Heat insulation pipeline for terrestrial heat and preparation method thereof

Abstract

The invention discloses a heat insulation pipeline for terrestrial heat and a preparation method thereof, and the heat insulation pipeline for terrestrial heat comprises a pipeline and a heat insulation layer arranged on the outer side surface of the pipeline; the pipeline is used for collecting and transmitting terrestrial heat, and the heat insulation layer is used for conducting heat insulation on the pipeline. The heat insulation layer is formed by curing epoxy resin. According to the heat insulation pipeline for geothermal energy, heat insulation can be effectively conducted on geothermal energy transmitted in the pipeline, heat dissipated by a heat medium in the transmission process is reduced, and the utilization rate of geothermal resources is increased.

Description

Technical Field

[0001] The invention relates to geothermal resource development and utilization technology, and in particular to a geothermal heat insulation pipe and a preparation method thereof. Background Art

[0002] With the development of social economy, the demand for energy is constantly increasing. The earth contains a large amount of geothermal energy, and its reserves are about 170 million times the earth's coal resources. According to research, the heat transferred from the earth's interior to the surface and then dissipated into the universe every year is 47TW, which is equivalent to 1,000 times the total energy consumed by humans today. As a green, low-carbon, recyclable renewable energy, geothermal resources have the advantages of large reserves, stable and reliable, wide distribution, clean and environmentally friendly. Relevant experts pointed out that if geothermal energy is given corresponding attention and support, in the next few years, geothermal energy is likely to become a new energy source comparable to solar energy and wind energy.

[0003] The existing pipelines for collecting geothermal energy are mainly steel pipes, which have strong mechanical properties and can maintain good pressure resistance even at high temperatures. However, the poor thermal insulation of steel pipes causes the heat exchange medium to dissipate a lot of heat during the transmission process in the pipeline, which seriously limits the utilization rate of geothermal resources.

[0004] In order to reduce the heat dissipated by the heat medium during the transmission process and improve the utilization rate of geothermal resources, it is particularly important to design a geothermal insulation pipe and a preparation method thereof.

[0005] The information in the background technology is only for illustrating the general background of the present invention and should not be regarded as admitting or suggesting in any form that such information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0006] In order to solve at least some of the technical problems in the prior art, the present invention provides a geothermal insulated pipe and a preparation method thereof. Specifically, the present invention includes the following contents.

[0007] According to a first aspect of the present invention, there is provided an insulated geothermal pipe, comprising a pipe and an insulation layer arranged on the outer side of the pipe; the pipe is used to collect and transmit geothermal heat, and the insulation layer is used to insulate the pipe; the insulation layer material is formed by curing epoxy resin.

[0008] In certain embodiments, wherein the thermal insulation layer material further comprises glass microspheres, the curing agent used to cure the epoxy resin is m-xylylenediamine.

[0009] In certain embodiments, in the thermal insulation material, the mass fraction of epoxy resin is 56.9% to 68.6%, the mass fraction of m-xylylenediamine is 9.4% to 11.2%, and the mass fraction of glass microspheres is 20.2% to 33.7%.

[0010] In certain embodiments, the thermal insulation layer material comprises 30.51 g of epoxy resin, 4.98 g of m-xylylenediamine, and 15.01 g of glass microspheres.

[0011] In certain embodiments, in the thermal insulation layer material, the mass ratio of epoxy resin to curing agent is 6:1 to 6.33:1.

[0012] In certain embodiments, the pipe is a steel pipe.

[0013] In certain embodiments, the tube is a U-shaped tube.

[0014] A second aspect of the present invention provides an insulated geothermal pipe, which is made of an insulating layer material, and the insulating material is cured by epoxy resin, wherein the mass fraction of the epoxy resin is 56.9% to 68.6%, the mass fraction of meta-xylylenediamine is 9.4% to 11.2%, and the mass fraction of glass beads is 20.2% to 33.7%.

[0015] In certain embodiments, in the thermal insulation layer material, the mass fraction of epoxy resin is 60.4%, the mass fraction of m-xylylenediamine is 9.9%, and the mass fraction of glass microspheres is 29.7%.

[0016] The third aspect of the present invention provides a method for preparing a geothermal insulated pipe, comprising: placing glass beads in an open container, placing the container in a blast oven for drying, and then sealing the container and placing the container at room temperature for cooling; placing the epoxy resin in a hot vacuum drying oven for vacuum degassing; taking out the degassed epoxy resin from the hot vacuum drying oven and placing the container at room temperature for cooling; adding a curing agent dropwise to the cooled epoxy resin to form a mixed system of the epoxy resin and the curing agent; stirring the mixed system of the epoxy resin and the curing agent to uniformly mix the epoxy resin and the m-xylylenediamine; reducing the stirring speed, and stirring the epoxy resin and the m-xylylenediamine until the epoxy resin and the m-xylylenediamine are uniformly mixed. Slowly add dried and cooled glass microspheres into a mixed system; wherein the mass fraction of epoxy resin is 56.9% to 68.6%, the mass fraction of m-xylylenediamine is 9.4% to 11.2%, and the mass fraction of glass microspheres is 20.2% to 33.7%; pour the evenly mixed glass microspheres, epoxy resin and m-xylylenediamine into a mold, place it in a vacuum drying oven at room temperature, perform vacuum degassing, and take out the mold; cure the molded and vacuum degassed mixed system at room temperature to obtain a thermal insulation layer material; and make the thermal insulation layer material into a geothermal thermal insulation pipe or form a thermal insulation layer attached to the outside of the thermal insulation pipe.

[0017] The geothermal insulated pipe of the present invention can effectively insulate the geothermal energy transmitted in the pipe by providing the thermal insulation material prepared by curing epoxy resin, reduce the heat dissipated by the heat medium during the transmission process, and improve the utilization rate of geothermal resources.

[0018] It should be understood that the above general description and the following detailed description are merely exemplary and illustrative and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings are a part of the specification of the present invention, and illustrate exemplary embodiments of the present invention. Together with the description of the specification, the accompanying drawings are used to explain the principles of the invention.

[0020] Figure 1 It is a schematic diagram of an existing geothermal power station;

[0021] Figure 2 It is a schematic diagram of the existing multi-well interconnection mode;

[0022] Figure 3 It is a schematic diagram of the existing U-shaped mode;

[0023] Figure 4 It is a schematic diagram of the existing U-tube mode;

[0024] Figure 5 It is a schematic diagram of the existing casing mode;

[0025] Figure 6is a schematic diagram of a process for preparing the thermal insulation layer material according to an embodiment of the present invention;

[0026] Figure 7 It is a schematic diagram of the compression test results of the geothermal insulation layer material according to one embodiment of the present invention. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that the upper and lower limits of the scope and each intermediate value therebetween are specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail. Unless otherwise specified, "%" is a percentage based on weight.

[0030] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise specified, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0031] In addition, the terms "include", "comprise", "have" or any other variations thereof are intended to cover non-exclusive inclusion, so that a structure or component including a series of elements includes not only those elements, but also other mechanical elements that are not explicitly listed or inherent in the structure or component. In the absence of more restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the article or device including the elements.

[0032] Spatially related terms such as "below", "beneath", "under", "low", "above", "on", "high", etc. are used to facilitate description to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device in addition to orientations different from those shown in the figures. In addition, for example, "one element is above / below another element" can mean that the two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first", "second", etc. are also used to describe various elements, regions, parts, etc., and do not specifically refer to the meaning of order or sequence, and should not be regarded as limiting. Similar terms are used throughout the description to represent similar elements.

[0033] Example

[0034] The invention includes a geothermal heat insulation pipeline, which includes a pipeline and a heat insulation layer arranged on the outer side of the pipeline. The pipeline is used to collect and transmit geothermal heat, and the heat insulation layer is used to insulate the pipeline. The heat insulation layer material is formed by curing epoxy resin.

[0035] Specifically, geothermal energy, as a renewable clean energy with huge reserves, is a realistic and competitive new energy source, and is also a national strategic energy source. According to surveys, the geothermal energy stored within 2,000 meters from the surface is equivalent to 250 billion tons of standard coal. According to the burial depth, geothermal resources can be divided into three categories: shallow geothermal energy within 200 meters; middle geothermal energy between 200 meters and 3,000 meters; and deep geothermal energy between 3,000 meters and 10,000 meters. At present, most of the geothermal energy used in the world is shallow geothermal energy, which is mined using ground source heat pump (GSHP) technology for heating and cooling buildings. The temperature range of middle-layer geothermal energy is 20℃~150℃, and it is mainly mined using CGH closed deep geothermal heat pump technology. The temperature range of deep geothermal energy is 40℃~350℃, and it is mainly mined using geothermal water direct utilization technology and CGH closed deep geothermal heat pump technology. Among them, the middle and deep layers of geothermal energy have great potential for application and high utilization value, and are the main focus of my country's future research and utilization of geothermal energy. Figure 1 shown.

[0036] According to the survey, the geothermal energy collection companies represented by Shuangliang Energy Saving, Hanzhong Precision Machinery, and Lute Energy mainly use steel pipes for geothermal energy collection. However, the thermal insulation capacity of steel pipes is poor. In addition, long-term work in an environment rich in high-temperature water vapor will cause steel pipes to rust and become scrapped. The replacement of scrapped steel pipes will undoubtedly further increase the cost of geothermal resource extraction. In addition, due to the high density of steel pipes themselves, when the laid steel pipes are long, the dead weight of the steel pipes will cause the pipe joints to break, seriously threatening the safety of geothermal wells.

[0037] At present, the main methods of exploiting medium-deep geothermal resources are multi-well exploitation and single-well exploitation. The multi-well exploitation methods mainly include multi-well interconnected type and U-type (such as Figure 2 and 3 As shown). The multi-well interconnected type is that multiple geothermal wells implement the input of heat exchange medium, and the heat exchange medium after heat collection (heat exchange) is uniformly transported back to the ground by the same insulation well. For the U-type, the geothermal well and the insulation well collect geothermal heat through the circulating medium in the U-shaped tube, such as the patent with publication number CN210463629U.

[0038] There are two main single well production modes: U-tube and casing (such as Figure 4 and 5 The single-well U-tube type is to add a casing outside the U-tube, and use the circulating pump in the well to disturb the geothermal water in the aquifer, so that it flows through the casing and exchanges heat with the U-tube medium, and then returns to the aquifer from the outside of the casing. The casing-type transmission pipe transports geothermal resources to the ground through the inner channel. After the geothermal water releases its energy on the ground, it is recharged by the outer pipe, and the cycle repeats.

[0039] Compared with multi-well mining, single-well mining omits the laying of underground lateral pipelines. The underground pipelines work under high temperature conditions for a long time, have a short lifespan, and are difficult to lay and replace. Therefore, single-well mining has lower technical requirements for laying pipelines. However, due to the lack of efficient heat collection of lateral pipelines, the single-well has limited ability to collect geothermal resources. In addition, single-well collection and reinjection occur in the same pipeline, which puts higher requirements on the thermal insulation performance of the intermediate layer insulation material. At present, from the perspective of the published patents, the efficiency of single-well geothermal pipes is mainly improved from two aspects. For example, the patents with publication numbers CN107525292A and CN209263397U can improve the heat collection capacity of a single well to a certain extent by adding protrusions or ribs on both sides of the outer casing. The patent with publication number CN210716336U increases the thermal insulation performance of the pipeline by enhancing the thermal insulation capacity of the inner pipe, which can effectively improve the utilization rate of geothermal energy.

[0040] Thermal conductivity is a key indicator of whether a pipeline can effectively utilize thermal energy. Materials with low thermal conductivity can better preserve thermal energy and reduce thermal energy loss during geothermal collection and transportation.

[0041] Specifically, the thermal conductivity of steel pipes used in existing geothermal resource exploitation is about 50 to 60 W / (m·K), and the thermal conductivity of steel with a higher carbon content is lower, generally between 45 and 50 W / (m·K). Due to the high thermal conductivity of steel pipes, if steel pipes are directly used in geothermal energy exploitation, it will cause a huge waste of geothermal energy. In addition, some common thermal insulation materials, such as PPR and PE. The researchers and developers of this application have found through research that after the thermal insulation material is sprayed, film-formed, and solidified to form an insulation layer by special equipment, the thermal insulation performance of the steel pipe can be covered to a certain extent. The relevant data of the above two thermal insulation materials are shown in Table 1:

[0042] Table 1 Related data of PPE and PE

[0043]

[0044] However, the thermal conductivity of PPR and PE is still difficult to meet the actual needs of geothermal resource exploitation and utilization. In addition, the safe use temperature of existing thermal insulation materials such as PPR and PE is below 100°C. The storage environment of medium-deep geothermal resources is as high as 150°C, and existing thermal insulation materials are difficult to be used in geothermal resource exploitation for a long time.

[0045] The geothermal insulated pipe of this embodiment can effectively insulate the geothermal energy transmitted in the pipe by setting the thermal insulation material prepared by curing epoxy resin with a curing agent, reduce the heat dissipated by the heat medium during the transmission process, and improve the utilization rate of geothermal resources.

[0046] According to one embodiment of the present invention, the heat insulation layer material further includes glass microspheres, and the curing agent used to cure the epoxy resin is m-xylylenediamine.

[0047] The heat insulation layer of the geothermal heat insulation pipe of this embodiment can effectively improve the heat insulation capacity of the epoxy-based material by adding hollow glass microspheres (HGM).

[0048] According to one embodiment of the present invention, in the insulation layer material, by setting the ratio of epoxy resin and curing agent, for example, the ratio of epoxy resin and curing agent can be 6:1, the curing effect of the matrix can be significantly improved, the curing time is shortened, and the cured epoxy resin has good mechanical properties.

[0049] Thermal conductivity test

[0050] Table 2 is a test comparison table of adding different amounts of epoxy resin, xylenediamine and hollow glass microspheres for testing, which can clearly show the change of thermal conductivity with the distribution ratio of each group:

[0051] Table 2 Relevant data of thermal insulation materials with different raw material configurations

[0052]

[0053]

[0054] According to one embodiment of the present invention, as shown in the test of the proportion of each group in Table 2, in the thermal insulation layer material, the mass fraction of glass microspheres is added in an amount of 0% to 33.7%, the epoxy resin accounts for 56.9% to 85.7%, and the curing agent m-xylenediamine accounts for 9.4% to 14.3%. The test was conducted to measure the thermal conductivity of the final product. It was verified by the test that when the proportion of the three is 56.9% to 74.2% of epoxy resin, 9.4% to 11.7% of m-xylenediamine, and 14.1% to 33.7% of hollow glass microspheres, the thermal conductivity coefficient is less than 0.2, which is much better than materials such as PPR and PE.

[0055] Furthermore, when the proportion of the three is between 56.9% and 68.6% for epoxy resin, 9.4% and 11.2% for curing agent m-phenylenediamine, and 20.2% and 33.7% for hollow glass microspheres, the thermal conductivity is less than 0.185 and is between 0.1797 and 0.184.

[0056] According to one embodiment of the present invention, as shown in the fifth group ratio in Table 2, the lowest thermal conductivity is obtained when the insulation layer material contains 30.51g epoxy resin, 4.98g m-phenylenediamine and 15.01g glass beads, that is, the mass percentages of the three are 60.4%, 9.9% and 29.7% respectively.

[0057] In this embodiment, the thermal conductivity of the thermal insulation layer material is measured experimentally, and it is known that the epoxy resin thermal insulation material prepared with this ratio can reduce its thermal conductivity to 0.1797W / m*K, thereby effectively improving the thermal insulation effect of the thermal insulation layer.

[0058] It can be seen from Table 2 that the thermal conductivity of the thermal insulation material prepared by this embodiment is significantly lower than that of the commonly used thermal insulation material, and can better meet the requirements of geothermal resource exploitation and utilization. By configuring the thermal insulation layer prepared by this embodiment in the pipeline, it can meet the requirements of a long-term working environment of 135°C or even 150°C, and its heat resistance is far better than that of ordinary thermal insulation materials. By greatly reducing the heat conduction system, the utilization efficiency of geothermal resources is greatly expanded, and it has a very broad application prospect in the field of geothermal resource utilization.

[0059] Withstand voltage test

[0060] Similarly, the five groups of test data in Table 2 were prepared by spraying the insulation layer material onto the outer side of the pipeline, and the pipeline was subjected to a compression test. The geothermal insulation pipeline was subjected to pressure measurement, and the experimental data and experimental results are shown in Tables 3 and Figure 7 As shown:

[0061] Table 3. Data related to the compression test of the geothermal insulation pipe

[0062] Serial number Sample thickness (mm) Sample width (mm) <![CDATA[Tensile strength limit σ b (MPa)]]> 1 4 10 485 2 4 9 397.2 3 5 9 320 4 4 10 397.5 5 4 9 230.5

[0063] The compression test results show that when glass beads are added, when the mass content of the glass beads is 29.7%, the compressive resistance of the geothermal insulation pipe is the best.

[0064] In addition, there are two main ways to prevent corrosion of heat transfer pipes: one is outer layer corrosion, and the most widely used technology is the combination of polyurethane insulation layer and PE jacket layer; the other is inner layer corrosion, and the two methods of ion exchange softening water technology and adding alkaline chemical raw materials (such as soda ash, flake caustic soda, etc.) to the pipe network system are mainly used to reduce inner layer corrosion. However, this cannot prevent pipeline corrosion or even perforation accidents. It has been verified by experiments that the geothermal insulated pipe prepared by this embodiment also has strong anti-corrosion performance. It has been verified by experiments that the geothermal insulated pipe prepared by this embodiment also has strong corrosion resistance.

[0065] According to one embodiment of the present invention, the pipeline may be a steel pipe.

[0066] According to one embodiment of the present invention, the pipeline may be a U-shaped pipe.

[0067] According to one embodiment of the present invention, the pipeline is a sleeve, and the heat insulation layer is arranged on the outer side of the inner pipe.

[0068] On the other hand, the present invention provides a geothermal insulated pipe, which is made of the above-mentioned insulation layer material.

[0069] The density test shows that the density of the geothermal insulation pipe in this application is 0.6g / cm 3 ~1.2g / cm 3 Adjustable range.

[0070] According to one embodiment of the present invention, the geothermal insulated pipe is made of an insulation layer material, and the insulation material is cured by epoxy resin, wherein the mass fraction of the epoxy resin is 56.9% to 68.6%, the mass fraction of m-phenylenediamine is 9.4% to 11.2%, and the mass fraction of glass beads is 20.2% to 33.7%.

[0071] According to one embodiment of the present invention, in the heat insulation layer material, the mass fraction of epoxy resin is 60.4%, the mass fraction of m-xylylenediamine is 9.9%, and the mass fraction of glass microspheres is 29.7%.

[0072] It has been verified through experiments that the density of the geothermal insulated pipe made of the above-mentioned insulation layer material is less than 1, that is, the density of the geothermal insulated pipe is less than the density of water.

[0073] On the other hand, the present invention provides a method for preparing a geothermal insulated pipe (the above-mentioned insulation layer material can be prepared by this method), comprising:

[0074] The glass beads are placed in an open container, placed in a forced air oven for drying, and then sealed and placed at room temperature for cooling;

[0075] The epoxy resin is placed in a hot vacuum drying oven for vacuum degassing;

[0076] Take out the degassed epoxy resin from the hot vacuum drying oven and place it at room temperature to cool;

[0077] Adding the curing agent dropwise into the cooled epoxy resin to form a mixed system of the epoxy resin and the curing agent;

[0078] Stirring the mixed system of epoxy resin and curing agent to uniformly mix the epoxy resin and m-xylylenediamine;

[0079] The stirring speed is reduced, and the dried and cooled glass microspheres are slowly added to the mixed system of the epoxy resin and the meta-xylylenediamine, wherein the mass fraction of the epoxy resin is 56.9% to 68.6%, the mass fraction of the meta-xylylenediamine is 9.4% to 11.2%, and the mass fraction of the glass microspheres is 20.2% to 33.7%;

[0080] Pour the evenly mixed glass beads, epoxy resin and m-xylylenediamine into a mold, place it in a vacuum drying oven at room temperature for vacuum degassing, and take out the mold;

[0081] The mixed system that has been molded and vacuum degassed is cured at room temperature to obtain a heat insulation layer material;

[0082] The heat insulation material is made into a heat-insulating pipe for geothermal use or forms a heat-insulating layer attached to the outside of the heat-insulating pipe.

[0083] like Figure 6 As shown, according to one embodiment of the present invention, the method for preparing the thermal insulation layer specifically includes:

[0084] S01: Place glass microspheres (such as hollow glass microspheres) in an open container, place in a forced air oven at 80° C. for drying for 2 hours, and then seal and place at room temperature for cooling;

[0085] S02: Weigh a certain amount of epoxy resin (such as AG-80), and place the epoxy resin in a hot vacuum drying oven at 80°C for 30 minutes for vacuum degassing;

[0086] S03: taking out the degassed epoxy resin from the hot vacuum drying oven and placing it at room temperature to cool;

[0087] S04: weighing a certain amount of meta-xylylenediamine (HTDA), and adding a curing agent dropwise into the cooled epoxy resin to form a mixed system of the epoxy resin and the curing agent;

[0088] S05: stirring the mixed system of epoxy resin and curing agent at a stirring speed of 50 rpm for 40 minutes to uniformly mix the epoxy resin and m-xylylenediamine;

[0089] S06: reducing the stirring speed to 10 rpm, slowly adding the dried and cooled glass microspheres into the uniformly mixed epoxy resin and m-xylylenediamine system;

[0090] S07: Pour the mixed system of glass microspheres, epoxy resin and m-xylylenediamine into a mold, place it in a vacuum drying oven at room temperature for 50 minutes for vacuum degassing, and take out the mold;

[0091] S08: The molded and vacuum-degassed mixed system is placed at room temperature for pre-curing for 24 hours, cured at 75° C. for 2 hours, and cured at 100° C. for 2 hours to obtain a thermal insulation material.

[0092] As mentioned above, six sets of data of the thermal insulation material, that is, six embodiments in the preparation process of the thermal insulation material of the present application, are as follows:

[0093] In Example 1, 30 g of epoxy resin and 5 g of m-xylylenediamine were weighed respectively, and the above steps were used to prepare a heat insulation layer material.

[0094] In Example 2, 30.46 g of epoxy resin, 4.97 g of m-xylylenediamine and 3.05 g of glass beads were weighed respectively, and the thermal insulation layer material was prepared using the above steps.

[0095] Example 3: 31.67 g of epoxy resin, 5 g of m-xylylenediamine and 6 g of glass beads were weighed respectively, and the above steps were used to prepare a heat insulation layer material.

[0096] In Example 4, 30.43 g of epoxy resin, 4.97 g of m-xylylenediamine and 8.98 g of glass beads were weighed respectively, and the above steps were used to prepare a heat insulation layer material.

[0097] In Example 5, 30.51 g of epoxy resin, 4.98 g of m-xylylenediamine and 15.01 g of glass beads were weighed respectively, and the above steps were used to prepare a heat insulation layer material.

[0098] In Example 6, 30.42 g of epoxy resin, 5 g of m-xylylenediamine and 18 g of glass beads were weighed respectively, and the above steps were used to prepare a heat insulation layer material.

[0099] For details about the thermal conductivity, density, pressure resistance, etc. of different ratios, please see the previous analysis and summary. In short, as the mass content of glass beads increases, the thermal conductivity of the insulation layer material gradually decreases, and as the mass content of epoxy resin decreases, the thermal conductivity tends to decrease. But from the perspective of thermal conductivity alone, how to achieve the best ratio between the two, the R&D personnel of this application have conducted a large number of experiments. After testing, when the epoxy resin is 60.4% and the mass content of glass beads is 29.7%, the thermal conductivity of the insulation layer material reaches the lowest, which is only 0.1797. Compared with ordinary steel pipes, the geothermal insulated pipes prepared by the above-mentioned method for preparing geothermal insulated pipes can reduce the thermal conductivity by about 99%, which greatly improves the thermal insulation performance of the geothermal insulated pipes and improves the efficiency of geothermal collection.

[0100] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. Various adjustments or changes may be made to the exemplary embodiments of the present specification without departing from the scope or spirit of the present invention. The scope of the claims should be based on the broadest interpretation to cover all modifications and equivalent structures and functions.

Claims

1. A geothermal insulated pipe, characterized in that: It comprises a pipeline and a heat-insulating layer arranged on the outer side of the pipeline; the pipeline is used to collect and transmit geothermal heat, and the heat-insulating layer is used to insulate the pipeline; the heat-insulating layer material is formed by curing epoxy resin.

2. The geothermal insulated pipe according to claim 1, characterized in that: The heat insulation layer material also includes glass microspheres, and the curing agent used to cure the epoxy resin is m-xylylenediamine.

3. The geothermal insulated pipe according to claim 2, characterized in that: In the thermal insulation material, the mass fraction of epoxy resin is 56.9% to 68.6%, the mass fraction of meta-xylylenediamine is 9.4% to 11.2%, and the mass fraction of glass microspheres is 20.2% to 33.7%.

4. The geothermal insulated pipe according to claim 3, characterized in that: The heat insulation layer material comprises 30.51 g of epoxy resin, 4.98 g of m-xylylenediamine and 15.01 g of glass microspheres.

5. The geothermal insulated pipe according to claim 1, characterized in that: In the thermal insulation layer material, the mass ratio of epoxy resin to curing agent is 6:1 to 6.33:

1.

6. The geothermal insulated pipe according to claim 1, characterized in that: The pipeline is a steel pipe.

7. The geothermal insulated pipe according to claim 1, characterized in that: The pipeline is a U-shaped pipe.

8. A geothermal insulated pipe, characterized in that: The thermal insulation layer is made of a heat-insulating layer material, and the heat-insulating material is cured by epoxy resin, wherein the mass fraction of the epoxy resin is 56.9% to 68.6%, the mass fraction of m-xylylenediamine is 9.4% to 11.2%, and the mass fraction of glass microspheres is 20.2% to 33.7%.

9. The geothermal insulated pipe according to claim 8, characterized in that: In the heat insulation layer material, the mass fraction of epoxy resin is 60.4%, the mass fraction of m-xylylenediamine is 9.9%, and the mass fraction of glass microspheres is 29.7%.

10. A method for preparing a geothermal insulated pipe, characterized in that: include: The glass beads are placed in an open container, placed in a forced air oven for drying, and then sealed and placed at room temperature for cooling; The epoxy resin is placed in a hot vacuum drying oven for vacuum degassing; Take out the degassed epoxy resin from the hot vacuum drying oven and place it at room temperature to cool; Adding the curing agent dropwise into the cooled epoxy resin to form a mixed system of the epoxy resin and the curing agent; Stirring the mixed system of epoxy resin and curing agent to uniformly mix the epoxy resin and m-xylylenediamine; The stirring speed is reduced, and the dried and cooled glass microspheres are slowly added to the mixed system of the epoxy resin and the meta-xylylenediamine, wherein the mass fraction of the epoxy resin is 56.9% to 68.6%, the mass fraction of the meta-xylylenediamine is 9.4% to 11.2%, and the mass fraction of the glass microspheres is 20.2% to 33.7%; Pour the evenly mixed glass beads, epoxy resin and m-xylylenediamine into a mold, place it in a vacuum drying oven at room temperature for vacuum degassing, and take out the mold; The mixed system that has been molded and vacuum degassed is cured at room temperature to obtain a heat insulation layer material; The heat insulation layer material is made into a heat insulation pipe for geothermal use or forms a heat insulation layer attached to the outside of the heat insulation pipe.

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