Coaxial sleeve heat exchanger used in geothermal well

Abstract

The invention relates to the field of energy-saving heat exchange devices, and discloses a coaxial sleeve heat exchanger used in a geothermal well, the coaxial sleeve heat exchanger comprises a plurality of inner sleeves and a plurality of outer sleeves, the inner sleeves are coaxially arranged in the outer sleeves, the tops of the inner sleeves are coaxially and fixedly connected with inner sleeve female buckles, the outer side walls of the bottoms of the inner sleeves are provided with threads, and the inner sleeves are coaxially and fixedly connected with the inner sleeve female buckles. The inner casing pipe located on the upper portion is in threaded connection with the inner casing pipe female buckle of the inner casing pipe located on the lower portion, a driving assembly and multiple sets of supporting plates are arranged on the inner casing pipes, the multiple sets of supporting plates are arranged in the circumferential direction of the inner casing pipes, the supporting plates can rotate, and when the inner casing pipe located on the upper portion rotates into the inner casing pipe female buckle on the inner casing pipe located on the lower portion, the driving assembly drives the supporting plates to rotate. The multiple sets of supporting plates can be driven by the driving assembly to rotate to abut against the inner wall of the outer sleeve. The device has the effects that the inner sleeve and the outer sleeve can be put down and installed conveniently, and meanwhile the stability of the inner sleeve in the putting-down process is improved.

Description

Technical Field

[0001] This application relates to the field of energy-saving heat exchange devices, and particularly to a coaxial casing heat exchanger for geothermal wells. Background Art

[0002] In the context of the global energy structure transformation and the increasing awareness of environmental protection, geothermal energy, as a clean and renewable green energy, is gradually coming into the public view and becoming a new trend leading to a fashionable life. The medium-deep geothermal well downhole heat exchange heating technology is an efficient way to utilize geothermal resources. This technology drills geothermal wells thousands of meters deep underground and uses a coaxial casing heat exchanger to transfer underground heat energy to the ground. The coaxial casing heat exchanger consists of an inner and an outer casing. An annular space is formed between the two casings as the medium channel for heat exchange. The working fluid is driven by a ground circulation pump to circulate in the pipeline, absorb heat or discharge heat from the underground, so as to achieve the purpose of heating or cooling.

[0003] When lowering the casing of a deep geothermal well, due to the long length of the casing to be lowered, a segmented lowering process is generally adopted. The specific process is as follows: The first casing is placed into the casing chuck at the wellhead through the suspension mechanism on the drilling rig and fixed, and the casing male thread at its top is exposed outside the chuck. Then the suspension mechanism hoists the second casing, and the worker puts the bottom of it into the casing male thread at the top of the first casing. The driller then operates the CRT (casing lowering tool) equipped on the drilling rig to make the CRT extend into the second casing and internally support and fix it, driving the second casing to rotate and descend, thus completing the threaded connection of the two casings. Then the chuck is loosened, and the drilling rig drives the two casings to descend. When the second casing descends to a position where its casing male thread is close to the chuck, it stops, and the second casing is fixed using the chuck. Then the third casing is installed... and so on, until the connection and lowering of all casings are completed.

[0004] In the related art, the Chinese utility model patent with the authorized publication number CN210718770U discloses a coaxial casing deep well heat exchanger, which includes an outer casing and an inner casing arranged coaxially. The outer casing is lowered into the well for heat transfer in contact with the rock and soil. The inner casing is lowered into the outer casing for the circulation of the heat exchange medium. The outer casing and the inner casing are fixedly connected by multiple spacer plates, and a sealing cover is installed on the upper side between the outer casing and the inner casing. A plurality of drainage holes are evenly formed in the bottom wall of the inner casing. When using this coaxial casing deep well heat exchanger, low-temperature water enters the annular cavity between the outer casing and the inner casing from the outer casing to exchange heat with the rock and soil. After the water is heated, it enters the inner casing through the drainage holes, and the heated high-temperature water is pumped from the bottom to the top of the inner casing by an external circulation power and utilized, thus completing the extraction and utilization of geothermal energy.

[0005] In view of the above related technologies, the inventor found that in this solution, the outer casing and the inner casing are fixedly connected as a whole through a spacer plate, and when lowering, they can only be lowered as a whole into the geothermal well. Once the casing is too long, not only is the transportation process inconvenient, but it is also inconvenient when lowering into the well; if the outer casing and the inner casing are lowered separately and then connected, the stability of the inner casing cannot be guaranteed during the lowering process, and it is easy to tilt during the lowering process, thus affecting the installation quality. Summary of the Invention

[0006] In order to facilitate the lowering and installation of the inner casing and the outer casing, and at the same time improve the stability of the inner casing during the lowering process, the present application provides a coaxial casing heat exchanger for use in a geothermal well.

[0007] The coaxial casing heat exchanger for use in a geothermal well provided by the present application adopts the following technical solutions: A coaxial casing heat exchanger for use in a geothermal well includes a plurality of inner casings and a plurality of outer casings. The inner casings are coaxially arranged inside the outer casings. The plurality of inner casings and the plurality of outer casings are all arranged in sequence along the vertical direction. The top of the inner casing is coaxially fixedly connected with an inner casing female thread, and a thread is provided on the outer side wall of the bottom. The top of the outer casing is coaxially fixedly connected with an outer casing female thread, and a thread is provided on the outer side wall of the bottom. The inner casing female thread of the inner casing located above is threadedly connected with the inner casing female thread of the inner casing located below. The outer casing female thread of the outer casing located above is threadedly connected with the outer casing female thread of the outer casing located below. No thread is provided on the bottom side wall of the lowermost inner casing, but a plurality of flow holes are provided. The outer casing is fixed to the well wall of the heat exchange well by cement. A driving component and a plurality of groups of support plates are provided on the inner casing. The plurality of groups of support plates are arranged circumferentially along the inner casing. The support plates are rotatable. When the inner casing located above rotates into the inner casing female thread on the inner casing located below, the driving component can drive the plurality of groups of support plates to rotate and abut against the inner wall of the outer casing.

[0008] By adopting the above technical solutions, since both the inner casing and the outer casing are modularized, only segmented installation is required during installation, so the convenience of transportation and installation can be greatly improved; during installation, first use a casing lowering tool and a chuck to install the outer casing one by one. After the installation is completed, inject cement between the outer casing and the well wall of the heat exchange well to fix it, and then install the inner casing. The installation steps of the inner casing are the same as those of the outer casing, but it should be noted that the first inner casing installed must be the inner casing with flow holes provided at the bottom; During the installation process, when the upper inner sleeve is screwed into the female thread of the lower inner sleeve, it can drive the operation of the driving component on the lower inner sleeve, thereby driving the rotation of multiple support plates. When the two inner sleeves are connected, the support plates just rotate to abut against the inner wall of the outer sleeve, so as to support the lower inner sleeve. When the two inner sleeves are lowered subsequently, the inner sleeves can be prevented from shaking or tilting, thereby improving the stability of the inner sleeve lowering process.

[0009] Optionally, the driving component includes a waterproof box fixedly connected to the top of the outer wall of the inner sleeve. A driving gear ring is rotatably connected in the waterproof box and is coaxially arranged with the inner sleeve. A plurality of driven gears are also rotatably connected in the waterproof box, and all the driven gears are engaged with the driving gear ring. A rotating rod is coaxially and fixedly connected to the bottom of each driven gear. A push rod is arranged on each rotating rod. The plurality of rotating rods are arranged in one-to-one correspondence with the plurality of support plates. The push rod is used to push the support plate to rotate. A driving ring is coaxially and fixedly connected to the top of the driving gear ring. The driving ring extends out of the top of the waterproof box. A connecting plate is arranged on the top of the driving ring. Except for the lowermost inner sleeve, connecting rods are arranged at the bottoms of the other inner sleeves. Positioning holes are formed in the connecting plate, and the connecting rods are used to be inserted into the positioning holes.

[0010] By adopting the above technical solution, when the upper inner sleeve descends onto the female thread of the lower inner sleeve, at this time, the worker aligns the connecting rod at the bottom of the upper inner sleeve with the positioning hole on the connecting plate at the top of the lower inner sleeve, and then the drilling rig lowers the upper inner sleeve. The connecting rod is inserted into the positioning hole. When the bottom of the upper inner sleeve enters the female thread of the lower inner sleeve at the top of the lower inner sleeve, the casing lowering tool drives the upper inner sleeve to rotate and gradually descend. At this time, the connecting rod drives the driving ring of the lower inner sleeve to rotate, the driving ring drives the driving gear ring to rotate, the driving gear ring drives the four driven gears to rotate, and the four driven gears respectively drive the rotating rods thereon to rotate. Each rotating rod drives the push rod thereon to rotate away from the inner sleeve, and the push rod pushes the support plate to rotate towards the inner wall of the outer sleeve. When the bottom of the upper inner sleeve is completely screwed into the female thread of the lower inner sleeve at the top of the lower inner sleeve, the support plate of the lower inner sleeve just rotates to abut against the inner wall of the outer sleeve, thus completing the support and positioning of the lower inner sleeve. During the process of connecting the two inner sleeves, it is necessary to screw the upper inner sleeve into the female thread of the lower inner sleeve. Due to the connection between the connecting rod and the connecting plate, the driving component on the lower inner sleeve can be driven to operate simultaneously, that is, multiple support plates can be driven to rotate, so as to complete the support of the inner sleeve. By installing the two sleeves, the support of the inner sleeve can be realized simultaneously. The whole process is simple and fast, which facilitates the installation of workers and improves the installation efficiency. In addition, for the innermost sleeve located at the uppermost position, the driving ring needs to be manually rotated to open the support plate, thereby completing the support and positioning of all the innermost sleeves.

[0011] Optionally, four groups of the support plates are provided. The four groups of support plates are evenly spaced along the circumferential direction of the innermost sleeve. Four fixing plates are fixedly connected to the bottom surface of the waterproof box. Along the circumferential direction of the waterproof box, the four fixing plates and the four groups of support plates are arranged in a cross pattern. The top of the support plate is rotatably connected between two adjacent fixing plates. The rotating rods are also provided in four. The push rods on each rotating rod are all located on the side of the corresponding support plate facing the innermost sleeve.

[0012] By adopting the above technical solution, the driving assembly can drive the four rotating rods to rotate simultaneously, thereby driving the four groups of push rods to rotate. The four groups of push plates can simultaneously push the four groups of support plates to rotate. The four groups of support plates support the innermost sleeve evenly along the circumferential direction of the innermost sleeve, thereby improving the stability of the support for the innermost sleeve.

[0013] Optionally, each group of the support plates includes three support plates. The three support plates are arranged at equal intervals in the vertical direction. Three push rods are also provided on each rotating rod. The three push rods are respectively used to push the three support plates.

[0014] By adopting the above technical solution, each group of support plates includes three support plates. The three support plates are arranged at equal intervals in the vertical direction, so as to support the innermost sleeve evenly along the axial direction of the innermost sleeve, further improving the stability of the support for the innermost sleeve.

[0015] Optionally, the free end of the support plate is set to be arc-shaped and has the same diameter as the inner wall diameter of the outer sleeve.

[0016] By adopting the above technical solution, when the support plate abuts against the inner wall of the outer sleeve, since the free end of the support plate is set to be arc-shaped and has the same diameter as the inner wall diameter of the outer sleeve, it can be completely attached to the inner wall of the outer sleeve, thereby ensuring the stability of the innermost sleeve when it is lowered.

[0017] Optionally, the push rod is set to be arc-shaped and the concave surface faces the innermost sleeve.

[0018] By adopting the above technical solution, before the support plate is unfolded, the free end of the push rod bends towards the innermost sleeve. Since the push rod is set to be arc-shaped and the concave surface faces the innermost sleeve, space can be saved, which is convenient for the storage and transportation of the innermost sleeve.

[0019] Optionally, a plurality of diversion grooves are formed in the lower part of the support plate.

[0020] By adopting the above technical solution, after the heat exchange water source enters between the inner and outer sleeves, it slides onto the support plate, and the water flow slides along the inclined direction of the support plate towards the direction close to the inner wall of the outer sleeve, thereby increasing the contact area with the inner wall of the outer sleeve and improving the heat exchange effect; at the same time, part of the water flow can flow from the diversion groove to the next support plate. During this process, due to the guiding effect of the support plate, the contact time between the water flow and the inner wall of the outer sleeve is extended, further improving the heat exchange effect.

[0021] Optionally, a diversion plate is hinged to one side of each support plate facing the inner sleeve, and the other end of the diversion plate is connected to the support plate by a chain. When the support plate abuts against the inner wall of the outer sleeve, the diversion plate rotates to be located below the diversion groove, and the bottom of the diversion plate is inclined towards the inner sleeve.

[0022] By adopting the above technical solution, the water flow flows along the support plate and flows from the diversion groove to the diversion plate below. At the same time, due to the blocking of the blocking plate, this part of the water flow flows along the diversion plate to the next support plate, and then this process is continuously repeated. Since the water flow needs to pass through the cross-guiding of the support plate and the diversion plate to flow to the bottom of the well, the contact time between the water flow and the inner wall of the outer sleeve is extended, further improving the heat exchange effect of the water flow.

[0023] Optionally, a blocking plate is vertically arranged on one side of each support plate facing the inner sleeve, and the blocking plate is fixedly connected between two adjacent fixing plates. The blocking plate is located below the corresponding push rod. When the support plate is in a vertical state, the diversion plate rotates to and the free end is located above the hinged end, and the diversion plate is located between the support plate and the blocking plate.

[0024] By adopting the above technical solution, after the support plate is unfolded, the blocking plate can guide the water flow; before the support plate is unfolded, the diversion plate and the chain are both stored between the support plate and the blocking plate, thus saving space and facilitating the transportation of the inner sleeve.

[0025] Optionally, a cover plate is welded between the female buckle of the inner sleeve and the female buckle of the outer sleeve at the topmost position, and a water injection port is opened on the cover plate.

[0026] By adopting the above technical solution, after the inner sleeve is installed, the cover plate is welded between the female buckle of the inner sleeve and the female buckle of the outer sleeve, thereby fixing the inner sleeve, preventing the impact of water flow from affecting the stability of the support plate, and improving the stability of the inner sleeve and the support plate; at the same time, the heat exchange water source can be input between the inner and outer sleeves from the water injection port, and the cover plate can prevent sundries from falling between the inner and outer sleeves.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: 1. Since both the inner sleeve and the outer sleeve are modularly arranged, only segmented installation is required during installation, so the convenience of transportation and installation can be greatly improved. During the installation process, when the upper inner sleeve is screwed into the female thread of the lower inner sleeve, the driving component on the lower inner sleeve can be driven to operate, thereby driving the rotation of multiple support plates. When the two inner sleeves are connected, the support plates just rotate to abut against the inner wall of the outer sleeve, thus supporting the lower inner sleeve. When the two inner sleeves are lowered subsequently, the inner sleeve can be prevented from shaking or tilting, thereby improving the stability of the inner sleeve during the lowering process; 2. During the process of connecting the two inner sleeves, the upper inner sleeve needs to be screwed into the female thread of the lower inner sleeve. Due to the connection of the connecting rod and the connecting plate, the driving component on the lower inner sleeve can be driven to operate simultaneously, that is, multiple support plates can be driven to rotate, thereby completing the support for the inner sleeve. By installing the two sleeves, the support for the inner sleeve can be realized simultaneously. The whole process is simple and fast, which facilitates the installation by workers and improves the installation efficiency; 3. The water flow flows along the support plate and flows from the diversion groove to the lower diversion plate. At the same time, due to the blockage of the blocking plate, this part of the water flow flows along the diversion plate to the next support plate, and then this process is continuously repeated. Since the water flow needs to pass through the cross - guidance of the support plate and the diversion plate to flow to the bottom of the well, the contact time between the water flow and the inner wall of the outer sleeve is prolonged, further improving the heat exchange effect of the water flow. Description of the Drawings

[0028] Figure 1 is a schematic diagram of the overall structure of an embodiment of the present application; Figure 2 is a front - view sectional view of the overall structure of an embodiment of the present application, mainly used to show the support component; Figure 3 is a partial sectional view of the structure of an embodiment of the present application, mainly used to show the driving component and the diversion component; Figure 4 is a partial structure schematic diagram of an embodiment of the present application, mainly used to show the connection component; Figure 5 is a partial enlarged view of the structure of an embodiment of the present application, mainly used to show the connecting ring.

[0029] Description of reference numerals: 11. Outer sleeve; 12. Female coupling of outer sleeve; 21. Inner sleeve; 22. Female coupling of inner sleeve; 23. Flow hole; 3. Cover plate; 31. Water injection hole; 4. Driving assembly; 41. Waterproof box; 42. Driving ring; 43. Driving gear ring; 44. Driven gear; 45. Connecting plate; 46. Positioning hole; 47. Rotating rod; 48. Push rod; 49. Fixed plate; 5. Support assembly; 51. Support plate; 6. Connecting assembly; 61. Fixed ring; 62. Connecting block; 63. Connecting rod; 7. Flow guiding assembly; 71. Flow guiding groove; 72. Flow guiding plate; 73. Chain; 74. Connecting ring; 75. Baffle plate. Detailed implementation manners

[0030] The following further describes the present application in detail with reference to Figures 1-5 the accompanying drawings.

[0031] An embodiment of the present application discloses a coaxial sleeve heat exchanger for a geothermal well.

[0032] Referring to Figure 1 and Figure 2 , a coaxial sleeve heat exchanger for a geothermal well includes a plurality of inner sleeves 21 and a plurality of outer sleeves 11. The plurality of outer sleeves 11 are arranged in sequence from top to bottom, and the plurality of inner sleeves 21 are arranged in sequence from top to bottom. The inner sleeves 21 are coaxially arranged inside the outer sleeves 11. At the top of each outer sleeve 11, a female coupling 12 of the outer sleeve is coaxially fixedly connected, and a thread is coaxially provided on the outer wall of the bottom. The bottom of the upper outer sleeve 11 is coaxially inserted into the female coupling 12 of the outer sleeve below it and is threadedly connected thereto. Similarly, at the top of each inner sleeve 21, a female coupling 22 of the inner sleeve is coaxially fixedly connected, and a thread is coaxially provided on the outer wall of the bottom. The bottom of the upper inner sleeve 21 is coaxially inserted into the female coupling 22 of the inner sleeve below it and is threadedly connected thereto. After the outer sleeves 11 are installed one by one through the casing lowering tool on the drilling rig, cement is poured between the outer sleeves 11 and the well wall of the heat exchange well for fixation, and then the inner sleeves 21 are installed one by one through the casing lowering tool.

[0033] Referring to Figure 1 and Figure 2 , in order to enable the heat exchange water source to circulate between the annular space between the inner and outer sleeves and the inside of the inner sleeve 21, the bottom of the lowermost inner sleeve 21 is not provided with a thread, but is evenly provided with a plurality of flow holes 23, so that the water can flow into the inner sleeve 21 after heat exchange in the annular space between the inner and outer sleeves, and then is pumped to the ground by an external circulation pump for use. To prevent foreign objects from entering the annular space between the inner and outer sleeves, a cover plate 3 is welded between the female coupling 12 of the uppermost outer sleeve and the female coupling 22 of the inner sleeve. A water injection hole 31 is provided at the top of the cover plate 3, so as to facilitate injecting the heat exchange water source between the inner and outer sleeves.

[0034] Reference Figure 2 , a plurality of support assemblies 5 are uniformly arranged on the inner sleeve 21 along its circumferential direction. In this embodiment, the support assemblies 5 are arranged in four groups. A driving assembly 4 is also provided on the inner sleeve 21. The driving assembly 4 is used to drive the support assemblies 5 to open. A connecting assembly 6 is further provided at the bottom of the inner sleeve 21. The connecting assembly 6 is used to connect with the driving assembly 4 on the inner sleeve 21 located below it. When using the casing lowering tool to connect two adjacent inner sleeves 21, the casing lowering tool drives the inner sleeve 21 located above to rotate. When it is screwed into the inner casing female thread 22 on the inner sleeve 21 located below, the inner sleeve 21 located above drives the driving assembly 4 on the inner sleeve 21 located below through the connecting assembly 6 thereon. The driving assembly 4 on the inner sleeve 21 located below then drives the four support assemblies 5 thereon to open and abut against the inner wall of the outer sleeve 11, thereby completing the support of the inner sleeve 21, improving the stability during the installation of the inner sleeve 21 and the stability of the inner sleeve 21 under the impact of water flow when the heat exchanger operates.

[0035] Reference Figure 3 , the driving assembly 4 includes a waterproof box 41 provided at the top of the inner sleeve 21. The waterproof box 41 is coaxially sleeved outside the inner sleeve 21 and is fixedly connected to the inner sleeve 21 at the bottom. A driving gear ring 43 is coaxially sleeved on the inner sleeve 21. The driving gear ring 43 is rotatably connected in the waterproof box 41. A driving ring 42 is coaxially and fixedly connected to the driving gear ring 43. The driving ring 42 is coaxially sleeved outside the inner casing female thread 22 and extends out of the top of the waterproof box 41. Four driven gears 44 are also rotatably connected in the waterproof box 41. The four driven gears 44 are uniformly arranged along the circumferential direction of the driving gear ring 43 and are all meshed with the driving gear ring 43. The driving ring 42 extending out of the top of the waterproof box 41 is fixedly connected with four connecting plates 45. The four connecting plates 45 are uniformly distributed along the circumferential direction of the driving ring 42, and each connecting plate 45 is provided with a positioning hole 46 for connecting with the connecting assembly 6 located above it. To facilitate the hot water source to flow down from the top of the inner and outer sleeves, the top of the waterproof box 41 is inclined towards the direction close to the inner sleeve 21 to guide the flowing water source.

[0036] Reference Figure 3, a rotating rod 47 is coaxially fixedly connected to the bottom of the four driven gears 44. The rotating rod 47 is vertically arranged and passes through the bottom of the waterproof box 41. A plurality of push rods 48 are fixedly connected to each rotating rod 47. The plurality of push rods 48 are arranged equidistantly along the axial direction of the rotating rod 47. In this embodiment, three push rods 48 are arranged. The three push rods 48 on the same rotating rod 47 form a group. The four groups of support assemblies 5 are respectively located between two adjacent rotating rods 47. Each group of push rods 48 is located on the side of the corresponding group of support assemblies 5 away from the inner wall of the outer sleeve 11, and is used to push the support assemblies 5. The push rods 48 are arranged horizontally, one end of the push rods 48 is fixedly connected to the rotating rod 47, and the other end can rotate between the corresponding group of support assemblies 5 and the inner sleeve 21. To facilitate storage of the push rod 48, the push rod 48 is configured to be arc-shaped with the concave surface facing the inner sleeve 21. Before installing the inner sleeve 21, the push rod 48 is rotated so that its free end faces the inner sleeve 21, thereby storing it outside the inner sleeve 21 for easy transportation.

[0037] Reference Figure 3 Four fixing plates 49 are fixedly connected to the bottom surface of the waterproof box 41. The fixing plates 49 are vertically arranged in the length direction. The four fixing plates 49 are evenly distributed along the circumference of the waterproof box 41. Each fixing plate 49 is provided with a corresponding rotating rod 47. The rotating rod 47 is located between the corresponding fixing plate 49 and the inner sleeve 21. A group of supporting components 5 is fixed between two adjacent fixing plates 49. The supporting component 5 includes a plurality of supporting plates 51. The plurality of supporting plates 51 are arranged at equal intervals along the length direction of the fixing plates 49. In this embodiment, the supporting plates 51 are provided in three pieces. The three supporting plates 51 in a group of supporting components 5 and the three push rods 48 in the corresponding group of push rods 48 are provided in one-to-one correspondence. The push rods 48 are located between the corresponding supporting plates 51 and the inner sleeve 21. The top of the supporting plate 51 is rotatably connected between two adjacent fixing plates 49. The bottom of the supporting plate 51 is provided in an arc shape, and the diameter is the same as the inner wall diameter of the outer sleeve 11, so as to fit the inner wall of the outer sleeve 11.

[0038] Reference Figure 2 and Figure 4, the connecting component 6 includes a fixing ring 61 coaxially and fixedly connected to the bottom of the inner sleeve 21. Four connecting blocks 62 are fixedly connected to the fixing ring 61. The four connecting blocks 62 are respectively located below the four rotating rods 47. The four rotating rods 47 are respectively rotatably connected to the tops of the four connecting blocks 62. The four fixing plates 49 are respectively fixedly connected to the corresponding four connecting blocks 62. A connecting rod 63 is threadedly connected to the bottom of each connecting block 62. The connecting rod 63 is axially vertically arranged. The four connecting rods 63 are respectively arranged in one-to-one correspondence with the four connecting plates 45 on the inner sleeve 21 below them. The connecting rod 63 is used to be inserted into the positioning holes 46 on the corresponding connecting plates 45. To facilitate the insertion of the connecting rod 63, the bottom of the connecting rod 63 is set to be conical to facilitate insertion into the positioning hole 46. The length of the connecting rod 63 is greater than the distance between the fixing ring 61 and the bottom surface of the inner sleeve 21, so that the connecting rod 63 on the upper inner sleeve 21 can be inserted into the connecting plate 45 on the lower inner sleeve 21 before connecting two adjacent inner sleeves 21. The connecting rod 63 is not installed at the bottom of the lowermost inner sleeve 21 to facilitate placing the lowermost inner sleeve 21 at the bottom of the well.

[0039] When installing the inner sleeve 21, first use the casing lowering tool to lower the inner sleeve 21 without the connecting rod 63 installed at the bottom into the heat exchange well, and make the waterproof box 41 partially expose out of the wellhead. Then use the chuck to clamp the bottom of the waterproof box 41. At this time, it is the first inner sleeve 21. Then the casing lowering tool releases the first inner sleeve 21, and then inner supports the second inner sleeve 21 and places it above the inner sleeve female thread 22 at the top of the first inner sleeve 21. At this time, the worker aligns the four connecting rods 63 at the bottom of the second inner sleeve 21 with the positioning holes 46 on the four connecting plates 45 at the top of the first inner sleeve 21 respectively. Then the drilling rig lowers the second inner sleeve 21, and the four connecting rods 63 at the bottom of the second inner sleeve 21 are respectively inserted into the corresponding positioning holes 46. When the bottom of the second inner sleeve 21 enters the inner sleeve female thread 22 at the top of the first inner sleeve 21, the casing lowering tool drives the second inner sleeve 21 to rotate and gradually descend. At this time, the connecting rod 63 drives the driving ring 42 of the first inner sleeve 21 to rotate, the driving ring 42 drives the driving gear ring 43 to rotate, the driving gear ring 43 drives the four driven gears 44 to rotate, and the four driven gears 44 respectively drive the rotating rods 47 on them to rotate. Each rotating rod 47 drives the three push rods 48 on it to rotate away from the inner sleeve 21, and the three push rods 48 push the bottom of the corresponding support plate 51 to rotate towards the inner wall of the outer sleeve 11. When the bottom of the second inner sleeve 21 is completely screwed into the inner sleeve female thread 22 at the top of the first inner sleeve 21, the bottom of the support plate 51 of the first inner sleeve 21 just rotates to abut against the inner wall of the outer sleeve 11, thus completing the support and positioning of the first inner sleeve 21.

[0040] After completing the connection of the first two inner sleeves 21, loosen the chuck, lower the two inner sleeves 21 until the waterproof box 41 of the second inner sleeve 21 is exposed above the wellhead, then use the chuck to clamp the waterproof box 41 of the second inner sleeve 21, and then use the installation process of the third inner sleeve 21 to open the support plate 51 on the second inner sleeve 21 to complete the support and positioning of the second inner sleeve 21. Repeat this process until the connection of the last two inner sleeves 21 and the opening of the support plate 51 on the penultimate inner sleeve 21 are completed. When the last inner sleeve 21 is lowered into the well, since there is no inner sleeve 21 above, the connecting plate 45 on it can be manually rotated at this time, thereby driving the driving ring 42 to rotate and opening the support plate 51 on it, so as to complete the support and positioning of the last inner sleeve 21. After completing the installation of the last inner sleeve 21, weld the male thread 22 of the uppermost inner sleeve and the male thread 12 of the outer sleeve through the cover plate 3 to complete the fixation of the inner sleeve 21, thereby completing the fixation of the driving assembly 4 and the support assembly 5, and avoiding the influence of water flow impact on the stability of the support assembly 5.

[0041] Refer to Figure 3 , to improve the heat exchange effect between the heat exchange water source and the inner wall of the outer sleeve 11, four groups of flow guiding components 7 are also provided outside the inner sleeve 21. The four groups of flow guiding components 7 are respectively arranged in one-to-one correspondence with the four groups of support components 5, and the flow guiding components 7 are located between the corresponding support components 5 and the inner sleeve 21.

[0042] Refer to Figure 3 and Figure 5, a plurality of diversion grooves 71 are formed in the lower part of the support plate 51. When the support plate 51 is vertically arranged, the length direction thereof is parallel to the length direction of the fixed plate 49, the diversion grooves 71 are arranged along the width direction of the support plate 51, and the plurality of diversion grooves 71 are arranged at equal intervals along the length direction of the support plate 51. The diversion assembly 7 includes three diversion plates 72, which are respectively arranged in one-to-one correspondence with the three support plates 51 in the same support assembly 5. One end of the diversion plate 72 is hinged to the side of the support plate 51 facing the inner sleeve 21, and the hinged end of the diversion plate 72 is located below the diversion groove 71. The other end of the diversion plate 72 is connected to the side of the support plate 51 facing the inner sleeve 21 by two chains 73, and the two chains 73 are respectively located on both sides of the length direction of the support plate 51. Both ends of the chain 73 are sleeved with connecting rings 74, and the two connecting rings 74 are respectively fixedly connected to the support plate 51 and the diversion plate 72. A blocking plate 75 is further arranged on the side of each support plate 51 facing the inner sleeve 21. The blocking plate 75 is fixedly connected between two adjacent fixed plates 49. The blocking plate 75 is located below two adjacent push rods 48, and the blocking plate 75 is vertically arranged. When the support plate 51 is not unfolded, it is vertically arranged between the two fixed plates 49. At this time, the free end of the diversion plate 72 is located above the hinged end and is clamped between the support plate 51 and the blocking plate 75 for easy storage. When the support plate 51 is unfolded, the diversion plate 72 rotates downward due to gravity. When it rotates to the bottom thereof facing the inner sleeve 21 and is inclined, the chain 73 is straightened to fix it at this angle. At this time, a gap is formed between the diversion plate 72 and the support plate 51 below it, and the bottom of the diversion plate 72 is close to the end of the adjacent support plate 51 below it away from the diversion groove 71.

[0043] When the heat exchange water source enters between the inner and outer sleeves, the water flow sliding onto the support plate 51 slides along the inclined direction of the support plate 51 towards the direction close to the inner wall of the outer sleeve 11, so as to increase the contact area with the inner wall of the outer sleeve 11. Then part of the water flow flows from the diversion groove 71 into the diversion plate 72. At the same time, due to the blocking of the blocking plate 75, this part of the water flow flows along the diversion plate 72 to the next support plate 51, and then this process is continuously repeated. Since the water flow needs to pass through the cross-directional guidance of the support plate 51 and the diversion plate 72 to flow to the bottom of the well, the contact time of the water flow with the inner wall of the outer sleeve 11 is prolonged. Therefore, through the diversion assembly 7, the contact area and time of the water flow with the inner wall of the outer sleeve 11 can be increased simultaneously, thereby improving the heat exchange effect of the water flow.

[0044] The implementation principle of a coaxial casing heat exchanger for a geothermal well in an embodiment of this application is as follows: First, an appropriate number of inner casings 21 and outer casings 11 are equipped according to the depth of the heat exchange well. Then, the outer casing 11 is installed. During installation, the first outer casing 11 is lowered into the heat exchange well using a casing lowering tool, and the outer casing female thread 12 is exposed above the wellhead. Then, the outer casing female thread 12 is clamped using a chuck. Then, the casing lowering tool releases the first outer casing 11, and then the second outer casing 11 is internally propped up and placed inside the outer casing female thread 12 of the first outer casing 11. At this time, the casing lowering tool drives the second outer casing 11 to rotate and gradually descend, and stops when it rotates to abut against the first outer casing 11, thus completing the connection of the first two outer casings 11. Then, the chuck is released, and the two outer casings 11 are lowered until the outer casing female thread 12 of the second outer casing 11 is exposed above the wellhead, and the chuck is used for clamping. Then, the third outer casing 11 is connected, and the steps are the same as before. After the connection is completed, it is lowered again, and then the fourth outer casing 11 is installed... Repeat this way until all the outer casings 11 are installed. After the outer casing 11 is installed, cement is poured between the outer casing 11 and the well wall of the heat exchange well for fixation.

[0045] Then, use the casing lowering tool to install the inner casings 21 one by one. The steps for installing the inner casings 21 are the same as those for installing the outer casings 11, so they will not be elaborated here. It should be noted that the first inner casing 21 to be installed must be the one with a flow hole 23 opened at the bottom, and before installing this inner casing 21, the connecting rod 63 at its bottom needs to be unscrewed before installation. During the installation process, except for the uppermost inner casing 21, the support plates 51 on the remaining inner casings 21 are all opened due to the connection with the inner casing 21 above them. The specific process is as follows: When the upper inner casing 21 descends to the inner casing female thread 22 at the top of the lower inner casing 21, at this time, the worker aligns the four connecting rods 63 at the bottom of the upper inner casing 21 with the positioning holes 46 on the four connecting plates 45 at the top of the lower inner casing 21 respectively, and then the drilling rig lowers the upper inner casing 21, and the four connecting rods 63 are respectively inserted into the corresponding positioning holes 46. When the bottom of the upper inner casing 21 enters the inner casing female thread 22 at the top of the lower inner casing 21, the casing lowering tool drives the upper inner casing 21 to rotate and gradually descend. At this time, the connecting rod 63 drives the driving ring 42 of the lower inner casing 21 to rotate, the driving ring 42 drives the driving gear ring 43 to rotate, the driving gear ring 43 drives the four driven gears 44 to rotate, and the four driven gears 44 respectively drive the rotating rods 47 on them to rotate. Each rotating rod 47 drives the three push rods 48 on it to rotate away from the inner casing 21, and the three push rods 48 push the bottom of the corresponding support plate 51 to rotate towards the inner wall of the outer casing 11. When the bottom of the upper inner casing 21 is completely screwed into the inner casing female thread 22 at the top of the lower inner casing 21, the bottom of the support plate 51 of the lower inner casing 21 just rotates to abut against the inner wall of the outer casing 11, thus completing the support and positioning of the lower inner casing 21. For the uppermost inner casing 21, the driving ring 42 needs to be manually rotated to open the support plate 51, and thus the support and positioning of all the inner casings 21 can be completed.

[0046] After both the inner and outer casings are installed, place the cover plate 3 between the inner casing female thread 22 and the outer casing female thread 12 at the top and weld them, thus completing the fixation of the inner casing 21.

[0047] The above are all the preferred embodiments of this application, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A coaxial casing heat exchanger for use in a geothermal well, comprising a plurality of inner casings (21) and a plurality of outer casings (11), wherein the inner casings (21) are coaxially arranged in the outer casing (11), the plurality of inner casings (21) and the plurality of outer casings (11) are arranged in sequence in a vertical direction, the inner casing (21) is coaxially fixedly connected to an inner casing female buckle (22) at the top, a thread is provided on the outer side wall of the bottom, and the outer casing (11) is coaxially fixedly connected to an outer casing female buckle (22) at the top. 12), a thread is provided on the outer side wall of the bottom, the inner casing (21) located at the top is threadedly connected to the inner casing female buckle (22) of the inner casing (21) located at the bottom, the outer casing (11) located at the top is threadedly connected to the outer casing female buckle (12) of the outer casing (11) located at the bottom, and the bottom side wall of the inner casing (21) located at the bottom is not provided with a thread, but is provided with a plurality of flow holes (23), the outer casing (11) is fixed to the wall of the heat exchange well by cement, and is characterized in that: The inner sleeve (21) is provided with a driving assembly (4) and a plurality of groups of support plates (51). The plurality of groups of support plates (51) are arranged along the circumference of the inner sleeve (21). The support plates (51) are rotatable. When the inner sleeve (21) located at the top rotates into the inner sleeve female buckle (22) on the inner sleeve (21) located at the bottom, the driving assembly (4) can drive the plurality of groups of support plates (51) to rotate until they abut against the inner wall of the outer sleeve (11).

2. A coaxial tube heat exchanger for use in a geothermal well according to claim 1, characterized in that: The driving assembly (4) comprises a waterproof box (41), the waterproof box (41) being fixedly connected to the top of the outer wall of the inner sleeve (21), a driving gear ring (43) being rotatably connected inside the waterproof box (41), the driving gear ring (43) being coaxially arranged with the inner sleeve (21), a plurality of driven gears (44) being rotatably connected inside the waterproof box (41), the plurality of driven gears (44) being meshed with the driving gear ring (43), a rotating rod (47) being coaxially fixedly connected to the bottom of each driven gear (44), and a push rod (48) being arranged on each rotating rod (47), and a plurality of groups of driven gears (44) being rotatably connected to the inner sleeve (21) and the driving ring (43) being coaxially arranged with the driving ring (43). The rotating rods (47) are arranged in a one-to-one correspondence with the plurality of groups of support plates (51); the push rods (48) are used to push the support plates (51) to rotate; the top of the driving gear ring (43) is coaxially fixedly connected with a driving ring (42); the driving ring (42) extends out of the top of the waterproof box (41); a connecting plate (45) is arranged on the top of the driving ring (42); except for the inner sleeve (21) located at the bottom, the bottoms of the remaining inner sleeves (21) are all provided with connecting rods (63); a positioning hole (46) is opened on the connecting plate (45); the connecting rod (63) is used to be inserted into the positioning hole (46).

3. A coaxial tube heat exchanger for use in a geothermal well according to claim 2, characterized in that: The support plates (51) are arranged in four groups, and the four groups of support plates (51) are evenly spaced and distributed along the circumference of the inner sleeve (21). Four fixing plates (49) are fixedly connected to the bottom surface of the waterproof box (41). The four fixing plates (49) and the four groups of support plates (51) are cross-arranged along the circumference of the waterproof box (41). The top of the support plate (51) is rotatably connected between two adjacent fixing plates (49). Four rotating rods (47) are also arranged, and the push rod (48) on each rotating rod (47) is located on the side of the corresponding support plate (51) facing the inner sleeve (21).

4. The coaxial casing heat exchanger for use in a geothermal well according to claim 2, characterized in that: Each group of the support plates (51) comprises three support plates (51), and the three support plates (51) are arranged at equal intervals in the vertical direction. Three push rods (48) are also arranged on each rotating rod (47), and the three push rods (48) are used to push the three support plates (51) respectively.

5. The coaxial casing heat exchanger for use in a geothermal well according to claim 3, characterized in that: The free end of the support plate (51) is arranged to be arc-shaped, and its diameter is the same as the diameter of the inner wall of the outer sleeve (11).

6. The coaxial casing heat exchanger for use in a geothermal well according to claim 3, characterized in that: The push rod (48) is arranged in an arc shape with the concave surface facing the inner sleeve (21).

7. The coaxial casing heat exchanger for use in a geothermal well according to claim 4, characterized in that: A plurality of guide grooves (71) are provided at the lower portion of the support plate (51).

8. The coaxial tube heat exchanger for use in a geothermal well according to claim 7, characterized in that: Each support plate (51) is hingedly connected to a guide plate (72) on one side facing the inner sleeve (21); the other end of the guide plate (72) is connected to the support plate (51) via a chain (73); when the support plate (51) abuts against the inner wall of the outer sleeve (11), the guide plate (72) rotates to be located below the guide groove (71), and the bottom of the guide plate (72) is tilted toward the inner sleeve (21).

9. A coaxial tube heat exchanger for use in a geothermal well according to claim 8, characterized in that: A blocking plate (75) is vertically arranged on the side of each support plate (51) facing the inner sleeve (21), and the blocking plate (75) is fixedly connected between two adjacent fixed plates (49). The blocking plate (75) is located below the corresponding push rod (48). When the support plate (51) is in a vertical state, the guide plate (72) rotates so that the free end is located above the hinged end, and the guide plate (72) is located between the support plate (51) and the blocking plate (75).

10. The coaxial casing heat exchanger for use in a geothermal well according to claim 1, characterized in that: A cover plate (3) is welded between the inner sleeve female buckle (22) and the outer sleeve female buckle (12) at the top end, and a water injection port is provided on the cover plate (3).

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