An underwater laser cutting system capable of efficiently removing aerosols

Abstract

The application relates to an underwater laser cutting system capable of efficiently removing aerosols and belongs to the technical field of radioactive metal cutting. The application solves the problem that the existing device for underwater cutting of radioactive contaminated structures in a reactor has poor removal effect on radioactive aerosol particles. The underwater laser cutting assembly is used for underwater cutting of a to-be-cut piece, the micro-nano bubble generating assembly is used for sucking the gas carrying radioactive aerosols in a main cavity into a micro-nano bubble generator, mixing the gas with water from the main cavity in the micro-nano bubble generator, discharging the micro-nano bubbles into the main cavity after the micro-nano bubbles are formed, and the electrically charged spraying assembly is used for spraying liquid drops with static electricity into the main cavity. The radioactive contaminated structure in the reactor can be disintegrated, removed and scrapped underwater, the radioactive aerosol particles generated in the cutting can be efficiently removed, the radioactive pollution to the environment is prevented, and the safety of the public and the operating personnel is ensured.

Description

Technical Field

[0001] This invention relates to an underwater laser cutting system capable of efficiently removing aerosols, belonging to the field of radioactive metal cutting technology. Background Technology

[0002] Nuclear facility decommissioning refers to the administrative and technical actions taken to enable the nuclear facility and its site to be reused after a nuclear facility has ceased operation due to the expiration of its service life, damage caused by an accident, or other reasons, in order to fully consider the health and safety of staff and the public and environmental protection.

[0003] During the decommissioning of nuclear power units, it is necessary to dismantle, dismantle, and decommission the radioactively contaminated structures and residual nuclear fuel of the reactor underwater. Due to the special nature of the materials being cut, safe, high-quality, and precise underwater cutting technology is required. Currently, the more mature underwater cutting methods mainly include high-temperature arc plasma cutting, high-temperature flame cutting, and laser cutting, among which laser cutting offers high metal cutting quality and efficiency.

[0004] However, during underwater cutting, the contamination layer on the surface of the reactor internals will melt and sublimate under the action of high-temperature laser, and then form a large number of submicron-sized radioactive aerosol particles upon cooling. These radioactive aerosols should be suppressed and removed in a confined space to prevent them from being released into the environment and causing radioactive pollution.

[0005] Among existing patents, patent CN112620837B provides a vertical electric spark underwater cutting device for spent fuel assemblies in nuclear power plants, enabling localized cutting of spent fuel assemblies. However, this invention does not consider the treatment of radioactive aerosols generated during the cutting process. To better dismantle, dismantle, and decommission underwater radioactive structures, there is an urgent need for an underwater laser cutting system capable of efficiently removing aerosols. This system would allow for precise cutting of radioactive contaminated structures within the reactor, while simultaneously efficiently removing radioactive aerosol particles generated during the cutting process, preventing the leakage of radioactive materials into the environment, and providing safety for the surrounding environment and nuclear power plant operators. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems and thereby provide an underwater laser cutting system capable of efficiently removing aerosols.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] An underwater laser cutting system capable of efficiently removing aerosols includes a main cavity filled with water, an underwater laser cutting component, a micro / nano bubble generating component, and a charged spraying component. The underwater laser cutting component cuts the workpiece underwater. The micro / nano bubble generating component draws gas carrying radioactive aerosols from the main cavity into its micro / nano bubble generator, where it mixes with water from the main cavity to form micro / nano bubbles, which are then discharged into the main cavity. The charged spraying component sprays electrostatically charged droplets into the main cavity.

[0009] Furthermore, the underwater laser cutting assembly includes a laser and a laser cutting head disposed in the water space of the main cavity. The laser cutting head is provided with a laser emitting head, a first convex lens, a second convex lens, a concave lens and a plane mirror arranged sequentially along the laser light path. The laser emitting head is connected to the laser via a laser cable. A laser cutting nozzle is connected to one end of the laser cutting head near the workpiece to be cut. The cavity between the plane mirror and the laser cutting nozzle is an auxiliary gas chamber. The auxiliary gas is delivered to the auxiliary gas chamber through a first air inlet pipe.

[0010] Furthermore, the auxiliary gas chamber is connected to the air compressor via the first intake pipe.

[0011] Furthermore, the air space of the main chamber is connected to the air compressor via a steam-water separator.

[0012] Furthermore, the micro-nano bubble generating assembly includes a first centrifugal pump, a gas collecting disk disposed in the gas space of the main cavity, and multiple micro-nano bubble generators disposed in parallel in the water space of the main cavity. The gas collecting disk and the second air inlets of the multiple micro-nano bubble generators are connected by a fourth air inlet pipe. The first centrifugal pump is connected to the liquid phase inlet of the micro-nano bubble generator and the water space of the main cavity through a pipeline.

[0013] Furthermore, the gas collecting disc has an inverted funnel-shaped structure.

[0014] Furthermore, the micro-nano bubble generator adopts a Venturi tube structure inside, in which the liquid phase inlet contraction angle and outlet expansion angle are both 30°, the inner diameter of the inlet section and the inner diameter of the outlet section are both 50mm, the inner diameter of the throat is 30mm, and the throat length is 10mm.

[0015] Furthermore, the charged spray assembly includes an atomizing nozzle fixed to the top of the main cavity and an inductive electrostatic ring disposed below the atomizing nozzle. The atomizing nozzle is connected to the water space of the main cavity through a pipeline and a second centrifugal pump, and the inductive electrostatic ring is powered by an electrostatic power supply disposed outside the main cavity.

[0016] Furthermore, the first centrifugal pump and the second centrifugal pump are the same centrifugal pump.

[0017] Furthermore, the distance between the inductive electrostatic ring and the atomizing nozzle is 5cm.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] In the underwater laser cutting process, a micro-nano bubble generator is introduced. Utilizing the characteristics of the Venturi tube structure, the gas carrying radioactive aerosol particles is processed into micro-nano bubbles containing aerosol particles, which then diffuse into the liquid phase. Under the influence of the properties of the micro-nano bubbles, the aerosol particles can be effectively removed. At the same time, the presence of micro-nano bubbles in the liquid phase can also improve the enrichment and adsorption degree of aerosol particles around the bubbles, thereby improving the pool washing removal efficiency of aerosols.

[0020] For aerosol particles in the main cavity gas space that were not removed by pool washing, a charged spray assembly is used for spray removal. Increasing the relative motion and collision capture probability between charged droplets and aerosol particles helps to improve the spray removal efficiency of aerosols.

[0021] The underwater laser cutting system of this invention enables the dismantling, removal, and disposal of radioactive contaminated reactor structures underwater during the decommissioning of nuclear power plants. It also efficiently removes radioactive aerosol particles generated during cutting, preventing radioactive pollution to the environment and ensuring the safety of the public and operators. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the underwater laser cutting assembly.

[0024] Figure 3 This is a cross-sectional schematic diagram of a micro / nano bubble generator;

[0025] Figure 4 This is a schematic diagram of the structure of the charged spray assembly.

[0026] In the picture:

[0027] 1. Main cavity; 2. Laser; 3. Laser cable; 4. Laser emitting head; 5. Laser cutting head; 6. First convex lens; 7. Second convex lens; 8. Convex lens; 9. Plane mirror; 10. Laser cutting nozzle; 11. Auxiliary gas chamber; 12. First air inlet; 13. First air inlet pipe; 14. Air compressor; 15. Third air inlet pipe; 16. Gas-water separator; 17. Second air inlet pipe; 19. First centrifugal pump; 21. Micro-nano bubble generator; 22. Second air inlet; 23. Fourth air inlet pipe; 24. Gas collection disk; 26. Atomizing nozzle; 27. Inductive electrostatic ring; 29. ​​Electrostatic power supply. Detailed Implementation

[0028] Specific implementation method one: Combining Figures 1-4 This description aims to clearly and completely illustrate the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that the descriptions of "left," "right," "left side," "right side," "upper part," "lower part," "top," and "bottom" in this invention are defined based on the orientation or positional relationships shown in the accompanying drawings. They are merely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the described structure must be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] An underwater laser cutting system capable of efficiently removing aerosols includes a main cavity 1 internally filled with water, an underwater laser cutting component, a micro-nano bubble generating component, and a charged spraying component. The underwater laser cutting component cuts the workpiece underwater. The micro-nano bubble generating component draws gas carrying radioactive aerosols from the main cavity 1 into its micro-nano bubble generator 21, where it mixes with water from the main cavity 1 to form micro-nano bubbles, which are then discharged into the main cavity 1. The charged spraying component sprays electrostatically charged droplets into the main cavity 1.

[0032] The main cavity 1 is enclosed and filled with water. The part below the water level is the water space, and the part above the water level is the air space.

[0033] In the underwater laser cutting process, a micro-nano bubble generator 21 is introduced. Utilizing the characteristics of the Venturi tube structure, the gas carrying radioactive aerosol particles is processed into micro-nano bubbles containing aerosol particles, which diffuse in the liquid phase. Under the influence of the properties of micro-nano bubbles, aerosol particles can be effectively removed. At the same time, the presence of micro-nano bubbles in the liquid phase can also improve the enrichment and adsorption degree of aerosol particles around the bubbles, thereby improving the pool washing removal efficiency of aerosols.

[0034] For aerosol particles in the main chamber 1 that were not removed by pool washing, a charged spray assembly is used for spray removal. Increasing the relative motion and collision capture probability between charged droplets and aerosol particles helps to improve the spray removal efficiency of aerosols.

[0035] The underwater laser cutting system of this invention enables the dismantling, removal, and scrapping of radioactive contaminated reactor structures underwater during the decommissioning of nuclear power plants. It also efficiently removes radioactive aerosol particles generated during cutting, preventing radioactive pollution to the environment and ensuring the safety of the public and operators.

[0036] The underwater laser cutting assembly includes a laser 2 and a laser cutting head 5 disposed within the water space of the main cavity 1. The laser cutting head 5 contains, sequentially along the laser beam path, a laser emitter 4, a first convex lens 6, a second convex lens 7, a concave lens 8, and a plane mirror 9. The laser emitter 4 is connected to the laser 2 via a laser cable 3. A laser cutting nozzle 10 is connected to the end of the laser cutting head 5 closest to the workpiece to be cut. The cavity between the plane mirror 9 and the laser cutting nozzle 10 serves as an auxiliary gas chamber 11, and auxiliary gas is supplied to the auxiliary gas chamber 11 through a first air inlet pipe 13. With this design, the laser 2 provides the laser source, which is transmitted to the laser cutting head 5 via the laser cable 3. The laser cutting head 5 uses two convex lenses and one concave lens 8 to converge the diverging laser source into a parallel light source, achieving the cutting function and effectively improving underwater cutting efficiency. Specifically, the divergent laser source is focused into a parallel laser with a larger spot size by the first convex lens 6, and then focused into a smaller spot size by the second convex lens 7. This smaller spot size is then refracted by the concave lens 8 to form a parallel laser source with a smaller spot size and higher energy density. By setting up an auxiliary gas chamber 11, a long dry zone is formed around the laser, effectively reducing energy dissipation in the liquid phase and facilitating observation of the cutting position, thereby improving the accuracy and quality of underwater cutting. The first air inlet 12 of the auxiliary gas chamber 11, connected to the first air inlet pipe 13, has a diameter of 3 mm. The laser cutting nozzle 10 is connected to the auxiliary gas chamber 11, and its inner diameter is 4.28 mm.

[0037] The auxiliary gas chamber 11 is connected to the air compressor 14 via the first air inlet pipe 13. High-pressure auxiliary gas is introduced into the auxiliary gas chamber 11 through the air compressor 14. The air compressor 14 is located outside the main cavity 1. The high-pressure gas in the auxiliary gas chamber 11 is ejected from the laser cutting nozzle 10 along with the parallel laser. The high-pressure gas dissipates the liquid around the laser path, forming a jet gas cavity drying zone, avoiding direct contact between the laser beam and water, reducing laser energy dissipation, and significantly improving cutting accuracy and quality.

[0038] The gas space of the main cavity 1 is connected to the air compressor 14 via a vapor-water separator 16. In this design, the gas space of the main cavity 1 is connected to the vapor-water separator 16 via a second air inlet pipe 17, and the vapor-water separator 16 is connected to the air compressor 14 via a third air inlet pipe 15. The auxiliary gas in the auxiliary gas chamber 11 is taken from the gas space within the main cavity 1, used to assist laser cutting, and then returns to the gas space in the form of a bubble cluster to balance the internal pressure of the main cavity 1. After being devastated by the vapor-water separator 16, the gas in the gas space is pressurized by the air compressor 14, and the pressurized gas enters the auxiliary gas chamber 11 through the first air inlet pipe 13.

[0039] The micro / nano bubble generating assembly includes a first centrifugal pump 19, a gas collecting disk 24 disposed in the gas space of the main cavity 1, and multiple micro / nano bubble generators 21 arranged in parallel in the water space of the main cavity 1. The gas collecting disk 24 and the second air inlets 22 of the multiple micro / nano bubble generators 21 are connected by a fourth air inlet pipe 23. The first centrifugal pump 19 is connected to the liquid phase inlet of the micro / nano bubble generators 21 and the water space of the main cavity 1 through a pipeline. With this design, the first centrifugal pump 19 is located outside the main cavity 1 and is connected to the water space of the main cavity 1 through a pipeline. The number of micro / nano bubble generators 21 is, for example, four. The diameter of the second air inlet 22 is 2 mm. The first centrifugal pump 19 provides a liquid dynamic head to the micro-nano bubble generator 21. According to Bernoulli's principle, a negative pressure is created at the second air inlet 22 of the micro-nano bubble generator 21. Gas containing aerosol particles in the main chamber 1 is drawn in by the inverted funnel-shaped gas collection disk 24 under this negative pressure and enters the micro-nano bubble generator through the fourth air inlet pipe 23. The inverted funnel-shaped gas collection disk 24 is installed directly above the underwater cutting area. Therefore, most of the gas carrying radioactive aerosols, after rising to the surface, is drawn into the micro-nano bubble generator 21 through the gas collection disk 24. Inside the Venturi tube, due to cavitation effects, it undergoes repeated impacts, compression, and shearing, ultimately forming micro-nano bubbles containing radioactive aerosols. Micro-nano bubbles possess characteristics such as large specific surface area, high gas-liquid interface mass transfer efficiency, and long residence time in the liquid phase. Compared to the bubble clusters formed by the assist gas in underwater laser cutting, the micro- and nano-bubbles formed by venturi tubes are much smaller. Smaller bubble sizes result in higher aerosol removal efficiency through pool washing. Simultaneously, micro- and nano-bubbles can increase the enrichment of micro- and nano-sized aerosol particles on the bubble surface and the mass transfer rate at the gas-liquid interface. Both of these effects of micro- and nano-bubbles effectively promote the pool washing efficiency of micro- and nano-sized aerosol particles.

[0040] The gas collection disk 24 has an inverted funnel shape. This design positions the gas collection disk 24 above the liquid level in the main cavity 1 and directly above the underwater cutting area, i.e., the rising area of ​​the bubble cluster generated by underwater laser cutting. This facilitates the collection of gas carrying radioactive aerosol particles generated during underwater laser cutting.

[0041] The micro / nano bubble generator 21 employs a Venturi tube structure. In this structure, the liquid inlet contraction angle and outlet expansion angle are both 30°, the inner diameter of the inlet section and outlet section are both 50mm, the throat inner diameter is 30mm, and the throat length is 10mm. This design achieves a higher number and efficiency of micro / nano bubbles compared to existing Venturi tubes.

[0042] The charged spray assembly includes an atomizing nozzle 26 fixed to the top of the main cavity 1 and an inductive electrostatic ring 27 disposed below the atomizing nozzle 26. The atomizing nozzle 26 is connected to the water space of the main cavity 1 via pipelines and a second centrifugal pump, and the inductive electrostatic ring 27 is powered by an electrostatic power supply 29 disposed outside the main cavity 1. With this design, the liquid used in the micro / nano bubble generator 21 and the liquid used in the atomizing nozzle 26 are both taken from the water space of the main cavity 1. The inductive electrostatic ring 27 charges the spray droplets from the atomizing nozzle 26. Because the inductive electrostatic ring 27 is close to the atomizing nozzle 26, the atomized droplets acquire an opposite charge to the aerosol particles when passing through the atomizing nozzle 26. Under the influence of Coulomb's gravity, this increases the probability of collision and capture between the droplets and aerosol particles, thus helping to improve the spray removal efficiency of radioactive materials.

[0043] The first centrifugal pump 19 and the second centrifugal pump are the same centrifugal pump. This design means that the micro-nano bubble generator 21 and the atomizing nozzle 26 share a single centrifugal pump.

[0044] The distance between the inductive electrostatic ring 27 and the atomizing nozzle 26 is 5cm.

[0045] Working principle:

[0046] The underwater laser cutting assembly's cutting method requires the use of auxiliary gas to purge the liquid around the laser path, forming a jet gas cavity drying zone to achieve precise cutting of the target structure. During the cutting process, high temperatures cause contaminants on the structural surface to melt and sublimate, subsequently generating a large number of submicron-sized radioactive waste aerosol particles upon cooling in the auxiliary gas. The bubble clusters formed by the auxiliary gas carry micro- and nano-sized radioactive aerosol particles upwards in the water. During this ascent, some aerosol particles enter the liquid phase through the gas-liquid interface and remain in the water, where they are removed by pool washing; others may escape into the main cavity's gas space.

[0047] The first centrifugal pump 19 provides a liquid dynamic head to the micro-nano bubble generator 21. According to Bernoulli's principle, a negative pressure is created at the second air inlet 22 of the micro-nano bubble generator 21. Gas containing aerosol particles in the main chamber 1 is drawn in by the inverted funnel-shaped gas collection disk 24 under this negative pressure and enters the micro-nano bubble generator through the fourth air inlet pipe 23. The inverted funnel-shaped gas collection disk 24 is installed directly above the underwater cutting area. Therefore, most of the gas carrying radioactive aerosols, after rising to the surface, is drawn into the micro-nano bubble generator 21 through the gas collection disk 24. Inside the Venturi tube, due to cavitation effects, it undergoes repeated impacts, compression, and shearing, ultimately forming micro-nano bubbles containing radioactive aerosols. Micro-nano bubbles possess characteristics such as large specific surface area, high gas-liquid interface mass transfer efficiency, and long residence time in the liquid phase. Compared to the bubble clusters formed by the assist gas in underwater laser cutting, the micro- and nano-bubbles formed by venturi tubes are much smaller. Smaller bubble sizes result in higher aerosol removal efficiency through pool washing. Simultaneously, micro- and nano-bubbles can increase the enrichment of micro- and nano-sized aerosol particles on the bubble surface and the mass transfer rate at the gas-liquid interface. Both of these effects of micro- and nano-bubbles effectively promote the pool washing efficiency of micro- and nano-sized aerosol particles.

[0048] For aerosol particles in the main chamber 1 that were not removed by pool washing, they can be removed by spraying using a charged spray assembly. A second centrifugal pump provides liquid head to the atomizing nozzle 26, forming a solid conical atomized spray area after the water passes through the nozzle 26. An inductive electrostatic ring 27 is positioned downstream of the atomizing nozzle 26, causing it to acquire the same charge as the aerosol particles. Consequently, the front end of the atomizing nozzle 26 acquires the opposite charge, causing the atomized droplets to acquire the opposite charge as they pass through the nozzle 26. Under the influence of Coulomb's gravity, this increases the relative motion and collision capture probability between the charged droplets and aerosol particles, thus improving the spray removal efficiency of aerosols.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An underwater laser cutting system capable of efficiently removing aerosols, characterized in that: The device includes an internally water-filled main cavity (1), an underwater laser cutting assembly, a micro-nano bubble generating assembly, and a charged spraying assembly. The underwater laser cutting assembly cuts the workpiece underwater. The micro-nano bubble generating assembly draws the gas carrying radioactive aerosol from the main cavity (1) into its micro-nano bubble generator (21), where it mixes with water from the main cavity (1) to form micro-nano bubbles, which are then discharged into the main cavity (1). The charged spraying assembly sprays electrostatically charged droplets into the main cavity (1). The main cavity (1) is enclosed and filled with water. The part below the water level is the water space, and the part above the water level is the air space. The micro-nano bubble generating assembly includes a first centrifugal pump (19), a gas collecting disk (24) disposed in the gas space of the main cavity (1), and multiple micro-nano bubble generators (21) disposed in parallel in the water space of the main cavity (1). The gas collecting disk (24) and the second air inlet (22) of the multiple micro-nano bubble generators (21) are connected by a fourth air inlet pipe (23). The first centrifugal pump (19) is connected to the liquid phase inlet of the micro-nano bubble generator (21) and the water space of the main cavity (1) through a pipeline. The micro-nano bubble generator (21) adopts a Venturi tube structure inside. The liquid phase inlet contraction angle and outlet expansion angle in the Venturi tube structure are both 30°, the inner diameter of the inlet section and the inner diameter of the outlet section are both 50mm, the inner diameter of the throat is 30mm, and the throat length is 10mm. The charged spray assembly includes an atomizing nozzle (26) fixed on the top of the main cavity (1) and an inductive electrostatic ring (27) disposed below the atomizing nozzle (26). The atomizing nozzle (26) is connected to the water space of the main cavity (1) through a pipeline and a second centrifugal pump. The inductive electrostatic ring (27) is powered by an electrostatic power supply (29) disposed outside the main cavity (1).

2. The underwater laser cutting system capable of efficiently removing aerosols according to claim 1, characterized in that: The underwater laser cutting assembly includes a laser (2) and a laser cutting head (5) disposed in the water space of the main cavity (1). The laser cutting head (5) is provided with a laser emitting head (4), a first convex lens (6), a second convex lens (7), a concave lens (8) and a plane mirror (9) arranged sequentially along the laser light path. The laser emitting head (4) is connected to the laser (2) through a laser cable (3). A laser cutting nozzle (10) is connected to one end of the laser cutting head (5) near the workpiece to be cut. The cavity between the plane mirror (9) and the laser cutting nozzle (10) is an auxiliary gas chamber (11). The auxiliary gas is delivered to the auxiliary gas chamber (11) through the first air inlet pipe (13).

3. The underwater laser cutting system capable of efficiently removing aerosols according to claim 2, characterized in that: The auxiliary gas chamber (11) is connected to the air compressor (14) through the first air inlet pipe (13).

4. The underwater laser cutting system capable of efficiently removing aerosols according to claim 3, characterized in that: The air space of the main cavity (1) is connected to the air compressor (14) through the steam-water separator (16).

5. The underwater laser cutting system capable of efficiently removing aerosols according to claim 1, characterized in that: The gas collection disc (24) has an inverted funnel-shaped structure.

6. The underwater laser cutting system capable of efficiently removing aerosols according to claim 1, characterized in that: The first centrifugal pump (19) and the second centrifugal pump are the same centrifugal pump.

7. The underwater laser cutting system capable of efficiently removing aerosols according to claim 1, characterized in that: The distance between the inductive electrostatic ring (27) and the atomizing nozzle (26) is 5 cm.

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