A middle-deep layer geothermal coaxial casing heat exchanger outer casing and a processing method thereof

Abstract

The application discloses a middle-deep layer geothermal coaxial sleeve heat exchanger outer sleeve and a processing method, relates to the technical field of middle-deep layer geothermal development and utilization, and belongs to the coaxial sleeve heat exchanger outer sleeve with a composite structure, which comprises a first outer sleeve and a second outer sleeve connected with each other. The inner side of the first outer sleeve is provided with a vortex generator. The vortex generator comprises a hollow cylinder. A plurality of protrusions and a plurality of flow guide structures are fixedly arranged on the inner wall of the hollow cylinder. A plurality of flaps are fixedly arranged on the upper end of the hollow cylinder, and are used for reliably and simply fixing the vortex generator. The vortex generator is tightly attached to the inner wall of the first outer sleeve. The plurality of protrusions on the surface of the vortex generator can effectively enhance the disturbance of the heat exchange medium and play a role in strengthening heat transfer, and at the same time, the resistance is not significantly increased, so that the heat exchange efficiency is improved. The flow guide structures are arranged at the inlet end of the vortex generator, can guide the fluid into the flow channel of the vortex generator, can reduce the resistance, and can improve the effect of flow disturbance and heat transfer strengthening.

Description

Technical Field

[0001] This invention relates to the field of geothermal development and utilization technology in medium-deep geothermal fields, and more specifically to the outer casing of a coaxial heat exchanger for medium-deep geothermal fields and its processing method. Background Technology

[0002] my country's average geothermal gradient is approximately 3°C per 100 meters. This means that below the isothermal layer, the geothermal temperature increases by about 3°C ​​for every 100 meters of depth. At depths of 1000–4000 meters, the geothermal temperature ranges from approximately 50 to 135°C. While the temperatures of this portion of medium-deep geothermal resources are insufficient for power generation, they can serve as a stable heat source for building heating. Medium-deep geothermal technology is currently the most important technology for developing and utilizing medium-deep geothermal energy. Its principle is based on the geothermal gradient, installing closed heat exchangers at depths of approximately 2000–3000 meters to extract heat from the rock strata for use in building heating, etc. Currently, the coaxial shell heat exchangers used in medium-deep geothermal technology typically have an outer shell made of smooth-walled alloy steel round tubes. The use of these outer shells presents several disadvantages: 1. In heat exchangers with smooth inner walls, fluid turbulence is minimal, and the heat exchange area is only the inner wall area of ​​the round tube, resulting in weak heat exchange medium turbulence, low heat exchange efficiency, and low output power per single medium-deep geothermal heat exchange hole. 2. Some outer shells are designed with structures to increase the heat exchange area, but these structures are generally fixed to the inner wall of the outer shell or prefabricated, increasing processing costs and fluid resistance. 3. The outer shell is usually made of oilfield tubing, which typically has a corrosion resistance lifespan of over 30 years. Therefore, when structures to increase the heat exchange area are fixed to the inner wall of already operational outer shells, heat treatment or chemical processes are often required, which can easily affect the material, structure, and mechanical properties of the outer shell itself. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned technical problems by providing an outer jacket of a medium-deep geothermal coaxial heat exchanger and a processing method thereof, which has the characteristics of enhanced heat exchange and low fluid resistance. In practical use, it does not require changes to the material and processing technology of the existing outer jacket, and the construction and installation process is simple and low in cost.

[0004] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0005] An outer casing for a medium-deep geothermal coaxial shell heat exchanger includes a first outer casing and a second outer casing, both having the same inner and outer diameters. A connecting cylinder is fixedly installed at the upper end of the second outer casing, and the connecting cylinder is inserted into the first outer casing. A vortex generator is installed inside the first outer casing, and the vortex generator includes a hollow cylinder. Multiple protrusions are fixedly installed on the inner wall of the hollow cylinder, and multiple flaps are fixedly installed around the upper end of the hollow cylinder, all located between the first and second outer casings. Multiple flow guiding structures are installed around the outer wall of the hollow cylinder, all located at the inlet end of the vortex generator, and each flow guiding structure includes multiple guide plates located inside the hollow cylinder.

[0006] Preferably, the outer wall of the first outer sleeve is provided with an external thread, and the inner wall of the connecting cylinder is provided with an internal thread that matches the external thread.

[0007] Preferably, the second outer sleeve and the connecting sleeve are manufactured as a single piece.

[0008] Preferably, the lengths of the first outer tube and the second outer tube are both 8-12m, the length of the connecting tube is 150-220mm, and the total length of the multiple sections of the first outer tube and the second outer tube connected by the connecting tube is 2000-3000m.

[0009] Preferably, the vortex generator with the flow guiding structure is made of copper, and the length of the vortex generator is 500-600mm.

[0010] Preferably, the protrusion is elliptical in shape, with a major axis radius of 6-10 mm and a height equal to the minor axis radius of 3-7 mm. The multiple protrusions are arranged in a crisscross pattern along their length.

[0011] Preferably, the guide plate is arc-shaped with a width of 8-12mm and a central angle of 30-60°. Multiple guide plates are evenly arranged around the hollow cylinder.

[0012] A method for processing the outer casing of a medium-deep geothermal coaxial heat exchanger includes the following processing steps:

[0013] 1. Machining the outer casing: The outer casing of the medium-deep geothermal coaxial tube heat exchanger is made of multiple outer casings connected to each other. That is, two outer casings are installed through a connecting cylinder. External threads and internal threads are respectively made on the outer wall of the first outer casing and the inner wall of the connecting cylinder.

[0014] 2. Making the vortex generator: A hollow cylinder is made of copper. The inner wall of the hollow cylinder is stamped to form multiple protrusions and multiple flow guiding structures. During the stamping process, the hollow cylinder is stamped from the outside to the inside to form flow guiding holes. The plate in the hole is pressed upwards and outwards to form a flow guiding plate. The upper end of the hollow cylinder is pressed outwards to form multiple folds around the cylinder.

[0015] 3. Install the vortex generator: Place the vortex generator inside the connecting cylinder. The hollow cylinder is located inside the first outer sleeve. Multiple flaps around the upper end of the hollow cylinder are clamped at the top of the second outer sleeve. The first outer sleeve and the connecting cylinder are threaded together. Thus, the multiple flaps are clamped by the first and second outer sleeves, thereby completing the installation of the vortex generator.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. The outer tube of the coaxial tube heat exchanger has a composite structure. The vortex generator is tightly attached to the inner wall of the outer tube. By locally installing the vortex generator at specific positions on the inner wall of each section of the outer tube, the flow state of the heat exchange medium is changed, its turbulence is enhanced, and the heat transfer is strengthened. The vortex generator has multiple elliptical protrusions on its surface, which are arranged in a crisscross pattern along its length. This vortex generator has low resistance characteristics. In actual use, it can effectively enhance the turbulence of the heat exchange medium without significantly increasing the resistance, thereby improving the heat exchange efficiency.

[0018] 2. The vortex generator is equipped with a flow guiding structure at the inlet end. The flow guide plate can guide the fluid into the flow channel of the vortex generator, which can further reduce resistance and improve the turbulence effect.

[0019] 3. After forming, the vortex generator is in the shape of a hollow cylinder. By setting a fold with the same wall thickness as the outer tube at one end of the hollow cylinder, the vortex generator can be installed directly between the two outer tubes and fixed by the pressure of the two outer tubes. The length of the vortex generator is then determined by segmenting according to the overall length of the outer tube. Segmented installation can locally enhance the turbulence of the fluid and enhance heat transfer. Compared with increasing the heat transfer area across the entire width, it has less resistance and will not significantly increase the power consumption required for fluid drive.

[0020] 4. Compared with the measure of installing the vortex generator in sections on the inner wall of the outer tube with the full-size heat exchange area, the processing cost of the enhanced heat exchange measure can be reduced, and the cost of the enhanced heat exchange measure can be lowered.

[0021] 5. By adding a copper vortex generator with a special structure in some areas, the material and processing technology of the existing outer tube do not need to be changed in actual use. The installation process also adopts a physical installation process without any other heat treatment or chemical process, which can maintain the material, structure and mechanical properties of the outer tube itself, and improve the convenience and safety in actual use.

[0022] 6. By changing the structure of the existing coaxial tube heat exchanger, the vortex generator folding and pressing installation method adopted in this application has the characteristics of simple construction process, easy operation and low cost. Attached Figure Description

[0023] Figure 1 This is a cross-sectional schematic diagram of the present invention;

[0024] Figure 2 yes Figure 1 Schematic diagram at point A;

[0025] Figure 3 This is a schematic diagram of the split structure of the present invention;

[0026] Figure 4 This is a top view of a vortex generator;

[0027] Figure 5 This is a front view of a vortex generator.

[0028] Reference numerals: 1. First outer sleeve; 101. External thread; 2. Second outer sleeve; 3. Connecting cylinder; 301. Internal thread; 4. Vortex generator; 401. Hollow cylinder; 402. Protrusion; 403. Fold; 404. Guide hole; 405. Guide plate. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0030] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Please see Figures 1-5The present invention provides the following technical solution: an outer sleeve for a medium-deep geothermal coaxial shell heat exchanger, comprising a first outer sleeve 1 and a second outer sleeve 2, wherein the inner and outer diameters of the first outer sleeve 1 and the second outer sleeve 2 are the same, and a connecting cylinder 3 is fixedly provided at the upper end of the second outer sleeve 2. The second outer sleeve 2 and the connecting cylinder 3 are integrally manufactured, and the connecting cylinder 3 and the first outer sleeve 1 are inserted together. The outer wall of the first outer sleeve 1 is provided with an external thread 101, and the inner wall of the connecting cylinder 3 is provided with an internal thread 301 that matches the external thread 101. A vortex generator 4 is provided inside the tube 1. The vortex generator 4 includes a hollow cylinder 401. Multiple protrusions 402 are fixedly provided on the inner wall of the hollow cylinder 401. Multiple flaps 403 are fixedly provided around the upper end of the hollow cylinder 401. The multiple flaps 403 are all located between the first outer sleeve 1 and the second outer sleeve 2. Multiple flow guiding structures are provided around the outer wall of the hollow cylinder 401. The multiple flow guiding structures are all located at the inlet end of the vortex generator. The flow guiding structures include multiple flow guiding plates 405 located inside the hollow cylinder 401.

[0032] In this embodiment: the outer casing of the medium-deep geothermal coaxial shell heat exchanger is 2000-3000m long and is made of multiple interconnected outer casings. The first outer casing 1 is threaded to the inner wall of the connecting cylinder 3. In actual use, the lengths of the first outer casing 1 and the second outer casing 2 are both 8-12m. In actual use, the vortex generator 4 is partially installed at the beginning of each section of the outer casing. The length of the vortex generator 4 is 560mm, and the length of the connecting cylinder 3 is 200mm. The vortex generator 4 operates within the annular confined space between the inner and outer casings, under the condition that the fluid velocity within the annulus is 0.6-1.5m / s. The vortex generator effectively increases fluid disturbance, thereby enhancing heat transfer. Six arc-shaped flow guide structures are evenly arranged circumferentially in the inlet section of the vortex generator. The central angle of the arc-shaped flow guide structures is 30° and the height is 8mm. The protrusions 402 of the vortex generator 4 are elliptical in shape, with a major axis radius of 8mm and a minor axis radius of 5mm. The multiple protrusions 402 are arranged in a crisscross pattern along their length. Multiple arc-shaped flow guide plates 405 can guide the fluid to the position between the multiple protrusions 402, thereby reducing the resistance experienced by the fluid and achieving increased disturbance without significantly increasing resistance and power consumption.

[0033] A method for processing the outer casing of a medium-deep geothermal coaxial heat exchanger includes the following processing steps:

[0034] 1. Processing the outer casing: The outer casing of the medium-deep geothermal coaxial shell heat exchanger is made of multiple outer casings connected to each other. That is, two outer casings are installed through the connecting cylinder 3. External threads 101 and internal threads 301 are respectively made on the outer wall of the first outer casing 1 and the inner wall of the connecting cylinder 3.

[0035] II. Manufacturing the vortex generator: A hollow cylinder 401 is made of copper. The inner wall of the hollow cylinder 401 is formed by stamping multiple protrusions 402 and multiple flow guiding structures. During the stamping process, the hollow cylinder 401 is stamped from the outside to the inside to form flow guiding holes 404. The plate in the hole is pressed upwards and inwards to form a flow guiding plate 405. The upper end of the hollow cylinder 401 is pressed outwards to form multiple flaps 403 around the cylinder.

[0036] 3. Install the vortex generator: Place the vortex generator 4 inside the connecting cylinder 3. The hollow cylinder 401 is located inside the first outer sleeve 1. Multiple flaps 403 around the upper end of the hollow cylinder 401 are clamped at the top of the second outer sleeve 2. The first outer sleeve 1 and the connecting cylinder 3 are threaded together, and the multiple flaps 403 are clamped by the first outer sleeve 1 and the second outer sleeve 2, thereby completing the installation of the vortex generator 4.

[0037] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An outer casing for a medium-deep geothermal coaxial shell heat exchanger, comprising a first outer casing (1) and a second outer casing (2), wherein the inner and outer diameters of the first outer casing (1) and the second outer casing (2) are the same, and a connecting cylinder (3) is fixedly provided at the upper end of the second outer casing (2), wherein the connecting cylinder (3) and the first outer casing (1) are inserted into each other, characterized in that: A vortex generator (4) is provided on the inner side of the first outer tube (1). The vortex generator (4) includes a hollow cylinder (401). A plurality of protrusions (402) are fixedly provided on the inner wall of the hollow cylinder (401). A plurality of flaps (403) are provided around the upper end of the hollow cylinder (401). The plurality of flaps (403) are located between the first outer tube (1) and the second outer tube (2). A plurality of flow guiding structures are provided around the outer wall of the hollow cylinder (401). The plurality of flow guiding structures are located at the inlet end of the vortex generator (4). The flow guiding structure includes a plurality of flow guiding plates (405) located inside the hollow cylinder (401).

2. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The outer wall of the first outer sleeve (1) is provided with an external thread (101), and the inner wall of the connecting cylinder (3) is provided with an internal thread (301) that matches the external thread (101).

3. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The second outer sleeve (2) and the connecting sleeve (3) are manufactured as a single piece.

4. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The lengths of the first outer tube (1) and the second outer tube (2) are both 8-12m, the length of the connecting tube (3) is 150-220mm, and the total length of the multiple sections of the first outer tube (1) and the second outer tube (2) connected by the connecting tube (3) is 2000-3000m.

5. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The vortex generator (4) is made of copper.

6. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The length of the vortex generator (4) is 500-600mm.

7. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The protrusion (402) is elliptical in shape, with a major axis radius of 6-10 mm and a height of 3-7 mm, which is the minor axis radius of the ellipse.

8. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The plurality of protrusions (402) are arranged in a cross pattern along the length direction.

9. The outer casing of a medium-deep geothermal coaxial heat exchanger according to claim 1, characterized in that: The guide plate (405) is arc-shaped with a width of 8-12mm and a central angle of 30-60°. Multiple guide plates (405) are evenly arranged around the hollow cylinder (401).

10. A method for processing the outer casing of a medium-deep geothermal coaxial shell heat exchanger, characterized in that, The processing steps include the following:

1. Processing the outer casing: The outer casing of the medium-deep geothermal coaxial shell heat exchanger is made of multiple outer casings connected to each other. That is, two outer casings are installed through a connecting cylinder (3). External threads (101) and internal threads (301) are made on the outer wall of the first outer casing (1) and the inner wall of the connecting cylinder (3) respectively. II. Making the vortex generator: A hollow cylinder (401) is made of copper. The inner wall of the hollow cylinder (401) is made of multiple protrusions (402) and multiple flow guiding structures by stamping. During the stamping process, the hollow cylinder (401) is stamped from the outside to the inside to form flow guiding holes (404). The plate in the hole is pressed upwards and inwards to form a flow guiding plate (405). The upper end of the hollow cylinder (401) is pressed outwards to form multiple folds (403) around the cylinder.

3. Install the vortex generator: Place the vortex generator (4) inside the connecting cylinder (3). The hollow cylinder (401) is located inside the first outer sleeve (1). Multiple flaps (403) around the upper end of the hollow cylinder (401) are clamped at the top of the second outer sleeve (2). The first outer sleeve (1) and the connecting cylinder (3) are threaded together. Thus, the multiple flaps (403) are clamped by the first outer sleeve (1) and the second outer sleeve (2), thereby completing the installation of the vortex generator (4).

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