CN117509784A - System and method for recycling salt compounds in wastewater - Google Patents
System and method for recycling salt compounds in wastewater Download PDFInfo
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- CN117509784A CN117509784A CN202311459126.0A CN202311459126A CN117509784A CN 117509784 A CN117509784 A CN 117509784A CN 202311459126 A CN202311459126 A CN 202311459126A CN 117509784 A CN117509784 A CN 117509784A
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- 239000002351 wastewater Substances 0.000 title claims abstract description 106
- -1 salt compounds Chemical class 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000004064 recycling Methods 0.000 title claims abstract description 12
- 230000008014 freezing Effects 0.000 claims abstract description 30
- 238000007710 freezing Methods 0.000 claims abstract description 30
- 238000002425 crystallisation Methods 0.000 claims abstract description 28
- 230000008025 crystallization Effects 0.000 claims abstract description 28
- 239000013505 freshwater Substances 0.000 claims abstract description 25
- 238000007791 dehumidification Methods 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 51
- 239000007788 liquid Substances 0.000 claims description 36
- 239000012452 mother liquor Substances 0.000 claims description 33
- 239000013078 crystal Substances 0.000 claims description 19
- 238000001816 cooling Methods 0.000 claims description 15
- 238000012546 transfer Methods 0.000 claims description 15
- 238000005507 spraying Methods 0.000 claims description 13
- 239000000945 filler Substances 0.000 claims description 12
- 230000001502 supplementing effect Effects 0.000 claims description 8
- 239000000110 cooling liquid Substances 0.000 claims description 7
- 229920006395 saturated elastomer Polymers 0.000 claims description 6
- 239000002562 thickening agent Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000012856 packing Methods 0.000 claims description 2
- 238000005057 refrigeration Methods 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 5
- 239000000498 cooling water Substances 0.000 abstract description 4
- 238000011161 development Methods 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 abstract description 3
- 230000001737 promoting effect Effects 0.000 abstract description 3
- 238000011084 recovery Methods 0.000 abstract description 3
- 238000004065 wastewater treatment Methods 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 230000010354 integration Effects 0.000 abstract description 2
- 239000003507 refrigerant Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 26
- 239000012141 concentrate Substances 0.000 description 17
- 239000007789 gas Substances 0.000 description 16
- 239000011550 stock solution Substances 0.000 description 9
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910052938 sodium sulfate Inorganic materials 0.000 description 6
- 235000011152 sodium sulphate Nutrition 0.000 description 6
- 239000002826 coolant Substances 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- RSIJVJUOQBWMIM-UHFFFAOYSA-L sodium sulfate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[O-]S([O-])(=O)=O RSIJVJUOQBWMIM-UHFFFAOYSA-L 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 239000003245 coal Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000012047 saturated solution Substances 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 150000004691 decahydrates Chemical class 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/22—Treatment of water, waste water, or sewage by freezing
-
- 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
Abstract
The application relates to a system and a method for recycling salt compounds in wastewater, belonging to the technical field of zero emission and resource utilization of high-salt wastewater, wherein the system for recycling salt compounds in wastewater comprises CO 2 A cold and hot combined supply system, a waste water humidifying and dehumidifying concentration system and a concentrated solution freezing and crystallizing system. The invention couples three key technologies of refrigeration, humidification, dehumidification and crystallization, realizes the integration of cold and hot circulation in the system, does not need external steam and cooling water, achieves the cooperative recovery and resource utilization of fresh water, salt, heat and cold, can greatly reduce the treatment cost of high-salt wastewater, adopts safe, economic and environment-friendly natural refrigerant, has large refrigeration capacity, high efficiency, compactness and small occupied area, solves the problems of high treatment cost, high operation cost and large occupied area of the existing system, and greatly reduces the treatment cost of the high-salt wastewaterThe high-salt wastewater treatment cost has excellent environmental protection and economic benefit for promoting the development of circular economy.
Description
Technical Field
The application relates to the technical field of zero discharge and resource utilization of high-salt wastewater, in particular to a system and a method for recycling salt compounds in wastewater.
Background
In the fields of industries such as coal mine, coal chemical industry, steel, cement, chemical industry and the like, the method for treating the NOx in the flue gasIn the course of SOx, a large amount of Na is produced 2 SO 4 、NaCl、NaNO 3 The prior waste water treatment method includes flue gas spray drying, desulfurization waste water introduction and deslagging system, coal yard spraying and other modes, and belongs to pollutant transfer. In fact, sodium sulfate and the like in the high-concentration industrial salt-containing wastewater can be used as raw materials in the alkali production industry, and the zero-emission technology not only can recycle fresh water, but also can recycle the useful components. At present, salt separation crystallization modes mainly adopted for recycling desulfurization wastewater are evaporation crystallization and freezing crystallization modes. The evaporative crystallization generally uses external steam to provide heat, while the freeze crystallization generally uses only the evaporative side of the refrigerator for refrigeration. The two modes consume a large amount of high-grade energy sources such as steam, electricity and the like, so that the treatment cost is too high, the operation cost is high, the occupied area is large, the enthusiasm of enterprises for promoting the development of recycling economy is seriously influenced, and therefore, how to reduce the energy consumption and recycle low carbon is a problem to be solved.
Disclosure of Invention
The invention mainly aims to provide a system and a method for recycling salt compounds in wastewater, and aims to solve at least one technical problem.
In order to achieve the above object, the present invention provides a system for recovering salt compounds in wastewater, comprising: CO 2 The cold and hot combined supply system is provided with a heat source and a cold source; the waste water humidifying, dehumidifying and concentrating system comprises a humidifying tower and a dehumidifying tower, wherein the heat source heats waste water in the humidifying tower to generate steam and form concentrated solution, and the dehumidifying tower condenses the steam to form water; and the concentrated solution freezing and crystallizing system is used for receiving the concentrated solution, and the cold source is used for forcedly cooling the concentrated solution in the concentrated solution freezing and crystallizing system to separate out crystals.
In some embodiments of the invention, the concentrate liquid cooled frozen crystal system comprises: a freezing crystallization unit formed with a cooling liquid inlet and a cooling liquid outlet, and a concentrated liquid inlet and a concentrated liquid outlet; and the thickener, the centrifugal machine and the dryer are sequentially connected with the concentrated solution outlet.
In some embodiments of the invention, the centrifuge is formed with a mother liquor outlet, the mother liquor outlet is sequentially connected with a mother liquor tank and a mother liquor pump, and the other end of the mother liquor pump is connected with the concentrated liquor inlet and/or the wastewater humidification and dehumidification concentration system.
In some embodiments of the present invention, a heat transfer pipe is provided in the dehumidification tower, the heat transfer pipe being formed with a waste water filler and a waste water discharge port, the waste water filler being connected to a waste water source and the mother liquor pump, the waste water discharge port being connected to the humidification tower.
In some embodiments of the invention, the dryer is formed with a first water outlet, a second water outlet is formed at the lower part of the dehumidifying tower, and a fresh water pump is commonly connected with the first water outlet and the second water outlet.
In some embodiments of the invention, a water supplementing port is arranged at the lower part of the humidifying tower, and the outlet of the fresh water pump is connected with the water supplementing port.
In some embodiments of the invention, a spraying device, a filler and a liquid storage tank are sequentially arranged in the humidifying tower from top to bottom, a circulating pump is connected between the spraying device and the liquid storage tank, and the circulating pump pumps the wastewater in the liquid storage tank to the spraying device after heat exchange of the heat source.
In some embodiments of the invention, the top of the humidifying tower forms a vent that communicates with the humidifying tower and the dehumidifying tower.
In some embodiments of the invention, an air inlet is formed between the packing and the reservoir of the humidification tower, and a fan is mounted to the exhaust.
According to another aspect of the present invention, there is provided a method for recovering salt compounds from wastewater, concentrating and crystallizing wastewater to obtain fresh water by using the above system for recovering salt compounds from wastewater, the method for recovering salt compounds from wastewater comprising the steps of: preparing wastewater in a humidifying tower; heating the wastewater by using a heat source to evaporate the wastewater and generate steam, concentrating the wastewater to be saturated to obtain concentrated solution, and condensing the steam into water in a dehumidification tower; the concentrated liquid cooling freezing crystal system receives concentrated liquid, and the concentrated liquid in the concentrated liquid freezing crystal system is forcedly cooled to 0-5 ℃ by using a cold source, so that crystals are separated out.
Embodiments of the present application provide a method for utilizing CO 2 Cold and hot combined supply system (CO) 2 Refrigeration system) for recovering salt compounds in wastewater for providing heat and cold for crystallization process of sodium sulfate solution, in particular to a system for recovering salt compounds in wastewater by using CO 2 High temperature and high pressure CO discharged from compressor of refrigeration system 2 Heating sodium sulfate stock solution, crystallizing sodium sulfate by using CO 2 The chilled water supplied by the evaporator of the refrigerating system is combined with the closed humidifying tower and the dehumidifying tower, so that an energy-saving method for recovering salt compounds in wastewater is provided, and outdoor air can be fully utilized to cool and evaporate high-temperature stock solution, so that natural cooling, evaporation and concentration are realized; the sodium sulfate stock solution after cooling and concentrating enters a concentrated solution freezing and crystallizing system to carry out crystallization separation, and high-purity decahydrate Na is separated 2 SO 4 The crystals are dried to obtain high-purity Na 2 SO 4 A solid; most of the freezing crystallization mother liquor flows back to the freezing crystallization unit, and the small part of the freezing crystallization mother liquor is mixed with the sodium sulfate stock solution to be used for cooling water vapor in the solution evaporation process, and the condensed water is used as water for a cooling tower and is supplied to desalted water or other process links; therefore, the integrated cold and hot circulation in the system is realized, steam and cooling water are not required to be supplied, the cooperative recovery and resource utilization of fresh water, salt, heat and cold are realized, the high-salt wastewater treatment cost is greatly reduced, and the method has excellent environmental protection and economic benefits for promoting the development of recycling economy.
Compared with the prior art, the invention achieves the following technical effects:
1. the invention couples three key technologies of refrigeration, humidification, dehumidification and crystallization, realizes the integration of cold and hot circulation in the system, does not need external steam and cooling water supply, achieves the cooperative recovery and resource utilization of fresh water, salt, heat and cold, and can greatly reduce the treatment cost of high-salt wastewater.
2. The refrigerating machine of the freezing crystallization system adopts a safe, economical and environment-friendly natural refrigerant, has large refrigerating capacity, can reduce the size of a compressor, has high efficiency and compactness, and occupies small area.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram of the overall structure of a system for recovering salt compounds in wastewater according to an embodiment of the present application.
The reference numerals in the drawings are as follows: 1. CO 2 A cold and hot combined supply system; 2. a wastewater humidification, dehumidification and concentration system; 3. a concentrated solution freezing and crystallizing system; 4. a gas cooler; 5. an expansion valve; 6. CO 2 A secondary cooling system; 7. an evaporator; 8. CO 2 A compressor; 9. a chilled water inlet line; 10. a chilled water outlet line; 11. a freeze crystallization unit; 12. a circulating solution pipeline; 13. a saturated solution pipeline; 14. a circulation pump; 15. a humidifying tower; 16. a dehumidifying tower; 17. a spraying device; 18. a filler; 19. an air inlet; 20. a liquid storage tank; 21. a blower; 22. a first drain outlet; 23. a raw liquid pump; 24. a heat transfer tube; 25. a discharge pump; 26. a thickener; 27. a centrifuge; 28. a mother liquor tank; 29. a mother liquid pump; 30. a mother liquor return line; 31. a dryer; 32. a fresh water pump; 33. a water supplementing pipeline; 34. and (5) water supplementing.
Detailed Description
It should be understood that the described embodiments are merely some, but not all, of the embodiments of the present application. All other embodiments, based on the embodiments herein, which would be apparent to one of ordinary skill in the art without making any inventive effort, are intended to be within the scope of the present application.
When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the accompanying claims.
In the description of the present application, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context. Furthermore, in the description of the present application, unless otherwise indicated, "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.
The embodiment of the application discloses a system for recycling salt compounds in wastewater. As shown in FIG. 1, the system for recovering salt compounds in wastewater comprises CO 2 A cold and hot combined supply system 1, a waste water humidifying, dehumidifying and concentrating system 2 and a concentrated solution freezing and crystallizing system 3.
In some embodiments of the invention, as shown in FIG. 1, CO 2 The combined cooling and heating system 1 comprises a gas cooler 4, an expansion valve 5, an evaporator 7 and CO which are sequentially connected in series 2 A compressor 8; wherein the gas cooler 4 serves as a heat source and the evaporator 7 serves as a cold source.
In one embodiment, CO is also externally connected between the gas cooler 4 and the expansion valve 5 2 The secondary cooling system 6 cools the cooled CO through the gas cooler 4 2 Returning to the expansion valve 5, and when the design temperature of the inlet of the expansion valve 5 is not reached, using external CO 2 The secondary cooling system 6 cools CO 2 And (5) reducing the temperature to the design temperature.
In some embodiments of the present invention, as shown in fig. 1, the wastewater humidification dehumidification concentration system 2 includes a humidification tower 15 and a dehumidification tower 16, wherein the humidification tower 15 is used for evaporation of water in the wastewater to obtain a concentrate, and the dehumidification tower 16 is used for condensing steam to form water.
Specifically, a spray device 17, a filler 18 and a liquid storage tank 20 are sequentially arranged in the humidifying tower 15 from top to bottom in the embodiment, and a circulating pump 14 is arranged between the spray device 17 and the liquid storage tank 20; the top of the humidifying tower 15 is provided with an exhaust port which is communicated with the humidifying tower 15 and the dehumidifying tower 16.
It should be noted that two chambers separated from each other are formed in the gas cooler 4, wherein one chamber is connected in series with the CO2 cold and hot combined supply system 1, the other chamber and the spraying device 17 are sequentially connected to the outlet of the circulating pump 14, the inlet of the circulating pump 14 is connected to the bottom of the liquid storage tank 20, that is, the liquid storage tank 20, the circulating pump 14, the gas cooler 4 and the spraying device 17 are connected in series through the circulating solution pipeline 12.
The circulating pump 14 pumps the wastewater in the liquid storage tank 20 to the spraying device 17 after passing through the gas cooler 4, and the wastewater is treated with high-temperature high-pressure CO at the gas cooler 4 2 The gas exchanges heat to raise the temperature of the waste water, the high-temperature waste water is sprayed out from a spray head of the spray device 17, and is contacted with air in a flowing way to perform cold and heat exchange to generate steam, the steam volatilizes to take away moisture, the concentrated waste water reenters the water storage tank, the steam enters the dehumidification tower 16 through the air outlet, and finally saturated concentrated solution is obtained in the water storage tank, and fresh water is obtained in the dehumidification tower 16.
In one embodiment, the humidifying tower 15 is provided with an air inlet 19 between the filler 18 and the liquid storage tank 20, and a fan 21 is arranged at the exhaust port, and the fan 21 is matched with the air inlet 19 to accelerate the evaporation of water in the wastewater and the efficiency of discharging steam into the dehumidifying tower 16.
In one embodiment, the bottom of the humidifying tower 15 is further formed with a first drain 22 for draining the dirt in the liquid storage tank 20, specifically, the first drain 22 in this embodiment is formed on a pipe between the circulation pump 14 and the liquid storage tank 20, and in other embodiments, the first drain 22 may be directly disposed on the bottom of the humidifying tower 15, i.e. the liquid storage tank 20, which is not limited herein.
In one embodiment, a heat transfer tube 24 is arranged in the dehumidification tower 16, the heat transfer tube 24 is provided with a waste water filling port and a waste water discharging port, the waste water filling port is connected with a waste water source, and the waste water discharging port is connected with the humidification tower 15; the waste water enters the humidifying tower 15 through the heat transfer pipe 24, and the waste water can be stored in the heat transfer pipe 24 firstly, so that the waste water can be used for cooling steam in the current waste water evaporation process, and the waste water of the next cycle can be preheated preliminarily.
Specifically, the waste water discharge port in this embodiment is connected to the pipe between the circulation pump 14 and the liquid storage tank 20 through the pipe and the raw liquid pump 23, and in other embodiments, the waste water discharge port may be directly connected to the bottom of the humidifying tower 15, that is, the liquid storage tank 20, which is not limited herein; the heat transfer pipe 24 is a tube array heat exchanger, wet air (steam) is arranged outside the tube array of the dehumidifying tower 16, wastewater stock solution is arranged in the tube array, and heat exchange is carried out between the wastewater stock solution and the wet air from top to bottom.
In one embodiment, a second water outlet is formed in the lower portion of the dehumidification tower 16, and a fresh water pump 32 is connected to the second water outlet for discharging fresh water generated by condensing steam.
In one embodiment, a water replenishment port 34 is provided in the lower portion of the humidifying tower 15 for supplying the humidifying tower 15.
In one embodiment, the outlet of fresh water pump 32 is also connected to a water replenishment port 34 via a water replenishment line 33, so that a portion of the fresh water in dehumidification tower 16 is directly used to feed humidification tower 15 and another portion of the fresh water is discharged for use.
In some embodiments of the present invention, as shown in fig. 1, the concentrate freeze crystallization system 3 includes a freeze crystallization unit 11, the freeze crystallization unit 11 being formed with a coolant inlet and a coolant outlet and a concentrate inlet and a concentrate outlet; it will be appreciated that the freeze crystallization unit 11 has a chamber formed therein in communication with the concentrate inlet and the concentrate outlet, and that another chamber is provided outside the chamber in communication with the coolant inlet and the coolant outlet.
It is worth mentioning that two chambers separated from each other are formed in the evaporator 7, one of which is connected in series with CO 2 In the combined cooling and heating system 1, the other chamber forms a loop with the cooling liquid inlet and the cooling liquid outlet of the freezing and crystallizing unit 11 through the freezing water inlet pipeline 9 and the freezing water outlet pipeline 10, and can be driven by a pump.
The concentrated solution obtained in the humidifying tower 15 enters the freezing and crystallizing unit 11 through a concentrated solution inlet, the evaporator 7 pumps cooling liquid to the freezing and crystallizing unit 11 through a freezing water inlet pipeline 9, so that the concentrated solution is forcedly cooled, the temperature is reduced to 0-5 ℃, and crystals are precipitated.
In one embodiment, the outlet end of the concentrated solution is sequentially connected with a discharge pump 25, a thickener 26, a centrifuge 27 and a dryer 31, the low-temperature concentrated solution is discharged from the freezing crystallization unit 11, enters the thickener 26 for adjustment, is conveyed to the centrifuge 27, and is thickened, centrifuged and settled to obtain salt compound crystals and mother liquor, and the salt compound crystals are dried in the dryer 31 to form a powder product.
In one embodiment, the centrifuge 27 is formed with a mother liquor outlet connected in turn to a mother liquor tank 28 and a mother liquor pump 29, the other end of the mother liquor pump 29 being connected to a concentrate inlet and/or the wastewater humidification dehumidification concentration system 2.
Specifically, the other end of the mother liquor pump 29 in the present embodiment is connected to the concentrate inlet through a mother liquor return line 30, and the other end of the mother liquor pump 29 is connected to the waste water filler; and one part of mother liquor flows back to the cooling crystallization unit, and the other part of mother liquor is mixed with the wastewater stock solution, enters the dehumidification tower 16 to cool steam, and accelerates the steam to be condensed into fresh water.
In one embodiment, a second drain outlet is also arranged at the bottom of the mother liquor tank 28 for draining the mother liquor tank 28; specifically, the second drain in this embodiment is provided on a pipe at the outlet end of the mother liquor pump 29, and in other embodiments, the second drain may be provided directly at the bottom of the mother liquor tank 28, which is not limited herein.
In one embodiment, the dryer 31 is formed with a first water outlet, and the first water outlet and the second water outlet are connected together with a fresh water pump 32, and fresh water or discharged water generated during the drying of the salt compound crystals by the dryer 31 is utilized or delivered to the humidifying tower 15.
In some embodiments of the present invention, as shown in fig. 1, the concentrate inlet is connected to the bottom of the reservoir 20, i.e., the saturated solution line 13 connects the concentrate inlet to the bottom of the reservoir 20 to deliver the concentrate in the reservoir 20 directly to the freeze crystallization unit 11.
Specifically, the concentrate inlet in the present embodiment is connected to the pipe between the circulation pump 14 and the gas cooler 4 through a pipe, and the concentrate in the reservoir 20 is pumped to the freezing and crystallizing unit 11 by the circulation pump 14; in other embodiments, the concentrate inlet may also be connected directly to the bottom of the reservoir 20 via tubing and pumps, without limitation.
In some embodiments of the present invention, as shown in fig. 1, a valve may be provided on each junction line, i.e., each leg of each tee or four-way, and the material (fluid) is controlled to be delivered from one location to another location, from two locations to another location, from one location to two other locations, etc., by controlling the partial or full opening of each valve, depending on the actual needs of each stage of production.
Taking the first tee in the direction of the outlet of the circulation pump 14 as an example, the tee may be provided with a valve on each of the branch close to the gas cooler 4 and the branch close to the freeze crystallization unit 11; by controlling the opening of the valve on the branch close to the gas cooler 4, the wastewater in the liquid storage tank 20 can enter the gas cooler 4 and the spraying device 17 through the circulating pump 14; by controlling the opening of the valve on the branch close to the freeze crystallization unit 11, it is achieved that the concentrate in the reservoir 20 enters the freeze crystallization unit 11 via the circulation pump 14. Other tee joints or four joints are arranged in a same way, so that the fluid can be conveyed in a set direction in a specific production stage, and each valve comprises, but is not limited to, a manual valve or an electromagnetic valve and the like, and is not limited herein.
The embodiment also provides a method for recovering the salt compounds in the wastewater, which uses the system for recovering the salt compounds in the wastewater to concentrate and crystallize the wastewater and obtain fresh water, and the wastewater stock solution comprises but is not limited to Na-containing water 2 SO 4 Or other high-salt industrial wastewater with the solubility obviously reduced along with the temperature reduction, the following components contain Na 2 SO 4 For example, the method for recovering salt compounds in the wastewater comprises the following steps:
1) Na-containing solution is fed into the reservoir 20 through the wastewater filler, the heat transfer pipe 24, the wastewater discharge port and the raw solution pump 23 2 SO 4 And replenishing the lower temperature wastewater in the heat transfer tube 24.
2) The wastewater is cooled by a circulating pump 14 and gasThe cooler 4, the spraying device 17 and the filler 18 enter the liquid storage tank 20 to form circulation, and the high-temperature high-pressure CO of the gas cooler 4 2 The gas heats the waste water to generate steam in the humidifying tower 15, and the waste water is concentrated until the waste water becomes saturated Na SO 4 A solution.
Meanwhile, steam enters the dehumidifying tower 16 through the action of the exhaust port matched with the fan 21 and the air inlet 19, and is condensed into fresh water through the heat exchange action of the waste water in the heat transfer pipe 24, and the fresh water is discharged and utilized or is supplied to the humidifying tower 15 through the fresh water pump 32, the water supplementing pipeline 33 and the water supplementing port 34.
3) Saturated Na SO 4 The solution enters the freezing and crystallizing unit 11 through the circulating pump 14 and the saturated solution pipeline 13, and the cooled CO of the evaporator 7 2 Heat exchange with chilled water to cool the chilled water, the chilled water circulates in a freezing crystallization unit 11 through a chilled water inlet pipeline 9 and a chilled water outlet pipeline 10 to forcedly cool saturated Na SO 4 The solution is heated to 0-5 ℃ and sodium sulfate decahydrate crystals are separated out.
4) Low temperature saturation of Na SO 4 The solution is discharged from the freezing and crystallizing unit 11, enters the thickener 26 for adjustment, is conveyed to the centrifuge 27, is thickened, centrifuged and settled to obtain sodium sulfate decahydrate crystals and mother liquor, and the sodium sulfate decahydrate crystals are dried by the dryer 31 to form anhydrous sodium sulfate products.
Meanwhile, in the process of drying the sodium sulfate decahydrate crystal by the dryer 31, the produced fresh water or discharged water is utilized or supplied to the humidifying tower 15; and, a part of the mother liquor is returned to the cooling crystallization unit, and the other part of the mother liquor is mixed with the wastewater stock solution and enters the heat transfer pipe 24 of the dehumidification tower 16 to cool the steam.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. A system for recovering salt compounds from wastewater, comprising:
CO 2 the cold and hot combined supply system is provided with a heat source and a cold source;
the waste water humidifying, dehumidifying and concentrating system comprises a humidifying tower and a dehumidifying tower, wherein the heat source heats waste water in the humidifying tower to generate steam and form concentrated solution, and the dehumidifying tower condenses the steam to form water;
and the concentrated solution freezing and crystallizing system is used for receiving the concentrated solution, and the cold source is used for forcedly cooling the concentrated solution in the concentrated solution freezing and crystallizing system to separate out crystals.
2. The system for recovering salt compounds from wastewater of claim 1, wherein the concentrated liquid-cooled frozen crystal system comprises:
a freezing crystallization unit formed with a cooling liquid inlet and a cooling liquid outlet, and a concentrated liquid inlet and a concentrated liquid outlet;
and the thickener, the centrifugal machine and the dryer are sequentially connected with the concentrated solution outlet.
3. The system for recycling salt compounds in waste water according to claim 2, wherein the centrifuge is formed with a mother liquor outlet, the mother liquor outlet is sequentially connected with a mother liquor tank and a mother liquor pump, and the other end of the mother liquor pump is connected with the concentrated liquor inlet and/or the waste water humidifying and dehumidifying concentration system.
4. A system for recovering salt compounds from wastewater as claimed in claim 3, wherein a heat transfer tube is provided in said dehumidification tower, said heat transfer tube being formed with a wastewater filler and a wastewater discharge port, said wastewater filler being connected to a wastewater source and said mother liquor pump, said wastewater discharge port being connected to said humidification tower.
5. The system for recovering salt compounds from wastewater according to claim 2, wherein the dryer is formed with a first water outlet, a second water outlet is formed at a lower portion of the dehumidifying tower, and a fresh water pump is commonly connected to the first water outlet and the second water outlet.
6. The system for recovering salt compounds from wastewater as claimed in claim 5, wherein a water supplementing port is arranged at the lower part of the humidifying tower, and an outlet of the fresh water pump is connected with the water supplementing port.
7. The system for recycling salt compounds in wastewater according to claim 1, wherein a spraying device, a filler and a liquid storage tank are sequentially arranged in the humidifying tower from top to bottom, a circulating pump is connected between the spraying device and the liquid storage tank, and the circulating pump pumps the wastewater in the liquid storage tank to reach the spraying device after heat exchange of the heat source.
8. The system for recovering salt compounds from wastewater of claim 7, wherein a vent is formed at the top of said humidification tower, said vent communicating with said humidification tower and said dehumidification tower.
9. The system for recovering salt compounds from wastewater of claim 8, wherein said humidifying tower is provided with an air inlet between said packing and said reservoir, and said air outlet is provided with a fan.
10. A method for recovering salt compounds in wastewater, which is characterized in that the system for recovering salt compounds in wastewater according to any one of claims 1-9 is used for concentrating and crystallizing wastewater to obtain fresh water, and the method for recovering salt compounds in wastewater comprises the following steps:
preparing wastewater in a humidifying tower;
heating the wastewater by using a heat source to evaporate the wastewater and generate steam, concentrating the wastewater to be saturated to obtain concentrated solution, and condensing the steam into water in a dehumidification tower;
the concentrated liquid cooling freezing crystal system receives concentrated liquid, and the concentrated liquid in the concentrated liquid freezing crystal system is forcedly cooled to 0-5 ℃ by using a cold source, so that crystals are separated out.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311459126.0A CN117509784A (en) | 2023-11-03 | 2023-11-03 | System and method for recycling salt compounds in wastewater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311459126.0A CN117509784A (en) | 2023-11-03 | 2023-11-03 | System and method for recycling salt compounds in wastewater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117509784A true CN117509784A (en) | 2024-02-06 |
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ID=89757763
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311459126.0A Pending CN117509784A (en) | 2023-11-03 | 2023-11-03 | System and method for recycling salt compounds in wastewater |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117509784A (en) |
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2023
- 2023-11-03 CN CN202311459126.0A patent/CN117509784A/en active Pending
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