A thermal pipeline lining repair process method based on temperature strain compensation

Abstract

The present invention discloses a repair process method for the inner lining of a thermal pipeline based on temperature strain compensation, which includes a thermal pipeline to be repaired, an external flange connector, a fixed sealing end cover, an inner lining repair pipeline, a pipe diameter reducer, a traction and stretching machine, a compressor, an air inlet hole, a connecting pipeline and an accessory valve. By pre-stretching the inner lining repair pipeline, the present invention can effectively eliminate the influence of the thermal stress on the inner lining pipeline at high temperatures; and an inner lining repair pipeline with an interference fit in pipe diameter size is adopted with the thermal pipeline, and through the method of inflating and expanding the pipe, the inner lining repair pipeline is closely attached to the thermal pipeline to be repaired, preventing the inner lining repair pipeline from shrinking and rebounding when there is no stretching effect.

Description

Technical Field

[0001] The present invention relates to a technology for repairing thermal pipelines, and in particular to a method for repairing the inner lining of thermal pipelines based on temperature strain compensation. Background Technique

[0002] As an important urban public infrastructure, with the continuous development of urbanization in China, the application scope of the thermal pipeline network is becoming more and more extensive. However, at the same time, the number of pipelines reaching the end of their service life is gradually increasing, resulting in serious problems such as ground collapse, pipeline siltation, and surface waterlogging, bringing serious energy waste and social environmental problems. At present, the trenchless pipeline renewal and repair technology is widely used in the repair projects of steam pipelines, drain pipelines, and gas pipelines due to its advantages of high repair efficiency, low maintenance cost, and small environmental impact.

[0003] However, based on the strict requirements of high temperature and high pressure, waterproofing and rust prevention for thermal pipelines, the repair technology still mainly relies on traditional repair by welding and pipe replacement. The repair process requires the heating to be stopped, and even a large amount of earthwork needs to be excavated. The construction period is long, the cost is high, and the impact is large. The pipeline inner lining repair technology belongs to semi-structural repair. The inner lining pipeline adopted relies on the original pipeline structure and only needs to bear the external hydrostatic pressure within the design service life. The external soil pressure and dynamic load are still supported by the original pipeline. The repair cost is low, the service life is long, and the one-time insertion distance can reach 500-1000m. It can pass through elbows with an angle ≤ 15°, and the applicable range is relatively wide. How to adopt trenchless repair technology, especially the pipeline inner lining repair technology, in the repair process of thermal pipelines has broad application prospects.

[0004] The lining repair materials mainly include organic coatings, cement slurries, polyethylene, stainless steel, etc., and their properties will change greatly with the change of environmental temperature. Especially for non-metallic lining repair materials represented by high molecular polymers, in high-temperature thermal pipelines, strain may occur due to temperature rise, resulting in extrusion deformation, thus affecting the sealing performance of pipeline connections and reducing the stability of pipeline operation. Chinese Patent CN 106958718 A proposes a pipeline lining repair method, which can form a lining on the inner wall of the pipeline without full-line excavation, shortening the repair cycle of the pipeline and solving the problem of anti-corrosion repair of the corroded pipeline that needs to be lined. Chinese Patent CN112780878A proposes a process for repairing old pipelines by the pipeline lining insertion method, setting connection ports at both ends of the lined pipeline to fix it with the pipeline to be repaired, avoiding gaps between pipelines after repair, and solving the problem of short service life of pipelines after repair by the existing lining insertion method. However, the above patents do not consider the impact of the change of the performance of the lining repair material with temperature on the repair effect. More importantly, they do not solve the problem that in a high-temperature and high-pressure working environment, due to the different thermal strains of the working pipe and the repaired pipeline, the inconsistent thermal expansion elongation results in interface or internal bulging, thus accelerating the failure of the repair material and unable to ensure the safe and stable operation of the pipeline.

[0005] Therefore, while ensuring the reliability of the pipeline material itself, the lining repair technology for thermal pipelines also needs to solve the reliability problem of the thermal expansion and contraction effect caused by temperature in installation, so as to better ensure the safe and stable operation of the repaired pipeline, reduce the maintenance cost, and improve the social and environmental benefits, which has important engineering significance. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above problems and provide a lining repair process method for thermal pipelines based on temperature strain compensation.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A lining repair process method for thermal pipelines based on temperature strain compensation, which uses a lined pipeline for repair (4), a pipe reducer (5), a traction and stretching machine (6), and a compressor (7) to repair the thermal pipeline to be repaired (1); wherein, external flange connectors (2) are welded at both ends of the thermal pipeline to be repaired (1), and an air inlet hole (8) is provided at the outlet end of the lined pipeline for repair (4);

[0009] The lining repair process method includes five processes: pipe reduction and insertion, edge bending and fixing, pre-stretching, inflating and expanding the pipe, and edge bending and connection. The specific processes are as follows:

[0010] First, use a pipe shrinking machine (5) to shrink the diameter of the lining repair pipe (4) whose outer diameter is larger than the inner diameter of the damaged heat pipe (1) so that it can be inserted into the damaged heat pipe (1). Then, under the traction of a traction and stretching machine (6), the shrunk lining repair pipe (4) is pulled through the cleaned damaged heat pipe (1), with its inlet end and outlet end extending out of the ends of the damaged heat pipe (1) respectively, thus completing the shrinking and insertion process;

[0011] After the inlet end of the shrunk lining repair pipe (4) is turned and folded, it is connected to the external flange connector (2) at the same end by caulking and sealing through a fixed sealing end cover (3), so that the inlet end of the lining repair pipe (4) is kept airtight, thus completing the caulking and fixing process;

[0012] With the inlet end of the lining repair pipe (4) fixed, use the traction and stretching machine (6) to stretch and extend the outlet end of the lining repair pipe (4), and the pre-stretching amount is the strain caused by the temperature difference between the working temperature and the ambient temperature of the lining repair pipe (4), thus completing the pre-stretching process;

[0013] Use a compressor (7) to inflate the pre-stretched lining repair pipe (4) through an air inlet hole (8) to expand the pipe, realizing the restoration of the lining repair pipe (4). After restoration, the lining pipe and the heat pipe are in an interference fit, so that the outer wall of the lining repair pipe (4) is closely attached to the inner wall surface of the damaged heat pipe (1). After removing the traction and stretching machine (6), the lining repair pipe (4) cannot shrink and rebound, thus completing the inflating and expanding process;

[0014] Cut the redundant part of the outlet end of the lining repair pipe (4) that extends out of the damaged heat pipe (1), and only keep the folded edge section for caulking and fixing; Caulk and fix the remaining folded edge section of the lining repair pipe (4) with the external flange connector (2) at the same end, and reconnect the two ends of the damaged heat pipe (1) with the lining repair pipe (4) to the heat pipe network through flanges, thus completing the caulking connection process.

[0015] Preferably, during the pre-stretching process, the pre-stretching amount Δl of the lining repair pipe (4) = ΔTLσ, where ΔT is the temperature difference between the actual working temperature and the ambient temperature of the lining repair pipe (4), L is the length of the lining repair pipe (4) before stretching, and σ is the thermal strain of the lining repair pipe (4).

[0016] Preferably, the outer diameter of the lining repair pipe (4) after restoration and the inner diameter of the damaged heat pipe (1) meet the dimensional requirements of an interference fit, and it should be ensured that the friction force between the inner wall of the damaged heat pipe (1) and the lining repair pipe (4) in the interference fit state is greater than the stress shrinkage force of the lining repair pipe (4).

[0017] Preferably, before reconnecting the two ends of the damaged heat pipeline (1) with the lined repair pipeline (4) to the heat pipeline network through flanges again, the fixed sealing end cover (3) at the inlet end needs to be removed in advance.

[0018] Preferably, the diameter reduction methods of the lined repair pipeline (4) include U-shaped flanging diameter reduction and O-shaped diameter reduction.

[0019] Preferably, the flanging methods include fusion welding flanging and flange flanging.

[0020] Preferably, the working pressure used by the compressor (7) to inflate and expand the lined repair pipeline (4) is 0.12 - 0.3 Mpa.

[0021] Preferably, the damaged heat pipeline (1) to be repaired is obtained by excavating operation pits on both sides of the damaged position in the heat pipeline and performing pipe cutting treatment.

[0022] Preferably, the external flange connection head (2) is sleeved at the two pipe cutting positions by hot melt welding.

[0023] Preferably, after the damaged heat pipeline (1) to be repaired is reconnected to the heat pipeline network, the repaired pipeline needs to be pressure tested, and after the pressure test is qualified, the operation pit is refilled.

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] (1) By pre-stretching the lined repair pipeline, the present invention can eliminate the influence of the thermal stress on the lined pipeline at high temperatures during the application of the heat pipeline, and solve problems such as bulging and edge lifting caused by thermal expansion and contraction during installation and use.

[0026] (2) The present invention uses an external flange connection and a fixed sealing end cover to fix one end of the lined repair pipeline, and uses a traction stretching machine to stretch the other end, so that the stretching strain Δl can be accurately controlled.

[0027] (3) The present invention uses a lined repair pipeline with an interference fit in pipe diameter size and the heat pipeline, and through the method of inflating and expanding the pipe, the lined repair pipeline is tightly attached to the damaged heat pipeline, preventing the lined repair pipeline from shrinking and rebounding when there is no tensile force. Brief Description of the Drawings

[0028] Figure 1 is a schematic diagram of the working process flow of the heat pipeline lining repair process method;

[0029] Figure 2 is a schematic diagram of a heat pipeline lining repair system based on temperature strain compensation;

[0030] Figure 3It is a schematic diagram of the pipe edge bending and sealing fixed structure;

[0031] Figure 4 It is a schematic diagram of the cross-section of the pipeline before and after inflating and expanding the pipe.

[0032] In the figure: the heat pipeline to be repaired 1, the external flange connector 2, the fixed sealing end cover 3, the lining repair pipeline 4, the pipe diameter reducing machine 5, the traction and stretching machine 6, the air compressor 7, the air inlet hole 8. Specific implementation manners

[0033] To make the above objects, features and advantages of the present invention more obvious and understandable, the specific implementation manners of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined correspondingly without conflict.

[0034] As Figure 1 shown, the present invention provides a heat pipeline lining repair process method based on temperature strain compensation, and the form of the repair system adopted is as Figure 2 shown. In this process method, the lining repair pipeline 4, the pipe diameter reducing machine 5, the traction and stretching machine 6, and the air compressor 7 are used to repair the heat pipeline 1 to be repaired. Among them, external flange connectors 2 are welded to both ends of the heat pipeline 1 to be repaired, and an air inlet hole 8 is provided at the outlet end of the lining repair pipeline 4.

[0035] It should be noted that the heat pipeline 1 to be repaired in the present invention refers to the damaged section to be repaired in the heat pipeline network. Before the repair treatment of the present invention, it is often connected in the heat pipeline network. In actual application, the damaged position of the pipeline in the heat pipeline network can be determined first, and then operation pits are excavated on both sides of the damaged position in the heat pipeline and the pipe is cut off, so as to obtain a section of heat pipeline 1 to be repaired. At this time, the heat pipeline 1 to be repaired obtained does not contain the external flange connector 2, so the corresponding external flange connector 2 needs to be additionally sleeved at the two pipe cutting positions by hot melt welding. Then the lining repair process method as Figure 1 shown can be started. The specific material of the lining repair pipeline 4 in the present invention is not limited, and can be determined by the actual pipeline material. A non-metallic lining repair material with a certain elasticity can be used, such as a polyethylene pipeline.

[0036] The lining repair process method of the present invention includes five processes: diameter reduction and insertion, edge bending and fixing, pre-stretching, inflating and expanding the pipe, and edge bending connection. The specific implementation manners of these five processes will be described in detail below.

[0037] 1) The process of diameter reduction and insertion is as follows:

[0038] First, use a diameter reduction machine 5 to reduce the diameter of the lining repair pipe 4 with an outer diameter larger than the inner diameter of the heat pipeline 1 to be repaired, so that it can be inserted into the heat pipeline 1 to be repaired. Then, under the traction of a traction and stretching machine 6, the diameter-reduced lining repair pipe 4 is pulled through the cleaned heat pipeline 1 to be repaired, keeping its inlet end and outlet end protruding from the ends of the heat pipeline 1 to be repaired respectively, thus completing the process of diameter reduction and insertion.

[0039] It should be noted that the diameter reduction method of the lining repair pipe 4 can adopt U-shaped hemming diameter reduction or O-shaped diameter reduction, and there is no limitation on this. U-shaped hemming diameter reduction means that the lining repair pipe 4 is radially bent, making one side of its circular cross-section concave inward to form a U shape, thereby changing the maximum span of its cross-section. O-shaped diameter reduction is another diameter reduction method that keeps the circular cross-section without depression but reduces the diameter.

[0040] 2) The process of hemming and fixing is as follows:

[0041] After the diameter-reduced lining repair pipe 4 is turned and hemmed at the inlet end, it is hermetically connected by hemming with the external flange connection head 2 at the same end through a fixed sealing end cover 3, so that the inlet end of the lining repair pipe 4 is kept airtight, thus completing the process of hemming and fixing.

[0042] It should be noted that the hemming method adopted for the inlet end of the lining repair pipe 4 can be fusion welding hemming or flange hemming, and there is no limitation on this. After hemming, a fixed sealing end cover 3 matching the outer diameter of the flange of the external flange connection head 2 can be selected. As Figure 3 shown, the hemmed section of the lining repair pipe 4 can be clamped between the external flange connection head 2 and the fixed sealing end cover 3, and then tightened with bolts, so as to ensure that the inlet end of the lining repair pipe 4 can be airtight.

[0043] 3) The process of pre-stretching is as follows:

[0044] With the inlet end of the lining repair pipe 4 fixed, use a traction and stretching machine 6 to stretch and extend the outlet end of the lining repair pipe 4, and the pre-stretching amount is the strain caused by the temperature difference between the working temperature and the ambient temperature of the lining repair pipe 4, thus completing the process of pre-stretching.

[0045] It should be noted that the above pre-stretching amount needs to be determined according to actual theoretical calculations. Since the thermal pipeline is often in a high-temperature state far higher than the ambient temperature during use, the originally flat lining pipeline at the ambient temperature will elongate due to thermal expansion and contraction, resulting in bulges and edges. Therefore, pre-stretching the lining repair pipeline 4 in advance can eliminate the strain caused by the temperature difference between the working temperature and the ambient temperature of the lining repair pipeline 4 in advance. As an implementation method of the embodiment of the present invention, during the pre-stretching process, the calculation formula for the pre-stretching amount Δl of the lining repair pipeline 4 is as follows: Δl = ΔTLσ, where ΔT is the temperature difference between the actual working temperature and the ambient temperature of the lining repair pipeline 4, L is the length of the lining repair pipeline 4 before stretching, and σ is the thermal strain of the lining repair pipeline 4.

[0046] 4) The process of inflating and expanding the pipe is as follows:

[0047] Use the air compressor 7 to inflate and expand the pre-stretched lining repair pipeline 4 through the air inlet hole 8 to restore the lining repair pipeline 4. After restoration, the lining repair pipeline 4 is in interference fit with the thermal pipeline 1 to be repaired, so that the outer wall of the lining repair pipeline 4 is closely attached to the inner wall surface of the thermal pipeline 1 to be repaired. After removing the traction stretching machine 6, the lining repair pipeline 4 cannot shrink and rebound, and the process of inflating and expanding the pipe is completed.

[0048] It should be noted that since the stretching of the lining repair pipeline 4 is realized by the traction stretching machine 6, but the traction force of the subsequent traction stretching machine 6 needs to be removed. Therefore, the lining repair pipeline 4 needs to rely on the friction force between itself and the thermal pipeline 1 to be repaired to maintain its pre-stretched state. In actual application, since the diameter of the lining repair pipeline 4 can basically return to the original diameter before pipe shrinking after the pipe is inflated and restored, the friction force between the lining repair pipeline 4 and the thermal pipeline 1 to be repaired after inflation and restoration can be controlled by selecting the diameter of the lining repair pipeline 4. As Figure 4 shown, the states before and after pipe expansion are shown when the lining repair pipeline 4 adopts U-shaped flanging and pipe shrinking. In the present invention, the outer diameter of the lining repair pipeline 4 after restoration and the inner diameter of the thermal pipeline 1 to be repaired meet the dimensional requirements of interference fit, and it should be ensured that the friction force between the inner wall of the thermal pipeline 1 to be repaired and the lining repair pipeline 4 in the interference fit state is greater than the stress shrinkage force of the lining repair pipeline 4. The specific diameter of the lining repair pipeline 4 can be optimized and determined according to the actual situation.

[0049] Generally speaking, the working pressure for the air compressor 7 to inflate and expand the lining repair pipeline 4 is 0.12 - 0.3 Mpa, so as to be able to restore the shrunk lining repair pipeline 4 back to its original diameter.

[0050] It should be noted that if the inner lining repair pipe 4 adopts a U-shaped flanging and diameter reduction, it must be expanded by a compressor 7 after insertion. However, if the inner lining repair pipe 4 adopts an O-shaped diameter reduction, since the pipe has no restraint, it may not be necessary to use a compressor 7 for expanding the pipe, and it can recover by itself. However, considering the expanding efficiency, even if the inner lining repair pipe 4 adopts an O-shaped diameter reduction, the pipe diameter can also be quickly restored by using expanding.

[0051] 5) The process of flanging connection is as follows:

[0052] Cut the excess part of the outlet end of the inner lining repair pipe 4 that extends out of the heat pipe 1 to be repaired, and only retain the flanging section for flanging fixation; fix the retained flanging section of the inner lining repair pipe 4 and the external flange connector 2 at the same end by flanging, and reconnect the two ends of the heat pipe 1 to be repaired with the inner lining repair pipe 4 to the heat pipe network through flanges again to complete the flanging connection process.

[0053] It should be noted that the flanging method adopted for the outlet end of the inner lining repair pipe 4 in this step can also be fusion welding flanging or flange flanging.

[0054] In addition, since a fixed sealing end cover 3 is installed at the inlet end of the inner lining repair pipe 4, the fixed sealing end cover 3 at the inlet end needs to be removed in advance before reconnecting the two ends of the heat pipe 1 to be repaired with the inner lining repair pipe 4 to the heat pipe network through flanges again.

[0055] To ensure the reliability of the repair of the present invention, after the heat pipe 1 to be repaired is reconnected to the heat pipe network, the repaired pipe needs to be pressure tested, and only after the pressure test is qualified can the previously excavated soil be backfilled, the operation pit be filled, and the ground above the pipe network be restored.

[0056] To further facilitate the understanding of the implementation process of the present invention in application, a preferred embodiment is used to show the specific working process of the above Figure 1 shown heat pipe inner lining repair process method based on temperature strain compensation, and its process is as follows:

[0057] Before repairing the heat pipeline, first identify the damaged location of the heat pipeline, determine the length of the pipeline to be repaired, excavate operation pits at both ends of the pipeline to be repaired, and conduct pipe cutting. Special external flange connectors 2 are welded to both ends of the pipe at the pipe cutting location, and the welding method should comply with the standard of GB / T 19809-2005 "Plastics pipes and fittings - Polyethylene (PE) pipes / pipes or pipes / fittings - Preparation of butt fusion assemblies" (ISO 11414:1996). After pipe cutting, internal inspection of the heat pipeline 1 to be repaired is carried out through a CCTV endoscope to determine the internal environment and the state to be repaired of the heat pipeline, and the heat pipeline 1 to be repaired is cleaned by means of ball brushes, steel brushes, piston brushes, etc.

[0058] Before the lined repair pipeline 4 is installed and connected to the heat pipeline 1 to be repaired, the lined pipeline is first subjected to diameter reduction treatment. After the lined repair pipeline 4 is reduced in diameter by a diameter reduction machine 5, it is pulled through the cleaned heat pipeline 1 to be repaired by a traction and stretching machine 6 to complete the diameter reduction and insertion process. When using a "U"-type diameter reduction and insertion lining, the diameter reduction amount of the pipeline is generally 25% - 30%, and the traction speed should be 3 - 5 m / min and shall not exceed 8 m / min; when using an "O"-type diameter reduction, the diameter reduction amount of the pipeline is generally 5% - 10%.

[0059] The lined repair pipeline 4 after diameter reduction is turned and folded at the inlet end. After being preliminarily fixed by flange connection with the external flange connector 2 welded to the end of the heat pipeline 1 to be repaired through a fixed sealing end cover 3, edge bending and sealing are carried out to complete the edge bending and fixing process.

[0060] The other end of the lined repair pipeline 4 is stretched under the action of a traction and stretching machine 6 to extend it by Δl to complete the pre-stretching process and sealing. Among them, Δl is the strain caused by the temperature difference between the working temperature and the ambient temperature of the lined repair pipeline 4, and the pre-stretching amount Δl of the lined repair pipeline 4 = ΔTLσ. In the formula, ΔT is the temperature difference between the actual working temperature and the ambient temperature of the pipeline, L is the length of the lined repair pipeline 4, and σ is the thermal strain of the lined repair pipeline 4.

[0061] After the pipeline pre-stretching is completed, the pre-stretched lined repair pipeline 4 is inflated and expanded through a compressor 7 via an air inlet hole 8. Generally, an air pressure of 1 - 2 Kg is selected for pressure testing and expansion operation. Under the action of the pressure, the lined repair pipeline 4 is restored to approximately the original inner and outer diameter dimensions of the pipeline before diameter reduction to complete the inflation and expansion process. Since the outer diameter of the lined repair pipeline 4 after restoration satisfies the interference fit dimension requirements with the inner diameter of the heat pipeline 1 to be repaired, the outer surface of the lined repair pipeline 4 after expansion fits closely with the inner wall surface of the heat pipeline 1 to be repaired, and under the action of the pipeline wall friction, it can prevent the lined repair pipeline 4 from shrinking and rebounding when there is no stretching effect.

[0062] After the inflation and expansion of the pipe are completed, determine the length of the folded edge of the lining repair pipe 4 according to the size of the external flange connector 2 welded to the end of the heat pipeline 1 to be repaired, and cut off the redundant lining pipe. After the other end of the lining repair pipe 4 is fixed by flanging with the external flange connector 2, the two ends of the heat pipeline 1 to be repaired are respectively connected to the unrepaired heat pipelines in the heat pipeline network through flanges to complete the flanging connection process. Then, pressure test the repaired pipeline. It is required that when the pressure is 1 MPa, the pressure drop within 6 hours does not exceed 1%. After the pressure test is qualified, fill the operation pit and restore the road surface.

[0063] The embodiments described above are only a preferred solution of the present invention, but it is not intended to limit the present invention. Those of ordinary skill in the relevant technical fields can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A thermal pipeline lining repair process method based on temperature strain compensation, characterized in that, The pipeline to be repaired (4), a pipe diameter reducing machine (5), a traction and stretching machine (6), and a compressor (7) are used to repair the heat pipeline to be repaired (1); wherein, external flange connectors (2) are welded to both ends of the heat pipeline to be repaired (1), and an air inlet hole (8) is provided at the outlet end of the pipeline for lining repair (4). The described lining repair process method includes five processes: pipe diameter reducing and inserting, edge bending and fixing, pre-stretching, inflating and expanding the pipe, and edge bending and connecting. The specific processes are as follows: First, use the pipe diameter reducing machine (5) to reduce the diameter of the pipeline for lining repair (4) whose outer diameter is larger than the inner diameter of the heat pipeline to be repaired (1) so that it can be inserted into the heat pipeline to be repaired (1). Then, under the traction of the traction and stretching machine (6), the reduced-diameter pipeline for lining repair (4) is passed through the cleaned heat pipeline to be repaired (1), keeping its inlet end and outlet end protruding from the ends of the heat pipeline to be repaired (1) respectively, thus completing the pipe diameter reducing and inserting process. After the diameter of the pipeline for lining repair (4) is reduced, it is turned and folded at the inlet end and then edge-bent and sealedly connected to the external flange connector (2) at the same end through a fixed sealing end cover (3), so that the inlet end of the pipeline for lining repair (4) is kept airtight, thus completing the edge bending and fixing process. With the inlet end of the pipeline for lining repair (4) fixed, use the traction and stretching machine (6) to stretch and extend the outlet end of the pipeline for lining repair (4), and the pre-stretching amount is the strain caused by the temperature difference between the working temperature and the ambient temperature of the pipeline for lining repair (4), thus completing the pre-stretching process. Use the compressor (7) to inflate and expand the pre-stretched pipeline for lining repair (4) through the air inlet hole (8) to realize the restoration of the pipeline for lining repair (4). After restoration, the lined pipeline and the heat pipeline are in interference fit, so that the outer wall of the pipeline for lining repair (4) is closely attached to the inner wall surface of the heat pipeline to be repaired (1). After removing the traction and stretching machine (6), the pipeline for lining repair (4) cannot shrink and rebound, thus completing the inflating and expanding the pipe process. Cut the excess part of the outlet end of the pipeline for lining repair (4) that protrudes from the heat pipeline to be repaired (1), and only retain the folded edge section for edge bending and fixing; fix the retained folded edge section of the pipeline for lining repair (4) to the external flange connector (2) at the same end by edge bending, and reconnect the two ends of the heat pipeline to be repaired (1) with the pipeline for lining repair (4) to the heat pipe network through flanges again, thus completing the edge bending and connecting process.

2. The method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 1, characterized in that During the described pre-stretching process, the pre-stretching amount Δl of the pipeline for lining repair (4) = ΔTLσ, where ΔT is the temperature difference between the actual working temperature and the ambient temperature of the pipeline for lining repair (4), L is the length of the pipeline for lining repair (4) before stretching, and σ is the thermal strain of the pipeline for lining repair (4).

3. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 1, characterized in that The outer diameter of the pipeline for lining repair (4) after restoration and the inner diameter of the heat pipeline to be repaired (1) meet the dimensional requirements of interference fit, and it should be ensured that the friction force between the inner wall of the heat pipeline to be repaired (1) and the pipeline for lining repair (4) under the interference fit state is greater than the stress shrinkage force of the pipeline for lining repair (4).

4. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 1, characterized in that, Before reconnecting the two ends of the damaged heat pipeline (1) with the lined repair pipeline (4) to the heat pipeline network through flanges, it is necessary to pre-remove the fixed sealing end cover (3) at the inlet end.

5. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 1, characterized in that, The diameter reduction methods of the lined repair pipeline (4) include U-shaped hemming diameter reduction and O-shaped diameter reduction.

6. A thermal pipeline lining repair process method based on temperature strain compensation according to claim 1, characterized in that, The hemming methods include fusion welding hemming and flange hemming.

7. A thermal pipeline lining repair process method based on temperature strain compensation according to claim 1, characterized in that, The working pressure for the compressor (7) to inflate and expand the lined repair pipeline (4) is 0.12 - 0.3 Mpa.

8. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 1, characterized in that, The damaged heat pipeline (1) to be repaired is obtained by excavating operation pits on both sides of the damaged position in the heat pipeline and performing pipe cutting.

9. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 8, characterized in that The external flange connector (2) is sleeved at the two pipe cutting positions by hot melt welding.

10. A method for repairing the inner lining of a thermal pipeline based on temperature strain compensation according to claim 8, characterized in that, After the damaged heat pipeline (1) is reconnected to the heat pipeline network, it is necessary to perform a pressure test on the repaired pipeline. After the pressure test is qualified, the operation pit is refilled.

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