A method for the mechanical cleaning of a subsea pipeline by rotating gas flow

Abstract

A kind of seabed pipeline rotating airflow mechanical descaling construction method, comprising: S1, field survey, the structure of pipeline and pipeline scale phenomenon are investigated, the placement position and connection mode of descaling equipment are determined;S2, pipeline replacement;S3, pipeline internal exploration;S4, equipment and pipeline are connected, cyclone generator, relevant auxiliary materials and recovery device are arranged, equipment is connected with the head and tail of pipeline, equipment is tested and pressure test leak point is detected;S5, pipeline descaling, according to the evaluation pipeline scale state of aeration, add abrasive, after preliminary purging pipeline is carried out 5-10 cycles, pipeline depth descaling and pipeline depth derusting 20-30 cycles are carried out, after the above cycle, pipeline is washed, purified and dried;S6, descaling effect check;S7, process recovery.The beneficial effects of the present application are to carry out descaling operation on the already scaled sea pipe, improve the pipeline conveying efficiency, improve the passability of the internal detector, avoid under-scale corrosion, and reduce the cost of seabed pipeline later operation and maintenance.

Description

Technical Field

[0001] This invention relates to the field of marine oil equipment technology, and more specifically to a method for mechanical descaling of subsea pipelines using rotating airflow. Background Technology

[0002] Among existing marine oil equipment technologies, the safe operation of subsea pipelines is crucial to the normal production of offshore oil and gas fields.

[0003] Currently, subsea pipelines frequently encounter scaling during operation. As scaling progresses, it reduces pipeline transport capacity, affecting the normal delivery of crude oil and production water. Severe scaling also reduces the permeability of internal detectors, increasing the risk of sensor jamming. Under-scale corrosion leads to localized corrosion within the pipeline, seriously impacting its safe operation.

[0004] Currently, there are two main types of methods for descaling subsea pipelines:

[0005] 1. Descaling with a pipeline cleaning tool: The cleaning tool is propelled by liquid and moves inside the pipeline. The scale is removed by the friction between the cleaning tool and the pipeline wall.

[0006] 2. Chemical descaling involves continuously adding chemical agents to the transported liquid, causing the scale inside the pipe to dissolve and detach. For pigging descaling, it is effective at removing scale with low hardness, but ineffective at removing high-hardness scale. The effectiveness of chemical descaling is closely related to the composition of the scale, and there is a potential risk of poor compatibility with the components of the transported medium, which may affect downstream processes. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a method for determining the execution of downhole hydraulic control sliding sleeve opening adjustment actions.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for mechanical descaling of subsea pipelines using rotating airflow includes:

[0010] S1. On-site survey: Investigate the structure and scaling phenomenon of the pipeline, determine the placement and connection method of the descaling equipment, and determine the overall construction plan.

[0011] S2, pipeline replacement;

[0012] S3. Pipeline inspection;

[0013] S4. Connect the equipment and pipelines, install the cyclone generator, related auxiliary materials and recovery devices, connect the equipment to the pipeline end, and test the equipment for leaks.

[0014] S5. Pipeline descaling: Based on the ventilation assessment of the pipeline scaling status, abrasive is added. After the initial purging of the pipeline and the pipeline descaling and rust removal work are carried out in sequence, the descaling effect in S6 is checked. Based on the inspection data of S6, the pipeline deep descaling and rust removal are carried out for 20 to 30 cycles. After the above cycles are completed, the pipeline is washed with water, purified and air-dried.

[0015] S6. Descaling effect check;

[0016] S7. Process restoration.

[0017] Pipeline structure includes the pipeline's direction, elevation difference, diameter changes, and bend locations.

[0018] The pipeline replacement in step S2 specifically includes:

[0019] S21. Replace the subsea water in the target pipeline;

[0020] S22. Replace the nitrogen in the target pipeline;

[0021] S23. Perform gas detection inside the target pipeline;

[0022] S24. Replace and remove the valves at both ends of the target pipeline.

[0023] In step S3, an image acquisition device is deployed to capture and screenshot image data, and the acquired data is used to analyze the corrosion and blockage situation.

[0024] In step S4, the cyclone generator includes multiple air compressors, an energy storage device, and a cyclone excitation system. During setup, the multiple air compressors at the beginning are connected to multiple energy storage devices via high-pressure hoses. The energy storage devices are connected in series via high-pressure hoses and then connected to the air inlet of the cyclone excitation system. The starting battery of one air compressor is connected to the control power supply of the cyclone excitation system. After the pipeline exploration in step S3 is completed, the air outlet of the cyclone excitation system is connected to the beginning of the target pipeline via a wear-resistant high-pressure hose. The end of the target pipeline is connected to the recovery device via a wear-resistant high-pressure hose.

[0025] The specific steps of step S4 include:

[0026] S41. After the safety supervisor confirms that the site meets the conditions for safe production, the air compressors are started in sequence to supply air to the energy storage device.

[0027] S42. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine-tuning valve of the vortex excitation system to 1 / 4, and after gas is introduced into the target pipeline, open the fine-tuning valve of the vortex excitation system to 1 / 2.

[0028] S43. When the pressure inside the pipe reaches 0.3 MPa, close the fine-tuning valve, maintain the pressure, and check for any leaks in the hoses and connecting flanges.

[0029] S44. When the air source pressure reaches 0.6MPa, immediately shut down the air compressor, check and confirm that there are no leaks in the hoses and connecting flanges, and open the release valve of the end recovery system.

[0030] S45. When the end-of-pipe recovery system release valve is opened to 1 / 4, open the main control valve and observe the rate of drop of the pipeline pressure gauge pointer to make a preliminary judgment on the diameter reduction of the middle section of the target pipeline.

[0031] S46. When the gas source pressure drops to 0.4MPa, close the fine-tuning valve and the main control valve.

[0032] The specific steps for the initial purging of the pipeline in step S5 include:

[0033] S511. Perform internal wall purging, and start the air compressors in sequence to supply air to the energy storage device;

[0034] S512. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 and supply gas into the target pipeline. Then adjust the opening of the fine adjustment valve to 1 / 2.

[0035] S513. When the pipe pressure reaches 0.3 MPa, close the fine-tuning valve;

[0036] S514. When the air source pressure reaches 0.6MPa, immediately shut down the air compressor, open the release valve, open the fine adjustment valve to 1 / 4, open the main control valve, and continue to input compressed air into the target pipeline to carry out a purging operation.

[0037] S515. When the gas source pressure drops to 0.4MPa, close the fine-tuning valve and the main control valve, record the operation time from opening the release valve to closing the main control valve, and then close the release valve.

[0038] S516. Repeat the above steps, gradually increasing the operating pressure to 0.8MPa until the loose scale and deposited water on the inner wall surface are completely removed.

[0039] The specific steps for descaling and derusting in step S5 include:

[0040] S521. Trial feeding is carried out on the target pipeline. After observation and judgment at the tail end, the amount of material input is gradually increased.

[0041] S522. After filling the storage tank and water tank in advance, start the air compressor in sequence to supply air to the energy storage device, open the feeding valve, and introduce 20Kg of abrasive and 20L of water into each metering tank once, and then close the two feeding valves.

[0042] S523. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 to supply gas into the target pipeline, and then adjust the fine adjustment valve to 1 / 2.

[0043] S524. When the pipe pressure reaches 0.3 MPa, close the fine-tuning valve;

[0044] S525. When the air source pressure reaches 0.6MPa, shut down the air compressor and open the relief valve;

[0045] S526. Sequentially open the feed valve, pressure valve, differential pressure adjustment valve and main control valve, control the airflow rotation speed at 12m / s, and perform trial cleaning of the rust and scale on the inner wall of the target pipeline.

[0046] S527. When the air source pressure drops to 0.4MPa, close the pressure valve, discharge valve, differential pressure adjustment fine-tuning valve, and main control valve in sequence, and then close the release valve to complete one internal wall test cleaning. Record the time it takes for the abrasive to reach the tail end, compare the time it takes for the abrasive to reach the tail end with the time recorded when the pipeline is purged, and analyze and judge the blockage status of the middle section of the target pipeline.

[0047] S528. When the time it takes for the abrasive to reach the end of the pipeline differs from the time recorded during pipeline purging by half, or when the abrasive does not reach the end of the pipeline, no more abrasive is added. The water volume is gradually increased to continue cleaning until the time it takes for the abrasive to reach the end of the pipeline and the time recorded during pipeline purging are within the difference range, and then a deep cleaning process is carried out.

[0048] The specific steps for deep descaling and rust removal in step S5 include:

[0049] S531. Start the air compressor in sequence to supply air to the energy storage device. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 to supply air to the target pipeline. Then adjust the fine adjustment valve to 1 / 2. When the pipeline pressure reaches 0.3MPa, close the fine adjustment valve.

[0050] S532. Open the abrasive and coolant feeding valves respectively, and introduce 40Kg of abrasive and 40L of water into their respective metering tanks once, then close both feeding valves.

[0051] S533. When the air source pressure reaches 0.6MPa, turn off the air compressor, open the release valve, and sequentially open the discharge valve, pressure valve, differential pressure adjustment fine-tuning valve and main control valve to control the airflow rotation speed at 36m / s to clean the rust and scale on the inner wall of the target pipeline.

[0052] S534. Observe the air source pressure drop to 0.4MPa, and then close the pressure valve, discharge valve, differential pressure adjustment fine-tuning valve and main control valve in sequence. Finally, close the release valve to complete one inner wall cleaning.

[0053] S535. Repeat the above steps to continuously clean the inner wall of the pipe. After repeating 10 times, stop the machine and check the descaling effect.

[0054] The specific steps of step S6 include: disconnecting the connecting flanges at both ends of the target pipeline, deploying an image acquisition device to check the scaling and rust removal effect on the inner wall, analyzing and judging, adjusting the operating pressure, determining the operating interval for stopping the machine again for inspection, and during the endoscopic inspection, when the cleaning effect at the tail end is worse than that at the front end compared to the state before cleaning, pre-feeding material to the middle position of the target pipeline, and then carrying out normal cleaning operations.

[0055] The beneficial effects of this invention are as follows:

[0056] This invention utilizes specialized equipment to regulate and control the airflow pressure difference, generating a "cyclone" within the target subsea pipeline. The continuous air supply from an energy storage device ensures stable pressure throughout the operation. The combined force of continuous thrust and centrifugal force creates a swirling flow along the spiral direction of the pipeline's inner wall, carrying materials and rust / debris towards the end of the operation until they are discharged from the pipeline. This solution is designed for descaling subsea pipelines with existing scale buildup, improving pipeline transport efficiency, enhancing the passability of internal detectors, preventing under-scale corrosion, and reducing the cost of subsequent subsea pipeline maintenance. Attached Figure Description

[0057] Figure 1 This is a flowchart of the steps of the present invention. Detailed Implementation

[0058] Example

[0059] like Figure 1 As shown, the specific steps of this embodiment include:

[0060] S1. On-site survey: Investigate the pipeline's direction, elevation difference, diameter changes, and bend locations; understand the scaling phenomenon in the pipeline; determine the placement and connection method of the descaling equipment; and determine the construction plan.

[0061] S2. Before construction, pipeline preparation must be completed. First, the fluid in the pipeline must be replaced. The target pipeline should be shut down and replaced with water, and then purged with nitrogen. Replace and remove the valves at both ends of the target pipeline. If there are no valves at the work points, the pipe must be cut and flanges welded.

[0062] S3. Use a CCTV inspection robot or probe endoscope to penetrate 50-100m into the pipeline, collect images, store them, and generate a report. Assess the condition of the pipeline wall and determine whether it meets the requirements for cyclone descaling.

[0063] S4. Connect the relevant pipelines. The specific arrangement in this embodiment is as follows:

[0064] 1. Arrange the cyclone generator and related auxiliary materials: the hoisting port location, a space of 2 x 8 meters, about 15 meters away from the subsea pipeline connection point.

[0065] 2. Freshwater interface: 1-inch quick-connect male connector, 20 meters away from the cyclone launcher.

[0066] 3. AC 220V power interface: 30 meters away from the loading dock.

[0067] 4. Set up a recycling device: There is a 2m×5m space next to the ball collection bucket, about 20 meters away from the pipeline discharge outlet.

[0068] All equipment should undergo individual testing before arrival to ensure safe operation. Upon arrival, equipment should be hoisted and positioned directly. Except for the two ports of the target pipeline, other process connection points can be pre-connected. At all flange connections, the sealing gaskets must not be misaligned, and bolts should be fully tightened and diagonally secured. For threaded connections with a risk of loosening, 12mm diameter bolts should be used. # The device is secured with wire. The exhaust system at the top of the recycling unit consists of double-layered louvers with an exhaust cross-sectional area of ​​2m². 2 A layer of oil-absorbing cotton should be added in the middle to absorb the volatile oil and oil components carried by water mist during operation.

[0069] In this embodiment, four air compressors and six energy storage devices are used, and the high-pressure hoses are DN250 high-pressure hoses.

[0070] The first four air compressors are connected to six energy storage devices via DN250 high-pressure hoses. These six energy storage devices are connected in series via DN250 high-pressure hoses and then to the inlet of the cyclone excitation system. Electrical personnel connect the DC24V control power supply for the cyclone excitation system to the starting battery of one of the air compressors. After the pipeline exploration is completed, the outlet of the cyclone excitation system is connected to the first end of the target pipeline via a DN250 wear-resistant high-pressure hose. The end of the target pipeline is connected to the recovery device via a DN250 wear-resistant high-pressure hose.

[0071] After the safety supervisor confirmed that the site met the safety production conditions, three air compressors were started sequentially to supply air to the energy storage device. When the air source pressure of the ignition system reached 0.4 MPa, the fine-tuning valve of the vortex ignition system was opened to 1 / 4 to introduce air into the target pipeline, and then opened to 1 / 2. When the pressure inside the pipeline reached 0.3 MPa, the fine-tuning valve was closed, the pressure was maintained, and all hoses and connecting flanges were checked for leaks. After the air source pressure reached 0.6 MPa, the three air compressors were immediately shut down. After confirming that there were no leaks in the hoses and connecting flanges, the release valve of the end recovery system was opened. First, the fine-tuning valve was opened to 1 / 4, and then the main control valve was opened. The rate at which the pipeline pressure gauge pointer dropped was observed to preliminarily determine the diameter reduction in the middle section of the target pipeline. When the air source pressure dropped to 0.4 MPa, the fine-tuning valve and the main control valve were closed.

[0072] After confirming the pipeline and equipment are in good condition, descaling of the S5 pipeline is carried out. First, a preliminary purging operation is performed. Three air compressors are started sequentially to supply air to the energy storage device. When the ignition system air source pressure reaches 0.4 MPa, the fine-tuning valve is opened to 1 / 4, supplying air into the target pipeline. It is then opened to 1 / 2, and when the pipeline pressure reaches 0.3 MPa, the fine-tuning valve is closed. Once the air source pressure reaches 0.6 MPa, the three air compressors are immediately shut down, and the release valve is opened. First, the fine-tuning valve is opened to 1 / 4, then the main control valve is opened, continuing to supply compressed air into the target pipeline for one purging operation. When the air source pressure drops to 0.4 MPa, the fine-tuning valve and the main control valve are closed. The operation time from opening the release valve to closing the main control valve is recorded, and the release valve is then closed. The above steps are repeated, gradually increasing the operating pressure to 0.8 MPa, until loose scale and deposited water on the inner wall surface are completely removed, i.e., no water or scale is discharged from the recovery device.

[0073] The next step is to descal and remove rust from the pipeline. Initially, a trial feeding should be conducted, and the amount of material added should be gradually increased after observation and judgment at the tail end. During the descaling process, every 3-4 cycles, a high-speed rotating airflow should be created without adding any material to accelerate the removal of residual material and rust. After filling the storage tank and water tank in advance, start the three air compressors in sequence to supply air to the energy storage device; open the feeding valves and introduce 20 kg of abrasive and 20 L of water into their respective metering tanks once, then close the two feeding valves. When the air source pressure of the ignition system reaches 0.4 MPa, open the fine-tuning valve to 1 / 4 to supply air into the target pipeline, then open it to 1 / 2. When the pipeline pressure reaches 0.3 MPa, close the fine-tuning valve. When the air source pressure reaches 0.6 MPa, shut down the air compressor and open the release valve. Sequentially open the feed valve, pressure valve, differential pressure adjustment valve (1 / 4), and main control valve, controlling the airflow rotation speed to approximately 12 m / s, to perform a trial cleaning of the rust and scale on the inner wall of the target pipeline. Observe the air source pressure drop to 0.4 MPa, then sequentially close the pressure valve, feed valve, differential pressure adjustment valve, and main control valve, and close the release valve to complete one trial cleaning of the inner wall. Record the time taken for the abrasive to reach the tail end and compare it with the time recorded during pipeline purging to mainly analyze and determine the blockage status of the middle section of the target pipeline. If the time difference is about half or the abrasive does not reach the tail end, stop adding abrasive and gradually increase the water volume to continue cleaning until the recorded times are similar, then proceed to the next step.

[0074] After trial cleaning, it was determined that the pipeline was not severely clogged, and deep descaling and derusting could be performed. Three air compressors were started sequentially to supply air to the energy storage device. When the ignition system air source pressure reached 0.4 MPa, the fine-tuning valve was opened to 1 / 4 of its opening to supply air into the target pipeline, then opened to 1 / 2. When the pipeline pressure reached 0.3 MPa, the fine-tuning valve was closed. The abrasive and coolant or water feeding valves were opened respectively, and 40 kg of abrasive and 40 liters of water were poured into their respective metering tanks once, then both feeding valves were closed. When the air source pressure reached 0.6 MPa, the air compressors were turned off, and the release valve was opened. The discharge valve, pressure valve, differential pressure adjustment fine-tuning valve (1 / 4), and main control valve were opened sequentially, controlling the airflow rotation speed at approximately 36 m / s to clean the rust and scale on the inner wall of the target pipeline. The air source pressure was observed to drop to 0.4 MPa, and the pressure valve, discharge valve, differential pressure adjustment fine-tuning valve, and main control valve were closed sequentially, and the release valve was closed, completing one cycle of inner wall cleaning. Repeat the above steps to continuously clean the inner wall of the pipe. After 10 cycles, stop the machine and check the descaling effect of step S6. Disconnect the flanges at both ends of the target pipe and use CCTV or a probe to check the descaling and rust removal effect on the inner wall. After analysis and judgment, appropriately increase or decrease the operating pressure and determine the interval between shutdowns for further inspection. During the endoscopic inspection, if the cleaning effect at the tail end is worse than that at the front end compared to the state before cleaning, pre-feed material to the middle position of the target pipe, i.e., operate for half the time recorded above, and then carry out normal cleaning operations.

[0075] In this solution, deep descaling and rust removal of pipelines is performed in cycles consisting of several cleaning operations, without checking the effectiveness within each cycle. Preferably, in this embodiment, the first cycle consists of 10 cycles, and the number of cycles in subsequent cycles is adjusted based on the check results.

[0076] After S7 cleaning is completed, process restoration will be carried out, and all process connections and equipment will be dismantled. All connecting bolts will be collected, categorized, and stored in a toolbox. Construction equipment, process connection pipes, auxiliary tools, etc., will be directly hoisted onto the transport ship. Pipelines will be handed over to the client, valves will be restored or broken pipe sections will be welded, inerted, and production will commence.

[0077] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for mechanical descaling of subsea pipelines using rotating airflow, characterized in that, include: S1. On-site survey: Investigate the structure and scaling phenomenon of the pipeline, determine the placement and connection method of the descaling equipment, and determine the overall construction plan. S2, pipeline replacement; S3. Pipeline inspection; S4. Connect the equipment and pipelines, install the cyclone generator, related auxiliary materials and recovery devices, connect the equipment to the pipeline end, and test the equipment for leaks. S5. Pipeline descaling: Based on the ventilation assessment of the pipeline scaling status, abrasive is added. After the initial purging of the pipeline and the pipeline descaling and rust removal work are carried out in sequence, the descaling effect in S6 is checked. Based on the inspection data of S6, the pipeline deep descaling and rust removal are carried out for 20 to 30 cycles. After the above cycles are completed, the pipeline is washed with water, purified and air-dried. S6. Descaling effect check; S7, Process restoration; The specific steps for the initial purging of the pipeline in step S5 include: S511. Perform internal wall purging, and start the air compressors in sequence to supply air to the energy storage device; S512. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 and supply gas into the target pipeline. Then adjust the opening of the fine adjustment valve to 1 / 2. S513. When the pipe pressure reaches 0.3 MPa, close the fine-tuning valve; S514. When the air source pressure reaches 0.6MPa, immediately shut down the air compressor, open the release valve, open the fine adjustment valve to 1 / 4, open the main control valve, and continue to input compressed air into the target pipeline to carry out a purging operation. S515. When the gas source pressure drops to 0.4MPa, close the fine-tuning valve and the main control valve, record the operation time from opening the release valve to closing the main control valve, and then close the release valve. S516. Repeat the above steps, gradually increasing the operating pressure to 0.8MPa until the loose scale and deposited water on the inner wall surface are completely removed. The specific steps for descaling and derusting in step S5 include: S521. Trial feeding is carried out on the target pipeline. After observation and judgment at the tail end, the amount of material input is gradually increased. S522. After filling the storage tank and water tank in advance, start the air compressor in sequence to supply air to the energy storage device, open the feeding valve, and introduce 20Kg of abrasive and 20L of water into each metering tank once, and then close the two feeding valves. S523. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 to supply gas into the target pipeline, and then adjust the fine adjustment valve to 1 / 2. S524. When the pipe pressure reaches 0.3 MPa, close the fine-tuning valve; S525. When the air source pressure reaches 0.6MPa, shut down the air compressor and open the relief valve; S526. Sequentially open the feeding valve, pressure valve, differential pressure adjustment fine-tuning valve and main control valve, control the airflow rotation speed at 12m / s, and perform trial cleaning of the rust and scale on the inner wall of the target pipeline. S527. When the air source pressure drops to 0.4MPa, close the pressure valve, discharge valve, differential pressure adjustment fine-tuning valve, and main control valve in sequence, and then close the release valve to complete one internal wall test cleaning. Record the time it takes for the abrasive to reach the tail end, compare the time it takes for the abrasive to reach the tail end with the time recorded when the pipeline is purged, and analyze and judge the blockage status of the middle section of the target pipeline. S528. When the time it takes for the abrasive to reach the end of the pipeline differs from the time recorded during pipeline purging by half, or when the abrasive does not reach the end of the pipeline, no more abrasive is added. The water volume is gradually increased to continue cleaning until the time it takes for the abrasive to reach the end of the pipeline and the time recorded during pipeline purging are within the difference range, and then a deep cleaning process is carried out.

2. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 1, characterized in that, include: Pipeline structure includes the pipeline's direction, elevation difference, diameter changes, and bend locations.

3. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 1, characterized in that, The pipeline replacement in step S2 specifically includes: S21. Replace the subsea water in the target pipeline; S22. Replace the nitrogen in the target pipeline; S23. Perform gas detection inside the target pipeline; S24. Replace and remove the valves at both ends of the target pipeline.

4. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 1, characterized in that: In step S3, an image acquisition device is deployed to capture and screenshot image data, and the acquired data is used to analyze the corrosion and blockage situation.

5. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 1, characterized in that: In step S4, the cyclone generator includes multiple air compressors, an energy storage device, and a cyclone excitation system. During setup, the multiple air compressors at the beginning are connected to multiple energy storage devices via high-pressure hoses. The energy storage devices are connected in series via high-pressure hoses and then connected to the air inlet of the cyclone excitation system. The starting battery of one air compressor is connected to the control power supply of the cyclone excitation system. After the pipeline exploration in step S3 is completed, the air outlet of the cyclone excitation system is connected to the beginning of the target pipeline via a wear-resistant high-pressure hose. The end of the target pipeline is connected to the recovery device via a wear-resistant high-pressure hose.

6. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 5, characterized in that, The specific steps of step S4 include: S41. After the safety supervisor confirms that the site meets the conditions for safe production, the air compressors are started in sequence to supply air to the energy storage device. S42. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine-tuning valve of the vortex excitation system to 1 / 4, and after gas is introduced into the target pipeline, open the fine-tuning valve of the vortex excitation system to 1 / 2. S43. When the pressure inside the pipe reaches 0.3 MPa, close the fine-tuning valve, maintain the pressure, and check for any leaks in the hoses and connecting flanges. S44. When the air source pressure reaches 0.6MPa, immediately shut down the air compressor, check and confirm that there are no leaks in the hoses and connecting flanges, and open the release valve of the end recovery system. S45. When the end-of-pipe recovery system release valve is opened to 1 / 4, open the main control valve and observe the rate of drop of the pipeline pressure gauge pointer to make a preliminary judgment on the diameter reduction of the middle section of the target pipeline. S46. When the gas source pressure drops to 0.4MPa, close the fine-tuning valve and the main control valve.

7. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 1, characterized in that, The specific steps for deep descaling and rust removal in step S5 include: S531. Start the air compressor in sequence to supply air to the energy storage device. When the gas source pressure of the excitation system reaches 0.4MPa, open the fine adjustment valve to 1 / 4 to supply air to the target pipeline. Then adjust the fine adjustment valve to 1 / 2. When the pipeline pressure reaches 0.3MPa, close the fine adjustment valve. S532. Open the abrasive and coolant feeding valves respectively, pour 40 kg of abrasive and 40 liters of water into their respective metering tanks once, and then close both feeding valves. S533. When the air source pressure reaches 0.6MPa, turn off the air compressor, open the release valve, and sequentially open the discharge valve, pressure valve, differential pressure adjustment fine-tuning valve and main control valve to control the airflow rotation speed at 36m / s to clean the rust and scale on the inner wall of the target pipeline. S534. Observe the air source pressure drop to 0.4MPa, and then close the pressure valve, discharge valve, differential pressure adjustment fine-tuning valve and main control valve in sequence. Finally, close the release valve to complete one inner wall cleaning. S535. Repeat the above steps to continuously clean the inner wall of the pipe. After repeating 10 times, stop the machine and check the descaling effect.

8. The method for mechanical descaling of subsea pipelines using rotating airflow according to claim 7, characterized in that, The specific steps of step S6 include: disconnecting the connecting flanges at both ends of the target pipeline, deploying an image acquisition device to check the scaling and rust removal effect on the inner wall, analyzing and judging, adjusting the operating pressure, determining the operating interval for stopping the machine again for inspection, and during the endoscopic inspection, when the cleaning effect at the tail end is worse than that at the front end compared to the state before cleaning, pre-feeding material to the middle position of the target pipeline, and then carrying out normal cleaning operations.

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