A self-cleaning composite sand filter tube

Abstract

The invention relates to the technical field of oil production and discloses a self-cleaning composite sand filter tube, which has self-cleaning ability and can reduce the blockage of sand and gravel impurities during oil production; the self-cleaning composite sand filter tube comprises a mounting frame, a rotating assembly, an outer filter screen, an inner filter screen, a driving assembly, a brush roller and a material layer; the outer filter screen and the inner filter screen are connected in the mounting frame through the rotating assembly, and the rotating assembly is connected to the driving assembly arranged at the top of the inner part of the mounting frame, so that the outer filter screen and the inner filter screen are linked to rotate after the driving assembly is impacted by crude oil; a brush roller is vertically arranged in the mounting frame, and the brush roller is placed between the outer filter screen and the inner filter screen and contacts the two; and a material layer is arranged on the outer surface of the outer filter screen, and the material layer solidifies on the outer surface of the outer filter screen at a certain temperature to close the filter holes of the outer filter screen, and melts on the outer surface of the outer filter screen at a certain temperature to open the filter holes of the outer filter screen; the sand filter tube of the invention has strong self-cleaning ability and good anti-blocking effect.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum extraction, in particular to a self-cleaning composite sand filter pipe. Background Art

[0002] During the oil extraction process, the oil in the well is often mixed with gravel impurities. Therefore, the sand-containing oil must be desanded before subsequent processing, otherwise it will affect the subsequent processing and use of the oil. The sand filter tube is one of the indispensable components in the oil extraction process. It is used to prevent the gravel impurities in the crude oil from entering the oil pump and causing damage to the oil pump. It has the advantages of simple structure and low cost, but it also has the disadvantage of being blocked by gravel impurities.

[0003] To this end, Chinese patent CN204200193U proposes a self-cleaning sand control pipe. The patent sets a propeller self-cleaning mechanism so that during the oil pumping process, the crude oil impacts the propeller and drives the brush head to rotate around the axis of the sand control pipe body, thereby removing the sand and gravel impurities attached to the filter net.

[0004] But the clogging problem of the sand filter tube occurs in two stages:

[0005] One is that during the process of going down the well, the gravel impurities in the well will adhere to the outer surface of the sand filter tube and block the filter holes of the sand filter tube. The above patent does not have a self-cleaning design for the sand filter tube during the process of going down the well, and there is a risk that the gravel impurities attached to the outer surface of the sand filter tube will enter the sand filter tube and cause blockage;

[0006] Secondly, during the oil production process, the gravel impurities in the oil adhere to the outer surface of the sand filter tube or get clogged inside it as the oil flows in. However, the above patent can only achieve self-cleaning of the outer surface of the sand filter tube, and cannot effectively clean the gravel impurities that have entered the sand filter tube. The sand filter tube still has a high risk of clogging;

[0007] Moreover, the filtering structure in the above patent is a single-layer setting, which has a major defect. Once the gravel impurities break through the single-layer filtering structure, they will enter the oil pump along with the crude oil and cause damage to the oil pump. The safety performance needs to be improved. Summary of the invention

[0008] The purpose of the present invention is to solve the problems raised in the above background technology, and then propose a self-cleaning composite sand filter tube.

[0009] The technical solution adopted by the present invention to solve the technical problem is:

[0010] A self-cleaning composite sand filter tube comprises a mounting frame, a rotating assembly, an outer filter screen, an inner filter screen, a driving assembly, a brush roller and a material layer; the mounting frame is open at the top for connection with an oil pump pipe and closed at the bottom; an outer filter screen with a circular structure and an inner filter screen coaxial with the outer filter screen are connected in the mounting frame through the rotating assembly, and the rotating assembly is connected to a driving assembly arranged at the top of the mounting frame, so that the outer filter screen and the inner filter screen are linked to rotate after the driving assembly is impacted by crude oil; a brush roller is vertically arranged in the mounting frame, the brush roller is placed between the outer filter screen and the inner filter screen and contacts the two, so that when the outer filter screen and the inner filter screen are in a rotating state, the rotating outer filter screen and the inner filter screen contact the brush roller and perform a self-cleaning action; and a material layer is arranged on the outer surface of the outer filter screen, the material layer solidifies on the outer surface of the outer filter screen at a certain temperature to close the filter holes of the outer filter screen, and melts on the outer surface of the outer filter screen at a certain temperature to open the filter holes of the outer filter screen.

[0011] The present invention further comprises an upper connecting plate, a butt tube, support rods, a lower connecting plate, a connecting pipe and a sealing cover; the upper connecting plate is in a circular structure and its middle portion is connected to the butt tube, the bottom of the upper connecting plate is connected to the lower connecting plate in a circular structure by at least four support rods, and the middle portion of the lower connecting plate is connected to the connecting pipe, the connecting pipe and the butt tube are coaxially arranged and a sealing cover is installed on the connecting pipe.

[0012] The present invention further comprises two coaxial upper annular grooves at the bottom of the upper connecting plate, a lower annular groove having the same size as the upper annular groove and corresponding to the upper annular groove is formed at the top of the lower connecting plate, and rotating components are installed in the upper annular groove and the lower annular groove.

[0013] The present invention further provides that the rotating assembly includes mounting grooves, balls, swivels and connecting plates; there are four mounting grooves which are respectively mounted in two upper annular grooves and two lower annular grooves, and a plurality of balls are mounted along the bottom and sides of the mounting grooves to form a rolling channel for mounting the swivels in the mounting groove bodies, the two swivels at the upper ends are connected by a connecting plate, the outer filter is arranged between the two swivels corresponding to each other on the upper and lower sides of the outer sides, the inner filter is arranged between the two swivels corresponding to each other on the upper and lower sides of the inner sides, and the swivel on the upper inner side is connected to the driving assembly.

[0014] The present invention further comprises a driving assembly including a horizontal frame, a rotating rod, a propeller and a connecting frame; the horizontal frame is arranged in the docking tube and its bottom is rotatably connected to the rotating rod, the rotating rod is provided with a propeller and a connecting frame located below the propeller and used to be connected to a rotating ring located on the inner upper side.

[0015] Furthermore, the present invention provides that the propeller is placed in the butt joint to enhance the impact effect of the crude oil, and the crude oil is gathered at the butt joint to form a thrust for driving the propeller to rotate.

[0016] Furthermore, the present invention adopts a filter screen structure for the horizontal frame and the connecting frame, so as to maintain normal operation and also have a filtering function to reduce the entry of gravel impurities into the oil pump and cause damage to the oil pump.

[0017] The present invention further provides two groups of brush rollers arranged circumferentially, the brush rollers are cylindrical and the bottom ends of the roller bodies are connected to the lower connecting plate, the top ends of the roller bodies are below the connecting plate, and the brush bodies are in contact with the outer filter screen and the inner filter screen.

[0018] In the present invention, the material layer is one of polyethylene wax and EVA wax.

[0019] The present invention further comprises a threaded hole corresponding to the brush roller, the bottom end of the brush roller is connected to an insertion rod, the insertion rod is inserted into the threaded hole, and the bottom end of the insertion rod is connected to a bolt, and the end of the bolt is threadedly connected to the threaded hole, so that when the bolt is in a loosened state, the brush roller can be rotated by operating the bolt.

[0020] The present invention further comprises two arc-shaped slag discharge ports symmetrically arranged on the lower connecting plate, and the slag discharge ports are located between the two lower annular grooves and a slag discharge assembly is installed in the two slag discharge ports; the slag discharge assembly can remove and process the sand and gravel impurities generated after cleaning the outer filter screen and the inner filter screen.

[0021] The present invention further provides that the slag discharge assembly comprises a slag guiding bucket, a slag discharge trough and a mounting plate; there are two slag guiding buckets and they are wide at the top and narrow at the bottom; the two slag guiding buckets are open at the top and bottom and are respectively fixed above the two slag discharge ports; two brush rollers are arranged between the two slag guiding buckets; a slag discharge trough is respectively arranged below the two slag guiding buckets; the two slag discharge troughs are respectively inserted into the two slag discharge ports for collecting sand and gravel impurities in the two slag guiding buckets; the bottoms of the two slag discharge troughs are commonly connected to a mounting plate; a center hole is opened in the middle of the mounting plate to be sleeved on the outside of the connecting pipe; and the mounting plate is pressed and fixed by a sealing cover.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention proposes a self-cleaning composite sand filter tube. Through the composite design of the outer filter screen, the inner filter screen and the material layer, the sand filter tube has multiple filtering effects and can block and filter the gravel impurities step by step. In the process of going down the well, since the temperature in the well is lower than the temperature of the material layer, the material layer solidifies on the outer surface of the outer filter screen to block the gravel impurities. As the well goes deeper, the temperature in the well gradually rises. When the temperature reaches the melting point of the material layer, the material layer melts and the filter holes of the outer filter screen open, which does not affect the subsequent absorption and filtration of crude oil.

[0024] 2. The present invention proposes a self-cleaning composite sand filter tube, which can provide a continuous filtering effect by making the rotating outer filter screen and the inner filter screen contact with the brush roller, and complete the self-cleaning operation of the outer filter screen and the inner filter screen. When the crude oil passes through the outer filter screen and the inner filter screen, the rotating action enables the entire filtering surface of the outer filter screen and the inner filter screen to be evenly contacted with the crude oil, thereby improving the filtering efficiency. Under the action of the centrifugal force generated by the rotation, a vortex is formed, reducing the risk of local wear and blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a self-cleaning composite sand filter tube;

[0026] Figure 2 for Figure 1 A is a partial enlarged schematic diagram;

[0027] Figure 3 for Figure 1 A partial enlarged schematic diagram of B in the middle;

[0028] Figure 4 It is a structural schematic diagram of the upper connecting plate;

[0029] Figure 5 It is a schematic diagram of the installation position of the ball on the installation groove;

[0030] Figure 6 is a schematic diagram of the structure of the swivel;

[0031] Figure 7 It is a structural schematic diagram of a brush roller;

[0032] Figure 8 The figure is a schematic diagram of the installation position of the plug rod and the bolt;

[0033] Fig. 9 for Figure 8 A partial enlarged schematic diagram of C in the middle;

[0034] Fig.10 This is a schematic diagram of the installation position of the slag discharge component;

[0035] Fig.11 for Fig.10 A partial enlarged schematic diagram of D in the middle;

[0036] Fig.12 It is a schematic diagram of the structural position of the slag discharge port;

[0037] Fig.13 This is a schematic diagram of the installation position of the slag discharge trough on the installation plate;

[0038] Among them: 1. Installation frame; 11. Upper connecting plate; 111. Upper annular groove; 12. Butt pipe; 13. Support rod; 14. Lower connecting plate; 141. Lower annular groove; 142. Threaded hole; 143. Slag discharge port; 15. Connecting pipe; 16. Sealing cover; 2. Rotating assembly; 21. Mounting groove; 22. Ball bearing; 23. Swivel; 24. Connecting plate; 3. Outer filter; 31. Inner filter; 4. Driving assembly; 41. Horizontal frame; 42. Rotating rod; 43. Propeller; 44. Connecting frame; 5. Brush roller; 51. Insert rod; 52. Bolt; 6. Material layer; 7. Slag discharge assembly; 71. Slag hopper; 72. Slag discharge groove; 73. Mounting plate; 731. Center hole. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is further described in combination with the drawings and embodiments:

[0040] Refer to the attached Figure 1 As shown, a self-cleaning composite sand filter tube includes a mounting frame 1, a rotating assembly 2, an outer filter screen 3, an inner filter screen 31, a driving assembly 4, a brush roller 5 and a material layer 6.

[0041] The mounting frame 1 plays a role in mounting and fixing, and has an open top and a closed bottom structure. In this embodiment, the mounting frame 1 adopts a frame structure to reduce the deadweight of the sand filter pipe, and the open top end is used to connect with the oil pump pipe.

[0042] An outer filter screen 3 with a circular structure and an inner filter screen 31 coaxial with the outer filter screen 3 are connected in the mounting frame 1 through a rotating assembly 2, and the rotating assembly 2 is connected to a driving assembly 4 arranged at the top of the mounting frame 1, so that the outer filter screen 3 and the inner filter screen 31 are rotated in conjunction after the driving assembly 4 is impacted by the crude oil; in this embodiment, the outer filter screen 3 and the inner filter screen 31 in a rotating state jointly block and filter the gravel impurities in the crude oil, which has the following multiple protection functions:

[0043] For example, the outer filter 3 and the inner filter 31 have a dual filtering effect, and can block and filter sand and gravel impurities step by step; for example, the outer filter 3 and the inner filter 31 in a rotating state can provide a continuous filtering effect. When the crude oil passes through the outer filter 3 and the inner filter 31, the rotating action enables the entire filtering surface of the outer filter 3 and the inner filter 31 to be evenly in contact with the crude oil, thereby improving the filtering efficiency, and under the action of the centrifugal force generated by the rotation, a vortex is formed, reducing the risk of local wear and blockage; in addition, the outer filter 3 and the inner filter in a rotating state also have other advantages and functions not mentioned in the present invention, and the present invention will not go into details about this.

[0044] A brush roller 5 is vertically arranged in the mounting frame 1, and the brush roller 5 is placed between the outer filter screen 3 and the inner filter screen 31 and contacts with the two, so that when the outer filter screen 3 and the inner filter screen 31 are in a rotating state, the outer filter screen 3 and the inner filter screen 31 in the rotating state contact with the brush roller 5 and perform a self-cleaning action; in this embodiment, the brush roller 5 in a stationary state contacts with the outer filter screen 3 and the inner filter screen 31 in the rotating state, and as the outer filter screen 3 and the inner filter screen 31 rotate in contact, the brush roller 5 is able to evenly contact the filtering surfaces of the two, and then can brush off the gravel impurities attached to the filtering surfaces of the two, prevent the filter holes of the outer filter screen 3 and the inner filter screen 31 from being blocked, and maintain the stability of the filtering effect.

[0045] In addition, a material layer 6 is provided on the outer surface of the outer filter screen 3. The material layer 6 solidifies on the outer surface of the outer filter screen 3 at a certain temperature to close the filter holes of the outer filter screen 3, and melts on the outer surface of the outer filter screen 3 at a certain temperature to open the filter holes of the outer filter screen 3. In this embodiment, the temperature in the well is relatively high during oil production. From this perspective, according to the oil production environment of the technicians in this field, the material layer 6 is polyethylene wax (melting temperature is 102-115°) or EVA wax (melting temperature is 93-100°). The selection of the specific material layer 6 is not limited by the present invention and can be determined according to the actual oil production environment of the technicians in this field. When the outer filter screen 3 provided with the material layer 6 is in the process of going down the well, since the temperature in the well is lower than the temperature of the material layer 6, the material layer 6 solidifies on the outer surface of the outer filter screen 3 to block the gravel impurities. As the well goes deeper, the temperature in the well gradually increases. When the temperature reaches the melting point of the material layer 6, the material layer 6 melts, and the filter holes of the outer filter screen 3 are opened, which does not affect the subsequent absorption and filtration of crude oil.

[0046] In the above embodiment, the structure of the mounting frame 1 is specifically as follows:

[0047] See attached Figure 1As shown, the installation frame 1 includes an upper connecting plate 11, a butt joint pipe 12, a support rod 13, a lower connecting plate 14, a connecting pipe 15 and a sealing cover 16; the upper connecting plate 11 is a circular structure and the middle part thereof is connected to the butt joint pipe 12 to realize the connection between the sand filter pipe and the oil pump pipe, the bottom of the upper connecting plate 11 is connected to the lower connecting plate 14 with a circular structure through at least four support rods 13, and the middle part of the lower connecting plate 14 is connected to the connecting pipe 15, the connecting pipe 15 is coaxially arranged with the butt joint pipe 12 and a sealing cover 16 is installed on the connecting pipe 15; in this solution, the connecting pipe 15 can be used in conjunction with the butt joint pipe 12 on another sand filter pipe (some oil production environments require multiple sand filter pipes to be connected and used in conjunction), and can also be used independently, and can be sealed with the sealing cover 16 when used independently. In addition, the detachable design of the sealing cover 16 and the connecting pipe 15 can also facilitate the subsequent unified cleaning and maintenance of the sand filter pipe. For example, when the inside of the sand filter pipe needs to be flushed and cleaned, it can facilitate the discharge of water flow and impurities and gravel inside the sand filter pipe;

[0048] In addition, in this plan, refer to the attached Figure 2 -Attached Figure 4 As shown, two coaxial upper annular grooves 111 are provided at the bottom of the upper connecting plate 11, and a lower annular groove 141 with the same size as the upper annular groove 111 and a one-to-one correspondence is provided at the top of the lower connecting plate 14, and the rotating assembly 2 is installed in the upper annular groove 111 and the lower annular groove 141.

[0049] In the above embodiment, the structure of the rotating component 2 is specifically as follows:

[0050] See attached Figure 2 -Attached Figure 6 As shown, the rotating assembly 2 includes a mounting groove 21, a ball 22, a rotating ring 23 and a connecting plate 24; there are four mounting grooves 21 and they are respectively installed in two upper annular grooves 111 and two lower annular grooves 141, and a plurality of balls 22 are installed along the bottom and side of the mounting groove 21 to form a rolling channel in the mounting groove 21. A rotating ring 23 is installed in the rolling channel, and the two rotating rings 23 at the upper end are connected by a connecting plate 24. The outer filter 3 is arranged between the two corresponding rotating rings 23 at the upper and lower ends of the outer side, and the inner filter 31 is arranged at Between the two corresponding upper and lower rotating rings 23 on the inner side, the rotating ring 23 on the upper inner side is connected to the driving component 4; in this embodiment, the rotating component 2 is designed to be rolling, and the rotation effect is more obvious compared to the sliding type (such as a slide block), and it is not easy to be stuck by sand and gravel impurities. The interaction between the balls 22 improves the rotation performance. In addition, through the rotating component 2 and the outer filter screen 3 and the inner filter screen 31, the upper and lower end surfaces of the outer filter screen 3 and the inner filter screen 31 can be closed to prevent sand and gravel impurities from entering the sand filter tube through the gap, and the cleaning and protection effect is stronger.

[0051] In the above embodiment, the structure of the driving component 4 is specifically as follows:

[0052] Refer to the attached Figure 1 and attached Figure 2 As shown, the driving assembly 4 includes a horizontal frame 41, a rotating rod 42, a propeller 43 and a connecting frame 44; the horizontal frame 41 is arranged in the butt joint 12 and its bottom is rotatably connected to the rotating rod 42, the rotating rod 42 is provided with a propeller 43 for receiving the impact of crude oil and a connecting frame 44 located below the propeller 43 and connected to the rotating ring 23 located on the inner upper side; in this embodiment, the propeller 43 generates a tangential force due to the impact of crude oil, which becomes the power to promote the automatic rotation of the propeller 43, when the propeller 43 rotates, the rotating rod 42 drives the connecting frame 44 to rotate, and finally the outer filter 3 and the inner filter 31 rotate;

[0053] In addition, in this plan, refer to the attached Figure 2 As shown, the propeller 43 is placed in the butt joint 12 to improve the impact effect of the crude oil. The crude oil is gathered at the butt joint 12 to form a thrust that drives the propeller 43 to rotate. In addition, considering the cleaning and filtering effect of the sand filter tube, in order to further reduce the entry of sand and gravel impurities into the oil pump and cause damage to the oil pump, the horizontal frame 41 and the connecting frame 44 both adopt a filter mesh structure to maintain normal operation while also having a filtering function.

[0054] In the above embodiment, the structure of the brush roller 5 is specifically as follows:

[0055] Refer to the attached Figure 1 and attached Figure 7 As shown, the brush roller 5 is cylindrical and the bottom end of the roller body is connected to the lower connecting plate 14, the top end of the roller body is below the connecting plate 24, and the brush body is in contact with the outer filter screen 3 and the inner filter screen 31; in this embodiment, two groups of brush rollers 5 are provided, and they are arranged circumferentially to improve the cleaning effect on the outer filter screen 3 and the inner filter screen 31;

[0056] In addition, in this scheme, considering the self-cleaning function of the brush roller 5, for this purpose, refer to the attached Figure 7 -Attached Fig. 9 As shown, a threaded hole 142 corresponding to the brush roller 5 is opened on the lower connecting plate 14, and a plug rod 51 is connected to the bottom end of the brush roller 5, and the plug rod 51 is inserted into the threaded hole 142, and a bolt 52 is connected to the bottom end of the plug rod 51, and the end of the bolt 52 is threadedly connected to the threaded hole 142, so that when the bolt 52 is in a loose state, the operating bolt 52 can rotate the brush roller 5. At this time, the rotating brush roller 5 contacts the outer filter screen 3 and the inner filter screen 31 in a stationary state, so that the gravel impurities on the brush roller 5 are brushed off; when the bolt 52 is in a tightened state, the position of the brush roller 5 is limited and stationary; it is worth noting that during the implementation of the scheme, the length of the bolt 52 can be set to one third of the depth of the threaded hole 142 to facilitate the rapid disassembly and assembly of the bolt 52.

[0057] In the above embodiment, considering that the outer filter screen 3 and the inner filter screen 31 are cleaned, there are gravel impurities in the space between the two. In order to discharge the gravel impurities at this position, for this purpose, refer to the attached Fig.10 -Attached Fig.13 As shown, two arc-shaped slag discharge ports 143 are symmetrically arranged on the lower connecting plate 14, and the slag discharge port 143 is located between the two lower annular grooves 141, and a slag discharge assembly 7 is installed in the two slag discharge ports 143; the structure of the slag discharge assembly 7 is specifically as follows: the slag discharge assembly 7 includes a slag guide bucket 71, a slag discharge groove 72 and a mounting plate 73; there are two slag guide buckets 71 and they are wide at the top and narrow at the bottom to facilitate the material guiding operation, the two slag guide buckets 71 are open at the top and bottom and are respectively fixed above the two slag discharge ports 143, two brush rollers 5 are arranged between the two slag guide buckets 71, and a slag discharge assembly 7 is provided below the two slag guide buckets 71. Grooves 72, the two slag discharge grooves 72 are respectively inserted into the two slag discharge ports 143 to collect the gravel impurities in the two slag guiding buckets 71, and the bottoms of the two slag discharge grooves 72 are commonly connected to a mounting plate 73, a central hole 731 is opened in the middle of the mounting plate 73 to be sleeved on the outside of the connecting pipe 15, and the mounting plate 73 is pressed and fixed by a sealing cover 16; in this embodiment, the gravel impurities generated by the outer filter screen 3 and the inner filter screen 31 after cleaning will be introduced into the slag discharge groove 72 through the slag guiding bucket 71 for unified collection. After the collection is completed, the sealing cover 16 can be loosened to remove the slag discharge groove 72 by operating the mounting plate 73 to complete the cleaning operation.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A self-cleaning composite sand filter pipe, comprising a mounting frame (1) and a drive assembly (4); characterized in that: Also includes A rotating assembly (2), an outer filter screen (3), an inner filter screen (31), a brush roller (5) and a material layer (6); An outer filter screen (3) with a circular structure and an inner filter screen (31) coaxial with the outer filter screen (3) are connected in the installation frame (1) via a rotating assembly (2), and the rotating assembly (2) is connected to a driving assembly (4) arranged at the top end of the installation frame (1), so that the driving assembly (4) causes the outer filter screen (3) and the inner filter screen (31) to rotate in a linked manner after being impacted by crude oil; A brush roller (5) is vertically arranged in the mounting frame (1), and the brush roller (5) is placed between the outer filter screen (3) and the inner filter screen (31) and is in contact with the outer filter screen (3) and the inner filter screen (31), so that when the outer filter screen (3) and the inner filter screen (31) are in a rotating state, the rotating outer filter screen (3) and the inner filter screen (31) are in contact with the brush roller (5) and perform a self-cleaning action; A material layer (6) is provided on the outer surface of the outer filter screen (3), the material layer (6) solidifies on the outer surface of the outer filter screen (3) at a certain temperature to close the filter holes of the outer filter screen (3), and melts on the outer surface of the outer filter screen (3) at a certain temperature to open the filter holes of the outer filter screen (3); The mounting frame (1) comprises an upper connecting plate (11), a butt pipe (12), a support rod (13), a lower connecting plate (14), a connecting pipe (15) and a sealing cover (16); The middle portion of the upper connecting plate (11) is connected to the butt-joining pipe (12), the bottom portion of the upper connecting plate (11) is connected to the lower connecting plate (14) via at least four supporting rods (13), and the middle portion of the lower connecting plate (14) is connected to the connecting pipe (15), the connecting pipe (15) and the butt-joining pipe (12) are coaxially arranged, and a sealing cover (16) is installed on the connecting pipe (15); The bottom of the upper connecting plate (11) is provided with two coaxial upper annular grooves (111), the top of the lower connecting plate (14) is provided with a lower annular groove (141) having the same size as the upper annular groove (111) and arranged one-to-one with each other, and a rotating assembly (2) is installed in the upper annular groove (111) and the lower annular groove (141); The rotating assembly (2) comprises a mounting groove (21), a ball (22), a rotating ring (23) and a connecting plate (24); There are four mounting grooves (21) which are respectively mounted in the two upper annular grooves (111) and the two lower annular grooves (141). The mounting grooves (21) are provided with a plurality of balls (22) along the bottom and side of the groove body, so that a rolling channel for mounting a rotating ring (23) is formed in the groove body of the mounting groove (21). The two rotating rings (23) at the upper ends are connected by a connecting plate (24). The outer filter screen (3) is arranged between the two rotating rings (23) at the upper and lower sides of the outer side corresponding to each other. The inner filter screen (31) is arranged between the two rotating rings (23) at the upper and lower sides of the inner side corresponding to each other. The rotating ring (23) at the upper inner side is connected to the driving assembly (4). The driving assembly (4) comprises a horizontal frame (41), a rotating rod (42), a propeller (43) and a connecting frame (44); The horizontal frame (41) is arranged in the butt joint pipe (12) and its bottom is rotatably connected to the rotating rod (42). The rotating rod (42) is provided with a propeller (43) and a connecting frame (44) located below the propeller (43) and used to be connected to the rotating ring (23) located on the inner upper side.

2. The self-cleaning composite sand filter tube according to claim 1, characterized in that: The horizontal frame (41) and the connecting frame (44) both adopt a filter screen structure.

3. A self-cleaning composite sand filter tube according to claim 2, characterized in that: The brush rollers (5) are provided in two groups and arranged in a circle. The brush rollers (5) are cylindrical and the bottom ends of the roller bodies are connected to the lower connecting plate (14). The top ends of the roller bodies are located below the connecting plate (24). The brush bodies are in contact with the outer filter screen (3) and the inner filter screen (31).

4. The self-cleaning composite sand filter tube according to claim 1, characterized in that: The material layer (6) is one of polyethylene wax and EVA wax.

5. The self-cleaning composite sand filter pipe according to claim 3, characterized in that: The lower connecting plate (14) is provided with a threaded hole (142) corresponding to the brush roller (5); the bottom end of the brush roller (5) is connected to an insertion rod (51), the insertion rod (51) is inserted into the threaded hole (142), and the bottom end of the insertion rod (51) is connected to a bolt (52), the end of the bolt (52) is threadedly connected to the threaded hole (142), so that when the bolt (52) is in a loosened state, the brush roller (5) can be rotated by operating the bolt (52).

6. A self-cleaning composite sand filter according to any one of claims 1 to 5, characterized in that: The lower connecting plate (14) is symmetrically provided with two arc-shaped slag discharge ports (143), the slag discharge ports (143) are located between the two lower annular grooves (141), and a slag discharge assembly (7) is installed in both slag discharge ports (143); The slag discharge assembly (7) comprises a slag guide bucket (71), a slag discharge trough (72) and a mounting plate (73); There are two slag guide buckets (71) with a structure that is wide at the top and narrow at the bottom. The two slag guide buckets (71) are open at the top and bottom and are respectively fixed above the two slag discharge ports (143). Two brush rollers (5) are arranged between the two slag guide buckets (71). A slag discharge groove (72) is respectively arranged below the two slag guide buckets (71). The two slag discharge grooves (72) are respectively inserted into the two slag discharge ports (143) to collect sand and gravel impurities in the two slag guide buckets (71). The bottoms of the two slag discharge grooves (72) are connected to a mounting plate (73) in common. A central hole (731) is opened in the middle of the mounting plate (73) so as to be sleeved on the outside of the connecting pipe (15). The mounting plate (73) is pressed and fixed by a sealing cover (16).

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