Chemical high-concentration brine treatment system

Abstract

The invention belongs to the technical field of environmental protection equipment, and particularly relates to a chemical high-concentration brine treatment system which comprises a front-section treatment device, a concentration and separation device, a sodium chloride solution treatment device and a sodium sulfate solution treatment device. According to the method, hardness ions and organic matters in the high-concentration brine can be efficiently removed, effective separation of salt can be realized, resources in the high-concentration brine can be recovered and utilized to the greatest extent, sodium chloride and sodium sulfate products recovered by the method are high in purity, and meanwhile, salt recovery does not depend on evaporative crystallization or simple physical and chemical treatment. The treatment cost of the chemical strong brine is reduced, the resource utilization rate is increased, and the environmental protection concept is met.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection equipment technology, specifically relating to a chemical high-concentration brine treatment system. Background Technology

[0002] The treatment of high-concentration brine in chemical industries has always been a technical challenge. Traditional treatment methods are not only energy-intensive and inefficient, but also have low resource recovery rates, placing a heavy burden on enterprise operations and causing significant environmental impacts. Existing treatment systems often struggle to completely remove hardness ions and organic matter at the front end, increasing the difficulty of subsequent steps. Concentration and separation units frequently experience operational instability due to clogging and wear, while the treatment processes for sodium chloride and sodium sulfate solutions are complex, cumbersome, and inefficient. More importantly, once a system malfunctions, there is often a lack of rapid and effective countermeasures, leading to production interruptions, increased equipment maintenance costs, and shortened equipment lifespan. Therefore, there is an urgent need for a new type of high-concentration brine treatment system that can efficiently remove impurities, achieve efficient resource recovery and utilization, possess strong fault response capabilities, ensure continuous and stable system operation, reduce enterprise operating costs, improve resource utilization, and meet environmental protection requirements. Summary of the Invention

[0003] In view of this, the present invention provides a chemical high-concentration brine treatment system that can efficiently remove hardness ions and organic matter from high-concentration brine and achieve effective salt separation. It also maximizes the recovery and utilization of resources, improves the purity of sodium chloride and sodium sulfate products, and eliminates reliance on evaporation crystallization or simple physicochemical treatments for salt recovery. This invention reduces processing costs, improves resource utilization, and aligns with current environmental protection principles.

[0004] To achieve the above-mentioned technical objectives, the specific technical solution adopted by the present invention is as follows: A chemical high-concentration brine treatment system, comprising: The pre-treatment device removes suspended solids and organic matter from the high-concentration brine, pre-filters and concentrates the high-concentration brine, and removes hardness ions from the high-concentration brine. The concentration and separation device receives the effluent from the pretreatment device and processes the high-concentration brine as follows: filters out water using reverse osmosis, removes hardness ions using a sodium bed, reduces alkalinity using a decarbonization process, removes COD using activated carbon adsorption, reduces residual divalent ions using a chelate bed, and separates the brine into Na2SO4 solution and NaCl solution using nanofiltration. A sodium chloride solution treatment device receives the NaCl solution and processes the NaCl solution by: evaporating water using an evaporator, separating solid and liquid components using a centrifuge, and drying the NaCl into granules using a vibrating fluidized bed. A sodium sulfate solution processing device receives the Na2SO4 solution and processes the Na2SO4 solution by: evaporating water using an evaporator, separating solid and liquid components using a centrifuge, and drying the Na2SO4 into granules using a vibrating fluidized bed.

[0005] Furthermore, in order to achieve low-cost, efficient, and orderly separation of salts in high-concentration brine from chemical processes, the pretreatment device removes hardness ions from the high-concentration brine based on a weak acid sodium bed; the concentration and separation device includes: The secondary reverse osmosis unit is connected to the outlet of the weak acid sodium bed at its inlet, and filters out the water from the high-concentration brine. The decarbonation tower is connected to the concentrate side of the secondary reverse osmosis unit at its inlet to reduce the alkalinity of the high-concentration brine. An activated carbon tower, with its inlet connected to the outlet of the decarbonization tower, removes COD from the high-concentration brine. A weak acid chelating bed, with its inlet connected to the outlet of the decarbonation tower, reduces the residual amount of divalent ions in the high-concentration brine. The first-stage nanofiltration unit is connected to the effluent from the weak acid chelate bed, separating the high-concentration brine into Na2SO4 solution and NaCl solution.

[0006] Furthermore, to improve the solution separation rate and further concentrate the sodium chloride solution, the concentration and separation device also includes: The three-stage reverse osmosis unit has its inlet connected to the clear water side of the first-stage nanofiltration unit and its concentrate side connected to the sodium chloride solution treatment device. The secondary nanofiltration unit has its inlet connected to the concentrate side of the primary nanofiltration unit, its clear water side connected to the inlet of the tertiary reverse osmosis unit, and its concentrate side connected to the sodium sulfate solution treatment device.

[0007] Furthermore, in order to achieve rapid, efficient, and low-cost granulation of NaCl in concentrated NaCl solution, the sodium chloride solution treatment device includes: The first evaporator is connected to the concentrate side of the third-stage RO system to evaporate the water in the NaCl solution; A NaCl centrifuge receives the solid-liquid phase discharge from the first evaporator and separates out moist NaCl. A NaCl vibrating fluidized bed receives the moist NaCl, dries the moist NaCl, and outputs dried NaCl particles.

[0008] Furthermore, in order to achieve rapid, efficient, and low-cost granulation of Na2SO4 in concentrated Na2SO4 solution, the sodium sulfate solution treatment device includes: The second evaporator is connected to the concentrate side of the secondary nanofiltration unit to evaporate the water in the Na2SO4 solution; The Na2SO4 centrifuge receives the solid-liquid phase discharge from the second evaporator and separates out moist Na2SO4. A Na2SO4 vibrating fluidized bed receives the moist Na2SO4, dries the moist Na2SO4, and outputs dried Na2SO4 particles.

[0009] To further achieve complete salt recovery from high-concentration brine, the chemical high-concentration brine treatment system also includes a mother liquor treatment device, which comprises: The third evaporator receives the mother liquor separated by the NaCl centrifuge and the Na2SO4 centrifuge and evaporates and separates the mixed salt solution. A filter press receives the mixed salt solution and filters out the mixed salt.

[0010] In order to improve the output efficiency of the sodium chloride solution treatment device, reduce the operating cost of the sodium chloride solution treatment device, increase the NaCl recovery rate in high-concentration brine, and shorten the residence time of concentrated NaCl solution and mother liquor, the first evaporator is a two-stage evaporator. If the TDS of the centrifuged liquid from the NaCl solution centrifuge is greater than or equal to 100,000 mg / L and less than 200,000 mg / L, the centrifuged liquid is transported to the inlet of the secondary evaporator of the first evaporator. If the TDS of the centrifuged liquid from the NaCl solution centrifuge is less than 100,000 mg / L, the centrifuged liquid is transported to the inlet of the first-stage evaporator of the first evaporator. If the TDS of the centrifuged liquid from the NaCl solution centrifuge is greater than 230,000 mg / L, the centrifuged liquid is transferred to the third evaporator.

[0011] In order to improve the output efficiency of the sodium sulfate solution treatment unit, reduce the operating cost of the sodium sulfate solution treatment unit, increase the recovery rate of Na2SO4 in high-concentration brine, and shorten the residence time of Na2SO4 concentrated solution and mother liquor, the second evaporator is a two-stage evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is greater than or equal to 130,000 mg / L and less than 230,000 mg / L, the centrifuged liquid is transported to the inlet of the secondary evaporator of the second evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is less than 130,000 mg / L, the centrifuged liquid is transported to the inlet of the first-stage evaporator of the second evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is greater than 250,000 mg / L, the centrifuged liquid is transferred to the third evaporator. Furthermore, in order to improve the processing efficiency of the concentration and separation device, the front-end treatment device uses an ultrafiltration unit and a front-end RO unit to initially filter and concentrate the high-concentration brine. Furthermore, to ensure the safety of the precision membrane, a security filter is installed at the inlet of both the secondary reverse osmosis unit and the secondary nanofiltration unit.

[0012] By adopting the above technical solution, the present invention can bring the following beneficial effects: This invention employs a reasonable water treatment approach to achieve zero discharge of concentrated chemical brine, while simultaneously recovering all sodium chloride and sodium sulfate. The concentration and separation device of the present invention adopts a reasonable combination method, which has high separation efficiency, high concentration efficiency, low failure rate and low maintenance cost. The sodium chloride solution treatment device and sodium sulfate treatment device of the present invention adopt a reasonable combination, which has high treatment efficiency and low energy consumption; This invention employs a flexible treatment method for centrifuged liquid, which can improve the yield of pure sodium chloride and sodium sulfate, while ensuring operating costs and reducing corrosion of storage containers caused by the retention of concentrated solutions or mother liquor, thereby reducing overall maintenance costs. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the connection method of a chemical high-concentration brine treatment system according to a specific embodiment of the present invention; The system includes: 1. Pretreatment unit; 2. UF+RO treatment unit; 3. RO concentrate tank; 4. Weak acid sodium bed; 5. Sodium bed effluent tank; 6. Reverse osmosis security filter; 7. Secondary reverse osmosis unit; 8. Secondary reverse osmosis unit concentrate tank; 9. Decarbonization tower; 10. Decarbonization tower effluent tank; 11. Activated carbon tower; 12. Activated carbon tower effluent tank; 13. Weak acid chelation bed; 14. Chelation bed effluent tank; 15. Primary nanofiltration unit; 16. Nanofiltration product tank; 17. Tertiary reverse osmosis unit; 18. Tertiary reverse osmosis unit concentrate tank; 19. Primary evaporator; 20. Secondary evaporator; 21. NaCl solution centrifuge; 22. NaCl vibrating fluidized bed; 23. NaCl discharge hopper; 24. NaCl packaging machine; 25. First induced draft fan; 26. First bag filter; 27. NaCl... 1. Centrifuge filtrate tank; 28. Aging mother liquor collection tank; 29. ​​Single-stage evaporator; 30. Plate and frame filter press; 31. Salt mixing hopper; 32. First-stage nanofiltration unit concentrate tank; 33. Second-stage nanofiltration unit security filter; 34. Second-stage nanofiltration unit; 35. Second-stage nanofiltration unit concentrate tank; 36. Third-stage evaporator; 37. Fourth-stage evaporator; 38. Na2SO4 centrifuge; 39. Na2SO4 vibrating fluidized bed; 40. Na2SO4 discharge hopper; 41. Na2SO4 packaging machine; 42. Second induced draft fan; 43. Second bag filter; 44. Na2SO4 centrifuge filtrate tank; 45. First pipeline; 46. Second pipeline; 47. Third pipeline; 48. Fourth pipeline; 49. Eighth pipeline; 50. Fifth pipeline; 51. Sixth pipeline; 52. Seventh pipeline. Detailed Implementation

[0015] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0016] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0017] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0018] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The illustrations only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0019] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0020] In one embodiment of the present invention, a chemical high-concentration brine treatment system is proposed, such as... Figure 1 As shown, it includes: The pre-treatment unit removes suspended solids and organic matter from the high-concentration brine, performs preliminary filtration and concentration of the high-concentration brine, and removes hardness ions from the high-concentration brine. The concentration and separation unit receives the effluent from the pretreatment unit and, for high-concentration brine: filters out water based on reverse osmosis, removes hardness ions based on sodium bed, reduces alkalinity based on decarbonation, removes COD based on activated carbon adsorption, reduces residual divalent ions based on chelate bed, and separates into Na2SO4 solution and NaCl solution based on nanofiltration. A sodium chloride solution treatment device receives NaCl solution and processes the NaCl solution by: evaporating water using an evaporator, separating solid and liquid components using a centrifuge, and drying the NaCl into granules using a vibrating fluidized bed. The sodium sulfate solution processing device receives Na2SO4 solution and processes it by: evaporating water using an evaporator, separating solids and liquids using a centrifuge, and drying the Na2SO4 into granules using a vibrating fluidized bed.

[0021] In this embodiment, to achieve low-cost, efficient, and orderly separation of salts in high-concentration brine from chemical processes, the pretreatment unit removes hardness ions from the high-concentration brine based on a weak acid sodium bed 4; the concentration and separation unit includes: The inlet of the secondary reverse osmosis unit 7 is connected to the outlet of the weak acid sodium bed 4, filtering out the water from the high concentration of brine; The decarbonation tower 9 is connected to the concentrate side of the secondary reverse osmosis unit 7 at its inlet to reduce the alkalinity of the high-concentration brine. Activated carbon tower 11, with its inlet connected to the outlet of decarbonization tower 9, removes COD from high-concentration brine; The weak acid chelate bed 13 is connected to the outlet of the decarbonation tower 9 at its inlet, which reduces the residual amount of divalent ions in high-concentration brine. The first-stage nanofiltration unit 15 is connected to the effluent from the weak acid chelate bed 13, which separates the high-concentration brine into Na2SO4 solution and NaCl solution.

[0022] In this embodiment, to improve the solution separation rate and further concentrate the sodium chloride solution, the concentration and separation device further includes: The three-stage reverse osmosis unit 17 has its inlet connected to the clear water side of the first-stage nanofiltration unit 15, and its concentrate side connected to the sodium chloride solution treatment device. The secondary nanofiltration unit 34 is connected to the concentrate side of the primary nanofiltration unit 15 at its inlet, and to the inlet of the tertiary reverse osmosis unit 17 at its clear water side. The concentrate side is also connected to the sodium sulfate solution treatment device.

[0023] In this embodiment, to achieve rapid, efficient, and low-cost granulation of NaCl in concentrated NaCl solution, the sodium chloride solution treatment device includes: The first evaporator is connected to the concentrate side of the tertiary RO system to evaporate the water in the NaCl solution. The NaCl centrifuge receives the solid-liquid phase discharge from the first evaporator and separates out moist NaCl. NaCl vibrating fluidized bed 22 receives moist NaCl, dries the moist NaCl, and outputs dried NaCl particles.

[0024] In this embodiment, to achieve rapid, efficient, and low-cost granulation of Na2SO4 in concentrated Na2SO4 solution, the sodium sulfate solution treatment device includes: The second evaporator is connected to the concentrate side of the secondary nanofiltration unit 34 to evaporate the water in the Na2SO4 solution; Na2SO4 centrifuge 38 receives the solid-liquid phase discharge of the second evaporator and separates out moist Na2SO4; Na2SO4 vibrating fluidized bed 39 receives moist Na2SO4, dries the moist Na2SO4, and outputs dried Na2SO4 particles.

[0025] In this embodiment, to further achieve complete salt recovery from the high-concentration brine, the chemical high-concentration brine treatment system also includes a mother liquor treatment device, which includes: The third evaporator receives the mother liquor separated by the NaCl centrifuge and the Na2SO4 centrifuge 38 and evaporates the mixed salt solution. A filter press receives the mixed salt solution and filters out the mixed salt.

[0026] In order to improve the output efficiency of the sodium chloride solution treatment unit, reduce the operating cost of the sodium chloride solution treatment unit, increase the NaCl recovery rate in high-concentration brine, and shorten the residence time of NaCl concentrated solution and mother liquor, the first evaporator is a two-stage evaporator. If the TDS of the centrifuged liquid in NaCl centrifuge 21 is greater than or equal to 100,000 mg / L and less than 200,000 mg / L, the centrifuged liquid is transported to the inlet of the secondary evaporator of the first evaporator. If the TDS of the centrifuged liquid from NaCl solution centrifuge 21 is less than 100,000 mg / L, the centrifuged liquid is transported to the inlet of the first-stage evaporator of the first evaporator body; If the TDS of the centrifuged liquid from NaCl solution centrifuge 21 is greater than 230,000 mg / L, the centrifuged liquid is transferred to the third evaporator.

[0027] In order to improve the output efficiency of the sodium sulfate solution treatment unit, reduce the operating cost of the sodium sulfate solution treatment unit, increase the recovery rate of Na2SO4 in high-concentration brine, and shorten the residence time of Na2SO4 concentrated solution and mother liquor, the second evaporator is a two-stage evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is greater than or equal to 130,000 mg / L and less than 230,000 mg / L, the centrifuged liquid is transported to the inlet of the secondary evaporator of the second evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is less than 130,000 mg / L, the centrifuged liquid is transported to the inlet of the first-stage evaporator of the second evaporator. If the TDS of the centrifuged liquid from the Na2SO4 solution centrifuge is greater than 250,000 mg / L, the centrifuged liquid is transferred to the third evaporator. In this embodiment, in order to improve the processing efficiency of the concentration and separation device, the front-end processing device uses an ultrafiltration unit and a front-end RO unit to initially filter and concentrate high-concentration brine. In this embodiment, in order to ensure the safety of the precision membrane, a security filter is provided at the inlet of the secondary reverse osmosis unit 7 and the secondary nanofiltration unit 34.

[0028] Further explanation like Figure 1As shown, the front-end treatment device in this embodiment includes a pretreatment unit 1, a UF+RO treatment unit 2, an RO concentrate tank 3, a weak acid sodium bed 4, and a sodium bed effluent tank 5. The pretreatment unit 1 is used to treat suspended solids and organic matter in the incoming water. The UF+RO treatment unit 2 is used for separation, extraction, purification, and concentration. The RO concentrate tank 3 is used to collect the concentrate from the RO equipment. The weak acid sodium bed 4 is used to remove hardness ions from the water. Finally, the water enters the sodium bed effluent tank 5.

[0029] The concentration and separation device in this embodiment includes a reverse osmosis security filter 6, a secondary reverse osmosis unit 7, a secondary reverse osmosis unit concentrate tank 8, a decarbonization tower 9, a decarbonization tower outlet tank 10, an activated carbon tower 11, an activated carbon tower outlet tank 12, a weak acid chelation bed 13, a chelation bed outlet tank 14, a primary nanofiltration unit 15, a nanofiltration permeate tank 16, a tertiary reverse osmosis unit 17, a tertiary reverse osmosis unit concentrate tank 18, a primary nanofiltration unit concentrate tank 32, a secondary nanofiltration unit security filter 33, a secondary nanofiltration unit 34, and a secondary nanofiltration unit concentrate tank 35. The reverse osmosis security filter 6 is connected to the secondary reverse osmosis unit 7. The secondary reverse osmosis unit concentrate tank 8 is used to receive the concentrate from the secondary reverse osmosis unit. The decarbonization tower 9 is used to reduce the alkalinity of the water. The decarbonization tower outlet tank 10 is used to receive the effluent from the decarbonization tower 9. The activated carbon tower 11 is used to remove the effluent from the incoming water. The COD in the activated carbon tower outlet tank 12 is used to receive the effluent from the activated carbon tower 11; the weak acid chelate bed 13 is used to achieve the target of divalent ion residue of less than 0.1 mg / L, the chelate bed outlet tank 14 is used to receive the chelate bed effluent, the first-stage nanofiltration unit 15 is used to separate NaCl from the Na2SO4 / NaCl mixed salt in the concentrated salt solution, the nanofiltration product water tank 16 is used to receive the NaCl solution from the product water end (clear water section) of the first-stage nanofiltration unit 15, the first-stage nanofiltration unit product water NaCl solution enters the third-stage reverse osmosis unit concentrate tank 18 after passing through the third-stage reverse osmosis unit 17; the first-stage nanofiltration unit concentrate tank 32 is connected to the second-stage nanofiltration unit security filter 33, the second-stage nanofiltration unit 34 further concentrates and separates the first-stage nanofiltration unit concentrate, and the second-stage nanofiltration unit concentrate tank 35 is used to receive the second-stage nanofiltration unit concentrate.

[0030] The sodium chloride solution treatment device in this embodiment includes a primary evaporator 19, a secondary evaporator 20, a NaCl solution centrifuge 21, a NaCl vibrating fluidized bed 22, a NaCl discharge hopper 23, a NaCl packaging machine 24, a first induced draft fan 25, a first bag filter 26, and a NaCl centrifuge filtrate tank 27. After entering the primary evaporator 19, the NaCl solution directly enters the secondary evaporator 20 and is then conveyed to the NaCl centrifuge 21 to separate the solid particles in the concentrated solution from the liquid. The separated material enters the NaCl vibrating fluidized bed 22 for drying. The NaCl product output from the NaCl vibrating fluidized bed 22 is stored in the discharge hopper. A first induced draft fan 25 is also provided between the NaCl vibrating fluidized bed 22 and the first bag filter 26. The NaCl centrifuge filtrate tank 27 is used to collect the NaCl centrifuge filtrate.

[0031] The sodium sulfate solution treatment device in this embodiment includes a three-stage evaporator 36, a four-stage evaporator 37, a Na2SO4 centrifuge 38, a Na2SO4 vibrating fluidized bed 39, a Na2SO4 discharge hopper 40, a Na2SO4 packaging machine 41, a second induced draft fan 42, a second bag filter 43, and a Na2SO4 centrifuge filtrate tank 44. The Na2SO4 solution enters the three-stage evaporator 36 and then directly enters the four-stage evaporator 37 before being conveyed to the Na2SO4 centrifuge 38 to separate the solid particles from the liquid. The separated material enters the Na2SO4 vibrating fluidized bed 39 for drying. The Na2SO4 product output from the Na2SO4 vibrating fluidized bed 39 is stored in the Na2SO4 discharge hopper 40. A second induced draft fan 42 is also installed between the Na2SO4 vibrating fluidized bed 39 and the second bag filter 43. The Na2SO4 centrifuge filtrate tank 44 is used to collect the Na2SO4 centrifuge filtrate.

[0032] The aging mother liquor treatment device includes an aging mother liquor collection tank 28, a single-stage evaporator 29, a plate and frame filter press 30, and a salt mixing hopper 31. The mother liquor from the Na2SO4 centrifuge enters the aging mother liquor collection tank 28 through the fourth pipe 48, and the mother liquor from the Na2SO4 centrifuge enters the aging mother liquor collection tank 28 through the seventh pipe 52. After the aging mother liquor is transported to the single-stage evaporator 29, it enters the plate and frame filter press 30, and the resulting mixed salt enters the salt mixing hopper 31 and is then transported out.

[0033] The concentration and separation device in this embodiment also includes a first pipe 45, which is used to transport the product of the secondary nanofiltration unit 34 to the nanofiltration product water tank 16.

[0034] The sodium chloride solution treatment device in this embodiment also includes a second pipe 46, a third pipe 47 and a fourth pipe 48. The second pipe 46 is connected to the secondary evaporator 20, the third pipe 47 is connected to the primary evaporator 19, and the fourth pipe 48 is connected to the aging mother liquor collection tank 28.

[0035] The sodium sulfate solution treatment device in this embodiment also includes a fifth pipe 50, a sixth pipe 51 and a seventh pipe 52. The fifth pipe 50 is connected to the third-stage evaporator 36, the sixth pipe 51 is connected to the fourth-stage evaporator 37, and the seventh pipe 52 is connected to the aging mother liquor collection tank 28.

[0036] The mother liquor treatment device in this embodiment includes an eighth pipe 49, which is connected to the aging mother liquor collection tank 28.

[0037] RO (reverse osmosis) membranes can filter out ions from water, resulting in virtually no ions in the product water or a significantly reduced ion content (ion filtration efficiency depends on the ion concentration at the inlet water). The clear water is pure water. However, RO membranes are expensive and have small pores that are prone to clogging. In this embodiment, particulate matter and suspended solids in high-concentration brine are first removed by sedimentation tank lining and sand filtration. Then, ultrafiltration (filtration pore size 1–100 nm) is used to remove fine particulate matter. The concentrated brine after ultrafiltration is ready for ion filtration using an RO membrane.

[0038] After ultrafiltration, the concentrated brine in this embodiment still contains a large amount of divalent hardness ions such as magnesium and calcium ions. After removing these hardness ions using the weak acid sodium bed 4, the concentrated brine contains sodium, chloride, and sulfate ions. At this point, the concentrated brine is passed into the secondary reverse osmosis unit 7 of this embodiment. The secondary reverse osmosis unit 7 can use a seawater desalination RO membrane with a larger membrane thickness and higher filtration pressure. In the secondary reverse osmosis unit 7, after reverse osmosis, a large number of water molecules in the concentrated brine are filtered out at the product water end, resulting in a significant increase in the ion concentration at the concentrate end. Because the concentrated water end of the two-stage reverse osmosis unit 7 is used, the concentrated brine also contains alkaline substances and COD (biological oxygen demand, which is commonly used in water treatment to represent the microorganisms in water). In this embodiment, these substances are removed by decarbonation tower 9 and activated carbon tower 11 respectively, and residual divalent ions such as calcium ions and magnesium ions are removed by weak acid chelate bed 13. At this time, the concentrated brine basically contains only high concentrations of sodium chloride and sodium sulfate.

[0039] In this embodiment, concentrated brine containing only sodium chloride and sodium sulfate is treated by a first-stage nanofiltration unit 15. Since the nanofiltration membrane allows sodium ions and water molecules to pass through but does not allow sulfur ions to pass through, the concentrated brine can be separated into sodium chloride solution and sodium sulfate solution. The sodium sulfate solution is produced from the concentrated water side of the first-stage nanofiltration unit 15, and the sodium chloride solution is produced from the purified water side. The concentration of the sodium sulfate solution is greater than that of the sodium chloride solution.

[0040] In this embodiment, a three-stage reverse osmosis unit 17 is set up to concentrate the sodium chloride solution produced by the first-stage nanofiltration unit 15. Based on pressure control, the concentrated sodium chloride solution is close to the crystallization concentration.

[0041] This embodiment also includes a secondary nanofiltration unit 34, which further purifies and concentrates the sodium sulfate solution produced by the primary nanofiltration unit 15. The filtered sodium chloride solution is then connected to the inlet of the tertiary reverse osmosis unit 17. The tertiary RO unit mixes this portion of the sodium chloride solution with the sodium chloride solution from the primary nanofiltration unit 15 for unified concentration. This embodiment incorporates a secondary nanofiltration unit 34, which further separates the two solutions while reducing the load on the single-stage nanofiltration.

[0042] In this embodiment, sodium chloride and sodium sulfate are separated and then fed into different evaporators for further evaporation and crystallization. The evaporators use hot gas as a heat source and are all two-stage. The crystallized solid-liquid mixture is then fed into a centrifuge for solid-liquid separation. The separated moist solid crystals are fed into a vibrating fluidized bed, which dries the crystals with minimal consumption. The purified and dried sodium chloride and sodium sulfate particles are then collected, thus completing the treatment of the high-concentration brine. This embodiment also utilizes a mother liquor treatment device to filter the centrifuged liquid (mother liquor) to obtain mixed salt. To improve the production efficiency of sodium chloride and sodium sulfate, reduce operating costs, increase recovery rate, and shorten the residence time of concentrated solutions and mother liquor, this embodiment flexibly adjusts the flow of the centrifuged liquid based on its concentration gradient, deciding whether to direct it to the primary or secondary treatment inlet of the evaporator, or directly to the filter press. When the concentration is too low, it is fed to the primary treatment inlet; when the concentration is at a medium level, it is fed to the secondary treatment inlet; and when the concentration is higher than a predetermined value, it is directly fed to the filter press to extract the mixed salt. Furthermore, the centrifuged liquid in this embodiment can be split according to the concentration range, further improving flexibility. This embodiment employs a flexible treatment method for the centrifuged liquid, which can increase the yield of pure sodium chloride and sodium sulfate while ensuring operating costs, reducing corrosion of storage containers caused by the retention of concentrated solutions or mother liquor, and thus lowering overall maintenance costs.

[0043] This embodiment adopts the above technical solution, which basically achieves zero discharge of concentrated brine wastewater and efficiently recovers sodium chloride and sodium sulfate from the concentrated brine.

[0044] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A chemical high-concentration brine treatment system, characterized in that, The system comprises: a front-stage treatment device for removing suspended solids and organic matter from the high-concentration brine, preliminarily filtering and concentrating the high-concentration brine, and removing hardness ions from the high-concentration brine; a concentration and separation device for receiving the effluent of the front-stage treatment device, and removing water from the high-concentration brine based on a reverse osmosis process, removing hardness ions based on a sodium bed, reducing alkalinity based on a decarbonization process, removing COD based on an activated carbon adsorption process, reducing divalent ion residue based on a chelate bed, and separating into a Na2SO4 solution and a NaCl solution based on a nanofiltration process; a sodium chloride solution treatment device for receiving the NaCl solution, evaporating water from the NaCl solution based on an evaporation body, separating solid and liquid based on a centrifuge, and drying NaCl into particles based on a vibrating fluidized bed; a sodium sulfate solution treatment device for receiving the Na2SO4 solution, evaporating water from the Na2SO4 solution based on an evaporation body, separating solid and liquid based on a centrifuge, and drying Na2SO4 into particles based on a vibrating fluidized bed.

2. The chemical industry high-concentration brine treatment system according to claim 1, characterized in that, The front-stage treatment device removes hardness ions from the high-concentration brine based on a weak acid sodium bed. The concentration and separation device comprises: a secondary reverse osmosis unit connected to the outlet of the weak acid sodium bed for removing water from the high-concentration brine; a decarbonization tower connected to the concentrated water side of the secondary reverse osmosis unit for reducing alkalinity of the high-concentration brine; an activated carbon tower connected to the outlet of the decarbonization tower for removing COD of the high-concentration brine; a weak acid chelate bed connected to the outlet of the decarbonization tower for reducing divalent ion residue of the high-concentration brine; a primary nanofiltration unit connected to the effluent of the weak acid chelate bed for separating the high-concentration brine into a Na2SO4 solution and a NaCl solution.

3. The chemical industry high-concentration brine treatment system according to claim 2, characterized in that, The concentration and separation device further comprises: a tertiary reverse osmosis unit connected to the clean water side of the primary nanofiltration unit, and connected to the sodium chloride solution treatment device at the concentrated water side; a secondary nanofiltration unit connected to the concentrated water side of the primary nanofiltration unit, connected to the inlet of the tertiary reverse osmosis unit at the clean water side, and connected to the sodium sulfate solution treatment device at the concentrated water side.

4. The chemical industry high-concentration brine treatment system according to claim 3, characterized in that, The sodium chloride solution treatment device comprises: a first evaporation body connected to the concentrated water side of the tertiary reverse osmosis unit for evaporating water from the NaCl solution; a NaCl centrifuge receiving the solid-liquid phase discharge of the first evaporation body for separating out moist NaCl; a NaCl vibrating fluidized bed receiving the moist NaCl for drying the moist NaCl and outputting dry NaCl particles.

5. The chemical industry high-concentration brine treatment system according to claim 4, characterized in that, The sodium sulfate solution treatment device comprises: a second evaporation body connected to the concentrated water side of the secondary nanofiltration unit for evaporating water from the Na2SO4 solution; a Na2SO4 centrifuge receiving the solid-liquid phase discharge of the second evaporation body for separating out moist Na2SO4; a Na2SO4 vibrating fluidized bed receiving the moist Na2SO4 for drying the moist Na2SO4 and outputting dry Na2SO4 particles.

6. The chemical industry high-concentration brine treatment system according to claim 5, characterized in that, The chemical high-concentration brine treatment system further comprises a mother liquor treatment device, which comprises: A third evaporation unit receives the mother liquor separated by the NaCl centrifuge and the Na2SO4 centrifuge and evaporates to separate a mixed salt solution; A filter press receives the mixed salt solution and filters out the mixed salt.

7. The chemical industry high-concentration brine treatment system according to claim 6, characterized in that, The first evaporation unit is a double-stage evaporator; If the TDS of the centrifugal liquid of the NaCl solution centrifuge is greater than or equal to 100000 mg / L and less than 200000 mg / L, the centrifugal liquid is delivered to the inlet of the second-stage evaporator of the first evaporation unit; If the TDS of the centrifugal liquid of the NaCl solution centrifuge is less than 100000 mg / L, the centrifugal liquid is delivered to the inlet of the first-stage evaporator of the first evaporation unit; If the TDS of the centrifugal liquid of the NaCl solution centrifuge is greater than 230000 mg / L, the centrifugal liquid is delivered to the third evaporation unit.

8. The chemical industry high-concentration brine treatment system according to claim 7, characterized in that, The second evaporation unit is a double-stage evaporator; If the TDS of the centrifugal liquid of the Na2SO4 solution centrifuge is greater than or equal to 130000 mg / L and less than 230000 mg / L, the centrifugal liquid is delivered to the inlet of the second-stage evaporator of the second evaporation unit; If the TDS of the centrifugal liquid of the Na2SO4 solution centrifuge is less than 130000 mg / L, the centrifugal liquid is delivered to the inlet of the first-stage evaporator of the second evaporation unit; If the TDS of the centrifugal liquid of the Na2SO4 solution centrifuge is greater than 250000 mg / L, the centrifugal liquid is delivered to the third evaporation unit.

9. The chemical industry high-concentration brine treatment system according to claim 1, characterized in that, The front-stage treatment device preliminarily filters and concentrates the high-concentration brine based on the ultrafiltration unit and the front-stage RO unit.

10. The chemical industry high-concentration brine treatment system according to claim 3, characterized in that, A security filter is arranged at the water inlet of the second-stage reverse osmosis unit and the second-stage nanofiltration unit.

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