Modular medium-deep geothermal heat extraction device

Abstract

A modular medium-deep geothermal heat extraction device, comprising a sleeve and a surface circulation assembly connected to the sleeve. The sleeve is inserted into the surface; a bottom pipe, a plurality of heat extraction pipes, and a plurality of thermal insulation pipes are sequentially arranged in the sleeve from the deepest position outward; the bottom pipe, the heat extraction pipes, and the thermal insulation pipes are each composed of outer pipes and inner pipes which are coaxial; after the plurality of outer pipes are fitted, a cold water channel is formed between the inner pipes and the outer pipes; after the plurality of inner pipes are fitted, a hot water channel is formed inside the inner pipes; the cold water channel is communicated with the hot water channel inside the bottom pipe; and the cold water channel and the hot water channel are connected to the surface circulation assembly. The sleeve of the modular medium-deep geothermal heat extraction device uses a modular design, and a plurality of modules are separately transported to a construction site for assembly, so that production and transportation costs can be saved; and according to different stratum conditions, different numbers of modules can be selected for arrangement, so that the application is more flexible.

Description

A modular medium-deep geothermal heat extraction device

[0001] This application claims priority to Chinese Patent Application No. 202410941196.8, filed on July 12, 2024, entitled "A Modular Medium-Deep Geothermal Heat Extraction Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of geothermal technology, and more specifically to a modular medium-deep geothermal heat extraction device. Background Technology

[0003] Geothermal energy is a clean and low-carbon energy source. Its rational utilization can provide clean heating as a substitute for electricity in winter and contribute to air pollution control. Traditional geothermal energy utilization often involves extracting water and discharging the wastewater. This method leads to thermal pollution, damages the soil, and reduces underground reservoir pressure and water levels, hindering the sustainable development of medium-deep geothermal energy.

[0004] To address the problems associated with traditional geothermal energy utilization methods, geothermal buried pipe technology has emerged in recent years, offering a smaller footprint and greater environmental friendliness. This technology involves inserting a casing into the rock strata. A circulating pump draws heat exchange fluid from the surface into the casing, where it is heated through heat exchange between the casing's outer wall and the rock strata. The heated fluid is then circulated back into the surface system for reuse as a heat source. This technology eliminates the need to extract groundwater during the heat exchange process, preventing groundwater loss and pollution, and avoiding the difficulties of reinjection and groundwater penetration associated with traditional methods.

[0005] Existing geothermal buried pipe technology has several problems during installation: the inner pipe of existing geothermal casing uses insulated oil pipe, and the outside of the insulated oil pipe needs to be threaded, resulting in high manufacturing costs; the existing geothermal casing is time-consuming and labor-intensive to assemble, and needs to be transported after assembly, resulting in high production and transportation costs; the casing needs to be threaded using a torque wrench during the well running process, which further increases time and labor costs; there is no limiting device for the inner pipe during installation, which makes the inner pipe prone to collision with the outer pipe, increasing construction risks.

[0006] In summary, the existing geothermal buried pipe solution has many shortcomings and there is considerable room for improvement.

[0007] Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a modular medium-deep geothermal heat extraction device, which adopts a modular design, sets up a connecting device and an internal limiting device, and pre-installs the inner and outer pipes of each module through the limiting device. At the construction site, multiple modules are assembled and lowered into the well through the connecting device to facilitate transportation, improve installation efficiency, and reduce construction risks.

[0009] To achieve the above objectives, the present invention provides a modular medium-deep geothermal heat extraction device, comprising a casing and a surface circulation assembly connected to the casing. The casing is inserted into the ground surface, and from the deepest point outwards, a bottom pipe, several heat extraction pipes, and several insulation pipes are arranged sequentially. The bottom pipe, the heat extraction pipes, and the insulation pipes are all composed of coaxial outer and inner pipes. After the several outer pipes are joined together, a cold water channel is formed between the inner pipe and the outer pipes. After the several inner pipes are joined together, a hot water channel is formed inside. The cold water channel and the hot water channel are connected inside the bottom pipe and are connected to the surface circulation assembly.

[0010] Preferably, the outer tube is internally connected to a plurality of limiting blocks, and the limiting blocks surround and connect to the outer wall of the inner tube.

[0011] Preferably, the outer tube includes a coupling, a sealing thread, and an oil casing. The sealing thread is present on the outer sides of both ends of the oil casing. The two oil casings that are joined together are connected by the coupling surrounding the sealing thread.

[0012] Preferably, the outer tube of the insulation pipe is wrapped with a heat insulation interlayer, which is made of two coaxial steel pipes welded together, and the two coaxial steel pipes are filled with air-filled gel.

[0013] Preferably, a bottom plug is fixedly installed at the bottom of the bottom pipe, and the bottom plug seals the bottom end of the bottom pipe.

[0014] Preferably, the bottom end of the well plug is ellipsoidal.

[0015] Preferably, the inner tube includes a sealing device and a heat-insulating oil pipe, the limiting block is connected to the outside of the heat-insulating oil pipe, the sealing device is fixedly connected to the top end of the heat-insulating oil pipe, and the two heat-insulating oil pipes that are joined together are connected through the sealing device.

[0016] Preferably, the sealing device includes an upper interlayer and a lower interlayer, the upper interlayer and the lower interlayer are fixedly connected, the upper interlayer has an upper cavity inside, the lower interlayer has a lower cavity inside, the upper cavity and the lower cavity communicate with each other, and a sealing ring is provided at the bottom of the upper cavity.

[0017] Preferably, the top end of the lower heat-insulating oil pipe is inserted into the lower cavity, and the heat-insulating oil pipe is welded and fixedly connected to the lower interlayer; when the upper heat-insulating oil pipe is inserted downward into the upper cavity, it squeezes the sealing ring downward.

[0018] Compared with existing technologies, the advantages of the modular medium-deep geothermal heat extraction device disclosed in this invention are as follows: the casing of the modular medium-deep geothermal heat extraction device adopts a modular design, with multiple modules transported separately to the construction site for assembly, which can save production and transportation costs. Furthermore, different numbers of modules can be selected for deployment according to different formation conditions, making the application more flexible. The insulated oil pipe of the modular medium-deep geothermal heat extraction device does not require thread processing, which helps reduce manufacturing costs. A limiting device is installed between the inner and outer pipes of the modular medium-deep geothermal heat extraction device to prevent collisions between the inner and outer pipes during well running and to prevent shaking of the inner pipe after installation, ensuring long-term safe operation. The casing of the modular medium-deep geothermal heat extraction device does not require a torque converter during well running, reducing labor costs and operation time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 shows a schematic diagram of a modular medium-deep geothermal heat extraction device according to the present invention.

[0021] Figure 2 shows a schematic diagram of the heat extraction pipe of a modular medium-deep geothermal heat extraction device according to the present invention.

[0022] Figure 3 shows a schematic diagram of the insulation pipe of a modular medium-deep geothermal heat extraction device according to the present invention.

[0023] Figure 4 shows a schematic diagram of the bottom pipe structure of a modular medium-deep geothermal heat extraction device according to the present invention.

[0024] Figure 5 shows a schematic diagram of the sealing device of a modular medium-deep geothermal heat extraction device according to the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] As shown in Figure 1, this application discloses a modular medium-deep geothermal heat extraction device, comprising a casing and a surface circulation assembly connected to the casing. The casing is inserted into the ground surface. From the deepest point outwards, the casing contains a bottom pipe 3, several heat extraction pipes 2, and several insulation pipes 1. Each of the bottom pipe 3, heat extraction pipes 2, and insulation pipes 1 consists of coaxial outer pipes 6 and inner pipes 7. After the outer pipes 6 are joined together, a cold water channel 8 is formed between the inner pipes 7 and the outer pipes 6. After the inner pipes 7 are joined together, a hot water channel 9 is formed inside. The cold water channel 8 and the hot water channel 9 are connected inside the bottom pipe 3 and are connected to the surface circulation assembly. Geothermal energy is used to heat the heat exchange fluid, and the heated heat exchange fluid is circulated back to the surface assembly for use as a heat source. The bottom pipe 3, heat extraction pipes 2, and insulation pipes 1 are manufactured separately as multiple modules for transportation and assembly at the construction site, which can save production and transportation costs. Furthermore, different numbers of wooden blocks can be selected for deployment according to different geological conditions, making the application more flexible.

[0027] The surface circulation assembly includes a circulation pump 4 and a heat pump unit 5. The outlet of the circulation pump 4 is connected to the inlet of the heat pump unit 5. The inner pipe 7 of the uppermost insulation pipe 1 is connected to the inlet of the circulation pump 4, and the outer pipe 6 of the uppermost insulation pipe 1 is connected to the outlet of the heat pump unit 5. The circulation pump 4 realizes water circulation within the casing, and the heat pump unit 5 realizes the utilization of thermal energy.

[0028] Referring to Figure 2, several limiting blocks 73 are connected inside the outer pipe 6 of the bottom pipe 3, the heat-extracting pipe 2, and the insulation pipe 1, and the limiting blocks 73 surround the outer wall of the inner pipe 7. The limiting blocks 73 fix the inner pipe 7 and the outer pipe 6, thus forming a modular bottom pipe 3, heat-extracting pipe 2, and insulation pipe 1. The limiting blocks 73 are preferably made of steel to reduce resistance to water flow.

[0029] The outer tube 6 includes a coupling 61, a sealing thread 62, and an oil casing 63. Both ends of the oil casing 63 have sealing threads 62 on their outer sides. The two oil casings 63 that are joined together are connected by the coupling 61 wrapped around the sealing threads 62. The upper and lower connected outer tubes 6 can be quickly installed using the coupling 61 without the need for special equipment, which helps to improve installation efficiency and reduce installation costs.

[0030] The inner tube 7 includes a sealing device 71, a heat-insulating oil pipe 72, and a sealing ring 74. A limiting block 73 is connected to the outside of the heat-insulating oil pipe 72. The sealing device 71 is fixedly connected to the top end of the heat-insulating oil pipe 72. The two heat-insulating oil pipes 72 are connected by the sealing device 71 and the sealing ring. The heat-insulating oil pipe 72 is a heat-insulating pipe that keeps the internal hot water warm.

[0031] Referring to Figure 3, the outer pipe 6 of the insulation pipe 1 is wrapped with a heat insulation jacket 11. The heat insulation jacket 11 is made of two coaxial steel pipes welded together, and the two coaxial steel pipes are filled with aerogel 12. The heat insulation jacket 11 forms an insulation layer on the outside of the insulation pipe 1, preventing the temperature near the ground surface from interfering with the temperature inside the casing and improving the thermal energy utilization rate.

[0032] Referring to Figure 4, a bottom plug 31 is fixedly installed at the bottom of the bottom pipe 3, sealing the bottom end of the bottom pipe 3. Preferably, the bottom end of the bottom plug 31 is ellipsoidal to reduce the friction between the bottom plug 51 and the well wall during well lowering, thereby improving the convenience and efficiency of well lowering operations.

[0033] Referring to Figure 5, the sealing device 71 includes an upper interlayer 711 and a lower interlayer 712. The upper interlayer 711 and the lower interlayer 712 are fixedly connected. The upper interlayer 711 has an upper cavity 713 inside, and the lower interlayer 712 has a lower cavity 714 inside. The upper cavity 713 and the lower cavity 714 are in communication. A sealing ring 74 is installed at the bottom of the upper cavity 713. The top end of the heat-insulating oil pipe 72 is inserted into the lower cavity 713, and the heat-insulating oil pipe 72 is welded and fixed to the lower interlayer 712. When the upper heat-insulating oil pipe 72 is inserted downward into the upper cavity 713, it presses the sealing ring 74 downward, thereby achieving a sealed connection between the upper and lower heat-insulating oil pipes 72. Preferably, both the upper interlayer 711 and the lower interlayer 712 are tubular structures, and the inner diameter of the upper interlayer 711 is larger than the inner diameter of the lower interlayer 712, which facilitates the insertion of the upper heat insulation oil pipe 72 without the need for precise alignment.

[0034] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A modular medium-deep geothermal heat extraction device, characterized in that, The device includes a casing and a surface circulation assembly connected to the casing. The casing is inserted into the ground surface. From the deepest point outwards, the casing has a bottom pipe, several heat-extracting pipes, and several insulation pipes arranged sequentially. The bottom pipe, the heat-extracting pipes, and the insulation pipes are all composed of coaxial outer and inner pipes. After the several outer pipes are joined together, a cold water channel is formed between the inner pipe and the outer pipe. After the several inner pipes are joined together, a hot water channel is formed inside. The cold water channel and the hot water channel are connected inside the bottom pipe. The cold water channel and the hot water channel are connected to the surface circulation assembly.

2. The modular medium-deep geothermal heat extraction device as described in claim 1, characterized in that, The outer tube is internally connected to several limiting blocks, and the limiting blocks surround and connect to the outer wall of the inner tube.

3. The modular medium-deep geothermal heat extraction device as described in claim 1, characterized in that, The outer tube includes a coupling, a sealing thread, and an oil casing. Both ends of the oil casing have the sealing thread. The two oil casings that are joined together are connected by the coupling surrounding the sealing thread.

4. The modular medium-deep geothermal heat extraction device as described in claim 1, characterized in that, The outer tube of the insulation pipe is wrapped with a heat insulation interlayer, which is made of two coaxial steel pipes welded together, and the two coaxial steel pipes are filled with air-filled gel.

5. The modular medium-deep geothermal heat extraction device as described in claim 1, characterized in that, A bottom plug is fixedly installed at the bottom of the bottom pipe, and the bottom plug seals the bottom end of the bottom pipe.

6. The modular medium-deep geothermal heat extraction device as described in claim 5, characterized in that, The bottom of the well plug is ellipsoidal.

7. The modular medium-deep geothermal heat extraction device as described in claim 2, characterized in that, The inner tube includes a sealing device and a heat-insulating oil pipe. The limiting block is connected to the outside of the heat-insulating oil pipe. The sealing device is fixedly connected to the top end of the heat-insulating oil pipe. The two heat-insulating oil pipes that are joined together vertically are connected through the sealing device.

8. The modular medium-deep geothermal heat extraction device as described in claim 7, characterized in that, The sealing device includes an upper interlayer and a lower interlayer, the upper interlayer and the lower interlayer are fixedly connected, the upper interlayer has an upper cavity inside, the lower interlayer has a lower cavity inside, the upper cavity and the lower cavity are in communication, and a sealing ring is provided at the bottom of the upper cavity.

9. The modular medium-deep geothermal heat extraction device as described in claim 8, characterized in that, The top end of the lower heat-insulating oil pipe is inserted into the lower cavity, and the heat-insulating oil pipe is welded and fixedly connected to the lower interlayer; when the upper heat-insulating oil pipe is inserted downward into the upper cavity, it squeezes the sealing ring downward.

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