Method for conveniently melting and taking out foreign matter in boiler header

Abstract

The invention relates to the technical field of boiler maintenance, and discloses a method for conveniently melting and taking out foreign matters in a boiler header, which comprises the following steps of: S1, monitoring wall temperature measuring point data of each communicating pipeline in a boiler operation process, and identifying a target pipe section with abnormal temperature rise; s2, three-stage admission control is carried out on the target pipe section after the furnace is shut down, and the three-stage admission control comprises working condition freezing and path pre-arrangement and is used for determining a main operation inlet and a standby inlet; and S3, determining a suspected foreign matter area of the target pipe section and selecting an operation inlet according to a minimum intrusion decision tree principle in combination with a ball passing test result and temperature distribution of the measuring points. Iron-shaped foreign matters with large volumes are melted by a melting gun in the header, the volume is reduced, and then the foreign matters are quickly taken out, and the foreign matters can be quickly cleaned without opening a hand hole cover of the header or disassembling a pipeline, so that the working hours of welding and post-welding heat treatment caused by disassembling the pipeline and cutting the hand hole cover of the header due to taking the foreign matters are saved, and the effect of shortening the repair time of a unit is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of boiler maintenance, in particular to a method for melting and removing foreign matter in a boiler header. BACKGROUND

[0002] The boiler header is a key component for distributing steam or water flow in the boiler, usually located in the water cooling wall system of the boiler. The header helps to guide steam or hot water to different parts of the boiler by connecting multiple pipes, ensuring the normal operation of the boiler. However, during long-term operation, due to water quality problems inside the boiler, deposits or external equipment aging, etc., foreign matter often accumulates in the boiler header. These foreign matters are usually iron filings, impurities or other solid substances, which may come from corrosion, wear and tear, welding residues of the boiler body, etc. If not cleaned in time, these foreign matters can block the flow path of the header, leading to reduced efficiency of the boiler or serious equipment failure.

[0003] Currently, for cleaning foreign matter in the boiler header, the common traditional method is to cut the header manhole cover or disassemble the pipe to enter the header interior for manual cleaning. However, during use, the boiler needs to be shut down for a long time, and manual disassembly, cleaning, and welding, heat treatment and slow cooling of the disassembled pipes are required, which consumes a lot of time and labor cost, significantly prolongs the shutdown time of the boiler, and affects the production efficiency of the entire power plant. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a method for melting and removing foreign matter in a boiler header, which solves the problem of consuming a large amount of time and labor cost during maintenance, significantly prolonging the shutdown time of the boiler, and affecting the production efficiency of the entire power plant.

[0005] To achieve the above purpose, the present application is implemented by the following technical scheme: a method for melting and removing foreign matter in a boiler header, comprising the following steps: S1: monitoring the wall temperature measurement point data of each communication pipe during the operation of the boiler, and identifying the target pipe section with abnormal temperature rise; S2: implementing three-stage access control on the target pipe section after shutdown, the three-stage access control including working condition freezing and path pre-arrangement, for determining the main operation entrance and the standby entrance; S3: determining the suspected foreign matter area of the target pipe section and selecting the operation entrance according to the principle of minimum invasion decision tree, combined with the results of the ball passing test and the temperature distribution of the measurement points; S4: detecting the target pipe section header outlet area by inserting an endoscope through the selected entrance, positioning the foreign matter position, and establishing a welding gun operation control parameter table to determine the insertion depth, nozzle angle and flame direction of the melting welding gun; S5: Perform the step of controlled melting by section according to the welding torch operation control parameter table; S6: After confirming that the foreign matter is movable, perform the step of taking out and perform the step of inspection.

[0006] Preferably, the step of freezing the working condition in S2 includes isolating the medium in the loop where the target pipe section is located to ensure the safety of the maintenance environment. The path pre-arrangement includes selecting a main operation entrance and a backup entrance, and determining the operability and visual range of the main operation entrance and the backup entrance.

[0007] Preferably, the step of minimum invasion decision tree in S3 includes: After the ball passing test, if the ball passing is successful, it is determined that the blockage position is near the outlet of the header; Combine the temperature data of the target pipe section and the ball passing test result to generate a suspected blockage area confidence map; According to the confidence map, select the main entrance for inspection. If the visual angle of the main entrance does not meet the requirements, enable the backup entrance.

[0008] Preferably, the welding torch operation control parameter table in the step S5 includes: Operation parameters of welding torch insertion depth, nozzle angle, flame direction, and retreat distance of grabbing device; All operations are performed in sequence to ensure that the melting direction of the welding torch is consistent with the size reduction direction of the foreign matter.

[0009] Preferably, in the step S5, the step of controlled melting by section includes: Peripheral thinning: use oxyacetylene flame to heat the contact area of the foreign matter in a ring shape to form a melting interface; Directional melting: adjust the flame angle to control the flow direction of the melted metal to the direction of the header outlet; Cooling: stop heating and cool the foreign matter.

[0010] Preferably, after the cooling step, perform an endoscopic round of verification. Observe the change in the projection of the foreign matter through the endoscope to determine whether the size of the melted foreign matter is smaller than the diameter of the pipe outlet. If the size of the melted foreign matter is still larger than the diameter of the pipe outlet, repeat the step of controlled melting by section and re-verify.

[0011] Preferably, when the endoscopic image shows that the melting direction deviates from the predetermined passage direction or that abnormal molten droplets are generated in the flame area, immediately stop the current operation for cooling observation. After cooling, observe the shape change of the melting area through the endoscope to confirm whether the size of the foreign matter is smaller than the diameter of the pipe outlet. If the size is smaller than the diameter of the pipe outlet, proceed to the step of taking out. If the size does not meet the requirements, adjust the insertion depth, nozzle angle, and flame direction of the welding torch according to the entrance and attitude linkage control table, and continue to perform the step of controlled melting by section.

[0012] Preferably, in the S6 step, the inspection includes confirming no residual fragments by reverse scanning with the endoscope after foreign matter removal, and verifying by ball passing and temperature measurement re-measurement, and then archiving the endoscope image, entry and posture linkage control table to form a closed loop report.

[0013] Preferably, when the main entry cannot achieve the expected observation or operation condition, an entry switching step is performed, which is only to change the main operation entry operation to the backup entry operation.

[0014] Preferably, in the segmented controlled melting step, a straight bar type oxyacetylene suction type melting welding gun is used for annular heating of the foreign matter contact area, and a four-jaw foreign matter grabbing device movable forward and backward is arranged on the welding gun.

[0015] The present application provides a method for conveniently melting and removing foreign matter in a boiler header.

[0016] 1. The present application quickly removes the foreign matter after reducing the volume by melting the large volume iron-like foreign matter in the header with a melting gun, and quickly removes the foreign matter without opening the hand hole cover or disassembling the pipeline, thereby saving the welding and post-welding heat treatment time caused by disassembling the pipeline and opening the header hand hole cover, and shortening the unit repair time.

[0017] 2. The present application uses segmented controlled melting to locally heat the foreign matter with an oxyacetylene flame, effectively reduces the volume of the foreign matter within a controlled range, and ensures that the foreign matter can pass through the pipeline outlet, thereby improving the efficiency of foreign matter removal.

[0018] 3. The present application pre-arranges the path, permits the risk, and selects multiple entries to enhance the flexibility of operation on the basis of ensuring the safety of the operation path, and combines real-time temperature monitoring and cooling verification to timely adjust the operation strategy, thereby avoiding damage to the header wall or safety accidents caused by improper operation, and significantly improving the safety and reliability of the operation.

[0019] 4. The present application precisely positions the foreign matter by endoscope and performs round verification after each melting round, thereby ensuring the accuracy of the melting process. When the endoscope image shows that the size of the foreign matter does not meet the requirements, the melting step is continued by adjusting the insertion depth, nozzle angle and flame direction of the welding gun, thereby ensuring that each operation achieves the expected effect. The volume of the foreign matter after melting meets the standard of the pipeline outlet, thereby avoiding the situation of missing or excessive melting, and improving the success rate and safety of the operation. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The method flowchart of the present application. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] Please refer to the drawings of the present application Figure 1 The embodiment of the present application provides a method for melting and removing foreign matter in a boiler header, comprising the following steps: S1: monitoring the wall temperature measurement point data of each communication pipeline during the operation of the boiler, and identifying the target pipe section with abnormal temperature rise; S2: implementing three-stage access control on the target pipe section after shutdown, which includes working condition freezing and path pre-arrangement, and is used to determine the main operation entrance and the standby entrance; S3: according to the principle of minimum invasion decision tree, combining the results of the ball passing test and the temperature distribution of the measurement points, determining the suspected foreign matter area of the target pipe section and selecting the operation entrance; S4: inserting an endoscope through the selected entrance to detect the header outlet area of the target pipe section, positioning the foreign matter position, and establishing a welding gun operation control parameter table to determine the insertion depth, nozzle angle and flame direction of the melting welding gun; S5: executing the step of segment controlled melting according to the welding gun operation control parameter table; S6: after confirming that the foreign matter is movable, implementing the removal operation and checking.

[0023] By adopting the above technical solution, in S1, during the operation of the boiler, the wall temperature measurement point data of each communication pipeline is monitored in real time, so that the target pipe section with abnormal temperature can be found in time. Because temperature anomaly usually reflects the foreign matter or blockage problem in the pipeline, the problem pipe section can be accurately located through temperature data analysis, thereby providing a target area for subsequent operation; In S2, after confirming that the target pipe section has an abnormality, the boiler is stopped and three-stage access control is performed: working condition freezing, path pre-arrangement and risk permission, which effectively ensures the safety and controllability of the operation.

[0024] In S3, according to the principle of minimum invasion decision tree, combining the results of the ball passing test and the temperature data of the target pipe section, the position and nature of the foreign matter can be accurately judged, and by generating a confidence map of the suspected blockage area, the most suitable entrance can be selected from multiple paths for subsequent endoscopic detection and operation, unnecessary cutting operation is reduced, and the efficiency and safety of the operation are improved; In S4, the endoscope is inserted through the selected access port to accurately locate the position of the foreign object, and a welding gun operation control parameter table is established. The table contains key parameters such as the insertion depth of the welding gun, the nozzle angle, and the flame direction, which can ensure that the welding gun is always aligned with the foreign object during the melting process, and the direction of the flame is consistent with the shrinkage direction of the foreign object, thereby effectively avoiding problems such as molten droplet splashing that may occur during the melting process;

[0025] In S5, the step of controlled segmental melting is performed according to the welding gun operation control parameter table. Through segmental melting, the foreign object is locally heated to an appropriate temperature and cooled to reduce its volume, ensuring that the melted foreign object can be removed through the pipe outlet. Segmental controlled melting gradually eliminates the blockage of the foreign object, reducing thermal damage and improving the reliability of removal;

[0026] In S6, after confirming that the foreign object can be removed, the foreign object is removed using a grabbing device. After removal, an inspection is performed to ensure that the removed foreign object does not affect the normal use of the pipe, and a through-ball verification and temperature measurement are further performed to confirm the status of the target pipe section. Through this operation, it can be ensured that not only the cleaning work is completed, but also the subsequent use of the pipe is not affected.

[0027] Compared with the traditional method of disassembling the pipe or cutting the handhole cover of the header to clean the foreign object, the above steps melt the foreign object in the header and reduce its volume, so that it is no longer necessary to disassemble the pipe or cut the handhole cover, thereby reducing a large amount of welding and heat treatment work, and reducing the maintenance time caused by removing the foreign object, significantly improving the efficiency in the process of boiler equipment repair.

[0028] The working condition freezing in S2 includes isolating the medium of the loop where the target pipe section is located to ensure the safety of the maintenance environment; Path pre-arrangement includes selecting a main operation access port and a backup access port, and determining the operability and visual range of the main operation access port and the backup access port.

[0029] By adopting the above technical scheme, the working condition freezing isolates the medium of the loop where the target pipe section is located, effectively preventing the operation risk caused by the flow of high-temperature medium, and ensuring that the subsequent maintenance work of the operator is carried out in a safe environment. By isolating the medium, the safety hazard caused by the leakage of high-temperature medium can be avoided, and the entire operation process can be ensured not to be disturbed by unexpected factors;

[0030] In terms of path pre-arrangement, the main operation access port and the backup access port are selected, and the operability and visual range of the two are verified to ensure that the path can be flexibly adjusted according to the actual situation during the operation process, avoiding unnecessary obstacles caused by the access port during the operation process. By determining the operable path and the visual range in advance, the decision uncertainty during the on-site operation can be effectively reduced; Through the working condition freezing and path pre-arrangement, it is ensured that the subsequent foreign matter cleaning process can be carried out in safe and controllable conditions, and ideal operation conditions are provided for the welding gun operation and melting work.

[0031] The minimum invasion decision tree in the S3 step includes: After the ball passing test, if the ball passing is passed, it is determined that the blockage position is located near the header outlet. Combined with the target pipe section temperature data and the ball passing test result, a suspected blockage area confidence map is generated. According to the confidence map, the main entrance is selected for inspection, and if the main entrance visual angle does not meet the requirements, the standby entrance is enabled.

[0032] By using the above technical scheme, the position of the foreign matter is determined and the appropriate entrance is selected by using the minimum invasion decision tree, which can effectively optimize the operation path and reduce unnecessary cutting or entrance adjustment. After the ball passing test, if the ball passing is passed, it indicates that the channel of the target pipe section is relatively smooth, and it can be determined that the blockage is located near the header outlet, thereby avoiding unnecessary further inspection of the entire pipe system. Combined with the temperature data of the target pipe section and the ball passing test result, a suspected blockage area confidence map is generated to identify the area where the foreign matter may exist, and the main entrance is selected for further operation, thereby ensuring that the operation process is more accurate, reducing the selection of incorrect paths, and improving the operation efficiency. If the visual angle of the main entrance does not meet the requirements, the system automatically enables the standby entrance to ensure the flexibility and smooth operation of the operation. Therefore, not only the accuracy of path selection is improved, but also the additional work and risks caused by improper operation path are effectively avoided, thereby enhancing the safety and efficiency of the operation.

[0033] The welding gun operation control parameter table in the S5 step includes: The operation parameters of the welding gun insertion depth, nozzle angle, flame direction and grabbing device retreat distance; All operations are executed in sequence to ensure that the melting direction of the welding gun is consistent with the foreign matter reduction direction.

[0034] By adopting the above technical solution, the welding torch insertion depth, nozzle angle, flame direction and retreat distance of the grabbing device are controlled to operate the welding torch, ensuring that the melting process is carried out in the set direction and target, thereby effectively reducing the droplet splashing and irregular melting. By performing each operation according to the welding torch operation control parameter table, it can be ensured that the insertion depth of the welding torch matches the position of the foreign matter, and the nozzle angle and the flame direction are always aligned with the melting area, thereby improving the melting efficiency and control accuracy. At the same time, the retreat distance control of the grabbing device ensures that the welding torch is not disturbed during the melting process, avoiding unnecessary contact with the melted area, and further ensuring the stability and controllability of the melting process. The consistency of the melting direction of the welding torch and the reduction direction of the foreign matter is realized, and the volume change of the melted foreign matter is ensured to meet the expectation, thereby smoothly completing the removal of the foreign matter.

[0035] In the S5 step, the segmented controlled melting step includes: Peripheral thinning: using oxyacetylene flame to perform annular heating on the foreign matter contact area to form a melting interface; Directional melting: adjusting the flame angle to control the flow direction of the melted metal to the outlet direction of the header; Cooling: stopping heating and cooling the foreign matter.

[0036] By adopting the above technical solution, the peripheral thinning, directional melting and cooling three-stage operation mode is adopted to ensure that the melting process reduces the volume of the foreign matter to the standard that can be removed. First, the peripheral thinning performs annular heating on the foreign matter contact area by oxyacetylene flame to form a melting interface, gradually thins the edge of the foreign matter, thereby reducing the heat affected zone of the melting area and avoiding excessive heating of the header wall or pipeline. Then, in the directional melting stage, by adjusting the flame angle, the flow direction of the melted metal is controlled to flow along the outlet direction of the header, ensuring that the melted metal moves towards the outlet direction of the pipeline, thereby improving the removability of the foreign matter. When entering the cooling stage, by stopping heating and cooling the foreign matter, it is ensured that the volume of the foreign matter is reduced, and it is checked whether the melting area meets the removal requirement. After cooling, it is confirmed that the foreign matter has reached the predetermined size requirement, ensuring the smooth completion of the removal operation and avoiding the risk of excessive melting caused by re-heating.

[0037] The segmented controlled melting step can avoid excessive melting and uneven heating, thereby ensuring that the volume of the melted foreign matter can smoothly pass through the pipeline outlet, ensuring the efficiency and safety of the operation.

[0038] After the cooling step, an endoscope round verification is performed, which judges whether the size of the melted foreign matter is smaller than the diameter of the pipeline outlet by observing the change of the foreign matter projection through the endoscope. If the size of the melted foreign matter is still larger than the diameter of the pipeline outlet, the segmented controlled melting step is repeated and re-verified.

[0039] By adopting the above technical scheme, after the cooling step, the endoscopic round verification is performed to ensure that the size of the melted foreign matter reaches the standard that can pass through the pipeline outlet. If the size of the melted foreign matter is still greater than the diameter of the pipeline outlet, the segmented controlled melting step needs to be repeated and the size verification needs to be performed again, the volume change of the foreign matter after each round of melting is controlled, the melting process is continuously and effectively ensured, and unnecessary loss or incomplete melting of the foreign matter caused by excessive melting is avoided;

[0040] The endoscopic round verification is used to determine whether the foreign matter has been sufficiently melted to a suitable size, while avoiding overheating or damage caused by repeated heating, and ensuring that the size after each cooling meets the removal standard. If the size of the foreign matter does not meet the size requirement, the melting and verification operations are repeated in time, thereby maximizing the size of the foreign matter before final removal and ensuring the smooth progress of the operation.

[0041] When the endoscopic image shows that the melting direction deviates from the predetermined channel direction or abnormal molten droplets are generated in the flame area, the current operation is immediately suspended for cooling observation. After cooling, the shape change of the melting area is observed through the endoscope to confirm whether the size of the foreign matter is smaller than the diameter of the pipeline outlet. If the size is smaller than the diameter of the pipeline outlet, the removal operation is entered. If the size does not meet the requirement, the insertion depth, nozzle angle and flame direction of the welding torch are adjusted according to the entry and attitude linkage control table, and the segmented controlled melting step is continued.

[0042] By adopting the above technical scheme, through real-time monitoring and operation adjustment, the melting process is always ensured to be in a controlled state, avoiding excessive melting or uneven melting area caused by deviation of the flame direction or abnormal molten droplets, thereby affecting the removal effect. The cooling observation can effectively verify the melting result, avoid excessive heating or insufficient melting, and ensure that the foreign matter meets the appropriate size requirement. Through this control method, the volume change of the foreign matter after each round of melting meets the expectation, ensuring the success rate of removal and the safety of the operation.

[0043] In the S6 step, the inspection includes reverse scanning through the endoscope after the foreign matter is removed to confirm that there is no residual debris, and verification and re-measurement through the ball verification and temperature measurement are performed for review. Then, the endoscopic image, the entry and attitude linkage control table are archived to form a closed-loop report.

[0044] By adopting the above technical scheme, when checking, first, the endoscope is used to reverse scanning to confirm that there is no residual fragment in the pipeline after the foreign matter is removed, so as to ensure that no residual material is generated in the foreign matter removal process, and secondary blockage or other potential pipeline problems caused by residual fragments are avoided; the ball verification ensures that the flow path in the pipeline is unobstructed, confirms that no new blockage point is generated due to the removal of foreign matter in the operation process, and the temperature re-measurement ensures that the temperature in the pipeline has returned to the normal working range, so as to ensure that the system is in a safe operation state, finally, the endoscope image, the entry and attitude linkage control table and other operation records are archived to form a closed loop report, which provides complete operation records for subsequent inspection and verification, ensures the transparency and traceability of the whole process, meets the compliance requirements of equipment maintenance and overhaul, so as to ensure the integrity and safety of the foreign matter removal operation, and provides strong guarantee for the subsequent use of the equipment, and avoids potential problems caused by operation errors or missed inspection.

[0045] When the main entrance cannot reach the expected observation or operation condition, the entrance switching step is performed, and the entrance switching step is only to change the main operation entrance operation to the standby entrance operation.

[0046] By adopting the above technical scheme, by switching the main operation entrance to the standby entrance, it is ensured that when the main entrance cannot be effectively operated due to unsuitable viewing angle or space limitation, the foreign matter cleaning work can still be continued. Through this operation, the system can flexibly adjust the entrance path according to the on-site situation during actual operation, so as to avoid interruption of the whole operation due to unavailability of the main entrance. Thus, the flexibility of operation is enhanced, the continuity and efficiency of the operation are ensured, and the additional working hours or safety risks caused by the unavailability of operation are reduced.

[0047] In the step of controlled melting in sections, the oxygen-acetylene flame is used to heat the annular contact area of the foreign matter, and a straight strip type oxygen-acetylene suction type melting welding gun is used, and the welding gun is provided with a four-jaw foreign matter grabbing device which can move forward and backward.

[0048] By adopting the technical scheme, in the sectional controlled melting step, a straight strip oxyacetylene absorption type melting welding gun is adopted, the welding gun is provided with a four-jaw foreign matter grabbing device capable of moving forward and backward, the edge of the foreign matter is gradually heated in a ring heating mode to form a melting interface, so that the header wall or the pipeline is avoided from being excessively heated, and by controlling the heating range and the heating intensity, the size of the heat affected zone is effectively controlled. The adjustable parameters of the welding gun further ensure that the molten metal can flow towards the header outlet direction, avoiding unnecessary waste or misoperation in the melting process. The four-jaw foreign matter grabbing device can accurately grab the molten foreign matter and work cooperatively when the welding gun moves forward and backward, ensuring that the foreign matter is not excessively disturbed in the melting process, and finally ensuring that the foreign matter can be smoothly taken out through the pipeline outlet. Thus, the volume can be accurately reduced and smoothly removed, the safety and controllability of the operation are improved, and unnecessary loss in the melting process is reduced.

[0049] Embodiment Background: A certain boiler is a supercritical pressure variable pressure operation spiral pipe surrounding boiler, single furnace tower type arrangement, secondary reheat, four corner tangent circle combustion, balanced ventilation, solid state slagging, full steel suspension structure, island type open air arrangement, the furnace width is 17710mm, the furnace depth is 17710mm, the water wall lower header elevation is 7.5m, the furnace top pipe center elevation is 96.6m, and the large plate beam top elevation is 105.1m. The furnace is composed of a pipe membrane wall, and the water wall adopts a spiral pipe plus vertical pipe arrangement.

[0050] First, monitor the wall temperature measurement point data of each communication pipeline of the high-temperature final-stage superheater outlet header during the operation of the boiler, and find that the temperature of the 6th piece of pipe wall of the 25th row reaches 640℃, which is 40℃ higher than the normal operation temperature, and the pipe section is identified as a target pipe section with abnormal temperature rise; Then, after shutdown, the three-stage access control determines the main and standby inlets, and after shutdown, the target pipe section is subjected to three-stage access control, wherein the working condition freezing is to isolate the medium of the loop where the target pipe section is located, the path pre-discharge is to select the short pipe connected with the header of the 5th piece of pipe of the 25th row as the main operation inlet, the short pipe connected with the header of the 7th piece of pipe of the 25th row as the standby inlet, and determine the operability and visual range of the main operation inlet and the standby inlet. When the main inlet cannot reach the expected observation or operation condition, the inlet switching step is executed, which only changes the operation from the main operation inlet to the standby inlet; Then, according to the minimum invasion decision tree, the suspected foreign object area and the operation entrance are determined. According to the principle of minimum invasion decision tree, combined with the results of the pigging test and the temperature distribution of the measuring points, the pigging test is carried out on the target pipe section. After the pigging passes, it is determined that the blockage position is located near the outlet of the header. Combined with the temperature data of the target pipe section and the results of the pigging test, the suspected blockage area is determined, and it is determined that the foreign object is most likely located at the 25th row and the 6th piece of the pipe outlet in the header. The inspection of the main operation entrance can cover the suspected foreign object area, and the main operation entrance is selected as the operation entrance. Subsequently, the foreign object is located by endoscopy and a welding gun operation control parameter table is established. The endoscope is inserted through the selected operation entrance to detect the outlet area of the header of the target pipe section. It is located that there is an irregular iron sheet foreign object with a size of 50x40mm at the 25th row and the 6th piece of the pipe outlet in the header. The welding gun operation control parameter table is established to determine the insertion depth, nozzle angle and flame direction of the melting welding gun. The melting welding gun adopts an 800mm long straight strip type oxyacetylene jet suction type melting welding gun, and a four-jaw foreign object grabbing device fixed on the welding gun can move forward and backward. The welding gun operation control parameter table includes a welding gun insertion depth of 750mm, a gun mouth distance of 50mm from the surface of the foreign object, a nozzle angle of 45° with the surface of the foreign object, a flame direction towards the center area of the foreign object, and a grabbing device retreat distance of 50mm. All operations are executed in sequence to ensure that the melting direction of the welding gun is consistent with the shrinking direction of the foreign object. After that, the segmented controlled melting step is executed according to the welding gun operation control parameter table. The segmented controlled melting step includes peripheral thinning, directional melting and cooling. Peripheral thinning is to adjust the oxyacetylene flame after adjusting to the oxidizing flame to form a melting interface by annular heating of the foreign object contact area. Directional melting is to adjust the flame angle to control the melting metal flow to the outlet direction of the header. Cooling is to stop heating and cool the foreign object. After cooling, the endoscope is used to observe the change of the foreign object projection to determine whether the size of the melted foreign object is smaller than the diameter of the pipe outlet. If the size of the melted foreign object is still larger than the diameter of the pipe outlet, the segmented controlled melting step is repeated and verified again. If the melting direction deviates from the predetermined channel direction or abnormal molten droplets are generated in the flame area during the melting process, the current operation is immediately stopped for cooling observation. After cooling, the endoscope is used to observe the shape change of the melting area to confirm whether the size of the foreign object is smaller than the diameter of the pipe outlet. If the size is smaller than the diameter of the pipe outlet, the foreign object is removed. If the size does not meet the requirements, the insertion depth, nozzle angle and flame direction of the welding gun are adjusted according to the welding gun operation control parameter table, and the segmented controlled melting step is continued. Finally, the foreign object is removed and inspected. After confirming that the foreign object can be moved, the removal operation is carried out. After the removal operation is completed, the inspection is carried out. The inspection includes reverse scanning by endoscopy to confirm that there is no residual debris after the foreign object is removed, and verification by pigging and temperature measurement is carried out. Then, the endoscopic image and the welding gun operation control parameter table are archived to form a closed loop report.

[0051] Comparative Example Cut off header manhole cover to remove foreign matter, including cutting, groove making, preheating, welding, post-weld heat treatment, slow cooling.

[0052] Compared with the comparative examples, the construction period will be shortened to about 5 hours, greatly improving the overall work efficiency.

[0053] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for easily melting and removing foreign objects from a boiler header, characterized in that, Includes the following steps: S1: Monitor the wall temperature measurement data of each connected pipe during boiler operation to identify the target pipe section with abnormal temperature rise; S2: After the furnace is shut down, a three-stage access control is implemented on the target tube section. The three-stage access control includes operating condition freezing and path pre-arrangement, which are used to determine the main operation entrance and the backup entrance. S3: Based on the principle of minimum intrusion decision tree, combined with the results of the ball-passing test and the temperature distribution of the measuring points, determine the suspected foreign object area of ​​the target pipe section and select the operation entry point; S4: Insert an endoscope through the selected inlet to inspect the outlet area of ​​the header of the target pipe section, locate the foreign object, and establish a welding torch operation control parameter table to determine the insertion depth, nozzle angle and flame direction of the fusion welding torch; S5: Execute the segmented controlled melting step according to the welding torch operation control parameter table; S6: After confirming that the foreign object is movable, perform the removal operation and conduct an inspection.

2. The method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, The operating condition freeze in step S2 includes isolating the medium in the circuit where the target pipe section is located to ensure a safe maintenance environment. The path pre-arrangement includes selecting a primary operation entry point and a backup entry point, and determining the operability and visibility range of the primary operation entry point and the backup entry point.

3. The method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, The minimum intrusion decision tree in step S3 includes: If the ball passes through after the ball test, the blockage is determined to be near the header outlet. By combining the target pipe section temperature data and the results of the ball-passing test, a confidence map of the suspected blockage area is generated; Select the main entrance for inspection based on the confidence graph. If the main entrance view does not meet the requirements, then activate the backup entrance.

4. The method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, The welding torch operation control parameter table in step S5 includes: Operating parameters for welding torch insertion depth, nozzle angle, flame direction, and gripping device retraction distance; Perform all operations in sequence, ensuring that the melting direction of the welding torch is consistent with the shrinking direction of the foreign object.

5. The method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, In step S5, the segmented controlled melting step includes: Peripheral thinning: The contact area of ​​the foreign object is heated in a ring by an oxyacetylene flame to form a molten interface; Directional melting: Adjust the flame angle to control the flow of molten metal toward the header outlet; Cooling: Stop heating and cool the foreign object.

6. A method for easily melting and removing foreign objects from a boiler header according to claim 5, characterized in that, After the cooling step, an endoscopic round verification is performed. The change in the foreign object projection is observed through the endoscope to determine whether the size of the melted foreign object is smaller than the diameter of the pipe outlet. If the size of the melted foreign object is still larger than the diameter of the pipe outlet, the segmented controlled melting step is repeated and the verification is performed again.

7. A method for easily melting and removing foreign objects from a boiler header according to claim 6, characterized in that, When the endoscopic image shows that the melting direction deviates from the predetermined channel direction or abnormal molten droplets are generated in the flame zone, the current operation should be stopped immediately for cooling and observation. After cooling, the morphological changes of the melting zone should be observed through the endoscope to confirm whether the size of the foreign object is smaller than the diameter of the pipe outlet. If the size is smaller than the diameter of the pipe outlet, the removal operation should be performed. If the size does not meet the requirements, the insertion depth of the welding torch, the nozzle angle and the flame direction should be adjusted according to the inlet and attitude linkage control table, and the segmented controlled melting steps should continue to be executed.

8. A method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, In step S6, the inspection includes a reverse endoscopic scan after the foreign object is removed to confirm that there are no residual fragments, and a verification through ball-passing and temperature retesting. After that, the endoscopic image, entrance and posture linkage control table are archived to form a closed-loop report.

9. A method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, When the main entry point cannot meet the expected observation or operation conditions, an entry point switching step is performed. The entry point switching step simply changes the operation of the main operation entry point to the backup entry point operation.

10. A method for easily melting and removing foreign objects from a boiler header according to claim 1, characterized in that, In the segmented controlled melting step, the contact area of ​​the foreign object is heated in a ring by using an oxyacetylene flame. A straight-bar oxyacetylene injection welding torch is used, and the torch is equipped with a four-claw foreign object gripping device that can move back and forth.

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