Boiler heating surface pipe oxide skin cleaning system and method based on cavitation water jet technology

Abstract

The invention relates to the technical field of boiler overhaul and maintenance of coal-fired power plants, and discloses a boiler heating surface pipe oxide skin cleaning system and method based on a cavitation water jet technology. The system is composed of a composite nozzle set, a high-pressure water supply pipeline, a low-pressure water supply pipeline, a high-pressure gas supply pipeline, a waste water recovery pipeline and the like, and through the synergistic effect of a central cavitation high-pressure nozzle and an annular low-pressure nozzle and in combination with gas-liquid two-phase flow and temperature regulation, the efficient cavitation effect is induced to strip oxide skin. During use, parameters are adjusted according to oxide skin conditions, and cleaning wastewater is recycled. The problems that a traditional cleaning technology is low in efficiency, pipe walls are damaged, and the environment is polluted are solved, and the method has the advantages of being efficient in cleaning, energy-saving, environmentally friendly, high in adaptability and the like and has remarkable economic benefits and engineering application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of overhaul and maintenance of coal-fired power plant boilers, and in particular relates to a system and method for cleaning oxide scales on boiler heating surface tubes based on cavitation water jet technology. Background Art

[0002] Cavitation water jet technology is based on the principles of fluid dynamics. It uses pressure fluctuations induced by high-speed flow to create cavitation bubbles within the liquid. When these bubbles collapse, they generate localized pressure and shock waves reaching thousands of atmospheres, accompanied by transient high temperatures. This energy release mechanism effectively breaks up and removes various surface deposits. Due to its significant advantages of non-contact operation, zero chemical pollution, and minimal substrate damage, this technology has been successfully applied in ship rust removal and metal surface treatment. However, there are no reports on its application in the removal of oxide scale from boiler heating surfaces.

[0003] Existing methods for cleaning oxidized boiler heating surface tubes include chemical cleaning and mechanical vibration, but each has its limitations. Chemical cleaning can corrode tube walls and shorten pipe life. The cleaning wastewater contains a large amount of harmful substances, which can pollute the environment if improperly handled. It is time-consuming and increases boiler downtime and maintenance costs. Mechanical vibration can negatively impact the strength and life of header fillet welds. Using high-pressure water at 70-220 MPa to blast away scale, while effective, is energy-intensive, can damage the base material, and reduce pipe strength. Summary of the Invention

[0004] The present invention provides a boiler heating surface tube oxide scale cleaning system and method based on cavitation water jet technology, aiming to solve the current problem of the urgent need for efficient, safe, environmentally friendly and adaptable cleaning technology and equipment for complex pipelines.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology is characterized by comprising a review nozzle group, a high-pressure water supply pipeline, a low-pressure water supply pipeline, a high-pressure gas supply pipeline, a wastewater recovery pipeline, and a tube sample to be cleaned; The review nozzle group is placed inside the pipe sample to be cleaned, and includes a central cavitation high-pressure nozzle and an annular low-pressure nozzle arranged on the circumference of the central cavitation high-pressure nozzle; The high-pressure water supply pipeline is connected to the central cavitation high-pressure nozzle and is used to provide high-pressure water to the pipe sample to be cleaned; The high-pressure gas supply pipeline is connected to the high-pressure water supply pipeline to form a gas-liquid two-phase flow with a gas volume fraction of 5-15%; The low-pressure water supply pipeline is connected to the annular low-pressure nozzle and is used to provide low-pressure water to the pipe sample to be cleaned; The wastewater recovery pipeline is placed at the bottom of the pipe sample to be cleaned and is used to recover the wastewater containing oxide scale after cleaning.

[0006] A further improvement of the present invention is that the high-pressure water supply pipeline includes a needle valve A, a high-pressure water pump, a safety valve A, a one-way valve A, a pressure regulating tank, a pressure sensor A, a heater A, a temperature sensor A and a flow meter A which are sequentially connected by a pipeline.

[0007] A further improvement of the present invention is that the high-pressure air supply pipeline includes a high-pressure air pump, a safety valve B, a needle valve B, a one-way valve B, a pressure sensor B and a flow meter B connected in sequence by pipelines; and the high-pressure air supply pipeline and the high-pressure water supply pipeline are connected through a three-way joint after the one-way valve A to form a gas-liquid two-phase flow with a gas volume fraction of 5-15%, which is used to enhance the impact force of the collapse of cavitation bubbles.

[0008] A further improvement of the present invention is that the low-pressure water supply pipeline includes a needle valve C, a low-pressure water pump, a safety valve C, a one-way valve C, a pressure sensor C, a heater B, a temperature sensor B and a flow meter C which are sequentially connected by a pipeline.

[0009] A further improvement of the present invention is that the wastewater recovery pipeline includes a wastewater recovery water tank, a needle valve D, a sedimentation water tank, a needle valve E, a filter, a needle valve F and a circulating water pump which are sequentially connected by a pipeline.

[0010] A further improvement of the present invention is that the central cavitation high-pressure nozzle is an angular nozzle with a progressive opening, an opening angle of 15~30°, and a ratio of the outlet section length to the throat diameter of 1.5-2.5. These structural parameters enable the water jet to form a supersonic cavitation effect at the outlet.

[0011] A further improvement of the present invention is that the annular low-pressure nozzle and the central cavitation high-pressure nozzle are coaxially arranged to form a low-speed circulation on the periphery of the jet to induce cavitation bubbles, and a spiral guide blade is arranged on the inner wall with a blade pitch of 10-20 mm and a helix angle of 45-60° to enhance the rotation effect of the low-pressure water flow and increase the generation density of cavitation bubbles.

[0012] A further improvement of the present invention is that the heater A and heater B are electromagnetic induction heaters with an operating frequency of 20-50kHz, which can accurately control the water temperature within the range of 50-80°C, and cooperate with temperature sensor A and temperature sensor B to form a closed-loop temperature control system.

[0013] A method for cleaning oxide scale on boiler heating surface tubes based on cavitation water jet technology, the method being based on the boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology, comprising the following steps: 1) Place the verification nozzle assembly inside the pipe sample to be cleaned, and adjust the opening and closing and flow of the high-pressure water supply pipeline, high-pressure air supply pipeline, and low-pressure water supply pipeline respectively through needle valve A, needle valve B, and needle valve C; start the high-pressure water pump, high-pressure air pump, and low-pressure water pump to transport high-pressure water, high-pressure air, and low-pressure water through the corresponding pipelines respectively. The high-pressure water and high-pressure air are mixed at the T-joint to form a gas-liquid two-phase flow; 2) Adjust heater A and heater B according to the type of oxide scale, and control the high-pressure water and low-pressure water temperatures between 50 and 80°C through feedback from temperature sensors A and B. Adjust the output pressures of the high-pressure water pump, high-pressure air pump, and low-pressure water pump based on real-time monitoring data from pressure sensors A, B, and C to maintain the high-pressure water pressure at 15 to 30 MPa, the high-pressure air pressure at 2 to 5 MPa, and the low-pressure water pressure at 3 to 8 MPa. 3) The central cavitation high-pressure nozzle ejects a gas-liquid two-phase supersonic jet, and the annular low-pressure nozzle forms a low-speed rotating annular flow. The interaction between the two induces cavitation bubbles, and the impact force generated by the collapse of the cavitation bubbles is used to peel off the oxide scale; 4) The wastewater containing oxide scale produced during cleaning falls into the wastewater recovery pipeline below; 5) During the cleaning process, monitor the data of flow meter A, flow meter B, and flow meter C in real time; when an abnormal increase in pipeline pressure is detected, immediately close safety valve A, safety valve B, and safety valve C, and stop the system operation for inspection.

[0014] A further improvement of the present invention is that the wastewater containing oxide scale produced by cleaning falls into the wastewater recovery tank of the wastewater recovery pipeline below, flows into the sedimentation tank through the needle valve D for sedimentation, and then passes through the needle valve E and the filter in turn, and is finally pumped to the low-pressure water supply pipeline by the circulating water pump through the needle valve F for recycling.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: Efficient cleaning: Through the coordinated design of the central cavitation high-pressure nozzle and the annular low-pressure nozzle, combined with the gas-liquid two-phase flow technology, a powerful cavitation impact force can be generated at a relatively low pressure (15-30MPa), which is more than 5 times higher than the traditional chemical cleaning method, and the removal rate of stubborn oxide scale can reach more than 95%.

[0016] Safe and reliable: It avoids the risk of chemical corrosion on the pipe wall and the risk of damage to the base material by high-pressure pure water jets. At the same time, through real-time monitoring and protection of pressure sensors and safety valves, it ensures safe and stable system operation and extends the service life of boiler pipes.

[0017] Energy saving and environmental protection: wastewater is recycled, precipitated and filtered, reducing water waste and wastewater discharge; compared with high-pressure pure water jet, energy consumption is reduced, which is in line with the concept of green environmental protection.

[0018] Strong adaptability: It can adapt to boiler heating surface tubes with different diameters from DN20 to DN500, as well as complex pipe structures such as elbows and reducers, greatly shortening boiler maintenance time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Schematic diagram of the system structure of the present invention Description of reference numerals: 1 is the pipe sample to be cleaned; 2 is the central cavitation high-pressure nozzle; 3 is the annular low-pressure nozzle; 4 is the needle valve A; 5 is the high-pressure water pump; 6 is the safety valve A; 7 is the one-way valve A; 8 is the pressure-stabilizing tank; 9 is the pressure sensor A; 10 is the heater A; 11 is the temperature sensor A; 12 is the flow meter A; 13 is the high-pressure air pump; 14 is the safety valve B; 15 is the needle valve B; 16 is the one-way valve B; 17 is the pressure sensor B; 18 is the flow meter B; 19 is the needle valve C; 20 is the low-pressure water pump; 21 is the safety valve C; 22 is the one-way valve C; 23 is the pressure sensor C; 24 is the heater B; 25 is the temperature sensor B; 26 is the flow meter C; 27 is the wastewater recovery tank; 28 is the needle valve D; 29 is the sedimentation tank; 30 is the needle valve E; 31 is the filter; 32 is the needle valve F; 33 is the circulating water pump. DETAILED DESCRIPTION

[0021] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0024] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0025] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0026] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0027] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0029] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Example 1 like Figure 1 As shown, the boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology provided by the present invention is characterized by comprising a review nozzle group, a high-pressure water supply pipeline, a low-pressure water supply pipeline, a high-pressure air supply pipeline, a wastewater recovery pipeline, and a tube sample to be cleaned; The review nozzle assembly is placed inside the pipe sample 1 to be cleaned, and includes a central cavitation high-pressure nozzle 2 and an annular low-pressure nozzle 3 arranged in the circumference of the central cavitation high-pressure nozzle 2; The high-pressure water supply pipeline is connected to the central cavitation high-pressure nozzle 2 and is used to provide high-pressure water to the pipe sample 1 to be cleaned; The high-pressure gas supply pipeline is connected to the high-pressure water supply pipeline to form a gas-liquid two-phase flow with a gas volume fraction of 5-15%; The low-pressure water supply pipeline is connected to the annular low-pressure nozzle 3 and is used to provide low-pressure water to the pipe sample 1 to be cleaned; The wastewater recovery pipeline is placed at the lower part of the pipe sample 1 to be cleaned, and is used to recover the wastewater containing oxide scale after cleaning.

[0032] In this embodiment, the high-pressure water supply pipeline includes a needle valve A4, a high-pressure water pump 5, a safety valve A6, a one-way valve A7, a pressure-surge tank 8, a pressure sensor A9, a heater A10, a temperature sensor A11 and a flow meter A12, which are connected in sequence by pipelines.

[0033] In this embodiment, the high-pressure air supply pipeline includes a high-pressure air pump 13, a safety valve B14, a needle valve B15, a one-way valve B16, a pressure sensor B17 and a flow meter B18, which are connected in sequence by pipelines; and the high-pressure air supply pipeline and the high-pressure water supply pipeline are connected through a three-way joint after the one-way valve A7 to form a gas-liquid two-phase flow with a gas volume fraction of 5-15%, which is used to enhance the impact force of the collapse of cavitation bubbles.

[0034] In this embodiment, the low-pressure water supply pipeline includes a needle valve C19, a low-pressure water pump 20, a safety valve C21, a one-way valve C22, a pressure sensor C23, a heater B24, a temperature sensor B25, and a flow meter C26, which are sequentially connected by a pipeline; In this embodiment, the wastewater recovery pipeline includes a wastewater recovery tank 27, a needle valve D28, a sedimentation water tank 29, a needle valve E30, a filter 31, a needle valve F32 and a circulating water pump 33 which are sequentially connected by pipelines.

[0035] In this embodiment, the central cavitation high-pressure nozzle 2 is an angular nozzle with a progressive opening, an opening angle of 15-30°, and a ratio of the outlet section length to the throat diameter of 1.5-2.5. These structural parameters enable the water jet to form a supersonic cavitation effect at the outlet.

[0036] In this embodiment, the annular low-pressure nozzle 3 and the central cavitation high-pressure nozzle 2 are coaxially arranged to form a low-speed circulation on the periphery of the jet to induce cavitation bubbles. A spiral guide blade is provided on the inner wall with a blade pitch of 10-20 mm and a helix angle of 45-60° to enhance the rotation effect of the low-pressure water flow and increase the generation density of cavitation bubbles.

[0037] In this embodiment, the heater A10 and the heater B24 are electromagnetic induction heaters with an operating frequency of 20-50 kHz, which can accurately control the water temperature within the range of 50-80°C, and cooperate with the temperature sensor A11 and the temperature sensor B25 to form a closed-loop temperature control system.

[0038] In this embodiment, the wastewater recovery tank 27 in the wastewater recovery pipeline is placed at the lower part of the pipe sample 1 to be cleaned, and is used to recover the wastewater containing oxide scale after cleaning.

[0039] Example 2 like Figure 1 As shown, the boiler heating surface tube oxide scale cleaning method based on cavitation water jet technology provided by the present invention is characterized in that the method is based on the boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 5, and includes the following steps: 1) Place the verification nozzle assembly inside the pipe sample to be cleaned, and adjust the opening and closing and flow of the high-pressure water supply pipeline, high-pressure air supply pipeline, and low-pressure water supply pipeline respectively through needle valve A4, needle valve B15, and needle valve C19; start the high-pressure water pump 5, high-pressure air pump 13, and low-pressure water pump 20 to transport high-pressure water, high-pressure air, and low-pressure water through the corresponding pipelines respectively. The high-pressure water and high-pressure air are mixed at the T-joint to form a gas-liquid two-phase flow; 2) Adjust heater A10 and heater B24 according to the type of oxide scale. Control the high-pressure water and low-pressure water temperatures between 50°C and 80°C through feedback from temperature sensors A11 and B25. Adjust the output pressures of high-pressure water pump 5, high-pressure air pump 13, and low-pressure water pump 20 based on real-time monitoring data from pressure sensors A9, B17, and C23 to maintain the high-pressure water pressure between 15 and 30 MPa, the high-pressure air pressure between 2 and 5 MPa, and the low-pressure water pressure between 3 and 8 MPa. 3) The central cavitation high-pressure nozzle 2 ejects a gas-liquid two-phase supersonic jet, and the annular low-pressure nozzle 3 forms a low-speed rotating annular flow. The interaction between the two induces cavitation bubbles, and the impact force generated by the collapse of the cavitation bubbles is used to peel off the oxide scale; 4) The wastewater containing oxide scale produced during cleaning falls into the wastewater recovery pipeline below; 5) During the cleaning process, monitor the data of flow meter A12, flow meter B18, and flow meter C26 in real time; when an abnormal increase in pipeline pressure is detected, immediately close safety valve A6, safety valve B14, and safety valve C21, and stop the system operation for inspection.

[0040] In this embodiment, the wastewater containing oxide scale produced by cleaning falls into the wastewater recovery tank 27 of the wastewater recovery pipeline below, flows into the sedimentation water tank 29 through the needle valve D for sedimentation, and then passes through the needle valve E30 and the filter in turn, and finally is sent to the low-pressure water supply pipeline by the circulating water pump 33 through the needle valve F32 for recycling.

[0041] Example 3 1) Clean up objects: Coal-fired unit superheater pipe, nominal diameter DN64, main chemical composition is Fe3O4.

[0042] 2) Cleanup parameters: High-pressure water circuit: Start the high-pressure water pump, adjust the needle valve A, stabilize the system pressure at 15MPa, and control the flow rate to 50L / min High-pressure gas line: Turn on the high-pressure gas pump, adjust the gas pressure to 3MPa through needle valve B, and set the gas volume fraction to 8% Low-pressure water circuit: The low-pressure water pump is matched with needle valve C to keep the working pressure at 5MPa and the flow output at 25L / min Temperature control: High-pressure water and low-pressure water are preheated by heater A and heater B respectively, and the water temperature of both channels is maintained at 65°C simultaneously. 3) Cleaning Process: The verification nozzle assembly is precisely placed into the target pipeline, and the cleaning system is activated according to preset parameters. The central cavitating high-pressure nozzle emits a supersonic gas-liquid two-phase jet, which synergizes with the low-speed rotating annular flow generated by the annular low-pressure nozzle, inducing a dense cluster of cavitation bubbles within the pipeline. The instantaneous impact force generated by the collapse of the cavitation bubbles effectively strips away the oxide scale adhering to the pipe wall. The stripped oxide scale falls into the recovery tank with the wastewater, where it undergoes sedimentation and multi-stage filtration for recycling.

[0043] 4) Cleaning Results: The 150-meter pipeline was cleaned after three hours of continuous operation. Testing showed a 96% scale removal rate, leaving the pipeline's interior intact. Ideal cleaning results were achieved, particularly in complex elbow areas, fully verifying the system's suitability.

[0044] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0045] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology is characterized by: Including the review nozzle group, high-pressure water supply pipeline, low-pressure water supply pipeline, high-pressure gas supply pipeline, wastewater recovery pipeline, and pipe samples to be cleaned; The review nozzle group is placed inside the pipe sample to be cleaned, and includes a central cavitation high-pressure nozzle and an annular low-pressure nozzle arranged on the circumference of the central cavitation high-pressure nozzle; The high-pressure water supply pipeline is connected to the central cavitation high-pressure nozzle and is used to provide high-pressure water to the pipe sample to be cleaned; The high-pressure gas supply pipeline is connected to the high-pressure water supply pipeline to form a gas-liquid two-phase flow with a gas volume fraction of 5-15%; The low-pressure water supply pipeline is connected to the annular low-pressure nozzle and is used to provide low-pressure water to the pipe sample to be cleaned; The wastewater recovery pipeline is placed at the bottom of the pipe sample to be cleaned and is used to recover the wastewater containing oxide scale after cleaning.

2. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 1 is characterized in that: The high-pressure water supply pipeline includes a needle valve A, a high-pressure water pump, a safety valve A, a one-way valve A, a pressure-stabilizing tank, a pressure sensor A, a heater A, a temperature sensor A and a flow meter A, which are connected in sequence by pipelines.

3. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 2 is characterized in that: The high-pressure gas supply pipeline includes a high-pressure gas pump, a safety valve B, a needle valve B, a one-way valve B, a pressure sensor B and a flow meter B connected in sequence by pipelines; and the high-pressure gas supply pipeline and the high-pressure water supply pipeline are connected through a three-way joint after the one-way valve A to form a gas-liquid two-phase flow, and the gas volume fraction is 5-15%.

4. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 3 is characterized in that: The low-pressure water supply pipeline includes a needle valve C, a low-pressure water pump, a safety valve C, a one-way valve C, a pressure sensor C, a heater B, a temperature sensor B and a flow meter C which are connected in sequence by pipelines.

5. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 4 is characterized in that: The wastewater recovery pipeline includes a wastewater recovery tank, a needle valve D, a sedimentation water tank, a needle valve E, a filter, a needle valve F and a circulating water pump which are sequentially connected by pipelines.

6. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 5 is characterized in that: The central cavitation high-pressure nozzle is an angular nozzle with a progressive opening, an opening angle of 15-30 degrees, and a ratio of the outlet section length to the throat diameter of 1.5-2.

5.

7. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 5 is characterized in that: The annular low-pressure nozzle and the central cavitation high-pressure nozzle are coaxially arranged to form a low-speed circulation on the periphery of the jet to induce cavitation bubbles. A spiral guide blade is arranged on the inner wall, with a blade pitch of 10-20mm and a spiral angle of 45-60°.

8. The boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology according to claim 5 is characterized in that: The heater A and heater B are electromagnetic induction heaters with an operating frequency of 20-50kHz, which can control the water temperature within the range of 50-80°C, and form a closed-loop temperature control system with temperature sensor A and temperature sensor B.

9. A method for cleaning oxide scale from boiler heating surface tubes based on cavitation water jet technology, characterized in that: The method is based on the boiler heating surface tube oxide scale cleaning system based on cavitation water jet technology as described in claim 5, and includes the following steps: 1) Place the verification nozzle assembly inside the pipe sample to be cleaned, and adjust the opening and closing and flow of the high-pressure water supply pipeline, high-pressure air supply pipeline, and low-pressure water supply pipeline respectively through needle valve A, needle valve B, and needle valve C; start the high-pressure water pump, high-pressure air pump, and low-pressure water pump to transport high-pressure water, high-pressure air, and low-pressure water through the corresponding pipelines respectively. The high-pressure water and high-pressure air are mixed at the T-joint to form a gas-liquid two-phase flow; 2) Adjust heater A and heater B according to the type of oxide scale, and control the high-pressure water and low-pressure water temperatures between 50 and 80°C through feedback from temperature sensors A and B. Adjust the output pressures of the high-pressure water pump, high-pressure air pump, and low-pressure water pump based on real-time monitoring data from pressure sensors A, B, and C to maintain the high-pressure water pressure at 15 to 30 MPa, the high-pressure air pressure at 2 to 5 MPa, and the low-pressure water pressure at 3 to 8 MPa. 3) The central cavitation high-pressure nozzle ejects a gas-liquid two-phase supersonic jet, and the annular low-pressure nozzle forms a low-speed rotating annular flow. The interaction between the two induces cavitation bubbles, and the impact force generated by the collapse of the cavitation bubbles is used to peel off the oxide scale; 4) The wastewater containing oxide scale produced during cleaning falls into the wastewater recovery pipeline below; 5) During the cleaning process, monitor the data of flow meter A, flow meter B, and flow meter C in real time; when an abnormal increase in pipeline pressure is detected, immediately close safety valve A, safety valve B, and safety valve C, and stop the system operation for inspection.

10. The method for cleaning oxide scale on boiler heating surface tubes based on cavitation water jet technology according to claim 9, characterized in that: The wastewater containing oxide scale produced by cleaning falls into the wastewater recovery tank of the wastewater recovery pipeline below, flows into the sedimentation tank through needle valve D for sedimentation, and then passes through needle valve E and filter in turn, and is finally pumped to the low-pressure water supply pipeline by the circulating water pump through needle valve F for recycling.

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