A device and method for co-production of non-edible salt and fresh water based on seawater evaporation crystallization

Abstract

The application provides a device and method for co-production of non-edible salt and fresh water based on seawater evaporation crystallization, and relates to the technical field of seawater treatment.The device comprises a separator, a compressor and a falling-film evaporator.The device and method for co-production of non-edible salt and fresh water based on seawater evaporation crystallization are provided, the seawater forming a liquid film is subjected to heating and evaporation treatment through the separator, the compressor, the falling-film evaporator, the support frame, the evaporation disc, the heat transfer mechanism, the guide rod, the wall scraping mechanism and the liquid control mechanism, the evaporation effect is ensured, the seawater is evaporated by using the waste heat of evaporation, energy saving and environmental protection are achieved, the inner wall of the tube bundle can be cleaned and treated, the influence of the fouling of the inner wall of the tube bundle on the heat conduction effect is reduced, the discharge rate of the concentrated liquid generated after evaporation can be controlled according to the crystallization condition, the concentrated liquid is evaporated and crystallized by using the waste heat, the crystallization condition is controlled, and the steam after evaporation and crystallization is condensed into fresh water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seawater treatment, and particularly relates to a device and method for coproduction of non-edible salt and fresh water based on seawater evaporation crystallization. BACKGROUND

[0002] With the increasingly serious problem of global freshwater resource shortage, seawater desalination and salt resource recovery technology has become an important way to solve the water crisis in coastal areas. As of 2025, the global seawater desalination daily output has broken through 35 million cubic meters. However, the traditional technology generally has problems of high energy consumption and low utilization efficiency of by-products. Non-edible salt, as an important by-product of seawater desalination, is widely used in industrial production (such as chemical raw materials, snow melting agent) and agricultural fields.

[0003] Currently, the mainstream seawater desalination technologies include reverse osmosis (RO), multi-stage flash evaporation (MSF) and multi-effect distillation (MED). Although the reverse osmosis technology has low energy consumption (1-5 kWh / m³), it needs pretreatment to remove suspended solids and colloids, and improper treatment of concentrated brine can easily cause secondary pollution. The multi-stage flash evaporation and multi-effect distillation rely on heat energy driving, and the energy consumption is as high as 12.7-15.0 kWh / m³, and the equipment investment and land occupation are large. In addition, the MVR (mechanical vapor recompression) technology can also be used in the field of seawater desalination. In the MVR technology, the falling film evaporator relies on the film distributor to uniformly distribute seawater to the inlet of each tube bundle, and a conical flow guide cap is used to form a continuous liquid film on the inner wall of the tube bundle. After long-term use, the inner wall of the tube bundle may be scaled (calcium and magnesium ions (total hardness 1.2-1.8 g / L in terms of CaCO3), sulfate (2.7-3.0 g / L in terms of SO4 2- When the liquid film is heated and evaporated on the inner wall of the tube bundle, the water rapidly vaporizes, causing a sudden increase in local concentration: calcium carbonate (CaCO3) has a significantly decreased solubility at a temperature >60℃, and is easy to form hard scale (thermal conductivity is only 0.5-1.0 W / (m·K), which is 1 / 50-1 / 100 of carbon steel) on the heat transfer surface; magnesium sulfate (MgSO4) is easy to form needle-shaped crystals when the supersaturation degree >1.5, and is attached to the tube wall with the liquid film, especially in the area where the liquid film is thin; if the thickness of the liquid film is uneven (such as locally thinner than 0.3 mm), the heat transfer rate in this area suddenly increases (the heat flux can reach 5000-8000 W / m²), causing instantaneous evaporation of water, and the salts are attached to the tube wall in the form of "spattering crystallization"; in addition, the greater the temperature difference (usually 10-30℃) between the heat transfer surface and the liquid film, the stronger the supersaturation driving, and the scaling rate increases exponentially (for every 5℃ increase in temperature difference, the scaling rate increases by about 20%), etc. After scaling, the heat transfer efficiency is greatly reduced, the evaporation capacity is attenuated, the energy consumption is increased, and the operating cost is increased. SUMMARY

[0004] Based on the technical problems existing in the background art, the present application proposes a device and method for co-production of non-edible salt and fresh water based on seawater evaporation crystallization.

[0005] The device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization proposed by the present application comprises a separator, a compressor and a falling film evaporator, the falling film evaporator comprises a processing cylinder, a first baffle, a second baffle and a tube bundle; the first baffle and the second baffle are fixedly installed in the processing cylinder, and the first baffle and the second baffle divide the processing cylinder into a liquid distribution cavity, a heating cavity and a liquid falling cavity arranged in an upper-middle-lower manner; the tube bundle is located in the heating cavity; the two ends of the tube bundle respectively penetrate through the first baffle and the second baffle and communicate with the liquid distribution cavity and the liquid falling cavity; the separator communicates with the liquid falling cavity; the separator communicates with the compressor; and the compressor communicates with the heating cavity.

[0006] A support frame is arranged directly below the processing cylinder, an evaporation disc is installed on the support frame in a lifting manner, a evaporation groove is formed in the top surface of the evaporation disc, and a heat transfer mechanism is arranged between the processing cylinder and the evaporation disc; the heat transfer mechanism is used for transferring the steam heat in the heating cavity to the evaporation disc.

[0007] A vertically arranged guide rod is fixedly connected to the evaporation disc, the guide rod slidably penetrates through the bottom of the processing cylinder and extends into the tube bundle, a wall scraping mechanism is arranged in the tube bundle, and the wall scraping mechanism can scrape the inner wall of the tube bundle; when the guide rod moves up and down, the guide rod can drive the wall scraping mechanism to operate.

[0008] A liquid control mechanism is installed on the processing cylinder, and the liquid control mechanism is used for discharging the water in the liquid falling cavity to the evaporation groove; when the guide rod moves up and down, the guide rod can drive the liquid control mechanism to move.

[0009] Preferably, the falling film evaporator further comprises a membrane distributor, the membrane distributor is fixedly installed in the liquid distribution cavity, and the membrane distributor is used for uniformly distributing seawater to the first baffle.

[0010] Preferably, the wall scraping mechanism comprises a sleeve rod, a scraping block, an anti-slip block, a retraction spring, an ejection assembly and a rotary guide assembly; the sleeve rod is located in the tube bundle and is sleeved on the guide rod; the two sides of the sleeve rod are both provided with a receiving groove capable of receiving the scraping block; the anti-slip block is fixedly connected to the side surface of the scraping block; the inner wall of the receiving groove is provided with a limiting sliding groove in sliding cooperation with the anti-slip block; and the retraction spring is located in the limiting sliding groove and has two ends respectively connected to the anti-slip block and the end inner wall of the limiting sliding groove.

[0011] When the guide rod moves downward, the scraping block is pushed by the ejection assembly to slide out of the receiving groove and abuts against the inner wall of the tube bundle.

[0012] When the guide rod is lowered, the scraping block can also be rotated by the rotating guide assembly to scrape the inner wall of the pipe bundle.

[0013] Preferably, the ejection assembly comprises an ejection inclined block fixedly connected to the outer periphery of the guide rod, and a trapezoidal slot is formed in the scraping block to slidably cooperate with the ejection inclined block.

[0014] Preferably, the rotating guide assembly comprises a connecting sleeve fixedly connected to the bottom surface of the film distributor, a sleeve rod rotatably connected to the bottom end of the connecting sleeve, and a sliding shaft fixedly connected to the outer periphery of the guide rod, wherein a lifting hole slidably cooperating with the guide rod is formed in the connecting sleeve, a straight sliding slot slidably cooperating with the sliding shaft is formed in the inner wall of the lifting hole, and the bottom end of the straight sliding slot communicates with the top end of the spiral sliding slot.

[0015] Preferably, the liquid control mechanism comprises a separation plate, a first plugging assembly, and a second plugging assembly, wherein the separation plate is fixedly installed in the liquid falling cavity, the separation plate separates the bottom of the liquid falling cavity into a liquid storage cavity, a communication hole is formed in the separation plate to communicate the liquid falling cavity and the liquid storage cavity, the first plugging assembly can plug the communication hole, and the guide rod can drive the first plugging assembly to open and close the communication hole.

[0016] The bottom of the processing cylinder is provided with a liquid outlet communicating with the liquid storage cavity, the second plugging assembly can plug the liquid outlet, and the guide rod can drive the second plugging assembly to open and close the liquid outlet.

[0017] Preferably, the first plugging assembly comprises a first tapered plug and a first plugging spring, the communication hole is tapered, the large-diameter end of the communication hole is arranged upward, the first tapered plug is slidably sleeved on the guide rod, the outer periphery of the guide rod is circumferentially connected with a first boss, a first reset sliding slot slidably cooperating with the first boss is formed in the first tapered plug, and the first plugging spring is located in the first reset sliding slot and abuts against the end inner wall of the first boss and the first reset sliding slot.

[0018] Preferably, the second plugging assembly comprises a second tapered plug and a second plugging spring, the liquid outlet is tapered, and the large-diameter opening of the liquid outlet is arranged downward, the second tapered plug is slidably sleeved on the guide rod, the outer periphery of the guide rod is circumferentially connected with a second boss, a second reset sliding slot slidably cooperating with the second boss is formed in the second tapered plug, and the second plugging spring is located in the second reset sliding slot and abuts against the end inner wall of the second boss and the second reset sliding slot.

[0019] A method for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization, the operation method is as follows:

[0020] S1, seawater pretreatment;

[0021] S2, the pretreated seawater enters the falling film evaporator, the concentrated liquid generated after the evaporation of seawater drops into the liquid falling cavity, the water in the seawater is evaporated into the separator for separation again, the compressor works to compress the steam in the separator and increase the pressure and temperature of the steam, and the steam with increased pressure and temperature is transported to the heating cavity to heat the seawater in the tube bundle;

[0022] S3, the concentrated liquid in the liquid falling cavity is discharged into the evaporation groove on the evaporation disc for evaporation and crystallization;

[0023] S4, the steam in the heating cavity is transported to the evaporation disc through the heat transfer mechanism and is used for heating and evaporating the concentrated liquid in the evaporation groove;

[0024] S5, the steam in the evaporation disc is introduced into the condenser for condensation treatment.

[0025] Preferably, in S1, the pretreatment of seawater includes removal of suspended solids and colloids, sterilization and algae removal, hardness reduction, and boron removal.

[0026] The device and method for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization have the following beneficial effects: the separator, compressor, falling film evaporator, support frame, evaporation disc, heat transfer mechanism, guide rod, wall scraping mechanism and liquid control mechanism are arranged to heat and evaporate the seawater forming a liquid film, ensure the evaporation effect, use the waste heat of evaporation to evaporate seawater, save energy and protect the environment, in addition, the inner wall of the tube bundle can be cleaned to reduce the influence of fouling on the heat conduction effect of the inner wall of the tube bundle, the discharge rate of the concentrated liquid generated after evaporation can be controlled according to the crystallization condition, and the concentrated liquid is evaporated and crystallized by using the waste heat, the crystallization condition is controlled, and the steam after evaporation and crystallization is condensed into fresh water. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the overall structure schematic view of the device for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization.

[0028] Figure 2 It is the overall structure schematic view of the device for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization.

[0029] Figure 3 It is the overall structure schematic view of the device for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization.

[0030] Figure 4 It is the overall structure schematic view of the device for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization.

[0031] Figure 5 A top view of a section of a pipe bundle and a sleeve rod in a device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to the present application;

[0032] Figure 6 A structure diagram of a scraping block in a device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to the present application;

[0033] Figure 7 A lower half section view of a processing cylinder in a device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to the present application;

[0034] Figure 8 A section view of two blocking components in a device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to the present application;

[0035] Figure 9 A structure diagram of a guide rod and an ejection inclined block in a device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to the present application.

[0036] In the figure: 1, a separator; 2, a compressor; 3, a processing cylinder; 4, a first partition; 5, a second partition; 6, a pipe bundle; 7, a liquid distribution cavity; 8, a heating cavity; 9, a liquid falling cavity; 10, a support frame; 11, an evaporation disc; 12, a guide rod; 13, a membrane distributor; 14, a sleeve rod; 15, a scraping block; 16, an anti-slip block; 17, a retraction spring; 18, an ejection inclined block; 19, a connecting sleeve; 20, a sliding shaft; 21, a straight sliding groove; 22, a spiral sliding groove; 23, a separation plate; 24, a liquid storage cavity; 25, a first conical plug; 26, a first blocking spring; 27, a second conical plug; 28, a second blocking spring. DETAILED DESCRIPTION

[0037] REFERENCE Figures 1-9The application provides a device for co-production of non-edible salt and fresh water based on seawater evaporation and crystallization, which comprises a separator 1, a compressor 2 and a falling film evaporator. The falling film evaporator comprises a processing cylinder 3, a first baffle 4, a second baffle 5 and a tube bundle 6. The falling film evaporator further comprises a film distributor 13 which is fixedly installed in a liquid distribution cavity 7. The film distributor 13 is used for uniformly distributing seawater on the first baffle 4. The inner diameter of the tube bundle 6 is greater than 30 mm. The first baffle 4 and the second baffle 5 are fixedly installed in the processing cylinder 3. The first baffle 4 and the second baffle 5 divide the processing cylinder 3 into the liquid distribution cavity 7, a heating cavity 8 and a liquid falling cavity 9 which are arranged in an upper-middle-lower mode. The tube bundle 6 is located in the heating cavity 8. The two ends of the tube bundle 6 respectively penetrate through the first baffle 4 and the second baffle 5 and are communicated with the liquid distribution cavity 7 and the liquid falling cavity 9. The separator 1 is communicated with the liquid falling cavity 9. The separator 1 is communicated with the compressor 2. The compressor 2 is communicated with the heating cavity 8. Seawater is transported into the liquid distribution cavity 7 and uniformly injected into the tube bundle 6 through the film distributor 13, and a liquid film is formed on the inner wall of the tube bundle 6. A supporting frame 10 is arranged below the processing cylinder 3. An evaporation disc 11 is installed on the supporting frame 10 in a lifting mode. In addition, a supporting frame is needed to support the separator 1, the compressor 2 and the falling film evaporator. An evaporation groove is formed in the top surface of the evaporation disc 11. A heat transfer mechanism is arranged between the processing cylinder 3 and the evaporation disc 11. The heat transfer mechanism is used for transferring steam heat in the heating cavity 8 to the evaporation disc 11.After the water in the seawater is evaporated, the concentrated liquid gathers and drops into the liquid falling cavity 9, and the concentrated liquid is discharged to the evaporation groove of the evaporation disc 11 for evaporation crystallization to produce salt. The heat transfer mechanism includes pipelines and valves, and the evaporation disc 11 is internally laid with a coil pipe. The steam in the heating cavity 8 is transported to the coil pipe by the pipeline to heat the evaporation disc 11, thereby accelerating the evaporation crystallization of the concentrated liquid. In addition, the steam after waste heat utilization is cooled into fresh water by the condenser, ensuring that most of the steam is condensed into fresh water. The evaporation disc 11 is fixedly connected with a vertically arranged guide rod 12 which slidably penetrates the bottom of the processing cylinder 3 and extends into the tube bundle 6. The axis of the tube bundle 6 coincides with the axis of the guide rod 12. The tube bundle 6 is provided with a wall scraping mechanism which can scrape the inner wall of the tube bundle 6. When the guide rod 12 moves up and down, the guide rod 12 can drive the wall scraping mechanism to operate. The processing cylinder 3 is provided with a liquid control mechanism for discharging the water in the liquid falling cavity 9 to the evaporation groove. When the guide rod 12 moves up and down, the guide rod 12 can drive the liquid control mechanism to move. In actual conditions, seawater is transported into the processing cylinder 3 for heating and evaporation treatment. The water in the seawater is evaporated into the separator 1. The steam is separated again in the separator 1. The compressor 2 compresses the steam in the separator 1 to increase the temperature and pressure of the steam. The compressed steam is transported into the heating cavity 8 to heat and evaporate the liquid film in the tube bundle 6. The steam in the heating cavity 8 is transported into the evaporation disc 11 to heat and evaporate the concentrated liquid in the evaporation groove. The effect of evaporation is improved. At the same time, the guide rod 12 transmits the temperature on the evaporation disc 11 to the concentrated liquid to heat the concentrated liquid at different depths, ensuring the effect of evaporation. In addition, the discharge of the concentrated liquid is controlled by the lifting movement of the evaporation disc 11. The discharge of the concentrated liquid can be controlled according to the evaporation crystallization. In addition, when the guide rod 12 descends, the wall scraping mechanism can scrape the scale on the inner wall of the tube bundle 6, ensuring the heating and evaporation treatment of the liquid film and reducing energy consumption. The guide rod 12 can also transmit the temperature of the evaporation disc 11 to the tube bundle 6.

[0038] As Figure 3 , Figure 4 , Figure 5 and Figure 6As shown in the middle, the wall scraping mechanism includes sleeve rod 14, scraping block 15, anti-slip block 16, retraction spring 17, ejection assembly and rotation guide assembly; sleeve rod 14 is located in tube bundle 6, the position of sleeve rod 14 in tube bundle 6 cannot be lifted, and sleeve rod 14 is sleeved on guide rod 12, both sides of sleeve rod 14 are provided with receiving groove capable of accommodating scraping block 15, when scraping block 15 is accommodated in receiving groove, sleeve rod 14 and scraping block 15 form a cylinder, anti-slip block 16 is fixedly connected to the side of scraping block 15, the inner wall of receiving groove is provided with limiting sliding groove in sliding cooperation with anti-slip block 16, retraction spring 17 is located in limiting sliding groove, and both ends of retraction spring 17 are respectively connected with anti-slip block 16 and the end wall of limiting sliding groove, when guide rod 12 moves downward, scraping block 15 is pushed out of receiving groove by ejection assembly and abuts against the inner wall of tube bundle 6, when guide rod 12 moves downward, scraping block 15 is also driven to rotate by rotation guide assembly and scrapes the inner wall of tube bundle 6, in actual situation, when guide rod 12 moves downward, scraping block 15 is driven to extend out of receiving groove by ejection assembly, scraping block 15 abuts against the inner wall of tube bundle 6, guide rod 12 continues to move downward, the downward movement of guide rod 12 is converted into the rotary movement of scraping block 15 by rotation guide assembly, so that scraping block 15 scrapes the inner wall of tube bundle 6, and the scale on the inner wall of tube bundle 6 is cleaned.

[0039] As shown in Figure 4 , Figure 5 , Figure 6 and Figure 9 , the ejection assembly includes an ejection inclined block 18, which is fixedly connected to the outer periphery of the guide rod 12. The scraping block 15 is provided with a trapezoidal groove in sliding cooperation with the ejection inclined block 18. When the guide rod 12 descends, the guide rod 12 drives the ejection inclined block 18 to move downward synchronously. Since the sleeve rod 14 cannot be lifted, the inclined surface of the ejection inclined block 18 and the inclined surface of the trapezoidal groove slide to eject the scraping block 15 out of the receiving groove, so that the scraping block 15 abuts against the inner wall of the tube bundle 6.

[0040] As shown in Figure 4 , Figure 5 , Figure 6 and Figure 9As shown in the middle, the rotating guide assembly includes a connecting sleeve 19 and a sliding shaft 20; the connecting sleeve 19 is fixedly connected to the bottom surface of the film distributor 13, the top end of the sleeve rod 14 is rotatably connected to the bottom end of the connecting sleeve 19, and the sliding shaft 20 is fixedly connected to the outer periphery of the guide rod 12. A lifting hole is formed in the connecting sleeve 19 and is in sliding cooperation with the guide rod 12. A straight sliding groove 21 and a spiral sliding groove 22 are formed in the inner wall of the lifting hole and are in sliding cooperation with the sliding shaft 20. The bottom end of the straight sliding groove 21 communicates with the top end of the spiral sliding groove 22. In actual conditions, when the scraping block 15 is driven to slide out of the receiving groove, the guide rod 12 drives the sliding shaft 20 to slide in the straight sliding groove 21. When the guide rod 12 continues to descend into the spiral sliding groove 22, the sliding shaft 20 slides in the spiral sliding groove 22. The movement track of the sliding shaft 20 is spiral. The sliding shaft 20 drives the guide rod 12 to rotate synchronously. The guide rod 12 drives the sleeve rod 14 to rotate synchronously. The sleeve rod 14 drives the extended scraping block 15 to rotate synchronously, thereby achieving the wiping and cleaning of the inner wall of the tube bundle 6.

[0041] As shown in Figure 2 and Figure 7 , the liquid control mechanism includes a separation plate 23, a first blocking assembly and a second blocking assembly. The separation plate 23 is fixedly installed in the liquid falling cavity 9, and separates the bottom of the liquid falling cavity 9 into a liquid storage cavity 24. The separation plate 23 is provided with a communication hole communicating the liquid falling cavity 9 and the liquid storage cavity 24. The first blocking assembly can block the communication hole, and the guide rod 12 can drive the first blocking assembly to open and close the communication hole. The bottom of the processing cylinder 3 is provided with a liquid outlet communicating with the liquid storage cavity 24. The second blocking assembly can block the liquid outlet, and the guide rod 12 can drive the second blocking assembly to open and close the liquid outlet. In the specific operation process, the concentrated liquid drops into the liquid falling cavity 9, and the guide rod 12 is lifted to drive the first blocking assembly to open the communication hole, and the concentrated liquid in the communication hole is discharged into the liquid storage cavity 24. At this time, the second blocking assembly blocks the liquid outlet to reduce the accidental spraying of high-temperature concentrated liquid. The high-temperature concentrated liquid is discharged into the liquid storage cavity 24 for cooling treatment (30-40°C), and then the cooled concentrated liquid is discharged from the liquid outlet into the evaporation tank for evaporation and crystallization treatment. When the guide rod 12 moves downward, the communication hole is blocked, and the guide rod 12 continues to move downward. The guide rod 12 opens the second blocking assembly to discharge the cooled concentrated liquid.

[0042] As shown in Figure 2 , Figure 7 and Figure 8As shown in the figure, the first plugging assembly includes a first conical plug 25 and a first plugging spring 26; the communication hole is conical, and the large-diameter end of the communication hole is arranged upward, the first conical plug 25 is slidably sleeved on the guide rod 12, the outer periphery of the guide rod 12 is circumferentially connected with a first boss, a first reset sliding groove is formed in the first conical plug 25 and slidably matched with the first boss, the first plugging spring 26 is located in the first reset sliding groove, and the two ends of the first plugging spring 26 are respectively in abutment with the first boss and the end inner wall of the first reset sliding groove, the second plugging assembly includes a second conical plug 27 and a second plugging spring 28; the liquid outlet is conical, and the large-diameter opening of the liquid outlet is arranged downward, the second conical plug 27 is slidably sleeved on the guide rod 12, the outer periphery of the guide rod 12 is circumferentially connected with a second boss, a second reset sliding groove is formed in the second conical plug 27 and slidably matched with the second boss, the second plugging spring 28 is located in the second reset sliding groove, and the two ends of the second plugging spring 28 are respectively in abutment with the second boss and the end inner wall of the second reset sliding groove, in the specific operation, the guide rod 12 moves upward, the sliding shaft 20 slides upward in the straight sliding groove 21, the guide rod 12 drives the second boss to synchronously rise and compresses the second plugging spring 28, the guide rod 12 drives the first boss to synchronously rise, the first boss drives the first conical plug 25 to synchronously rise and open the communication hole, and the concentrated liquid is discharged into the liquid storage cavity 24, then the guide rod 12 drives the first boss and the second boss to synchronously move downward, the first conical plug 25 follows the downward movement to plug the communication hole, under the rebounding action of the second plugging spring 28, the second conical plug 27 always plugs the liquid outlet, the guide rod 12 continues to descend, drives the second conical plug 27 to descend and opens the liquid outlet, and the concentrated liquid is discharged into the evaporation tank, so that evaporation crystallization is carried out, in this process, the discharge rate of the concentrated liquid can be controlled by the descending height of the second conical plug 27, and the discharge speed of the concentrated liquid can be controlled according to the actual crystallization condition, (when the discharge rate of the concentrated liquid is controlled, the scraping block 15 will not be triggered to extend into the receiving groove).

[0043] The operation method is as follows:

[0044] S1, seawater pretreatment; suspended solids and colloidal removal, seawater first enters the flocculation sedimentation tank, and flocculants such as polyaluminum chloride (PAC) are added (the dosage is generally 5-15 mg / L), so that the suspended particles and colloidal substances in the seawater form larger flocs, which are removed by sedimentation. Subsequently, the seawater flows into a multi-medium filter, which is internally filled with quartz sand, anthracite and other filter materials, further filtering the remaining fine particles, so that the seawater turbidity is reduced to below 1 NTU, meeting the requirements of subsequent treatment; germicidal and algicidal treatment, to prevent microorganisms from breeding in the equipment and causing biofouling problems, the filtered seawater enters the ultraviolet germicidal lamp, which uses ultraviolet irradiation (dose generally 30-40 mJ / cm²) to destroy the DNA structure of microorganisms, killing bacteria, algae and other microorganisms in seawater. Some projects can also use chlorine dioxide disinfection, with a dosage of 0.5-1.5 mg / L to ensure the sterilization effect while avoiding the production of too many harmful by-products; hardness reduction and boron removal treatment, since calcium and magnesium ions (total hardness of 1.2-1.8 g / L as CaCO3) in seawater can easily cause evaporator scaling, softening treatment is needed, which can be achieved by ion exchange resin softening method. Through strong acid cation exchange resin, calcium and magnesium ions in seawater are exchanged with sodium ions on the resin, reducing the content of calcium and magnesium ions in seawater to below 50 mg / L. For boron elements (content about 5-8 mg / L), which are harmful to the human body and difficult to remove, special ion exchange resin or reverse osmosis boron removal process can be used to reduce the boron content to below 0.5 mg / L, meeting the fresh water quality requirements.

[0045] S2, the pretreated seawater enters the falling film evaporator, under the action of the film distributor 13, the seawater is uniformly distributed on the inner wall of the tube bundle 6, forming a continuous liquid film with a thickness of about 0.5-2 mm (the film distributor 13 can be a tooth slot type, spiral flow type or perforated plate type, etc., such as a tooth slot type film distributor which distributes seawater through 2-5 mm wide equal-width tooth slots), the falling film evaporator shell is connected to the secondary steam compressed by the compressor 2 as a heat source, and the seawater in the tube bundle absorbs heat to start evaporation, generating secondary steam. To ensure the stability of the evaporation process, the flow rate of the seawater should be controlled at 1.5-3 m / s, and a stable liquid level of 50-100 mm above the film distributor 13 should be maintained to form a constant water head difference. The concentrated liquid produced by the evaporation of seawater falls into the liquid falling chamber 9, and the water in the seawater is evaporated into the separator 1 for further separation. The compressor 2 works to compress and increase the pressure and temperature of the steam in the separator 1, and then the steam with increased pressure and temperature is transported to the heating chamber 8 to heat the seawater in the tube bundle 6.

[0046] S3, the concentrated liquid (salt concentration up to 25%-30%) in the liquid falling chamber 9 is discharged into the evaporation tank on the evaporation disc 11 for evaporation and crystallization;

[0047] S4, the steam in the heating cavity 8 is delivered to the evaporation disc 11 through the heat transfer mechanism and the concentrated liquid in the evaporation groove is heated and evaporated;

[0048] S5, the steam in the evaporation disc 11 is delivered to the condenser for condensation treatment.

[0049] The above is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A device for co-production of non-edible salt and fresh water based on evaporation and crystallization of seawater, characterized in that, Including separator (1), compressor (2) and falling film evaporator, the falling film evaporator includes processing cylinder (3), No. 1 baffle (4), No. 2 baffle (5) and tube bundle (6);The No. 1 baffle (4), No. 2 baffle (5) are all fixedly installed in processing cylinder (3), and No. 1 baffle (4), No. 2 baffle (5) divide processing cylinder (3) into distribution liquid cavity (7), heating cavity (8), liquid falling cavity (9) arranged in upper middle lower, the tube bundle (6) is located in heating cavity (8), both ends of the tube bundle (6) are respectively through No. 1 baffle (4), No. 2 baffle (5) and communicate distribution liquid cavity (7), liquid falling cavity (9), the separator (1) is communicated with liquid falling cavity (9), the separator (1) is communicated with compressor (2), the compressor (2) is communicated with heating cavity (8); The bottom of the processing cylinder (3) is arranged with a support frame (10), the support frame (10) is installed with an evaporation tray (11), the top surface of the evaporation tray (11) is provided with an evaporation groove, a heat transfer mechanism is arranged between the processing cylinder (3) and the evaporation tray (11), and the heat transfer mechanism is used to transfer the steam heat in the heating cavity (8) to the evaporation tray (11); The evaporation tray (11) is fixedly connected with a vertically arranged guide rod (12), the guide rod (12) slides through the bottom of the processing cylinder (3) and extends into the tube bundle (6), a wall scraping mechanism is arranged in the tube bundle (6), and the wall scraping mechanism can scrape the inner wall of the tube bundle (6); when the guide rod (12) moves up and down, the guide rod (12) can drive the wall scraping mechanism to operate; A liquid control mechanism is installed on the processing cylinder (3), the liquid control mechanism is used to discharge the water in the liquid falling cavity (9) into the evaporation groove, and when the guide rod (12) moves up and down, the guide rod (12) can drive the liquid control mechanism to move; The wall scraping mechanism includes a sleeve rod (14), a scraping block (15), an anti-slip block (16), a retraction spring (17), an ejection assembly and a rotary guide assembly; the sleeve rod (14) is located in the tube bundle (6) and cannot be lifted, and the sleeve rod (14) is sleeved on the guide rod (12), scraping blocks (15) are arranged on both sides of the sleeve rod (14), the anti-slip block (16) is fixedly connected to the side of the scraping block (15), the inner wall of the receiving groove is provided with a limiting sliding groove in sliding fit with the anti-slip block (16), and the retraction spring (17) is located in the limiting sliding groove, and the two ends of the retraction spring (17) are respectively connected with the anti-slip block (16) and the end inner wall of the limiting sliding groove; When the guide rod (12) moves downward, the scraping block (15) is pushed out of the receiving groove by the ejection assembly and abuts against the inner wall of the tube bundle (6); When the guide rod (12) continues to move downward, the scraping block (15) can also be driven to rotate by the rotary guide assembly and scrape the inner wall of the tube bundle (6). The ejection assembly comprises an ejection inclined plane block (18) fixedly connected to the outer periphery of the guide rod (12), and a trapezoidal slot is formed in the scraping block (15) to slidably cooperate with the ejection inclined plane block (18); The rotating guide assembly comprises a connecting sleeve (19) and a sliding shaft (20); the connecting sleeve (19) is fixedly connected to the bottom surface of the film distributor (13), the top end of the sleeve rod (14) is rotatably connected to the bottom end of the connecting sleeve (19), the sliding shaft (20) is fixedly connected to the outer periphery of the guide rod (12), a lifting hole is formed in the connecting sleeve (19) to slidably cooperate with the guide rod (12), and a straight-line sliding groove (21) and a spiral sliding groove (22) are formed in the inner wall of the lifting hole to slidably cooperate with the sliding shaft (20).

2. The apparatus for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to claim 1, characterized in that, The falling-film evaporator further comprises a film distributor (13) fixedly installed in the liquid distribution cavity (7), and the film distributor (13) is used for uniformly distributing seawater onto the first baffle (4).

3. A device for co-production of non-edible salt and fresh water based on evaporation and crystallization of seawater according to claim 1, characterized in that, The liquid control mechanism comprises a separation plate (23), a first blocking assembly and a second blocking assembly; the separation plate (23) is fixedly installed in the liquid falling cavity (9), the separation plate (23) separates the bottom of the liquid falling cavity (9) into a liquid storage cavity (24), a communication hole is formed in the separation plate (23) to communicate the liquid falling cavity (9) and the liquid storage cavity (24), the first blocking assembly can block the communication hole, and the guide rod (12) can drive the first blocking assembly to open and close the communication hole; The bottom of the processing cylinder (3) is provided with a liquid outlet communicating with the liquid storage cavity (24), the second blocking assembly can block the liquid outlet, and the guide rod (12) can drive the second blocking assembly to open and close the liquid outlet.

4. A device for co-production of non-edible salt and fresh water based on evaporation and crystallization of seawater according to claim 3, characterized in that, The first blocking assembly comprises a first conical plug (25) and a first blocking spring (26); the communication hole is conical, the large-diameter end of the communication hole is arranged upward, the first conical plug (25) is slidably sleeved on the guide rod (12), the outer periphery of the guide rod (12) is circumferentially connected with a first boss, a first reset sliding groove is formed in the first conical plug (25) to slidably cooperate with the first boss, and the first blocking spring (26) is located in the first reset sliding groove and abuts against the end of the first boss and the inner wall of the first reset sliding groove.

5. A device for co-production of non-edible salt and fresh water based on evaporation and crystallization of seawater according to claim 4, characterized in that, The second blocking assembly comprises a second conical plug (27) and a second blocking spring (28); the liquid outlet is conical, and the large-diameter opening of the liquid outlet is arranged downward, the second conical plug (27) is slidably sleeved on the guide rod (12), the outer periphery of the guide rod (12) is circumferentially connected with a second boss, a second reset sliding groove is formed in the second conical plug (27) to slidably cooperate with the second boss, and the second blocking spring (28) is located in the second reset sliding groove and abuts against the end of the second boss and the inner wall of the second reset sliding groove.

6. A method for co-production of non-edible salt and fresh water based on seawater evaporation crystallization, using the device for co-production of non-edible salt and fresh water based on seawater evaporation crystallization according to any one of claims 1-5, characterized in that, The operation method is as follows: S1, seawater pretreatment; S2, the pretreated seawater into falling film evaporator, seawater evaporation produced concentrated liquid drop to the liquid chamber (9) in, the water in the seawater is evaporated into the separator (1) is separated again, compressor (2) work will be compressed and the pressure and temperature of the steam in the separator (1) steam to the heating chamber (8) into the tube bundle (6) in the seawater heating treatment; S3, the concentrated liquid in the liquid chamber (9) is discharged to the evaporation tray (11) on the evaporation tank evaporation crystallization; S4, the steam in the heating chamber (8) is transported to the evaporation tray (11) by the heat transfer mechanism and the concentrated liquid in the evaporation tank is heated and evaporated; S5, the steam in the evaporation tray (11) is introduced into the condenser for condensation treatment.

7. A method for co-production of non-edible salt and fresh water based on evaporation and crystallization of seawater according to claim 6, characterized in that, In S1, the pretreatment of seawater includes removal of suspended solids and colloids, sterilization and algae removal, hardness reduction and boron removal.

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