A method for hot rotational molding of underground hydrogen storage wells and underground hydrogen storage wells

Abstract

This invention relates to the field of underground hydrogen storage well processing technology, specifically to a hot rotational molding method for underground hydrogen storage wells and an underground hydrogen storage well. The molding method includes: firstly, assembling single-section hydrogen storage cylinders and inter-cylinder connectors into a composite component for integral hot rotational molding; then, cutting and disassembling the connection area; and finally, reorganizing the coating structure by connecting multiple coated hydrogen storage cylinders in series and combining them with hot-melt welding technology. Under the synergistic effect of the three-stage process, a uniform, continuous, and high-bonding-strength integral polymer lining is formed on the inner wall of the ultra-long underground hydrogen storage well, which can achieve a low hydrogen permeability coefficient and a high resistance to hydrogen embrittlement.

Description

Technical Field

[0001] This invention relates to the field of underground hydrogen storage well processing technology, and in particular to a hot rotational molding method for underground hydrogen storage wells and an underground hydrogen storage well. Background Technology

[0002] With the rapid increase in societal demand for clean energy storage, high-pressure gaseous hydrogen storage technology has become a core development direction due to its high efficiency and maturity. Among these technologies, underground hydrogen storage wells, as an emerging type of high-pressure hydrogen storage container, significantly reduce the risk of explosion by deeply burying steel well casings and utilizing the confinement effect of surrounding concrete. Compared to traditional surface hydrogen storage tanks, they exhibit outstanding advantages such as high safety, small footprint, and convenient maintenance, attracting widespread attention. However, due to the small size and high permeability of hydrogen molecules, they easily penetrate the steel well wall and seep into the metal matrix, reacting with carbon elements or alloy components in the steel to generate methane gas that accumulates and forms high pressure, or directly induces hydrogen-induced cracks. This leads to a severe decrease in material strength, abnormal local stress concentration, and ultimately, delayed and sudden brittle fracture failure, posing a significant threat to the long-term safe operation of hydrogen storage wells.

[0003] Currently, polymer hydrogen barrier materials are showing promising application prospects due to their excellent flexibility, corrosion resistance, and processability. When combined with steel well bodies as linings, they can construct an effective physical barrier layer, directly isolating hydrogen from the metal substrate and thus delaying hydrogen embrittlement. Underground hydrogen storage wells are typically hundreds or even thousands of meters deep, with their main structure consisting of multiple standardized hydrogen storage cylinders connected in series via inter-cylinder connectors. This modular design not only ensures high stress distribution uniformity and stability of the well body but also simplifies installation and enhances structural reliability, making it an ideal technical solution for constructing ultra-long, deep wells. However, traditional lining forming processes (such as winding and spraying) are difficult to ensure uniform coating and bonding strength when applied to the narrow inner walls of deep wells, making it difficult to form a highly integrated coating lining for the entire underground hydrogen storage well. Furthermore, under the unavoidable pressure cycling fluctuations during actual operation of hydrogen storage wells, the interface between the polymer lining and the metal substrate is prone to peeling failure or a sharp increase in the permeability of the barrier layer, making it difficult to guarantee its long-term stability and hydrogen barrier effect.

[0004] Therefore, developing a new protective technology that can meet the needs of ultra-long deep well applications, which must ensure high uniformity, high integrity of the coating and excellent interfacial stability with the substrate, in order to achieve a long-term and reliable hydrogen barrier effect, is of great significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the difficulty of forming a uniform, continuous, and high-bonding-strength integral barrier layer on the inner wall of ultra-long underground hydrogen storage wells using traditional polymer liner molding processes. This compromises the hydrogen barrier effect and severely restricts the effective application of polymer liners in underground hydrogen storage wells. The invention provides a hot rotational molding method for underground hydrogen storage wells and the resulting underground hydrogen storage well. This process can construct an axially continuous hydrogen barrier structure, forming a uniform, continuous, and high-bonding-strength integral polymer liner on the inner wall of ultra-long underground hydrogen storage wells, facilitating widespread application.

[0006] The first aspect of the present invention provides a method for hot rotational molding of underground hydrogen storage wells, comprising the following steps:

[0007] S1. Assemble single-section hydrogen storage cylinders and inter-cylinder connectors to form a composite assembly;

[0008] S2. Perform hot rotational molding on the inner wall of the composite component;

[0009] S3. Cut the hot-rolled coating at the connection between the hydrogen storage cylinder and the cylinder connector;

[0010] S4. Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder and a coated inter-cylinder connector;

[0011] S5. Repeat steps S1-S4;

[0012] S6. Connect multiple coated hydrogen storage cylinders sequentially using coated cylinder connectors to form a hydrogen storage well.

[0013] S7. Use hot melt welding technology to repair the gaps in the hot rotomolded coating of adjacent hydrogen storage cylinders and the connecting parts between cylinders, and complete the hot rotomolding of underground hydrogen storage wells.

[0014] This invention provides a method for hot rotational molding of underground hydrogen storage wells. First, single hydrogen storage cylinders and inter-cylinder connectors are assembled into a composite component and then hot-rolled. Next, the connection area is cut and disassembled. Finally, multiple coated hydrogen storage cylinders are connected in series and then combined with hot-melt welding technology to reorganize the coating structure. Under the synergistic effect of the three-stage process, an axially continuous hydrogen-blocking structure is constructed, forming a uniform, continuous, and high-bonding-strength integral polymer liner on the inner wall of the ultra-long underground hydrogen storage well. This achieves a low hydrogen permeability coefficient and a high resistance to hydrogen embrittlement.

[0015] Furthermore, the hydrogen storage cylinder is a steel structural component.

[0016] Furthermore, the inter-cylinder connector is a steel structural component.

[0017] Furthermore, S1 also includes sandblasting the inner wall of the composite component.

[0018] Furthermore, in S1, in the composite component, inter-tube connectors are respectively assembled at both ends of the single section of the hydrogen storage cylinder.

[0019] Furthermore, the S1-S5 process also includes hot rolling treatment of only a single hydrogen storage cylinder.

[0020] Furthermore, S1 also includes applying a primer to the inner wall of the composite component, the primer material comprising maleic acid and / or an organic solvent, wherein the organic solvent is at least one of decahydronaphthalene and xylene.

[0021] Furthermore, the total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 5-10 g / m². 2 Preferably, the total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 8-10 g / m³. 2 .

[0022] Furthermore, in the primer material, the mass ratio of maleic acid to organic solvent is 0.5 to 2:1. Preferably, in the primer material, the mass ratio of maleic acid to organic solvent is 1 to 2:1.

[0023] Furthermore, in step S3, a V-shaped groove is formed by circumferentially cutting the hot-rolled coating on the axial contact surface between the inter-cylinder connector and the hydrogen storage cylinder. Even further, the angle of the V-shaped groove is 60° to 120°. Preferably, the V-shaped groove is symmetrically arranged along the axial contact surface between the inter-cylinder connector and the hydrogen storage cylinder.

[0024] Furthermore, the specific operation process of S2 is as follows:

[0025] Step 1: Place the thermoplastic material inside the composite component, and seal both ends of the composite component;

[0026] Step 2: Rotate the composite component and heat it;

[0027] Step 3: Keep the component warm and rotate until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0028] Step 4: Stop rotating, allow to cool, and remove the seal.

[0029] Furthermore, in step 2, the heating treatment includes open flame heating, hot oil immersion heating, or hot air heating.

[0030] Furthermore, in step 2, the composite component is heated to a temperature 0°C to 30°C above the melting point of the hot rotomolded material.

[0031] Furthermore, the rotational speed of the composite component is 5 r / min to 200 r / min.

[0032] Furthermore, in step 3, the heat preservation and rotation time is 20 min to 80 min.

[0033] Furthermore, in step 3, after heating is stopped, while maintaining rotation, a silicone bag is inserted into the composite component and inflated, so that the silicone bag expands to fill the cavity of the composite component and is then pressurized.

[0034] Furthermore, air at 80°C to 100°C is introduced into the silicone bag.

[0035] Furthermore, the holding pressure is 0.1MPa to 0.3MPa.

[0036] Furthermore, the pressure holding time is 5 to 10 minutes.

[0037] A second aspect of the present invention provides an underground hydrogen storage well, comprising:

[0038] A multi-section hydrogen storage cylinder, the inner wall of which is provided with a hot-rolled coating, and the multiple sections of the hydrogen storage cylinder are arranged in series;

[0039] Multiple inter-cylinder connectors, the inner wall of which is provided with a hot-rolled coating, are fitted onto the mating ends of two adjacent hydrogen storage cylinders;

[0040] The hot-rolled coating of the hydrogen storage cylinder and the hot-rolled coating of the cylinder connector form an axially continuous seamless transition zone at the connection point through hot-melt welding.

[0041] This invention provides an underground hydrogen storage well, the main structure of which is formed by connecting multiple hydrogen storage cylinders one by one in series through inter-cylinder connectors. This modular design can ensure that the well cylinder as a whole has high stress distribution uniformity and structural stability. At the same time, the hot-rolled coating of adjacent hydrogen storage cylinders achieves axial continuous transition through the hot-rolled coating of the inter-cylinder connectors, forming a continuous, uniform and highly bonded hot-rolled coating on the inner wall of the underground hydrogen storage well, which can achieve a low hydrogen permeability coefficient and achieve a high resistance to hydrogen embrittlement.

[0042] Its main structure consists of multiple standardized hydrogen storage cylinders connected in series with inter-cylinder connectors, employing a segmented installation process. This modular design not only ensures high stress distribution uniformity and excellent fatigue resistance of the wellbore as a whole, but also makes it an ideal technical solution for constructing ultra-long deep wells due to its simplified installation process and high structural reliability.

[0043] Furthermore, the inter-cylinder connector is a hollow cylindrical structure, and an annular boss is provided on the inner side of the inter-cylinder connector, the annular boss being arranged along the circumference of the inter-cylinder connector;

[0044] The hydrogen storage cylinder has external threads at both ends, and the cylinder connector has matching internal threads inside.

[0045] When the external thread and the internal thread are screwed to their limit positions, the hydrogen storage cylinder and the cylinder connector form an abutment at their axial contact points.

[0046] Furthermore, the gap at the connection between the hydrogen storage cylinder and the inter-cylinder connector is heat-fused with a hot-rolled plastic material to form a seamless transition zone. Preferably, the gap at the connection between the hydrogen storage cylinder and the inter-cylinder connector is formed by in-situ heat-fusion welding using a wall-climbing robot to create a seamless transition zone.

[0047] Furthermore, the hydrogen permeability coefficient of the underground hydrogen storage well is ≤50×10⁻⁶. -15 mol·m / (m 2 • Pa), and / or, peel strength ≥ 65 N / cm, and / or, thickness error of the hot-rolled coating on the inner wall surface ≤ 15 micrometers. The beneficial effects of this invention compared to the prior art are:

[0048] 1. This invention provides a method for hot rotational molding of underground hydrogen storage wells. First, single hydrogen storage cylinders and inter-cylinder connectors are assembled into a composite component and then hot-rolled. Then, the connection area is cut and disassembled. Finally, multiple coated hydrogen storage cylinders are connected in series and combined with hot-melt welding technology to achieve coating structure reorganization. Under the synergistic effect of the three-stage process, a uniform, continuous, and high-bonding-strength integral polymer lining is formed on the inner wall of an ultra-long underground hydrogen storage well, achieving significant progress.

[0049] 2. This invention provides an underground hydrogen storage well. The main structure is formed by connecting multiple hydrogen storage cylinders sequentially through inter-cylinder connectors. This modular design ensures high stress distribution uniformity and structural stability of the well casing. Simultaneously, the connection between the hydrogen storage cylinders and the inter-cylinder connectors features a seamless transition zone formed by hot-melt welding. The hot-rolled coatings of adjacent hydrogen storage cylinders achieve a continuous axial transition through the hot-rolled coatings of the inter-cylinder connectors, forming a continuous, uniform, and highly adhesive hot-rolled coating on the inner wall of the underground hydrogen storage well. This results in a low hydrogen permeability coefficient and high resistance to hydrogen embrittlement, with a hydrogen permeability coefficient less than or equal to 50 × 10⁻⁶. -15 mol. m / (m 2 The peel strength can reach greater than or equal to 65 N / cm, and the thickness error of the hot roll coating on the inner wall surface is ≤15 micrometers. Attached Figure Description

[0050] Figure 1 This is a cross-sectional view of one end of the composite component of this application.

[0051] Figure 2 This is a cross-sectional structural diagram of the underground hydrogen storage well of this application.

[0052] Figure 3 for Figure 2 A magnified structural diagram of A in the diagram.

[0053] Figure 4 A schematic diagram of the V-shaped groove at the interface connecting the hydrogen storage cylinder and the cylinder connector.

[0054] Figure 5 for Figure 4 A schematic diagram of the structure after hot-melt repair.

[0055] The markings in the diagram are: 1-hydrogen storage cylinder; 2-inter-cylinder connector; 3-connection between hydrogen storage cylinder and inter-cylinder connector in the composite component; 4-plug; 5-concrete pouring layer; 6-hot-rolled plastic coating of hydrogen storage cylinder; 7-hot-rolled plastic coating of inter-cylinder connector; 8-hot-melt repair at the interface between hydrogen storage cylinder and inter-cylinder connector. Detailed Implementation

[0056] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0057] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0058] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0059] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0060] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0061] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0062] The first aspect of this embodiment provides a method for hot rotational molding of underground hydrogen storage wells, including the following steps:

[0063] S1. Assemble a single hydrogen storage cylinder 1 and the cylinder connector 2 to form a composite assembly;

[0064] S2. Perform hot rotational molding on the inner wall of the composite component;

[0065] S3. Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component.

[0066] S4. Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2.

[0067] S5. Repeat steps S1-S4;

[0068] S6. Connect the multi-section coated hydrogen storage cylinder 1 sequentially using coated cylinder connector 2 to form a hydrogen storage well.

[0069] S7. Use hot melt welding technology to repair the gaps in the hot rotomolded coating between adjacent hydrogen storage cylinder 1 and cylinder connector 2, and complete the hot rotomolding of the underground hydrogen storage well.

[0070] This embodiment provides a method for hot rotational molding of underground hydrogen storage wells. First, a single section of hydrogen storage cylinder 1 and the connecting parts 2 are assembled into a composite component and hot-rolled as a whole. Then, the connecting area is cut and disassembled. Finally, the coating structure is reorganized by connecting multiple coated hydrogen storage cylinders 1 in series and then using hot-melt welding technology. Under the synergistic effect of the three-stage process, a uniform, continuous, and high-bonding-strength integral polymer lining is formed on the inner wall of the ultra-long underground hydrogen storage well.

[0071] In some embodiments, the hydrogen storage cylinder 1 is a steel structural component.

[0072] In some embodiments, the inter-cylinder connector 2 is a steel structural component.

[0073] In some embodiments, the thermoplastic material is a polymer, and the polymer physical form is a mixture of powder, slices, granules, antioxidants, and lubricants.

[0074] Specifically, the polymer may be selected from at least one of high-density polyethylene (HDPE), polypropylene (PP), and polyamide (nylon 6, PA6).

[0075] Antioxidants, also known as antioxidants, can be selected from BHA (butylated hydroxyanisole), phenols, or quinones.

[0076] The lubricant is selected from at least one of calcium stearate, zinc stearate, magnesium stearate, fatty acid esters, paraffin wax, and microcrystalline wax. Preferably, calcium stearate is used as the lubricant.

[0077] It comprises 90%–96% polymer, 1%–2% antioxidant, and the balance being lubricant by weight percentage.

[0078] In some embodiments, S1 further includes sandblasting the inner wall of the composite component. Sandblasting the inner wall surface of the composite component by spraying abrasive particles helps to improve the adhesion of the hot-rolled coating.

[0079] In some embodiments, in step S1, in the composite assembly, inter-cylinder connectors 2 are respectively assembled at both ends of a single section of the hydrogen storage cylinder 1. Assembling inter-cylinder connectors 2 at both ends allows two inter-cylinder connectors 2 to be formed from a single composite assembly, making the overall operation more convenient and efficient.

[0080] In some embodiments, processes S1-S5 also include hot roll forming of only a single hydrogen storage cylinder. To accommodate the number of hydrogen storage wells and inter-cylinder connectors 2, this method of forming only the hydrogen storage cylinder is highly efficient and relatively simple.

[0081] In some embodiments, S1 further includes applying a primer to the inner wall of the composite component, the primer material comprising maleic acid and an organic solvent, wherein the organic solvent is at least one of decahydronaphthalene and xylene.

[0082] Maleic acid and / or organic solvents are coated on the inner wall of the composite component. Maleic acid, as a bonding intermediate, can form grafts with the inner wall surface of the composite component. Decahydronaphthalene and / or xylene help the local dissolution and penetration of the thermoplastic material. The two work synergistically to increase the adhesion between the hot-rolled coating and the inner wall surface of the hydrogen storage well structure. To a certain extent, during the dynamic hot-rolling process, the uniformity and continuity of the coating are improved, and the resistance to hydrogen embrittlement is enhanced.

[0083] In some embodiments, maleic acid and an organic solvent can be mixed and then the mixed solvent can be sprayed onto the inner wall of the composite component; alternatively, an aqueous solution of maleic acid can be sprayed onto the inner wall of the composite component first, and then the organic solvent can be sprayed.

[0084] In some embodiments, the total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 5 g / m³. 2 ~10g / m 2 For example, the total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 5 g / m³. 2 6g / m 2 7g / m 2 8g / m 2 9g / m 2 10g / m 2 Preferably, the total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 8-10 g / m³. 2 .

[0085] In some embodiments, the mass ratio of maleic acid to organic solvent in the primer material is 0.5 to 2:1. For example, the mass ratio of maleic acid to organic solvent in the primer material is 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2:1. Preferably, the mass ratio of maleic acid to organic solvent in the primer material is 1 to 2:1.

[0086] Studies have found that by rationally controlling the mass ratio of maleic acid to organic solvent and the total amount used per unit area, the anti-peeling performance of the hot rotomolded coating on the inner wall of the composite component can be significantly improved, and the uniformity of the hot rotomolded coating can be increased.

[0087] In some embodiments, in step S3, a V-shaped groove is formed circumferentially on the axial contact surface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1. Preferably, the V-shaped groove is symmetrically arranged along the axial contact surface between the inter-cylinder connector and the hydrogen storage cylinder. Preferably, the angle of the V-shaped groove is 60° to 120°. Setting the groove in a V-shape facilitates the pouring of molten thermoplastic material, resulting in better repair effects.

[0088] For example, the angles of the V-shaped grooves are 60°, 70°, 80°, 90°, 100°, 110°, and 120°.

[0089] Meanwhile, the study found that controlling the angle of the V-shaped groove within a reasonable range not only ensures the convenience of the hot-melt repair operation but also helps improve the connection between the material at the hot-melt repair site and the inter-cylinder connector 2 and the storage cylinder, achieving a higher resistance to hydrogen embrittlement and a lower hydrogen permeability coefficient. Preferably, the angle of the V-shaped groove is 60° to 90°.

[0090] In some embodiments, the specific operation process of S2 is as follows:

[0091] Step 1: Place the thermoplastic material inside the composite component, and seal both ends of the composite component;

[0092] Step 2: Rotate the composite component and heat it;

[0093] Step 3: Keep the component warm and rotate until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0094] Step 4: Stop rotating, allow to cool, and remove the seal.

[0095] In some embodiments, step 2, the heating treatment includes open flame heating, hot oil immersion heating, or hot air heating.

[0096] In some embodiments, in step 2, the composite component is heated to a temperature 0°C to 30°C above the melting point of the rotomolding material. For example, in step 2, the composite component is heated to a temperature 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C above the melting point of the rotomolding material. For example, in some embodiments, the composite component is heated to a temperature of 150°C to 280°C. Depending on the rotomolding material, a suitable temperature is controlled to ensure that the rotomolding material melts under reasonable temperature conditions, achieving a better rotomolding molding effect.

[0097] In some embodiments, the rotational speed of the composite component is 5 r / min to 200 r / min. Reasonably controlling the rotational speed of the composite component during hot rotational molding contributes to the uniformity and higher adhesion of the hot rotational molding coating, thus improving the coating quality. For example, the rotational speed of the composite component is 5 r / min, 6 r / min, 7 r / min, 8 r / min, 9 r / min, 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, or 200 r / min.

[0098] In some embodiments, the heat preservation and rotation time in step 3 is 20 min to 80 min. Reasonably controlling the heat preservation and rotation time can help the molten hot rotational molding material be uniformly coated and molded on the inner wall surface of the composite component. For example, in step 3, the heat preservation and rotation time is 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, or 80 min.

[0099] In some embodiments, in step 3, after heating is stopped, a silicone bag is inserted into the composite component and inflated while maintaining rotation, allowing the silicone bag to expand and fill the cavity of the composite component before maintaining pressure. This application proposes that after a hot-rolled coating is formed on the inner wall of the composite component, heating is stopped, and then a silicone bag is inserted into the composite component while maintaining rotation and inflated, allowing the silicone bag to expand and fill the cavity of the composite component before maintaining pressure. This technique can further improve the uniformity and adhesion of the hot-rolled material, and improve the coating quality of the hot-rolled coating.

[0100] In some embodiments, air at 80°C to 100°C is introduced into the silicone bag. Introducing higher-temperature air into the silicone bag first reduces the temperature impact of room-temperature air on the inner wall of the high-temperature composite component, creating a temperature buffer. This helps the silicone bag exert its physical effects on the composite component, improves the uniformity and peel resistance of the thermally rolled coating, and achieves higher resistance to hydrogen embrittlement and a lower hydrogen permeability coefficient. For example, air at 80°C, 85°C, 90°C, 95°C, and 100°C is introduced into the silicone bag.

[0101] In some embodiments, the holding pressure is 0.1 MPa to 0.3 MPa. Appropriate control of the holding pressure helps to maximize the physical effect of the silicone bag on the composite component, improving the uniformity and peel resistance of the thermally rolled coating. For example, the holding pressure is 0.1 MPa, 0.2 MPa, or 0.3 MPa. In some embodiments, the holding time is 5 min to 10 min. For example, the holding time is 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min.

[0102] In some embodiments, the method further includes continuing to circulate air into the silicone bag to allow it to cool naturally to below 50°C.

[0103] The second aspect of this embodiment provides an underground hydrogen storage well, including:

[0104] A multi-section hydrogen storage cylinder 1, the inner wall of which is provided with a hot-rolled coating, and the multiple sections of the hydrogen storage cylinder 1 are arranged in series.

[0105] Multiple inter-cylinder connectors 2, the inner wall of which is provided with a hot-rolled coating, are fitted onto the mating ends of two adjacent hydrogen storage cylinders 1; the hot-rolled coatings of the hydrogen storage cylinders 1 and the hot-rolled coatings of the inter-cylinder connectors 2 are connected by hot-melt welding to form an axially continuous seamless transition zone.

[0106] That is, a seal is formed at the axial contact point between the hydrogen storage cylinder 1 and the cylinder connector 2, and the hot-rolled coating 6 of two adjacent hydrogen storage cylinders achieves axial continuous transition through the hot-rolled coating 7 of the cylinder connector.

[0107] This embodiment provides an underground hydrogen storage well. The main structure is formed by connecting multiple hydrogen storage cylinders 1 one by one through inter-cylinder connectors 2. This modular design can ensure that the well cylinder has high stress distribution uniformity and structural stability. At the same time, the hot-rolled coating 6 of two adjacent hydrogen storage cylinders achieves axial continuous transition through the hot-rolled coating 7 of the inter-cylinder connector, forming a continuous, uniform and highly adhesive hot-rolled coating on the inner wall of the underground hydrogen storage well. This can achieve a low hydrogen permeability coefficient and a high resistance to hydrogen embrittlement.

[0108] Its main structure consists of multiple standardized hydrogen storage cylinders 1 connected in series via inter-cylinder connectors 2, using a segmented installation process. This modular design not only ensures high stress distribution uniformity and excellent fatigue resistance of the wellbore as a whole, but also makes it an ideal technical solution for constructing ultra-long deep wells due to its simplified installation process and high structural reliability.

[0109] In some embodiments, the inter-cylinder connector 2 is a hollow cylindrical structure, and an annular boss is provided on the inner side of the inter-cylinder connector 2, the annular boss being arranged along the circumference of the inter-cylinder connector;

[0110] The hydrogen storage cylinder 1 has external threads at both ends, and the inter-cylinder connector 2 has matching internal threads. When the external and internal threads are screwed into their limit positions, the hydrogen storage cylinder 1 and the inter-cylinder connector 2 form an abutment at their axial contact points. This application provides a connector with an H-shaped cross-section. Through threaded engagement, the end face of the hydrogen storage cylinder 1 and the end face of the annular protrusion are axially coplanar and sealed, which greatly facilitates operation during use. At the same time, it also helps the wellbore achieve a high degree of stress distribution uniformity and stability, simplifying the entire underground hydrogen storage well installation process and increasing structural reliability.

[0111] In some embodiments, the gap between the hydrogen storage cylinder 1 and the cylinder connector 2 is filled with molten hot rotomolding material to form a seamless transition zone.

[0112] In some embodiments, the hydrogen permeability coefficient of the underground hydrogen storage well is ≤50×10⁻⁶. -15 mol. m / (m 2 The hydrogen permeability coefficient of the underground hydrogen storage well is ≤10 × 10⁻⁶ N / cm, and / or the peel strength is ≥65 N / cm, and / or the thickness error of the hot-rolled coating on the inner wall surface is ≤15 micrometers. This allows for the formation of a uniform, continuous, and highly bonded integral polymer lining on the inner wall of an ultra-long underground hydrogen storage well. Preferably, the hydrogen permeability coefficient of the underground hydrogen storage well is ≤10 × 10⁻⁶. -15 mol·m / (m 2 • Pa), and / or, peel strength ≥ 85 N / cm, and / or, thickness error of hot roll coating on inner wall surface ≤ 5 micrometers.

[0113] To better understand the above technical solutions, the following more detailed embodiments are provided for further explanation.

[0114] In the following embodiments, the inter-cylinder connector 2 used is, for example... Figure 1 and Figure 2 The hollow cylindrical structure has an annular protrusion on the inner wall of the inter-cylinder connector 2. The annular protrusion is circumferentially arranged along the inter-cylinder connector 2. Both ends of the hydrogen storage cylinder 1 have external threads, and the inter-cylinder connector 2 has matching internal threads. When the external and internal threads are screwed to their limit positions, the axial contact points of the hydrogen storage cylinder 1 and the inter-cylinder connector 2 form an abutment, creating a seal. This H-shaped connector, through threaded engagement, ensures that the inner wall end face of the hydrogen storage cylinder 1 and the end face of the annular protrusion are axially coplanar and sealed. This provides high operational convenience and also helps the wellbore achieve high stress distribution uniformity and stability, simplifying the entire underground hydrogen storage well installation process and enhancing structural reliability.

[0115] In the following embodiments, the length of a single hydrogen storage cylinder 1 is 11m and the diameter is 300mm.

[0116] Example 1

[0117] (1) The inner walls of the single hydrogen storage cylinder 1 and the inter-cylinder connector 2 are respectively subjected to sandblasting to remove rust and roughen the surface;

[0118] The hydrogen storage cylinder 1 is assembled with inter-cylinder connectors 2 at its two opposite axial ends to form a composite assembly;

[0119] A primer is sprayed onto the inner wall of the composite component. The primer is a mixed solvent of maleic acid dissolved in decahydronaphthalene, wherein the total amount of maleic acid and decahydronaphthalene in the primer sprayed onto the inner wall of the composite component is 10 g / m³. 2 The mass ratio of maleic acid to decahydronaphthalene is 1:1.

[0120] (2) The inner wall of the composite component is subjected to overall hot rotational molding to form a coating with a thickness of 1.5 mm.

[0121] Specifically, a thermoplastic material is placed inside the composite component, and both ends of the composite component are sealed; the thermoplastic material is a mixture of 94% (by weight) HDPE polymer powder, 1% BHA antioxidant, and 5% calcium stearate lubricant. Figure 1 As shown, the hydrogen storage cylinder 1 and the cylinder connector 2 are connected by threads. The other end of the cylinder connector 2 is connected to a plug 4. The plug 4 is provided with an external thread that matches the internal thread of the cylinder connector 2.

[0122] The composite component is rotated at a speed of 100 r / min and subjected to vertical heating with an open flame at a temperature of 150°C.

[0123] Keep the temperature and rotate for 60 minutes until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0124] While maintaining rotation, insert a silicone bag into the composite component and introduce air at 100°C. After the silicone bag expands and fills the cavity of the composite component, maintain the pressure for 5 minutes at a pressure of 0.2 MPa, and then allow it to cool naturally to 50°C.

[0125] Stop rotating, cool, and remove the seal.

[0126] (3) Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component;

[0127] Specifically, a V-shaped groove is formed by circumferentially cutting the hot-rolled coating on the axial contact surface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1. The angle α of the V-shaped groove is 90°. Figure 4 As shown.

[0128] (4) Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2;

[0129] (5) Repeat steps (1)-(4) to obtain multiple coated hydrogen storage cylinders 1 and multiple coated cylinder connectors 2. During the process, when the number of cylinder connectors 2 reaches the expected number, only the hydrogen storage cylinders 1 can be subjected to hot rotation molding.

[0130] (6) Multiple coated hydrogen storage cylinders 1 are installed underground via coated cylinder connectors 2.

[0131] (7) Use hot melt welding technology to repair the gaps in the hot rotomolded coating between the adjacent hydrogen storage cylinder 1 and the cylinder connection 2, and complete the hot rotomolding of the underground hydrogen storage well.

[0132] Using the method in Example 1, a project successfully created an underground hydrogen storage well several hundred meters deep. Figure 2 and Figure 3 As shown, the device includes multiple hydrogen storage cylinders 1, each with a heat-rolled plastic coating on its inner wall, and the cylinders 1 are arranged in series. Multiple inter-cylinder connectors 2, each with a heat-rolled plastic coating on its inner wall, are fitted onto the mating ends of adjacent hydrogen storage cylinders 1. A seal is formed at the axial contact point between the hydrogen storage cylinders 1 and the inter-cylinder connectors 2. The heat-rolled plastic coatings 6 of adjacent hydrogen storage cylinders achieve a continuous axial transition through the heat-rolled plastic coatings 7 of the inter-cylinder connectors. The connection between the hydrogen storage cylinders 1 and the inter-cylinder connectors 2 has a seamless transition zone formed by heat-melt welding repair.

[0133] The exterior of the hydrogen storage well is a concrete pouring layer 5. This includes the hot-rolled plastic coating 6 of the hydrogen storage cylinder, the hot-rolled plastic coating 7 of the cylinder-to-cylinder connectors, and the hot-melt repair 8 at the interface between the hydrogen storage cylinder and the cylinder-to-cylinder connectors. Figure 3 As shown.

[0134] Test 1: The hydrogen storage well prepared in Example 1 was subjected to an overall appearance inspection using machine vision. The inspection result showed no obvious gaps or resin defects. The inner wall of the hydrogen storage well prepared by the hot rotational molding method provided in this application can form a hot rotational molding liner with good integrity and continuity.

[0135] Test: Two coated hydrogen storage cylinders 1 were installed using the coated inter-cylinder connector 2. The gaps in the hot-rolled plastic coating between adjacent hydrogen storage cylinders 1 and the inter-cylinder connector 2 were repaired using hot-melt welding technology to obtain a shorter hydrogen storage well.

[0136] The shorter hydrogen storage well obtained in Example 1 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0137] Example 2

[0138] (1) The inner walls of the single hydrogen storage cylinder 1 and the inter-cylinder connector 2 are respectively subjected to sandblasting to remove rust and roughen the surface;

[0139] One end of the single-section hydrogen storage cylinder 1 is assembled with an inter-cylinder connector 2 to form a composite component;

[0140] (2) The inner wall of the composite component is subjected to overall hot rotation molding to form a coating with a thickness of 2 mm.

[0141] Specifically, a thermoplastic material is placed inside the composite component, and both ends of the composite component are sealed; the thermoplastic material is a mixture of 94% HDPE polymer powder, 1% BHA antioxidant, and 5% calcium stearate lubricant.

[0142] The composite component is rotated at a speed of 50 r / min and subjected to vertical heating with an open flame until the temperature of the composite component is 10°C higher than the melting point of the hot rotomolded material.

[0143] Keep the temperature and rotate for 80 minutes until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0144] Stop rotating, cool, and remove the seal.

[0145] (3) Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component;

[0146] Specifically, a V-shaped groove is formed by cutting a hot-rolled coating along the circumferential direction on the axial contact surface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1. The angle of the V-shaped groove is 60°.

[0147] (4) Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2;

[0148] (5) Following the same hot roll forming process as described above, another single hydrogen storage cylinder 1 is subjected to hot roll forming treatment.

[0149] (6) Using the coated inter-cylinder connector 2, install two coated hydrogen storage cylinders 1.

[0150] (7) Use hot melt welding technology to repair the gap between the adjacent hydrogen storage cylinder 1 and the cylinder connection 2 to obtain a shorter hydrogen storage well.

[0151] The shorter hydrogen storage well obtained in Example 2 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0152] Example 3

[0153] (1) The inner walls of the single hydrogen storage cylinder 1 and the inter-cylinder connector 2 are respectively subjected to sandblasting to remove rust and roughen the surface;

[0154] The hydrogen storage cylinder 1 is assembled with inter-cylinder connectors 2 at its two opposite axial ends to form a composite assembly;

[0155] (2) The inner wall of the composite component is subjected to overall hot rotational molding to form a coating with a thickness of 1.5 mm.

[0156] Specifically, a thermoplastic material is placed inside the composite component, and both ends of the composite component are sealed; the thermoplastic material is a mixture of 94% HDPE polymer powder, 1% BHA antioxidant, and 5% calcium stearate lubricant.

[0157] The composite component is rotated at a speed of 120 r / min and subjected to hot oil immersion heating treatment until the temperature of the composite component is 20°C higher than the melting point of the hot rotomolded material.

[0158] Keep the temperature and rotate for 40 minutes until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0159] While maintaining rotation, a silicone bag is inserted into the composite component and air at 90°C is introduced to expand the silicone bag and fill the cavity of the composite component. The pressure is then maintained at 0.1 MPa, and the component is then connected to air for natural cooling to 50°C.

[0160] Stop rotating, cool, and remove the seal.

[0161] (3) Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component;

[0162] Specifically, a V-shaped groove is formed by cutting a hot-rolled coating along the circumferential direction on the axial contact surface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1. The angle of the V-shaped groove is 120°.

[0163] (4) Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2;

[0164] (5) Following the same hot roll forming process as described above, another single hydrogen storage cylinder 1 is subjected to hot roll forming treatment.

[0165] (6) Using the coated inter-cylinder connector 2, install two coated hydrogen storage cylinders 1.

[0166] (7) Use hot melt welding technology to repair the gap between the adjacent hydrogen storage cylinder 1 and the cylinder connection 2 to obtain a shorter hydrogen storage well.

[0167] The shorter hydrogen storage well obtained in Example 3 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0168] Example 4

[0169] (1) The inner walls of the single hydrogen storage cylinder 1 and the inter-cylinder connector 2 are respectively subjected to sandblasting to remove rust and roughen the surface;

[0170] The hydrogen storage cylinder 1 is assembled with inter-cylinder connectors 2 at its two opposite axial ends to form a composite assembly;

[0171] A primer is sprayed onto the inner wall of the composite component. The primer is a mixed solvent of maleic acid dissolved in decahydronaphthalene, wherein the total amount of maleic acid and xylene in the primer sprayed onto the inner wall of the composite component is 8 g / m³. 2 The mass ratio of maleic acid to xylene is 1:1.

[0172] (2) The inner wall of the composite component is subjected to overall hot rotational molding to form a coating with a thickness of 1.5 mm.

[0173] Specifically;

[0174] The thermoplastic material is placed inside the composite component, and both ends of the composite component are sealed; the thermoplastic material is a mixture of 94% HDPE polymer powder, 1% BHA antioxidant, and 5% calcium stearate lubricant.

[0175] The composite component is rotated at a speed of 150 r / min and subjected to vertical heating with an open flame until the temperature of the composite component is 10°C higher than the melting point of the hot rotomolded material.

[0176] Keep the temperature and rotate for 60 minutes until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0177] Stop rotating, cool, and remove the seal.

[0178] (3) Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component;

[0179] Specifically, a V-shaped groove is formed by cutting a hot-rolled coating along the circumferential direction on the axial contact surface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1. The angle of the V-shaped groove is 90°.

[0180] (4) Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2;

[0181] (5) Following the same hot roll forming process as described above, another single hydrogen storage cylinder 1 is subjected to hot roll forming treatment.

[0182] (6) Using the coated inter-cylinder connector 2, install two coated hydrogen storage cylinders 1.

[0183] (7) Use hot melt welding technology to repair the gap between the adjacent hydrogen storage cylinder 1 and the cylinder connection 2 to obtain a shorter hydrogen storage well.

[0184] The shorter hydrogen storage well obtained in Example 4 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0185] Example 5

[0186] Example 5 uses the same hot rotational molding process as Example 1 to form a shorter hydrogen storage well, which includes two hydrogen storage cylinders and an inter-cylinder connector 2.

[0187] Compared to Example 1, Example 5 only changed the primer formulation. In Example 5, the primer only included decahydronaphthalene, and the amount of decahydronaphthalene in the primer sprayed on the inner wall of the composite component was 10 g / m². 2 .

[0188] The shorter hydrogen storage well obtained in Example 5 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0189] Example 6

[0190] Example 6 uses the same hot rotational molding process as Example 1 to form a shorter hydrogen storage well, which includes two hydrogen storage cylinders and an inter-cylinder connector 2.

[0191] Compared to Example 1, Example 6 only changed the primer formulation. In Example 6, the primer consisted only of an aqueous solution of maleic acid, and the amount of maleic acid in the primer sprayed on the inner wall of the composite component was 10 g / m³. 2 .

[0192] The shorter hydrogen storage well obtained in Example 6 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0193] Example 7

[0194] Example 7 uses the same hot rotational molding process as Example 1 to form a shorter hydrogen storage well, which includes two hydrogen storage cylinders and an inter-cylinder connector 2.

[0195] Compared to Example 1, Example 7 only changed the ratio of maleic acid and decahydronaphthalene in the primer material formulation.

[0196] in,

[0197] In the primer formulation provided in Example 7-1, the mass ratio of maleic acid to decahydronaphthalene is 3:1, and the total amount of maleic acid and decahydronaphthalene in the primer for inner wall spraying is 10 g / m². 2 .

[0198] In the primer formulation provided in Example 7-2, the mass ratio of maleic acid to decahydronaphthalene is 2:1, and the total amount of maleic acid and decahydronaphthalene in the primer for inner wall spraying is 10 g / m². 2 .

[0199] In the primer formulations provided in Examples 7-3, the mass ratio of maleic acid to decahydronaphthalene is 0.5:1, and the total amount of maleic acid and decahydronaphthalene in the primer for inner wall spraying is 10 g / m². 2 .

[0200] In the primer formulations provided in Examples 7-4, the mass ratio of maleic acid to decahydronaphthalene is 0.3:1, and the total amount of maleic acid and decahydronaphthalene in the primer for inner wall spraying is 10 g / m². 2 .

[0201] The shorter hydrogen storage well obtained in Example 7 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0202] Example 8

[0203] Example 8 uses the same hot rotational molding process as Example 1 to form a shorter hydrogen storage well, which includes two hydrogen storage cylinders and an inter-cylinder connector 2.

[0204] Compared to Example 1, Example 8 performed nickel plating on the inner surface of the sandblasted hydrogen storage well before applying the primer. The specific operation process is illustrated in the embodiment of Chinese Patent CN 114182240 A – A Hydrogen Storage Container Hydrogen Storage Well Inner Wall Hydrogen Barrier Process.

[0205] The shorter hydrogen storage well obtained in Example 8 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0206] Example 9

[0207] (1) The inner walls of the single hydrogen storage cylinder 1 and the inter-cylinder connector 2 are respectively subjected to sandblasting to remove rust and roughen the surface;

[0208] The hydrogen storage cylinder 1 is assembled with inter-cylinder connectors 2 at its two axially opposite ends to form a composite assembly; the inner surface of the hydrogen storage well after sandblasting is subjected to nickel plating surface treatment. The specific operation process is illustrated in the embodiment of Chinese Patent CN 114182240 A – A Hydrogen Storage Container Hydrogen Storage Well Inner Wall Hydrogen Barrier Process.

[0209] A primer material, which is a xylene solvent, is sprayed onto the inner wall of the composite component, wherein the amount of xylene in the primer material sprayed onto the inner wall of the composite component is 10 g / m³. 2 .

[0210] (2) The inner wall of the composite component is subjected to overall hot rotational molding to form a coating with a thickness of 1.5 mm.

[0211] Specifically, a thermoplastic material is placed inside the composite component, and both ends of the composite component are sealed; the thermoplastic material, by weight percentage, comprises 93% polymer PA6 powder, 1% antioxidant, 5% lubricant, and 1% compatibilizer. Figure 1 As shown, the hydrogen storage cylinder 1 and the cylinder connector 2 are connected by threads. The other end of the cylinder connector 2 is connected to a plug 4. The plug 4 is provided with an external thread that matches the internal thread of the cylinder connector 2.

[0212] The composite component is rotated at a speed of 100 r / min and subjected to vertical heating with an open flame. The temperature of the composite component is 270°C, and the temperature is maintained at 270 ±5 °C by adjusting the flame size.

[0213] Keep the temperature and rotate for 60 minutes until a hot roll coating is formed on the inner wall of the composite component, then stop heating;

[0214] While maintaining rotation, insert a silicone bag into the composite component and introduce air at 100°C. After the silicone bag expands and fills the cavity of the composite component, maintain the pressure for 8 minutes at a pressure of 0.2 MPa, and then allow it to cool naturally to 50°C.

[0215] Stop rotating, cool, and remove the seal.

[0216] (3) Cut the hot-rolled coating at the connection point 3 between the hydrogen storage cylinder and the cylinder connector in the composite component;

[0217] Specifically, on both sides of the interface between the inter-cylinder connector 2 and the hydrogen storage cylinder 1, grooves are cut circumferentially to form grooves symmetrical about the perpendicular line of the interface. The grooves are V-shaped in axial section, and the angle of the V-shaped grooves is 90°.

[0218] (4) Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder 1 and a coated inter-cylinder connector 2;

[0219] (5) Following the same hot roll forming process as described above, another single hydrogen storage cylinder 1 is subjected to hot roll forming treatment.

[0220] (6) Using the coated inter-cylinder connector 2, install two coated hydrogen storage cylinders 1.

[0221] (7) Use hot melt welding technology to repair the gap between the adjacent hydrogen storage cylinder 1 and the cylinder connection 2 to obtain a shorter hydrogen storage well.

[0222] The shorter hydrogen storage well obtained in Example 9 was subjected to performance tests according to the test methods in Tests 2-4, and the test results are shown in Table 1.

[0223] Test 2

[0224] Uniformity test:

[0225] Testing process: The protective coating on the inner wall of the hydrogen storage well obtained by hot roller coating was sampled and tested. The test sample was a circular piece with a diameter of 3±0.5 cm. The number of samples taken from different positions was ≥3 pieces. The thickness was tested and the average value was taken. The coating uniformity data was obtained by calculating the thickness error.

[0226] Test 3

[0227] Peel resistance test.

[0228] Testing process: Sampling tests were conducted at different locations in accordance with Appendix K of the national standard GB / T23257 / ISO 2411:2020. The testing equipment was a portable peel strength tester. The test results are the peel strength of the coating, in N / cm.

[0229] Test 4

[0230] Samples were taken from the well body and analyzed for hydrogen permeability according to GB / T 42610-2023.

[0231] Table 1

[0232]

[0233] As can be seen from the test results in Table 1, the technical solution of this application can form a highly continuous integral coating with high resistance to hydrogen embrittlement and a low hydrogen permeability coefficient. Simultaneously, the hot-rolled coating achieves high uniformity and peel resistance, showing a significant improvement in coating uniformity and peel resistance compared to existing spraying or winding processes. The test results of Examples 1-4 show that the primer process and the addition of an inflatable silicone bag for pressure maintenance during hot-rolling can improve the overall performance of the coating to a certain extent. Examples 5-8 show that when maleic acid and organic solvents are coated on the inner wall of the composite component, maleic acid, as a bonding intermediate, can form a graft with the inner wall surface of the composite component. Decahydronaphthalene and / or xylene can dissolve a small amount of hot-rolled coating material and penetrate into the gaps in the metal surface. The synergistic effect of both helps increase the bonding force between the hot-rolled coating and the inner wall surface of the hydrogen storage well structure. To a certain extent, during dynamic hot-rolling, the uniformity and continuity of the coating are improved, enhancing the resistance to hydrogen embrittlement. By rationally controlling the mass ratio of maleic acid to organic solvent and the total amount used per unit area, the peel resistance of the hot rotomolded coating on the inner wall of the composite component can be significantly improved, and the uniformity of the hot rotomolded coating can be increased.

[0234] The test results from Examples 1 and 8-9 show that applying nickel plating to the inner surface of the sandblasted hydrogen storage well before primer treatment can reduce the reaction between hydrogen and alloy steel. However, the chemical plating method is cumbersome, requires a large amount of nickel plating solution, and has high environmental costs. It can be used selectively depending on the length of the hydrogen storage well.

[0235] 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 within the protection scope of the present invention.

Claims

1. A method for hot rotational molding of underground hydrogen storage wells, characterized in that, Includes the following steps: S1. Assemble single-section hydrogen storage cylinders and inter-cylinder connectors to form a composite assembly; S2. Perform hot rotational molding on the inner wall of the composite component; S3. Cut the hot-rolled coating at the connection between the hydrogen storage cylinder and the cylinder connector; S4. Disassemble the composite component to obtain a coated single-section hydrogen storage cylinder and a coated inter-cylinder connector; S5. Repeat steps S1-S4; S6. Connect multiple coated hydrogen storage cylinders sequentially using coated cylinder connectors to form a hydrogen storage well. S7. Use hot melt welding technology to repair the gaps in the hot rotomolded coating of adjacent hydrogen storage cylinders and the connecting parts between cylinders, and complete the hot rotomolding of underground hydrogen storage wells.

2. The hot rotational molding method for underground hydrogen storage wells according to claim 1, characterized in that, In S1, in the composite component, inter-tube connectors are assembled at both ends of each section of the hydrogen storage cylinder.

3. The hot rotational molding method for underground hydrogen storage wells according to claim 1, characterized in that, S1 further includes applying a primer to the inner wall of the composite component, the primer material comprising maleic acid and / or an organic solvent, wherein the organic solvent is at least one of decahydronaphthalene and xylene.

4. The hot rotational molding method for underground hydrogen storage wells according to claim 3, characterized in that, The primer material includes maleic acid and an organic solvent. The total amount of maleic acid and organic solvent in the primer material sprayed on the inner wall of the composite component is 5-10 g / m². 2 ; and / or, in the primer material, the mass ratio of maleic acid to organic solvent is 0.5 to 2:

1.

5. The hot rotational molding method for underground hydrogen storage wells according to claim 1, characterized in that, In step S3, a V-shaped groove is formed by circumferentially cutting the hot-rolled coating on the axial contact surface between the inter-cylinder connector and the hydrogen storage cylinder.

6. The hot rotational molding method for underground hydrogen storage wells according to claim 5, characterized in that, The angle of the V-shaped groove is 60° to 120°.

7. The hot rotational molding method for underground hydrogen storage wells according to any one of claims 1-6, characterized in that, The specific operation process of S2 is as follows: Step 1: Place the thermoplastic material inside the composite component and seal both ends of the composite component; Step 2: Rotate the composite component and heat it; Step 3: Keep the component warm and rotate until a hot roll coating is formed on the inner wall of the composite component, then stop heating; Step 4: Stop rotating, allow to cool, and remove the seal.

8. The hot rotational molding method for underground hydrogen storage wells according to claim 7, characterized in that, In step 2, the heating treatment includes open flame heating, hot oil immersion heating, or hot air heating.

9. The hot rotational molding method for underground hydrogen storage wells according to claim 7, characterized in that, In step 2, the composite component is heated to a temperature 0°C to 30°C above the melting point of the hot-rolled material. And / or, The rotational speed of the composite component is 5 r / min to 200 r / min.

10. The hot rotational molding method for underground hydrogen storage wells according to claim 7, characterized in that, In step 3, the heat preservation and rotation time is 20 min to 80 min.

11. The hot rotational molding method for underground hydrogen storage wells according to claim 7, characterized in that, In step 3, after heating is stopped, while maintaining rotation, a silicone bag is inserted into the composite component and inflated, so that the silicone bag expands to fill the cavity of the composite component and is then pressurized.

12. The hot rotational molding method for underground hydrogen storage wells according to claim 11, characterized in that, Air at 80°C to 100°C is introduced into the silicone bag; and / or, the pressure is maintained at 0.1 MPa to 0.3 MPa.

13. An underground hydrogen storage well formed using the hot rotational molding method according to any one of claims 1-12, characterized in that, include: A multi-section hydrogen storage cylinder, the inner wall of which is provided with a hot-rolled coating, and the multiple sections of the hydrogen storage cylinder are arranged in series; Multiple inter-cylinder connectors, the inner wall of which is provided with a hot-rolled coating, are fitted onto the mating ends of two adjacent hydrogen storage cylinders; The hot-rolled coating of the hydrogen storage cylinder and the hot-rolled coating of the cylinder connector form an axially continuous seamless transition zone at the connection point through hot-melt welding.

14. The underground hydrogen storage well according to claim 13, characterized in that, The inter-cylinder connector is a hollow cylindrical structure. An annular boss is provided on the inner side of the inter-cylinder connector, and the annular boss is arranged along the circumference of the inter-cylinder connector. The hydrogen storage cylinder has external threads at both ends, and the cylinder connector has matching internal threads inside. When the external thread and the internal thread are screwed to their limit positions, the hydrogen storage cylinder and the cylinder connector form an abutment at their axial contact points.

15. The underground hydrogen storage well according to claim 14, characterized in that, The hydrogen permeability of the underground hydrogen storage well is ≤50×10⁻⁶. -15 mol. m / (m 2 ·s·Pa), And / or, Peel strength ≥ 65 N / cm And / or, The thickness error of the hot-rolled coating on the inner wall surface is ≤15 micrometers.

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