Evaporative crystallization and salt separation treatment system for sodium sulfate and sodium chloride high-salinity wastewater

Abstract

The utility model discloses an evaporative crystallization and salt separation treatment system for sodium sulfate and sodium chloride high-salinity wastewater. The system comprises a preheating unit, a sodium sulfate evaporative crystallization unit, a sodium sulfate recovery heat exchange unit, a sodium sulfate post-treatment unit, a sodium sulfate freezing crystallization unit, a mirabilite post-treatment unit, a sodium chloride evaporative crystallization unit, a sodium chloride recovery heat exchange unit, a sodium chloride post-treatment unit and a carnallite treatment unit. According to the utility model, a sodium sulfate and sodium chloride ternary system phase diagram is combined for design optimization, high-salinity wastewater containing sodium sulfate and sodium chloride is subjected to combined treatment, the system does not produce mirabilite with low economic benefits, anhydrous sodium sulphate and anhydrous sodium chloride, the yield of carnallite can be greatly reduced, and the production cost is reduced. The treatment cost of the system is reduced; the by-product benefit of the wastewater treatment system is improved.

Description

Technical Field

[0001] This utility model belongs to the field of high-salt wastewater evaporation and salt separation treatment technology, specifically relating to a sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system. Background Technology

[0002] High-salinity wastewater generally refers to wastewater with a total salt content of more than 1%. This wastewater mainly comes from the production processes of industries such as petrochemicals, coal chemicals, mining, and power plants. After traditional water treatment, the inorganic salts in the water are gradually concentrated, thus forming a type of wastewater with high inorganic salt content, as well as high concentrations of COD and ammonia nitrogen.

[0003] Zero discharge of high-salinity wastewater involves further treating the aforementioned wastewater through pretreatment, evaporation, and crystallization processes to achieve a water recovery rate of over 95%, while simultaneously rendering the crystalline salt harmless and resource-based. Data shows that NaCl and Na₂SO₄ can account for up to 90% of the total inorganic salts in the high-salinity wastewater from these industries. Therefore, resource recovery of crystalline salt in zero discharge of high-salinity wastewater largely refers to the recovery of NaCl and Na₂SO₄. Early zero discharge methods for high-salinity wastewater only addressed miscellaneous salts; however, the disposal costs of miscellaneous salts are high. Resource-based salt separation technology for crystalline salt is the future development trend.

[0004] Currently, the main processes used for zero-discharge treatment of high-salinity wastewater are: Process 1: pretreatment + reverse osmosis + evaporation and freeze crystallization; Process 2: pretreatment + membrane treatment + nanofiltration + sodium chloride and sodium sulfate evaporation and crystallization. Process 1 aims for a total salt recovery rate of approximately 89%, while Process 2 aims for approximately 77%. Process 1 also has a shorter process flow, and most projects currently consider Process 1. However, in actual project operation, the economic benefits of the sodium sulfate produced by the freeze crystallization system of Process 1 are low, and operating costs are difficult to control. It also produces a large amount of impurities, leading to higher costs for impurity disposal.

[0005] Therefore, there is a need for a process system that produces only anhydrous sodium sulfate (sodium sulfate) and sodium chloride after the re-dissolution of Glauber's salt produced by freeze crystallization, in order to improve the total yield of the target salt and reduce the amount of impurities generated. Utility Model Content

[0006] The purpose of this invention is to provide an evaporation, crystallization, and salt separation system for high-salt wastewater containing sodium sulfate and sodium chloride, in order to solve the aforementioned problems existing in the prior art.

[0007] To achieve the above objectives, this utility model adopts the following technical solution: a system for evaporation, crystallization, and salt separation of high-salt wastewater containing sodium sulfate and sodium chloride, comprising:

[0008] The preheating unit is used to preheat high-salt wastewater containing sodium sulfate and sodium chloride.

[0009] The sodium sulfate evaporation and crystallization unit is used to treat high-salt wastewater by evaporation and crystallization to obtain a concentrated salt slurry with a solid content of 5%-15%.

[0010] The sodium sulfate recovery heat exchange unit is used to pressurize and heat the steam discharged from the sodium sulfate evaporation and crystallization unit, and then transport the pressurized and heated steam back to the sodium sulfate evaporation and crystallization unit.

[0011] The sodium sulfate post-treatment unit is used to centrifuge the concentrated salt slurry to obtain wet sodium sulfate and sodium sulfate mother liquor, and to dry the wet sodium sulfate to obtain anhydrous sodium sulfate; a sodium sulfate mother liquor reflux pipe is provided between the sodium sulfate post-treatment unit and the sodium sulfate evaporation and crystallization unit, and the sodium sulfate mother liquor reflux pipe is used to transport the sodium sulfate mother liquor to the sodium sulfate evaporation and crystallization unit.

[0012] A sodium sulfate freeze crystallization unit is used to freeze crystallize sodium sulfate mother liquor to obtain sodium sulfate slurry and supernatant mother liquor, wherein the solid content of the sodium sulfate slurry is 5%-10%.

[0013] A Glauber's salt post-treatment unit is used to centrifuge the sodium sulfate slurry to obtain wet sodium sulfate decahydrate and centrifuged clear liquid. A Glauber's salt reflux pipe is provided between the Glauber's salt post-treatment unit and the sodium sulfate evaporation and crystallization unit. The Glauber's salt reflux pipe is used to transport the saturated sodium sulfate solution produced after dissolving the wet sodium sulfate decahydrate to the sodium sulfate evaporation and crystallization unit. A centrifuged clear liquid reflux pipe is provided between the Glauber's salt post-treatment unit and the sodium sulfate freeze crystallization unit. The centrifuged clear liquid reflux pipe is used to transport the centrifuged clear liquid to the sodium sulfate freeze crystallization unit.

[0014] The sodium chloride evaporation and crystallization unit is used to evaporate and crystallize the supernatant mother liquor to obtain a sodium chloride slurry, wherein the solid content of the sodium chloride slurry is 5%-10%.

[0015] The sodium chloride recovery heat exchange unit is used to pressurize and heat the steam discharged from the sodium chloride evaporation and crystallization unit, and then transport the pressurized and heated steam back to the sodium chloride evaporation and crystallization unit.

[0016] The sodium chloride post-treatment unit is used to centrifuge the sodium chloride slurry to obtain wet sodium chloride and sodium chloride mother liquor, and to dry the wet sodium chloride to obtain dry sodium chloride. A sodium chloride mother liquor reflux pipe is provided between the sodium chloride post-treatment unit and the sodium chloride evaporation and crystallization unit, which is used to transport the sodium chloride mother liquor to the sodium chloride evaporation and crystallization unit.

[0017] The mixed salt processing unit is used to dry the sodium chloride mother liquor conveyed by the sodium chloride post-processing unit to obtain mixed salts.

[0018] As an optional implementation of the above technical solution, the preheating unit includes a feed tank, a water pump, a distilled water preheater, and a steam preheater connected in sequence. The feed tank is used to store high-salinity wastewater. The distilled water preheater has a first heat exchange chamber for inputting distilled water to preheat the high-salinity wastewater in a primary manner. The steam preheater has a second heat exchange chamber for inputting steam to preheat the high-salinity wastewater in a secondary manner.

[0019] As an optional implementation of the above technical solution, both the distilled water preheater and the steam preheater are plate heat exchangers.

[0020] As an optional embodiment of the above technical solution, the sodium sulfate evaporation and crystallization unit includes a sodium sulfate discharge pump, a sodium sulfate crystallizer separator, a sodium sulfate forced circulation evaporator, and a sodium sulfate forced circulation pump. The sodium sulfate crystallizer separator and the sodium sulfate forced circulation evaporator are connected by the sodium sulfate forced circulation pump. The sodium sulfate forced circulation pump is used to circulate the liquid in the sodium sulfate crystallizer separator, so that the liquid forms sodium sulfate crystals in the sodium sulfate forced circulation evaporator, and returns the sodium sulfate crystals to the sodium sulfate crystallizer separator to obtain a concentrated salt slurry. The steam generated by the sodium sulfate crystallizer separator is used to transport the concentrated salt slurry from the sodium sulfate crystallizer separator to the sodium sulfate post-treatment unit.

[0021] As an optional embodiment of the above technical solution, the sodium sulfate recovery heat exchange unit includes a sodium sulfate compressor, a sodium sulfate gas scrubbing tower, a condensate tank, and a condensate pump. The sodium sulfate gas scrubbing tower is used to receive the steam discharged from the sodium sulfate evaporation and crystallization unit. The sodium sulfate compressor is used to pressurize and heat the gas transported by the sodium sulfate gas scrubbing tower and transport the pressurized and heated steam to the sodium sulfate evaporation and crystallization unit. The condensate tank is used to receive the condensate discharged from the sodium sulfate evaporation and crystallization unit, and the condensate pump is used to transport the condensate from the condensate tank to the first heat exchange chamber of the distilled water preheater.

[0022] As an optional embodiment of the above technical solution, the sodium sulfate post-processing unit includes a sodium sulfate thickener, a sodium sulfate centrifuge, a sodium sulfate dryer, a sodium sulfate mother liquor tank, and a sodium sulfate mother liquor pump. The sodium sulfate thickener is connected to the sodium sulfate centrifuge, the solid output end of the sodium sulfate centrifuge is connected to the sodium sulfate dryer, and the liquid output end of the sodium sulfate centrifuge is connected to the sodium sulfate mother liquor tank. The sodium sulfate centrifuge is used to centrifuge the concentrated salt slurry to obtain wet sodium sulfate and sodium sulfate mother liquor. The sodium sulfate dryer is used to dry the wet sodium sulfate to obtain anhydrous sodium sulfate. The sodium sulfate mother liquor tank is used to store the sodium sulfate mother liquor. The input end of the sodium sulfate mother liquor pump is connected to the sodium sulfate mother liquor tank. One output end of the sodium sulfate mother liquor pump is connected to the sodium sulfate evaporation and crystallization unit through a sodium sulfate mother liquor reflux pipe, and the other output end of the sodium sulfate mother liquor pump is connected to the sodium sulfate freeze crystallization unit.

[0023] As an optional embodiment of the above technical solution, the sodium sulfate freeze crystallization unit includes a freeze crystallizer, a freeze heat exchanger, a freeze circulation pump, a sodium sulfate discharge pump, and a precooler. The freeze crystallizer and the freeze heat exchanger are connected by the freeze circulation pump. The freeze circulation pump is used to circulate the liquid in the freeze crystallizer, so that the liquid forms sodium sulfate crystals in the freeze heat exchanger, and returns the sodium sulfate crystals to the freeze crystallizer to obtain sodium sulfate slurry and supernatant mother liquor. The sodium sulfate discharge pump is used to transport the sodium sulfate slurry from the freeze crystallizer to the sodium sulfate post-processing unit. The precooler is used to preheat the supernatant mother liquor from the freeze crystallizer and transport it to the sodium chloride evaporation crystallization unit.

[0024] As an optional embodiment of the above technical solution, the Glauber's salt post-processing unit includes a Glauber's salt thickener, a Glauber's salt centrifuge, a Glauber's salt re-dissolving tank, a re-dissolving return pump, a Glauber's salt mother liquor tank, and a Glauber's salt mother liquor pump. The Glauber's salt thickener is connected to the Glauber's salt centrifuge. The solid output end of the Glauber's salt centrifuge is connected to the Glauber's salt re-dissolving tank, and the liquid output end of the Glauber's salt centrifuge is connected to the Glauber's salt mother liquor tank. The Glauber's salt centrifuge is used to centrifuge the sodium sulfate slurry to obtain wet sodium sulfate decahydrate and centrifuged clear liquid. The Glauber's salt re-dissolving tank is used to dissolve the wet sodium sulfate decahydrate to obtain a saturated sodium sulfate solution. The re-dissolving return pump is used to transport the saturated sodium sulfate solution to the sodium sulfate evaporation and crystallization unit through the Glauber's salt reflux pipe. The Glauber's salt mother liquor tank is used to store the centrifuged clear liquid, and the Glauber's salt mother liquor pump is used to transport the centrifuged clear liquid to the sodium sulfate freeze crystallization unit through the centrifuged clear liquid reflux pipe.

[0025] As an optional embodiment of the above technical solution, the sodium chloride evaporation and crystallization unit includes a sodium chloride crystallization separator, a sodium chloride forced circulation evaporator, a sodium chloride forced circulation pump, and a sodium chloride discharge pump. The sodium chloride crystallization separator and the sodium chloride forced circulation evaporator are connected by the sodium chloride forced circulation pump. The sodium chloride forced circulation pump is used to circulate the liquid in the sodium chloride crystallization separator, so that the liquid forms sodium chloride crystals in the sodium chloride forced circulation evaporator, and returns the sodium chloride crystals to the sodium chloride crystallization separator to obtain a sodium chloride slurry. The steam generated by the sodium chloride crystallization separator is used to transport the sodium chloride recovery heat exchange unit, and the sodium chloride discharge pump is used to transport the sodium chloride slurry from the sodium chloride crystallization separator to the sodium chloride post-treatment unit.

[0026] As an optional implementation of the above technical solution, the sodium chloride recovery heat exchange unit includes a sodium chloride compressor and a sodium chloride scrubbing tower. The sodium chloride scrubbing tower is used to receive the steam discharged from the sodium chloride evaporation and crystallization unit. The sodium chloride compressor is used to pressurize and heat the gas conveyed by the sodium chloride scrubbing tower and convey the pressurized and heated steam to the sodium chloride evaporation and crystallization unit.

[0027] As an optional embodiment of the above technical solution, the sodium chloride post-treatment unit includes a sodium chloride thickener, a sodium chloride centrifuge, a sodium chloride dryer, a sodium chloride mother liquor tank, and a sodium chloride mother liquor pump. The sodium chloride thickener is connected to the sodium chloride centrifuge, the solid output end of the sodium chloride centrifuge is connected to the sodium chloride dryer, and the liquid output end of the sodium chloride centrifuge is connected to the sodium chloride mother liquor tank. The sodium chloride centrifuge is used to centrifuge the sodium chloride slurry to obtain wet sodium chloride and sodium chloride mother liquor. The sodium chloride dryer is used to dry the wet sodium chloride to obtain dry sodium chloride. The sodium chloride mother liquor tank is used to store the sodium chloride mother liquor. The input end of the sodium chloride mother liquor pump is connected to the sodium chloride mother liquor tank, one output end of the sodium chloride mother liquor pump is connected to the sodium chloride evaporation and crystallization unit through a sodium chloride mother liquor reflux pipe, and the other output end of the sodium chloride mother liquor pump is connected to the mixed salt treatment unit.

[0028] As an optional embodiment of the above technical solution, the mixed salt processing unit includes a mother liquor dryer, which is a scraper drum dryer or a rake dryer. The mother liquor dryer is used to dry the sodium chloride mother liquor and output mixed salt.

[0029] The beneficial effects of this utility model are as follows:

[0030] This invention optimizes the design by combining the phase diagram of the sodium sulfate and sodium chloride ternary system, and combines the treatment of high-salt wastewater containing sodium sulfate and sodium chloride. The system does not produce sodium sulfate, which has low economic benefits, but produces sodium sulfate and anhydrous sodium chloride. It can also significantly reduce the output of miscellaneous salts, reduce the system's treatment cost, and improve the by-product benefits of the wastewater treatment system. Attached Figure Description

[0031] Figure 1 This is a flowchart of a high-salt wastewater evaporation, crystallization, and salt separation treatment system for sodium sulfate and sodium chloride in one embodiment of this utility model;

[0032] Figure 2 This is a schematic diagram showing the connection of the preheating unit, sodium sulfate evaporation and crystallization unit, sodium sulfate recovery and heat exchange unit, sodium sulfate post-treatment unit, sodium sulfate freeze crystallization unit and mirabilite post-treatment unit in one embodiment of this utility model.

[0033] Figure 3 This is a schematic diagram showing the connection of the sodium chloride evaporation and crystallization unit, the sodium chloride recovery and heat exchange unit, the sodium chloride post-treatment unit, and the miscellaneous salt treatment unit in one embodiment of this utility model.

[0034] In the diagram: 1-Preheating unit; 2-Sodium sulfate evaporation and crystallization unit; 3-Sodium sulfate recovery and heat exchange unit; 4-Sodium sulfate post-treatment unit; 5-Sodium sulfate freeze crystallization unit; 6-Sodium sulfate post-treatment unit; 7-Sodium chloride evaporation and crystallization unit; 8-Sodium chloride recovery and heat exchange unit; 9-Sodium chloride post-treatment unit; 10-Miscellaneous salt treatment unit;

[0035] 11-Feed box; 12-Water pump; 13-Distilled water preheater; 14-Steam preheater;

[0036] 21-Sodium sulfate discharge pump; 22-Sodium sulfate crystallizer separator; 23-Sodium sulfate forced circulation evaporator; 24-Sodium sulfate forced circulation pump; 231-Cold side inlet of sodium sulfate forced circulation evaporator; 232-Cold side outlet of sodium sulfate forced circulation evaporator;

[0037] 31-Sodium sulfate compressor; 32-Sodium sulfate scrubbing tower; 33-Condensate tank; 34-Condensate pump;

[0038] 41-Sodium sulfate thickener; 42-Sodium sulfate centrifuge; 43-Sodium sulfate dryer; 44-Sodium sulfate mother liquor tank; 45-Sodium sulfate mother liquor pump;

[0039] 51-Freezing crystallizer; 52-Freezing heat exchanger; 53-Freezing circulation pump; 54-Sodium sulfate discharge pump; 55-Precooler;

[0040] 61-Sodium sulfate thickener; 62-Sodium sulfate centrifuge; 63-Sodium sulfate remelting tank; 64-Remelting return pump; 65-Sodium sulfate mother liquor tank; 66-Sodium sulfate mother liquor pump;

[0041] 71 - Sodium chloride crystallizer separator; 72 - Sodium chloride forced circulation evaporator; 73 - Sodium chloride forced circulation pump; 74 - Sodium chloride discharge pump; 721 - Cold side inlet of sodium chloride forced circulation evaporator; 722 - Cold side outlet of sodium chloride forced circulation evaporator;

[0042] 81-Sodium chloride compressor; 82-Sodium chloride scrubbing tower;

[0043] 91 - Sodium chloride thickener; 92 - Sodium chloride centrifuge; 93 - Sodium chloride dryer; 94 - Sodium chloride mother liquor tank; 95 - Sodium chloride mother liquor pump;

[0044] 101-Mother liquor dryer. Detailed Implementation

[0045] like Figures 1-3 As shown, this utility model provides an evaporation crystallization and salt separation treatment system for high-salt wastewater containing sodium sulfate and sodium chloride, which includes: a preheating unit 1, a sodium sulfate evaporation crystallization unit 2, a sodium sulfate recovery heat exchange unit 3, a sodium sulfate post-treatment unit 4, a sodium sulfate freezing crystallization unit 5, a mirabilite post-treatment unit 6, a sodium chloride evaporation crystallization unit 7, a sodium chloride recovery heat exchange unit 8, a sodium chloride post-treatment unit 9, and a miscellaneous salt treatment unit 10.

[0046] The preheating unit, connected in sequence, consists of a feed tank 11, a water pump 12, a distilled water preheater 13, and a steam preheater 14. High-salt wastewater containing sodium sulfate and sodium chloride enters the feed tank 11 as raw water and is then pumped by the water pump 12 into the distilled water preheater 13 and the steam preheater 14. Both the distilled water preheater 13 and the steam preheater 14 are plate heat exchangers. The distilled water preheater 13 has a first heat exchange chamber for inputting distilled water to preheat the high-salt wastewater initially. The steam preheater 14 has a second heat exchange chamber for inputting steam to preheat the high-salt wastewater a second time. The raw water is generally preheated to 90-100°C in the end.

[0047] The sodium sulfate evaporation and crystallization unit 2 includes a sodium sulfate discharge pump 21, a sodium sulfate crystallization separator 22, a sodium sulfate forced circulation evaporator 23, and a sodium sulfate forced circulation pump 24. Preheated raw water enters the sodium sulfate crystallization separator 22 and circulates and exchanges heat in the forced circulation evaporator 23 via the forced circulation pump 24. After heating, it returns to the crystallization separator 22 for flash evaporation and crystallization of sodium sulfate, yielding a concentrated salt slurry. The forced circulation evaporator 23 is a shell-and-tube heat exchanger with two interfaces: a hot side and a cold side. The hot side receives compressor outlet steam or live steam, while the cold side receives circulating liquid. The hot side medium is high-temperature steam, which heats the heat exchange tubes of the forced circulation evaporator to transfer heat for heating the cold side circulating liquid. The hot side steam temperature is 106~108℃, and the cold side circulating liquid temperature is 98~100℃. In this example, the sodium sulfate forced circulation pump 24 is an axial flow pump with a designed head of 2.8~4m and an outlet pressure of 0.25~0.32MPa. The outlet of the sodium sulfate forced circulation pump 24 is connected to the cold side inlet 231 of the sodium sulfate forced circulation evaporator. After heat exchange, it returns to the forced circulation crystallizer 22 for flash crystallization via the cold side outlet 232 of the sodium sulfate forced circulation evaporator. The secondary steam generated at the top of the forced circulation crystallizer 22 enters the sodium sulfate scrubbing tower 32 in the sodium sulfate recovery heat exchange unit 3. The concentrated salt slurry (solid content 5%~10%) at the bottom of the sodium sulfate crystallizer 22 is transported to the post-sodium sulfate post-treatment unit 4 via the sodium sulfate discharge pump 21.

[0048] The sodium sulfate recovery heat exchange unit 3 includes a sodium sulfate compressor 31, a sodium sulfate scrubbing tower 32, a condensate tank 33, and a condensate pump 34. The sodium sulfate compressor 31 is a centrifugal steam compressor that pressurizes and heats the secondary steam generated by the sodium sulfate crystallizer 22, returning it to the sodium sulfate forced circulation evaporator 23 as a heat source for evaporation, concentration, and crystallization of the circulating liquid. The secondary steam generated by the sodium sulfate crystallizer 22 enters the sodium sulfate compressor 31 after being defoamed by the scrubbing tower 32. The sodium sulfate compressor 31 raises the temperature of the secondary steam by 16-18°C. The secondary steam exiting the sodium sulfate compressor 31 returns to the sodium sulfate forced circulation evaporator 23 for heat exchange and condensation, then enters the condensate tank 33. The condensate is then pumped by the condensate pump 34 to the first heat exchange chamber of the distilled water preheater 13 to exchange heat with the raw water. After the condensate temperature drops to 50-60°C, it is discharged outside the system. If an even lower condensate temperature is required, a condensate cooling plate heat exchanger can be added to further reduce the condensate temperature to below 45°C.

[0049] The sodium sulfate post-processing unit 4 includes a sodium sulfate thickener 41, a sodium sulfate centrifuge 42, a sodium sulfate dryer 43, a sodium sulfate mother liquor tank 44, and a sodium sulfate mother liquor pump 45. The sodium sulfate thickener 41 is connected to the sodium sulfate centrifuge 42, the solid output end of the sodium sulfate centrifuge 42 is connected to the sodium sulfate dryer 43, and the liquid output end of the sodium sulfate centrifuge 42 is connected to the sodium sulfate mother liquor tank 44. The sodium sulfate thickener 41 is equipped with a stirrer to increase the solid-liquid ratio of the concentrated salt slurry, which is then discharged to the sodium sulfate centrifuge 42. The sodium sulfate centrifuge 42 centrifuges the concentrated salt slurry to obtain wet sodium sulfate and sodium sulfate mother liquor. The water content of the wet sodium sulfate is 3%~5%. The centrifuged wet sodium sulfate enters the sodium sulfate dryer 43 for drying and dehydration until the water content is less than 0.5%, resulting in anhydrous sodium sulfate. Sodium sulfate mother liquor tank 44 is used to store sodium sulfate mother liquor. The input end of the sodium sulfate mother liquor pump 45 is connected to the sodium sulfate mother liquor tank 44. One output end of the sodium sulfate mother liquor pump 45 is connected to the sodium sulfate evaporation and crystallization unit 2 through the sodium sulfate mother liquor return pipe, and the other output end of the sodium sulfate mother liquor pump 45 is connected to the sodium sulfate freeze crystallization unit 5. When the sodium chloride content in the sodium sulfate mother liquor rises to a set concentration, the sodium sulfate mother liquor pump 45 transports the sodium sulfate mother liquor to the precooler 55 in the sodium sulfate freeze crystallization unit 5 for preliminary cooling.

[0050] The sodium sulfate cryogenic crystallization unit 5 includes a cryogenic crystallizer 51, a cryogenic heat exchanger 52, a cryogenic circulation pump 53, a sodium sulfate discharge pump 54, and a precooler 55. The sodium sulfate mother liquor pump 45 transports the high-temperature sodium sulfate mother liquor to the precooler 55 for heat exchange and cooling, and then to the cryogenic crystallizer 51. In this example, the cryogenic circulation pump 53 is an axial flow pump with a head of 2.5~3.5m. It draws the circulating liquid from the cryogenic crystallizer 51, cools it through the cryogenic heat exchanger 52, and then returns it to the cryogenic crystallizer 51 for further cooling. The cryogenic heat exchanger 52 is a shell-and-tube heat exchanger with circulating liquid on the hot side and chilled water on the cold side. The chilled water is recycled and ultimately cools the circulating liquid to -5℃ to produce sodium sulfate decahydrate crystals. Finally, sodium sulfate slurry is obtained at the bottom of the cryogenic crystallizer 51, and supernatant mother liquor is obtained at the top. Sodium sulfate slurry (5%~10% solids content) is transported to sodium sulfate post-treatment unit 6 via sodium sulfate discharge pump 54. The supernatant mother liquor is preheated by post-cooler 55 and then transported to sodium chloride evaporation and crystallization unit 7 after the temperature rises to 50~60℃.

[0051] The Glauber's salt post-processing unit 6 includes a Glauber's salt thickener 61, a Glauber's salt centrifuge 62, a Glauber's salt re-dissolving tank 63, a re-dissolving return pump 64, a Glauber's salt mother liquor tank 65, and a Glauber's salt mother liquor pump 66. The Glauber's salt thickener 61 is connected to the Glauber's salt centrifuge 62. The solid output end of the Glauber's salt centrifuge 62 is connected to the Glauber's salt re-dissolving tank 63, and the liquid output end of the Glauber's salt centrifuge 62 is connected to the Glauber's salt mother liquor tank 65. The Glauber's salt thickener 61 is equipped with a stirrer to increase the solid-liquid ratio of the sodium sulfate slurry. The slurry is then discharged to the Glauber's salt centrifuge 62, which centrifuges the sodium sulfate slurry to obtain wet sodium sulfate decahydrate and centrifuged clear liquid. The wet sodium sulfate decahydrate has a water content of 3% to 5%. The centrifuged wet sodium sulfate decahydrate falls into the Glauber's salt remelting tank 63. The high-temperature condensate generated by evaporation and condensation is transported to the Glauber's salt remelting tank 63. Depending on the actual situation, a steam coil can be used for heating. The sodium sulfate decahydrate dissolves in the Glauber's salt remelting tank 63 to produce a saturated sodium sulfate solution. The solution is then transported back to the sodium sulfate crystallizer 22 in the sodium sulfate evaporation and crystallization unit 2 via the remelting return pump 64 to evaporate anhydrous sodium sulfate. The centrifuged clear liquid enters the Glauber's salt mother liquor tank 65, and a portion of it is transported back to the freeze crystallizer 51 in the sodium sulfate freeze crystallization unit 5 via the Glauber's salt mother liquor pump 66. The sodium sulfate content in the supernatant mother liquor is reduced through circulating cooling crystallization. When the sodium sulfate content in the supernatant mother liquor drops to about 0.6%, it is transported to the precooler 55 and heated to 50~60℃ before entering the sodium chloride evaporation crystallization unit 7.

[0052] The sodium chloride evaporation and crystallization unit 7 includes a sodium chloride forced circulation evaporator 72, a sodium chloride crystallization separator 71, a sodium chloride forced circulation pump 73, and a sodium chloride discharge pump 74. The supernatant mother liquor, preheated by the precooler 55, enters the sodium chloride crystallization separator 71 and circulates and exchanges heat in the sodium chloride forced circulation evaporator 72 via the sodium chloride forced circulation pump 73. After being heated, it returns to the sodium chloride crystallization separator 71 for flash evaporation and sodium chloride crystallization. The sodium chloride forced circulation evaporator 72 is a shell-and-tube heat exchanger with two interfaces: a hot side and a cold side. The hot side receives compressor outlet steam or live steam, while the cold side receives the circulating mother liquor. The hot side medium is high-temperature steam, which heats the heat exchange tubes of the forced circulation evaporator to transfer heat for heating the cold side circulating liquid. The hot side steam temperature is 108~110℃, and the cold side circulating liquid temperature is 98~100℃. In this example, the sodium chloride forced circulation pump 73 is an axial flow pump with a design head of 2.8~4m and an outlet pressure of 0.25~0.32MPa. The outlet of the sodium chloride forced circulation pump 73 is connected to the cold side inlet 721 of the sodium chloride forced circulation evaporator. After heat exchange, it returns to the sodium chloride crystallizer 71 for flash crystallization via the cold side outlet 722 of the sodium chloride forced circulation evaporator. The secondary steam generated at the top of the sodium chloride crystallizer 71 enters the sodium chloride scrubbing tower 82 in the sodium chloride recovery heat exchange unit 8. The sodium chloride slurry (solid content 5%~10%) at the bottom of the crystallizer 71 is transported to the post-sodium chloride post-treatment unit 9 via the sodium chloride discharge pump 74.

[0053] The sodium chloride recovery heat exchange unit 8 includes a sodium chloride compressor 81 and a sodium chloride scrubbing tower 82. The sodium sulfate compressor 81 is a centrifugal steam compressor, which pressurizes and heats the secondary steam generated by the sodium chloride crystallizer 71 and returns it to the sodium chloride forced circulation evaporator 72 as a heat source for evaporation, concentration, and crystallization of the circulating liquid. The secondary steam generated by the sodium chloride crystallizer 71 enters the sodium chloride compressor 81 after being defoamed by the sodium chloride scrubbing tower 82. The sodium chloride compressor 81 raises the temperature of the secondary steam by 18~20℃. The secondary steam at the outlet of the sodium chloride compressor 81 returns to the sodium chloride forced circulation evaporator 72 for heat exchange and condensation, and then enters the condensate tank 33. It is then pumped by the condensate pump 34 to the first heat exchange chamber of the distilled water preheater 13 to exchange heat with the raw water.

[0054] The sodium chloride post-processing unit 9 includes a sodium chloride thickener 91, a sodium chloride centrifuge 92, a sodium chloride dryer 93, a sodium chloride mother liquor tank 94, and a sodium chloride mother liquor pump 95. The sodium chloride thickener 91 is connected to the sodium chloride centrifuge 92, the solid output end of which is connected to the sodium chloride dryer 93, and the liquid output end of which is connected to the sodium chloride mother liquor tank 94. The sodium chloride thickener 91 is equipped with a stirrer to increase the solid-liquid ratio of the sodium chloride slurry. The slurry is then discharged to the sodium chloride centrifuge 92, which centrifuges the slurry to obtain wet sodium chloride and sodium chloride mother liquor. The wet sodium chloride has a moisture content of 3%–5%. The centrifuged wet sodium chloride enters the sodium chloride dryer 93 for drying and dehydration until the moisture content is less than 0.5%, yielding dry sodium chloride. After centrifugation, the sodium chloride mother liquor enters the sodium chloride mother liquor tank 94. When the sodium sulfate content in the sodium chloride mother liquor rises to the set concentration, the sodium chloride mother liquor pump 95 transports the sodium chloride mother liquor in the mother liquor tank 94 to the miscellaneous salt treatment unit 10.

[0055] The mixed salt processing unit 10 includes a mother liquor dryer 101; the mother liquor dryer 101 is a scraper drum dryer or a rake dryer, and the sodium chloride mother liquor enters the mother liquor dryer 101 for drying treatment and then outputs mixed salt.

[0056] This invention provides a system for the evaporation, crystallization, and salt separation of high-salt wastewater containing sodium sulfate and sodium chloride. The mixed liquid, used as raw water, is preheated to 90-100°C via a distillation water preheater 13 and a steam preheater 14. The preheated raw water then enters a sodium sulfate forced circulation evaporator 23, where it is concentrated at 90°C. The resulting sodium sulfate crystals are pumped to a sodium sulfate thickener 41 via a sodium sulfate discharge pump. After passing through a sodium sulfate centrifuge 42, wet sodium sulfate is obtained. This wet salt is then dried in a dryer 43 to obtain sodium sulfate dry salt. The centrifuged sodium sulfate mother liquor is pumped back to the sodium sulfate crystallizer 22 via a sodium sulfate mother liquor pump 45. When the sodium chloride concentration in the mother liquor reaches the designed value, the mother liquor is pumped to a sodium sulfate freeze crystallizer 51 via the sodium sulfate mother liquor pump 45. The sodium sulfate decahydrate slurry produced by freeze crystallization is pumped to a sodium sulfate thickener 51 via a sodium sulfate discharge pump 54. After passing through the Glauber's salt centrifuge 62, wet sodium sulfate decahydrate is obtained. High-temperature condensate is added to redissolve the wet sodium sulfate decahydrate and then returned to the hot crystallization unit to produce anhydrous sodium sulfate. When the sodium sulfate content in the mother liquor of the Glauber's salt centrifuge 62 decreases and rises to the design concentration, the Glauber's salt mother liquor pump 66 transports the supernatant mother liquor to the sodium chloride evaporation and crystallization unit 7 to produce sodium chloride crystallized salt. The crystallized salt is then transported to the sodium chloride thickener 91 by the sodium chloride discharge pump 74. After passing through the sodium chloride centrifuge 92, wet sodium chloride is obtained. The wet sodium chloride is then dried by the dryer 93 to obtain dry sodium chloride. The centrifuged sodium chloride mother liquor is returned to the sodium chloride crystallization separator 71 by the sodium chloride mother liquor pump 95. When the sodium sulfate concentration in the mother liquor reaches the design value, the mother liquor is transported to the mixed salt treatment unit by the sodium chloride mother liquor pump 95. After being processed by the mother liquor dryer 101 in the mixed salt treatment unit, mixed salt is obtained.

[0057] This invention optimizes the design by combining the phase diagram of the sodium sulfate and sodium chloride ternary system, and combines the treatment of high-salt wastewater containing sodium sulfate and sodium chloride. The system does not produce sodium sulfate, which has low economic benefits, but produces sodium sulfate and anhydrous sodium chloride. It can also significantly reduce the output of miscellaneous salts, reduce the system's treatment cost, and improve the by-product benefits of the wastewater treatment system.

[0058] The workflow of the above-mentioned high-salt wastewater evaporation, crystallization, and salt separation treatment system for sodium sulfate and sodium chloride includes the following steps:

[0059] (1) Preheat the high-salt wastewater containing sodium sulfate and sodium chloride to 90~100℃.

[0060] (2) The evaporation temperature of sodium sulfate evaporation crystallization unit 2 is set to 90℃. The secondary steam enters the sodium sulfate steam compressor after being defoamed by the gas scrubbing tower. The sodium sulfate crystals produced by evaporation crystallization are dehydrated by a centrifuge and have a water content of <5%. After being dried by sodium sulfate dryer 43, sodium sulfate with a water content of <0.5% is produced.

[0061] (3) The sodium sulfate mother liquor temperature is 95~100℃. The sodium sulfate mother liquor first passes through the precooler 55 to exchange heat with the frozen mother liquor. After the temperature drops to 50~60℃, it enters the sodium sulfate freeze crystallization unit 5. The sodium sulfate freeze crystallization unit 5 cools the sodium sulfate mother liquor to about -5℃ through chilled water. Centrifugation produces sodium sulfate decahydrate (sodium sulfate). Sodium sulfate is dissolved in high-temperature condensate water and then returned to the sodium sulfate evaporation crystallization unit 2 to produce sodium sulfate. The frozen mother liquor passes through the precooler 55 to exchange heat with the high-temperature mother liquor and is then heated to 50~60℃ before going to the sodium chloride evaporation crystallization system. The frozen mother liquor mainly contains sodium chloride (25%) and contains a very small amount of sodium sulfate (about 0.6%).

[0062] (4) After being preheated, the frozen mother liquor enters the sodium chloride evaporation and crystallization unit 7, where the evaporation temperature is 90°C. The secondary steam is defoamed by the gas scrubbing tower and then enters the sodium chloride steam compressor. The sodium chloride crystals produced by evaporation and crystallization are dehydrated by a centrifuge and have a water content of <5%. After being dried by the sodium chloride dryer 93, sodium chloride with a water content of <0.5% is produced.

[0063] (5) As sodium chloride evaporates and crystallizes continuously, the content of impurities such as sodium sulfate and organic matter in the system increases. The mother liquor of sodium chloride is centrifuged and discharged to the mother liquor dryer 101. The mother liquor dryer 101 is a scraper drum dryer or a rake dryer. After the mother liquor enters the dryer, it will be mixed salt (mixed salt).

[0064] Compared with existing technologies, this invention optimizes the system so that the sodium sulfate produced by freeze crystallization is returned to hot crystallization. The system produces sodium sulfate, sodium chloride and a small amount of miscellaneous salts. The total yield of the target salt can reach 91%, and the miscellaneous salt rate can be reduced to below 7%, which improves the economic efficiency of the system and reduces the cost of miscellaneous salt disposal.

[0065] In this description of the utility model, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. They can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model. Furthermore, the specific features and structures described in the embodiments are included in at least one implementation method. Those skilled in the art can combine features from different implementation methods without contradiction. The scope of protection of this utility model is not limited to the specific implementation methods described above. Based on the basic technical concept of this utility model, implementation methods that can be conceived by those skilled in the art without creative effort are all within the scope of protection of this utility model.

Claims

1. A system for evaporation, crystallization, and salt separation of high-salt wastewater containing sodium sulfate and sodium chloride, characterized in that, include: The preheating unit (1) is used to preheat high-salt wastewater containing sodium sulfate and sodium chloride; Sodium sulfate evaporation and crystallization unit (2) is used to treat high-salt wastewater by evaporation and crystallization to obtain concentrated salt slurry, wherein the solid content of the concentrated salt slurry is 5%-15%; The sodium sulfate recovery heat exchange unit (3) is used to pressurize and heat the steam discharged from the sodium sulfate evaporation and crystallization unit (2), and to transport the pressurized and heated steam to the sodium sulfate evaporation and crystallization unit (2). The sodium sulfate post-treatment unit (4) is used to centrifuge the concentrated salt slurry to obtain wet sodium sulfate and sodium sulfate mother liquor, and to dry the wet sodium sulfate to obtain anhydrous sodium sulfate; a sodium sulfate mother liquor reflux pipe is provided between the sodium sulfate post-treatment unit (4) and the sodium sulfate evaporation and crystallization unit (2), and the sodium sulfate mother liquor reflux pipe is used to transport the sodium sulfate mother liquor to the sodium sulfate evaporation and crystallization unit (2); Sodium sulfate freeze crystallization unit (5) is used to freeze crystallize sodium sulfate mother liquor to obtain sodium sulfate slurry and supernatant mother liquor, wherein the solid content of the sodium sulfate slurry is 5%-10%; The Glauber's salt post-treatment unit (6) is used to centrifuge the sodium sulfate slurry to obtain wet sodium sulfate decahydrate and centrifuged clear liquid; a Glauber's salt reflux pipe is provided between the Glauber's salt post-treatment unit (6) and the sodium sulfate evaporation and crystallization unit (2), and the Glauber's salt reflux pipe is used to transport the saturated sodium sulfate solution generated after dissolving the wet sodium sulfate decahydrate to the sodium sulfate evaporation and crystallization unit (2); a centrifuged clear liquid reflux pipe is provided between the Glauber's salt post-treatment unit (6) and the sodium sulfate freeze crystallization unit (5), and the centrifuged clear liquid reflux pipe is used to transport the centrifuged clear liquid to the sodium sulfate freeze crystallization unit (5); The sodium chloride evaporation and crystallization unit (7) is used to evaporate and crystallize the supernatant mother liquor to obtain a sodium chloride slurry, wherein the solid content of the sodium chloride slurry is 5%-10%. Sodium chloride recovery heat exchange unit (8) is used to pressurize and heat the steam discharged from sodium chloride evaporation and crystallization unit (7), and to transport the pressurized and heated steam to sodium chloride evaporation and crystallization unit (7); The sodium chloride post-treatment unit (9) is used to centrifuge the sodium chloride slurry to obtain wet sodium chloride and sodium chloride mother liquor, and to dry the wet sodium chloride to obtain dry sodium chloride; a sodium chloride mother liquor reflux pipe is provided between the sodium chloride post-treatment unit (9) and the sodium chloride evaporation and crystallization unit (7), and the sodium chloride mother liquor reflux pipe is used to transport the sodium chloride mother liquor to the sodium chloride evaporation and crystallization unit (7); The miscellaneous salt processing unit (10) is used to dry the sodium chloride mother liquor conveyed by the sodium chloride post-processing unit (9) to obtain miscellaneous salt.

2. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The preheating unit includes a feed box (11), a water pump (12), a distilled water preheater (13), and a steam preheater (14) connected in sequence. The feed box (11) is used to store high-salt wastewater. The distilled water preheater (13) has a first heat exchange chamber for inputting distilled water to preheat the high-salt wastewater. The steam preheater (14) has a second heat exchange chamber for inputting steam to preheat the high-salt wastewater. Both the distilled water preheater (13) and the steam preheater (14) are plate heat exchangers.

3. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium sulfate evaporation and crystallization unit (2) includes a sodium sulfate discharge pump (21), a sodium sulfate crystallizer (22), a sodium sulfate forced circulation evaporator (23), and a sodium sulfate forced circulation pump (24). The sodium sulfate crystallizer (22) and the sodium sulfate forced circulation evaporator (23) are connected by the sodium sulfate forced circulation pump (24). The sodium sulfate forced circulation pump (24) is used to circulate the liquid in the sodium sulfate crystallizer (22), so that the liquid forms sodium sulfate crystals in the sodium sulfate forced circulation evaporator (23), and returns the sodium sulfate crystals to the sodium sulfate crystallizer (22) to obtain a concentrated salt slurry. The steam generated by the sodium sulfate crystallizer (22) is used to transport the sodium sulfate recovery heat exchange unit (3). The sodium sulfate discharge pump (21) is used to transport the concentrated salt slurry from the sodium sulfate crystallizer (22) to the sodium sulfate post-treatment unit (4).

4. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 2, characterized in that, The sodium sulfate recovery heat exchange unit (3) includes a sodium sulfate compressor (31), a sodium sulfate gas scrubbing tower (32), a condensate tank (33), and a condensate pump (34). The sodium sulfate gas scrubbing tower (32) is used to receive the steam discharged from the sodium sulfate evaporation and crystallization unit (2). The sodium sulfate compressor (31) is used to pressurize and heat the gas transported by the sodium sulfate gas scrubbing tower (32) and transport the pressurized and heated steam to the sodium sulfate evaporation and crystallization unit (2). The condensate tank (33) is used to receive the condensate discharged from the sodium sulfate evaporation and crystallization unit (2). The condensate pump (34) is used to transport the condensate from the condensate tank (33) to the first heat exchange chamber of the distilled water preheater (13).

5. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium sulfate post-processing unit (4) includes a sodium sulfate thickener (41), a sodium sulfate centrifuge (42), a sodium sulfate dryer (43), a sodium sulfate mother liquor tank (44), and a sodium sulfate mother liquor pump (45). The sodium sulfate thickener (41) is connected to the sodium sulfate centrifuge (42), the solid output end of the sodium sulfate centrifuge (42) is connected to the sodium sulfate dryer (43), and the liquid output end of the sodium sulfate centrifuge (42) is connected to the sodium sulfate mother liquor tank (44). The sodium sulfate centrifuge (42) is used to centrifuge the concentrated salt slurry. The sodium sulfate wet salt and sodium sulfate mother liquor are obtained by processing the sodium sulfate wet salt. The sodium sulfate dryer (43) is used to dry the sodium sulfate wet salt and obtain anhydrous sodium sulfate. The sodium sulfate mother liquor tank (44) is used to store the sodium sulfate mother liquor. The input end of the sodium sulfate mother liquor pump (45) is connected to the sodium sulfate mother liquor tank (44). One output end of the sodium sulfate mother liquor pump (45) is connected to the sodium sulfate evaporation crystallization unit (2) through the sodium sulfate mother liquor reflux pipe. The other output end of the sodium sulfate mother liquor pump (45) is connected to the sodium sulfate freeze crystallization unit (5).

6. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium sulfate freeze crystallization unit (5) includes a freeze crystallizer (51), a freeze heat exchanger (52), a freeze circulation pump (53), a sodium sulfate discharge pump (54), and a precooler (55). The freeze crystallizer (51) and the freeze heat exchanger (52) are connected by the freeze circulation pump (53). The freeze circulation pump (53) is used to circulate the liquid in the freeze crystallizer (51), so that the liquid forms sodium sulfate crystals in the freeze heat exchanger (52) and returns the sodium sulfate crystals to the freeze crystallizer (51) to obtain sodium sulfate slurry and supernatant mother liquor. The sodium sulfate discharge pump (54) is used to transport the sodium sulfate slurry from the freeze crystallizer (51) to the sodium sulfate post-processing unit (6). The precooler (55) is used to preheat the supernatant mother liquor from the freeze crystallizer (51) and transport it to the sodium chloride evaporation crystallization unit (7).

7. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The Glauber's salt post-processing unit (6) includes a Glauber's salt thickener (61), a Glauber's salt centrifuge (62), a Glauber's salt re-dissolving tank (63), a re-dissolving return pump (64), a Glauber's salt mother liquor tank (65), and a Glauber's salt mother liquor pump (66). The Glauber's salt thickener (61) is connected to the Glauber's salt centrifuge (62). The solid output end of the Glauber's salt centrifuge (62) is connected to the Glauber's salt re-dissolving tank (63), and the liquid output end of the Glauber's salt centrifuge (62) is connected to the Glauber's salt mother liquor tank (65). The Glauber's salt centrifuge (62) is used to process... The sodium sulfate slurry is centrifuged to obtain wet sodium sulfate decahydrate and centrifuged clear liquid. The Glauber's salt re-dissolving tank (63) is used to dissolve the wet sodium sulfate decahydrate to obtain a saturated sodium sulfate solution. The re-dissolving return pump (64) is used to transport the saturated sodium sulfate solution to the sodium sulfate evaporation crystallization unit (2) through the Glauber's salt reflux pipe. The Glauber's salt mother liquor tank (65) is used to store the centrifuged clear liquid. The Glauber's salt mother liquor pump (66) is used to transport the centrifuged clear liquid to the sodium sulfate freeze crystallization unit (5) through the centrifuged clear liquid reflux pipe.

8. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium chloride evaporation and crystallization unit (7) includes a sodium chloride crystallizer (71), a sodium chloride forced circulation evaporator (72), a sodium chloride forced circulation pump (73), and a sodium chloride discharge pump (74). The sodium chloride crystallizer (71) and the sodium chloride forced circulation evaporator (72) are connected by the sodium chloride forced circulation pump (73). The sodium chloride forced circulation pump (73) is used to circulate the liquid in the sodium chloride crystallizer (71), so that the liquid forms sodium chloride crystals in the sodium chloride forced circulation evaporator (72), and returns the sodium chloride crystals to the sodium chloride crystallizer (71) to obtain sodium chloride slurry. The steam generated by the sodium chloride crystallizer (71) is used to transport to the sodium chloride recovery heat exchange unit (8), and the sodium chloride discharge pump (74) is used to transport the sodium chloride slurry from the sodium chloride crystallizer (71) to the sodium chloride post-treatment unit (9).

9. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium chloride recovery heat exchange unit (8) includes a sodium chloride compressor (81) and a sodium chloride scrubbing tower (82). The sodium chloride scrubbing tower (82) is used to receive the steam discharged from the sodium chloride evaporation and crystallization unit (7). The sodium chloride compressor (81) is used to pressurize and heat the gas transported by the sodium chloride scrubbing tower (82) and transport the pressurized and heated steam to the sodium chloride evaporation and crystallization unit (7).

10. The sodium sulfate and sodium chloride high-salt wastewater evaporation crystallization and salt separation treatment system according to claim 1, characterized in that, The sodium chloride post-treatment unit (9) includes a sodium chloride thickener (91), a sodium chloride centrifuge (92), a sodium chloride dryer (93), a sodium chloride mother liquor tank (94), and a sodium chloride mother liquor pump (95). The sodium chloride thickener (91) is connected to the sodium chloride centrifuge (92), the solid output end of the sodium chloride centrifuge (92) is connected to the sodium chloride dryer (93), and the liquid output end of the sodium chloride centrifuge (92) is connected to the sodium chloride mother liquor tank (94). The sodium chloride centrifuge (92) is used to process the sodium chloride slurry. The process involves centrifugation to obtain wet sodium chloride salt and sodium chloride mother liquor; the sodium chloride dryer (93) is used to dry the wet sodium chloride salt to obtain dry sodium chloride salt; the sodium chloride mother liquor tank (94) is used to store the sodium chloride mother liquor; the input end of the sodium chloride mother liquor pump (95) is connected to the sodium chloride mother liquor tank (94); one output end of the sodium chloride mother liquor pump (95) is connected to the sodium chloride evaporation and crystallization unit (7) through the sodium chloride mother liquor reflux pipe; and the other output end of the sodium chloride mother liquor pump (95) is connected to the miscellaneous salt treatment unit (10). The mixed salt processing unit (10) includes a mother liquor dryer (101), which is a scraper drum dryer or a rake dryer. The mother liquor dryer (101) is used to dry the sodium chloride mother liquor and output mixed salt.

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