Deep sea multiphase flow auxiliary laser cleaning and welding composite device and method

Abstract

The invention discloses a deep sea multiphase flow auxiliary laser cleaning and welding composite device and method, and aims to solve the problem that a thick deposition layer on the surface of deep sea equipment is difficult to efficiently remove and repair. According to the device, seawater in deep sea is used as a liquid phase, and three-phase fluid is uniformly mixed through a pipeline mixer in combination with an onshore premixed abrasive injector and an air compressor, so that a high-speed multiphase flow injection system is formed. The gas phase provides power, the abrasive ejector enhances friction force, the liquid phase plays a role in cooling and cleaning, and the cleaning efficiency and quality are remarkably improved through the synergistic effect of the three. The multiphase flow spraying process provides ideal surface conditions for the subsequent ultrafast laser cleaning stage, it is ensured that the surface reaches the molecular-level cleanliness before welding, and the target area is repaired in combination with the laser welding technology. The method is suitable for efficient cleaning and repairing operation of equipment in the deep-sea complex environment, and a novel technical scheme is provided for deep-sea engineering maintenance.

Description

Technical Field

[0001] The present invention relates to underwater laser cleaning and welding technology in a deep-sea environment, and in particular to a deep-sea multiphase flow assisted laser cleaning and welding composite device and method. Background Art

[0002] With the increasing global energy demand and the gradual depletion of land resources, the development and utilization of marine resources has become the focus of attention of countries around the world. The ocean area accounts for more than 70% of the earth's surface and contains rich resources such as oil, natural gas, and minerals. It is of great significance to alleviate the energy crisis and promote economic development. However, the particularity of the deep-sea environment has brought many challenges to resource development, especially the construction and maintenance of underwater projects. Underwater cleaning and welding technology are crucial.

[0003] In deep-sea environments, especially in the daily operation and maintenance of underwater facilities such as submarine oil and gas platforms, deep-sea mineral mining equipment, and offshore wind power facilities, dirt, marine biological attachments, and corrosion products on the equipment surface often seriously affect the performance and safety of the equipment. In addition, structural damage and crack problems in deep-sea environments need to be repaired through efficient underwater welding technology. Traditional underwater cleaning and welding methods have problems such as low efficiency, environmental pollution, and high technical difficulty. Therefore, a more efficient and environmentally friendly cleaning and welding technology is urgently needed.

[0004] Laser beams can quickly remove materials and achieve molecular-level cleanliness due to their high energy density. As a non-contact process, laser processing does not produce mechanical stress and pollution, has relatively little impact on the surrounding environment, and can effectively protect the marine environment. However, current underwater laser cleaning technology still faces the following major problems:

[0005] (1) The thickness and adhesion of dirt in the deep-sea environment: The dirt layer on the surface of deep-sea equipment is often thick and tightly adhered. Traditional lasers are difficult to completely remove the dirt in one go, and often require repeated cleaning, which is time-consuming and labor-intensive.

[0006] (2) Limitation of cleaning effect by high-pressure environment: Due to the high pressure in the deep-sea environment, although the deposits have been detached after laser cleaning, it is not easy to completely separate from the surface of the equipment, and the residual dirt affects the subsequent welding quality.

[0007] (3) Environmental pollution issues: Traditional cleaning methods mostly rely on chemical cleaning agents, which pose a risk of pollution to the marine environment.

[0008] In the prior art, the Chinese patent with publication number CN1130705272B discloses an underwater welding machine device and method, which realizes the integrated operation of cleaning and welding by adopting a dual laser head; the Chinese patent with publication number CN166237341B discloses an underwater laser operation device with integrated laser cleaning function, which integrates the cleaning and welding processes into the same joint, thereby improving work efficiency. Although both technologies integrate laser cleaning and welding functions through local dry welding, their designs are mainly aimed at shallow water or conventional underwater environments. In deep-sea environments, the surface of the equipment is often covered with a thicker sediment layer, and the single laser cleaning in the prior art is difficult to meet actual needs. At the same time, although the CN166237341B patent takes into account the obstruction of laser transmission after the stripping of pollutants, its design fails to effectively solve the problem that pollutants are detached from the surface but not completely removed under high-pressure conditions in the deep sea. Because high pressure may cause sediment fragments to remain in the cleaning area, thus affecting the stability and quality of subsequent welding.

[0009] Therefore, it is urgent to develop a deep-sea multiphase flow-assisted laser cleaning and welding composite device and method to solve the above problems. "Multiphase flow" is reflected in the fact that the fluid is composed of liquid phase, solid phase and gas phase, in which the liquid phase is seawater in the deep-sea environment, which provides high kinetic energy impact as a cleaning matrix; the solid phase is premixed abrasive particles, which enhances the mechanical friction of cleaning; the gas phase is compressed air, which is used to reduce fluid viscosity, enhance jet penetration and promote the peeling and shedding of the sediment layer. The three phases are evenly mixed through an optimized pipeline mixer to form a high-speed multiphase flow. The synergistic effect significantly improves the cleaning efficiency and surface treatment quality of the deep-sea thick sediment layer, providing ideal surface conditions for the subsequent ultrafast laser fine cleaning stage; using natural seawater as a cleaning medium can effectively avoid the use of chemical cleaning agents and reduce the negative impact on the marine environment. In addition, the use of ultrafast lasers makes it possible to remove marine dirt without damaging the equipment coating, with higher cleaning efficiency. After cleaning, the repaired parts can also be laser welded to achieve effective integration of cleaning and welding. Summary of the invention

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions: A deep-sea multiphase flow-assisted laser cleaning and welding composite device, comprising:

[0011] A mobile shielding protection system, the mobile shielding protection system includes a mobile drainage cover and support legs fixed at the bottom thereof, the support legs provide a guiding function, an air inlet and an exhaust port are provided on the surface of the mobile drainage cover, the mobile drainage cover is connected to the external environment through the exhaust port, the exhaust port is used to discharge the treated water flow, an exhaust valve is fixedly connected to the surface of the mobile drainage cover, the exhaust valve is connected to the inside of the mobile drainage cover through the air inlet, the exhaust valve and the air inlet are used to discharge the seawater in the cover, to ensure the clarity and quality of the laser cleaning and welding areas, the mobile shielding protection system is used to provide a local dry operating environment and regional protection during laser cleaning and welding. Through flexible movement and precise positioning, the mobile shielding protection system includes a protective cover, which can isolate seawater and impurities, ensure efficient laser cleaning, and optimize environmental conditions during the welding stage, improving welding quality and structural reliability;

[0012] A fluid power generator and a water pump, wherein the fluid power generator and the water pump are both fixedly mounted on the top of the mobile drainage cover, and the fluid power generator and the water pump are connected through a pipeline, and the fluid power generator is connected to a pipeline mixer through a pipeline;

[0013] An abrasive ejector and a compressed air machine, wherein the abrasive ejector is connected to the bottom of the compressed air machine, and the air outlet of the compressed air machine is connected to the pipeline mixer;

[0014] The multiphase flow supply system is used to combine the high-speed seawater generated by the fluid power generator, the premixed abrasive ejector on land and the compressed air machine to form a multiphase flow, and achieve uniform mixing of the three phases through the pipeline mixer;

[0015] A laser cleaning and welding system, the laser cleaning and welding system comprising a laser, the laser being fixedly mounted in the middle of the inner cavity of a mobile drainage cover, the laser penetrating the mobile drainage cover and extending to the top thereof, a high-speed jet system being mounted on the outer surface of the laser, the high-speed jet system comprising a water jet and a baffle assembly, the water jet being used to jet high-pressure water flow to remove dirt on the surface of the equipment, the baffle assembly being used to block splashed sediments during the cleaning process, and protecting the laser head and other equipment, a pipeline mixer being fixedly connected to the upper surface of the water jet, the pipeline mixer generating turbulence and shear force through internal spiral blades to promote mixing of three-phase fluids of gas, liquid and solid, the laser emitting a laser beam, working in coordination with the water jet to perform underwater laser cleaning operations;

[0016] Underwater cameras, which are fixedly mounted at the four corners of the inner cavity of the mobile drainage cover and are connected to computer signals. The underwater cameras collect images of the cleaning and welding areas in real time and feed the data back to the computer for operators to monitor the cleaning and welding quality in real time;

[0017] The control system includes a controller, which is connected to the fluid power generator, laser, mobile drainage cover and pump through a connecting line. The controller is the core control unit of the system and controls these components in a unified manner. The controller controls the water flow, laser output and operation of the drainage cover according to a preset program. The control system is used to coordinate the operation of the multiphase flow supply system, high-speed multiphase flow injection system, laser cleaning and welding system, and mobile shielding protection system, and provides multi-mode parameter control and real-time monitoring functions.

[0018] A water jet inlet and a water jet outlet are respectively provided at both ends of the water jet. The water jet is connected to the interior of the pipeline mixer through the water jet inlet. The multiphase fluid of the pipeline mixer enters the water jet from the water jet inlet and is sprayed out at the water jet outlet to form a uniform planar multiphase flow.

[0019] The baffle assembly includes a fixed cover and a baffle, sliding guide rails are fixedly installed on both sides of the inner wall of the fixed cover, sliding grooves are opened on both sides of the baffle, the baffle is slidably connected to the surface of the sliding guide rails through the sliding grooves, and a buffer spring is fixedly connected between the end of the baffle and the inner wall of the fixed cover.

[0020] A pressure sensor is fixedly mounted on the surface of the fixed cover. The pressure sensor monitors the change of the water jet jet pressure and drives the expansion and contraction adjustment of the baffle assembly according to the pressure change signal.

[0021] Preferably, the multiphase flow supply system comprises:

[0022] The liquid phase supply module includes a regulator and a sensor. The regulator controls the water flow output pressure by adjusting the rotation speed of the regulating pump. The sensor is arranged at the outlet of the high-pressure pump to detect the water flow pressure and feed back the data to the controller to realize closed-loop control.

[0023] The gas-solid supply module can adjust the gas flow rate and solid abrasive conveying speed independently. It can be operated on land and optimize the gas and solid conveying conditions in real time according to the needs to achieve uniform mixing of the three-phase fluid. By accurately controlling the gas and solid flow rates, the gas, solid and liquid three phases are evenly proportioned in the mixer, improving the working efficiency and stability of the system. At the same time, the type and particle size of the solid abrasive can be flexibly changed to meet different cleaning and welding requirements, thereby ensuring the uniformity of the cleaning effect and enhancing the adaptability of the system.

[0024] Three-phase flow mixing module, the pipeline mixer generates turbulence and shear force through the internal spiral blades to promote the mixing of gas, liquid and solid three-phase fluids. Turbulence breaks the laminar state of the fluid, increases the mutual contact area, and thus improves the mixing efficiency. Gas, liquid and solid fluids quickly achieve uniform distribution through continuous interaction in the mixer. The design of the mixer optimizes the flow rate and flow direction to ensure that the three-phase fluid can be mixed efficiently and stably, providing an ideal fluid environment for deep-sea laser cleaning and welding.

[0025] Preferably, the water jet nozzle is designed with a rectangular cross-section, and the high-pressure water flow is distributed to multiple parallel slits through the equalizing cavity and the guide structure. Each slit ejects a linear water flow, which forms a uniform surface water flow after being ejected at the outlet. The inner wall of the nozzle is polished with high precision to reduce water turbulence and improve jet stability. Driven by high pressure, the surface water flow combines with the underwater abrasive ejector to flush the surface deposits at multiple points, generating efficient friction to remove stubborn dirt, which is suitable for wide-area cleaning of deep-sea environment equipment.

[0026] Preferably, the pulse width, energy and frequency of the laser are adjustable to meet the cleaning and welding requirements of different materials and dirt types.

[0027] Preferably, the drainage hood is remotely controlled by an onshore control system, and a propulsion device is used to achieve three-dimensional movement. The support feet at the bottom provide guidance. Combined with camera feedback, the operator can accurately adjust the position. The negative pressure system adjusts the adsorption force, reduces friction and ensures stable attachment.

[0028] Preferably, the length of the baffle assembly can be automatically adjusted according to the jet pressure of the water jet. The baffle is linked with the pressure sensor device to automatically extend and retract when the jet pressure of the water jet changes, so that it can effectively block debris while avoiding cleaning interference or blocking failure caused by the fixed position of the baffle. The slide rail ensures that the adjustment process is smooth and reliable, and adapts to the debris protection needs under different jet pressures.

[0029] A deep-sea multiphase flow assisted laser cleaning and welding composite method, applied to a deep-sea multiphase flow assisted laser cleaning and welding composite device, comprises the following steps:

[0030] Step 1: Throw the movable drainage cover into the sea, and use the controller to move the drainage cover to the part to be cleaned;

[0031] Step 2: Turn on the underwater camera to observe the cleaning area and feed the image back to the computer, select the appropriate pressure and abrasive ejector according to the actual situation of the equipment surface, start the fluid power generator and exhaust valve, and make the water jet eject the surface high-speed multiphase flow to clean the sediment on the equipment surface;

[0032] Step 3: Open the exhaust valve to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam;

[0033] Step 4: Observe the cleaning part again through the underwater camera and feed it back to the computer, select appropriate laser parameters according to the surface condition of the equipment, start the laser, and output the laser beam to clean the surface of the equipment;

[0034] Step 5: After cleaning is completed, the cleaning effect is observed through an underwater camera and fed back to the computer to determine whether the cleaning is qualified and whether welding repair is needed;

[0035] Step six: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0036] Preferably, in step 2, an underwater camera is disposed at each of the four corners of the drain cover to ensure a comprehensive and detailed observation of the equipment surface, thereby monitoring the cleaning process in real time.

[0037] Preferably, in step 2, the high-speed water flow uses natural seawater as the cleaning medium to avoid the use of chemical cleaning agents, thereby reducing the impact on the marine environment. At the same time, the injection pressure is adjustable to meet the cleaning needs of different equipment surfaces.

[0038] The present invention provides a deep-sea multiphase flow-assisted laser cleaning and welding composite device. It has the following beneficial effects:

[0039] The present invention provides a deep-sea multiphase flow-assisted laser cleaning and welding composite device, which can effectively solve the problems of thick sedimentary layers on the surface of deep-sea equipment and low efficiency of traditional cleaning methods. By using deep-sea seawater as the liquid phase, combining the gas phase and solid phase of solid abrasives and compressed air, and using a pipeline mixer to achieve uniform mixing of the three phases, a high-speed multiphase flow injection system is formed, which significantly improves the cleaning efficiency and quality, and provides ideal surface conditions for laser cleaning and welding processes. In addition, the use of seawater as a cleaning liquid avoids the use of chemical cleaning agents, reduces the risk of pollution and corrosion, and improves environmental protection. This technology effectively solves the problem of incomplete shedding of pollutants caused by high pressure in the deep-sea environment, ensures the quality of laser welding, improves the structural reliability of welding joints, and provides an innovative and environmentally friendly solution for efficient cleaning and repair of deep-sea equipment. The high-speed water flow pressure sprayed by the fluid power generator provided by the present invention and the pulse width, energy and frequency of the laser are all adjustable to meet the cleaning needs of different equipment surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a deep-sea multiphase flow-assisted laser cleaning device provided by the present invention;

[0041] Figure 2 is a schematic diagram of a laser cleaning and welding unit of the present invention;

[0042] Figure 3 It is a schematic diagram of the internal structure of the water jet of the present invention;

[0043] Figure 4 It is a schematic diagram of the structure of the baffle assembly of the present invention;

[0044] Figure 5 It is a cross-sectional view of the baffle assembly structure of the present invention.

[0045] In the figure: 1. Pump; 2. Fluid power generator; 3. Underwater camera; 4. Laser; 5. Water jet; 6. Baffle assembly; 61. Fixed cover; 62. Baffle; 63. Sliding guide rail; 64. Slide; 65. Buffer spring; 66. Pressure sensor; 7. Air inlet; 8. Exhaust; 9. Mobile drainage cover; 10. Controller; 11. Computer; 12. Exhaust valve; 13. Abrasive ejector; 14. Compressed air machine; 15. Pipeline mixer; 16. Water jet inlet; 17. Water jet outlet. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0047] The first embodiment, as Figure 1 As shown, the present invention provides a technical solution: a deep-sea multiphase flow-assisted laser cleaning and welding composite device, comprising:

[0048] A mobile drainage cover 9 and a support foot fixed at the bottom thereof, the support foot provides a guiding function, an air inlet 7 and an air outlet 8 are provided on the surface of the mobile drainage cover 9, the mobile drainage cover 9 is connected to the external environment through the air outlet 8, the air outlet 8 is used to discharge the treated water flow, an exhaust valve 12 is fixedly connected to the surface of the mobile drainage cover 9, the exhaust valve 12 is connected to the inside of the mobile drainage cover 9 through the air inlet 7, and is used to discharge the seawater in the cover to ensure the clarity and quality of the laser cleaning and welding areas;

[0049] Laser 4, laser 4 is fixedly installed in the middle of the inner cavity of the mobile drainage cover 9, laser 4 penetrates the mobile drainage cover 9 and extends to its top, the outer surface of laser 4 is sequentially installed with water jet 5 and baffle assembly 6 from top to bottom, water jet 5 is used to spray high-pressure water flow to remove dirt on the surface of the equipment. Baffle assembly 6 is used to block splashing sediments during the cleaning process, protect the laser head and other equipment, the upper surface of the water jet 5 is fixedly connected with a pipeline mixer 15, pipeline mixer 15 generates turbulence and shear force through internal spiral blades, promotes the mixing of gas, liquid and solid three-phase fluids, laser 4 emits a laser beam, and works in conjunction with water jet 5 to perform underwater laser cleaning operations;

[0050] The fluid power generator 2 and the water pump 1 are both fixedly mounted on the top of the mobile drainage cover 9, and the fluid power generator 2 and the water pump 1 are connected through a pipeline. The fluid power generator 2 and the water pump 1 work together to absorb seawater and pressurize it for injection. The fluid power generator 2 is connected to the pipeline mixer 15 through a pipeline;

[0051] An abrasive ejector 13 and a compressed air machine 14, wherein the abrasive ejector 13 is connected to the bottom of the compressed air machine 14, and the abrasive ejector 13 is driven by airflow to perform abrasive ejection auxiliary cleaning, and the air outlet of the compressed air machine 14 is connected to a pipeline mixer 15, which is used to mix the airflow with seawater and abrasive to form a multiphase flow, so as to improve the cleaning effect;

[0052] Underwater camera 3, the underwater camera 3 is fixedly installed at the four corners of the inner cavity of the mobile drainage cover 9, the underwater camera 3 is connected to the computer 11 by signal, the underwater camera 3 collects images of the cleaning and welding areas in real time, and feeds the data back to the computer 11, so that the operator can monitor the cleaning and welding quality in real time;

[0053] Controller 10, controller 10 is connected to fluid power generator 2, laser 4, mobile drainage cover 9 and pump 1 through connecting lines. Controller 10 serves as the core control unit of the system and performs unified control of these components. Controller 10 controls water flow, laser output, and operation of the drainage cover according to a preset program.

[0054] The second embodiment is based on the first embodiment. Figures 2 to 3 As shown, a water jet inlet 16 and a water jet outlet 17 are respectively provided at both ends of the water jet 5, and the water jet 5 is connected to the interior of the pipeline mixer 15 through the water jet inlet 16;

[0055] The water jet nozzle 5 is designed with a rectangular cross section. The uniform multiphase fluid from the pipeline mixer 15 enters from the top water jet water inlet 16. The high-pressure water flow is distributed to multiple parallel slits through the flow balancing cavity and the flow guide structure. Each slit ejects a linear water flow, which forms a uniform surface water flow after being ejected at the water jet outlet 17. The inner wall of the nozzle is polished with high precision to reduce water turbulence and improve jet stability. Driven by high pressure, the surface water flow combines with abrasives to flush surface deposits at multiple points, generating friction to peel off stubborn dirt.

[0056] The third embodiment is based on the first and second embodiments. Figures 2 to 5 As shown, the baffle assembly 6 includes a fixed cover 61 and a baffle 62. Sliding guide rails 63 are fixedly installed on both sides of the inner wall of the fixed cover 61. Slide grooves 64 are opened on both sides of the baffle 62. The baffle 62 is slidably connected to the surface of the sliding guide rail 63 through the slide grooves 64. A buffer spring 65 is fixedly connected between the end of the baffle 62 and the inner wall of the fixed cover 61.

[0057] A pressure sensor 66 is fixedly mounted on the surface of the fixed cover 61. The pressure sensor 66 monitors the change of the jet pressure of the water jet 5 and drives the expansion and contraction adjustment of the baffle 62 according to the pressure change signal.

[0058] The length of the baffle assembly 6 can be automatically adjusted according to the injection pressure of the water jet 5. The pressure sensor 66 monitors the change of the injection pressure of the water jet 5 in real time, and drives the expansion and contraction adjustment of the baffle assembly 6 according to the pressure change signal. The sliding guide rail 63 ensures that the baffle assembly 6 moves smoothly along the track during the adjustment process to avoid jamming or deviation, thereby ensuring that it is always in an effective shielding position.

[0059] When in use, the operator throws the mobile drainage cover 9 into the sea, and moves the mobile drainage cover to the part to be cleaned through the controller 10, then turns on the underwater camera 3 to observe the cleaning part and feeds the image back to the computer 11, selects the appropriate pressure and abrasive according to the actual situation of the equipment surface, starts the fluid power generator 2 and the compressed air machine 14, and makes the water jet 5 spray the surface high-speed multiphase flow to clean the sediment on the equipment surface;

[0060] At this time, the exhaust valve 12 is opened to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam. The cleaning part is observed again through the underwater camera 3 and fed back to the computer 11. According to the surface condition of the equipment, the appropriate laser parameters are selected, the laser 4 is started, and the laser beam is output to clean the surface of the equipment;

[0061] After cleaning is completed, the cleaning effect is observed by the underwater camera 3 and fed back to the computer 11 to determine whether the cleaning is qualified and whether welding repair is needed. If the cleaning is unqualified, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0062] A method for operating a deep-sea multiphase flow-assisted laser cleaning and welding composite device comprises the following steps:

[0063] Step 1: Put the mobile drainage cover 9 into the sea, and use the controller 10 to move the mobile drainage cover to the part to be cleaned;

[0064] Step 2: Turn on the underwater camera 3 to observe the cleaning part and feed the image back to the computer 11, select the appropriate pressure and abrasive according to the actual situation of the equipment surface, start the fluid power generator 2 and the compressed air machine 14, and make the water jet 5 spray the surface high-speed multiphase flow to clean the sediment on the equipment surface;

[0065] Step 3, opening the exhaust valve 12 to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam;

[0066] Step 4: observe the cleaning part again through the underwater camera 3 and feed back to the computer 11, select appropriate laser parameters according to the surface condition of the equipment, start the laser 4, and output the laser beam to clean the surface of the equipment;

[0067] Step 5: After the cleaning is completed, the cleaning effect is observed by the underwater camera 3 and fed back to the computer 11 to determine whether the cleaning is qualified and whether welding repair is required;

[0068] Step six: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

[0069] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A deep-sea multiphase flow-assisted laser cleaning and welding composite device, characterized in that: include: A mobile shielding protection system, the mobile shielding protection system comprising a mobile drainage cover (9) and a support leg fixed at the bottom thereof, the surface of the mobile drainage cover (9) being provided with an air inlet (7) and an air outlet (8), the mobile drainage cover (9) being connected to the external environment via the air outlet (8); A laser cleaning and welding system, the laser cleaning and welding system comprising a laser (4), the laser (4) being fixedly mounted in the middle of the inner cavity of a mobile drainage cover (9); A fluid power generator (2) and a water pump (1), wherein the fluid power generator (2) and the water pump (1) are both fixedly mounted on the top of the mobile drainage cover (9), and the fluid power generator (2) and the water pump (1) are connected via a pipeline, and the fluid power generator (2) is connected to a pipeline mixer (15) via a pipeline; An abrasive ejector (13) and a compressed air machine (14), wherein the abrasive ejector (13) is connected to the bottom of the compressed air machine (14), and the air outlet of the compressed air machine (14) is connected to a pipeline mixer (15); An underwater camera (3), the underwater camera (3) being fixedly mounted at the four corners of the inner cavity of the mobile drainage cover (9), and the underwater camera (3) being connected to a computer (11) via a signal; A control system, the control system comprising a controller (10), the controller (10) being connected to a fluid power generator (2), a laser (4), a mobile drainage cover (9) and a water pump (1) via connecting lines; A multiphase flow supply system, the multiphase flow supply system is used to combine the high-speed seawater generated by the fluid power generator (2), the solid-phase abrasive ejected by the abrasive ejector (13) and the gas-phase compressed air ejected by the air compressor (14) to form a multiphase flow, and to uniformly mix the three phases through a pipeline mixer (15); The multiphase flow supply system includes: A liquid supply module, the liquid supply module includes a regulator and a sensor, the regulator controls the water flow output pressure by adjusting the rotation speed of the regulating pump, and the sensor is arranged at the outlet of the high-pressure pump to detect the water flow pressure and feed the data back to the controller; A gas-solid supply module, which is used to adjust the gas flow rate and the solid abrasive conveying speed to achieve mixing of the three-phase fluid; The three-phase flow mixing module is used to adjust the gas flow rate and the solid abrasive conveying speed, and mix the gas, liquid and solid three-phase fluids.

2. A deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 1, characterized in that: An exhaust valve (12) is fixedly connected to the surface of the mobile drainage cover (9), and the exhaust valve (12) is connected to the interior of the mobile drainage cover (9) through an air inlet (7).

3. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 1, characterized in that: The laser (4) penetrates the movable drainage cover (9) and extends to the top thereof; a water jet (5) and a baffle assembly (6) are sequentially mounted on the outer surface of the laser (4) from top to bottom; and a pipeline mixer (15) is fixedly connected to the upper surface of the water jet (5).

4. A deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 3, characterized in that: The two ends of the water jet (5) are respectively provided with a water jet inlet (16) and a water jet outlet (17), and the water jet (5) is connected to the interior of the pipeline mixer (15) through the water jet inlet (16).

5. The deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 3, characterized in that: The baffle assembly (6) comprises a fixed cover (61) and a baffle (62), wherein sliding guide rails (63) are fixedly installed on both sides of the inner wall of the fixed cover (61), and sliding grooves (64) are opened on both sides of the baffle (62), and the baffle (62) is slidably connected to the surface of the sliding guide rails (63) through the sliding grooves (64), and a buffer spring (65) is fixedly connected between the end of the baffle (62) and the inner wall of the fixed cover (61).

6. A deep-sea multiphase flow-assisted laser cleaning and welding composite device according to claim 5, characterized in that: A pressure sensor (66) is fixedly mounted on the surface of the fixed cover (61), and the pressure sensor (66) monitors the change in the spray pressure of the water knife (5) and drives the expansion and contraction adjustment of the baffle assembly according to the pressure change signal.

7. A deep-sea multiphase flow-assisted laser cleaning and welding composite method, characterized in that: The following steps are involved: Step 1: throw the movable drainage cover (9) into the sea, and move the drainage cover to the part to be cleaned through the controller (10); Step 2: Turn on the underwater camera (3) to observe the cleaning area and feed the image back to the computer (11), select appropriate pressure and solid abrasive according to the actual situation of the equipment surface, start the fluid power generator (2) and the compressed air machine (14), and make the water knife (5) spray a planar high-speed multiphase flow to clean the sediment on the equipment surface; Underwater cameras (3) are respectively arranged at four corners of the drainage cover; Step 3, opening the exhaust valve (12) to discharge the seawater and sediment in the cover to prevent the seawater and pollutants from affecting the transmission quality of the laser beam; Step 4: observe the cleaning area again through the underwater camera (3) and feed back to the computer (11), select appropriate laser parameters according to the surface condition of the equipment, start the laser (4), and output the laser beam to clean the surface of the equipment; Step 5: After the cleaning is completed, the cleaning effect is observed by the underwater camera (3) and fed back to the computer (11) to determine whether the cleaning is qualified; Step six: If the cleaning is unsatisfactory, high-speed water flow and laser cleaning can be performed again; if welding repair is required, laser repair can be performed.

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