Cryogenic liquefied air filled tube for rock breaking

Abstract

This invention provides a liquid-filled pipe for cryogenic liquefied air-powered rock breaking, comprising a flexible inner tube, a tube section made of a high-molecular polymer that maintains toughness and elasticity at cryogenic liquefied air temperatures; a reinforcing layer tightly covering the outer surface of the flexible inner tube to resist radial deformation of the tube section; and a protective layer covering the outside of the reinforcing layer to resist external mechanical wear. The three-layer structure is integrally formed through a hot-melt composite process. It combines impact resistance, fatigue resistance, reliable sealing, and ease of construction in cryogenic environments, fundamentally reducing leakage risks and maintenance needs, and improving the safety and efficiency of rock breaking technology.

Description

Technical Field

[0001] This utility model relates to the field of cryogenic liquefied air energy rock breaking technology, and in particular to a liquid filling pipe for cryogenic liquefied air energy rock breaking. Background Technology

[0002] In the fields of hard rock fracturing, mining, and special geological engineering construction, cryogenic liquefied air fracturing technology has significant advantages such as safety, environmental friendliness, and no sparks. The core principle of this technology is to transport liquefied air through a dedicated pipeline and inject it into pre-drilled rock fissures. The liquid medium rapidly absorbs heat and vaporizes within the confined space, generating enormous fracturing pressure that breaks the rock mass. Currently, the key component responsible for transporting this cryogenic medium—the filling pipe—is generally made of stainless steel, alloy steel, and other metal materials. While metal pipes possess high pressure resistance, under extreme low-temperature conditions, their inherent cryogenic brittleness leads to a sharp decrease in impact toughness and fatigue strength. This makes them prone to brittle fracture or seal failure under repeated use, uneven terrain, or external forces, causing cryogenic medium leakage. This not only interrupts construction but also poses serious safety risks. Furthermore, metal pipelines are heavy and lack flexibility, making their deployment, winding, and transportation extremely difficult in complex and rugged construction sites, resulting in low construction efficiency. Frequent maintenance and replacement further increase construction costs and safety risks.

[0003] Therefore, there is an urgent need to develop a new type of liquid-filled pipe that can work stably in ultra-low temperature environments and has excellent flexibility, impact resistance and reliable sealing, in order to overcome the inherent defects of metal pipes and improve the construction safety, efficiency and convenience of ultra-low temperature liquefied air rock breaking technology. Utility Model Content

[0004] The main purpose of this utility model is to provide a liquid filling pipe for rock breaking using ultra-low temperature liquefied air energy, which solves the problems of poor ultra-low temperature integrity and low construction efficiency of the liquid filling pipe.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a liquid filling pipe for rock breaking using ultra-low temperature liquefied air energy, including a flexible inner tube and a tube section made of a high molecular polymer that maintains toughness and elasticity at ultra-low temperature liquefied air temperature; The reinforcing layer is tightly wrapped around the outer surface of the flexible inner tube to resist radial deformation of the tube section; The protective layer, which covers the outside of the reinforcing layer, is used to resist external mechanical wear.

[0006] In the preferred embodiment, the flexible inner tube is made of low-temperature resistant polyurethane material, and its inner wall is a smooth flow channel surface, which is used as a channel for the flow of low-temperature liquids.

[0007] In the preferred embodiment, the reinforcing layer consists of at least one high-strength spiral tightly wound around the outer wall of the flexible inner tube.

[0008] In the preferred embodiment, the high-strength strip material is a polymer fiber bundle layer or a flexible metal wire strip layer, used to maintain the flexibility of the composite tube body formed by the reinforcing layer and the flexible inner tube.

[0009] In the preferred embodiment, the spiral winding angle of the high-strength strip is 75°-90°, forming a high winding angle.

[0010] In the preferred embodiment, the protective layer is a wear-resistant polyurethane layer or a rubber layer.

[0011] In the preferred embodiment, the outer surface of the protective layer is provided with several anti-torsion ridges extending axially.

[0012] In the preferred embodiment, several deformation rings are provided between the reinforcing layer and the protective layer. The deformation rings are made of a polymer material that can shrink at ultra-low temperatures. The shrinkage direction is parallel to the axis of the flexible inner tube and is used to cause contraction deformation when ultra-low temperature liquefied air is passed through the flexible inner tube.

[0013] In the preferred embodiment, the flexible inner tube, the reinforcing layer, and the protective layer are integrally formed by a hot-melt composite process, wherein the reinforcing layer is partially embedded in the adjacent polymer layer during the hot-melt process to form a mechanical interlock.

[0014] In the preferred embodiment, the deformation ring is partially encapsulated and embedded in the molten protective layer during the hot-melt composite process to achieve fixation.

[0015] This invention provides a cryogenic liquefied air-powered rock-breaking filling pipe. It replaces the traditional metal pipe with a flexible polymer inner tube, and combines a reinforcing layer and a protective layer in a composite structure, significantly overcoming the inherent defects of metal pipes under cryogenic conditions. The flexible inner tube is made of cryogenically resistant polyurethane material, maintaining its toughness and elasticity in cryogenic environments, avoiding the risk of brittle fracture caused by the low-temperature brittleness of metal materials. Its smooth inner wall reduces fluid resistance, ensuring efficient delivery of cryogenic liquefied air.

[0016] The reinforcing layer tightly wraps the inner tube with a high-strength tape wound at a high angle, with the winding angle controlled within the range of 75°-90°. This structure resists radial compression deformation while maintaining excellent bending performance due to the material's inherent flexibility and the spiral design. This allows it to adapt to the laying requirements of complex rock fissures, preventing channel blockage caused by tube collapse. The protective layer uses wear-resistant polyurethane or rubber, directly isolating it from external rock friction and mechanical damage, significantly extending its service life. The axial anti-torsion ridges added to its outer surface not only improve the tube's torsional stiffness but also facilitate handling during construction, further ensuring laying stability.

[0017] The added deformation ring, made of a cryogenic shrinkable polymer, is embedded between the reinforcing layer and the protective layer. When cryogenic liquefied air is introduced, the deformation ring contracts axially, causing a local radial bulge in the pipe wall. This creates an interference fit between the pipe body and the inner wall of the joint, significantly improving the connection sealing performance and pull-out resistance. This design effectively solves the problem of joint sealing failure caused by hardening of polymer pipes at low temperatures, avoiding the risk of media leakage.

[0018] The three-layer structure is integrally formed using a hot-melt composite process. Molten polymer material penetrates into the fiber gaps of the reinforcing layer, forming a mechanically interlocking structure upon cooling. This eliminates the need for adhesives that are prone to failure at low temperatures, ensuring interlayer bonding strength and low-temperature reliability. Deformation rings pre-embedded during manufacturing are also fixed using this process, simplifying the production flow. The overall structure is lightweight and flexible, facilitating coiled transportation and downhole installation, significantly reducing handling stress and construction costs.

[0019] In summary, this filling pipe combines impact resistance, fatigue resistance, reliable sealing, and ease of construction in ultra-low temperature environments, fundamentally reducing leakage risks and maintenance needs, and improving the safety and efficiency of rock breaking technology. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the liquid filling tube installation structure of this utility model; Figure 2 This is a cross-sectional view of the filling tube of this utility model; Figure 3 This is a disassembled structural diagram of the filling tube of this utility model; Figure 4 This is a schematic diagram of the deformable annular structure of this utility model.

[0021] In the figure: Flexible inner tube 1; Reinforcing layer 2; Protective layer 3; Anti-torsion ridge 301; Deformation ring 4; Quick connector 5. Detailed Implementation

[0022] Example 1 like Figures 1-4 As shown, a cryogenic liquefied air energy rock-breaking filling pipe includes a flexible inner tube 1 and a tube section made of a high molecular polymer that maintains toughness and elasticity at cryogenic liquefied air temperatures. The reinforcing layer 2 is tightly wrapped around the outer surface of the flexible inner tube 1 to resist radial deformation of the tube section; The protective layer 3, which covers the outside of the reinforcing layer 2, is used to resist external mechanical wear.

[0023] This application uses a flexible inner tube 1 made of low-temperature resistant material to replace the metal filling tube. The preferred material is low-temperature resistant polyurethane (PU), which has superior elastic deformation capacity and resistance to low-temperature brittleness compared to metal, and can adapt to freeze-thaw cycles. Compared to metal tubes, PU tubes are lighter, facilitating transportation, installation, and downhole operations. Their good flexibility makes them easier to bend and lay, adapting to complex drilling trajectories. To adapt to more complex rock fracture trajectories and prevent flattening and blockage of the flow channel during drilling, a reinforcing layer 2 is incorporated to enhance its resistance to radial compression. Since the pipeline will experience vibration and impact due to flow rate surges and friction with the rock fractures and ground surface after liquefied air is introduced, a protective layer 3 is introduced on the outermost layer to prevent wear and breakage. This three-layer composite structure allows the PU filling tube to possess enhanced resistance to compression and wear while maintaining flexibility for easy transportation and installation.

[0024] In the preferred embodiment, the flexible inner tube 1 is made of low-temperature resistant polyurethane material, and its inner wall is a smooth flow channel surface, which is used as a low-temperature liquid flow channel.

[0025] In the preferred embodiment, the reinforcing layer 2 has a structure of at least one high-strength spiral tightly wound around the outer wall of the flexible inner tube 1.

[0026] In the preferred embodiment, the high-strength strip material is a polymer fiber bundle layer or a flexible metal wire strip layer, used to maintain the flexibility of the composite tube body formed by the reinforcing layer 2 and the flexible inner tube 1.

[0027] In the preferred embodiment, the spiral winding angle of the high-strength strip is 75°-90°, forming a high winding angle.

[0028] The second reinforcing layer consists of high-strength polymer fiber tapes, such as aramid fiber Kevlar, ultra-high molecular weight polyethylene fiber Dyneema, or ultra-thin flexible metal tapes, such as annealed stainless steel tapes, tightly spirally wound at a high angle, close to 90° axially. This near-axial winding structure acts like a skeleton for the flexible inner PU tube, effectively resisting radial compressive loads and preventing the tube from collapsing under internal or external pressure or external rock pressure, ensuring a stable flow cross-section. Despite the high winding angle, the use of flexible fiber tapes or thin metal tapes, while maintaining the spiral structure itself, ensures that the entire composite tube retains excellent bending flexibility, facilitating coiling and installation.

[0029] In the preferred embodiment, the protective layer 3 is a wear-resistant polyurethane layer or a rubber layer.

[0030] In the preferred embodiment, the outer surface of the protective layer 3 is provided with a plurality of anti-torsion ridges 301 extending along the axial direction.

[0031] The specialized wear-resistant outer sheath isolates the tube body from direct scraping by the rough hole wall, greatly improving the PU tube's resistance to mechanical damage and extending its service life. Anti-torsion ridges 301 are evenly distributed axially on the outer surface of the composite tube, especially in areas expected to be prone to wear, increasing the surface rigidity of the tube body, assisting in preventing compression, and facilitating gripping and handling during construction.

[0032] In the preferred embodiment, a number of deformation rings 4 are provided between the reinforcing layer 2 and the protective layer 3. The deformation rings 4 are made of polymer materials that can shrink at ultra-low temperatures. Their shrinkage direction is parallel to the axis of the flexible inner tube 1, and they are used to cause contraction deformation when ultra-low temperature liquefied air is passed through the flexible inner tube 1.

[0033] In the preferred embodiment, the flexible inner tube 1, the reinforcing layer 2, and the protective layer 3 are integrally formed by a hot-melt composite process, wherein the reinforcing layer 2 is partially embedded in the adjacent polymer layer during the hot-melt process to form a mechanical interlock.

[0034] In the preferred embodiment, the deformation ring 4 is partially encapsulated and embedded in the molten protective layer 3 during the hot melt composite process to achieve fixation.

[0035] PU (polyurethane) filling tubes have poor resistance to axial pull-out. Their connection mainly relies on the frictional force generated by the radial clamping force of the connector on the tube wall to resist axial tension. At low temperatures, PU hardens and becomes brittle, which may reduce the frictional force. Furthermore, the tube wall is easily damaged under high-pressure radial clamping, causing the tube to be pulled out of the connector. During repeated insertion and removal connections or friction with rough hole walls, the tube end is the first part to be damaged. Once damaged, it will affect the seal. When cutting the required length from the reel, the newly cut tube end is a "bare" end, lacking a reinforcement structure specifically designed for connection, making it difficult to guarantee connection reliability.

[0036] Therefore, the deformation ring 4 structure is introduced. The deformation ring 4 can be set at a certain interval during the manufacturing of the tube body, and at least one convex ring can be included at the end when cutting.

[0037] Without cryogenic liquefied air, the deformation ring 4, as an internal composite structure, does not affect the pipe diameter. During installation, when cutting the required filling pipe length, the cutting position is taken near the deformation ring 4, so that the pipe end inserted into the quick connector 5 has the deformation ring 4 structure. When cryogenic gas is introduced, the deformation ring 4 undergoes axial deformation. Its slight radial deformation is offset by the radial compression resistance of the reinforcing layer 2. However, because its axial deformation is thermally fused with the protective layer 3 during manufacturing, it will cause the pipe section to radially contract, resulting in a pipe diameter bulge. Inside the quick connector 5, regardless of whether the contraction and diameter change position of the deformation ring 4 is at the snap ring or the friction locking ring, the increased pipe diameter will cause a sharp increase in the interference between it and the inner wall of the connector, generating a strong radial sealing pressure, thereby enhancing the locking performance and preventing connection failure due to vibration, pulling, or fluid pulse, which could lead to liquefied air leakage.

[0038] Thermomelactic bonding refers to the process of heating adjacent polymer layers to melt their surfaces, fusing them under pressure, and then cooling them to form a single unit. This avoids the use of adhesives that are prone to failure at low temperatures. In this design, both the flexible inner tube 1 and the protective layer 3 are polymer matrices that can be compatible and fused at thermomelting temperatures. The reinforcing layer 2 uses high-strength polymer fiber tape or extremely thin flexible metal tape. Its fiber weave or wire structure creates gaps in the braided fibers. During the thermomelting process, the molten outer layer of the PU tube and the inner layer of the protective layer penetrate into the fiber gaps of the braided layer. After cooling and solidification, they form a mechanical anchor similar to rivets or tree roots. This bonding method is very reliable at low temperatures and does not rely on chemical adhesives. The braided layer is sandwiched within the molten polymer, greatly restricting its relative movement. The braided structure of the reinforcing layer 2 itself has excellent resistance to loosening and bending deformation, ensuring that the filling tube remains intact after coiling.

[0039] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A liquid filling pipe for cryogenic liquefied air-powered rock breaking, characterized in that: Includes a flexible inner tube (1), a tube segment made of a high molecular polymer that maintains toughness and elasticity at ultra-low temperature liquefied air; The reinforcing layer (2) is tightly wrapped around the outer surface of the flexible inner tube (1) to resist radial deformation of the tube section; The protective layer (3) is wrapped around the outside of the reinforcing layer (2) to resist external mechanical wear.

2. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: The flexible inner tube (1) is made of low-temperature resistant polyurethane material, and its inner wall is a smooth flow channel surface, which is used as a low-temperature liquid flow channel.

3. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: The structure of the reinforcing layer (2) is that at least one high-strength spiral is tightly wound around the outer wall of the flexible inner tube (1).

4. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 3, characterized in that: The high-strength strip material is a polymer fiber bundle layer or a flexible metal wire strip layer, which is used to maintain the flexibility of the composite tube body composed of the reinforcing layer (2) and the flexible inner tube (1).

5. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 3, characterized in that: The high-strength tape has a spiral winding angle of 75°-90°, forming a high winding angle.

6. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: The protective layer (3) is a wear-resistant polyurethane layer or a rubber layer.

7. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: The outer surface of the protective layer (3) is provided with several anti-torsion ridges (301) extending along the axial direction.

8. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: Several deformation rings (4) are provided between the reinforcing layer (2) and the protective layer (3). The deformation rings (4) are made of polymer materials that can shrink at ultra-low temperatures. Their shrinkage direction is parallel to the axis of the flexible inner tube (1) and is used to cause contraction deformation when ultra-low temperature liquefied air is passed through the flexible inner tube (1).

9. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 1, characterized in that: The flexible inner tube (1), the reinforcing layer (2) and the protective layer (3) are integrally formed by hot melt composite process, wherein the reinforcing layer (2) is partially embedded in the adjacent polymer layer during the hot melt process to form a mechanical interlock.

10. The cryogenic liquefied air-powered rock-breaking filling pipe according to claim 9, characterized in that: During the hot melt composite process, the deformation ring (4) is partially encapsulated and embedded in the molten protective layer (3) to achieve fixation.

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