CN114702045A - High-quality salt separation system and method for fly ash washing liquid - Google Patents
High-quality salt separation system and method for fly ash washing liquid Download PDFInfo
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- CN114702045A CN114702045A CN202210405769.6A CN202210405769A CN114702045A CN 114702045 A CN114702045 A CN 114702045A CN 202210405769 A CN202210405769 A CN 202210405769A CN 114702045 A CN114702045 A CN 114702045A
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- 150000003839 salts Chemical class 0.000 title claims abstract description 100
- 238000005406 washing Methods 0.000 title claims abstract description 74
- 238000000926 separation method Methods 0.000 title claims abstract description 64
- 239000007788 liquid Substances 0.000 title claims abstract description 54
- 239000010881 fly ash Substances 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 25
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 148
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 114
- 239000012452 mother liquor Substances 0.000 claims abstract description 108
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims abstract description 78
- 239000011591 potassium Substances 0.000 claims abstract description 78
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 78
- 239000011780 sodium chloride Substances 0.000 claims abstract description 73
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 66
- 239000000463 material Substances 0.000 claims abstract description 64
- 239000001103 potassium chloride Substances 0.000 claims abstract description 61
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 61
- 238000001704 evaporation Methods 0.000 claims abstract description 46
- 239000002002 slurry Substances 0.000 claims abstract description 46
- 230000008020 evaporation Effects 0.000 claims abstract description 43
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims abstract description 40
- 238000012545 processing Methods 0.000 claims abstract description 33
- 238000002425 crystallisation Methods 0.000 claims abstract description 15
- 230000008025 crystallization Effects 0.000 claims abstract description 15
- 230000001105 regulatory effect Effects 0.000 claims abstract description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 239000007787 solid Substances 0.000 claims description 21
- 238000001914 filtration Methods 0.000 claims description 20
- 238000005119 centrifugation Methods 0.000 claims description 17
- 239000011552 falling film Substances 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 12
- 239000013078 crystal Substances 0.000 claims description 12
- 238000004806 packaging method and process Methods 0.000 claims description 12
- 238000010992 reflux Methods 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000012544 monitoring process Methods 0.000 claims description 7
- 238000000746 purification Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 5
- 230000001276 controlling effect Effects 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 claims description 3
- -1 sodium chloride forms sodium salt Chemical class 0.000 claims description 3
- 238000005201 scrubbing Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 11
- 239000000047 product Substances 0.000 description 10
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 229910052708 sodium Inorganic materials 0.000 description 4
- 239000002562 thickening agent Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- BUKHSQBUKZIMLB-UHFFFAOYSA-L potassium;sodium;dichloride Chemical compound [Na+].[Cl-].[Cl-].[K+] BUKHSQBUKZIMLB-UHFFFAOYSA-L 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000013517 stratification Methods 0.000 description 2
- 238000004017 vitrification Methods 0.000 description 2
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000003039 volatile agent Substances 0.000 description 1
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- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- 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
- C01D3/14—Purification
-
- 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
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The application discloses a high-quality salt separation system and method for fly ash washing liquid, which comprises a feeding treatment module, a salt separation module, a sodium salt treatment module and a potassium salt treatment module; the salt separating module comprises a forced circulation crystallizer, a sodium salt discharge hole is formed in the bottom of the forced circulation crystallizer, a mother liquor overflow hole is formed in the side wall of the forced circulation crystallizer, the salt separating module is suitable for separating materials into sodium salt slurry and potassium-containing mother liquor, and the sodium salt slurry and the potassium-containing mother liquor are respectively conveyed to the sodium salt processing module and the potassium salt processing module; the potassium salt treatment module comprises a continuous regulator and a continuous crystallizer which are sequentially connected, the continuous regulator is suitable for automatically regulating the temperature and the pressure according to the concentration of the potassium-containing mother liquor, the continuous crystallizer is suitable for carrying out flash evaporation crystallization on the potassium-containing mother liquor so as to separate out potassium chloride, and the salt separation system can realize continuous and stable production of sodium chloride with the dry-basis purity of more than 99.1% and potassium chloride with the dry-basis purity of more than 98%.
Description
Technical Field
The application relates to the technical field of environmental protection, in particular to a high-quality salt separation system and method for fly ash washing liquid.
Background
The urban mineral products of fly ash contain a large amount of water-soluble sodium salt, potassium salt and calcium salt, and although the fly ash does not have toxicity, the existence of the water-soluble salt can cause great harm to the harmless and resource treatment of the fly ash. After harmless landfill treatment, water-soluble salt in the solidified body can be slowly leached, on one hand, the solidified body is collapsed, and heavy metals can also be leached; on the other hand, soluble salt enters the leachate, so that the difficulty of treating the leachate is increased, and the obtained miscellaneous salt does not go out. In the high-temperature curing process, although the fly ash can be used as a building material after vitrification, the water-soluble salt is used as a chlorinated volatile agent, so that the curing of heavy metals is seriously influenced, and equipment and refractory materials are seriously corroded in the high-temperature vitrification process.
Therefore, before the fly ash is harmless and recycled, water-soluble salt in the fly ash must be separated, the content of sodium chloride and potassium chloride in the fly ash is high after passing through a water washing system and a water treatment system, the simple membrane treatment cost is high, and the system is unstable, so that the MVR evaporation device is a process adopted by most of enterprises at present, but most of enterprises in the industry at present directly evaporate miscellaneous salt and treat the miscellaneous salt as solid waste, the recycling can not be realized, and the treatment cost is high. Some enterprises adopt evaporative crystallization and cooling crystallization processes, but because the cooling crystallization adopts an intermittent process, the product quality cannot be ensured, and in order to fundamentally solve the environmental problem, more and more enterprises use a treatment liquid salt separation system after washing the fly ash.
However, the existing fly ash washing salt separation system has the following defects: the purity of the sodium chloride salt and the potassium chloride salt obtained by washing water with salt is low (the sodium chloride is 85-92 percent, and the potassium chloride is 50-85 percent) at present, and the stable operation and output are difficult; the obtained byproduct salt product has low quality and is difficult to utilize, thereby causing overstock phenomenon.
Disclosure of Invention
One objective of the present application is to provide a high-quality salt separation system and method for fly ash water washing liquid capable of continuously and stably producing sodium chloride with a dry-basis purity of 99.1% or more and potassium chloride with a dry-basis purity of 98% or more.
In order to achieve the above purposes, the technical scheme adopted by the application is as follows: a high-quality salt separation system for fly ash water washing liquid comprises a feeding treatment module, a salt separation module, a sodium salt treatment module and a potassium salt treatment module;
the feeding processing module is connected with the salt separating module and is suitable for preheating and pre-concentrating materials and conveying the processed materials to the salt separating module;
the salt separating module comprises a forced circulation crystallizer, a sodium salt discharge port is formed in the bottom of the forced circulation crystallizer, the sodium salt discharge port is connected with the sodium salt processing module, a mother liquor overflow port is formed in the side wall of the forced circulation crystallizer, the mother liquor overflow port is connected with the potassium salt processing module, the salt separating module is suitable for separating materials into sodium salt slurry and potassium-containing mother liquor, and the sodium salt slurry and the potassium-containing mother liquor are respectively conveyed to the sodium salt processing module and the potassium salt processing module;
the sodium salt processing module is suitable for separating out sodium chloride in the sodium salt slurry, and processing and packaging the sodium chloride;
the potassium salt treatment module comprises a continuous regulator and a continuous crystallizer which are sequentially connected, the continuous regulator is connected with the forced circulation crystallizer, the continuous regulator is suitable for automatically regulating the temperature and the pressure according to the concentration of the potassium-containing mother liquor, and the continuous crystallizer is suitable for carrying out flash evaporation crystallization on the potassium-containing mother liquor so as to separate out potassium chloride.
As an improvement, the feeding processing module comprises a feeding unit, a preheating unit and a concentration unit which are connected in sequence, the feeding unit is suitable for storing and conveying materials, a first preheater, a second preheater and a third preheater are arranged in the preheating unit, the preheating unit is suitable for carrying out three-level preheating on the materials, a first evaporation cavity and a second evaporation cavity are arranged in the concentration unit, the first evaporation cavity is suitable for concentrating the original materials to a low-concentration state, and the second evaporation cavity is suitable for further concentrating the low-concentration materials to a high-concentration state.
Preferably, the feed unit comprises an MVR feed buffer tank, the first preheater comprises a condensed water preheater, the second preheater comprises a non-condensing steam preheater, the third preheater comprises a steam preheater, and the concentration unit comprises a falling film evaporator.
The sodium salt treatment module comprises a first centrifugal unit, a first salt washing unit and a second centrifugal unit which are sequentially connected, the first centrifugal unit is connected with the forced circulation crystallizer, the first centrifugal unit is suitable for carrying out primary centrifugal separation on sodium salt slurry separated by the forced circulation crystallizer, the first salt washing unit is suitable for washing and purifying sodium chloride separated out by the primary centrifugal separation, and the second centrifugal unit is suitable for carrying out secondary centrifugal separation on the sodium salt slurry formed by washing to obtain solid sodium chloride; a first reflux device is connected between the forced circulation crystallizer and the first centrifugal unit and between the forced circulation crystallizer and the second centrifugal unit, and the first reflux device is suitable for returning the mother liquor centrifuged by the first centrifugal unit and the second centrifugal unit to the forced circulation crystallizer.
The potassium salt treatment module further comprises a third centrifugal unit, a second salt washing unit and a fourth centrifugal unit which are sequentially connected, wherein the third centrifugal unit is connected with the continuous crystallizer, the third centrifugal unit is suitable for carrying out primary centrifugal separation on potassium chloride separated by the continuous crystallizer, the second salt washing unit is suitable for washing and purifying potassium chloride separated out by the primary centrifugal separation, and the fourth centrifugal unit is suitable for carrying out secondary centrifugal separation on potassium-containing mother liquor formed by washing to obtain solid potassium chloride; and a second reflux device is connected between the forced circulation crystallizer and the third centrifugal unit and between the forced circulation crystallizer and the fourth centrifugal unit, and the second reflux device is suitable for returning the mother liquor centrifuged by the third centrifugal unit and the fourth centrifugal unit to the forced circulation crystallizer.
As a refinement, the potassium salt processing module further comprises a centrifugal filtering device, the centrifugal filtering device is connected with the salt separating module and the continuous regulator, the centrifugal filtering device is suitable for carrying out centrifugal filtration on potassium-containing mother liquor, and the centrifugal filtering device is suitable for returning centrifuged sodium chloride to the salt separating module.
A high-quality salt separation method for fly ash water washing liquid comprises the following steps:
s100, preheating feeding materials, namely heating the materials after washing the fly ash by virtue of condensate water preheating, non-condensable gas preheating and non-condensable gas preheating in sequence;
s200, evaporation and concentration are carried out, and 11% of low-concentration material and 18.9% of high-concentration material can be obtained after the preheated material passes through a falling film evaporator;
s300, evaporation and separation are carried out, the concentrated material enters a forced circulation crystallizer for evaporation, the precipitated sodium chloride forms sodium salt slurry with a solid-to-liquid ratio of 30%, the sodium salt slurry is conveyed to a sodium salt treatment module from a sodium salt discharge port, and potassium-containing mother liquor overflows to a potassium salt treatment module from a mother liquor overflow port;
s400, crystallizing sodium chloride, enabling sodium salt slurry to flow into a first centrifugal unit for centrifugation to obtain sodium chloride crystal salt, enabling the sodium chloride crystal salt to enter a first salt washing unit for washing and purification, enabling the washed sodium salt slurry to enter a second centrifugal unit for centrifugation to obtain solid sodium chloride, and enabling mother liquor obtained by the centrifugation of the first centrifugal unit and the second centrifugal unit to return to a forced circulation crystallizer for continuous concentration;
s500, adjusting potassium-containing mother liquor, overflowing the potassium-containing mother liquor to a potassium salt feeding tank, and pumping the potassium salt-containing mother liquor into a continuous adjuster by a potassium salt feeding pump, wherein the continuous adjuster automatically adjusts the temperature and the pressure according to the concentration of the potassium-containing mother liquor at the front end;
s600, crystallizing potassium chloride, conveying the adjusted potassium-containing mother liquor to a continuous crystallizer by utilizing differential pressure overflow for flash evaporation crystallization to obtain sylvite slurry, conveying the sylvite slurry to a third centrifugal unit for centrifugation, conveying the centrifuged potassium chloride to a second salt washing unit for washing and purification, conveying the washed sylvite slurry to a fourth centrifugal unit for centrifugation to obtain solid sodium chloride, and returning the centrifuged mother liquor of the third centrifugal unit and the fourth centrifugal unit to the forced circulation crystallizer for continuous concentration;
s700, packaging, namely packaging the obtained solid sodium chloride and solid potassium chloride.
According to an embodiment of the present invention, the step S500 includes the steps of:
s510, carrying out online monitoring, arranging flowmeters on overflow pipelines of a feeding unit and a forced circulation crystallizer, calculating a theoretical overfeeding value, and accurately controlling the concentration of potassium chloride in potassium-containing mother liquor entering a continuous regulator;
s520, performing off-line detection, namely sampling the material in the forced circulation crystallizer to detect the potassium content of the material;
s530, removing sodium chloride, centrifuging the excessive sodium chloride in the potassium-containing mother liquor by using a centrifugal filtering device, and returning the precipitated sodium chloride to the forced circulation crystallizer for continuous evaporation.
According to an embodiment of the present invention, in the on-line monitoring of the step S510, the potassium chloride concentration in the potassium-containing mother liquor entering the continuous regulator is controlled to be 15% to 22%.
According to an embodiment of the present invention, the step S600 includes the steps of:
s610, mixing and cooling, and mixing the adjusted potassium-containing mother liquor with the potassium-containing mother liquor circulating in the continuous crystallizer to reduce the superheat degree.
Compared with the prior art, the beneficial effect of this application lies in:
1. the forced circulation crystallizer in the partial salt module is structurally optimized, so that sodium chloride is crystallized out of the forced circulation crystallizer, further crystallization in the effect body is increased, meanwhile, the forced circulation crystallizer can overflow qualified potassium-containing mother liquor out of the system by utilizing the height difference of the internal structure, sodium chloride is crystallized out, and meanwhile, the qualified potassium-containing mother liquor with stable components is prepared, favorable conditions can be provided for subsequent potassium chloride separation and thermal sodium chloride separation, and efficient primary salt separation operation on materials is realized.
2. A continuous regulator is additionally arranged to carry out depth regulation on the qualified potassium-containing mother liquor overflowing from the forced circulation crystallizer, the temperature and pressure can be automatically regulated according to the concentration of the qualified potassium-containing mother liquor at the front end, and entrainment of excessive sodium salt crystals precipitated in a liquid phase due to temperature reduction is reduced; the continuous regulator is also provided with a high-precision centrifugal filtering device, can centrifuge out redundant sodium chloride and deeply remove the redundant sodium chloride, and returns the sodium chloride to the forced circulation crystallizer at the front end to continuously evaporate sodium salt, so that the cyclic utilization rate of materials is increased, and the product purity is improved.
3. A continuous flash-evaporation crystallizer is used for carrying out flash evaporation cooling on qualified mother liquor which is adjusted and sent out by a continuous regulator, and the potassium chloride precipitation as a main part of the system can be calculated through a sodium chloride-potassium chloride ternary system phase diagram, so that the continuous and stable crystallization of potassium chloride is realized, and the labor intensity and the product instability are greatly reduced.
Drawings
FIG. 1 is a flow diagram of a salt stratification system according to a preferred embodiment of the present application;
FIG. 2 is a structural view of a forced circulation crystallizer according to a preferred embodiment of the present application;
FIG. 3 is a flow diagram of a prior art salt stratification system according to the present application.
In the figure: 1. a forced circulation crystallizer; 11. a circulating feed inlet; 12. a sodium salt discharge port; 13. a mother liquor overflow port; 14. a separator.
Detailed Description
The present application is further described below with reference to specific embodiments, and it should be noted that, without conflict, any combination between the embodiments or technical features described below may form a new embodiment.
In the description of the present application, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be construed as limiting the specific scope of protection of the present application.
It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The terms "comprises," "comprising," and "having," and any variations thereof, in the description and claims of this application, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The present application is further described with reference to the accompanying drawings:
as shown in FIG. 3, the flow of the water washing and salt separating system of the fly ash in the prior art is as follows: the treated liquid after washing the fly ash firstly enters the falling film evaporator through a feed pump (a feed system), a preheating system, an electromagnetic flow meter and an automatic regulating valve, the material forms feed liquid in the falling film heater, the feed liquid is uniformly distributed on the inner wall of a tube array through a distributor at the top of the heater, the feed liquid flows downwards in a film shape, the feed liquid continuously exchanges heat with heating steam of a shell pass of the heater and evaporates in the flowing process, the feed liquid enters a primary separation cavity at the bottom of the heater and then is subjected to flash evaporation for primary gas-liquid separation, most of the feed liquid is discharged, a small amount of the feed liquid and all secondary steam generated by the feed liquid enter a separator, the feed liquid and the secondary steam are subjected to secondary gas-liquid separation in the separator, the separated feed liquid is mixed with most of the feed liquid discharged by a discharge pipe at the bottom of the separator and then enters a forced circulation evaporation system, or is pumped back to the top of the heater through a forced falling film pump, and continuing heating and evaporating.
The material is continuously heated in the forced circulation heater, the material liquid flows at a high speed from bottom to top in the heat exchange tube under the action of the circulating pump, the scaling of the tube wall is reduced, the material liquid and the heating steam of the shell pass of the heater continuously exchange heat and evaporate in the flowing process, and the material liquid enters the separator. The material liquid and the secondary steam are flashed in the separator to carry out gas-liquid separation, the separated material liquid passes through a forced circulation pump, is continuously heated and evaporated in a forced circulation effect, and then reaches a set concentration, and is conveyed to the thickener through a discharge pump.
The crystal slurry liquid is stored in the thickener for enough time to eliminate supersaturation and finish clarification, the thickened material is subjected to solid-liquid separation by a centrifugal machine to separate out solid sodium chloride salt, part of the mother liquid is sent back to the forced circulation effect body, forced circulation heating, evaporation and concentration are continuously carried out, part of the mother liquid is sent to an intermittent cooling tank, the feed liquid is cooled under the action of circulating cooling water of a jacket of the intermittent cooling tank, potassium chloride is separated out, and finally, the potassium chloride is separated out through thickening and solid-liquid separation by the centrifugal machine.
The above system has the following disadvantages:
1. when the project is stable in operation, the purity of sodium chloride and potassium chloride obtained by evaporating and separating salt only reaches 85-92% of sodium chloride and 50-85% of potassium chloride; the quality of the resource products is poor, and the downstream utilization cannot be introduced, so that the accumulation of salt is caused.
2. The control of the evaporation end point is coarse and maniac, the concentration of the qualified potassium-containing mother liquor cannot be controlled well, and the phenomenon represented by overhigh or overlow concentration is the fluctuation of the purity of the sodium chloride and the potassium chloride.
3. The problem of sodium chloride entrainment in the potassium mother liquor removed from the cooling section cannot be eliminated, resulting in low potassium salt purity.
4. Due to seasonal fluctuation of the composition of the fly ash, the composition of the fly ash after washing liquid is greatly changed, and the purity of the sodium chloride and potassium chloride salt is further reduced after the water quality fluctuates.
5. Sodium chloride is entrained in the sodium separation mother liquor, and a method of adding stock solution or condensed water to dilute and dissolve sodium chloride is adopted, so that the purity of potassium chloride is improved, the solid-to-liquid ratio of separated potassium chloride is reduced, and the energy consumption of system operation is increased.
6. The solid-liquid ratio of the sylvite feeding mother liquor is reduced, a continuous double-push centrifuge is adopted to centrifuge materials, the feeding cannot leave the thickener, the materials in the thickener are layered, and the phenomenon that the centrifuge is easy to cause insufficient feeding concentration and produce dilution is easily caused.
7. Because the intermittent reaction kettle is adopted for cooling, the operation intensity of people is greatly increased, and the fluctuation of each tank or each batch of products is very high, so that the product purity is suddenly high and suddenly low, and the quality is unstable.
As shown in fig. 1 to 2, a preferred embodiment of the present application includes a feed treatment module, a salt separation module, a sodium salt treatment module, and a potassium salt treatment module;
the feeding processing module is connected with the salt separating module, the feeding processing module is suitable for preheating and pre-concentrating materials, the materials after being processed are conveyed to the salt separating module, the feeding processing module comprises a feeding unit, a preheating unit and a concentrating unit, the feeding unit comprises a pump valve group and a flowmeter, the feeding unit is suitable for storing and conveying the materials, a first preheater, a second preheater and a third preheater are arranged in the preheating unit, the preheating unit is suitable for carrying out three-level preheating on the materials, a first evaporation cavity and a second evaporation cavity are arranged in the concentrating unit, the first evaporation cavity is suitable for concentrating the original materials to be in a low-concentration state, and the second evaporation cavity is suitable for further concentrating the low-concentration materials to be in a high-concentration state.
The feed unit preferably uses an MVR feed buffer tank, the first preheater preferably uses a condensed water preheater, the second preheater preferably uses a non-condensed water preheater, the third preheater preferably uses a steam preheater, and the concentration unit preferably uses a falling film evaporator.
The material directly loops through comdenstion water pre-heater, noncondensation preheater and steam pre-heater, ensures that the material boiling point feeds into falling film evaporator, improves the heat exchange efficiency that the material advances the falling film, and the material can further be concentrated in falling film evaporator, and the two segmentation structures of falling film evaporator can realize the regular automatic switch-over in first evaporation chamber and second evaporation chamber, increase the operation cycle of equipment, still be provided with mass flow meter in the falling film evaporator, and mass flow meter is used for surveying the survey mass flow meterDetermining the discharge density of the falling film evaporator, and controlling the discharge density to be 1100-1180 kg/m3The overall harmony of the system can be conveniently detected, and the pre-concentrated material is conveyed to the preposed circulating crystallizer through the excess pump.
The salt separating module comprises a forced circulation crystallizer 1, a sodium salt discharge port 12 is formed in the bottom of the forced circulation crystallizer 1, the sodium salt discharge port 12 is connected with a sodium salt treatment module, a mother liquor overflow port 13 is formed in the side wall of the forced circulation crystallizer 1, the mother liquor overflow port 13 is connected with a potassium salt treatment module, the salt separating module is suitable for separating materials into sodium salt slurry and potassium-containing mother liquor, and the sodium salt slurry and the potassium-containing mother liquor are respectively conveyed to the sodium salt treatment module and the potassium salt treatment module;
the salt separation process of the sodium salt slurry and the potassium-containing mother liquor is respectively as follows: the slurry reaching a certain concentration is subjected to double detection through a double-flange densimeter and a mass flowmeter, the solid-liquid ratio of the discharged concentration is accurately controlled to be kept at 30%, and the slurry reaching the qualified concentration is fed to a sodium salt processing module through a discharging pump; the potassium-containing mother liquor is overflowed by the forced circulation crystallizer 1 through the height difference between the circulation feed inlet 11 and the mother liquor overflow port 13, the partition plate 14 is arranged between the circulation feed inlet 11 and the mother liquor overflow port 13, an overflow area is formed between the partition plate 14 and the side wall of the forced circulation crystallizer, so that clear liquid overflows from the mother liquor overflow port 13 as far as possible, the outflow of sodium salt slurry is reduced, and the qualified potassium-containing mother liquor of the forced circulation crystallizer 1 is discharged into a storage tank in a cache of a potassium salt processing module through a potassium salt overflow pipeline connected with the mother liquor overflow port 13 to be stored for subsequent processing.
The forced circulation crystallizer 1 in the partial salt module is structurally optimized, so that sodium chloride is crystallized out of the forced circulation crystallizer 1, the crystallization is further increased in the effect body, meanwhile, the forced circulation crystallizer 1 can overflow qualified potassium-containing mother liquor out of the system by utilizing the height difference of the internal structure, the sodium chloride is crystallized out, meanwhile, the qualified potassium-containing mother liquor with stable components is prepared, favorable conditions can be provided for subsequent potassium chloride separation and thermal sodium chloride separation, and the efficient primary salt separation operation of materials is realized.
The sodium salt processing module is suitable for separating out sodium chloride in sodium salt slurry, processing and packaging the sodium chloride, and comprises a first centrifugal unit, a first salt washing unit and a second centrifugal unit which are sequentially connected, wherein the first centrifugal unit is connected with the forced circulation crystallizer 1, the first centrifugal unit is suitable for carrying out primary centrifugal separation on the sodium salt slurry separated by the forced circulation crystallizer 1, the first salt washing unit is suitable for washing and purifying the sodium chloride separated by the primary centrifugal separation, and the second centrifugal unit is suitable for carrying out secondary centrifugal separation on the sodium salt slurry formed by washing to obtain solid sodium chloride; a first reflux device is connected between the forced circulation crystallizer 1 and the first centrifugal unit and between the forced circulation crystallizer 1 and the second centrifugal unit, and the first reflux device is suitable for returning the mother liquor centrifuged by the first centrifugal unit and the second centrifugal unit to the forced circulation crystallizer 1.
The method comprises the steps that a mother liquor obtained by centrifuging a sodium salt slurry in a first centrifugal unit returns to a forced circulation crystallizer 1 to be continuously concentrated, the obtained sodium chloride crystal salt enters a first salt washing unit, the first salt washing unit further washes the preliminarily obtained sodium chloride crystal salt to remove impurities, the quality of sodium chloride is improved, the slurry formed by washing enters a second centrifugal unit, part of the centrifuged mother liquor returns to an evaporation system, part of the centrifuged mother liquor continuously participates in salt washing, and solid sodium chloride enters a packaging system to be packaged.
The potassium salt processing module comprises a continuous regulator and a continuous crystallizer which are sequentially connected, the continuous regulator is connected with the forced circulation crystallizer 1, the continuous regulator is suitable for automatically regulating the temperature and the pressure according to the concentration of the potassium-containing mother liquor, and the continuous crystallizer is suitable for carrying out flash evaporation crystallization on the potassium-containing mother liquor so as to separate out potassium chloride.
The continuous regulator is additionally arranged to deeply regulate the qualified potassium-containing mother liquor overflowed from the forced circulation crystallizer 1, the temperature and the pressure can be automatically regulated according to the concentration of the qualified potassium-containing mother liquor at the front end, and the entrainment of excessive sodium salt crystals precipitated due to cooling in the liquid phase is reduced.
The continuous flash evaporation crystallizer is used for carrying out flash evaporation cooling on the qualified mother liquor which is regulated and sent out by the continuous regulator, and the sodium chloride-potassium chloride ternary system phase diagram can be used for deducing that the potassium chloride is mainly separated out, so that the continuous and stable crystallization of potassium chloride is realized, and the labor intensity and the product instability are greatly reduced.
The potassium salt treatment module also comprises a third centrifugal unit, a second salt washing unit and a fourth centrifugal unit which are sequentially connected, the third centrifugal unit is connected with the continuous crystallizer, the third centrifugal unit is suitable for carrying out primary centrifugal separation on potassium chloride separated by the continuous crystallizer, the second salt washing unit is suitable for washing and purifying potassium chloride separated out by the primary centrifugal separation, and the fourth centrifugal unit is suitable for carrying out secondary centrifugal separation on potassium-containing mother liquor formed by washing to obtain solid potassium chloride; and a second reflux device is connected between the forced circulation crystallizer 1 and the third centrifugal unit and between the forced circulation crystallizer 1 and the fourth centrifugal unit, and the second reflux device is suitable for returning the mother liquor centrifuged by the third centrifugal unit and the fourth centrifugal unit to the forced circulation crystallizer 1.
And potassium chloride separated out by the continuous regulator is sent into a third centrifugal unit, mother liquor obtained by centrifugation returns to the forced circulation crystallizer 1, potassium salt obtained by centrifugation enters a second salt washing unit, impurities are further removed, purification is carried out, slurry formed by washing enters the second centrifugal unit, part of the centrifuged mother liquor returns to an evaporation system, part of the centrifuged mother liquor continues to participate in salt washing, and solid potassium chloride enters a packaging system for packaging.
The potassium salt processing module further comprises a centrifugal filtering device, the centrifugal filtering device is connected with the salt separating module and the continuous regulator, the centrifugal filtering device is suitable for carrying out centrifugal filtering on potassium-containing mother liquor, the centrifugal filtering device is suitable for returning centrifuged sodium chloride to the salt separating module, redundant sodium chloride can be centrifuged and removed deeply, the sodium chloride is returned to the forced circulation crystallizer 1 at the front end to continue to evaporate sodium salt, the circulation utilization rate of materials is increased, and the product purity is improved.
The first backflow device and the second backflow device comprise a valve pump set and a backflow pipeline, the first centrifugal unit, the second centrifugal unit, the third centrifugal unit and the fourth centrifugal unit comprise centrifuges, and the first salt washing unit and the second salt washing unit comprise salt washing tanks, centrifuges and mother liquor tanks.
The system aims at the water inlet fluctuation characteristic of the fly ash, innovatively provides a process scheme route of continuous crystallization from the process, realizes high-purity separation of sodium chloride and potassium chloride, ensures that the dry-basis purity of the obtained sodium chloride can be 99.1 percent or more and the dry-basis purity of the potassium chloride can be 98 percent or more, can ensure the stable operation of the whole line under the fluctuation of water quality to a certain degree, recycles the condensed water evaporated by the system for the washing of the fly ash, uses the high-purity obtained sodium chloride as industrial salt for soda production, ion membrane caustic soda and the like, recycles the obtained potassium chloride as industrial potash fertilizer, supplements the gap of potassium resources in China, and truly realizes the recycling comprehensive recycling of wastes.
A high-quality salt separation method for fly ash water washing liquid comprises the following steps:
s100, preheating feeding materials, namely heating the materials after washing the fly ash by virtue of condensate water preheating, non-condensable gas preheating and non-condensable gas preheating in sequence;
s200, evaporation and concentration are carried out, and after the preheated material passes through a falling film evaporator, about 11% of low-concentration material and about 18.9% of high-concentration material can be obtained;
s300, evaporation and separation are carried out, the concentrated material enters a forced circulation crystallizer 1 for evaporation, the precipitated sodium chloride forms sodium salt slurry with a solid-to-liquid ratio of 30%, the sodium salt slurry is conveyed to a sodium salt treatment module from a sodium salt discharge port 12, and potassium-containing mother liquor overflows to a potassium salt treatment module from a mother liquor overflow port 13;
s400, crystallizing sodium chloride, enabling sodium salt slurry to flow into a first centrifugal unit for centrifugation to obtain sodium chloride crystal salt, enabling the sodium chloride crystal salt to enter a first salt washing unit for washing and purification, enabling the washed sodium salt slurry to enter a second centrifugal unit for centrifugation to obtain solid sodium chloride, and enabling mother liquor obtained by the centrifugation of the first centrifugal unit and the second centrifugal unit to return to a forced circulation crystallizer 1 for continuous concentration;
s500, adjusting potassium-containing mother liquor, overflowing the potassium-containing mother liquor to a potassium salt feeding tank, and pumping the potassium salt-containing mother liquor into a continuous adjuster by a potassium salt feeding pump, wherein the continuous adjuster automatically adjusts the temperature and the pressure according to the concentration of the potassium-containing mother liquor at the front end;
s600, crystallizing potassium chloride, overflowing and conveying the adjusted potassium-containing mother liquor to a continuous crystallizer by utilizing a pressure difference (the pressure in a continuous regulator is greater than the pressure in the continuous crystallizer) for flash evaporation crystallization to obtain sylvite slurry, feeding the sylvite slurry into a third centrifugal unit for centrifugation, feeding the centrifuged potassium chloride into a second salt washing unit for washing and purification, feeding the washed sylvite slurry into a fourth centrifugal unit for centrifugation to obtain solid sodium chloride, and feeding the centrifuged mother liquor of the third centrifugal unit and the fourth centrifugal unit back to the forced circulation crystallizer 1 for continuous concentration;
s700, packaging, namely packaging the obtained solid sodium chloride and solid potassium chloride.
The continuous regulator can automatically regulate the temperature and the pressure according to the content of sodium and the content of potassium in the concentration of the front-end qualified potassium-containing mother liquor, the temperature regulation range of the continuous regulator is 70-100 ℃, and the pressure regulation range is-70 kpa-0 kpa; when the sodium content is high and the potassium content is low, the temperature and the pressure in the continuous regulator are adjusted downwards, and when the sodium content is low and the potassium content is high, the temperature and the pressure in the continuous regulator are slightly adjusted downwards, so that the entrainment of excessive sodium salt in a liquid phase, which is separated out of crystals due to temperature reduction, can be reduced.
Wherein, step S500 includes the steps of:
s510, carrying out online monitoring, arranging flowmeters on overflow pipelines of a feeding unit and the forced circulation crystallizer 1, calculating a theoretical overfeeding value, and accurately controlling the concentration of potassium chloride in potassium-containing mother liquor entering a continuous regulator;
s520, performing off-line detection, namely sampling the material in the forced circulation crystallizer 1 to detect the potassium content;
s530, removing sodium chloride, centrifuging redundant sodium chloride in the potassium-containing mother liquor by using a centrifugal filtering device, and returning the precipitated sodium chloride to the forced circulation crystallizer 1 for continuous evaporation.
Wherein, in the on-line monitoring of step S510, the potassium chloride concentration in the potassium-containing mother liquor entering the continuous regulator is controlled to be 15% to 22%.
The potassium content in the welding mother liquor is accurately controlled in an online monitoring mode, so that high-purity potassium separation is facilitated, premature precipitation of potassium salt in a continuous regulator is avoided, and potassium salt is prevented from being carried when a subsequent centrifugal filtering device is used for separating sodium chloride; the purpose of offline detection of the potassium content is to control the potassium content of potassium-containing mother liquor through manual intervention when equipment monitored on line fails, so that the high-purity separation of sodium chloride and potassium chloride by a system is guaranteed.
Wherein, step S600 includes the steps of:
and S610, mixing and cooling, mixing the adjusted potassium-containing mother liquor with the potassium-containing mother liquor circulating in the continuous crystallizer to reduce the superheat degree, wherein the reduced superheat degree is preferably kept at about 50 ℃.
The foregoing has described the general principles, essential features, and advantages of the application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, which are merely illustrative of the principles of the application, but that various changes and modifications may be made without departing from the spirit and scope of the application, and such changes and modifications are intended to be within the scope of the application as claimed. The scope of protection claimed by this application is defined by the following claims and their equivalents.
Claims (10)
1. A fly ash washing liquid high-quality salt separation system is characterized in that: the device comprises a feeding processing module, a salt separating module, a sodium salt processing module and a potassium salt processing module;
the feeding processing module is connected with the salt separation module and is suitable for preheating and pre-concentrating materials and conveying the processed materials to the salt separation module;
the salt separating module comprises a forced circulation crystallizer, a sodium salt discharge port is formed in the bottom of the forced circulation crystallizer, the sodium salt discharge port is connected with the sodium salt processing module, a mother liquor overflow port is formed in the side wall of the forced circulation crystallizer, the mother liquor overflow port is connected with the potassium salt processing module, the salt separating module is suitable for separating materials into sodium salt slurry and potassium-containing mother liquor, and the sodium salt slurry and the potassium-containing mother liquor are respectively conveyed to the sodium salt processing module and the potassium salt processing module;
the sodium salt processing module is suitable for separating out sodium chloride in the sodium salt slurry, and processing and packaging the sodium chloride;
the potassium salt treatment module comprises a continuous regulator and a continuous crystallizer which are sequentially connected, the continuous regulator is connected with the forced circulation crystallizer, the continuous regulator is suitable for automatically regulating the temperature and the pressure according to the concentration of the potassium-containing mother liquor, and the continuous crystallizer is suitable for carrying out flash evaporation crystallization on the potassium-containing mother liquor so as to separate out potassium chloride.
2. The high-quality salt separation system for the fly ash water washing liquid as claimed in claim 1, wherein: the feeding processing module comprises a feeding unit, a preheating unit and a concentration unit which are connected in sequence, the feeding unit is suitable for storing and conveying materials, a first preheater, a second preheater and a third preheater are arranged in the preheating unit, the preheating unit is suitable for carrying out three-level preheating on the materials, a first evaporation cavity and a second evaporation cavity are arranged in the concentration unit, the first evaporation cavity is suitable for concentrating the original materials to a low-concentration state, and the second evaporation cavity is suitable for further concentrating the low-concentration materials to a high-concentration state.
3. The high-quality salt separation method for the fly ash water washing liquid as claimed in claim 2, wherein the method comprises the following steps: the feed unit includes MVR feeding buffer memory pond, first preheater includes the comdenstion water pre-heater, the second pre-heater includes not condensing the steam pre-heater, the third pre-heater includes steam pre-heater, the concentration unit includes falling film evaporator.
4. The high-quality salt separation method for the fly ash water washing liquid as claimed in claim 1, wherein the method comprises the following steps: the sodium salt treatment module comprises a first centrifugal unit, a first salt washing unit and a second centrifugal unit which are sequentially connected, the first centrifugal unit is connected with the forced circulation crystallizer, the first centrifugal unit is suitable for carrying out primary centrifugal separation on sodium salt slurry separated by the forced circulation crystallizer, the first salt washing unit is suitable for washing and purifying sodium chloride separated out by the primary centrifugal separation, and the second centrifugal unit is suitable for carrying out secondary centrifugal separation on the sodium salt slurry formed by washing to obtain solid sodium chloride; a first reflux device is connected between the forced circulation crystallizer and the first centrifugal unit and between the forced circulation crystallizer and the second centrifugal unit, and the first reflux device is suitable for returning the mother liquor centrifuged by the first centrifugal unit and the second centrifugal unit to the forced circulation crystallizer.
5. The high-quality salt separation method for the fly ash water washing liquid as claimed in claim 1, wherein the method comprises the following steps: the potassium salt treatment module further comprises a third centrifugal unit, a second salt washing unit and a fourth centrifugal unit which are sequentially connected, the third centrifugal unit is connected with the continuous crystallizer, the third centrifugal unit is suitable for carrying out primary centrifugal separation on potassium chloride separated by the continuous crystallizer, the second salt washing unit is suitable for washing and purifying potassium chloride separated out by the primary centrifugal separation, and the fourth centrifugal unit is suitable for carrying out secondary centrifugal separation on potassium-containing mother liquor formed by washing to obtain solid potassium chloride; and a second reflux device is connected between the forced circulation crystallizer and the third centrifugal unit and between the forced circulation crystallizer and the fourth centrifugal unit, and the second reflux device is suitable for returning the mother liquor centrifuged by the third centrifugal unit and the fourth centrifugal unit to the forced circulation crystallizer.
6. The high-quality salt separation method for the fly ash water washing liquid as claimed in claim 1, wherein the method comprises the following steps: the potassium salt processing module further comprises a centrifugal filtering device, the centrifugal filtering device is connected with the salt separating module and the continuous regulator, the centrifugal filtering device is suitable for carrying out centrifugal filtering on potassium-containing mother liquor, and the centrifugal filtering device is suitable for returning centrifuged sodium chloride to the salt separating module.
7. A high-quality salt separation method for fly ash water washing liquid is characterized by comprising the following steps:
s100, preheating feeding materials, namely heating the materials after washing the fly ash by virtue of condensate water preheating, non-condensable gas preheating and non-condensable gas preheating in sequence;
s200, evaporation and concentration are carried out, and 11% of low-concentration material and 18.9% of high-concentration material can be obtained after the preheated material passes through a falling film evaporator;
s300, evaporation and separation are carried out, the concentrated material enters a forced circulation crystallizer for evaporation, the precipitated sodium chloride forms sodium salt slurry with a solid-to-liquid ratio of 30%, the sodium salt slurry is conveyed to a sodium salt treatment module from a sodium salt discharge port, and potassium-containing mother liquor overflows to a potassium salt treatment module from a mother liquor overflow port;
s400, crystallizing sodium chloride, enabling sodium salt slurry to flow into a first centrifugal unit for centrifugation to obtain sodium chloride crystal salt, enabling the sodium chloride crystal salt to enter a first salt washing unit for washing and purification, enabling the washed sodium salt slurry to enter a second centrifugal unit for centrifugation to obtain solid sodium chloride, and enabling mother liquor obtained by the centrifugation of the first centrifugal unit and the second centrifugal unit to return to a forced circulation crystallizer for continuous concentration;
s500, adjusting potassium-containing mother liquor, overflowing the potassium-containing mother liquor to a potassium salt feeding tank, and pumping the potassium salt-containing mother liquor into a continuous adjuster by a potassium salt feeding pump, wherein the continuous adjuster automatically adjusts the temperature and the pressure according to the concentration of the potassium-containing mother liquor at the front end;
s600, crystallizing potassium chloride, conveying the adjusted potassium-containing mother liquor to a continuous crystallizer by utilizing differential pressure overflow for flash evaporation crystallization to obtain sylvite slurry, conveying the sylvite slurry to a third centrifugal unit for centrifugation, conveying the centrifuged potassium chloride to a second salt washing unit for washing and purification, conveying the washed sylvite slurry to a fourth centrifugal unit for centrifugation to obtain solid sodium chloride, and returning the centrifuged mother liquor of the third centrifugal unit and the fourth centrifugal unit to the forced circulation crystallizer for continuous concentration;
s700, packaging, namely packaging the obtained solid sodium chloride and solid potassium chloride.
8. The high-quality salt separation method for the fly ash water washing liquid according to claim 7, wherein the step S500 comprises the steps of:
s510, carrying out online monitoring, arranging flowmeters on overflow pipelines of a feeding unit and a forced circulation crystallizer, calculating a theoretical overfeeding value, and accurately controlling the concentration of potassium chloride in potassium-containing mother liquor entering a continuous regulator;
s520, performing off-line detection, namely sampling the material in the forced circulation crystallizer to detect the potassium content of the material;
s530, removing sodium chloride, centrifuging the excessive sodium chloride in the potassium-containing mother liquor by using a centrifugal filtering device, and returning the precipitated sodium chloride to the forced circulation crystallizer for continuous evaporation.
9. The method for high-quality salt separation of fly ash water scrubbing liquid according to claim 8, wherein in the online monitoring of step S510, the concentration of potassium chloride in the potassium-containing mother liquid entering the continuous regulator is controlled to be 15% to 22%.
10. The high-quality salt separation method for the fly ash water washing liquid according to claim 9, wherein the step S600 comprises the steps of:
s610, mixing and cooling, and mixing the adjusted potassium-containing mother liquor with the potassium-containing mother liquor circulating in the continuous crystallizer to reduce the superheat degree.
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