A filtering device for solar desalination of seawater

Abstract

The present invention belongs to the technical field of seawater desalination treatment, and specifically relates to a filtering device for solar seawater desalination, including a support frame, a mounting seat, a water distribution tank, a gas collecting cylinder and a solar heat collecting tube; it further includes a salt residue filtering mechanism; the salt residue filtering mechanism is used to capture the salt residue falling from the inside of the solar heat collecting tube; the salt residue filtering mechanism includes a screw rod, a guiding frame and a filter screen; the screw rod is rotatably connected between the mounting seats; the screw rod passes through the guiding frame and is connected thereto through a screw nut pair; the filter screen is fixedly connected inside the guiding frame. The salt residue slides down along the inclined solar heat collecting tube into the water distribution tank, and the guiding frame is controlled by the salt residue filtering mechanism to reciprocate cyclically inside the water distribution tank. The filter screen is used to capture and filter the salt residue in the concentrated seawater. When the guiding frame moves, it can scrape the inner wall of the water distribution tank and remove the salt residue or other impurities adhered to its surface, improving the overall operation efficiency of the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of seawater desalination treatment, and specifically relates to a filtering device for solar seawater desalination. Background Art

[0002] With the impact of global climate change and population growth, the problem of water resource shortage is becoming increasingly serious. Especially in arid and semi-arid regions, the lack of water resources has become one of the important factors restricting economic and social development. As an effective method to solve the problem of water resource shortage, seawater desalination can not only relieve the tense situation of water resources, but also contribute to the economic development of coastal areas.

[0003] Currently, relevant technologies for solar devices for seawater desalination have emerged. For example, a patent of CN110921746A discloses a solar seawater desalination device, which includes an automatic control system, two sets of filtering systems, a wind-solar complementary power generation system, multiple sets of solar heating systems, and a negative pressure evaporation and condensation system supporting the solar heating system. The negative pressure evaporation and condensation system is connected to a fresh water collection tank through a water pipe; another example is a patent of CN103332757B, which discloses a solar seawater desalination device, on which a hot water collecting tank and solar heat collecting pipes are integrally installed. The lumen of the solar heat collecting pipe is communicated with the inner cavity of the hot water collecting tank. The hot water collecting tank is provided with a water inlet and a steam outlet communicated with its inner cavity. The water inlet is connected with a water replenishing device, and the steam outlet is communicated with a condenser. The body of the hot water collecting tank is arranged in an inclined or vertical manner, and its steam outlet end is higher than the water inlet end. Multiple solar heat collecting pipes are respectively arranged on both sides of the hot water collecting tank. A steam-water separator is connected in series between the steam outlet of the hot water collecting tank and the condenser. The steam separation port of the steam-water separator is connected to the steam inlet interface of the condenser. The water replenishing inlet and the water replenishing outlet of the water replenishing device are respectively communicated with the cooling water outlet of the condenser and the water inlet of the hot water collecting tank.

[0004] However, the above technologies often have the following defects: They use solar heat collecting pipes to heat seawater so that the water in it escapes in the form of steam, and then the steam is cooled to obtain fresh water. However, as the water evaporates and the salt is concentrated, salt slag, including sodium chloride and other salts and minerals with lower solubility, will gradually precipitate inside the solar heat collecting pipes. It is necessary to regularly stop the machine and disassemble to remove the salt slag. Otherwise, the salt slag gradually accumulates inside the solar heat collecting pipes, which is likely to cause problems such as blockage and corrosion of the equipment, and increase the heat conduction resistance, reducing the heating efficiency of the solar heat collecting pipes for seawater.

[0005] Therefore, the present invention provides a filtering device for solar seawater desalination. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art and solve at least one of the technical problems proposed in the background art.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A filtering device for solar desalination of seawater according to the present invention includes a support frame, a mounting seat, a water distribution chamber, a gas collecting cylinder, and a solar heat collecting tube;

[0008] A pair of the mounting seats are provided, and the water distribution chamber is fixedly connected between the mounting seats; A group of the solar heat collecting tubes are provided and are respectively communicated with the water distribution chamber and the gas collecting cylinder; The water distribution chamber is communicated with a water inlet pipe; The gas collecting cylinder is communicated with an air outlet pipe;

[0009] It further includes a salt residue filtering mechanism; The salt residue filtering mechanism is arranged inside the water distribution chamber; The salt residue filtering mechanism is used to capture the salt residue falling from inside the solar heat collecting tube; The salt residue filtering mechanism includes a screw rod, a guiding frame, and a filter screen;

[0010] The screw rod is rotatably connected between the mounting seats; The screw rod is driven by a motor to perform periodic forward and reverse rotations; The guiding frame is slidably matched with the inner wall of the water distribution chamber; The screw rod penetrates through the guiding frame and is connected thereto through a screw-nut pair; The filter screen is fixedly connected inside the guiding frame.

[0011] Preferably, the mounting seat and the gas collecting cylinder are respectively fixedly connected to the bottom and the top of the support frame; The solar heat collecting tubes are equidistantly and parallelly distributed and are in an inclined state; A group of connecting tubes are evenly distributed on the surface of the gas collecting cylinder; The solar heat collecting tubes are respectively inserted into the connecting tubes and are hermetically connected thereto.

[0012] Preferably, a fixing ring is fixedly connected inside the connecting tube; A movable column is slidably and hermetically fitted inside the top of the solar heat collecting tube; A compression spring is fixedly connected between the fixing ring and the movable column; A group of exhaust grooves are arranged at the bottom of the movable column; A scraping ring is fixedly connected to the bottom of the movable column; The scraping ring is mutually attached to the inner wall of the solar heat collecting tube.

[0013] Preferably, a group of the scraping rings are provided and are equidistantly distributed inside the solar heat collecting tube; Adjacent scraping rings are fixedly connected to each other through support bars.

[0014] Preferably, an extension groove, a sliding groove, and a slag discharge groove are arranged inside the mounting seat; A conveying box is slidably fitted inside the sliding groove; A tension spring is fixedly connected between the conveying box and the sliding groove; A slag outlet is arranged at the bottom of the conveying box.

[0015] Preferably, the inner wall of the bottom of the conveying box is inclined towards the slag outlet.

[0016] Preferably, an elastic sealing film is fixedly connected between the top of the conveying box and the sliding groove at a position above the tension spring.

[0017] Preferably, a sealing piece is provided at the bottom of the slag outlet; one end of the sealing piece away from the slag discharge groove is hinged to the conveying box, and a torsion spring is provided at the hinge.

[0018] Preferably, the bottom of the slag discharge groove is inclined towards the outside of the mounting seat; a magnetic piece is fixedly connected to the bottom of the slag discharge groove; the magnetic piece and the sealing piece attract each other when they are close.

[0019] Preferably, the filter screen is elastic, and a connecting rod is fixedly connected through the inside thereof; a group of elastic rings are evenly distributed at both ends of the connecting rod; a connecting hole is provided at the side wall of the extension groove; and a damping ring is fixedly connected inside the connecting hole.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. For the filtering device for solar seawater desalination described in the present invention, as the seawater gradually evaporates, the dissolved salts or other impurities in the seawater precipitate solid salt slag inside the solar heat collecting tube. Then, the salt slag slides down along the inclined solar heat collecting tube into the water distribution bin. By setting up the salt slag filtering mechanism, the motor drives the screw to rotate forward and reverse periodically, controlling the guiding frame to reciprocate cyclically inside the water distribution bin. Thus, the filter screen is used to capture and filter the salt slag in the concentrated seawater. At the same time, the filter screen can also filter the fresh seawater entering the water distribution bin through the water inlet pipe to remove the impurities therein, reducing the risk of equipment scaling and blockage. In addition, when the guiding frame moves, it can scrape the inner wall of the water distribution bin and remove the salt slag or other impurities adhered to its surface, improving the overall operation efficiency of the equipment.

[0022] 2. For the filtering device for solar seawater desalination described in the present invention, as the seawater inside the solar heat collecting tube is gradually vaporized by heating, the formed water vapor causes the pressure inside the heat collecting tube to increase, and pushes the movable column upward to move. The water vapor in the heat collecting tube enters the gas collecting pipe through the exhaust groove and the gap between the movable column and the connecting pipe. After the pressure is released, the compression spring pushes the movable column to reset downward. By repeating the above operations, the movable column reciprocates inside the heat collecting tube. The movable column drives a plurality of scraping rings to rub the inner wall of the solar heat collecting tube through the support bars, separating the salt slag or other impurities from the inner wall surface of the heat collecting tube, preventing the salt slag from adhering to form a heat insulation layer and reducing the heat conduction efficiency, promoting the salt slag to slide down to the water distribution bin under the action of gravity, and improving the collection efficiency of the salt slag.

[0023] 3. For the filtering device used in solar seawater desalination according to the present invention, when the motor controls the guiding frame to move to the mounting seats at both ends of the water distribution chamber, the guiding frame enters the extension groove. Then, the salt slag or other impurities captured on one side of the guiding frame and the filter screen can fall into the conveying box under the action of gravity. At the same time, the bottom of the guiding frame pushes the conveying box to move inside the sliding groove, prompting the conveying box to carry the salt slag and move outward from the mounting seat. When the slag discharge port of the conveying box aligns with the slag discharge groove, the salt slag in the conveying box automatically discharges outward through the slag discharge port and the slag discharge groove. When the subsequent guiding frame disengages from the extension groove, the tension spring drives the conveying box to reset inside the sliding groove. Through this structure, the salt slag inside the water distribution chamber can be gradually discharged out of the system, completely avoiding the adverse effects caused by the precipitated salt on the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 is the three-dimensional view of the whole of the present invention;

[0026] Figure 2 is the structural schematic diagram of the salt slag filtering mechanism in the present invention;

[0027] Figure 3 is the structural schematic diagram of the solar heat collecting tube in the present invention;

[0028] Figure 4 is Figure 3 the partial enlarged view at A in

[0029] Figure 5 is the structural schematic diagram of the movable column in the present invention;

[0030] Figure 6 is the front view of the whole of the present invention;

[0031] Figure 7 is the cross-sectional view of the mounting seat and the water distribution chamber in the present invention;

[0032] Figure 8 is Figure 7 the partial enlarged view at B in

[0033] Figure 9 is Figure 7 the partial enlarged view at C in

[0034] In the figure: support frame 1, mounting seat 2, water distribution bin 3, air collection cylinder 4, solar heat collector tube 5, water inlet pipe 6, air outlet pipe 7, screw 8, guiding frame 9, filter screen 10, motor 11, connecting pipe 12, fixing ring 13, movable column 14, compression spring 15, exhaust groove 16, scraping ring 17, support bar 18, extension groove 19, sliding groove 20, slag discharge groove 21, conveying box 22, tension spring 23, slag outlet 24, elastic sealing film 25, blocking piece 26, magnetic piece 27, connecting rod 28, elastic ring 29, connecting hole 30, damping ring 31. Detailed implementation manners

[0035] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation manners.

[0036] As Figures 1 to 9 shown, a filtering device for solar seawater desalination according to the present invention includes a support frame 1, a mounting seat 2, a water distribution bin 3, an air collection cylinder 4 and a solar heat collector tube 5;

[0037] A pair of the mounting seats 2 are provided, and the water distribution bin 3 is fixedly connected between the mounting seats 2; A group of the solar heat collector tubes 5 are provided and are respectively communicated with the water distribution bin 3 and the air collection cylinder 4; The water distribution bin 3 is communicated with a water inlet pipe 6, and a one-way valve is arranged inside the water inlet pipe 6; The air collection cylinder 4 is communicated with an air outlet pipe 7;

[0038] It further includes a salt slag filtering mechanism; The salt slag filtering mechanism is arranged inside the water distribution bin 3; The salt slag filtering mechanism is used to capture the salt slag falling from inside the solar heat collector tube 5; The salt slag filtering mechanism includes a screw 8, a guiding frame 9 and a filter screen 10;

[0039] The screw 8 is rotatably connected between the mounting seats 2; The screw 8 is driven by a motor 11 to perform periodic forward and reverse rotations; The guiding frame 9 is slidably matched with the inner wall of the water distribution bin 3; The screw 8 penetrates through the guiding frame 9 and is connected thereto through a lead screw nut pair; The filter screen 10 is fixedly connected inside the guiding frame 9.

[0040] The mounting seat 2 and the air collection cylinder 4 are respectively fixedly connected to the bottom and top of the support frame 1; The solar heat collector tubes 5 are equidistantly and parallelly distributed and are in an inclined state; A group of connecting pipes 12 are evenly distributed on the surface of the air collection cylinder 4; The solar heat collector tubes 5 are respectively inserted into the connecting pipes 12 and are hermetically connected thereto.

[0041] The prior art uses a solar heat collecting tube 5 to heat seawater so that the water therein escapes in the form of steam, and then the steam is cooled to obtain fresh water. However, as the water evaporates and the salt is concentrated, salt slag, including sodium chloride and other salts and minerals with lower solubility, will gradually precipitate inside the solar heat collecting tube 5. It is necessary to regularly stop the machine and disassemble to remove the salt slag. Otherwise, the salt slag will gradually accumulate inside the solar heat collecting tube 5, which is likely to cause problems such as blockage and corrosion of the equipment, increase the heat conduction resistance, and reduce the heating efficiency of the solar heat collecting tube 5 for seawater.

[0042] In the present invention, seawater is injected into the water distribution chamber 3 through the water inlet pipe 6. The seawater flows into a plurality of solar heat collecting tubes 5 along the water distribution chamber 3, and the water surface height is lower than the gas collecting pipe, so that the inside of the gas collecting pipe remains unobstructed. The solar heat collecting tube 5 converts light energy into heat energy to heat the seawater therein. The seawater gradually evaporates to form steam, and the steam rises along the solar heat collecting tube 5 into the inside of the gas collecting pipe and is exported outward through the air outlet pipe 7. The air outlet pipe 7 is connected to a condensing device for converting the steam into fresh water.

[0043] As the evaporation of seawater gradually proceeds, the dissolved salts or other impurities in the seawater precipitate into solid salt slag inside the solar heat collecting tube 5. Then, the salt slag slides down along the inclined solar heat collecting tube 5 into the water distribution chamber 3. By setting up a salt slag filtering mechanism, the motor 11 drives the screw rod 8 to rotate forward and reverse periodically, controlling the guiding frame 9 to reciprocate cyclically inside the water distribution chamber 3, so as to use the filter screen 10 to capture and filter the salt slag in the concentrated seawater. At the same time, the filter screen 10 can also filter the fresh seawater entering the water distribution chamber 3 through the water inlet pipe 6 to remove the impurities therein, reducing the risk of equipment scaling and blockage. In addition, when the guiding frame 9 moves, it can scrape the inner wall of the water distribution chamber 3 and remove the salt slag or other impurities adhering to its surface, improving the overall operation efficiency of the equipment.

[0044] As another embodiment of the present invention, a fixing ring 13 is fixedly connected inside the connecting pipe 12; an activity column 14 is slidably and sealingly fitted inside the top of the solar heat collecting tube 5; a compression spring 15 is fixedly connected between the fixing ring 13 and the activity column 14; a group of exhaust grooves 16 are arranged at the bottom of the activity column 14; a scraping ring 17 is fixedly connected to the bottom of the activity column 14; the scraping ring 17 is in mutual fit with the inner wall of the solar heat collecting tube 5.

[0045] A group of the scraping rings 17 are provided and are equidistantly distributed inside the solar heat collecting tube 5; adjacent scraping rings 17 are fixedly connected to each other through a support bar 18.

[0046] Since the movable column 14 blocks the top of the solar heat collector tube 5, the connecting pipe 12 and the solar heat collector tube 5 are isolated from each other in the initial state. As the seawater inside the solar heat collector tube 5 is heated and gradually vaporized, the formed water vapor causes the pressure inside the collector tube to increase, and pushes the movable column 14 upward. When the exhaust slot 16 at the bottom of the movable column 14 exposes from the end of the solar heat collector tube 5, the connecting pipe 12 and the collector tube are in a communicating state at this time. The water vapor in the collector tube enters the gas collecting pipe through the exhaust slot 16 and the gap between the movable column 14 and the connecting pipe 12. After the pressure is released, the compression spring 15 pushes the movable column 14 downward to reset and block the top of the solar heat collector tube 5 again. This structure makes the movable column 14 reciprocate inside the collector tube by repeating the above operations. The movable column 14 drives a plurality of scraping rings 17 through the support bars 18 to rub the inner wall of the solar heat collector tube 5, so as to separate salt slag or other impurities from the inner wall surface of the collector tube, prevent the salt slag from adhering to generate a heat insulation layer and reduce the heat conduction efficiency, promote the salt slag to slide down to the water distribution bin 3 under the action of gravity, and improve the collection efficiency of the salt slag.

[0047] As another embodiment of the present invention, an extension slot 19, a sliding slot 20 and a slag discharge slot 21 are arranged inside the mounting seat 2; the extension slot 19, the sliding slot 20 and the slag discharge slot 21 are sequentially communicated with each other, the extension slot 19 is aligned with the water distribution bin 3, the sliding slot 20 is located at the bottom of the extension slot 19, and the slag discharge slot 21 is located at the bottom of the sliding slot 20; a conveying box 22 is slidably fitted inside the sliding slot 20, and the top of the conveying box 22 is slightly higher than the inner wall of the water distribution bin 3; a tension spring 23 is fixedly connected between the conveying box 22 and the sliding slot 20; a slag outlet 24 is arranged at the bottom of the conveying box 22.

[0048] When the motor 11 controls the guiding frame 9 to move to the mounting seats 2 at both ends of the water distribution bin 3, the guiding frame 9 enters the extension slot 19, then the salt slag or other impurities captured by the guiding frame 9 and one side of the filter screen 10 can fall into the conveying box 22 under the action of gravity. At the same time, the bottom of the guiding frame 9 pushes the conveying box 22 to move inside the sliding slot 20, so that the conveying box 22 carries the salt slag and moves out of the mounting seat 2. When the slag outlet 24 of the conveying box 22 is aligned with the slag discharge slot 21, the salt slag in the conveying box 22 automatically discharges outward through the slag outlet 24 and the slag discharge slot 21. When the subsequent guiding frame 9 disengages from the extension slot 19, the tension spring 23 drives the conveying box 22 to reset inside the sliding slot 20. Through this structure, the salt slag inside the water distribution bin 3 can be gradually discharged out of the system, completely avoiding the adverse effects of the precipitated salt on the equipment, and the produced salt slag contains a large amount of table salt, and the table salt product can be extracted after further separation.

[0049] It should be noted that when the conveying box 22 collects salt slag, it will inevitably enter the concentrated seawater, and then the seawater will leak out together with the salt slag. Since the salt concentration of this part of the discharged seawater is relatively high and the leakage amount is small, the impact on the seawater desalination process is very small and can be ignored.

[0050] The inner wall of the bottom of the conveying box 22 is inclined towards the slag outlet 24, so that the salt slag inside the conveying box 22 can move along the inclined surface of the bottom towards the slag outlet 24 to fully discharge the salt slag outwards.

[0051] As another embodiment of the present invention, an elastic sealing film 25 is fixedly connected between the top of the conveying box 22 and the sliding groove 20, above the tension spring 23. By providing the elastic sealing film 25, when the conveying box 22 reciprocates inside the sliding groove 20, the elastic sealing film 25 can be pulled and deformed, so that the gap between the conveying box 22 and the sliding groove 20 is always in a sealed and isolated state, preventing salt slag from entering the gap and affecting the normal movement of the conveying box 22.

[0052] As another embodiment of the present invention, a blocking piece 26 is provided at the bottom of the slag outlet 24; one end of the blocking piece 26 away from the slag discharge groove 21 is hinged to the conveying box 22, and a torsion spring is provided at the hinge. Since the conveying box 22 moves towards the outside of the mounting seat 2, there must be a period of time during which the top of the conveying box 22 communicates with the extension groove 19, and the bottom of the conveying box 22 communicates with the slag discharge groove 21 through the slag outlet 24, resulting in the extension groove 19 and the slag discharge groove 21 being able to communicate with each other through the conveying box 22 and the slag outlet 24. Therefore, the seawater in the water distribution bin 3 is likely to leak out continuously. By providing the blocking piece 26, under normal circumstances, the slag outlet 24 is in a blocked state. As the conveying box 22 moves towards the slag discharge groove 21, only when the slag outlet 24 and the blocking piece 26 are completely exposed in the slag discharge groove 21, the blocking piece 26 will deflect downward under the action of the torsion spring and open the slag outlet 24 to release the salt slag. At this time, the side of the conveying box 22 close to the tension spring 23 is already flush with the side wall of the extension groove 19, and the top of the conveying box 22 no longer communicates with the extension groove 19, and the two are in an isolated state. Therefore, the seawater in the water distribution bin 3 cannot continuously discharge outwards through the conveying box 22, thereby reducing the seawater leakage phenomenon during the slag discharge process.

[0053] The bottom of the slag discharge groove 21 is inclined towards the outside of the mounting seat 2; a magnetic sheet 27 is fixedly connected to the bottom of the slag discharge groove 21; the magnetic sheet 27 attracts each other when approaching the blocking piece 26. When the slag outlet 24 and the blocking piece 26 are completely exposed in the slag discharge groove 21, the magnetic attraction of the magnetic sheet 27 on the blocking piece 26 and the restoring force of the torsion spring act together to promote the blocking piece 26 to deflect downward, improving the opening efficiency of the slag outlet 24 and preventing the blocking piece 26 from adhering to the inside of the slag outlet 24 under the viscous action of the concentrated seawater.

[0054] As another embodiment of the present invention, the filter screen 10 is elastic, and a connecting rod 28 is fixedly connected thereto; a group of elastic rings 29 are evenly distributed at both ends of the connecting rod 28; a connecting hole 30 is provided on the side wall of the extension groove 19; a damping ring 31 is fixedly connected to the inside of the connecting hole 30, and the inner diameter of the damping ring 31 is larger than the diameter of the connecting rod 28 and smaller than the outer diameter of the elastic ring 29.

[0055] During the movement of the guide frame 9 into the extension slot 19, the coupling rod 28 is inserted into the coupling hole 30, and then the elastic ring 29 on the surface of the coupling rod 28 is blocked by the damping ring 31, which causes the coupling rod 28 and the filter screen 10 to move backward relative to the guide frame 9 ( Figure 7 The filter 10 moves in the left direction, causing the filter 10 to bend and deform and accumulate force. Then the damping ring 31 squeezes and deforms the elastic ring 29 and passes over the elastic ring 29. At this time, the filter 10 shakes forward under its own elastic force ( Figure 7 Right direction), and then multiple elastic rings 29 pass through the inside of the damping ring 31 in turn, which can prompt the filter screen 10 to shake the salt residue adhered to its surface into the inside of the conveying box 22, so that the salt residue is fully separated from the filter screen 10, and further improve the transfer and discharge efficiency of the salt residue in the equipment.

[0056] The above-mentioned front, back, left, right, up and down are all based on the Figure 1 As a benchmark, according to the person's observation perspective, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0057] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0058] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A filtering device for solar desalination of seawater, comprising a support frame (1), a mounting seat (2), a water distribution tank (3), a gas collecting cylinder (4) and a solar heat collecting tube (5); There are a pair of mounting seats (2), and the water distribution tank (3) is fixedly connected between the mounting seats (2); There is a group of solar heat collecting tubes (5) which are respectively communicated with the water distribution tank (3) and the gas collecting cylinder (4); The water distribution tank (3) is communicated with a water inlet pipe (6); The gas collecting cylinder (4) is communicated with an air outlet pipe (7); It is characterized in that: It further includes a salt residue filtering mechanism; The salt residue filtering mechanism is arranged inside the water distribution tank (3); The salt residue filtering mechanism is used to capture the salt residue falling from inside the solar heat collecting tube (5); The salt residue filtering mechanism includes a screw rod (8), a guiding frame (9) and a filter screen (10); The screw rod (8) is rotatably connected between the mounting seats (2); The screw rod (8) is driven by a motor (11) to perform periodic forward and reverse rotations; The guiding frame (9) is slidably matched with the inner wall of the water distribution tank (3); The screw rod (8) passes through the guiding frame (9) and is connected to it through a screw-nut pair; The filter screen (10) is fixedly connected inside the guiding frame (9); The mounting seat (2) and the gas collecting cylinder (4) are respectively fixedly connected to the bottom and top of the support frame (1); The solar heat collecting tubes (5) are equidistantly and parallelly distributed and are in an inclined state; A group of connecting pipes (12) are evenly distributed on the surface of the gas collecting cylinder (4); The solar heat collecting tubes (5) are respectively inserted into the connecting pipes (12) and are hermetically connected to them; A fixing ring (13) is fixedly connected inside the connecting pipe (12); A movable column (14) is slidably and hermetically matched inside the top of the solar heat collecting tube (5); A compression spring (15) is fixedly connected between the fixing ring (13) and the movable column (14); A group of exhaust grooves (16) are arranged at the bottom of the movable column (14); A scraping ring (17) is fixedly connected to the bottom of the movable column (14); The scraping ring (17) is in mutual contact with the inner wall of the solar heat collecting tube (5); An extension groove (19), a sliding groove (20) and a slag discharge groove (21) are arranged inside the mounting seat (2); A conveying box (22) is slidably and hermetically matched inside the sliding groove (20); A tension spring (23) is fixedly connected between the conveying box (22) and the sliding groove (20); A slag outlet (24) is arranged at the bottom of the conveying box (22).

2. A filtering device for solar seawater desalination according to claim 1, characterized in that: There is a group of scraping rings (17) which are equidistantly distributed inside the solar heat collecting tube (5); Adjacent scraping rings (17) are fixedly connected to each other through a support bar (18).

3. A filtering device for solar seawater desalination according to claim 1, characterized in that: The inner wall of the bottom of the conveying box (22) is inclined towards the slag outlet (24).

4. A filtering device for solar seawater desalination according to claim 1, characterized in that: An elastic sealing film (25) is fixedly connected between the top of the conveying box (22) and the sliding groove (20) at a position above the tension spring (23).

5. A filtering device for solar seawater desalination according to claim 1, characterized in that: A blocking piece (26) is arranged at the bottom of the slag outlet (24); One end of the blocking piece (26) away from the slag discharge groove (21) is hinged to the conveying box (22), and a torsion spring is arranged at the hinge.

6. A filtering device for solar desalination according to claim 5, characterized in that: The bottom of the slag discharge groove (21) is inclined towards the outside of the mounting seat (2); A magnetic piece (27) is fixedly connected to the bottom of the slag discharge groove (21); The magnetic piece (27) and the blocking piece (26) attract each other when they are close.

7. A filtering device for solar seawater desalination according to claim 1, characterized in that: The filter screen (10) is elastic, and a coupling rod (28) is fixedly connected through its interior; a group of elastic rings (29) are evenly distributed at both ends of the coupling rod (28); a coupling hole (30) is provided at the side wall of the extension groove (19); a damping ring (31) is fixedly connected inside the coupling hole (30).

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