Large-span buried heat distribution pipeline and construction method thereof

Abstract

The large-span buried heat distribution pipeline comprises an outer sleeve, a working pipe and a heat preservation layer, clamping strips are arranged on the inner wall of the outer sleeve, the clamping strips penetrate through the whole outer sleeve in the axial direction of the outer sleeve, and the multiple clamping strips are evenly distributed along the circumference of the inner wall of the outer sleeve; tension bands are installed on the working pipe at intervals, clamping grooves matched with the clamping strips are formed in the tension bands, and the clamping grooves are connected to the clamping strips in a clamped mode; and the thermal insulation layer is filled between the outer sleeve and the working pipe. A plurality of clamping strips extending in the axial direction of the outer sleeve are arranged on the inner wall of the outer sleeve, so that the tensile strength of the heat distribution pipeline is improved, and pull cracks of the heat distribution pipeline during back dragging are avoided; the working pipe and the outer sleeve are connected through the tension sleeve, the working pipe can slide along the clamping strip through the clamping groove in the tension sleeve when the working pipe is heated to stretch, force generated by stretching is released through the bent pipes at the two ends, and the service life of the working pipe is prolonged. The invention further discloses a construction method of the large-span buried heat distribution pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of heat transport, and in particular to a large-span buried heat pipeline and a construction method thereof. Background Art

[0002] Energy conservation and environmental protection are issues that the whole world has to face. Cogeneration and centralized heating are important measures to promote energy conservation and environmental protection, and pipeline transportation is one of the main ways to transport heat. The traditional excavation of the road surface for the construction of heating pipelines requires the destruction of the soil layer above the pipeline, which brings a series of traffic and environmental problems, and is not suitable for the construction of thermal pipelines across rivers. Horizontal directional drilling, as a trenchless construction process, is widely used for its high construction accuracy, high speed, and controllable direction. It can cross roads and rivers without affecting road transportation and has minimal impact on the environment, so it has been widely used.

[0003] However, for the trenchless construction of large-span buried thermal pipelines, due to the long length of large-span buried thermal pipelines, the thermal pipelines are easily torn when being pulled back; and the thermal pipelines form a certain curvature when being pulled back. During operation, the working pipe expands due to heat and generates lateral force toward the outside of the curvature, making the insulation layer outside the curvature thinner, reducing the insulation effect, generating condensation water, and causing damage to the pipeline. Summary of the invention

[0004] The purpose of the present invention is to provide a large-span buried thermal pipeline to solve the technical problems mentioned in the background technology. The purpose of the present invention is achieved through the following technical solutions:

[0005] A large-span buried thermal pipeline comprises an outer sleeve, a working pipe and an insulation layer. The inner wall of the outer sleeve is provided with a clamping strip, which penetrates the entire outer sleeve along the axial direction of the outer sleeve, and a plurality of clamping strips are evenly distributed along the circumference of the inner wall of the outer sleeve; hoops are installed on the working pipe at intervals, and the hoops are provided with clamping grooves matching the clamping strips, and the clamping grooves are clamped on the clamping strips; the insulation layer is filled between the outer sleeve and the working pipe.

[0006] Furthermore, a hard insulation ring is provided between the hoop and the working pipe.

[0007] Furthermore, the outer wall of the working tube is wrapped with a first reflective layer, and a hard insulation ring is sleeved on the outside of the first reflective layer; the outer side of the insulation layer is coated with a second reflective layer, and a hoop is sleeved on the outside of the second reflective layer.

[0008] Furthermore, a drainage mechanism is provided on one side of the thermal pipeline close to the air inlet end.

[0009] Furthermore, the curvature radius of the thermal pipeline is 1200-1500 times the outer diameter of the working pipe.

[0010] Furthermore, the unearthed ends of the thermal pipelines are respectively provided with bent pipes, which include an inner pipe and an outer pipe. The inner pipe is connected to the working pipe, and the outer pipe is connected to the outer casing. The diameter of the outer pipe is larger than the diameter of the outer casing, and the inner pipe is located on the side of the outer pipe close to the thermal pipeline.

[0011] A construction method for a large-span buried thermal pipeline, used for laying any of the thermal pipelines described above, comprises the following steps:

[0012] Step S1, preliminary preparation;

[0013] Step S2, drilling a guide hole;

[0014] Step S3, expanding the hole step by step;

[0015] Step S4, pulling back the pipeline;

[0016] Among them, a protective sleeve is welded at the front end of the thermal pipe before the pipeline is pulled back, and water is injected into the thermal pipe for counterweighting. A one-way valve is installed on the top of the protective sleeve, and the one-way valve can be opened inward.

[0017] Further, step S1 includes:

[0018] Step S11, geological exploration;

[0019] Step S12, measuring and setting out;

[0020] Step S13: Arrange and level the operation site, and put the directional drilling rig and supporting facilities in place;

[0021] Step S14, excavating a starting working pit, a receiving working pit and a mud pool;

[0022] Step S15, preparing mud liquid.

[0023] Furthermore, the pulling force of the pipeline in step S4 is 1.5-3.0 times the calculated pulling force, and the calculation formula of the pulling force F is:

[0024]

[0025] Where:

[0026] f is the friction coefficient between the outer wall of the insulation pipe and the inner wall of the hole, which is generally 0.1-0.3;

[0027] g is the acceleration due to gravity, which is 9.8 m / s 2 ;

[0028] L is the crossing length, m;

[0029] ρ is the drilling fluid density, which is 1204 kg / m 3 ;

[0030] D is the outer diameter of the thermal pipe, m;

[0031] M is the mass of the thermal pipe per unit length, kg / m;

[0032] K is the viscosity coefficient, which is 0.01-0.03.

[0033] The technical solution provided in the embodiments of the present application has at least the following technical effects or advantages:

[0034] 1. By arranging a plurality of clips extending along the axial direction of the outer casing on the inner wall of the outer casing, the tensile strength of the thermal pipeline is increased, and the cracking of the thermal pipeline during the pullback is avoided;

[0035] 2. The working pipe is connected to the outer sleeve by a hoop. On the one hand, the outer sleeve is supported, and the lateral force generated by the working pipe when it is heated and elongated to avoid compression of the insulation layer, thereby ensuring the insulation effect of the insulation layer, reducing the generation of condensed water, and extending the service life of the thermal pipeline; on the other hand, when the working pipe is heated and elongated, it can slide along the card strip through the groove on the hoop, and release the force generated by the elongation through the bent pipes at both ends, thereby extending the service life of the working pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0037] Figure 1 This is an axial cross-sectional view of an embodiment of the present application;

[0038] Figure 2 This is a radial cross-sectional view of an embodiment of the present application;

[0039] Figure 3 This is a schematic diagram of the structure of a hard insulation ring according to an embodiment of the present application;

[0040] Figure 4 This is a schematic diagram of the hoop structure of an embodiment of the present application;

[0041] Figure 5 This is a schematic diagram of the outer sleeve structure of an embodiment of the present application;

[0042] Figure 6 This is a schematic diagram of the connection between the thermal pipeline and the elbow according to an embodiment of the present application.

[0043] Markings in the attached drawings: 1, outer sleeve; 11, clamping strip; 2, working pipe; 3, insulation layer; 4, hard insulation ring; 41, rib; 5, hoop; 51, slot; 6, elbow; 61, inner pipe; 62, outer pipe. DETAILED DESCRIPTION

[0044] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings and specific implementation methods of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] like Figure 1-6 The large-span buried thermal pipeline shown in the figure comprises an outer sleeve 1, a working pipe 2 and an insulation layer 3. The working pipe 2 is coaxially sleeved in the outer sleeve 1, and the insulation layer 3 is filled between the outer sleeve 1 and the working pipe 2. The outer sleeve 1 is a double-sided submerged arc spiral welded pipe, and the outer wall of the outer sleeve 1 is coated with glass fiber through epoxy resin to improve the corrosion resistance of the outer sleeve 1. Figure 5 As shown, four clamping strips 11 are welded to the inner wall of the outer sleeve 1 , and the four clamping strips 11 penetrate the entire outer sleeve 1 along the axial direction of the outer sleeve 1 , and the four clamping strips 11 are evenly distributed on the circumference of the inner wall of the outer sleeve 1 at an interval of 90°.

[0047] like Figure 1-4 As shown, a plurality of hoops 5 are installed at intervals on the working tube 2. The hoops 5 are evenly arranged along the length direction of the working tube 2. Four slots 51 matching the clamping strip 11 are provided on the outer wall of the hoops 5. The slots 51 are gap-assembled on the clamping strip 11. When the working tube 2 is heated and elongated, it can slide along the clamping strip 11 through the slots 51.

[0048] Preferably, a hard insulation ring 4 is installed between the hoop 5 and the working tube 2 to reduce the transfer of heat bridges. Specifically, the hard insulation ring 4 is a semicircular calcium silicate insulation brick, and ribs 41 are arranged on both sides of the outer surface of the semicircular ring. The outer wall of the working tube 2 is wrapped with a first reflective layer of aluminum foil, and the hard insulation ring 4 is tightly assembled on the outside of the first reflective layer. The insulation layer 3 is high-temperature glass wool, and the high-temperature glass wool is filled between two adjacent hard insulation rings 4. The outer side of the insulation layer 3 is wrapped with a second reflective layer, and the first reflective layer covers the outer side of the hard insulation ring 4. The hoop 5 is two semicircular ring structures, and the hoop 5 is bolted and fixed between the two ribs 41 of the hard insulation ring 4, so as to achieve the fixation of the hard insulation ring 4.

[0049] The working pipe and the outer sleeve are connected by a hoop. On the one hand, the outer sleeve is supported, and the lateral force generated by the elongation of the working pipe due to heat avoids compression of the insulation layer, thereby ensuring the insulation effect of the insulation layer, reducing the generation of condensed water, and extending the service life of the thermal pipeline; on the other hand, when the working pipe is elongated due to heat, it can slide along the card strip through the groove on the hoop and release the force generated by the elongation through the bent pipes at both ends, thereby extending the service life of the working pipe.

[0050] Preferably, a drain mechanism (not shown) is provided on one side of the thermal pipeline close to the air inlet end to timely drain the condensed water and prevent the condensed water from gathering at the lowest point of the thermal pipeline. The curvature radius of the thermal pipeline is 1200-1500 times the outer diameter of the working pipe 2.

[0051] like Figure 6 As shown, the unearthed ends of the thermal pipelines are respectively provided with elbows 6, which include an inner pipe 61 and an outer pipe 62, the inner pipe 61 is connected to the working pipe 2, the outer pipe 61 is connected to the outer casing 1, and the thermal insulation layer 3 covers the inner pipe 61 and the working pipe 2. The diameter of the outer pipe 62 is larger than the diameter of the outer casing 1, and the inner pipe 61 is located on the side of the outer pipe 62 close to the thermal pipeline. When the working pipe 2 is heated and elongated, the inner pipe 61 moves outward, thereby providing space for the elongation of the working pipe 2.

[0052] Example 2

[0053] A construction method for a large-span buried thermal pipeline comprises the following steps:

[0054] Step S1: Preliminary preparation, specifically including:

[0055] Step S11, geological exploration: survey and measure the construction site, and draw a horizontal guide drilling construction plane and cross-section diagram;

[0056] Step S12, measurement and layout: plan the area of ​​the entry and exit operation areas and the installation space of the equipment according to the design drawings and the specific conditions of the construction site;

[0057] Step S13: Level the operation site according to the plan and build a temporary road to facilitate the placement of the directional drilling rig and supporting facilities;

[0058] Step S14, excavating a starting working pit, a receiving working pit and a mud pool;

[0059] Step S15, preparing mud liquid: the ingredients of the mud liquid usually include water, bentonite, industrial alkali, sodium carboxymethyl cellulose, polyacrylamide, vegetable gum, etc. The formula of the mud liquid should be adjusted according to the changes in the soil quality of the formation during drilling, and the pH value should be controlled at 8-10.

[0060] During the drilling process, the main function of the mud is to remove sand and mud, promote the formation and stability of the hole, and cool the drill bit and drill rod; during the backhaul process, the main function of the mud is to lubricate and protect the pipeline.

[0061] Step S2, drilling a guide hole:

[0062] Before drilling, complete all preparations such as installation and commissioning of the drilling rig to ensure that the system is operating normally. After cleaning the drill rod and drill bit, conduct trial drilling in strict accordance with the design drawings and construction acceptance specifications. After drilling two drill rods, check the operation of each part. After all parameters are normal, drill in order.

[0063] The position of the drill bit is corrected every 6 meters to ensure the accuracy of the crossing, and adjustments are made according to the situation to ensure that the guide hole conforms to the designed curve. The drill rod adopts a thickened drill rod, and the drill bit adopts a three-cone tungsten carbide drill bit; the direction control equipment adopts a magnetic wired direction control system, and uses a ground beacon system for accurate tracking and positioning to ensure the excavation position is accurate.

[0064] Step S3, step-by-step hole expansion:

[0065] After the pilot hole operation is completed, determine whether the pilot hole curve meets the requirements of the expansion and pullback operation, remove the drill bit, install the reamer, and connect the drill rod to the reamer to start reaming. The size of the reamer is gradually increased, and the size of the last reamer is 130%-150% of the outer diameter of the thermal pipeline.

[0066] Step S4, pulling back the pipeline;

[0067] Among them, a protective sleeve is welded at the front end of the thermal pipeline before the pipeline is pulled back. The protective sleeve covers the outside of the front end of the thermal pipeline. A one-way valve is installed on the top of the protective sleeve, and the one-way valve can be opened inward. Water is injected into the thermal pipeline for counterweight, so that the thermal pipeline is suspended in the hole of the bracket to prevent the thermal pipeline from being subjected to upward buoyancy and friction with the top wall of the hole, thereby increasing the resistance of pulling back.

[0068] A one-way valve is installed on the top of the protective sleeve, which can be opened when the thermal pipe is pulled back upward to prevent the water in the thermal pipe from forming a piston effect and causing the thermal pipe to be compressed and deformed.

[0069] The pull-back force of the pipeline is 1.5-3.0 times the calculated pull-back force. The calculation formula of the pull-back force F is:

[0070]

[0071] Where:

[0072] f is the friction coefficient between the outer wall of the insulation pipe and the inner wall of the hole, which is generally 0.1-0.3;

[0073] g is the acceleration due to gravity, which is 9.8 m / s 2 ;

[0074] L is the crossing length, m;

[0075] ρ is the drilling fluid density, which is 1204 kg / m 3 ;

[0076] D is the outer diameter of the thermal pipe, m;

[0077] M is the mass of the thermal pipeline per unit length, kg / m;

[0078] K is the viscosity coefficient, which is 0.01-0.03.

[0079] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0080] 1. By arranging a plurality of clips extending along the axial direction of the outer casing on the inner wall of the outer casing, the tensile strength of the thermal pipeline is increased, and the cracking of the thermal pipeline during the pullback is avoided;

[0081] 2. The working pipe is connected to the outer sleeve by a hoop. On the one hand, the outer sleeve is supported, and the lateral force generated by the working pipe when it is heated and elongated to avoid compression of the insulation layer, thereby ensuring the insulation effect of the insulation layer, reducing the generation of condensed water, and extending the service life of the thermal pipeline; on the other hand, when the working pipe is heated and elongated, it can slide along the card strip through the groove on the hoop, and release the force generated by the elongation through the bent pipes at both ends, thereby extending the service life of the working pipe.

[0082] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A large-span buried thermal pipeline, characterized in that: include: An outer sleeve, wherein the inner wall of the outer sleeve is provided with a clamping strip, the clamping strip runs through the entire outer sleeve along the axial direction of the outer sleeve, and a plurality of the clamping strips are evenly distributed along the circumference of the inner wall of the outer sleeve; A working tube, on which hoops are installed at intervals, and on which a slot matching the clamping strip is formed, and the clamping slot is clamped on the clamping strip; A heat-insulating layer is filled between the outer sleeve and the working tube.

2. A large-span buried thermal pipeline according to claim 1, characterized in that: A hard insulation ring is arranged between the hoop and the working pipe.

3. A large-span buried thermal pipeline according to claim 2, characterized in that: The outer wall of the working tube is wrapped with a first reflective layer, and the hard insulation ring is sleeved on the outer side of the first reflective layer; the outer side of the insulation layer is covered with a second reflective layer, and the hoop is sleeved on the outer side of the second reflective layer.

4. The large-span buried thermal pipeline according to claim 1, characterized in that: A water-draining mechanism is arranged on one side of the thermal pipeline close to the air inlet end.

5. The large-span buried thermal pipeline according to claim 1, characterized in that: The curvature radius of the thermal pipeline is 1200-1500 times the outer diameter of the working pipe.

6. The large-span buried thermal pipeline according to claim 1, characterized in that: The unearthed ends of the thermal pipelines are respectively provided with bent pipes, which include an inner pipe and an outer pipe. The inner pipe is connected to the working pipe, and the outer pipe is connected to the outer casing. The diameter of the outer pipe is larger than the diameter of the outer casing, and the inner pipe is located on the side of the outer pipe close to the thermal pipeline.

7. A construction method for a large-span buried thermal pipeline, used for laying the thermal pipeline according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, preliminary preparation; Step S2, drilling a guide hole; Step S3, expanding the hole step by step; Step S4, pulling back the pipeline; Among them, a protective sleeve is welded at the front end of the thermal pipeline before the pipeline is pulled back, and water is injected into the thermal pipeline for counterweighting. A one-way valve is installed on the top of the protective sleeve, and the one-way valve can be opened inward.

8. The construction method of a large-span buried thermal pipeline according to claim 7, characterized in that: The step S1 comprises: Step S11, geological exploration; Step S12, measuring and setting out; Step S13: Arrange and level the operation site, and put the directional drilling rig and supporting facilities in place; Step S14, excavating a starting working pit, a receiving working pit and a mud pool; Step S15, preparing mud liquid.

9. The construction method of a large-span buried thermal pipeline according to claim 7, characterized in that: The pulling force of the pipeline in step S4 is 1.5-3.0 times the calculated pulling force. The calculation formula of the pulling force F is: Where: f is the friction coefficient between the outer wall of the insulation pipe and the inner wall of the hole, which is generally 0.1-0.3; g is the acceleration due to gravity, which is 9.8 m / s 2 ; L is the crossing length, m; ρ is the drilling fluid density, which is 1204 kg / m 3 ; D is the outer diameter of the thermal pipe, m; M is the mass of the thermal pipeline per unit length, kg / m; K is the viscosity coefficient, which is 0.01-0.03.

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