Heat preservation and heat exchange structure for middle-deep layer geothermal well

Abstract

The utility model discloses a heat preservation and heat exchange structure for a middle-deep layer geothermal well, which belongs to the technical field of geothermal heat supply equipment and comprises a plurality of groups of geothermal pipes arranged in the geothermal well, each geothermal pipe comprises an inner pipe and an outer pipe which are nested, an annular space for heat exchange media to flow is formed between the outer pipe and the inner pipe, the inner pipe adopts a heat preservation pipe, and the outer pipe adopts a heat exchange pipe. The geothermal well extends downwards from a well mouth and comprises a first section located on a variable-temperature layer and a second section located on a constant-temperature layer and a warming layer, the outer pipe located in the first section is provided with a first heat preservation layer, the geothermal pipe located in the second section is provided with a supporting plate, the supporting plate is arranged between the inner pipe and the outer pipe, and the supporting plate extends in the axial direction of the geothermal pipe. The supporting plates are evenly distributed in the circumferential direction of the inner pipe. The supporting plate is arranged in the geothermal pipe of the deep geothermal well, so that the structural strength of the geothermal pipe is improved, and the risk of deformation of the geothermal pipe is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of geothermal heating equipment, and particularly relates to a heat preservation and heat exchange structure used for a medium-deep geothermal well. Background Art

[0002] The medium-deep non-interference geothermal technology, which is characterized by "closed heat exchange in the well, heat extraction without water extraction", is a non-hydrothermal extraction method currently widely used. It uses mechanical drilling to drill to a certain depth underground, injects softened water as a circulating working fluid into the heat exchanger, and extracts the heat energy in the rock and soil layer for heating through heat conduction.

[0003] In existing geothermal wells, casing is generally used as the heat extraction pipeline. As the depth of the geothermal well increases, the pressure on the casing is gradually increasing. The existing casing structure often limits the depth of its entry into the geothermal well, and the pipeline is prone to deformation during installation and use. Utility Model Content

[0004] The purpose of the utility model is to provide a heat preservation and heat exchange structure for medium-deep geothermal wells, aiming to solve the problems existing in the prior art in the above-mentioned background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A thermal insulation heat exchange structure for a medium-deep geothermal well, comprising a plurality of groups of geothermal pipes arranged in the geothermal well, wherein the geothermal pipes comprise nested inner and outer pipes, an annulus for the flow of heat exchange medium is formed between the outer and inner pipes, the inner pipe is a thermal insulation pipe, the geothermal well extends downward from the wellhead and comprises a first section located in a variable temperature layer, and a second section located in a constant temperature layer and a warming layer, the outer pipe located in the first section is provided with a first thermal insulation layer, and the geothermal pipe located in the second section is provided with a support plate, the support plate is arranged between the inner and outer pipes, the support plate extends axially along the geothermal pipe, and the support plate is evenly arranged around the circumference of the inner pipe.

[0007] Furthermore, the support plate is made of heat-conducting material.

[0008] Furthermore, the number of support plates in each group of geothermal pipes increases with the depth of the geothermal well.

[0009] Furthermore, the inner tube has a second insulation layer, which includes a hollow chamber, and a support member and insulation material arranged in the hollow chamber. The support member is an annular partition, which is evenly arranged along the length direction of the inner tube, and the insulation material is aerogel.

[0010] Furthermore, the support plate is made of aluminum alloy.

[0011] Furthermore, the first thermal insulation layer is made of rigid polyurethane foam.

[0012] Compared with the shortcomings and deficiencies of the prior art, the utility model has the following beneficial effects.

[0013] 1. The utility model provides a thermal insulation and heat exchange structure for medium-deep geothermal wells. A plurality of interconnected groups of geothermal pipes are arranged in the geothermal well. The geothermal well is divided into a first section and a second section extending from the wellhead to the deep layer. The outer pipe of the geothermal pipe located in the first section is provided with a first thermal insulation layer, which is beneficial to maintaining the temperature of the heat exchange medium stable. The geothermal pipe located in the second section is provided with a support plate between the inner pipe and the outer pipe. The support plate is used to assist in supporting the outer pipe, which is beneficial to improving the overall structural strength of the thermal insulation and heat exchange structure and reducing the risk of deformation of the geothermal pipe.

[0014] 2. The support plate is made of heat-conducting material, and as the depth of the geothermal well increases, the number of support plates in the geothermal pipe gradually increases. The support plate increases the heat exchange area, which is beneficial to the full heat exchange of the heat exchange medium and improves the heat exchange efficiency. As the number of support plates increases, the structural strength of the outer pipe gradually increases, further improving the support stability.

[0015] 3. The inner tube has a second thermal insulation layer, which includes a hollow chamber. A support and thermal insulation material are arranged in the hollow chamber. The support is an annular partition evenly arranged along the length direction of the inner tube. The hollow chamber is filled with thermal insulation material. The thermal insulation material is aerogel. The aerogel is combined with the annular partition to ensure the thermal insulation effect and reduce the heat loss during the reflux heating process of the heat exchange medium. At the same time, the structure has a certain supporting capacity, which is conducive to ensuring the structural strength of the inner tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a thermal insulation and heat exchange structure used for a medium-deep geothermal well in the utility model.

[0017] Figure 2 It is a schematic diagram of the internal structure of a group of geothermal pipes in the utility model.

[0018] Figure 3 It is a structural schematic diagram of a support plate arranged between an inner tube and an outer tube in the utility model.

[0019] Figure 4 It is a structural schematic diagram of a plurality of groups of support plates arranged between the inner tube and the outer tube in the utility model.

[0020] In the figure: 1-geothermal well; 2-outer pipe; 3-inner pipe; 4-annulus; 5-first insulation layer; 6-second insulation layer; 7-first section; 8-second section; 9-connector; 10-support plate; 11-support member; 12-insulation material. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0022] Reference Figure 1 A heat preservation and heat exchange structure for a medium-deep geothermal well includes an outer tube 2 and an inner tube 3 arranged in a geothermal well 1. The inner tube 3 is arranged inside the outer tube 2, and an annulus 4 is formed between the inner tube 3 and the outer tube 2. A heat exchange medium flows through the annulus 4 to the deep layer of the geothermal well 1 for heat exchange, flows into the inner tube 3 along the end of the inner tube 3 located in the geothermal well 1, and flows toward the wellhead of the geothermal well 1 through the inner tube 3, and finally the heat exchange medium is extracted for heat supply.

[0023] The geothermal well 1 extends downward from the wellhead and is divided into the first section 7 and the second section 8. The first section 7 geothermal well 1 is in the geothermal variable temperature layer. The geothermal heat is greatly affected by the environment and geographical location, and the geothermal temperature distribution varies greatly. The first insulation layer 5 is set on the outside of the outer pipe 2 of the first section 7 geothermal well 1. The first insulation layer 5 blocks the heat exchange of the heat exchange medium to ensure the stability of the heat exchange medium temperature. The first insulation layer 5 uses hard polyurethane foam. The hard polyurethane foam has good thermal insulation performance and can provide certain support, which is conducive to improving the stability of the shallow structure of the geothermal well 1; the second section 8 geothermal well 1 is in the geothermal constant temperature and warming layer. As the depth of the geothermal well 1 increases, the geothermal temperature gradually rises, and the heat exchange medium exchanges heat with the outer geothermal source through the outer pipe 2, and the temperature of the heat exchange medium gradually rises.

[0024] Reference Figure 2 , the inner tube 3 and the outer tube 2 nested within a certain length form a group of geothermal pipes. Multiple groups of geothermal pipes need to be placed in the geothermal well 1. Adjacent geothermal pipes are connected by connectors 9. The connectors 9 respectively conduct the adjacent outer tubes 2 and the adjacent inner tubes 3 to facilitate the flow of heat exchange medium. The connectors 9 and the geothermal pipes are connected by welding. In a group of geothermal pipes, a support plate 10 is arranged between the outer tube 2 and the inner tube 3. The support plate 10 extends along the axial direction of the geothermal pipe. The two sides of the support plate 10 are respectively vertically connected to the outer tube 2 and the inner tube 3. Multiple support plates 10 are evenly arranged around the inner tube 3. Near the position of the connector 9, the connection side of the support plate 10 and the inner tube 3 is separated from the inner tube 3 and gradually approaches the side of the outer tube 2 to form a streamlined transition. When the heat exchange medium in the adjacent annulus 4 flows, the heat exchange medium passes through the connector 9, which facilitates the rapid diversion of the heat exchange medium.

[0025] The support plate 10 is made of heat-conducting material. Since the support plate 10 is connected to the outer tube 2, the support plate 10 can be used to transfer heat to the heat exchange medium, thereby increasing the heat exchange area, thereby improving the heat exchange efficiency of the heat exchange medium. At the same time, the support plate 10 is used to assist in supporting the outer tube 2 to improve the overall structural strength of the outer tube 2. As the depth of the geothermal well 1 increases, the pressure outside the outer tube 2 rises. The support plate 10 is preferably arranged on the geothermal pipe located in the second section 8 of the geothermal well 1, which is beneficial to improving the stability of the support structure of the outer tube 2. The support plate 10 is preferably made of aluminum alloy material, which has good thermal conductivity and structural strength.

[0026] The number of support plates 10 gradually increases with the increase in the depth of the geothermal well 1 in the second section 8. The number of support plates 10 in each group of geothermal pipes can be adjusted according to the geothermal temperature and is not limited here. On the one hand, the increase in the number of support plates 10 is conducive to adapting to the increase in pressure due to the increase in the depth of the geothermal well 1, thereby providing reliable support. On the other hand, the increase in the number of support plates 10 is conducive to increasing the heat exchange area, thereby improving the heat exchange efficiency.

[0027] The inner tube 3 is provided with a second insulation layer 6, which includes a hollow chamber, in which a support member 11 and an insulation material 12 are provided, wherein the support member 11 is an annular partition having a certain thickness to improve the supporting performance of the support member 11, and the insulation material 12 is filled between adjacent annular partitions. In a group of geothermal pipes, a plurality of annular partitions are evenly arranged along the length direction of the inner tube 3 to improve the supporting performance of the inner tube 3. The annular partition is made of insulation material, and the insulation material 12 is made of aerogel. The aerogel has good insulation performance and a certain structural strength, so that the inner tube 3 has good support and insulation capabilities.

[0028] When the heat-insulating heat-exchanging structure for medium-deep geothermal wells is in use, the heat exchange medium flows to the deep layer of the geothermal well 1 through the annulus 4. The geothermal well 1 located in the first section 7 temperature-changing layer reduces the heat exchange between the heat exchange medium and the outside of the geothermal well 1 under the action of the first insulation layer 5, so that the temperature of the heat exchange medium is stabilized. As the heat exchange medium flows to the deeper second section 8 geothermal well 1, the second section 8 geothermal well 1 is in the geothermal constant temperature layer and the warming layer. As the depth of the geothermal well 1 increases, the geothermal temperature gradually rises. The geothermal pipe located in the second section 8 geothermal well 1 is provided with a support plate 10, and the support plate 10 assists in supporting the outer pipe 2. At the same time, the heat exchange area is increased by the support plate 10, the heat exchange efficiency and the support stability of the outer pipe 2 are improved, and the heat exchange medium after heat exchange refluxes along the inner pipe 3 for heating. The second insulation layer 6 of the inner pipe 3 is provided with a support member 11 and a thermal insulation material 12, which is beneficial to reducing the heat loss of the heat exchange medium when it refluxes.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat preservation and heat exchange structure for medium-deep geothermal wells, characterized in that: The invention comprises a plurality of geothermal pipes arranged in a geothermal well (1), wherein the geothermal pipes comprise nested inner pipes (3) and outer pipes (2), an annulus (4) for the flow of heat exchange medium is formed between the outer pipes (2) and the inner pipes (3), the inner pipes (3) are thermal insulation pipes, the geothermal well (1) extends downward from the wellhead and comprises a first section (7) located in a temperature-variable layer, and a second section (8) located in a constant temperature layer and a temperature-increasing layer, the outer pipes (2) located in the first section (7) are provided with a first thermal insulation layer (5), the geothermal pipes located in the second section (8) are provided with a support plate (10), the support plate (10) is arranged between the inner pipes (3) and the outer pipes (2), the support plate (10) extends along the axial direction of the geothermal pipes, and the support plates (10) are evenly arranged around the inner pipes (3) in the circumferential direction.

2. The heat preservation and heat exchange structure for medium-deep geothermal wells according to claim 1, characterized in that: The support plate (10) is made of heat-conducting material.

3. The heat preservation and heat exchange structure for medium-deep geothermal wells according to claim 1 or 2, characterized in that: The number of support plates (10) in each group of geothermal pipes increases as the depth of the geothermal well (1) increases.

4. The heat preservation and heat exchange structure for medium-deep geothermal wells according to claim 3, characterized in that: The inner tube (3) has a second thermal insulation layer (6), the second thermal insulation layer (6) comprising a hollow chamber, and a support member (11) and a thermal insulation material (12) arranged in the hollow chamber, the support member (11) being an annular partition plate, the annular partition plate being evenly arranged along the length direction of the inner tube (3), and the thermal insulation material (12) being aerogel.

5. The heat preservation and heat exchange structure for medium-deep geothermal wells according to claim 3, characterized in that: The support plate (10) is made of aluminum alloy.

6. The heat preservation and heat exchange structure for medium-deep geothermal wells according to claim 1, characterized in that: The first thermal insulation layer (5) is made of hard polyurethane foam.

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