High-salinity wastewater treatment process based on low-temperature evaporation

Abstract

The invention belongs to the technical field of wastewater treatment, and provides a high-salinity wastewater treatment process based on low-temperature evaporation, which comprises the following steps: S1, after industrial wastewater passes through a reverse osmosis membrane system, further concentrating feed liquid with relatively low concentration to produce wastewater and pure water with relatively high concentration, and recycling the pure water at the front end, high-salinity wastewater enters a stock solution tank to be collected; s2, the high-salinity wastewater in the stock solution tank is conveyed to a refrigerating unit through a stock solution circulating pump for backflow, and the refrigerating unit preheats the stock solution while refrigerating circulating water. Compared with the prior art, the invention has the following beneficial effects: mother liquor is added into the distillation kettle, and the mother liquor, slurry and salt are pushed to move in different directions through the first spiral blade and the second spiral blade, so that materials in the distillation kettle can form uninterrupted circulating movement, and the materials can fully exchange heat with a refrigerant; and insufficient heat exchange caused by material accumulation is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a high-salt wastewater treatment process based on low-temperature evaporation. Background Art

[0002] Generally, after general industrial wastewater is pretreated by physicochemical methods (filtration, precipitation, coagulation, oxidation), substances such as impurities, heavy metals, calcium and magnesium suspended solids, and organic substances are removed, and a large amount of high-salt wastewater (such as sodium chloride, sodium sulfate, ammonium chloride, ammonium sulfate, etc.) is generated. Conventional subsequent treatments generally use processes such as RO membrane concentration, multi-effect evaporation, and MVR evaporation to separate the brine, and the produced industrial salt is recycled and sold, and the produced water is reused.

[0003] When treating high-salt wastewater by low-temperature evaporation, it is necessary to distill the mother liquor through a distillation kettle. Most of the existing distillation kettles drive the flow of the mother liquor inside the distillation kettle through spiral blades. However, when the mother liquor gradually decreases to form slurry and salt, at this time, the slurry and salt can only move to one end under the drive of the spiral blades, and the slurry and salt cannot flow and circulate inside the distillation kettle. As a result, the slurry and salt will accumulate at one end of the distillation kettle, so that the spiral blades need to be frequently reversed. However, it takes time for the spiral blades to reverse, and it also takes time for the accumulated materials to disperse. Moreover, each rotation of the spiral blades will cause the slurry and salt to accumulate, resulting in uneven heat exchange between the slurry and the refrigerant, and reducing the distillation efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-salt wastewater treatment process based on low-temperature evaporation, aiming to solve the technical problem that uneven heat exchange caused by material accumulation in the prior art reduces the distillation efficiency.

[0005] The present invention is realized as follows. A high-salt wastewater treatment process based on low-temperature evaporation, the process comprising the following steps:

[0006] Step S1: After the industrial wastewater passes through the reverse osmosis membrane system, the relatively low-concentration liquid is further concentrated to produce relatively high-concentration wastewater and pure water. The pure water is recycled to the front end, and the high-salt wastewater is collected in the raw liquid tank.

[0007] Step S2: The high-salt wastewater in the raw liquid tank is pumped by the raw liquid circulation pump to the refrigeration unit for reflux. The refrigeration unit preheats the raw liquid while cooling the circulating water.

[0008] Step S3: When the raw liquid in the raw liquid tank is preheated to the set temperature, start the first water production pump. The condensed water in the first water production tank is transported to the vacuum device for circulation through the first water production. Open the vacuum pumping valve, and the inside of the first separator gradually approaches the vacuum state. Open the raw liquid feed valve, and the liquid in the raw liquid tank enters the first separator. After the liquid level in the first separator reaches the set height, start the circulation pump, and the liquid is circulated through the first heat exchanger.

[0009] Step S4: Start the compressor in the heat pump system, and the low-temperature and low-pressure gaseous refrigerant is compressed and sucked in, and then compressed, and then sent to the first heat exchanger to heat the wastewater through the oil separator. The liquid that receives the heat returns to the first separator and continues to evaporate at the set temperature. At the same time, the gaseous refrigerant is condensed into liquid in the first heat exchanger, and then enters the second heat exchanger after being cooled and decompressed by the expansion valve;

[0010] Step S5: The secondary steam generated by evaporation in the first separator passes through the top wire mesh demister to eliminate gas phase entrainment, and then enters the second heat exchanger to provide heat to the liquid refrigerant. The liquid refrigerant receives the heat and evaporates, then turns back into low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped to the first water production tank by the vacuum equipment. After the liquid level in the first water production tank reaches the set height, it is discharged through the water production external discharge valve;

[0011] Step S6: The salt concentration of the feed liquid in the first separator is continuously concentrated until the saturated concentration is reached and the crystalline salt begins to precipitate through continuous evaporation. After reaching the set solid content, the salt is pumped into a centrifuge for salt separation through a salt discharge pump, and the crystallized salt is packaged and shipped out. The enriched mother liquor is discharged into a mother liquor tank and pumped into a distillation kettle for treatment through a mother liquor pump;

[0012] Step S7: The condensed water in the second water production tank is transported to the vacuum equipment through the second water production tank for circulation, the vacuum degree in the distillation kettle increases, the electric heating in the heating tank is started, the water in the heating tank generates steam and is sucked by the vacuum equipment, and exchanges heat with the refrigerant through the third heat exchanger, and the refrigerant is preheated to the set temperature;

[0013] Step S8: Start the compressor, compress the low-temperature and low-pressure gaseous refrigerant into a high-temperature and high-pressure gaseous refrigerant, and enter the jacket outside the distillation kettle through the oil separator. At the same time, the feed liquid in the distillation kettle is stirred, and the refrigerant and the feed liquid are fully exchanged with each other. The gaseous refrigerant is condensed into liquid in the jacket, and enters the third heat exchanger after being cooled and decompressed by the expansion valve;

[0014] Step S9: The secondary steam generated by evaporation in the distillation kettle passes through the wire mesh demister at the top of the second separator to eliminate gas phase entrainment, and then enters the third heat exchanger to provide heat to the liquid refrigerant. The liquid refrigerant receives the heat and evaporates, and then turns back into a low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped to the second water production tank by the vacuum equipment. After the liquid level in the second water production tank reaches the set height, it is discharged through the water production external discharge valve;

[0015] Step S10: the enriched mother liquor in the distillation kettle is continuously evaporated, and the salt in the feed liquid is continuously precipitated to first become a slurry, and then further dried to form dry salt, and then the dry salt in the distillation kettle is discharged and collected;

[0016] A jacket is provided on the outer side of the distillation kettle. A blanking chute is provided on one side of the distillation kettle, and a closing plate is provided in the blanking chute. A stirring shaft driven by a first rotating power member is rotatably installed in the distillation kettle. A first spiral blade is fixedly installed on the stirring shaft. There are intervals between the first spiral blade and the stirring shaft and the inner wall of the distillation kettle. Installation rings are rotatably installed at both ends of the stirring shaft. A bracket is fixedly installed on the installation ring. Two groups of brackets are jointly fixedly installed with a second spiral blade. The second spiral blade is in sliding contact with the outer side of the first spiral blade. There is a gap between the second spiral blade and the inner wall of the distillation kettle. When the second spiral blade and the first spiral blade are in a set position, a complete spiral structure is formed. A power assembly for driving the installation ring to rotate is provided on the distillation kettle.

[0017] Further technical solution: The power assembly includes a second rotating power member. The second rotating power member is fixedly installed on the side wall of the distillation kettle. The output shaft of the second rotating power member extends into the distillation kettle and its output shaft is parallel to the stirring shaft. A gear is fixedly installed at the end of the output shaft of the second rotating power member. The gear meshes with a toothed ring fixedly installed on the installation ring. The toothed ring and the installation ring are coaxially arranged.

[0018] Further technical solution: A rotating ring is fixedly installed on the bracket. The rotating ring and the stirring shaft are coaxially arranged. A plurality of uniformly distributed scraping plates are fixedly installed on the rotating ring. The scraping plates are in sliding contact with the inner wall of the distillation kettle.

[0019] Further technical solution: The rotation trajectory of the scraping plate covers the area from the end of the second spiral blade to the end of the distillation kettle.

[0020] Further technical solution: A guide plate is fixedly installed on the surface of the scraping plate on the front side of the rotation direction. The guide plate forms an angle with the side wall of the distillation kettle. The guide plate is in sliding contact with the inner wall of the distillation kettle. The opening of the guide plate and the inner wall of the distillation kettle faces away from the end of the distillation kettle.

[0021] Further technical solution: A first telescopic member is fixedly installed at the end of the distillation kettle. The output end of the first telescopic member is fixedly connected to the closing plate.

[0022] Further technical solution: A clamping groove is formed on the inner side surface of the closing plate located in the distillation kettle. An arc-shaped cleaning plate is slidably installed in the clamping groove. A second telescopic member for driving the cleaning plate to move is fixedly installed on the closing plate.

[0023] Further technical solution: A connecting rod is fixedly installed at the output end of the second telescopic member. The connecting rod is parallel to the second telescopic member. The connecting rod is slidably connected to the closing plate and the connecting rod is fixedly connected to the cleaning plate. The connecting rod forms an angle with the stirring shaft. When the cleaning plate moves away from the closing plate, the distance between it and the bottom side wall of the distillation kettle decreases.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. Add the mother liquor into the distillation kettle, and push the mother liquor, slurry, and salt in different directions through the first spiral blade and the second spiral blade, so that the materials in the distillation kettle can form an uninterrupted cyclic movement, enabling the materials to fully exchange heat with the refrigerant, avoiding insufficient heat exchange caused by material accumulation, and improving the distillation efficiency of the materials.

[0026] 2. When the second spiral blade rotates, it drives the multiple scrapers to rotate synchronously through the rotating ring. When the scraper rotates upward from the bottom of the distillation kettle, it drives the slurry and salt to move upward. When the scraper rotates to a downward inclination, under the action of gravity, the slurry and salt on it will descend along the scraper and fall in the direction away from the end of the distillation kettle under the action of the guide plate, enabling the materials at the end of the distillation kettle to move to the coverage area of the first spiral blade and the second spiral blade again. Subsequently, the first spiral blade and the second spiral blade can continue to push the materials to continue participating in the cyclic movement, avoiding the accumulation of materials at the end of the distillation kettle and being unable to participate in the material cycle, further improving the uniformity of heat exchange between the materials and the refrigerant, and enhancing the distillation effect.

[0027] 3. When a large amount of dry salt in the distillation kettle leaves the distillation kettle, some dry salt will remain at the position where the first spiral blade and the second spiral blade at the end of the distillation kettle cannot cover. At this time, the first telescopic member first drives the closing plate to reset, and then the second telescopic member contracts and drives the cleaning plate to move through the connecting rod. When the cleaning plate moves away from the closing plate, it will gradually approach the bottom of the distillation kettle. When the cleaning plate contacts the bottom of the distillation kettle, it stops moving. At this time, the first telescopic member drives the closing plate to move away from the distillation kettle again, and the cleaning plate will move synchronously. The dry salt remaining at the end of the distillation kettle is scraped out by the cleaning plate, enabling the dry salt to completely leave the distillation kettle and avoiding the influence of residual dry salt in the distillation kettle on subsequent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the salt separation system in the present invention.

[0029] Figure 2 It is a flowchart of the mother liquor treatment system in the present invention.

[0030] Figure 3 It is a schematic structural diagram of the distillation kettle in the present invention.

[0031] Figure 4 It is a schematic cross-sectional structural diagram of the distillation kettle in the present invention.

[0032] Figure 5 It is a schematic structural diagram of the first stirring blade and the second stirring blade in the present invention.

[0033] Figure 6 is Figure 4Enlarged schematic view of area A1 in [the figure].

[0034] Figure 7 It is Figure 4 Enlarged schematic view of area A2 in [the figure].

[0035] In the attached drawings: 1. Stock solution tank; 2. Stock solution circulation pump; 3. Refrigeration unit; 4. First water production pump; 5. First water production tank; 6. First separator; 7. Circulation pump; 8. First heat exchanger; 9. Second heat exchanger; 10. Brine discharge pump; 11. Mother liquid tank; 12. Distillation kettle; 13. Second separator; 14. Second water production tank; 15. Second water production pump; 16. Heating tank; 17. Third heat exchanger; 18. Stirring shaft; 19. First spiral blade; 20. First rotary power component; 21. Installation ring; 22. Gear ring; 23. Gear; 24. Second rotary power component; 25. Bracket; 26. Second spiral blade; 27. Rotating ring; 28. Scraper; 29. Guide plate; 30. Sealing plate; 31. First telescopic component; 32. Second telescopic component; 33. Connecting rod; 34. Cleaning plate; 35. Card slot; 36. Power component. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the attached drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0038] As Figures 1-7 shown, a high-salt wastewater treatment process based on low-temperature evaporation provided by the present invention includes the following steps:

[0039] Step S1: After the industrial wastewater passes through the reverse osmosis membrane system, the relatively low-concentration feed liquid is further concentrated to produce relatively high-concentration wastewater and pure water. The pure water is recycled to the front end, and the high-salt wastewater is collected in the stock solution tank 1.

[0040] Step S2: The high-salt wastewater in the stock solution tank 1 is transported by the stock solution circulation pump 2 to the refrigeration unit 3 for reflux. While cooling the circulating water, the refrigeration unit 3 preheats the stock solution.

[0041] Step S3: When the stock solution in the stock solution tank 1 is preheated to the set temperature, start the first water production pump 4. The condensed water in the first water production tank 5 is circulated through the first water production pump 4 via a vacuum device. Open the vacuum extraction valve, and the inside of the first separator 6 gradually approaches the vacuum state. Open the stock solution feed valve, and the feed liquid in the stock solution tank 1 enters the first separator 6. After the liquid level in the first separator 6 reaches the set height, start the circulation pump 7, and the feed liquid is circulated through the first heat exchanger 8.

[0042] Step S4: Start the compressor in the heat pump system, and the low-temperature and low-pressure gaseous refrigerant is compressed and sucked in, and then compressed, and then sent to the first heat exchanger 8 to heat the wastewater through the oil separator. The liquid that receives the heat returns to the first separator 6 and continues to evaporate at the set temperature. At the same time, the gaseous refrigerant is condensed into liquid in the first heat exchanger 8, and then enters the second heat exchanger 9 after being cooled and decompressed by the expansion valve;

[0043] Step S5: The secondary steam generated by evaporation in the first separator 6 passes through the top wire mesh demister to eliminate gas phase entrainment, and then enters the second heat exchanger 9 to provide heat to the liquid refrigerant. The liquid refrigerant receives the heat and evaporates, and then turns back into a low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped to the first water production tank 5 by the vacuum equipment. After the liquid level in the first water production tank 5 reaches the set height, it is discharged through the water production valve;

[0044] Step S6: The salt concentration of the feed liquid in the first separator 6 is continuously concentrated until the saturated concentration is reached and the crystalline salt begins to precipitate through continuous evaporation. After reaching the set solid content, the salt is pumped into the centrifuge for salt separation through the salt discharge pump 10, and the crystallized salt is packaged and shipped out. The enriched mother liquor is discharged into the mother liquor tank 11 and pumped into the distillation kettle 12 for treatment through the mother liquor pump;

[0045] Step S7: The condensed water in the second water production tank 14 is circulated through the vacuum equipment by the second water production pump 15, the vacuum degree in the distillation kettle 12 is increased, the electric heating in the heating tank 16 is started, the water in the heating tank 16 generates steam and is sucked by the vacuum equipment, and exchanges heat with the refrigerant through the third heat exchanger 17, and the refrigerant is preheated to the set temperature;

[0046] Step S8: Start the compressor, the low-temperature and low-pressure gaseous refrigerant is compressed into a high-temperature and high-pressure gaseous refrigerant, and enters the jacket outside the distillation kettle 12 through the oil separator, and at the same time, the feed liquid in the distillation kettle 12 is stirred, and the refrigerant and the feed liquid are fully exchanged with each other. The gaseous refrigerant is condensed into liquid in the jacket, and enters the third heat exchanger 17 after being cooled and decompressed by the expansion valve;

[0047] Step S9: The secondary steam generated by evaporation in the distillation kettle 12 passes through the wire mesh demister at the top of the second separator 13 to eliminate gas phase entrainment, and then enters the third heat exchanger 17 to provide heat to the liquid refrigerant. The liquid refrigerant receives the heat and evaporates, and then turns back into a low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped to the second water production tank 14 by the vacuum equipment. After the liquid level in the second water production tank 14 reaches the set height, it is discharged through the water production valve;

[0048] Step S10: the enriched mother liquid in the distillation kettle 12 is continuously evaporated, and the salt in the liquid is continuously precipitated to first become a slurry, and then further dried to form dry salt, and then the dry salt in the distillation kettle 12 is discharged and collected;

[0049] A jacket is provided outside the distillation kettle 12. A blanking chute is provided on one side of the distillation kettle 12, and a closing plate 30 is provided in the blanking chute. A stirring shaft 18 driven by a first rotating power member 20 is rotatably installed in the distillation kettle 12. A first spiral blade 19 is fixedly installed on the stirring shaft 18. The first spiral blade 19 has intervals with both the stirring shaft 18 and the inner wall of the distillation kettle 12. Installation rings 21 are rotatably installed at both ends of the stirring shaft 18. A bracket 25 is fixedly installed on the installation ring 21. Two groups of brackets 25 jointly fixedly install a second spiral blade 26. The second spiral blade 26 is in sliding contact with the outside of the first spiral blade 19. The second spiral blade 26 has a gap with the inner wall of the distillation kettle 12. When the second spiral blade 26 and the first spiral blade 19 are in a set position, a complete spiral structure is formed. A power assembly 36 for driving the installation ring 21 to rotate is provided on the distillation kettle 12.

[0050] In actual application of this embodiment, when the mother liquor enters the distillation kettle 12, the first rotating power member 20 drives the stirring shaft 18 to rotate, thereby driving the first spiral blade 19 to rotate. The power assembly 36 drives the installation ring 21 to rotate, thereby driving the second spiral blade 26 to rotate. The rotation directions of the first spiral blade 19 and the second spiral blade 26 are opposite. When the second spiral blade 26 rotates, it pushes the mother liquor in the direction of the closing plate 30. When there is more mother liquor in the distillation kettle 12, the first spiral blade 19 and the second spiral blade 26 drive the mother liquor to circulate, so that the mother liquor can fully exchange heat with the refrigerant in the jacket. As the mother liquor in the distillation kettle 12 continuously evaporates, the salt in the mother liquor first precipitates into a slurry and then is further dried to form dry salt. The slurry and the dry salt will both be present at the bottom of the distillation kettle 12. When there are slurry and salt in the distillation kettle 12, the second spiral blade 26 pushes a part of the slurry and salt at the bottom to move, and the first spiral blade 19 pushes the slurry and salt at the upper part to move. Moreover, the moving directions of the slurry and salt pushed by the first spiral blade 19 and the second spiral blade 26 are opposite, so that the slurry and salt can reciprocally circulate and move in the distillation kettle 12, ensuring that the slurry and the wet salt can continue to fully exchange heat with the refrigerant. Finally, only dry salt remains in the distillation kettle 12. By pushing the mother liquor, slurry, and salt to move in different directions with the first spiral blade 19 and the second spiral blade 26, the materials in the distillation kettle 12 can form an uninterrupted cyclic movement, enabling the materials to fully exchange heat with the refrigerant, avoiding insufficient heat exchange caused by material accumulation, and improving the distillation efficiency of the materials. When only dry salt remains in the distillation kettle 12, the closing plate 30 is opened. When the stirring shaft 18 rotates to the initial position and stops rotating, and when the second spiral blade 26 rotates to the initial position, the stirring shaft 18 rotates in the reverse direction and the rotation speed is the same as that of the second spiral blade 26. At this time, the first spiral blade 19 and the second spiral blade 26 form a complete spiral structure. At this time, the dry salt in the distillation kettle 12 is jointly pushed by the first spiral blade 19 and the second spiral blade 26 to move towards the blanking chute side and leave the distillation kettle 12 through the blanking chute;

[0051] While the refrigeration unit 3 produces cooling water, it preheats the stock solution. Compared with dissipating heat through air cooling, which causes waste, it is more energy-efficient. The refrigerant with a high condensation temperature needs to be preheated before startup. Water is heated by electric heating, vaporized under the vacuum degree generated by the vacuum equipment, and attracted to the second heat exchanger 9 to preheat the refrigerant. Utilizing the characteristics of high enthalpy of steam, it has a higher preheating efficiency than traditional hot water preheating and saves the hot water circulation pump.

[0052] In an example of this embodiment, the first rotating power member 20 is a first motor. Of course, it can also be other components such as a hydraulic motor that can output rotational power. The first motor drives the first spiral blade 19 to rotate. A secondary steam condenser is connected in parallel to the secondary steam outlets of the first separator 6 and the second separator 13. The high-pressure balance regulating valve is used to balance the heat generated additionally by the compressor to avoid excessive high pressure. The hot gas bypass pipeline is used to avoid excessive low pressure. The secondary steam condenser not only balances the additional heat generated by the compressor but also increases the water production. Compared with traditional refrigeration systems that dissipate heat through air cooling or plate heat exchangers, it is more energy-efficient and improves the processing efficiency.

[0053] As Figure 4 、 Figure 6 shown, a high-salt wastewater treatment process based on low-temperature evaporation provided by the present invention. The power assembly 36 includes a second rotating power member 24. The second rotating power member 24 is fixedly installed on the side wall of the distillation kettle 12. The output shaft of the second rotating power member 24 extends into the distillation kettle 12 and its output shaft is parallel to the stirring shaft 18. A gear 23 is fixedly installed at the end of the output shaft of the second rotating power member 24. The gear 23 meshes with a toothed ring 22 fixedly installed on the mounting ring 21. The toothed ring 22 and the mounting ring 21 are coaxially arranged.

[0054] In actual application of this embodiment, the second rotating power member 24 drives the mounting ring 21 to rotate through the meshing gear 23 and toothed ring 22. Then, the mounting ring 21 drives the second spiral blade 26 to rotate through the bracket 25.

[0055] In an example of the present invention, the second rotating power member 24 is a second motor. Of course, it can also be other components such as a hydraulic motor that can output rotational power. The second motor drives the second spiral blade 26 to rotate.

[0056] As Figure 4 、 Figure 5 shown, a high-salt wastewater treatment process based on low-temperature evaporation provided by the present invention. A rotating ring 27 is fixedly installed on the bracket 25. The rotating ring 27 and the stirring shaft 18 are coaxially arranged. A plurality of evenly distributed scraping plates 28 are fixedly installed on the rotating ring 27. The scraping plates 28 are in sliding contact with the inner wall of the distillation kettle 12.

[0057] Specifically, the rotation trajectory of the scraper 28 covers the area from the end of the second spiral blade 26 to the end of the distillation kettle 12.

[0058] Specifically, a guide plate 29 is fixedly installed on the surface of the front side of the scraper 28 in the rotation direction. The guide plate 29 forms an angle with the side wall of the distillation kettle 12. The guide plate 29 is in sliding contact with the inner wall of the distillation kettle 12, and the opening of the guide plate 29 and the inner wall of the distillation kettle 12 faces away from the end of the distillation kettle 12.

[0059] In actual application of this embodiment, when the second spiral blade 26 rotates, it drives the multi-scrapers 28 to rotate synchronously through the rotating ring 27. When the scraper 28 rotates upward from the bottom of the distillation kettle 12, it drives the slurry and salt to move upward. When the scraper 28 rotates to a downward inclination, under the action of gravity, the slurry and salt on it will descend along the scraper 28 and fall in the direction away from the end of the distillation kettle 12 under the action of the guide plate 29, so that the materials located at the end of the distillation kettle 12 can move to the covered area of the first spiral blade 19 and the second spiral blade 26 again. Subsequently, the first spiral blade 19 and the second spiral blade 26 can continue to push the materials to continue participating in the cyclic movement, avoiding the accumulation of materials at the end of the distillation kettle 12 and being unable to participate in the material cycle, further improving the uniformity of heat exchange between the materials and the refrigerant, and improving the distillation effect.

[0060] As Figure 3 、 Figure 4 、 Figure 7 As shown, a first telescopic member 31 is fixedly installed at the end of the distillation kettle 12 provided by the present invention for a high-salt wastewater treatment process based on low-temperature evaporation. The output end of the first telescopic member 31 is fixedly connected to the closing plate 30.

[0061] Specifically, a card slot 35 is formed on the side surface of the closing plate 30 located inside the distillation kettle 12. An arc-shaped cleaning plate 34 is slidably installed in the card slot 35. A second telescopic member 32 for driving the cleaning plate 34 to move is fixedly installed on the closing plate 30.

[0062] Specifically, a connecting rod 33 is fixedly installed at the output end of the second telescopic member 32. The connecting rod 33 is parallel to the second telescopic member 32. The connecting rod 33 is slidably connected to the closing plate 30 and fixedly connected to the cleaning plate 34. The connecting rod 33 forms an angle with the stirring shaft 18. When the cleaning plate 34 moves away from the closing plate 30, the distance between it and the bottom side wall of the distillation kettle 12 decreases.

[0063] In practical application of this embodiment, when only dry salt remains in the distillation kettle 12, the first telescopic member 31 extends to drive the closing plate 30 to move away from the distillation kettle 12, so that the blanking chute is opened. At this time, the dry salt in the distillation kettle 12 can leave through the blanking chute. After a large amount of dry salt in the distillation kettle 12 leaves the distillation kettle 12, some dry salt will remain at the position that cannot be covered by the first spiral blade 19 and the second spiral blade 26 at the end of the distillation kettle 12. At this time, the first telescopic member 31 first drives the closing plate 30 to reset, and then the second telescopic member 32 contracts and drives the cleaning plate 34 to move through the connecting rod 33. When the cleaning plate 34 moves away from the closing plate 30, it will gradually approach the bottom of the distillation kettle 12. When the cleaning plate 34 contacts the bottom of the distillation kettle 12, it stops moving. At this time, the first telescopic member 31 drives the closing plate 30 to move away from the distillation kettle 12 again, and the cleaning plate 34 will move synchronously. The remaining dry salt at the end of the distillation kettle 12 is scraped out by the cleaning plate 34, so that the dry salt can completely leave the distillation kettle 12, avoiding the influence of residual dry salt in the distillation kettle 12 on subsequent use.

[0064] In an example of the present invention, the first telescopic member 31 and the second telescopic member 32 are respectively a first electric telescopic rod and a second electric telescopic rod. Of course, they can also be other components such as hydraulic cylinders that can actively change their lengths. The closing plate 30 is driven to move by the first electric telescopic rod, and the cleaning plate 34 is driven to move by the second electric telescopic rod.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0066] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-salinity wastewater treatment process based on low-temperature evaporation, characterized in that: The process comprises the following steps: Step S1: After the industrial wastewater passes through the reverse osmosis membrane system, the relatively low-concentration feed liquid is further concentrated to produce relatively high-concentration wastewater and pure water. The pure water is reused at the front end, and the high-salt wastewater is collected in the stock liquid tank (1); Step S2: The high-salt wastewater in the stock liquid tank (1) is transported to the refrigeration unit (3) for reflux through the stock liquid circulation pump (2). The refrigeration unit (3) preheats the stock liquid while refrigerating the circulating water; Step S3: When the raw liquid in the raw liquid tank (1) is preheated to a set temperature, the first water production pump (4) is started, and the condensed water in the first water production tank (5) is circulated through the first water production pump (4) through the vacuum equipment, and the vacuum valve is opened, and the first separator (6) gradually approaches a vacuum state, and the raw liquid feed valve is opened, and the raw liquid in the raw liquid tank (1) enters the first separator (6). After the liquid level in the first separator (6) reaches a set height, the circulation pump (7) is started, and the raw liquid is circulated through the first heat exchanger (8); Step S4: starting the compressor in the heat pump system, the low-temperature and low-pressure gaseous refrigerant is compressed and sucked in, and then compressed, and then sent to the first heat exchanger (8) through the oil separator to heat the wastewater. The liquid that receives the heat returns to the first separator (6) and continues to evaporate at the set temperature. At the same time, the gaseous refrigerant is condensed into liquid in the first heat exchanger (8), and then enters the second heat exchanger (9) after being cooled and decompressed by the expansion valve; Step S5: The secondary steam generated by evaporation in the first separator (6) passes through the top wire mesh demister to eliminate gas phase entrainment, and then enters the second heat exchanger (9) to provide heat to the liquid refrigerant. After the liquid refrigerant receives the heat and evaporates, it turns back into a low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped into the first water production tank (5) by the vacuum equipment. After the liquid level in the first water production tank (5) reaches the set height, it is discharged through the water production valve; Step S6: The salt concentration of the feed liquid in the first separator (6) is continuously concentrated until the saturated concentration is reached and the evaporation continues to cause the precipitation of crystallized salt. After reaching the set solid content, the salt is pumped into a centrifuge for salt separation through a salt discharge pump (10), and the crystallized salt is packaged and shipped out. The enriched mother liquor is discharged into a mother liquor tank (11), and then pumped into a distillation kettle (12) for treatment through a mother liquor pump; Step S7: the condensed water in the second water production tank (14) is circulated through the second water production pump (15) via the vacuum device, the vacuum degree in the distillation kettle (12) increases, the electric heating in the heating tank (16) is started, the water in the heating tank (16) generates steam and is sucked by the vacuum device, and heat is exchanged with the refrigerant through the third heat exchanger (17), and the refrigerant is preheated to a set temperature; Step S8: starting the compressor, compressing the low-temperature and low-pressure gaseous refrigerant into a high-temperature and high-pressure gaseous refrigerant, and entering the jacket outside the distillation kettle (12) through the oil separator. At the same time, the feed liquid in the distillation kettle (12) is stirred, and the refrigerant and the feed liquid are fully exchanged with each other. The gaseous refrigerant is condensed into a liquid in the jacket, and enters the third heat exchanger (17) after being cooled and decompressed by the expansion valve; Step S9: The secondary steam generated by evaporation in the distillation kettle (12) passes through the wire mesh demister at the top of the second separator (13) to eliminate gas phase entrainment, and then enters the third heat exchanger (17) to provide heat to the liquid refrigerant. After the liquid refrigerant receives the heat and evaporates, it turns back into a low-temperature and low-pressure gaseous refrigerant and returns to the compressor. At the same time, the secondary steam condenses into water and is pumped into the second water production tank (14) by the vacuum equipment. After the liquid level in the second water production tank (14) reaches the set height, it is discharged through the water production valve; Step S10: the enriched mother liquid in the distillation kettle (12) is continuously evaporated, and the salt in the liquid is continuously precipitated to first become a slurry, and then further dried to form dry salt, and then the dry salt in the distillation kettle (12) is discharged and collected; The outside of the distillation kettle (12) is provided with a jacket, one side of the distillation kettle (12) is provided with a material drop trough and a closing plate (30) is provided in the material drop trough, a stirring shaft (18) driven by a first rotating power member (20) is rotatably installed in the distillation kettle (12), a first spiral blade (19) is fixedly installed on the stirring shaft (18), a gap is provided between the first spiral blade (19) and the stirring shaft (18) and the inner wall of the distillation kettle (12), and mounting rings (21) are rotatably installed at both ends of the stirring shaft (18), and the first spiral blade (19) is fixedly installed on the stirring shaft (18). A bracket (25) is fixedly mounted on the mounting ring (21), and a second spiral blade (26) is fixedly mounted on two sets of brackets (25). The second spiral blade (26) is in sliding contact with the outer side of the first spiral blade (19), and a gap is provided between the second spiral blade (26) and the inner wall of the distillation kettle (12). When the second spiral blade (26) and the first spiral blade (19) are located at a set position, a complete spiral structure is formed. The distillation kettle (12) is provided with a power component (36) for driving the mounting ring (21) to rotate.

2. A high-salt wastewater treatment process based on low-temperature evaporation according to claim 1, characterized in that: The power assembly (36) comprises a second rotating power member (24), the second rotating power member (24) is fixedly mounted on the side wall of the distillation kettle (12), the output shaft of the second rotating power member (24) extends into the distillation kettle (12) and the output shaft is parallel to the stirring shaft (18), a gear (23) is fixedly mounted on the end of the output shaft of the second rotating power member (24), the gear (23) is meshed with a gear ring (22) fixedly mounted on the mounting ring (21), and the gear ring (22) and the mounting ring (21) are coaxially arranged.

3. A high-salt wastewater treatment process based on low-temperature evaporation according to claim 1, characterized in that: A rotating ring (27) is fixedly mounted on the bracket (25), the rotating ring (27) is coaxially arranged with the stirring shaft (18), and a plurality of groups of evenly distributed scrapers (28) are fixedly mounted on the rotating ring (27), the scrapers (28) are in sliding contact with the inner wall of the distillation kettle (12).

4. A high-salinity wastewater treatment process based on low-temperature evaporation according to claim 3, characterized in that: The rotation trajectory of the scraper (28) covers the area from the end of the second spiral blade (26) to the end of the distillation kettle (12).

5. A high-salt wastewater treatment process based on low-temperature evaporation according to claim 3, characterized in that: A guide plate (29) is fixedly mounted on the surface of the scraper (28) located on the front side in the direction of rotation. An angle is set between the guide plate (29) and the side wall of the distillation kettle (12). The guide plate (29) is in sliding contact with the inner wall of the distillation kettle (12). The opening between the guide plate (29) and the inner wall of the distillation kettle (12) faces away from the end of the distillation kettle (12).

6. A high-salinity wastewater treatment process based on low-temperature evaporation according to claim 1, characterized in that: A first telescopic member (31) is fixedly mounted on the end of the distillation kettle (12), and an output end of the first telescopic member (31) is fixedly connected to the closing plate (30).

7. A high-salinity wastewater treatment process based on low-temperature evaporation according to claim 6, characterized in that: The side surface of the closing plate (30) located in the distillation kettle (12) is provided with a slot (35), an arc-shaped cleaning plate (34) is slidably installed in the slot (35), and a second telescopic member (32) is fixedly installed on the closing plate (30) to drive the cleaning plate (34) to move.

8. A high-salinity wastewater treatment process based on low-temperature evaporation according to claim 7, characterized in that: A connecting rod (33) is fixedly installed at the output end of the second telescopic member (32), and the connecting rod (33) is parallel to the second telescopic member (32). The connecting rod (33) is slidably connected to the closing plate (30) and the connecting rod (33) is fixedly connected to the cleaning plate (34). An angle is set between the connecting rod (33) and the stirring shaft (18). When the cleaning plate (34) moves in a direction away from the closing plate (30), the distance between it and the bottom side wall of the distillation kettle (12) decreases.

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