CN113800690A - Power plant desulfurization wastewater zero-discharge treatment process and system based on electrodialysis technology - Google Patents
Power plant desulfurization wastewater zero-discharge treatment process and system based on electrodialysis technology Download PDFInfo
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- CN113800690A CN113800690A CN202111127310.6A CN202111127310A CN113800690A CN 113800690 A CN113800690 A CN 113800690A CN 202111127310 A CN202111127310 A CN 202111127310A CN 113800690 A CN113800690 A CN 113800690A
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- 239000002351 wastewater Substances 0.000 title claims abstract description 88
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 76
- 230000023556 desulfurization Effects 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 64
- 230000008569 process Effects 0.000 title claims abstract description 55
- 238000000909 electrodialysis Methods 0.000 title claims abstract description 54
- 238000005516 engineering process Methods 0.000 title claims abstract description 29
- 208000028659 discharge Diseases 0.000 title claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 129
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 110
- 238000001728 nano-filtration Methods 0.000 claims abstract description 98
- 239000012528 membrane Substances 0.000 claims abstract description 89
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims abstract description 60
- 239000012452 mother liquor Substances 0.000 claims abstract description 54
- 239000011780 sodium chloride Substances 0.000 claims abstract description 52
- 239000013505 freshwater Substances 0.000 claims abstract description 47
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims abstract description 30
- 235000019341 magnesium sulphate Nutrition 0.000 claims abstract description 30
- 150000003839 salts Chemical class 0.000 claims abstract description 30
- 150000001768 cations Chemical class 0.000 claims abstract description 27
- 238000005352 clarification Methods 0.000 claims abstract description 26
- 238000002425 crystallisation Methods 0.000 claims abstract description 26
- 230000008025 crystallization Effects 0.000 claims abstract description 26
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 23
- 239000000243 solution Substances 0.000 claims abstract description 21
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 159000000003 magnesium salts Chemical class 0.000 claims abstract description 14
- 239000012267 brine Substances 0.000 claims abstract description 13
- 239000010802 sludge Substances 0.000 claims abstract description 13
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 13
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- 238000007710 freezing Methods 0.000 claims abstract description 10
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- 238000000926 separation method Methods 0.000 claims abstract description 10
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- 230000008020 evaporation Effects 0.000 claims description 31
- 238000011084 recovery Methods 0.000 claims description 17
- 229910001385 heavy metal Inorganic materials 0.000 claims description 14
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- 229940039790 sodium oxalate Drugs 0.000 claims description 5
- 238000000108 ultra-filtration Methods 0.000 claims description 5
- 150000003568 thioethers Chemical class 0.000 claims description 4
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- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000008394 flocculating agent Substances 0.000 claims description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 3
- 229910052753 mercury Inorganic materials 0.000 claims description 3
- 150000004692 metal hydroxides Chemical class 0.000 claims description 3
- 239000012266 salt solution Substances 0.000 claims description 3
- 239000006228 supernatant Substances 0.000 claims description 3
- 150000004679 hydroxides Chemical class 0.000 claims description 2
- 238000012545 processing Methods 0.000 claims description 2
- 238000004821 distillation Methods 0.000 description 7
- -1 fluorine ions Chemical class 0.000 description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 230000008901 benefit Effects 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 229910052731 fluorine Inorganic materials 0.000 description 6
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- 239000010703 silicon Substances 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 5
- 239000003344 environmental pollutant Substances 0.000 description 5
- 239000010440 gypsum Substances 0.000 description 5
- 229910052602 gypsum Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 231100000719 pollutant Toxicity 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 238000004065 wastewater treatment Methods 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 239000011552 falling film Substances 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 235000019738 Limestone Nutrition 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 238000005189 flocculation Methods 0.000 description 3
- 230000016615 flocculation Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000011033 desalting Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 229910001425 magnesium ion Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 229920002401 polyacrylamide Polymers 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 239000007832 Na2SO4 Substances 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
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical class OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
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- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000003311 flocculating effect Effects 0.000 description 1
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- 239000010842 industrial wastewater Substances 0.000 description 1
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000011734 sodium Substances 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/04—Chlorides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/40—Magnesium sulfates
-
- 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
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- 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
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- 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
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- 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
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
-
- 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
-
- 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
- C02F1/62—Heavy metal 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/122—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using filter presses
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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
- C02F2101/20—Heavy metals or heavy metal 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
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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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
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
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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
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
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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
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
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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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- Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
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- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
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Abstract
The invention relates to a power plant desulfurization wastewater zero-discharge treatment process and system based on an electrodialysis technology, and belongs to the field of water treatment. The treatment process comprises the following steps: raw water of the desulfurization wastewater enters a triple box for process treatment; the effluent of the triple box enters a clarification tank; the process treatment of the three headers and the sedimentation sludge generated in the clarification tank; the filtered water enters a nanofiltration membrane system to carry out primary salt separation of divalent ions; fresh water in the nanofiltration membrane fresh water tank enters a monovalent cation selective electrodialysis system; concentrating by an SWRO system to obtain high-concentration reverse osmosis concentrated water; the concentrated solution is mainly high-concentration sodium chloride brine; in a nanofiltration membrane concentrated water tank, nanofiltration concentrated water and reverse osmosis concentrated water are mixed to form magnesium sulfate concentrated water, the magnesium sulfate concentrated water enters a freezing crystallization magnesium sulfate system to produce magnesium sulfate for sale, and the produced freezing crystallization mother liquor enters a mother liquor two-stage nanofiltration membrane to obtain mother liquor fresh water and mother liquor concentrated water; the mother liquid fresh water is mainly a mixed solution of sodium chloride and magnesium salt.
Description
Technical Field
The invention relates to a power plant desulfurization wastewater zero-discharge treatment process and system based on an electrodialysis technology, and belongs to the field of water treatment.
Background
One, introduction the development in this technical field:
the desulfurization waste water is a large amount of SO-containing water produced by coal burning of coal-fired power plants2The flue gas is industrial waste water obtained after being treated by wet desulphurization. In order to maintain the balance of the materials of the slurry circulation system of the desulfurization apparatus, prevent the concentration of the soluble portion, i.e., chlorine, in the flue gas from exceeding a prescribed value and ensure the quality of gypsum, it is necessary to discharge a certain amount of desulfurization waste water from the system, which is mainly from the gypsum dewatering and washing system. The impurities contained in the wastewater mainly comprise suspended matters, supersaturated sulfite, sulfate and heavy metals, and many of the impurities are the first pollutants which are strictly controlled in the national environmental protection standard. According to the specification of the flue gas desulfurization design technical regulation of DL/T5196-2004 thermal power plant, a desulfurization wastewater treatment system is separately arranged in a power plant with desulfurization wastewater, and the desulfurization wastewater can be discharged only after being treated.
The desulfurization wastewater has complex components, has certain influence on equipment pipelines and water structures, and the harm is mainly embodied in the following aspects:
(1) the high-concentration suspended matters seriously affect the turbidity of water, and easily generate scaling phenomenon in equipment and pipelines to influence the operation of a desulfurization device;
(2) the desulfurization wastewater is weakly acidic, heavy metal pollutants have better solubility in the wastewater, and although the content of the heavy metal pollutants is less, the heavy metal pollutants are directly discharged to have a certain toxic effect on aquatic organisms; the high concentration of chloride ions in the wastewater can cause corrosion of equipment and pipelines, and when the concentration reaches a certain degree, the operation and the service life of the absorption tower can be seriously influenced, the desulfurization efficiency can be reduced, and the quality of gypsum can be influenced;
(3) the influence of fluorine ions is similar to that of chlorine ions, but because fluorine can generate calcium fluoride with calcium to precipitate, the content of fluorine ions in the desulfurization wastewater is relatively low, the fluorine ions have influence on the quality of gypsum, the corrosion on a tower body and a pipeline is much smaller than that of chlorine ions, but the fluorine ions and Al in limestone slurry are easy to generate colloidal flocculate which forms a coating film to cover the surface of limestone particles, so that the dissolution of limestone is hindered, and the desulfurization efficiency is influenced;
(4) the high-concentration sulfate in the desulfurization wastewater is directly discharged into an environmental water body, so that the necessary trace metal elements of aquatic plants are lost, and the original ecological function of the water body is changed;
(5) the discharge of a large amount of toxic substances in the desulfurization wastewater can cause pollution to soil and water sources, influence the health of people and animals, and cause chronic poisoning after long-term accumulation.
Although the conventional treatment method of the desulfurization wastewater is mature, the process flow, the construction cost and the operation cost are low, the zero discharge of the wastewater cannot be realized, the application of the desulfurization wastewater zero discharge technology is imperative along with the continuous improvement of the environmental protection requirement, and the reasonable selection of the proper desulfurization wastewater zero discharge technology is crucial to the desulfurization wastewater treatment and zero discharge of a power plant.
Second, the prior art related to the present invention:
1. the traditional treatment process of the desulfurization wastewater mainly comprises chemical treatment, and a treatment system of the desulfurization wastewater can be divided into a wastewater treatment system and a sludge treatment system. The waste water treatment system can be divided into the working procedures of neutralization, sedimentation, flocculation, concentration and clarification.
(1) Neutralizing: adding about 5% lime milk solution into the neutralization tank to increase the pH value of the wastewater to be above 9.0, and most heavy metal ions can generate insoluble hydroxide and precipitate under the environment.
(2) And (3) settling: ca in lime milk while weighting metal ions to form insoluble hydroxide2+Reacting with partial F-in the wastewater to generate indissolvable CaF2Thereby achieving the effect of removing fluorine. But Ca in the neutralized wastewater2+、Hg2+The content of the organic sulfide still exceeds the standard, and based on the content, the organic sulfide is added into a settling tank to be mixed with the residual Ca in the ionic state2+ 、Hg2+React and generate insoluble sulfide to depositTo do so.
(3) Flocculation, wherein the main components of suspended matters in the desulfurization wastewater are gypsum particles and SiO2Hydroxides of Fe and Al. Adding a flocculating agent into the flocculation tank to agglomerate small particles into large particles so as to deposit, and adding Polyacrylamide (PAM) into the inlet of the clarification tank to further strengthen the agglomeration process so that floccules are easier to deposit.
(4) Concentration and clarification: the flocculated effluent enters a clarification tank, flocculate is deposited at the bottom and concentrated into sludge, and the upper part is the system effluent. Most of the sludge is conveyed into the dehydrator by a pump, and a small part of the sludge returns to the neutralization reaction box to provide crystal nuclei required by the formation of the flocculating constituent.
But even after traditional treatment, the produced water of the desulfurization wastewater still has the characteristics of high salt content, high corrosivity and the like.
2. For the desulfurization wastewater zero-discharge process, a multi-effect evaporation crystallization process, an MVR evaporation crystallization process, a high-temperature flue evaporation process and a membrane distillation process are generally available.
(1) The multi-effect evaporation crystallization process is a conventional wastewater zero-discharge treatment method. The evaporation system is divided into 4 units, namely a heat input unit, a heat recovery unit, a crystallization unit and an auxiliary system unit. The heat input unit is connected with steam from the main plant area, the steam is changed into low-pressure steam after temperature and pressure reduction, and then the steam is sent to the heating chamber to heat the wastewater. The condensate after heat exchange enters a condensate tank. And (3) discharging the desulfurization wastewater after conventional treatment, heating and concentrating the wastewater by a multi-stage evaporation chamber, conveying the wastewater to a salt slurry box, conveying the wastewater to a swirler by a salt slurry pump, performing cyclone on large-particle salt crystals, separating salt crystals, and conveying the salt crystals to various drying bed drying towers for drying by a screw conveyor. And returning the slurry separated by the cyclone and the centrifuge to a heating system, evaporating and concentrating, and finally drying out salt crystals, packaging and transporting to leave a factory.
Although the multi-effect evaporation technology is mature, the popularization of the treatment process in the field of zero emission of desulfurization wastewater is limited due to the extremely high energy consumption of the treatment process.
(2) Compared with the multi-effect evaporation crystallization technology, the mechanical vapor recompression technology (MVR evaporator) has the advantage that the energy consumption is reduced.
The evaporator of the evaporation system comprises a horizontal spray horizontal tube film evaporator and a vertical falling film evaporator. The comprehensive horizontal evaporator is not suitable for being used as a wastewater concentration device to treat desulfurization wastewater due to the performance of the comprehensive horizontal evaporator in operation, and the main reasons are as follows: the spray head is difficult to distribute water uniformly and is easy to block. Secondly, the horizontal evaporator has lower heat efficiency, and compared with the vertical falling-film evaporator, the efficiency is reduced by 30 to 50 percent; the vertical falling-film evaporator is mature in application in the aspect of zero emission of desulfurization waste water, and has the advantages of high heat transfer efficiency, material liquid pipe passing and the like.
The crystallizer of the crystallization system generally takes the form of forced circulation + flash tank. The strong brine after the brine is concentrated in the evaporator enters a crystallizer water inlet tank for storage, and is continuously and uniformly stirred. The strong brine directly enters the flash tank under the lifting of the crystallizer water inlet pump. The superheated brine is fed to a flash tank where part of the water is vaporized to form steam.
(3) The desulfurization waste water is sent to a flue behind an air preheater by a waste water pump and is sprayed out by an atomizing nozzle, the desulfurization waste water in an atomized state is evaporated in the flue immediately, impurities in the waste water and fly ash enter dust removal equipment along with flue gas, and after passing through a dust remover, particulate matters are captured and discharged along with the ash. The process separates water and impurities in the desulfurization wastewater by an evaporation method, thereby realizing zero emission of the desulfurization wastewater.
(4) The technical principle of membrane distillation is that one side of the membrane is hot wastewater solution to be treated which is in direct contact with the membrane, and the other side of the membrane is low-temperature cold water, so that water cannot pass through the hydrophobic membrane, but water vapor can pass through the membrane holes due to the steam pressure difference between the two sides of the membrane and is transferred from the high-pressure steam side to the low-pressure steam side, and therefore separation of pollutants and water is achieved. Membrane distillation has been studied more and more in recent years due to its advantages of low operating temperature, small equipment required, low external heat loss, etc., but it basically stays in the laboratory stage because the problems of difficult amplification, difficult latent heat recovery, etc. hinder the industrial application and popularization of membrane distillation.
Although the conventional treatment method of the desulfurization wastewater is mature, the process flow, the construction cost and the operation cost are low, the zero discharge of the wastewater cannot be realized, the application of the desulfurization wastewater zero discharge technology is imperative along with the continuous improvement of the environmental protection requirement, and the reasonable selection of the proper desulfurization wastewater zero discharge technology is crucial to the desulfurization wastewater treatment and zero discharge of a power plant.
In conclusion, after the incoming water is properly softened, the vertical falling-film evaporator and the forced circulation flash tank are adopted to carry out zero emission treatment on the desulfurization wastewater, so that the coal-fired power plant can really realize zero emission of the wastewater, and the sewage discharge is avoided.
However, most of the evaporated crystal salts are NaCl and Na based on the above process2SO4Some of the mixed salts composed of the components are even classified as dangerous wastes, and the disposal cost is high. If a high-purity separation technology is introduced to extract high-purity NaCl salt, the economic benefit of the process can be obviously improved when the NaCl salt is sold as industrial salt.
3. In patent No. CN111170538A, a process and a system for treating desulfurized wastewater are also disclosed. The method comprises the following steps: softening and clarifying the desulfurization wastewater; adding sodium sulfate into the softened and clarified effluent and crystallizing at normal temperature; adding sodium carbonate into the normal-temperature crystallization effluent to obtain softened water effluent and calcium carbonate; performing nanofiltration separation treatment on the softened water to obtain nanofiltration produced water and nanofiltration concentrated water; performing electrodialysis and reverse osmosis coupling concentration treatment on the nanofiltration produced water to obtain electrodialysis concentrated water and reverse osmosis produced water; and carrying out evaporation crystallization on the electrodialysis concentrated water to obtain sodium chloride product salt.
Although the method can effectively treat the desulfurization wastewater, silicon substances always exist in the whole process chain in the process flow, so that the problem of silicon enrichment is easily caused, and irreversible influence is caused on membrane treatment equipment.
Thirdly, the disadvantages of the prior art:
1. although the traditional treatment process for the desulfurization wastewater is mature and has low process flow, construction cost and operation cost, the produced water of the desulfurization wastewater still has the characteristics of high salt content, high corrosivity and the like, and zero discharge of the wastewater cannot be realized.
2. For the desulfurization wastewater zero-discharge process:
(1) the multi-effect evaporation crystallization process comprises the following steps: although the technology is mature, the extremely high energy consumption of the treatment process limits the popularization of the treatment process in the field of zero emission of the desulfurization wastewater.
(2) MVR evaporation crystallization process and exhaust to high temperature flue evaporation process: the obtained crystalline salt is mostly NaCl and Na2SO4Some of the mixed salts composed of the components are even classified as dangerous wastes, and the disposal cost is high.
(3) And (3) membrane distillation process: membrane distillation has been studied more and more in recent years due to its advantages of low operating temperature, small equipment required, low external heat loss, etc., but it basically stays in the laboratory stage because the problems of difficult amplification, difficult latent heat recovery, etc. hinder the industrial application and popularization of membrane distillation.
3. Aiming at the treatment process and the treatment system of the desulfurization wastewater in the patent No. CN 111170538A: although the desulfurization wastewater can be effectively treated to realize zero emission, silicon substances always exist in the whole process chain in the process flow, so that the problem of silicon enrichment is easily caused, and irreversible influence is caused on membrane treatment equipment.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the power plant desulfurization wastewater zero-discharge treatment process based on the electrodialysis technology, which has reasonable structural design.
The technical scheme adopted by the invention for solving the problems is as follows: the power plant desulfurization wastewater zero-discharge treatment process based on the electrodialysis technology comprises the following steps:
the desulfurization wastewater raw water enters a triple box for process treatment, part of heavy metals are completely precipitated in the form of hydroxides by adding lime milk, organic sulfides are added to combine cadmium and mercury heavy metals into sulfides which are insoluble in water, and then a flocculating agent is added to precipitate most of suspended matters and adsorb heavy metal hydroxides;
the effluent of the triple box enters a clarification tank, and a sodium oxalate solution with the concentration of 5 percent is added into the clarification tank to remove the residual Ca2+The supernatant effluent of the clarification tank enters a combined unit to remove suspended matters and reduce COD;
a small part of filtered water is recycled as self-use water of a power plant;
the process treatment of the triple box and the production of precipitated sludge in the clarification tank, the precipitated sludge enters a plate-and-frame filter press for filter pressing, filter pressing effluent flows back to the front end of the triple box and is mixed with the raw desulfurization wastewater to enter the triple box, and the filter-pressed sludge cake is loaded on a truck and sent out for treatment;
the filtered water enters a nanofiltration membrane system to carry out primary salt separation of divalent ions, wherein nanofiltration fresh water and nanofiltration concentrated water are generated;
the nanofiltration fresh water is mainly sodium chloride brine which contains partial magnesium salt, and enters a nanofiltration membrane fresh water tank;
the nanofiltration concentrated water is mainly magnesium sulfate high-concentration salt water and enters a nanofiltration membrane concentrated water tank;
fresh water in the nanofiltration membrane fresh water tank enters a monovalent cation selective electrodialysis system, and the monovalent cation selective electrodialysis system generates two liquids, namely desalted liquid and concentrated liquid;
the desalting solution mainly comprises salt water with most salt and low content of sodium chloride, magnesium salt trapped in the desalting solution by a monovalent cation selective electrodialysis system, and enters an SWRO system after treatment;
the SWRO system generates two liquids of reverse osmosis produced water and reverse osmosis concentrated water;
the reverse osmosis produced water enters a final produced water tank for reuse;
the high-concentration reverse osmosis concentrated water obtained after concentration by the SWRO system is mainly a mixed solution of sodium chloride and magnesium salt and flows back to a nanofiltration membrane concentrated water tank;
the concentrated solution is mainly high-concentration sodium chloride brine, the concentrated solution enters a sodium chloride crystallizer for evaporation and crystallization to obtain pure sodium chloride for sale, and sodium chloride crystallization mother liquor generated in the sodium chloride crystallizer enters a mother liquor flue evaporation system for treatment;
in a nanofiltration membrane concentrated water tank, nanofiltration concentrated water and reverse osmosis concentrated water are mixed to form magnesium sulfate concentrated water, the magnesium sulfate concentrated water enters a freezing crystallization magnesium sulfate system to produce magnesium sulfate for sale, and the produced freezing crystallization mother liquor enters a mother liquor two-stage nanofiltration membrane to obtain mother liquor fresh water and mother liquor concentrated water;
the mother liquor fresh water is mainly a mixed solution of sodium chloride and magnesium salt, flows back to the nanofiltration membrane fresh water tank, is mixed with the nanofiltration fresh water to form fresh water, and enters a monovalent cation selective electrodialysis system;
the mother liquor concentrated water is mixed salt solution of various ions and enters a mother liquor flue evaporation system for treatment.
Further, the recovery rate of the nanofiltration membrane system was 60%.
Further, the recovery rate of the monovalent cation selective electrodialysis system is more than 93%.
Further, SWRO systems were processed at 75% recovery.
Further, the two-stage nanofiltration membrane of the mother liquor is subjected to salt separation treatment according to the recovery rate of 75%.
Further, another technical purpose of the invention is to provide a power plant desulfurization wastewater zero-emission treatment system based on an electrodialysis technology.
The technical purpose of the invention is realized by the following technical scheme.
The utility model provides a desulfurization waste water zero release processing system of power plant based on electrodialysis technique which structural feature lies in: the treatment system is applied to the power plant desulfurization wastewater zero-discharge treatment process based on the electrodialysis technology, and comprises a three-header tank, a clarification tank, a combined unit, a plate-and-frame filter press, a nanofiltration membrane fresh water tank, a nanofiltration membrane system, a nanofiltration membrane concentrated water tank, a frozen crystallized magnesium sulfate system, an SWRO system, a monovalent cation selective electrodialysis system, a sodium chloride crystallizer, a mother liquor flue evaporation system, a mother liquor two-stage nanofiltration membrane and a final product water tank;
the system comprises a triple box, a combined unit, a plate-and-frame filter press, a nanofiltration membrane system, a sodium chloride selective electrodialysis system, a SWRO system, a sodium chloride crystallizer, a final product water tank, a nanofiltration membrane concentrated water tank, a sodium chloride crystallizer, a mother liquor flue evaporation system and a mother liquor two-stage nanofiltration membrane.
Further, the combined unit comprises a sand filtration system, an advanced oxidation system and an ultrafiltration system.
Compared with the prior art, the invention has the following advantages: the desulfurization wastewater of the power plant is effectively solved, zero emission is realized, and energy consumption and investment cost are reduced; sodium oxalate replaces sodium carbonate, so that foreign ions are prevented from being introduced, and pure magnesium sulfate (MgSO)4) Salt, obtaining income; the combined process of the nanofiltration membrane system, the monovalent cation selective electrodialysis system and the SWRO system is used, so that magnesium salts can be further recovered, and pure sodium chloride (NaCl) salts can be obtained to obtain income; by using the monovalent cation selective electrodialysis system, the sodium chloride concentrated water with the salt content concentration of 18-20 ten thousand mg/L can be obtained, the concentrated water amount is small, and the investment scale of a sodium chloride crystallizer can be greatly reduced; in addition, the problem of silicon enrichment in the system can be effectively solved in the evaporation system of the mother liquor flue.
Drawings
Fig. 1 is a schematic structural diagram of a power plant desulfurization wastewater zero-discharge treatment system based on an electrodialysis technology.
Description of reference numerals: the device comprises a triple box A, a clarification tank B, a combination unit C, a plate-and-frame filter press D, a nanofiltration membrane fresh water tank E, a nanofiltration membrane system F, a nanofiltration membrane concentrated water tank G, a frozen crystalline magnesium sulfate system H, SWRO system I, a monovalent cation selective electrodialysis system J, a sodium chloride crystallizer K, a mother liquor flue evaporation system L, a mother liquor two-stage nanofiltration membrane M and a final product water tank N.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
Examples are given.
Referring to fig. 1, it should be understood that the structures, ratios, sizes, and the like shown in the drawings are only used for understanding and reading the disclosure, and are not used for limiting the conditions that the present invention can be implemented, so they have no technical essence, and any structural modifications, ratio changes or size adjustments should fall within the scope of the present invention without affecting the function and the achievable purpose of the present invention. In the present specification, the terms "upper", "lower", "left", "right", "middle" and "one" are used for clarity of description, and are not used to limit the scope of the present invention, and the relative relationship between the terms and the relative positions may be changed or adjusted without substantial technical changes.
The power plant desulfurization wastewater zero-discharge treatment process based on the electrodialysis technology in the embodiment comprises the following steps:
the raw water of the desulfurization waste water enters a traditional triple box A for process treatment, and lime milk (Ca (0H) is added2Calcium hydroxide) to make partial heavy metal completely precipitate in the form of hydroxide, then adding organic sulfide to make heavy metal of cadmium and mercury combine into sulfide which is difficult to dissolve in water, then adding flocculant to make most suspended substance precipitate and adsorbing heavy metal hydroxide precipitate.
Then, the effluent of the triple box A enters a clarification tank B, and a sodium oxalate solution with the concentration of 5% is added into the clarification tank B to further remove the residual Ca2+And then, the supernatant of the clarification tank B flows into a combination unit C to further remove suspended matters and reduce COD.
A small part of filtered water is recycled as self-use water of a power plant.
Precipitated sludge is generated in the process treatment of the triple box A and the clarification tank B, then the precipitated sludge enters a plate-and-frame filter press D for filter pressing, filter pressing effluent flows back to the front end of the triple box A to be mixed with the raw desulfurization wastewater to enter the triple box A, and the filter-pressed sludge cake is loaded on a truck and sent out for treatment.
The filtered water enters a nanofiltration membrane system F to carry out primary salt separation of divalent ions, and at the moment, the recovery rate of the nanofiltration membrane system F is 60%, wherein nanofiltration fresh water and nanofiltration concentrated water can be generated.
The nanofiltration fresh water is mainly sodium chloride (NaCl) salt water containing partial magnesium salts, and then enters a nanofiltration membrane fresh water tank E.
The nanofiltration concentrated water is mainly magnesium sulfate (MgSO)4) The high-concentration brine then enters a nanofiltration membrane concentrated water tank G.
Fresh water in the nanofiltration membrane fresh water tank E enters a monovalent cation selective electrodialysis system J, the recovery rate of the system is over 93 percent, and the monovalent cation selective electrodialysis system J can generate two liquids, namely desalted liquid and concentrated liquid.
The desalted solution mainly removes most of salt sodium chloride (NaCl) low-content brine, and also contains magnesium salts trapped in the desalted solution by a monovalent cation selective electrodialysis system J, and then the desalted solution enters an SWRO system I (reverse osmosis) to be treated according to 75% of recovery rate, and the SWRO system I generates two liquids of reverse osmosis produced water and reverse osmosis concentrated water.
And the reverse osmosis produced water enters a final produced water tank N for reutilization.
The high-concentration reverse osmosis concentrated water obtained after concentration by the SWRO system I (reverse osmosis) is mainly a mixed solution of sodium chloride (NaCl) and magnesium salt, and flows back to the nanofiltration membrane concentrated water tank G.
The concentrated solution is mainly high-concentration sodium chloride (NaCl) brine, then the concentrated solution enters a sodium chloride crystallizer K for evaporation and crystallization to obtain pure sodium chloride (NaCl) salt for sale, and sodium chloride crystallization mother liquor generated in the sodium chloride crystallizer K enters a mother liquor flue evaporation system L for treatment.
In a nanofiltration membrane concentrated water tank G, nanofiltration concentrated water and reverse osmosis concentrated water are mixed to form magnesium sulfate concentrated water, the magnesium sulfate concentrated water enters a freezing crystallization magnesium sulfate system H, and magnesium sulfate (MgSO)4) The salt is sold, and the generated freezing crystallization mother liquor enters a mother liquor two-stage nanofiltration membrane M, and the concentration of the freezing crystallization mother liquor is 75 percentThe recovery rate is subjected to salt separation treatment to obtain mother liquor fresh water and mother liquor concentrated water.
The mother liquor fresh water is mainly a mixed solution of sodium chloride (NaCl) and magnesium salts, flows back to the nanofiltration membrane fresh water tank E, is mixed with the nanofiltration fresh water to form fresh water, and enters the monovalent cation selective electrodialysis system J.
The mother liquor concentrated water is mixed salt solution of various ions and enters a mother liquor flue evaporation system L for treatment.
The power plant desulfurization wastewater zero-discharge treatment system based on the electrodialysis technology in the embodiment is applied to a power plant desulfurization wastewater zero-discharge treatment process based on the electrodialysis technology.
The power plant desulfurization wastewater zero-discharge treatment system based on the electrodialysis technology in the embodiment comprises a triple box A, a clarification tank B, a combination unit C, a plate-and-frame filter press D, a nanofiltration membrane fresh water tank E, a nanofiltration membrane system F, a nanofiltration membrane concentrated water tank G, a frozen crystallized magnesium sulfate system H, SWRO system I, a monovalent cation selective electrodialysis system J, a sodium chloride crystallizer K, a mother liquor flue evaporation system L, a mother liquor two-stage nanofiltration membrane M and a final product water tank N; the combined unit C comprises a sand filtration system, an advanced oxidation system and an ultrafiltration system, and has a sand filtration function, an advanced oxidation function and an ultrafiltration function.
The triple box A is connected with the clarification tank B, the clarification tank B is connected with a combined unit C and a plate-and-frame filter press D, the plate-and-frame filter press D is connected with the triple box A, the combined unit C is connected with a nanofiltration membrane system F, the nanofiltration membrane system F is connected with a nanofiltration membrane fresh water tank E and a nanofiltration membrane concentrated water tank G, the nanofiltration membrane concentrated water tank G is connected with a frozen crystalline magnesium sulfate system H, the frozen crystalline magnesium sulfate system H is connected with a mother liquor two-stage nanofiltration membrane M, the nanofiltration membrane fresh water tank E is connected with a monovalent cation selective electrodialysis system J, the monovalent cation selective electrodialysis system J is connected with a SWRO system I and a sodium chloride crystallizer K, the SWRO system I is connected with a final product water tank N and the nanofiltration membrane concentrated water tank G, and the sodium chloride crystallizer K and the mother liquor flue two-stage nanofiltration membrane M are connected with a mother liquor flue evaporation system L.
1. In the application, the process and the system are adopted to treat the desulfurization wastewater, zero emission is realized, and byproducts, namely salt, are produced, and the income is produced in sale.
2. In this application, 5% strength organic solution of sodium oxalate solution is used for Ca2+Further removing, filtering and reducing COD (organic matter) by a combined unit C of sand filtration, advanced oxidation and ultrafiltration, and avoiding external ions from entering the next system.
3. In this application, monovalent cation selectivity electrodialysis system J, its electrodialysis equipment chooses ordinary anion exchange membrane and monovalent selectivity cation exchange membrane combination mode for use, after intercepting the magnesium ion in the fresh water in the desalination liquid, get into SWRO system I (reverse osmosis) further concentration, obtain the concentrated water of reverse osmosis, mix with the concentrated water of receiving nanofiltration afterwards and obtain the magnesium sulfate dense water, get into freezing crystallization magnesium sulfate system H, realized the further recovery of magnesium ion, and can obtain pure sodium chloride (NaCl) salt.
4. In the application, mother liquor fresh water flows back to the nanofiltration membrane fresh water tank E in the mother liquor two-stage nanofiltration membrane M, forms fresh water after being mixed with the nanofiltration fresh water, enters the monovalent cation selective electrodialysis system J, and realizes further recovery of sodium chloride (NaCl) salt.
5. In the application, the mother liquor flue evaporation system L is arranged, so that the problem of silicon enrichment in the whole process flow is effectively solved.
In addition, it should be noted that the specific embodiments described in the present specification may be different in the components, the shapes of the components, the names of the components, and the like, and the above description is only an illustration of the structure of the present invention. Equivalent or simple changes in the structure, characteristics and principles of the invention are included in the protection scope of the patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (7)
1. A power plant desulfurization wastewater zero-discharge treatment process based on an electrodialysis technology is characterized in that: the treatment process comprises the following steps:
the raw water of the desulfurization wastewater enters a triple box (A) for process treatment, part of heavy metals are completely precipitated in the form of hydroxides by adding lime milk, organic sulfides are added to combine cadmium and mercury heavy metals into sulfides which are insoluble in water, and then a flocculating agent is added to precipitate most suspended matters and adsorb heavy metal hydroxides to precipitate;
the effluent of the three-header tank (A) enters a clarification tank (B), and a sodium oxalate solution with the concentration of 5 percent is added into the clarification tank (B) to remove residual Ca2 +The supernatant effluent of the clarification tank (B) enters a combined unit (C) to remove suspended matters and reduce COD;
a small part of filtered water is recycled as self-use water of a power plant;
the process treatment of the triple box (A) and the sedimentation sludge generated in the clarification tank (B) enter a plate-and-frame filter press (D) for filter pressing, filter pressing effluent flows back to the front end of the triple box (A) to be mixed with the raw desulfurization wastewater and enter the triple box (A), and the filter-pressed sludge cake is loaded on a vehicle and sent out for treatment;
the filtered water enters a nanofiltration membrane system (F) to carry out primary salt separation of divalent ions, wherein nanofiltration fresh water and nanofiltration concentrated water are generated;
the nanofiltration fresh water is mainly sodium chloride brine which contains partial magnesium salt, and enters a nanofiltration membrane fresh water tank (E);
the nanofiltration concentrated water is mainly magnesium sulfate high-concentration salt water and enters a nanofiltration membrane concentrated water tank (G);
fresh water in the nanofiltration membrane fresh water tank (E) enters a monovalent cation selective electrodialysis system (J), and the monovalent cation selective electrodialysis system (J) generates two liquids of desalted liquid and concentrated liquid;
the desalted solution mainly removes most of salt brine with low content of sodium chloride, and also contains magnesium salt trapped in the desalted solution by a monovalent cation selective electrodialysis system (J), and enters an SWRO system (I) after treatment;
the SWRO system (I) generates two liquids of reverse osmosis produced water and reverse osmosis concentrated water;
the reverse osmosis produced water enters a final produced water tank (N) for reutilization;
the high-concentration reverse osmosis concentrated water obtained after concentration by the SWRO system (I) is mainly a mixed solution of sodium chloride and magnesium salt and flows back to a nanofiltration membrane concentrated water tank (G);
the concentrated solution is mainly high-concentration sodium chloride brine, the concentrated solution enters a sodium chloride crystallizer (K) for evaporation and crystallization to obtain pure sodium chloride for sale, and sodium chloride crystallization mother liquor generated in the sodium chloride crystallizer (K) enters a mother liquor flue evaporation system (L) for treatment;
in a nanofiltration membrane concentrated water tank (G), nanofiltration concentrated water and reverse osmosis concentrated water are mixed to form magnesium sulfate concentrated water, the magnesium sulfate concentrated water enters a freezing crystallization magnesium sulfate system (H) to generate magnesium sulfate for sale, and the generated freezing crystallization mother liquor enters a mother liquor two-stage nanofiltration membrane (M) to obtain mother liquor fresh water and mother liquor concentrated water;
the mother liquor fresh water is mainly a mixed solution of sodium chloride and magnesium salts, flows back to the nanofiltration membrane fresh water tank (E), is mixed with the nanofiltration fresh water to form fresh water, and enters the monovalent cation selective electrodialysis system (J);
the mother liquor concentrated water is mixed salt solution of various ions and enters a mother liquor flue evaporation system (L) for treatment.
2. The power plant desulfurization wastewater zero-emission treatment process based on the electrodialysis technology as claimed in claim 1, is characterized in that: the recovery rate of the nanofiltration membrane system (F) was 60%.
3. The power plant desulfurization wastewater zero-emission treatment process based on the electrodialysis technology as claimed in claim 1, is characterized in that: the recovery rate of the monovalent cation selective electrodialysis system (J) is more than 93 percent.
4. The power plant desulfurization wastewater zero-emission treatment process based on the electrodialysis technology as claimed in claim 1, is characterized in that: the SWRO system (I) was processed at 75% recovery.
5. The power plant desulfurization wastewater zero-emission treatment process based on the electrodialysis technology as claimed in claim 1, is characterized in that: and carrying out salt separation treatment on the mother liquor two-stage nanofiltration membrane (M) according to the recovery rate of 75%.
6. The utility model provides a desulfurization waste water zero release processing system of power plant based on electrodialysis technique which characterized in that: the treatment system is applied to the power plant desulfurization wastewater zero-emission treatment process based on the electrodialysis technology, which is characterized in that the treatment system comprises a three-header (A), a clarification tank (B), a combined unit (C), a plate-and-frame filter press (D), a nanofiltration membrane fresh water tank (E), a nanofiltration membrane system (F), a nanofiltration membrane concentrated water tank (G), a frozen crystalline magnesium sulfate system (H), a SWRO system (I), a monovalent cation selective electrodialysis system (J), a sodium chloride crystallizer (K), a mother liquor flue evaporation system (L), a mother liquor two-stage nanofiltration membrane (M) and a final product water tank (N);
the three-header tank (A) is connected with a clarification tank (B), the clarification tank (B) is connected with a combined unit (C) and a plate-and-frame filter press (D), the plate-and-frame filter press (D) is connected with the three-header tank (A), the combined unit (C) is connected with a nanofiltration membrane system (F), the nanofiltration membrane system (F) is connected with a nanofiltration membrane fresh water tank (E) and a nanofiltration membrane concentrated water tank (G), the nanofiltration membrane concentrated water tank (G) is connected with a frozen crystalline magnesium sulfate system (H), the frozen crystalline magnesium sulfate system (H) is connected with a mother liquor two-stage nanofiltration membrane (M), the nanofiltration membrane fresh water tank (E) is connected with a monovalent cation selective electrodialysis system (J), the monovalent cation selective electrodialysis system (J) is connected with a SWRO system (I) and a sodium chloride crystallizer (K), and the RO system (I) is connected with a final product water tank (N) and the nanofiltration membrane concentrated water tank (G), the sodium chloride crystallizer (K) and the mother liquor two-stage nanofiltration membrane (M) are connected with a mother liquor flue evaporation system (L).
7. The power plant desulfurization wastewater zero-emission treatment system based on the electrodialysis technology as claimed in claim 6, characterized in that: the combined unit (C) comprises a sand filtration system, an advanced oxidation system and an ultrafiltration system.
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| CN114605009A (en) * | 2022-03-11 | 2022-06-10 | 佛山市佳利达环保科技股份有限公司 | Sodium chloride recovery zero-emission treatment method for printing and dyeing wastewater treatment |
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| CN115072753B (en) * | 2022-07-02 | 2023-05-19 | 山东海化集团有限公司 | Method for preparing magnesium sulfate heptahydrate and sodium chloride |
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