CN115572004A - System and method for removing heavy metals from fly ash washing liquid by coupling flue gas purification with waste incineration plant - Google Patents
System and method for removing heavy metals from fly ash washing liquid by coupling flue gas purification with waste incineration plant Download PDFInfo
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- CN115572004A CN115572004A CN202211165974.6A CN202211165974A CN115572004A CN 115572004 A CN115572004 A CN 115572004A CN 202211165974 A CN202211165974 A CN 202211165974A CN 115572004 A CN115572004 A CN 115572004A
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- 238000005406 washing Methods 0.000 title claims abstract description 93
- 239000007788 liquid Substances 0.000 title claims abstract description 74
- 239000010881 fly ash Substances 0.000 title claims abstract description 73
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 73
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 239000003546 flue gas Substances 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000004056 waste incineration Methods 0.000 title claims abstract description 18
- 238000000746 purification Methods 0.000 title claims abstract description 16
- 230000008878 coupling Effects 0.000 title claims abstract description 11
- 238000010168 coupling process Methods 0.000 title claims abstract description 11
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 11
- 238000006298 dechlorination reaction Methods 0.000 claims abstract description 35
- 150000003839 salts Chemical class 0.000 claims abstract description 35
- 230000018044 dehydration Effects 0.000 claims abstract description 34
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 34
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 32
- 230000015556 catabolic process Effects 0.000 claims abstract description 31
- 238000006731 degradation reaction Methods 0.000 claims abstract description 31
- 238000001704 evaporation Methods 0.000 claims abstract description 30
- 238000000926 separation method Methods 0.000 claims abstract description 27
- 230000008020 evaporation Effects 0.000 claims abstract description 24
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 20
- 239000002956 ash Substances 0.000 claims abstract description 18
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 16
- 239000001103 potassium chloride Substances 0.000 claims abstract description 16
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000011780 sodium chloride Substances 0.000 claims abstract description 10
- 238000002425 crystallisation Methods 0.000 claims abstract description 7
- 230000008025 crystallization Effects 0.000 claims abstract description 7
- 238000003795 desorption Methods 0.000 claims abstract 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 56
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 239000011734 sodium Substances 0.000 claims description 17
- 239000002893 slag Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 13
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 12
- 239000011575 calcium Substances 0.000 claims description 12
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 10
- 229910001424 calcium ion Inorganic materials 0.000 claims description 10
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 239000013043 chemical agent Substances 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 6
- 239000003814 drug Substances 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000011777 magnesium Substances 0.000 claims description 4
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 239000012466 permeate Substances 0.000 claims description 4
- 239000000779 smoke Substances 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 3
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- 238000007599 discharging Methods 0.000 claims description 2
- 150000002736 metal compounds Chemical class 0.000 claims description 2
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- 239000007789 gas Substances 0.000 claims 1
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- 239000003344 environmental pollutant Substances 0.000 description 5
- 231100000719 pollutant Toxicity 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 4
- 239000005431 greenhouse gas Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000006641 stabilisation Effects 0.000 description 3
- 238000011105 stabilization Methods 0.000 description 3
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- 239000010426 asphalt Substances 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- -1 alcohol amine Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000000382 dechlorinating effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- 239000000945 filler Substances 0.000 description 1
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- 150000003071 polychlorinated biphenyls Chemical group 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- 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
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/005—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by heat treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/62—Carbon oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/20—Halogens or halogen compounds
- B01D2257/206—Organic halogen compounds
- B01D2257/2064—Chlorine
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/50—Carbon oxides
- B01D2257/504—Carbon dioxide
-
- 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
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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
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
-
- 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
- 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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- Engineering & Computer Science (AREA)
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- Thermal Sciences (AREA)
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- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to a system and a method for removing heavy metals from fly ash washing liquid by coupling flue gas purification in a waste incineration plant, which comprises a low-temperature thermal degradation unit, a washing dechlorination unit, a carbonation fixed heavy metal unit, a decalcification unit, a centrifugal dehydration unit and an evaporation salt separation unit which are sequentially connected; the low-temperature thermal degradation unit is used for removing dioxin, the washing dechlorination unit is used for carrying out the washing dechlorination to the flying ash, the fixed heavy metal unit of carbonation is used for handling desorption heavy metal to the washing liquid carbonation, the decalcification unit is used for carrying out the decalcification to the washing liquid that handles desorption heavy metal with the carbonation in the last device, the centrifugal dehydration unit is used for carrying out solid-liquid separation with the washing liquid that last step decalcification unit produced, the evaporation divides the washing liquid that salt unit got into in last step to carry out the evaporation crystallization and divides salt, obtain sodium chloride and potassium chloride.
Description
Technical Field
The invention belongs to the field of treatment of fly ash generated by burning household garbage, and relates to a system and a method for removing heavy metals from fly ash washing liquid by coupling flue gas purification in a garbage burning plant.
Background
The incineration fly ash is a powdery substance which is collected in a flue gas pipeline, a flue gas purification device, a separator, a dust remover device and the like in the waste incineration process and has light volume weight and small particle size. The fly ash is classified as solid dangerous waste (code HW 18) by the country because the fly ash contains heavy metals with high leaching toxicity, soluble salts and organic chlorides (polychlorinated biphenyl and dioxin). The incineration fly ash needs to be subjected to multistage washing dechlorination, and then enters a cement kiln or is subjected to resource utilization, wherein the fly ash washing liquid has the characteristics of high pH value, high chlorine, high calcium, high heavy metal concentration and the like, and if the fly ash washing liquid is directly discharged, the environment is seriously polluted. At present, the fly ash water washing liquid is treated mainly by adopting the processes of heavy metal removal, decalcification, multi-stage filtration, pH adjustment and evaporative crystallization salt separation in the industry, and finally sodium chloride and potassium chloride are obtained, wherein the physicochemical property of the sodium salt can reach the secondary standard of sun-dried industrial salt in Industrial salt (GB/T5462-2015), and the potassium chloride meets the standard of II (agricultural potassium chloride) qualified products in Potassium chloride GB 6549-2011.
At present, the heavy metals in the fly ash washing liquid are removed mainly by adopting a chemical agent method, and Na is generally used 2 S、Na 2 SO 4 、Na 2 CO 3 ， NaH 2 PO 4 And the like. The method has the problems of large medicament dosage, high input cost, easy generation of secondary pollution and the like, and simultaneously, the increase of ion species in the evaporative crystallization liquid restricts the purity of subsequent salt production.
On the other hand, with the improvement of national requirements for environmental protection, the flue gas emission standard of a waste incineration plant is more strict, and the requirement is to gradually realize the ultralow emission of pollutants, however, the existing ultralow emission process of atmospheric pollutants has the defects of low technical maturity, large initial investment, high operating cost, complex process and the like. Meanwhile, the nation highly pays attention to the emission reduction work of greenhouse gases such as carbon dioxide and the like. At present, the flue gas CO 2 The trapping mainly adopts a chemical absorption method, the flue gas enters an absorption tower through devices such as denitration, desulfurization, dust removal and the like, and alcohol amine aqueous solution is used as an absorbent to absorb CO 2 The rich solution enters a regeneration tower to be boiled, CO is resolved 2 The whole process is complex and the cost is extremely high. Therefore, it is urgent to find a low-cost and efficient technology for reducing the emission of atmospheric pollutants and carbon dioxide.
Disclosure of Invention
In view of this, the present invention aims to provide a system and a method for removing heavy metals from fly ash washing liquid coupling with flue gas purification in a waste incineration plant, which have low cost and high efficiency.
In order to achieve the purpose, the invention provides the following technical scheme:
a heavy metal removal system for flue gas purification coupling fly ash washing liquid of a waste incineration plant comprises a low-temperature thermal degradation unit, a water washing dechlorination unit, a carbonation fixed heavy metal unit, a decalcification unit, a centrifugal dehydration unit and an evaporation salt separation unit which are sequentially connected;
the low-temperature thermal degradation unit is used for removing dioxin and is provided with an incineration fly ash inlet and a fly ash outlet, and the fly ash outlet of the low-temperature thermal degradation unit is connected with the fly ash inlet of the washing dechlorination unit;
the water washing dechlorination unit is used for carrying out water washing dechlorination on the fly ash, the water washing dechlorination unit comprises an inlet for water and an outlet for ash, the water washing dechlorination unit is also provided with a water washing liquid outlet, and the water washing liquid outlet of the water washing dechlorination unit is connected with the inlet of the carbonation fixed heavy metal unit;
the carbonation fixing heavy metal unit is used for removing heavy metals from the washing liquid through carbonation treatment, an outlet of the carbonation fixing heavy metal unit is connected with an inlet of the decalcification unit, and the carbonation fixing heavy metal unit is also provided with a flue gas inlet;
the decalcification unit is used for decalcification of the rinsing liquid which is used for removing heavy metals in the previous device by carbonation treatment, an outlet of the decalcification unit is connected with an inlet of the centrifugal dehydration unit, and the decalcification unit is also provided with a medicament inlet;
the centrifugal dehydration unit is used for carrying out solid-liquid separation on the mixed liquid generated by the decalcification unit in the last step, and also comprises a solid slag outlet, the solid separated by the centrifugal dehydration unit is discharged from the solid slag outlet, and the outlet of the centrifugal dehydration unit is connected with the inlet of the evaporation salt separation unit;
the evaporation salt separation unit also comprises an outlet, and the evaporation salt separation unit carries out evaporation crystallization salt separation on the permeate liquid entering in the last step to obtain sodium chloride and potassium chloride.
A method for removing heavy metals from fly ash washing liquid by coupling flue gas purification of a waste incineration plant comprises the following steps:
s1: performing low-temperature thermal degradation on the fly ash in a low-temperature thermal degradation unit to remove dioxin;
s2: the fly ash is subjected to water washing dechlorination, the fly ash treated by the low-temperature thermal degradation unit enters a water washing dechlorination unit, water is added into the water washing dechlorination unit, chloride ions, heavy metal ions, calcium and magnesium ions and the like in the fly ash are dissolved into an aqueous solution, and the treated fly ash is discharged from an ash residue outlet;
s3: carrying out carbonation treatment on the water washing liquid to remove heavy metals, introducing the water washing liquid in the previous step into a carbonation fixed heavy metal unit, introducing flue gas containing carbon dioxide into the carbonation fixed heavy metal unit, and carrying out complex chemical reaction on the carbon dioxide and the water washing liquid to generate stable heavy metal compounds;
s4: deep decalcification and magnesium removal by chemical softening method, adding Na into decalcification unit 2 CO 3 、Na 2 SO 4 The calcium and magnesium ions are thoroughly removed by chemical agents;
s5: performing centrifugal dehydration for solid-liquid separation, allowing the mixed liquid from the decalcification unit to enter a centrifugal dehydration unit for solid-liquid separation, and directly discharging the separated solid slag;
s6: and (3) evaporating, crystallizing and separating salt, wherein an evaporation and salt separation unit is used for evaporating and crystallizing the permeate from the centrifugal dehydration unit so as to obtain sodium chloride and potassium chloride.
Further, in step S1, the thermal degradation temperature is 350-450 ℃, and the thermal degradation time is 60-120 minutes.
Further, in step S2, the mass ratio of fly ash to water is 1:1 to 1:5, the water washing time is 15-60 min, the stirring frequency is 60-300 r/min, and the water content of the ash residue after centrifugal dehydration is 40-50%.
Further, in step S3, the proportion of the original fly ash to the flue gas in the carbonation fixed heavy metal unit is 1: the smoke is introduced into the reactor at 250 to 1250 ℃ and the duration of the carbonation treatment is controlled to be 0.2 to 1 hour.
Further, the smoke components comprise CO 2 、SO 2 、NO x HCl, wherein CO 2 8-12% of SO 2 The content is 0.1-80 mg/m 3 ，NO x The content is 0.1-250 mg/m 3 The HCl content is 0.1-50 mg/m 3 。
Further, in step S4, na 2 CO 3 、Na 2 SO 4 The adding amount is 7-12% of the original fly ash.
The invention has the beneficial effects that:
the method combines the heavy metal solidification of the fly ash washing liquid and the flue gas purification of a waste incineration plant, removes the heavy metals in the washing liquid by using the carbon dioxide in the flue gas, and thoroughly removes the heavy metals in the washing liquid, can replace chemical agents, reduces the treatment cost of the washing liquid, and reduces secondary pollution;
the incineration fly ash water washing liquid is strong alkaline and can absorb part of SO in the flue gas discharged by a waste incineration plant 2 Atmospheric pollutants such as NOx and HCl, and CO 2 And greenhouse gases are used, the emission of atmospheric pollutants and greenhouse gases is reduced, and the pollution to the environment is reduced. The method has the advantages of simple process, low investment and low operation cost.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof.
Drawings
For a better understanding of the objects, aspects and advantages of the present invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a process flow diagram of the invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Referring to fig. 1, a system for removing heavy metals from flue gas purification coupling fly ash water washing liquid in a waste incineration plant includes a low-temperature thermal degradation unit, a water washing dechlorination unit, a carbonation fixed heavy metal unit, a decalcification unit, a centrifugal dehydration unit and an evaporation salt separation unit, which are connected in sequence.
The low-temperature thermal degradation unit is used for removing dioxin and comprises a low-temperature thermal degradation device, the low-temperature thermal degradation unit is provided with an incineration fly ash inlet and a fly ash outlet, and the fly ash outlet of the low-temperature thermal degradation unit is connected with the fly ash inlet of the washing dechlorination unit.
The washing dechlorination unit is used for washing dechlorination to the flying ash, and the washing dechlorination unit includes washing dewatering device, and the washing dechlorination unit still includes the import of water and the export of lime-ash. The washing dechlorination unit is also provided with a washing liquid outlet, and the washing liquid outlet of the washing dechlorination unit is connected with the inlet of the carbonation fixed heavy metal unit.
The carbonation fixing heavy metal unit is used for removing heavy metals from the washing liquid through carbonation treatment, and comprises a carbonation fixing heavy metal device. The outlet of the carbonation heavy metal fixing unit is connected with the inlet of the decalcification unit, and the carbonation heavy metal fixing unit is also provided with a flue gas inlet.
The decalcification unit comprises a decalcification device and is used for decalcification of the rinsing liquid which is used for removing heavy metal in the previous device by carbonation treatment. The outlet of the decalcification unit is connected with the inlet of the centrifugal dehydration unit, and the decalcification unit is also provided with a medicament inlet.
The centrifugal dehydration unit is used for carrying out solid-liquid separation on the mixed liquid generated by the last-step decalcification unit, comprises a centrifugal dehydration device and a solid slag outlet, and the solid separated by the centrifugal dehydration unit is discharged from the solid slag outlet. The liquid outlet of the centrifugal dehydration unit is connected with the inlet of the evaporation salt separating unit.
The evaporation salt separating unit further comprises an outlet, the evaporation salt separating unit comprises an evaporation salt separating device, and the evaporation salt separating unit carries out evaporation crystallization salt separation on the water washing liquid entering in the last step to obtain sodium chloride and potassium chloride.
The method mainly comprises the following steps:
s1, removing dioxin through low-temperature thermal degradation of fly ash: wherein, the incineration fly ash enters a low-temperature thermal degradation unit for low-temperature thermal degradation treatment to remove dioxin, preferably, the thermal degradation temperature is 350-450 ℃, and the thermal degradation time is 60-120 minutes;
s2, washing and dechlorinating fly ash: the fly ash treated by the low-temperature thermal degradation unit enters a washing dechlorination unit, water is added into the washing dechlorination unit, chloride ions, heavy metal ions, calcium and magnesium ions and the like in the fly ash are dissolved in an aqueous solution, and ash residues in the aqueous solution are discharged from an ash residue outlet. Heavy metal fixation and stabilization treatment are carried out on the ash slag treated by the washing dechlorination unit, and then the ash slag can be used as raw materials for producing baking-free bricks, fillers for highway asphalt pavement construction, fine aggregates for stabilizing pavement base layers and the like for resource utilization.
Preferably, the mass ratio of the fly ash to the water is 1:1 to 1:5, the water washing time is 15-60 min, and the stirring frequency is 60-300 r/min. The water content of ash after centrifugal dehydration is 40-50%.
S3, carrying out carbonation treatment on the washing liquid to remove heavy metals: introducing flue gas containing carbon dioxide into a carbonation fixed heavy metal unit, wherein the carbon dioxide is absorbed by an alkaline solution and undergoes a complex chemical reaction, so that the stabilization of heavy metal ions is realized, and part of calcium and magnesium ions are removed;
in the carbonation fixed heavy metal unit, the proportion of original fly ash to flue gas is 1: 250-1250 (1 t of original fly ash corresponds to 250-1250 Nm 3 H flue gas) into the flue gas, wherein the flue gas component is CO 2 、SO 2 NOx, HCl, etc., CO 2 8-12% of SO 2 The content is 0.1-80 mg/m 3 The content of NOx is 0.1-250 mg/m 3 The HCl content is 0.1-50 mg/m 3 . The carbonation treatment time is controlled to be 0.2 to 1 hour.
S4, deep decalcification and magnesium removal by a medicament softening method: the water washing liquid from the water washing dehydration unit is carbonated to remove a part of calcium and magnesium ions, and the rest is added with Na in the decalcification unit 2 CO 3 、Na 2 SO 4 The chemical agents are thoroughly removed. Preferably, na 2 CO 3 、Na 2 SO 4 The adding amount is 7-12% of the original fly ash.
S5, carrying out centrifugal dehydration for solid-liquid separation: the mixed liquid from the decalcification unit enters a centrifugal dehydration unit for centrifugal dehydration to carry out solid-liquid separation, and the separated solid slag is directly discharged.
S6, evaporating, crystallizing and separating salt: and the evaporation salt separation unit is used for carrying out evaporation crystallization on the permeation liquid from the centrifugal dehydration unit so as to obtain sodium chloride and potassium chloride, and the obtained sodium chloride and potassium chloride can be used as a snow melting agent, a leather factory raw material, a printing and dyeing factory raw material, a chemical raw material and the like for resource utilization.
The physicochemical property of the separated sodium salt can reach the secondary standard of sun-cured industrial salt in Industrial salt (GB/T5462-2015), and the potassium chloride meets the standard of II (agricultural potassium chloride) qualified products in potassium chloride (GB 6549-2011).
The first embodiment of the invention is as follows:
removing dioxin by low-temperature thermal degradation of fly ash; wherein the thermal degradation temperature is 400 ℃ and the thermal degradation time is 60 minutes.
The fly ash is washed and dechlorinated, chloride ions, heavy metal ions, calcium and magnesium ions and the like in the fly ash are dissolved in an aqueous solution, heavy metal fixation and stabilization treatment are carried out on ash slag after washing treatment, and then the ash slag can be used as raw materials for producing baking-free bricks, filling materials for highway asphalt pavement construction, fine aggregates for stabilizing pavement base courses and the like for resource utilization.
Wherein the mass ratio of the fly ash to the water is 1:3, the water washing time is 30min, and the stirring frequency is 300r/min. The water content of the ash after centrifugal dehydration is 45%.
The washing liquid is carbonated to remove heavy metals, the flue gas containing carbon dioxide is introduced into a carbonation fixed heavy metal unit, the carbon dioxide is absorbed by alkaline solution and generates complex chemical reaction to fix the heavy metals in the washing ash water and remove part of calcium and magnesium ions;
in the carbonation fixed heavy metal unit, the proportion of original fly ash to flue gas is 1:500 (1 t original fly ash corresponds to 500Nm 3 H flue gas) into the flue gas, wherein the flue gas component is CO 2 、SO 2 NOx, HCl, etc., CO 2 Content of 10% SO 2 The content is 18mg/m 3 The NOx content is 175mg/m 3 The HCl content is 5.0mg/m 3 . The carbonation treatment time was controlled at 0.5 hours. The leaching concentration of heavy metals in the water washing liquid of the fly ash after the carbonation treatment is lower than 1mg/L, and SO in the flue gas 2 The concentration of NOx and HCl is reduced to 0.8mg/m 3 、135mg/m 3 、0.6mg/m 3 CO in flue gas 2 The temperature is reduced to 7 percent.
Deeply removing calcium and magnesium by softening with medicinal agent, removing part of calcium and magnesium ions by carbonation treatment of water washing solution, and adding Na into the rest 2 CO 3 、Na 2 SO 4 And chemical agents are thoroughly removed, and solid-liquid separation is carried out by centrifugal dehydration. Na (Na) 2 CO 3 、Na 2 SO 4 The addition amount is 9% of the original fly ash.
Evaporating, crystallizing and separating salt to obtain sodium chloride and potassium chloride.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (7)
1. The utility model provides a waste incineration factory gas cleaning coupling flying dust washing liquid heavy metal desorption system which characterized in that: the device comprises a low-temperature thermal degradation unit, a water washing dechlorination unit, a carbonation fixed heavy metal unit, a decalcification unit, a centrifugal dehydration unit and an evaporation salt separation unit which are sequentially connected;
the low-temperature thermal degradation unit is used for removing dioxin and is provided with an incineration fly ash inlet and a fly ash outlet, and the fly ash outlet of the low-temperature thermal degradation unit is connected with the fly ash inlet of the washing dechlorination unit;
the water washing dechlorination unit is used for carrying out water washing dechlorination on the fly ash, the water washing dechlorination unit comprises an inlet for water and an outlet for ash, the water washing dechlorination unit is also provided with a water washing liquid outlet, and the water washing liquid outlet of the water washing dechlorination unit is connected with the inlet of the carbonation heavy metal fixing unit;
the carbonation fixing heavy metal unit is used for removing heavy metals from the washing liquid through carbonation treatment, an outlet of the carbonation fixing heavy metal unit is connected with an inlet of the decalcification unit, and the carbonation fixing heavy metal unit is also provided with a flue gas inlet;
the decalcification unit is used for decalcification of the rinsing liquid which is used for removing heavy metals in the previous device by carbonation treatment, an outlet of the decalcification unit is connected with an inlet of the centrifugal dehydration unit, and the decalcification unit is also provided with a medicament inlet;
the centrifugal dehydration unit is used for carrying out solid-liquid separation on the mixed liquid generated by the decalcification unit in the previous step, and also comprises a solid slag outlet, the solid separated by the centrifugal dehydration unit is discharged from the solid slag outlet, and the liquid outlet of the centrifugal dehydration unit is connected with the inlet of the evaporation salt separation unit;
the evaporation salt separation unit also comprises a salt outlet, and the evaporation salt separation unit carries out evaporation crystallization on the permeate liquid entering from the last step to separate salt, so as to obtain sodium chloride and potassium chloride.
2. The method for removing heavy metals from fly ash washing liquid coupling flue gas purification of a waste incineration plant according to claim 1, characterized by comprising the following steps:
s1: removing dioxin from the fly ash in a low-temperature thermal degradation unit;
s2: the fly ash is subjected to water washing dechlorination, the fly ash treated by the low-temperature thermal degradation unit enters a water washing dechlorination unit, water is added into the water washing dechlorination unit, chloride ions, heavy metal ions, calcium and magnesium ions and the like in the fly ash are dissolved into an aqueous solution, and the treated fly ash is discharged from an ash residue outlet;
s3: carrying out carbonation treatment on the water washing liquid to remove heavy metals, introducing the water washing liquid in the previous step into a carbonation fixed heavy metal unit, introducing flue gas containing carbon dioxide into the carbonation fixed heavy metal unit, and carrying out complex chemical reaction on the carbon dioxide and substances in the water washing liquid to generate stable heavy metal compounds;
s4: deeply decalcifying magnesium by softening with medicinal agent, adding Na into decalcifying unit 2 CO 3 、Na 2 SO 4 The calcium and magnesium ions are thoroughly removed by chemical agents;
s5: performing centrifugal dehydration for solid-liquid separation, allowing the mixed liquid from the decalcification unit to enter a centrifugal dehydration unit for solid-liquid separation, and directly discharging the separated solid slag;
s6: and (3) evaporating, crystallizing and separating salt, wherein an evaporation and salt separation unit is used for evaporating and crystallizing the permeate from the centrifugal dehydration unit so as to obtain sodium chloride and potassium chloride.
3. The method for removing heavy metals from fly ash washing liquid coupled with flue gas purification of a waste incineration plant according to claim 2, characterized by comprising the following steps: in the step S1, the thermal degradation temperature is 350-450 ℃, and the thermal degradation time is 60-120 minutes.
4. The method for removing heavy metals from fly ash washing liquid coupling flue gas purification of a waste incineration plant according to claim 2, characterized by comprising the following steps: in step S2, the mass ratio of the fly ash to the water is 1:1 to 1:5, the water washing time is 15-60 min, the stirring frequency is 60-300 r/min, and the water content of the ash residue after centrifugal dehydration is 40-50%.
5. The method for removing heavy metals from fly ash washing liquid coupled with flue gas purification of a waste incineration plant according to claim 2, characterized by comprising the following steps: in step S3, in the carbonation fixed heavy metal unit, the proportion of the original fly ash to the flue gas is 1:250 to 1:1250,1t of the original fly ash corresponds to 250-1250 Nm 3 The duration of carbonation treatment is controlled between 0.2 and 1 hour for the smoke per hour.
6. The method for removing heavy metals from fly ash washing liquid coupled with flue gas purification of a waste incineration plant according to claim 5, characterized by comprising the following steps: the smoke component comprises CO 2 、SO 2 NOx, HCl, wherein CO 2 8-12% of SO 2 The content is 0.1-80 mg/m 3 The content of NOx is 0.1-250 mg/m 3 The HCl content is 0.1-50 mg/m 3 。
7. The method for removing heavy metals from fly ash washing liquid coupled with flue gas purification of a waste incineration plant according to claim 2, characterized by comprising the following steps: in step S4, na 2 CO 3 、Na 2 SO 4 The adding amount is 7-12% of the original fly ash.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116474504A (en) * | 2023-05-26 | 2023-07-25 | 重庆三峰环境集团股份有限公司 | Flue gas treatment method and system for reducing and recycling waste incineration fly ash |
| CN118455238A (en) * | 2024-07-15 | 2024-08-09 | 光大环保技术装备（常州）有限公司 | Full-resource treatment method and treatment system for household garbage incineration fly ash |
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| JP2005279370A (en) * | 2004-03-29 | 2005-10-13 | Ebara Corp | Method and apparatus for washing incinerated ash and cement kiln dust with water |
| CN113145608A (en) * | 2021-03-12 | 2021-07-23 | 广州维港环保科技有限公司 | System and process for treating incineration fly ash through thermal desorption and carbon neutralization |
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| JP2005279370A (en) * | 2004-03-29 | 2005-10-13 | Ebara Corp | Method and apparatus for washing incinerated ash and cement kiln dust with water |
| CN113145608A (en) * | 2021-03-12 | 2021-07-23 | 广州维港环保科技有限公司 | System and process for treating incineration fly ash through thermal desorption and carbon neutralization |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116474504A (en) * | 2023-05-26 | 2023-07-25 | 重庆三峰环境集团股份有限公司 | Flue gas treatment method and system for reducing and recycling waste incineration fly ash |
| CN116474504B (en) * | 2023-05-26 | 2024-02-13 | 重庆三峰环境集团股份有限公司 | Flue gas treatment method and system for reducing and recycling waste incineration fly ash |
| CN118455238A (en) * | 2024-07-15 | 2024-08-09 | 光大环保技术装备（常州）有限公司 | Full-resource treatment method and treatment system for household garbage incineration fly ash |
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