Preparation method of Venturi tube with wear-resistant surfacing layer on inner wall

Abstract

The invention relates to the technical field of construction of hydrogen-based shaft furnaces, in particular to a preparation method of a Venturi tube with a wear-resistant surfacing layer on the inner wall. Comprising the following steps: determining components contained in the Venturi tube; a surfacing test is conducted, and surfacing welding shrinkage is confirmed; blanking is conducted according to the shrinkage amount of the test; the Venturi tube section is manufactured in a segmented mode; surfacing is conducted in a segmented mode, and size measurement is conducted when the surfacing layer is 100 mm away from a pipe opening; butt welding is carried out, the overall length is measured, and final size fixed-length cutting work is carried out; and flange face welding work is conducted, the flange face and the Venturi tube are welded, and finally forming is conducted. According to the method, the Venturi tube is manufactured in a segmented mode, the surfacing test is conducted firstly to determine the shrinkage amount, then blanking is conducted according to the shrinkage amount, the allowance is reserved, and fixed-length cutting is conducted after surfacing, so that the problem that size deformation cannot be estimated after traditional overall surfacing is effectively solved, the final forming size precision of the Venturi tube is guaranteed, the Venturi tube can meet the design requirement, and the production efficiency is improved. And the venturi effect is normally exerted.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen-based shaft furnace construction, in particular to a manufacturing technology of a venturi tube used in a hydrogen-based shaft furnace, specifically a method for preparing a venturi tube with a wear-resistant surfacing layer on the inner wall. Background Art

[0002] As a fluid measurement and control device based on the Venturi effect, the Venturi tube plays a vital role in fluid measurement. It accelerates the fluid through the structure of the contraction section, throat and diffusion section.

[0003] In the field of hydrogen-based vertical furnaces, the Venturi tube requires a wear-resistant cladding layer on the inside to ensure its performance and lifespan due to the high-speed flow of the internal fluid and the complex working conditions. However, the traditional preparation process has significant drawbacks. Usually, the Venturi tube is manufactured as a whole first, and then the internal cladding is performed. Due to the large amount of heat input generated during the cladding process, the outer shell of the Venturi tube undergoes unpredictable shrinkage deformation in the diameter and length directions. As a result, the overall molding dimensions of the Venturi tube often cannot meet the drawing and design requirements. The dimensional deviation will directly affect the normal functioning of the Venturi effect, reducing production efficiency. It may also cause the Venturi tube to be directly scrapped, resulting in a huge waste of raw materials and manufacturing costs, seriously restricting the stable operation and production efficiency of the hydrogen-based vertical furnace.

[0004] To address the problems of Venturi tube shell deformation and damage caused by operating conditions during use, patent publication number CN103791953A, entitled "High-Precision Integrated Nuclear-Grade Venturi Tube," proposes a solution. This patent document addresses the problem of dimensional deformation during use by modifying the shape of the Venturi tube and the connection structure of certain parts. However, this approach only addresses the problem of Venturi tube deformation from the perspective of structural strength; it does not address the problem of decreased measurement accuracy caused by defects in the weld overlay layer when the Venturi tube has one.

[0005] Although there is some research on Venturi tube cladding technology in the industry, there is no ideal solution to the key problem of how to effectively control the deformation caused by cladding heat input under the specific working conditions of hydrogen-based vertical furnaces to ensure the precise forming size of the Venturi tube.

[0006] Therefore, an innovative preparation method is urgently needed to overcome this technical difficulty and meet the actual needs of hydrogen-based vertical furnaces for high-performance, high-precision Venturi tubes. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above-mentioned defects and propose a high-precision preparation method for a Venturi tube with a wear-resistant hardfacing layer on the inner wall. This method focuses on improving the treatment method of the wear-resistant hardfacing layer inside the Venturi tube so that the Venturi tube prepared by this method meets the use requirements of a hydrogen-based vertical furnace.

[0008] In order to achieve the above object, the present invention is achieved as follows: A method for preparing a venturi tube having an inner wall with a wear-resistant cladding layer comprises the following steps: Step 1: Determine the components of the venturi tube, including the flange surface, straight pipe section, and concentric reducer section; Step 2: Conduct a cladding test to confirm the shrinkage of the cladding, including the shrinkage a% in the diameter direction and the shrinkage b% in the length direction; Step 3: Prepare for cutting according to the shrinkage value of the test. Cut the pipe section: the diameter dimension is the drawing diameter Ød*(1+a%); the cutting length is: drawing length L*(1+b%)+50mm; Step 4: Divide the Venturi tube into sections according to the principle of one straight tube and one reducer, and perform the first welding stage; Step 5: Perform surfacing welding on the second, third and fourth sections in sections, and measure the size when the surfacing layer is 100mm away from the pipe mouth. Cut the second and third sections to the length in the drawing, and do not cut the fourth section to the length for the time being; Step 6: Butt-weld the second, third, and fourth pipe sections to complete the second assembly phase, perform the second surfacing welding, measure the overall length, and perform the final size cutting work at the fourth section; Step 7: Perform flange surface welding work, weld the flange surface to the Venturi tube, and finally form it; in: The thickness of the cladding layer is 3-10 mm to ensure that the inner side of the venturi tube has sufficient wear resistance and avoid excessive shrinkage deformation caused by an overly thick cladding layer; In step 3, during the blanking preparation, the blanking length and the reserved allowance in the diameter direction of the pipe section are calculated based on the shrinkage determined by the cladding test to ensure that the dimensional accuracy of the Venturi tube after cladding is within ±1mm, thereby meeting the design requirements and ensuring the normal functioning of the Venturi effect; In step 3, during the blanking process, the final size cutting work adopts CNC plasma cutting technology, and the cutting accuracy is controlled within ±0.5mm to ensure the final length of the Venturi tube and the accuracy of the dimensions of each part; In step 4, in the segmented production, the welding of each pipe segment adopts full penetration welding, and non-destructive testing is performed after welding to ensure that the welding quality meets the use strength and sealing requirements of the Venturi tube; In step 5, during the first and second cladding welding processes, the cladding heat input is controlled within the range of 10-30 kJ / cm to balance the forming quality and thermal shrinkage of the cladding layer, thereby preventing excessive deformation of the venturi tube due to excessive heat input or weak bonding of the cladding layer due to too low heat input.

[0009] In the above-mentioned method for preparing a Venturi tube having a wear-resistant hardfacing layer on the inner wall, the hardfacing test in step 2 uses a steel plate of the same thickness as the Venturi tube to roll a section of straight seam welded pipe with an outer diameter of 500 mm and a length of 1000 mm for internal hardfacing. The outer diameter and length after hardfacing are measured to determine the shrinkage. The hardfacing test is performed at least three times under the same process conditions as actual production, and the average shrinkage is taken as the final a% and b% values ​​to improve the accuracy and reliability of the shrinkage data.

[0010] The above-mentioned method for preparing a Venturi tube with a wear-resistant cladding layer on the inner wall, the segmented production in step 4 includes dividing the Venturi tube into a first section: a flange surface; a second section: a straight pipe section + a concentric reducer pipe section; a third section: a straight pipe section + a concentric reducer pipe section; and a fourth section: a straight pipe section. When each pipe section is segmented, a 50-100mm cladding buffer zone is reserved at its end to avoid excessive stress concentration and deformation of the cladding layer at the connection between the pipe sections.

[0011] In the above-mentioned method for preparing a Venturi tube having a wear-resistant cladding layer on the inner wall, the dimensional measurement of the cladding layer at a distance of 100 mm from the pipe mouth in step 5 is performed to ensure the dimensional accuracy after cladding, and the pipe section is cut to a fixed length after measurement. The end of the cut pipe section needs to be chamfered with a chamfer angle of 30-45° to facilitate subsequent welding assembly and ensure welding quality.

[0012] In the above-mentioned method for preparing a Venturi tube having a wear-resistant cladding layer on the inner wall, the second cladding welding in step 6 is to clad the connection positions of each pipe section to ensure the continuity and integrity of the cladding layer. In addition, the surface of the cladding layer is monitored and repaired in real time during the cladding process to ensure that the surface flatness of the cladding layer is within ±1 mm, thereby improving the wear resistance of the inner side of the Venturi tube and the uniformity of the fluid flow.

[0013] In the above-mentioned method for preparing a Venturi tube having a wear-resistant cladding layer on its inner wall, the flange surface welding in step 7 adopts full penetration welding to ensure welding quality and connection strength. After welding, the flange surface is fine-machined to achieve a flatness of within 0.1 mm to ensure the sealing and connection reliability of the connection between the Venturi tube and the hydrogen-based vertical furnace.

[0014] The above-mentioned method for preparing a Venturi tube with a wear-resistant cladding layer on the inner wall also includes, after step 7, a heat treatment process for the entire Venturi tube, with a heat treatment temperature range of 600-800°C and a holding time of 1-3 hours, followed by slow cooling to eliminate residual stress generated during welding and cladding, thereby improving the overall stability and service life of the Venturi tube.

[0015] The above-mentioned method for preparing a Venturi tube with a wear-resistant cladding layer on the inner wall also includes, after step 7, a non-destructive testing process for the Venturi tube, using a combination of ultrasonic testing and radiographic testing to comprehensively test the welding parts and cladding layer of the Venturi tube to ensure that there are no defects such as cracks, pores, and slag inclusions. Subsequent installation and use can only be carried out after passing the test.

[0016] The above-mentioned Venturi tube preparation method proposed in the present invention manufactures the Venturi tube in sections, first conducts a surfacing test to determine the shrinkage amount, then reserves a margin for cutting according to the shrinkage amount, and then cuts to a fixed length after surfacing. This effectively solves the problem of unpredictable dimensional deformation after traditional overall surfacing, ensures the final forming dimensional accuracy of the Venturi tube, enables it to meet design requirements, and normally exert the Venturi effect.

[0017] Furthermore, through the above-mentioned technical solution, the present invention achieves process optimization and quality assurance for Venturi tube manufacturing without significantly changing the structure of the Venturi tube or significantly increasing manufacturing costs. Detailed and strict requirements and measures are implemented for each step, from blanking, welding, cladding, cutting, heat treatment, and non-destructive testing. For example, full penetration welding and non-destructive testing are used to ensure weld quality; the cladding heat input range is controlled to balance the build quality of the cladding layer with thermal shrinkage; the heat treatment process eliminates residual stress, improving stability and service life; and non-destructive testing ensures that welds and cladding layers are free of defects. These measures comprehensively guarantee the manufacturing quality and performance of the Venturi tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the venturi tube shown in the present invention. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0020] like Figure 1 The method for preparing a venturi tube having a wear-resistant surfacing layer on the inner wall includes: 1. Surfacing test Based on the Venturi tube design drawings, steel plates of the same thickness as the tube were selected and rolled into straight seam welded pipes with an outer diameter of 500mm and a length of 1000mm to serve as cladding test pieces. Using the same welding parameters and consumables as in the actual cladding process, the inside of the test piece was cladding welded. After cladding was completed, the test piece was allowed to cool naturally to room temperature. The outer diameter and length of the test pipe after cladding were measured using high-precision measuring equipment and compared with the pre-cladding data. The shrinkage in the diameter direction (a%) and length direction (b%) were calculated. To ensure data accuracy, the cladding test was repeated three times using the same process conditions, and the average of the three measurements was used as the final a% and b% values.

[0021] 2. Preparation for cutting Cut the pipe sections according to the Venturi tube design drawing dimensions and the shrinkage values ​​a% and b% determined by the cladding test. The diameter is calculated as follows: Diameter (Ød) * (1 + a%); Length is calculated as follows: Length (L) * (1 + b%) + 50mm. High-precision CNC cutting equipment is used to ensure surface flatness and dimensional accuracy, with cutting accuracy controlled within ±0.5mm to meet subsequent processing requirements.

[0022] 3. Segmented production and first welding The Venturi tube is divided into four sections, constructed using a straight pipe and a reducer. The first section comprises the flange surface; the second section is a combination of a straight section and a concentric reducer; the third section is a combination of a straight section and a concentric reducer; and the fourth section is a straight section. During the segmented fabrication of each section, a 50-100mm weld buffer is reserved at the ends. The components of the second and third sections are assembled using a full-penetration welding process to ensure the weld quality meets the operational strength and sealing requirements of the Venturi tube. After welding, the weld joints undergo non-destructive testing using ultrasonic and radiographic testing to ensure the welds are free of defects such as cracks, porosity, and slag inclusions. Once qualified, the second and third sections are welded.

[0023] 4. First surfacing The second, third, and fourth sections were welded separately. During the welding process, the heat input was strictly controlled within a range of 10-30 kJ / cm to balance the build quality of the weld overlay layer with thermal shrinkage. When the weld overlay layer was 100 mm from the pipe end, welding was paused and the diameter and length of the pipe section were measured using high-precision measuring equipment. Based on the measurement results, the second and third sections were cut to the length specified in the drawing. The ends of the cut sections were chamfered at a chamfer angle of 30-45°. After chamfering, welding was continued until the weld overlay layer reached the designed thickness. Cutting to length was not performed on the fourth section, and welding was continued until the weld overlay layer reached the designed thickness.

[0024] 5. Second butt welding and second surfacing The second, third, and fourth sections were butt-welded to complete the second assembly phase. Full penetration welding was used to ensure weld quality. After completion, the weld joints underwent nondestructive testing using the same testing methods as before. Once qualified, overlay welding was performed at the joints of each pipe section to ensure the continuity and integrity of the overlay layer. During the overlay welding process, heat input was controlled within a range of 10-30 kJ / cm3, and the overlay layer surface was monitored and repaired in real time to ensure surface flatness within ±1 mm.

[0025] 6. Flange surface welding and final forming The first flange section is assembled with the second section using a full-penetration welding process to ensure weld quality and joint strength. After welding, the flange surface is fine-machined to a flatness of less than 0.1mm to ensure a tight seal and connection reliability between the Venturi tube and the hydrogen-based shaft furnace. High-precision measuring equipment is used to measure the overall length and dimensions of the Venturi tube, ensuring dimensional accuracy within ±1mm. Once qualified, the fourth section is cut to final size using CNC plasma cutting technology, achieving a cutting accuracy of less than ±0.5mm, completing the final shape of the Venturi tube.

[0026] 7. Heat treatment and non-destructive testing The formed Venturi tube undergoes heat treatment at a controlled temperature of 600-800°C for 1-3 hours, followed by slow cooling to eliminate residual stresses generated during welding and cladding, thereby improving the tube's overall stability and service life. After heat treatment, the welds and cladding layers are thoroughly inspected using a combination of ultrasonic and radiographic testing to ensure the absence of defects such as cracks, pores, and slag inclusions. Only after passing these tests can the Venturi tube be installed and used.

[0027] In the above-mentioned embodiment, segmented production and a reserved shrinkage allowance effectively address the traditional problem of excessive dimensional deviation in the overall Venturi tube due to heat input from overlay welding, which in turn affects the Venturi effect. By precisely measuring shrinkage during overlay welding tests and using this information for blanking and cutting, a complete closed-loop dimensional control system is established. This ensures the high precision of the final dimensions of the Venturi tube, meeting design requirements, reducing the risk of scrap due to dimensional deviation and saving raw material and manufacturing costs.

[0028] Furthermore, controlling the thickness of the overlay layer within a range of 3-10mm ensures sufficient wear resistance on the inside of the Venturi tube to cope with the high-speed flow and complex operating conditions of the hydrogen-based shaft furnace, while also preventing excessive shrinkage and deformation caused by excessive overlay thickness. During the overlay process, the overlay layer surface is monitored and repaired in real time to ensure surface flatness within ±1mm, improving wear resistance and fluid flow uniformity, thereby extending the service life of the Venturi tube.

[0029] Furthermore, each pipe section is welded using full penetration welding, and non-destructive testing, including ultrasonic and radiographic testing, is performed after welding to ensure that the weld quality meets the operational strength and sealing requirements of the Venturi tube. The flange surface is finely machined after welding to a flatness of within 0.1mm, ensuring the sealing and connection reliability between the Venturi tube and the hydrogen-based shaft furnace.

[0030] Finally, the entire production process of this embodiment is efficient and orderly, with each step seamlessly integrated from the cladding test to the final nondestructive testing, ensuring high-quality production of the Venturi tube. Through advance planning and precise control, the unforeseen thermal shrinkage caused by welding heat input is manageable, significantly improving the product's dimensional control accuracy and ensuring the ultimate performance of the Venturi tube.

[0031] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a venturi tube with a wear-resistant cladding layer on the inner wall, characterized in that: The following steps are involved: Step 1: Determine the components of the venturi tube, including the flange surface, straight pipe section, and concentric reducer section; Step 2: Conduct a cladding test to confirm the shrinkage of the cladding, including the shrinkage a% in the diameter direction and the shrinkage b% in the length direction; Step 3: Prepare for cutting according to the shrinkage value of the test. Cut the pipe section: the diameter dimension is the drawing diameter Ød*(1+a%); the cutting length is: drawing length L*(1+b%)+50mm; Step 4: Divide the Venturi tube into sections according to the principle of one straight tube and one reducer, and perform the first welding stage; Step 5: Perform overlay welding on the second, third and fourth sections in sections, and measure the dimensions when the overlay welding layer is 100mm away from the pipe mouth. Cut the second and third sections to the lengths in the drawing, and do not cut the fourth section to the lengths for the time being. Step 6: Butt-weld the second, third, and fourth pipe sections to complete the second assembly phase, perform the second surfacing welding, measure the overall length, and perform the final size cutting work at the fourth section; Step 7: Perform flange surface welding work, weld the flange surface to the Venturi tube, and finally form it; in: The thickness of the cladding layer is 3-10 mm to ensure that the inner side of the venturi tube has sufficient wear resistance and avoid excessive shrinkage deformation caused by an overly thick cladding layer; In step 3, during the blanking preparation, the blanking length and the reserved allowance in the diameter direction of the pipe section are calculated based on the shrinkage determined by the cladding test to ensure that the dimensional accuracy of the Venturi tube after cladding is within ±1mm, thereby meeting the design requirements and ensuring the normal functioning of the Venturi effect; In step 3, during the blanking process, the final size cutting work adopts CNC plasma cutting technology, and the cutting accuracy is controlled within ±0.5mm to ensure the final length of the Venturi tube and the accuracy of the dimensions of each part; In step 4, in the segmented production, the welding of each pipe segment adopts full penetration welding, and non-destructive testing is performed after welding to ensure that the welding quality meets the use strength and sealing requirements of the Venturi tube; In step 5, during the first and second cladding welding processes, the cladding heat input is controlled within the range of 10-30 kJ / cm to balance the forming quality and thermal shrinkage of the cladding layer, thereby preventing excessive deformation of the venturi tube due to excessive heat input or weak bonding of the cladding layer due to too low heat input.

2. The method for preparing a venturi tube with a wear-resistant surfacing layer on the inner wall according to claim 1, characterized in that: In the surfacing test in step 2, a section of straight seam welded pipe with an outer diameter of 500 mm and a length of 1000 mm is rolled from a steel plate of the same thickness as the venturi tube for internal surfacing. The outer diameter and length after surfacing are measured to determine the shrinkage. The surfacing test is performed at least three times under the same process conditions as actual production, and the average shrinkage is taken as the final a% and b% values ​​to improve the accuracy and reliability of the shrinkage data.

3. The method for preparing a venturi tube with a wear-resistant surfacing layer on the inner wall according to claim 1, characterized in that: The segmented production in step 4 includes dividing the venturi tube into a first segment: a flange surface; The second section: straight pipe section + concentric reducer section; the third section: straight pipe section + concentric reducer section; the fourth section: straight pipe section. When each pipe section is manufactured in sections, a 50-100mm cladding buffer zone is reserved at the end to avoid excessive stress concentration and deformation of the cladding layer at the connection of the pipe sections.

4. The method for preparing a venturi tube with a wear-resistant surfacing layer on the inner wall according to claim 1, characterized in that: The purpose of measuring the size of the cladding layer at a distance of 100 mm from the pipe mouth in step 5 is to ensure the dimensional accuracy after cladding. After the measurement, the pipe section is cut to a fixed length. The end of the cut pipe section needs to be chamfered with a chamfer angle of 30-45° to facilitate subsequent welding and ensure welding quality.

5. The method for preparing a venturi tube with a wear-resistant surfacing layer on the inner wall according to claim 1, characterized in that: The second overlay welding in step 6 is to overlay the connection positions of each pipe section to ensure the continuity and integrity of the overlay layer, and the surface of the overlay layer is monitored and repaired in real time during the overlay welding process to ensure that the surface flatness of the overlay layer is within ±1mm, so as to improve the wear resistance of the inner side of the Venturi tube and the uniformity of the fluid flow.

6. The method for preparing a venturi tube with a wear-resistant cladding layer on the inner wall according to claim 1, characterized in that: The flange surface welding in step 7 is performed by full penetration welding to ensure welding quality and connection strength, and the flange surface is finely processed after welding to make its flatness within 0.1 mm to ensure the sealing and connection reliability of the connection between the venturi tube and the hydrogen-based shaft furnace.

7. The method for preparing a venturi tube with a wear-resistant cladding layer on the inner wall according to claim 1, characterized in that: After step 7, the entire venturi tube is subjected to a heat treatment process at a temperature range of 600-800°C for 1-3 hours, followed by slow cooling to eliminate residual stress generated during welding and surfacing, thereby improving the overall stability and service life of the venturi tube.

8. The method for preparing a venturi tube with a wear-resistant cladding layer on the inner wall according to claim 1, characterized in that: After step 7, a non-destructive testing process is also included for the venturi tube, which uses a combination of ultrasonic testing and radiographic testing to comprehensively test the welding parts and cladding layers of the venturi tube to ensure that there are no defects such as cracks, pores, slag inclusions, etc. The subsequent installation and use can only be carried out after passing the test.

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