An integrated spray structure for internal shot peening of steam generator tube bundles

Abstract

The application belongs to the technical field of steam generator inspection and maintenance, and particularly relates to an integrated spraying structure for shot blasting and descaling inside a steam generator tube bundle, which comprises a sealing ring and a small spray gun. The sealing ring comprises a base body and a dovetail at the rear end of the base body. The base body is elastic and used for adhering to the mouth of a heat transfer tube. The front end of the small spray gun is provided with a dovetail groove and an installation internal thread on the outer side. The dovetail and the dovetail groove are in interference fit. The installation internal thread is used for connecting with an external supporting mechanism. The external supporting mechanism is used for supporting the small spray gun to be stable and not loose in position during operation. The nozzle of the small spray gun is in an elongated tube structure and used for extending into the heat transfer tube by more than 30 mm. The rear end of the small spray gun is provided with an installation external thread on the outer side. The installation external thread is used for connecting with the interface of a shot-compressed air conveying pipeline. The application solves the problems of insufficient sealing performance and low spraying efficiency of the spray gun in the prior art when spraying shots at high speed through the innovative structural design.

Description

Technical Field

[0001] This application belongs to the field of steam generator inspection and maintenance technology, specifically relating to an integrated shot blasting structure for shot blasting descaling inside steam generator tube bundles. Background Technology

[0002] Steam generator (evaporator) heat transfer tubes operate in a high-temperature, high-pressure environment for extended periods, making them prone to scale buildup on the inner walls due to corrosion products from the primary loop. This scale not only reduces heat transfer efficiency but can also lead to localized corrosion, causing tube wall rupture, compromising the safety boundary of the main loop, and potentially resulting in the spread of radioactive materials, thus impacting the safe operation of nuclear power plants. Shot peening removes the scale buildup by using high-speed shot to impact the inner walls of the heat transfer tubes, while simultaneously strengthening the surface of the inner walls to improve their corrosion resistance and wear resistance.

[0003] Existing shot peening technology still has some problems and limitations in practical applications: insufficient pipe sealing performance; when traditional spray guns spray shot at high speed, the shot is prone to splashing from the pipe opening, which not only affects the descaling effect but also generates foreign objects in the evaporator water chamber; low spraying efficiency; the spraying speed and shot distribution uniformity of traditional spray guns are poor, resulting in low descaling efficiency. Summary of the Invention

[0004] In view of this, this application provides an integrated spraying structure for shot peening and descaling inside the tube bundle of a steam generator. Through innovative structural design, it solves the problems of insufficient sealing performance and low spraying efficiency of the existing spray gun when spraying shot at high speed.

[0005] This application provides an integrated shot peening structure for internal shot peening and descaling of steam generator tube bundles. The integrated shot peening structure includes a sealing ring and a small spray gun. The sealing ring includes a base and a dovetail located at the rear end of the base. The base is elastic and fits snugly against the heat transfer tube openings. The front end of the small spray gun has a dovetail groove and an internal mounting thread. The dovetail and dovetail groove are interference-fitted. The internal mounting thread is used for connection to an external support mechanism. The external support mechanism is used to ensure the small spray gun remains stable and does not loosen during operation. The nozzle of the small spray gun has a slender tubular structure, allowing it to extend more than 30 mm into the heat transfer tube. The rear end of the small spray gun has an external mounting thread. The external mounting thread is used for connection to the interface of the shot-compressed air delivery pipeline.

[0006] In one specific embodiment of this application, the width of the dovetail is 0.05~0.2mm larger than the width of the dovetail groove.

[0007] In one specific embodiment of this application, the dovetail has a wedge-shaped protrusion structure. The dovetail groove has a wedge-shaped recess structure.

[0008] In one specific embodiment of this application, the sealing ring further includes a boss. The boss is disposed at the front end of the base.

[0009] In one specific embodiment of this application, the height of the boss is 2mm~3mm.

[0010] In one specific embodiment of this application, the small spray gun includes an inlet section, a rectifying section, an acceleration section, and an ejection section arranged coaxially. The inlet section is located at the rear end of the small spray gun and is used to introduce a mixture of shot and compressed air. The rectifying section is connected between the inlet section and the acceleration section. The acceleration section is connected between the rectifying section and the ejection section. The ejection section is located at the front end of the small spray gun.

[0011] In one specific embodiment of this application, the inlet section is a frustum-shaped flow channel, the rectification section is a cylindrical flow channel, and the acceleration section is an expansion-shaped flow channel.

[0012] In one specific embodiment of this application, the expansion angle of the acceleration segment is 6°~10°.

[0013] In one specific embodiment of this application, the sealing ring is made of high-hardness nitrile rubber.

[0014] In one specific embodiment of this application, the main body of the small spray gun is made of 3Cr13.

[0015] The beneficial effects of this technical solution are as follows: Through the interference fit design of the dovetail in the sealing ring and the dovetail groove on the small spray gun, a quick connection and stable fit between the sealing ring and the small spray gun are achieved, while ensuring their coaxiality. This improves the sealing performance of the integrated spray structure, prevents shot splashing, ensures the safety of the descaling process, and guarantees the reliability and functional stability of the overall structure connection. Furthermore, this quick-release design makes sealing ring replacement more convenient, enabling rapid replacement of vulnerable parts, simplifying equipment maintenance, and reducing the maintenance cost of the integrated spray structure. Simultaneously, the sealing ring design ensures a seal between the spray gun and the nozzle during spray gun firing, and prevents shot from scattering in case of accidents. The small spray gun design enables high-speed shot spraying within a confined space, achieving stability and high efficiency of the integrated spray structure under complex working conditions. In addition, by setting the nozzle to a slender tube structure, extending more than 30mm into the heat transfer tube, the impact of the tail airflow on the seal is reduced, ensuring shot peening effect while preventing shot leakage. Attached Figure Description

[0016] Figure 1 The diagram shown is a schematic diagram of an integrated shot peening structure for descaling inside a steam generator tube bundle, according to an embodiment of this application.

[0017] Figure 2 As shown Figure 1The diagram shows a cross-sectional schematic of an integrated shot peening structure for descaling inside a steam generator tube bundle.

[0018] Figure 3 As shown Figure 1 The diagram shows a schematic of the sealing ring in an integrated shot peening structure for descaling inside a steam generator tube bundle.

[0019] Figure 4 As shown Figure 1 The diagram shows a small spray gun in an integrated shot blasting structure for descaling inside a steam generator tube bundle.

[0020] Figure 5 The image shown is of this application. Figure 1 The diagram shows a working schematic of an integrated shot peening structure for descaling inside a steam generator tube bundle.

[0021] Figure 6 As shown Figure 5 An enlarged view of point A in the schematic diagram shown.

[0022] In the diagram, 100 is the sealing ring, 101 is the boss, 102 is the base, and 103 is the dovetail. 200. Small spray gun; 201. Launch section; 202. Acceleration section; 203. Rectification section; 204. Inlet section; 211. Nozzle; 212. Dovetail groove; 213. Internal mounting thread; 214. External mounting thread. 300. Tube sheet and heat transfer tubes; 400. External support structure. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] At least one embodiment of this application provides an integrated shot peening structure for shot peening descaling inside steam generator tube bundles, see reference. Figures 1 to 6This integrated shot peening structure for descaling the interior of a steam generator tube bundle includes a sealing ring 100 and a small spray gun 200. The sealing ring 100 includes a base 102 and a dovetail 103 located at the rear end of the base 102. The base 102 is elastic and is used for fitting the heat transfer tube opening. The front end of the small spray gun 200 has a dovetail groove 212 and an internal mounting thread 213. The dovetail 103 is interference-fitted with the dovetail groove 212. The internal mounting thread 213 is used for connection with an external support mechanism 400. The external support mechanism 400 is used to ensure the small spray gun 200 remains stable during operation. The nozzle 211 of the small spray gun 200 has a slender tube structure, allowing it to extend into the heat transfer tube by more than 30 mm. The rear end of the small spray gun 200 has an external mounting thread 214. The external mounting thread 214 is used for connection with the interface of the shot-compressed air delivery pipeline.

[0025] It should be noted that the outer diameter of the nozzle 211 is slightly smaller than the inner diameter of the heat transfer tube, as long as it can extend into the heat transfer tube by more than 30mm. Figure 5 The tube sheet and heat transfer tubes 300 are part of the steam generator, while other components are introduced externally. Therefore, the tube sheet and heat transfer tubes 300 can be regarded as a single component.

[0026] According to the technical solution provided in this application embodiment, the dovetail 103 in the sealing ring 100 and the dovetail groove 212 on the small spray gun 200 are designed with an interference fit to achieve quick connection and stable fit between the sealing ring 100 and the small spray gun 200, while ensuring the coaxiality of the two, improving the sealing performance of the integrated spray structure, preventing shot splashing, ensuring the safety of the descaling process, ensuring the reliability of the overall structural connection and the stability of the function, and this quick-release design makes the replacement of the sealing ring 100 more convenient, realizing the rapid replacement of vulnerable parts, simplifying equipment maintenance, and reducing the maintenance cost of the integrated spray structure. At the same time, the design of the sealing ring 100 ensures the seal between the spray gun and the nozzle when the spray gun is fired, and ensures that the shot will not scatter in case of accidents; the design of the small spray gun 200 enables high-speed spraying of shot in a limited space, realizing the stability and efficiency of the integrated spray structure under complex working conditions. In addition, by setting the nozzle 211 to a slender tube structure, extending more than 30mm into the heat transfer tube, the influence of the tail airflow on the seal is reduced, ensuring the shot peening effect while preventing shot leakage.

[0027] In at least one embodiment of this application, the width of the dovetail 103 is 0.05~0.2mm larger than the width of the dovetail groove 212. This makes the dovetail 103 and the dovetail groove 212 form an interference fit, fixing the sealing ring 100 to the small spray gun 200 together and preventing it from falling off.

[0028] In at least one embodiment of this application, such as Figure 3As shown, the dovetail 103 has a wedge-shaped protrusion structure. The dovetail groove 212 has a wedge-shaped recess structure. In this way, by setting the wedge-shaped protrusion structure of the dovetail 103 to match the wedge-shaped recess structure of the dovetail groove 212, the sealing ring 100 and the small spray gun 200 are positioned and engaged, preventing axial relative movement.

[0029] In at least one embodiment of this application, the sealing ring 100 further includes a boss 101. The boss 101 is disposed at the front end of the base 102. Thus, the sealing ring 100 achieves the function of preventing foreign objects from entering through the design of the boss 101. When the gas supply is suddenly interrupted during shot peening, the boss 101 can prevent shot from falling to the outside of the pipe opening, while preventing external impurities from entering the interior of the heat transfer tube. Through the elastic deformation of the base 102 of the sealing ring 100 and the insertion design of the small spray gun 200, combined with the foreign object prevention design of the boss 101, the sealing reliability and safety between the spray gun and the heat transfer tube opening are greatly improved.

[0030] In at least one embodiment of this application, the height of the boss 101 is 2mm to 3mm.

[0031] In at least one embodiment of this application, the main body of the small spray gun 200 is made of 3Cr13. This allows the small spray gun 200 to achieve a final hardness of 50 HRC, resulting in strong impact resistance.

[0032] In at least one embodiment of this application, reference is made to Figure 4 The small spray gun 200 includes an inlet section 204, a rectifying section 203, an acceleration section 202, and an ejection section 201, all coaxially aligned. The inlet section 204 is located at the rear end of the small spray gun 200 and is used to introduce a mixture of shot and compressed air. The rectifying section 203 connects the inlet section 204 and the acceleration section 202. The acceleration section 202 connects the rectifying section 203 and the ejection section 201. The ejection section 201 is located at the front end of the small spray gun 200. By maintaining high-precision coaxiality of the inner walls of the inlet section 204, rectifying section 203, acceleration section 202, and ejection section 201, it is ensured that the shot enters the heat transfer tube smoothly, preventing spray deviation.

[0033] In at least one embodiment of this application, the inlet section 204 is a frustum-shaped flow channel, the rectifying section 203 is a cylindrical flow channel, and the acceleration section 202 is an expanding flow channel. Thus, the frustum-shaped flow channel design of the inlet section 204 allows for the introduction of a larger mixture of shot and compressed air. The cylindrical flow channel design of the rectifying section 203 improves flow uniformity. The expanding flow channel of the acceleration section 202 achieves a gradual and stable increase in the velocity of the shot-air mixture through the Venturi effect, ensuring that a preset injection speed is reached at the outlet of the acceleration section 202, thereby comprehensively improving injection efficiency. In this embodiment, by optimizing the internal flow channel design of the small spray gun 200, uniform shot distribution is ensured, improving the descaling effect.

[0034] In at least one embodiment of this application, the expansion angle of the acceleration section 202 is 6° to 10°. This effectively controls the gradual increase in the flow rate of the pellet-air mixture.

[0035] In at least one embodiment of this application, the sealing ring 100 is made of high-hardness nitrile rubber. Thus, the high-hardness nitrile rubber extends the lifespan of the sealing ring 100, exceeding the lifespan of 1000 heat transfer tubes.

[0036] The following describes, with reference to specific embodiments, the installation steps and workflow of an integrated shot peening structure for internal shot peening and descaling of steam generator tube bundles provided in this application.

[0037] Installation steps: Connection of sealing ring 100 and small spray gun 200: Align the dovetail 103 of sealing ring 100 with the dovetail groove 212 of small spray gun 200, and manually apply axial pressure to make dovetail 103 and dovetail groove 212 form an interference fit, thus completing the initial connection between the two; after assembly, check the coaxiality of the two to ensure that there is no misalignment. If the coaxiality does not meet the standard, it is necessary to disassemble and reassemble until the requirements are met.

[0038] External support mechanism connection: Pass the connecting bolts of the external support mechanism 400 through the through hole of the support mechanism and screw them into the mounting internal thread 213 of the small spray gun 200. Use a torque wrench to tighten the bolts to a certain torque to ensure that the small spray gun 200 is stable and does not loosen during operation.

[0039] Pipeline connection: Connect the interface of the shot-compressed air conveying pipeline to the mounting external thread 214 of the small spray gun 200, wrap the thread with polyurethane tape, and then tighten it with a pipe wrench to a certain torque to ensure the connection is sealed and prevent leakage of compressed air and shot.

[0040] Overall inspection: After assembly, perform a visual inspection of the integrated spray structure (no obvious deformation or damage) and a preliminary sealing test (introduce compressed air into the delivery pipeline, apply soapy water to each connection part, and observe whether no bubbles are generated) to ensure that the assembly is qualified.

[0041] Workflow: Positioning and sealing: The integrated spray structure is moved by the external support mechanism 400, so that the nozzle 211 of the small spray gun 200 is aligned with the opening of the heat transfer tube to be descaled, and the nozzle 211 is slowly inserted into the heat transfer tube; the integrated spray structure is continued to be pushed, so that the base 102 of the sealing ring 100 fits against the opening of the heat transfer tube. The pre-tightening force applied by the external support mechanism 400 and the squeezing of the opening of the heat transfer tube cause the base 102 to undergo elastic deformation, forming a tight sealing surface.

[0042] Shot peening descaling operation: Start the shot conveying system and compressed air system. The mixture of shot and compressed air enters through the inlet section 204 of the small spray gun 200 and achieves uniform flow in the rectifier section 203. Then it enters the acceleration section 202 and is accelerated to the predetermined speed under the Venturi effect of the expanding flow channel. Then it is stably conveyed to the nozzle 211 through the ejection section 201 and sprayed at high speed onto the inner wall of the heat transfer tube by the nozzle 211. Post-operation processing: After descaling a single heat transfer tube is completed, first shut down the shot conveying system, and continue to introduce compressed air for a certain period of time to blow the remaining shot in the flow channel of the small spray gun 200 into the heat transfer tube (to be collected uniformly later); then slowly pull out the integrated spray structure through the external support mechanism 400 and move it to the next heat transfer tube to be descaled until all target heat transfer tubes are descaled.

[0043] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0044] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that it includes the explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0045] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An integrated shot structure for internal shot peening of a steam generator tube bundle, comprising: Including sealing rings and small spray guns, The sealing ring includes a base and a dovetail at the rear end of the base; the base is elastic and is used for fitting the heat transfer tube opening; the front end of the small spray gun has a dovetail groove and an internal installation thread, the dovetail and the dovetail groove are interference-fitted, and the internal installation thread is used to connect with the external support mechanism; the external support mechanism is used to ensure the small spray gun is stable and does not loosen during operation; the nozzle of the small spray gun has a slender tube structure, which is used to extend into the heat transfer tube more than 30mm; the rear end of the small spray gun has an external installation thread, which is used to connect with the interface of the shot-compressed air conveying pipeline. The small spray gun includes an inlet section, a rectifier section, an acceleration section, and an ejection section arranged coaxially. The inlet section is located at the rear end of the small spray gun and is used to introduce a mixture of shot and compressed air. The rectifier section is connected between the inlet section and the acceleration section. The acceleration section is connected between the rectifier section and the ejection section. The ejection section is located at the front end of the small spray gun. The inlet section is a frustum-shaped flow channel, the rectification section is a cylindrical flow channel, and the acceleration section is an expanding flow channel; The expansion angle of the acceleration phase is 6°~10°.

2. An integrated jet structure for internal shot peening of steam generator tube bundles as claimed in claim 1, wherein, The width of the dovetail is 0.05~0.2mm wider than the width of the dovetail groove.

3. The integrated shot peening structure for shot peening and descaling inside a steam generator tube bundle according to claim 1, characterized in that, The dovetail has a wedge-shaped protrusion structure, and the dovetail groove has a wedge-shaped groove structure.

4. The integrated shot peening structure for shot peening and descaling inside a steam generator tube bundle according to claim 1, characterized in that, The sealing ring also includes a boss, which is located at the front end of the base.

5. The integrated shot peening structure for shot peening and descaling inside a steam generator tube bundle according to claim 4, characterized in that, The height of the boss is 2mm~3mm.

6. An integrated shot peening structure for shot peening and descaling inside a steam generator tube bundle according to any one of claims 1 to 5, characterized in that, The sealing ring is made of high-hardness nitrile rubber.

7. An integrated shot peening structure for shot peening and descaling inside a steam generator tube bundle according to any one of claims 1 to 5, characterized in that, The main body of the small spray gun is made of 3Cr13.

Images