A downhole heat exchanger for a medium-deep geothermal well and a method thereof

Abstract

The application discloses a middle-deep geothermal well heat exchange device and a method thereof, and relates to the technical field of heat exchange devices.The device comprises a metal fixed pipe, a metal connecting pipe is fixedly installed on the inner side of the metal fixed pipe, a water inlet pipe and a water outlet pipe are fixedly and communicatively arranged on the two sides of the metal connecting pipe, a conveying pipe is fixedly and communicatively arranged on the water outlet pipe, the conveying pipe is fixedly and communicatively arranged through a filter box and a corrugated pipe, a sleeve ring is fixedly installed on the corrugated pipe, a connecting block is fixedly installed on the bottom of the sleeve ring, the connecting block is screw-connected on a first reciprocating threaded rod, the connecting block is slidingly connected on the inner wall of the filter box, and a filter screen is arranged below the corrugated pipe.The corrugated pipe is driven to reciprocate by the connecting block to prevent silt deposition;the first reciprocating threaded rod drives the cam to rotate through a transmission belt, the filter screen is periodically lifted to reciprocate, impurities fall off under the action of gravity and inertia, slide along the inclined screen surface into a collecting box, automatic cleaning is realized, manual cleaning is not needed, the maintenance difficulty is reduced, and stable operation of the system is ensured.

Description

Technical Field

[0001] This invention belongs to the technical field of heat exchange devices, and more specifically, relates to a medium-deep geothermal well downhole heat exchange device and method. Background Technology

[0002] With the introduction of my country's "dual carbon" goals, the development and utilization of geothermal energy has received increasing attention. As a renewable energy source with abundant reserves, low cost, and wide distribution, geothermal energy has enormous development potential, especially the medium-deep geothermal energy within the 200m-3000m depth range, where its utilization value is even more prominent. Currently, medium-deep geothermal well heat exchange technology, by deploying coaxial casings in deep wells, achieves closed-loop fluid circulation within a single well. Based on the principle of heat conduction, it efficiently exchanges heat with the surrounding strata, thus developing deep geothermal energy in a green manner of "extracting heat without extracting water." This effectively avoids the consumption and pollution of groundwater resources and is an important technological path to achieving clean heating.

[0003] However, current downhole heat exchange devices for medium-deep geothermal wells typically insert the heat extraction inner tube directly into the geothermal well. Due to the complex environment inside the well, containing a large amount of impurities such as silt and minerals, the water flow easily carries these impurities into the heat extraction inner tube during the circulating heat exchange process. As the fluid circulates, these impurities are continuously transported to the surface heat exchange device connected to the heat extraction inner tube. Over time, this accumulation can cause problems such as pipe blockage, decreased heat exchange efficiency, and accelerated equipment wear, seriously affecting the service life and operational stability of the heat exchange device. Summary of the Invention

[0004] In view of the problems in related technologies, this invention proposes a medium-deep geothermal well downhole heat exchange device and method to overcome the above-mentioned technical problems existing in the existing related technologies.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention discloses a downhole heat exchange device for medium-deep geothermal wells, comprising a metal fixed pipe, a metal connecting pipe fixedly installed on the inner side of the metal fixed pipe, an inlet pipe and an outlet pipe fixedly connected to both sides of the metal connecting pipe respectively, and a conveying pipe fixedly connected to the other end of the outlet pipe. The conveying pipe passes through a filter box and is fixedly connected to a corrugated pipe. A collar is fixedly installed on the outer wall of the corrugated pipe, and a connecting block is fixedly installed at the bottom of the collar. The connecting block is threadedly connected to a first reciprocating threaded rod and slidably connected to the inner wall of the filter box. A filter screen is provided below the corrugated pipe and is rotatably installed inside the filter box. The bottom of the filter screen abuts against a cam, and the cam is drivenly connected to the first reciprocating threaded rod through a transmission mechanism.

[0006] Furthermore, control valves are fixedly installed on both the inlet pipe and the outlet pipe, and the first reciprocating threaded rod is rotatably installed on the inner wall of the filter box.

[0007] Furthermore, the filter screen is arranged at an angle, and a discharge port is provided at the lower end of the angled direction of the filter screen. The discharge port is opened on the filter box, and a collection box is provided below the discharge port. The collection box is fixedly installed on the filter box.

[0008] Furthermore, the transmission mechanism includes a drive motor fixedly mounted on the filter box, the output end of the drive motor being fixedly mounted on a first reciprocating threaded rod, and a first transmission wheel being fixedly mounted on one end of the first reciprocating threaded rod.

[0009] Furthermore, the first transmission wheel is connected to a second transmission wheel via a transmission belt. The second transmission wheel is fixedly mounted on a rotating shaft, which is rotatably mounted inside the filter box. The cam is fixedly mounted on the rotating shaft.

[0010] Furthermore, the water outlet pipe is fixedly connected to a water suction pipe, which passes through the waterproof cylinder and is fixedly connected to the filter cylinder. The surface of the filter cylinder is provided with several water filtering holes.

[0011] Furthermore, the surface of the filter cartridge is in contact with the cleaning brush, one end of the cleaning brush is threadedly connected to a second reciprocating threaded rod, the other end of the cleaning brush is slidably connected to a guide rod, the second reciprocating threaded rod is rotatably mounted on the waterproof cartridge, and the guide rod is fixedly mounted on the waterproof cartridge.

[0012] Furthermore, one end of the second reciprocating threaded rod is fixedly installed with the output end of a waterproof motor, the waterproof motor is fixedly installed inside the waterproof cylinder, and the filter cartridge is fixedly installed on the waterproof cylinder.

[0013] Compared with the prior art, the present invention has the following advantages: 1. This invention uses a drive motor to rotate a first reciprocating threaded rod, causing the connecting block to drive the bellows to reciprocate within the filter box, continuously agitating the geothermal water and effectively preventing localized stagnation of water flow within the filter box, which would lead to sediment deposition and impurity accumulation. Simultaneously, the first reciprocating threaded rod drives a cam to rotate synchronously via a first transmission wheel, a transmission belt, and a second transmission wheel. The cam periodically lifts and releases the bottom of the filter screen, driving the filter screen to reciprocate and swing. This causes impurities adhering to the surface of the filter screen to automatically fall off under the influence of gravity and swing inertia, and slide along the inclined filter screen to the discharge port, falling into the collection box for centralized collection. This achieves automatic cleaning of the filter screen, eliminating the need for manual cleaning downhole, significantly reducing the difficulty of downhole maintenance, and ensuring the long-term stable operation of the filtration system.

[0014] 2. This invention features an automatic cleaning mechanism at the outlet pipe, where a waterproof motor-driven cleaning brush reciprocates to wash the filter holes on the filter cartridge surface. The waterproof motor drives the second reciprocating threaded rod to rotate, and the cleaning brush, limited by the guide rod, performs reciprocating linear motion along the filter cartridge axis, consistently adhering to the outer surface of the filter cartridge to repeatedly wash and remove impurities and deposits at the filter holes and orifices. This achieves automatic anti-clogging cleaning of the filter holes, avoiding the problem of reduced geothermal water intake and reduced heat exchange efficiency due to filter hole blockage. This cleaning mechanism, together with the self-cleaning filtration system inside the filter box, constitutes a multi-stage automatic filtration and cleaning system. Effective filtration and self-cleaning are performed before the geothermal water enters the heat exchange system and when it is discharged after heat exchange, ensuring the efficient, stable, and long-term operation of the entire medium-deep geothermal well downhole heat exchange device.

[0015] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0017] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is an enlarged schematic diagram of point A in the present invention; Figure 3 This is a schematic diagram of some parts of the present invention; Figure 4 This is a cross-sectional view of the filter box of the present invention; Figure 5 This is a cross-sectional view of the metal fixing tube of the present invention; Figure 6 This is an exploded view of some parts of the present invention.

[0018] The attached diagram lists the components represented by each number as follows: 1. Metal fixed pipe; 2. Metal connecting pipe; 3. Inlet pipe; 4. Outlet pipe; 5. Conveying pipe; 6. Filter box; 7. Corrugated pipe; 8. Collar; 9. Connecting block; 10. First reciprocating threaded rod; 11. Filter screen; 12. Cam; 13. Control valve; 14. Discharge port; 15. Collection box; 16. Drive motor; 17. First transmission wheel; 18. Transmission belt; 19. Second transmission wheel; 20. Rotating shaft; 21. Suction pipe; 22. Waterproof cylinder; 23. Filter cylinder; 24. Filter hole; 25. Cleaning brush; 26. Second reciprocating threaded rod; 27. Guide rod; 28. Waterproof motor. Detailed Implementation

[0019] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0020] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "top", "middle", "inner", etc., which indicate orientation or positional relationship, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention.

[0021] Please see Figures 1-6 As shown, this invention is a medium-deep geothermal well downhole heat exchange device, including a metal fixed pipe 1, a metal connecting pipe 2 fixedly installed on the inner side of the metal fixed pipe 1, an inlet pipe 3 and an outlet pipe 4 fixedly connected to the two sides of the metal connecting pipe 2 respectively, a conveying pipe 5 fixedly connected to the outlet pipe 4, the conveying pipe 5 passing through a filter box 6 and fixedly connected to a corrugated pipe 7, a collar 8 fixedly installed on the outer wall of the corrugated pipe 7, a connecting block 9 fixedly installed at the bottom of the collar 8, the connecting block 9 being threadedly connected to a first reciprocating threaded rod 10, and the connecting block 9 being slidably connected to the inner wall of the filter box 6 to realize the reciprocating extension and retraction movement of the corrugated pipe 7; a filter screen 11 is provided below the corrugated pipe 7, the filter screen 11 is rotatably installed inside the filter box 6, the bottom of the filter screen 11 abuts against a cam 12, the cam 12 being connected to the first reciprocating threaded rod 10 through a transmission mechanism, thereby driving the filter screen 11 to reciprocate and swing when the first reciprocating threaded rod 10 rotates to achieve a self-cleaning function.

[0022] The working principle of the medium-deep geothermal well downhole heat exchange device proposed in this invention is as follows: a metal fixed pipe 1 is installed inside the medium-deep geothermal well, serving as the main support structure of the entire heat exchange device. Coolant water flows into a metal connecting pipe 2 fixedly installed inside the metal fixed pipe 1 through an inlet pipe 3. The metal connecting pipe 2 connects the inlet pipe 3 and the outlet pipe 4, allowing the coolant water to flow continuously within the metal connecting pipe 2. Simultaneously, high-temperature geothermal water from the bottom of the well flows into the interlayer space between the metal fixed pipe 1 and the metal connecting pipe 2, where it undergoes thorough heat exchange with the coolant water flowing within the metal connecting pipe 2. The coolant water absorbs heat from the geothermal water, causing its temperature to rise, while the geothermal water releases heat, causing its temperature to drop.

[0023] After heat exchange, the geothermal water flows out of the metal connecting pipe 2 through the outlet pipe 4, and then enters the delivery pipe 5, which is fixedly connected to the outlet pipe 4. The delivery pipe 5 guides the geothermal water into the filter box 6 and is fixedly connected to the corrugated pipe 7, allowing the geothermal water to enter the corrugated pipe 7. A collar 8 is fixedly installed on the outer wall of the corrugated pipe 7, and a connecting block 9 is fixedly installed at the bottom of the collar 8. The connecting block 9 is threadedly connected to the first reciprocating threaded rod 10, and at the same time, the connecting block 9 is slidably connected to the inner wall of the filter box 6, which guides and limits the movement of the corrugated pipe 7.

[0024] When the first reciprocating threaded rod 10 rotates, since the connecting block 9 is threadedly connected to the first reciprocating threaded rod 10, and the connecting block 9 is restricted by the inner wall of the filter box 6 and cannot rotate with the first reciprocating threaded rod 10, the connecting block 9 makes a reciprocating linear motion along the axial direction of the first reciprocating threaded rod 10. The connecting block 9 drives the bellows 7 to make a reciprocating motion inside the filter box 6 through the collar 8. The bellows 7 constantly changes position, so that the geothermal water flowing into the filter box 6 from the delivery pipe 5 will not accumulate in one place in the filter box 6, but will be continuously agitated and dispersed with the reciprocating movement of the bellows 7. This avoids the problem of sediment deposition and impurity accumulation caused by local water flow stagnation, ensures uniform water flow inside the filter box 6, and provides a good water flow environment for the normal operation of the filter screen 11.

[0025] Meanwhile, the first reciprocating threaded rod 10 is connected to the cam 12 via a transmission mechanism. When the first reciprocating threaded rod 10 rotates, the cam 12 rotates synchronously. The cam 12 is installed at the bottom of the filter screen 11 and abuts against the bottom of the filter screen 11. The rotation of the cam 12 causes its contour to periodically lift and release the bottom of the filter screen 11, thereby driving the filter screen 11 to reciprocate inside the filter box 6. During the reciprocating oscillation, impurities attached to the surface of the filter screen 11 are continuously detached under the combined action of gravity and oscillation inertia, realizing the self-cleaning function of the filter screen 11 and ensuring that the filter screen 11 always maintains a good filtration effect.

[0026] After being filtered by filter screen 11, the geothermal water continues to be discharged through delivery pipe 5, completing the entire heat exchange and filtration cycle. The metal fixed pipe 1, metal connecting pipe 2, inlet pipe 3, outlet pipe 4, delivery pipe 5, filter box 6, corrugated pipe 7, collar 8, connecting block 9, first reciprocating threaded rod 10, filter screen 11, and cam 12 work together in concert. The reciprocating movement of corrugated pipe 7 effectively prevents localized water accumulation within the filter box 6, and cam 12 drives the filter screen 11 to reciprocate for automatic cleaning. Together, they achieve efficient heat exchange and automatic filtration and cleaning functions in medium-deep geothermal wells.

[0027] In one embodiment, for the above-mentioned inlet pipe 3, control valves 13 are fixedly installed on both the inlet pipe 3 and the outlet pipe 4 to control the on / off state and flow rate of the geothermal water; the first reciprocating threaded rod 10 is rotatably installed on the inner wall of the filter box 6 to ensure its rotational stability and to achieve threaded transmission cooperation with the connecting block 9.

[0028] In one embodiment, the filter screen 11 is inclined, and a discharge port 14 is provided at the lower end of the inclined direction of the filter screen 11. The discharge port 14 is opened on the filter box 6, and a collection box 15 is provided below the discharge port 14. The collection box 15 is fixedly installed on the filter box 6 and is used to collect the impurities and sediments scraped off the filter screen 11 for subsequent cleaning.

[0029] In one embodiment, the transmission mechanism includes a drive motor 16 fixedly mounted on the filter box 6. The output end of the drive motor 16 is fixedly mounted on the first reciprocating threaded rod 10. One end of the first reciprocating threaded rod 10 is fixedly mounted with a first transmission wheel 17. When the drive motor 16 is working, it drives the first reciprocating threaded rod 10 to rotate, thereby driving the connecting block 9 and the bellows 7 to achieve reciprocating telescopic movement.

[0030] In one embodiment, the first transmission wheel 17 is connected to a second transmission wheel 19 via a transmission belt 18. The second transmission wheel 19 is fixedly mounted on a rotating shaft 20, which is rotatably mounted inside the filter box 6. The cam 12 is fixedly mounted on the rotating shaft 20, so that when the first reciprocating threaded rod 10 rotates, it drives the rotating shaft 20 and the cam 12 to rotate synchronously via the first transmission wheel 17, the transmission belt 18, and the second transmission wheel 19, thereby driving the filter screen 11 to oscillate back and forth.

[0031] In one embodiment, the water outlet pipe 4 is fixedly connected to a water suction pipe 21. The water suction pipe 21 passes through the waterproof cylinder 22 and is fixedly connected to the filter cylinder 23. The surface of the filter cylinder 23 is provided with a plurality of water filter holes 24. After the geothermal water enters the interior of the filter cylinder 23 through the water filter holes 24, it is transported to the metal connecting pipe 2 through the water suction pipe 21 and the water outlet pipe 4 for heat exchange. The water filter holes 24 play a role in initially filtering impurities in the geothermal water.

[0032] In one embodiment, for the filter cartridge 23, the outer surface of the filter cartridge 23 is in contact with the cleaning brush 25. One end of the cleaning brush 25 is threadedly connected to a second reciprocating threaded rod 26, and the other end is slidably connected to a guide rod 27. The second reciprocating threaded rod 26 is rotatably mounted on the waterproof cylinder 22, and the guide rod 27 is fixedly mounted on the waterproof cylinder 22. When the second reciprocating threaded rod 26 rotates, it drives the cleaning brush 25 to move back and forth along the outer surface of the filter cartridge 23, thereby realizing automatic cleaning of the water filter holes 24 on the surface of the filter cartridge 23 and preventing clogging.

[0033] In one embodiment, for the second reciprocating threaded rod 26, one end of the second reciprocating threaded rod 26 is fixedly installed with the output end of the waterproof motor 28. The waterproof motor 28 is fixedly installed inside the waterproof cylinder 22, and the filter cylinder 23 is fixedly installed on the waterproof cylinder 22. The waterproof motor 28 drives the second reciprocating threaded rod 26 to rotate, thereby driving the cleaning brush 25 to reciprocate to clean the filter cylinder 23, ensuring the unobstructed flow of the filter holes 24 and the heat exchange efficiency.

[0034] The working principle of the medium-deep geothermal well downhole heat exchange device proposed in this invention is as follows: A metal fixed pipe 1 is installed inside the medium-deep geothermal well, serving as the main support structure of the entire heat exchange device. Coolant water flows into a metal connecting pipe 2 fixedly installed inside the metal fixed pipe 1 through an inlet pipe 3. The metal connecting pipe 2 connects the inlet pipe 3 and the outlet pipe 4, allowing the coolant water to flow continuously within the metal connecting pipe 2. Simultaneously, high-temperature geothermal water from the bottom of the well flows into the interlayer space between the metal fixed pipe 1 and the metal connecting pipe 2, undergoing thorough heat exchange with the coolant water flowing within the metal connecting pipe 2. The coolant water absorbs heat from the geothermal water, increasing in temperature, while the geothermal water releases heat, decreasing in temperature. Control valves 13 are fixedly installed on both the inlet pipe 3 and the outlet pipe 4. These control valves 13 control the on / off state and flow rate of the geothermal water. Operators can adjust the flow rate of the inlet pipe 3 and the outlet pipe 4 according to actual heat exchange needs, achieving precise control of the heat exchange process.

[0035] After heat exchange, the geothermal water flows out of the metal connecting pipe 2 through the outlet pipe 4, and then enters the delivery pipe 5, which is fixedly connected to the outlet pipe 4. The delivery pipe 5 guides the geothermal water into the filter box 6 and is fixedly connected to the corrugated pipe 7, allowing the geothermal water to enter the corrugated pipe 7. A collar 8 is fixedly installed on the outer wall of the corrugated pipe 7, and a connecting block 9 is fixedly installed at the bottom of the collar 8. The connecting block 9 is threadedly connected to the first reciprocating threaded rod 10, and at the same time, the connecting block 9 is slidably connected to the inner wall of the filter box 6, which guides and limits the movement of the corrugated pipe 7. The first reciprocating threaded rod 10 is rotatably installed on the inner wall of the filter box 6 to ensure its rotational stability and to achieve threaded transmission with the connecting block 9.

[0036] The drive motor 16 is fixedly mounted on the filter box 6, and the output end of the drive motor 16 is fixedly mounted on the first reciprocating threaded rod 10. A first transmission wheel 17 is fixedly mounted on one end of the first reciprocating threaded rod 10. When the drive motor 16 operates, it drives the first reciprocating threaded rod 10 to rotate. Since the connecting block 9 is threadedly connected to the first reciprocating threaded rod 10, and the connecting block 9 is restricted by the inner wall of the filter box 6 and cannot rotate with the first reciprocating threaded rod 10, the connecting block 9 performs a reciprocating linear motion along the axial direction of the first reciprocating threaded rod 10. The connecting block 9 drives the bellows 7 to reciprocate inside the filter box 6 via the collar 8. The bellows 7 continuously changes position, preventing the geothermal water flowing into the filter box 6 from accumulating in one place. Instead, it is continuously agitated and dispersed with the reciprocating movement of the bellows 7, avoiding sediment deposition and impurity accumulation caused by localized water flow stagnation. This ensures uniform water flow inside the filter box 6 and provides a good water flow environment for the normal operation of the filter screen 11.

[0037] While the first reciprocating threaded rod 10 rotates, the first transmission wheel 17 is connected to the second transmission wheel 19 via the transmission belt 18. The second transmission wheel 19 is fixedly mounted on the rotating shaft 20, which is rotatably mounted inside the filter box 6. The cam 12 is fixedly mounted on the rotating shaft 20. When the first reciprocating threaded rod 10 rotates, it drives the rotating shaft 20 and the cam 12 to rotate synchronously through the first transmission wheel 17, the transmission belt 18, and the second transmission wheel 19. The cam 12 is mounted on the bottom of the filter screen 11 and abuts against the bottom of the filter screen 11. The rotation of the cam 12 causes its contour to periodically lift and release the bottom of the filter screen 11, thereby driving the filter screen 11 to reciprocate inside the filter box 6. During the reciprocating oscillation, impurities attached to the surface of the filter screen 11 are continuously detached under the combined action of gravity and oscillation inertia. The filter screen 11 is arranged at an angle, and a discharge port 14 is provided at the lower end of the angled filter screen 11. The discharge port 14 is located on the filter box 6, and a collection box 15 is provided below the discharge port 14. The collection box 15 is fixedly installed on the filter box 6. Impurities and sediments scraped off the filter screen 11 slide down the angled filter screen 11 under the action of gravity and fall from the discharge port 14 into the collection box 15 below for collection, which facilitates subsequent unified cleaning and ensures that the filter screen 11 always maintains a good filtration effect.

[0038] The outlet pipe 4 is fixedly connected to the suction pipe 21, which passes through the waterproof cylinder 22 and is fixedly connected to the filter cylinder 23. The filter cylinder 23 is fixedly installed on the waterproof cylinder 22, and several filter holes 24 are opened on the surface of the filter cylinder 23. After the geothermal water enters the interior of the filter cylinder 23 through the filter holes 24, it is transported to the metal connecting pipe 2 through the suction pipe 21 and the outlet pipe 4 for heat exchange. The filter holes 24 play a role in initially filtering impurities in the geothermal water, performing a pretreatment before the geothermal water enters the heat exchange system, reducing the impact and wear of large particles on the heat exchange pipes.

[0039] The outer surface of the filter cartridge 23 is in contact with the cleaning brush 25. One end of the cleaning brush 25 is threadedly connected to a second reciprocating threaded rod 26, and the other end is slidably connected to a guide rod 27. The second reciprocating threaded rod 26 is rotatably mounted on the waterproof cylinder 22, and the guide rod 27 is fixedly mounted on the waterproof cylinder 22. The guide rod 27 guides and limits the movement of the cleaning brush 25, ensuring that the cleaning brush 25 can only reciprocate linearly along the axial direction of the filter cartridge 23. The output end of a waterproof motor 28 is fixedly mounted on one end of the second reciprocating threaded rod 26, and the waterproof motor 28 is fixedly mounted inside the waterproof cylinder 22. The waterproof motor 28 drives the second reciprocating threaded rod 26 to rotate. Since the cleaning brush 25 and the second reciprocating threaded rod 26 are threadedly connected, and the cleaning brush 25 is restricted by the guide rod 27 from rotating with the second reciprocating threaded rod 26, the cleaning brush 25 reciprocates linearly along the axial direction of the second reciprocating threaded rod 26. During its reciprocating motion, the cleaning brush 25 remains in contact with the outer surface of the filter cartridge 23, repeatedly brushing the filter holes 24 on the surface of the filter cartridge 23 to remove impurities and deposits attached to the area around and at the openings of the filter holes 24. This achieves automatic cleaning of the filter holes 24 on the surface of the filter cartridge 23, preventing the filter holes 24 from being blocked by impurities and affecting the normal intake of geothermal water, thus ensuring the unobstructed flow of the filter holes 24 and the heat exchange efficiency.

[0040] After being filtered by filter screen 11, the geothermal water continues to be discharged through delivery pipe 5, completing the entire heat exchange and filtration cycle. The components 1 (metal fixed pipe), 2 (metal connecting pipe), 3 (inlet pipe), 4 (outlet pipe), 5 (transport pipe), 6 (filter box), 7 (corrugated pipe), 8 (ring), 9 (connecting block), 10 (first reciprocating threaded rod), 11 (filter screen), 12 (cam), 13 (control valve), 14 (discharge port), 15 (collection box), 16 (drive motor), 17 (first transmission wheel), 18 (transmission belt), 19 (second transmission wheel), 20 (rotating shaft), 21 (suction pipe), 22 (waterproof cylinder), 23 (filter cartridge), 24 (filter holes), 25 (cleaning brush), 26 (second reciprocating threaded rod), 27 (guide rod), and 28 (waterproof motor) work together. The drive motor 16 drives the corrugated pipe 7 to reciprocate and extend to prevent water from accumulating locally in the filter box 6. At the same time, the cam 12 drives the filter screen 11 to reciprocate and swing to achieve automatic cleaning. Impurities fall into the collection box 15 through the discharge port 14 and are collected. The waterproof motor 28 drives the cleaning brush 25 to reciprocate and clean the filter cartridge 23 to ensure that the filter holes 24 are unobstructed. The entire device achieves efficient heat exchange and multi-stage automatic filtration and cleaning functions in medium-deep geothermal wells, significantly reducing the difficulty of downhole maintenance and ensuring the long-term stable operation of the heat exchange system.

[0041] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] The preferred embodiments of the invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. The embodiments selected and specifically described in this specification are intended to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A downhole heat exchange device for medium-deep geothermal wells, comprising a metal fixed pipe (1), characterized in that: A metal connecting pipe (2) is fixedly installed on the inner side of the metal fixed pipe (1). A water inlet pipe (3) and a water outlet pipe (4) are fixedly connected on both sides of the metal connecting pipe (2). A conveying pipe (5) is fixedly connected to the water outlet pipe (4). The conveying pipe (5) passes through the filter box (6) and is fixedly connected to the corrugated pipe (7). A collar (8) is fixedly installed on the corrugated pipe (7). A connecting block (9) is fixedly installed at the bottom of the collar (8). The connecting block (9) is threadedly connected to the first reciprocating threaded rod (10). The connecting block (9) is slidably connected to the inner wall of the filter box (6). A filter screen (11) is provided below the corrugated pipe (7). The filter screen (11) is rotatably installed inside the filter box (6). The bottom of the filter screen (11) abuts against the cam (12). The cam (12) is connected to the first reciprocating threaded rod (10) through a transmission mechanism.

2. The downhole heat exchange device for medium-deep geothermal wells according to claim 1, characterized in that, Both the inlet pipe (3) and the outlet pipe (4) are fixedly equipped with control valves (13), and the first reciprocating threaded rod (10) is rotatably installed on the inner wall of the filter box (6).

3. The downhole heat exchange device for medium-deep geothermal wells according to claim 2, characterized in that, The filter screen (11) is inclined, and a discharge port (14) is provided in the inclined direction of the filter screen (11). The discharge port (14) is opened on the filter box (6). A collection box (15) is provided below the discharge port (14). The collection box (15) is fixedly installed on the filter box (6).

4. A medium-deep geothermal well downhole heat exchange device according to claim 3, characterized in that, The transmission mechanism includes a drive motor (16) fixedly installed on the filter box (6), the output end of the drive motor (16) is fixedly installed on the first reciprocating threaded rod (10), and a first transmission wheel (17) is fixedly installed on one end of the first reciprocating threaded rod (10).

5. A medium-deep geothermal well downhole heat exchange device according to claim 4, characterized in that, The first drive wheel (17) is connected to the second drive wheel (19) via the drive belt (18) and is fixedly installed on the rotating shaft (20). The rotating shaft (20) is rotatably installed inside the filter box (6), and the cam (12) is fixedly installed on the rotating shaft (20).

6. A medium-deep geothermal well downhole heat exchange device according to claim 5, characterized in that, The water outlet pipe (4) is fixedly connected to the water suction pipe (21), the water suction pipe (21) passes through the waterproof cylinder (22) and is fixedly connected to the filter cylinder (23), and the surface of the filter cylinder (23) is provided with a number of water filtering holes (24).

7. A medium-deep geothermal well downhole heat exchange device according to claim 6, characterized in that, The surface of the filter cartridge (23) is in contact with the cleaning brush (25). One end of the cleaning brush (25) is threadedly connected to a second reciprocating threaded rod (26), and the other end is slidably connected to a guide rod (27). The second reciprocating threaded rod (26) is rotatably mounted on the waterproof cylinder (22), and the guide rod (27) is fixedly mounted on the waterproof cylinder (22).

8. A medium-deep geothermal well downhole heat exchange device according to claim 7, characterized in that, The output end of a waterproof motor (28) is fixedly installed at one end of the second reciprocating threaded rod (26). The waterproof motor (28) is fixedly installed inside the waterproof cylinder (22), and the filter cylinder (23) is fixedly installed on the waterproof cylinder (22).

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