, and the waste heat of partial light brine is utilized through heat exchange with the strong brine, but the better water quality, higher salt concentration and water temperature of dechlorination light brine cannot be effectively utilized.
The low-temperature evaporation concentration system utilizes the heat of the dechlorinated light salt brine at 70-80 ℃ to concentrate the dechlorinated light salt brine to reach the sodium chloride content of 290-320 g/L through a low-temperature evaporation concentration technology, so that the dechlorinated light salt brine reaches the index of directly recycling the electrolytic cell, and the evaporative cooling water enters the salt dissolving system.
In the light salt water recycling system, dechlorinated light salt water is adopted as forward osmosis concentration drawing liquid, the drawn light salt water enters a salt dissolving system, raw liquid enters an electrodialysis concentration system after forward osmosis concentration, electrodialysis concentrated water enters a low-temperature evaporation crystallization system, the low-temperature evaporation crystallization adopts heat of the dechlorinated light salt water at 70-80 ℃, and the electrodialyzed fresh water is recycled to the salt dissolving system after organic matters are degraded by a biochemical filtration system.
Claims (8)
1. The ion membrane electrolysis dechlorination fresh brine recycling system is characterized by comprising an electrolysis system, wherein the electrolysis system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a fresh brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with a freezing denitration system, a forward osmosis concentration system, an electrodialysis concentration system, a fresh water biochemical system, a filtering system, a salt dissolving system and a strong brine treatment system, and the strong brine treatment system is communicated with an electrolysis system; the electrodialysis concentration system is also sequentially connected with a low-temperature evaporation crystallization system and a solid waste treatment system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines.
2. The system of claim 1, wherein the forward osmosis concentration system comprises a forward osmosis membrane, and the forward osmosis membrane divides the system into a feed side and a draw side.
3. A utilization method of an ionic membrane electrolytic dechlorination light salt brine recycling system is characterized in that the organic wastewater with high salt content is concentrated through a forward osmosis concentration system by utilizing the osmotic pressure difference between the dechlorination light salt brine and the organic wastewater with high salt content, the salt and the organic matters in the organic wastewater with high salt content are separated by utilizing the electrodialysis concentration system, the separated high salt content wastewater enters a low-temperature evaporative crystallization system, the low-temperature evaporative crystallization utilizes the heat of the dechlorination light salt brine to carry out low-temperature evaporative crystallization treatment on the high salt content wastewater, the organic matters in the organic wastewater are degraded through a fresh water biochemical system, and the organic wastewater is filtered and then recycled to a salt dissolving system;
the low-temperature evaporation concentration system concentrates part of the fresh brine after dechlorination to reach the concentration of saturated brine, and then the concentrated fresh brine directly enters the electrolysis system and the fresh brine enters the salt dissolving system;
the two-stage heat exchange system enables part of dechlorinated light brine and salt-dissolved strong brine to exchange heat and then enter a freezing denitration system, the denitrated light brine is used as a drawing liquid of a forward osmosis concentration system, the drawn light brine enters a salt dissolving system, a stock solution is concentrated and then enters an electrodialysis concentration system, the electrodialysis concentration system separates the brine and organic wastewater in the wastewater, the brine enters a low-temperature evaporation crystallization system, the low-temperature evaporation crystallization system utilizes the heat of the dechlorinated light brine to enable the salt in the brine to reach a crystallization state, and the crystallized salt enters a solid waste treatment system; the organic wastewater enters a fresh water biochemical system to degrade organic matters in the organic wastewater, the organic wastewater is recycled to a salt dissolving system after passing through a filtering system, a strong brine treatment system is used for removing inorganic ammonia, calcium ions, magnesium ions and other impurities in the strong brine after salt dissolving, and the strong brine after being treated by the strong brine treatment system is continuously circulated to an electrolysis system;
the dilute brine storage system is used for enabling the two-stage heat exchange system and the low-temperature evaporation concentration system to use the residual dilute brine for caching and then salt melting.
4. The utilization method of the ionic membrane electrolytic dechlorination freshwater recycling system according to claim 3, characterized in that the forward osmosis concentration system comprises a forward osmosis membrane, and the forward osmosis membrane divides the system into a raw liquid side and a draw liquid side; the liquid side of drawing is dechlorinated light salt brine, the stock solution side is high-salinity organic wastewater, and water in the stock solution is drawn to the liquid side of drawing through the forward osmosis membrane by using osmotic pressure difference.
5. The utilization method of the ionic membrane electrolytic dechlorination fresh salt water recycling system according to claim 3, characterized in that the low-temperature evaporative crystallization system heats dry air and passes through fresh salt water by utilizing the heat of the fresh salt water, the fresh salt water is concentrated and crystallized, and condensed water after being cooled by the heat exchange of damp-heat air enters the salt melting system.
6. The utilization method of the ionic membrane electrolytic dechlorination fresh brine recycling system according to claim 3, wherein the two-stage heat exchange system comprises a strong brine side and a circulating water side, the fresh brine processed by the dechlorination system is subjected to heat exchange on the strong brine side and then on the circulating water side, and the temperature of the fresh brine is reduced from 70-80 ℃ to below 40 ℃ after heat exchange.
7. The method as claimed in claim 3, wherein the electrolysis system is capable of electrolyzing 310g/L NaCl solution with concentration of 300-.
8. The utilization method of the ionic membrane electrolysis dechlorination fresh brine recycling system according to claim 3, wherein the ionic membrane electrolysis dechlorination fresh brine recycling system comprises an electrolysis system, the electrolysis system is communicated with a dechlorination system, and the dechlorination system is respectively connected with a two-stage heat exchange system, a fresh brine storage system and a low-temperature evaporation concentration system; the two-stage heat exchange system is sequentially connected with a freezing denitration system, a forward osmosis concentration system, an electrodialysis concentration system, a fresh water biochemical system, a filtering system, a salt dissolving system and a strong brine treatment system, and the strong brine treatment system is communicated with an electrolysis system; the electrodialysis concentration system is also sequentially connected with a low-temperature evaporation crystallization system and a solid waste treatment system; the low-temperature evaporation concentration system and the light salt water storage system are respectively communicated to the salt dissolving system through pipelines.
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