A kind of gasifier finned tube fillet weld digital ray detection device and detection method

Abstract

The application provides a kind of gasifier finned tube fillet weld digital ray detection device and detection method, for detecting finned tube fillet weld at finned tube and header welding place.Detection device includes moving guide rail and scanner, utilize moving guide rail to realize multidirectional free movement, the ray emitted by X-ray machine passes through finned tube fillet weld, and utilize digital detector to receive the X-ray that transmits, and then image judges defect condition.Detection method includes the following steps: S1.plate arrangement;S2.transillumination scheme design;S3.sensitivity test block design and verification;S4.scattered ray shielding;S5.transillumination detection;S6.image evaluation.Adopt oblique double-wall source image imaging transillumination scheme, and the upper and lower parts of finned tube fillet weld are respectively transilluminated.Through detection to finned tube fillet weld subarea and the regulation of moving guide rail, effectively solve the problem that the structure of workpiece to be detected is complex, leading to digital ray detection system cannot be arranged, ensure that finned tube fillet weld is irradiated in all directions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a kind of gasifier finned tube fillet digital ray detection device and detection method. BACKGROUND

[0002] Open rack gasifier is one of the core equipment of LNG receiving station, which uses seawater circulation to gasify LNG by temperature difference, and has been widely used in various receiving stations in China. In order to ensure the gasification efficiency, a large number of finned tubes are used for heat exchange, and the finned tubes are connected with the header through welding. Since the finned tubes need to withstand low temperature and high pressure during operation, and the design life is usually about thirty years, high requirements are put forward for the joint quality of finned tube fillet.

[0003] The finned tube and header of open rack gasifier are both made of aluminum alloy, and TIG or MIG welding method is often used, which is prone to defects such as incomplete fusion, porosity and tungsten inclusion. Since the inner and outer walls of the finned tube are both processed with fins or plum blossom grooves, which will interfere with the propagation path of ultrasonic waves, it does not have the basic conditions for ultrasonic detection, and only ray method can be used to detect internal defects. The fillet of finned tube and header is a semi-inserted joint, and the weld reinforcement is very high. When carrying out film method ray detection, there are several problems: first, the thickness variation of the fillet leads to uneven blackness of the negative, affecting the detection sensitivity and leading to insufficient detection ability of small defects; second, due to the small diameter of the header, it is difficult to attach the film, and the distance between the finned tubes is small, which is easy to block each other during ray penetration, resulting in small penetration length and low detection efficiency. Due to the above reasons, there are great difficulties in the quality detection method of finned tube weld of gasifier at present, which cannot meet the actual production needs.

[0004] Digital ray uses digital flat panel detector (DDA) to receive ray, which can directly display the detection results in the form of digital image, and the detection efficiency is very high. Compared with film method ray detection, the dynamic range of digital ray detector is very high, and under the condition of large variation of weld thickness, combined with digital image processing technology, it can still maintain high detection sensitivity, and the detection rate of incomplete fusion and small pores is high. However, since the detector cannot be bent, it is difficult to enter the restricted space, and the detection effect is often affected by the structure of workpiece. Therefore, it also restricts the application of digital ray in the detection of finned tube fillet of open rack gasifier. SUMMARY

[0005] Therefore, the present application aims to provide a kind of gasifier finned tube fillet digital ray detection device and detection method, which can quickly complete the detection of single-row finned tube by using digital imaging plate and automatic scanning detection device, and the detection results are displayed in real time, which can meet the detection requirements of small pores and incomplete fusion, and realize high sensitivity and high efficiency detection of finned tube fillet.

[0006] To achieve the above object, the technical scheme of the present application is as follows:

[0007] In one aspect, the present application provides a kind of gasifier finned tube fillet weld digital ray detection device, for the detection of the workpiece to be detected, the workpiece to be detected includes finned tube and header, the finned tube and header are connected by welding, and the welding place is finned tube fillet weld, the detection device includes moving guide rail and scanner, the moving guide rail includes drive wheel, scanning shaft, left and right positioning shaft, height positioning shaft, up-down turnover shaft and arc wall, and the automatic movement of moving guide rail is realized by software control;The scanner includes X-ray machine and digital detector, the X-ray machine and digital detector are all arranged on arc wall, and the arc wall is circular arc, and the connecting line of X-ray machine and digital detector always passes through the center of arc wall.The distance between X-ray machine and digital detector is unchanged by ensuring that the connection always passes through the center of arc wall, so that the influence of deviation angle can be reduced.

[0008] Further, the up-down turnover shaft is connected by second track and arc wall, one side of the height positioning shaft is connected with the up-down turnover shaft, and the other side is connected by first track and left and right positioning shaft, one side of the scanning shaft is connected with the integrated table and left and right positioning shaft, and the other side is connected with the drive wheel.The positioning accuracy of finned tube fillet weld is realized by the movement in each direction, so that the digital ray can irradiate the finned tube fillet weld of each part of the gasifier.

[0009] Further, the scanning shaft is used to drive the drive wheel to move linearly in the front-back direction, so that the whole detection device moves linearly in the front-back direction;The left and right positioning shaft is used to drive the arc wall to move linearly along the integrated table in the left-right direction, the height positioning shaft is used to drive the arc wall to move linearly along the first track in the up-down direction, the up-down turnover shaft is used to drive the arc wall to turn in the front-back direction, and the arc wall is used to rotate in the plane formed by x axis and y axis.

[0010] In another aspect, the present application provides a kind of gasifier finned tube fillet weld digital ray detection method, the detection method uses the detection device described above, for detecting finned tube fillet weld, the detection method uses inclined double-wall source side imaging transmission scheme, and the upper and lower parts of finned tube fillet weld are respectively transmitted and projected on digital imaging plate.

[0011] Further, the detection method includes the following steps:

[0012] S1. a plurality of finned tubes and header plates are kept in flat state;

[0013] S2. transmission scheme design;

[0014] S3. sensitivity test block design and verification;

[0015] S4. Scatter shield;

[0016] S5. Radiographic inspection;

[0017] S6. Image evaluation.

[0018] Further, the step S5 comprises the following steps:

[0019] S51. Adjusting the scanning axis, the left-right positioning axis, the height positioning axis, the up-down flipping axis and the arc-shaped wall, so that the upper side of the finned tube fillet weld is located in the radiographic area, and the X-ray machine emits a ray beam which passes through the double-layer wall thickness of the finned tube fillet weld and the header located at the upper side and is projected on the digital detector;

[0020] S52. Adjusting the scanning axis to drive the detection device to move back and forth along the arrangement direction of the plurality of headers, so as to perform segmented scanning detection on the upper side of the plurality of finned tube fillet welds and obtain corresponding detection images;

[0021] S53. Adjusting the up-down flipping axis to flip the arc-shaped wall, so that the lower side of the finned tube fillet weld is located in the radiographic area, and the X-ray machine emits a ray beam which passes through the double-layer wall thickness of the finned tube fillet weld and the header located at the lower side and is projected on the digital detector;

[0022] S54. Adjusting the scanning axis to drive the detection device to move back and forth along the arrangement direction of the plurality of headers, so as to perform segmented scanning detection on the lower side of the plurality of finned tube fillet welds and obtain corresponding detection images.

[0023] Further, the radiographic area in the steps S51 and S53 refers to that the line connecting the X-ray machine and the digital detector passes through the center of the header, and the included angle α formed between the line and the x-axis is 0-20°.

[0024] Further, in the step S5, when the upper and lower parts of the finned tube fillet weld are radiographed respectively, the fillet weld area radiographed each time is 200°-360°. This ensures that the radiographed range covers the outer periphery of the finned tube fillet weld when radiographing the upper and lower parts.

[0025] Further, in the step S3, the sensitivity of the detection is verified by a sensitivity test block. The sensitivity test block is in a circular ring structure and has through holes arranged at 0°, 90°, 180° and 270° positions respectively. When the images of not less than 3 through holes can be clearly observed, it is indicated that the sensitivity requirement is met.

[0026] Further, in the step S4, the scattered ray shielding is divided into three parts: the first part is a side reflection shielding scheme, lead sheet is laid on the outer periphery of the finned tube on the same side as the finned tube corner weld to be detected; the second part is a transmission surface scattering shielding scheme, lead sheet is arranged around the header, and the lead sheet cannot cover the finned tube corner weld; and the third part is a header internal scattering shielding, lead sheet is laid in the header. Through the scattered ray shielding scheme, lead sheet is laid on the places other than the finned tube corner weld of the workpiece to be detected, the reflection and scattering interference of other parts is reduced, and the detection sensitivity and image clarity are improved.

[0027] Compared with the prior art, the gasifier finned tube corner weld digital ray detection device and detection method has the following advantages:

[0028] (1) A double-wall source side imaging transmission scheme is determined, that is, the finned tube corner weld is arranged on the ray source side imaging according to the characteristics of the workpiece to be detected, the problem that the digital ray detection system of the complex welded joint is difficult to arrange is solved, and the finned tube corner weld is ensured to be irradiated in all directions;

[0029] (2) A special sensitivity test block is designed to ensure the detection sensitivity, and a special scattered ray shielding scheme is set according to the structure characteristics of the workpiece to reduce the scattering interference, and the image quality is greatly improved.

[0030] (3) An automatic detection device is used for detection, the stability of the detection process is ensured, the process specification is easier to control, and the detection efficiency is also greatly improved;

[0031] (4) The maximum transmission thickness can reach 70 mm, and the defects such as pores, incomplete fusion, cracks, tungsten inclusions and copper inclusions at the finned tube corner weld can be effectively detected, the relative sensitivity is better than 2%, and the detection efficiency is improved by 200%;

[0032] (5) The digital imaging plate is used instead of the film, the image tolerance is improved, the detection sensitivity is maintained under the condition of the finned tube corner weld with different thicknesses, and the defect detection rate is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] It should be noted that the terms "upper", "lower", "left", "right", "front", "back", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0034] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The illustrations are given for the purpose of explaining the application and do not constitute an improper limitation on the application. In the drawings:

[0035] Figure 1 Structure diagram of the finned tube, header and finned tube fillet of the present application;

[0036] Figure 2 Structure diagram of the right view of the present application; Figure 1

[0037] Figure 3 Structure diagram of the detection device of the present application;

[0038] Figure 4 Structure diagram of the sensitivity test block of the present application;

[0039] Figure 5 Verification result diagram of the sensitivity test block of the present application;

[0040] Figure 6 Scatter shield diagram of the present application;

[0041] Figure 7 Structure diagram of the header, finned tube fillet and lead sheet of the present application;

[0042] Figure 8 Structure diagram of the finned tube fillet on the upper side of the present application;

[0043] Figure 9 Structure diagram of the finned tube fillet on the lower side of the present application;

[0044] Figure 10 Detection image of the finned tube fillet of Example 1 of the present application.

[0045] Explanation of the reference signs:

[0046] 1. Finned tube; 2. Header; 3. Finned tube fillet; 4. Driving wheel; 5. Scanning shaft; 6. Integrated table; 7. Left-right positioning shaft; 8. Height positioning shaft; 9. Up-down overturning shaft; 10. Arc-shaped wall; 11. X-ray machine; 12. Digital detector; 13. PVC tube; 14. Lead sheet; 17. Sensitivity test block; 18. Through hole; 19. First track; 20. Second track. DETAILED DESCRIPTION

[0047] ​The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0048] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0049] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0050] The vaporizer utilizes the temperature difference from the circulating seawater to vaporize LNG. For example... Figures 1-2 As shown, vaporizers typically employ numerous finned tubes 1 for heat exchange, with multiple finned tubes 1 connected together via manifolds 2. The finned tubes 1 and manifolds 2 are welded together, forming a fillet weld 3. Defects such as incomplete fusion, porosity, and tungsten inclusions are prone to occur at the fillet weld 3, thus affecting the vaporizer's airtightness. Therefore, this invention proposes a digital X-ray inspection device for the fillet weld of vaporizer finned tubes, used to inspect the welding condition of the fillet weld 3. The finned tubes 1, manifolds 2, and fillet weld 3 constitute the workpiece to be inspected.

[0051] like Figure 3 As shown, the detection device includes a moving guide rail and a scanner, with the scanner positioned on the moving guide rail. For ease of description, under normal use and placement conditions of the detection device, as... Figure 3 As shown, in the horizontal direction, one side of the detection device is defined as the left side, and the other side is defined as the right side. That is... Figure 3 The direction of the x-axis. In the height direction, one side of the detection device is defined as the upper side, and the other side is defined as the lower side, i.e. Figure 3 The direction of the y-axis. In the direction perpendicular to the paper, the side of the detection device facing the paper is defined as the rear side, and the side of the detection device away from the paper is defined as the front side, i.e. Figure 3 The direction of the z-axis.

[0052] The moving guide rail comprises a driving wheel 4, a scanning shaft 5, a left-right positioning shaft 7, a height positioning shaft 8, an up-down overturning shaft 9 and an arc wall 10. The scanning shaft 5, the left-right positioning shaft 7, the height positioning shaft 8, the up-down overturning shaft 9 and the arc wall 10 are all controlled by motors and automatically moved by software control, with a positioning accuracy of ±2mm. Since the moving guide rail is automatically moved by software control, which is the prior art, no further description is given herein. The positioning accuracy of the finned tube fillet weld 3 is realized by movement in various directions, thereby ensuring that the digital rays can irradiate the finned tube fillet weld 3 everywhere in the gasifier.

[0053] The scanner comprises an X-ray machine 11 and a digital detector 12, both of which are arranged on the arc wall 10, and the arc wall 10 is in the shape of a circular arc, with the line connecting the X-ray machine 11 and the digital detector 12 always passing through the center of the arc wall 10. The rays emitted by the X-ray machine 11 pass through the finned tube fillet weld 3 and feed back the detection condition to the digital detector 12. When the detection device of the present application is used for detection, the rays emitted by the X-ray machine 11 are perpendicular to the surface of the digital detector 12, so that the reflection condition of the rays is imaged on the digital detector 12. Only when the connection between the X-ray machine 11 and the digital detector 12 always passes through the center of the arc wall 10 and the distance between them is constant, can the influence of the deviation angle be reduced. Specifically, in order to ensure that the line connecting the X-ray machine 11 and the digital detector 12 always passes through the center of the arc wall 10 during movement, the corresponding arc angle of the arc wall 10 is 240°-360°, and the line connecting the X-ray machine 11 and the digital detector 12 forms the diameter of the circle on which the arc wall 10 is located.

[0054] The up-down overturning shaft 9 is connected with the arc wall 10 through a second track 20, one side of the height positioning shaft 8 is connected with the up-down overturning shaft 9, and the other side is connected with the left-right positioning shaft 7 through a first track 19, one side of the scanning shaft 5 is connected with the left-right positioning shaft 7 through an integrated table 6, and the other side is connected with the driving wheel 4. The scanning shaft 5 is used to drive the driving wheel 4 to move linearly in the front-back direction, so that the entire detection device moves linearly in the front-back direction to realize segmented movement and complete detection of all the finned tube fillet welds 3; the left-right positioning shaft 7 is used to drive the arc wall 10 to move linearly in the left-right direction along the integrated table 6; the height positioning shaft 8 is used to drive the arc wall 10 to move linearly in the up-down direction along the first track 19; the up-down overturning shaft 9 is used to drive the arc wall 10 to overturn in the front-back direction; and the arc wall 10 is used to rotate in the plane formed by the x-axis and the y-axis.

[0055] Further, the moving stroke of the scanning shaft 5 is not less than 8000 mm, the moving stroke of the left-right positioning shaft 7 is not less than 500 mm, the moving stroke of the height positioning shaft 8 is not less than 2000 mm, and the turning angle of the up-down turning shaft 9 is 200°-360°. This can ensure that the detection device can complete the detection of the finned tube fillet weld 3 formed by the plurality of finned tubes 1 at one time.

[0056] Further, the diameter of the arc-shaped wall 10 is not less than 6 times the outer diameter of the header 2, so as to ensure that the finned tube 1 to be detected and the header 2 can be placed in the arc-shaped wall 10, and the digital X-ray emitted by the X-ray machine 11 can be fully penetrated to the finned tube fillet weld 3.

[0057] The X-ray machine 11 in the application is a high-frequency constant-voltage portable X-ray machine, the maximum tube voltage is not less than 200 kV, the single continuous exposure time is not less than 20 min, the focal point size is not less than 1 mm, and the pixel size of the digital detector 12 is not greater than 147 μm.

[0058] The application further provides a digital X-ray detection method for the finned tube fillet weld of a gasifier, which uses the detection device, adopts an inclined double-wall source imaging penetration scheme, penetrates the upper and lower parts of the finned tube fillet weld 3 respectively, and projects on a digital imaging plate. The plane formed by the x-axis and the y-axis is used as a reference to divide the finned tube fillet weld 3 into upper and lower parts. Since the digital X-ray emitted by the X-ray machine 11 cannot be bent, the workpiece to be detected is adjusted to be placed horizontally, that is, the plurality of finned tubes 1 are placed in sequence in the front-to-back direction. The finned tube fillet weld 3 is divided into upper and lower parts, and the scanning shaft 5, the left-right positioning shaft 7, the height positioning shaft 8, the up-down turning shaft 9 and the arc-shaped wall 10 are moved to make the X-ray machine 11 have a suitable penetration position and penetration angle, so as to penetrate the finned tube fillet weld 3 on the upper side and the finned tube fillet weld 3 on the lower side respectively, and complete the detection of the whole weld. The inclined double-wall source imaging penetration refers to that the X-ray is inclined to irradiate from the same side of the finned tube fillet weld 3.

[0059] Specifically, the digital X-ray detection method for the finned tube fillet weld of the gasifier comprises the following steps:

[0060] S1. The plate formed by the plurality of finned tubes 1 and the header 2 is kept in a horizontal state.

[0061] Specifically, when the plate is kept in the horizontal state, the plurality of finned tubes 1 are placed in sequence in the front-to-back direction. The digital X-ray detection for the finned tube fillet weld of the gasifier is debugged, and after the debugging is completed, the subsequent operation is performed.

[0062] S2. Penetration scheme design.

[0063] Specifically, the penetration imaging is performed in a manner of superimposing multiple frames, and the single frame sampling time and the superimposed frame number are required to ensure that the image gray scale and the normalized signal-to-noise ratio are within an ideal range. The image gray scale and the normalized signal-to-noise ratio within the ideal range refer to that the image gray scale is within 30%-60% of the full range, and the normalized signal-to-noise ratio is not less than 120.

[0064] S3. Sensitivity test block design and verification;

[0065] Specifically, as shown in Figure 4 , the sensitivity of the detection is verified by designing a special sensitivity test block 17. The sensitivity test block 17 is a circular ring structure, and through holes 18 are arranged at positions of 0°, 90°, 180° and 270°, respectively. The material of the sensitivity test block 17 is aluminum. The size of the sensitivity test block 17 and the through hole 18 is not limited here. Further, the diameter of the through hole 18 is 2 mm. The inner diameter of the circular ring of the sensitivity test block 17 is equal to the outer diameter of the finned tube 1, and the thickness of the sensitivity test block 17 is 2% of the double wall thickness of the header 2.

[0066] The sensitivity test block 17 is attached to the outside of the header 2, and the placement position of the sensitivity test block 17 is close to the position of the finned tube fillet weld 3. The sensitivity test block 17 is bent into an arc shape, and the arc curvature matches the header 2, so that the sensitivity test block 17 is easily attached to the outer wall of the header 2. The penetration conditions used in the sensitivity verification are the same as in step S2, and whether the sensitivity meets the requirements is determined.

[0067] As shown in Figure 5 , when the images of not less than 3 through holes 18 can be clearly observed, it is indicated that the sensitivity requirement is met.

[0068] S4. Scatter line shielding;

[0069] Specifically, the scatter line shielding is divided into the following three parts: the first part is a side reflection shielding scheme, lead sheet 14 is laid on the outer periphery of the finned tube 1 on the same side as the finned tube fillet weld 3 to be detected, which is used to shield the scatter lines of the finned tube 1. For example, when the upper side of the finned tube fillet weld 3 is detected by penetration, the lead sheet 14 is laid on the outer periphery of the finned tube 1 on the upper side. When the lower side of the finned tube fillet weld 3 is detected by penetration, the lead sheet 14 is laid on the outer periphery of the finned tube 1 on the lower side. The second part is a penetration surface scattering shielding scheme, lead sheet 14 is arranged around the header 2, and the lead sheet 14 cannot cover the finned tube fillet weld 3, so as to reduce the penetration field area of the digital ray directly entering the inside of the workpiece to be detected. The third part is the internal scattering shielding of the header 2, lead sheet 14 is laid in the header 2 to block the scatter lines from the side of the header 2.

[0070] The lead sheet 14 is laid on the workpiece to be inspected except the finned tube fillet weld 3 by the scattered ray shielding scheme, the reflection and scattering interference of other parts are reduced, and the detection sensitivity and image clarity are improved.

[0071] In the first part of the side reflection shielding scheme, the thickness of the lead sheet 14 laid on the outer periphery of the finned tube 1 is not less than 2mm, and the laying range should be extended from the finned tube fillet weld 3 to the position directly below the X-ray machine 11. In the second part of the scattered ray shielding scheme, two arc-shaped lead sheets 14 are used, the thickness of the lead sheet 14 is not less than 2mm, and one of the lead sheets 14 covers the upper side of the header 2, and the other covers the lower side of the header 2, as shown in Figures 6-7 In the third part of the scattered ray shielding scheme, a PVC pipe 13 with an outer diameter close to the inner diameter of the header 2 is used as a support, and a lead sheet 14 is pasted inside the header 2, the thickness of the lead sheet 14 is not less than 1mm, and the pasting range of the lead sheet 14 cannot affect the projection area of the finned tube fillet weld 3.

[0072] S5. Radiographic detection;

[0073] Specifically, the radiographic detection of step S5 uses the same radiographic conditions as step S2.

[0074] S51. The scanning shaft 5, the left-right positioning shaft 7, the height positioning shaft 8, the up-down flipping shaft 9 and the arc-shaped wall 10 are controlled in a remote driving manner, as shown in Figure 8 The upper side of the finned tube fillet weld 3 is located in the radiographic area. The ray beam emitted by the X-ray machine 11 penetrates the double-layer wall thickness of the finned tube fillet weld 3 and the header 2 on the upper side and is projected on the digital detector 12.

[0075] S52. The scanning shaft 5 is controlled in a remote driving manner, and the detection device is driven to move forward and backward along the arrangement direction of the plurality of headers 2 to segmentally scan and detect the upper sides of the plurality of finned tube fillet welds 3, and corresponding detection images are obtained.

[0076] S53. The up-down flipping shaft 9 is controlled in a remote driving manner to flip the arc-shaped wall 10, as shown in Figure 9 The lower side of the finned tube fillet weld 3 is located in the radiographic area. The ray beam emitted by the X-ray machine 11 penetrates the double-layer wall thickness of the finned tube fillet weld 3 and the header 2 on the lower side and is projected on the digital detector 12.

[0077] S54. The scanning shaft 5 is controlled in a remote driving manner, and the detection device is driven to move back and forth along the arrangement direction of the plurality of headers 2 to segmentally scan and detect the lower side of the fin tube fillet weld 3, and corresponding detection images are obtained.

[0078] Further, when the upper and lower parts of the fin tube fillet weld 3 are penetrated respectively, the fillet weld area penetrated each time is 200°-360°, so as to ensure that the range penetrated when the upper and lower parts are penetrated covers the outer periphery of the fin tube fillet weld 3.

[0079] Further, the penetration area in the step S51 and the step S53 refers to that the line connecting the X-ray machine 11 and the digital detector 12 passes through the center of the header 2, and the included angle a formed between the line and the x axis is 0-20°. The center refers to the center of the header 2 close to the digital detector 12.

[0080] S6. Image evaluation.

[0081] Specifically, after the scanning and detection are completed, the images collected by the digital detector 12 are evaluated. When the images are evaluated, image increasing and other means can be used for auxiliary processing of the images. After the defects are identified, the properties of the defects are determined and the defect lengths are measured. The image evaluation method is prior art, and will not be described in detail here.

[0082] Compared with the prior art, the fin tube fillet weld digital radiographic detection device and detection method of the gasifier of the present application has the following advantages: (1) the automatic detection device is used for detection, which ensures the stability of the detection process, the process specification is easier to control, and the detection efficiency is also greatly improved; (2) by detecting the fin tube fillet weld 3 in sections and controlling the moving guide rail, the problem that the digital ray cannot enter each part of the workpiece to be detected is effectively solved, and the fin tube fillet weld 3 is ensured to be irradiated in all directions; (3) the maximum penetration thickness can reach 70 mm, which can effectively detect defects such as pores, incomplete fusion, cracks, tungsten inclusions and copper inclusions at the fin tube fillet weld 3, and the relative sensitivity is better than 2%, and the detection efficiency is improved by 200%; (4) the digital imaging plate is used instead of the film, which improves the image tolerance, maintains a high detection sensitivity under the condition of the fin tube fillet weld 3 with different thicknesses, and greatly improves the defect detection rate; and the digital image reduces the process processing link of the radiographic detection, avoids the use of film, developer and other consumables, reduces the cost, and reduces environmental pollution; the digital image is convenient to store and share, and can be processed twice by using image processing means, which lays a foundation for intelligent identification of the fin tube fillet weld 3 with defects.

[0083] Example 1

[0084] The present embodiment relates to a kind of gasifier finned tube fillet digital ray detection device and detection method.In the workpiece to be detected, the specification of finned tube 1 is 40mm in outer diameter, and the specification of header 2 is 165x25mm.The arc wall 10 of the detection device is a circular arc with a diameter of 1.1m, and the X-ray machine 11 and the digital detector 12 are arranged on the arc wall 10, and the X-ray machine 11 and the digital detector 12 are separated by 180°.The line connecting the X-ray machine 11 and the digital detector 12 is the diameter of the arc wall 10, and the plane of the digital detector 12 is perpendicular to the diameter.The included angle α formed by the line connecting the X-ray machine 11 and the digital detector 12 and the x-axis is 18°.The X-ray machine 11 uses YXLON EVO 160D, with a maximum tube voltage of 160kV, a continuous exposure time of 60min, and a focal point size of 1mm.The imaging size of the digital detector 12 is 430mmx430mm, the maximum withstand voltage is 400kV, and the pixel size is 145μm.

[0085] A special sensitivity test block 17 is designed, which has a circular ring structure, an inner diameter of 40mm, a difference between the outer circle and the inner circle of 10mm, and a thickness of 1mm.The sensitivity test block 17 is provided with through holes 18 with a diameter of 2mm at positions of 0°, 90°, 180° and 270°.Before detection, the sensitivity test block 17 is attached to the header 2, and the sensitivity is verified by transmission, and at least 3 through holes 18 are clearly visible, and the sensitivity meets the requirements.

[0086] Lead sheet 14 is laid on the outer side of the finned tube 1 on the same side as the X-ray machine 11, for shielding the surface of the finned tube 1 from scattered rays, and the thickness of the lead sheet 14 is 2.5mm and the length is 1m.In the extension direction of the length of the finned tube 1, the length of the lead sheet 14 laid on the outer side of the finned tube 1 exceeds the head of the X-ray machine 11.

[0087] A blocking lead sheet 14 is provided on the transmission surface of the header 2, with a thickness of 2mm, and the lead sheet 14 is composed of two parts, the edge shape is matched with the finned tube fillet 3, and the non-welded area around the finned tube fillet 3 can be effectively covered.A PVC pipe 13 with an outer diameter of 108mm is placed inside the header 2, and an arc-shaped lead sheet 14 with a thickness of 1mm is attached to the outside of the PVC pipe 13, and the projection area of the rays in the uncovered area of the lead sheet 14.

[0088] The position of the workpiece to be detected and the arc wall 10 are adjusted, the transmission focal length is set to 0.9m, the distance between the digital detector 12 and the header 2 is 5mm, and the transmission length is set to 350mm.The transmission parameters are confirmed by test, the transmission voltage is 140kV, the tube voltage is 3mA, the imaging is performed in the mode of 8-frame superposition, the single-frame sampling time is 500mS, the image gray scale is 50% of full scale, and the normalized signal-to-noise ratio is not less than 150.

[0089] The scanning shaft 5, the left-right positioning shaft 7, the height positioning shaft 8, the up-down turning shaft 9 and the arc wall 10 are controlled by remote driving, so that the upper side of the finned tube fillet weld 3 is located in the transmission area. The ray beam emitted by the X-ray machine 11 penetrates the double-layer wall thickness of the finned tube fillet weld 3 and the header 2 located at the upper side, and is projected on the digital detector 12.

[0090] The scanning shaft 5 is controlled by remote driving, and the driving device moves forward and backward along the arrangement direction of the plurality of headers 2, so that the upper side of the plurality of finned tube fillet welds 3 is detected in sections, each section has a detection length of 350 mm, and corresponding detection images are acquired.

[0091] The up-down turning shaft 9 is controlled by remote driving, so that the arc wall 10 is turned, and the lower side of the finned tube fillet weld 3 is located in the transmission area. The ray beam emitted by the X-ray machine 11 penetrates the double-layer wall thickness of the finned tube fillet weld 3 and the header 2 located at the lower side, and is projected on the digital detector 12.

[0092] The scanning shaft 5 is controlled by remote driving, and the driving device moves forward and backward along the arrangement direction of the plurality of headers 2, so that the lower side of the plurality of finned tube fillet welds 3 is detected in sections, each section has a detection length of 350 mm, and corresponding detection images are acquired.

[0093] After the scanning detection is completed, the acquired images are evaluated, as shown in Figure 10 When the images are evaluated, the images can be processed by means such as image addition. The defects are mainly pores, and the diameter is not more than 2 mm, and the evaluation is qualified.

[0094] The above only describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for digital radiographic testing of finned tube fillet welds of a gasifier, using a testing device to test a workpiece to be tested, the workpiece to be tested comprising a finned tube (1) and a header (2), the finned tube (1) and the header (2) being connected by welding, the welded joint being a finned tube fillet weld (3), characterized in that, The detection device comprises a moving guide rail and a scanner, the moving guide rail comprises a driving wheel (4), a scanning shaft (5), a left-right positioning shaft (7), a height positioning shaft (8), an up-down overturning shaft (9) and an arc wall (10), and automatic movement of the moving guide rail is realized through software control; the scanner comprises an X-ray machine (11) and a digital detector (12), the X-ray machine (11) and the digital detector (12) are both arranged on the arc wall (10), and the arc wall (10) is in the shape of a circular arc, and the line connecting the X-ray machine (11) and the digital detector (12) always passes through the center of the arc wall (10); The detection method adopts an inclined double-wall imaging transmission scheme, respectively transmits the upper and lower parts of the finned tube fillet weld (3), and projects on a digital imaging plate, comprising the following steps: S1. A plurality of finned tubes (1) and a header (2) are kept in a flat state; S2. Transmission scheme design; S3. Sensitivity test block (17) design and verification; S4. Scatter shielding; S5. Transmission detection; S51. The scanning shaft (5), the left-right positioning shaft (7), the height positioning shaft (8), the up-down overturning shaft (9) and the arc wall (10) are controlled, so that the upper side of the finned tube fillet weld (3) is located in the transmission area, and the ray beam emitted by the X-ray machine (11) passes through the double-layer wall thickness of the finned tube fillet weld (3) and the header (2) on the upper side and is projected on the digital detector (12); S52. The scanning shaft (5) is controlled to drive the detection device to move back and forth along the arrangement direction of the plurality of headers (2) to segmentally scan and detect the upper side of the plurality of finned tube fillet welds (3) and obtain corresponding detection images; S53. The up-down overturning shaft (9) is controlled to overturn the arc wall (10) to make the lower side of the finned tube fillet weld (3) located in the transmission area, and the ray beam emitted by the X-ray machine (11) passes through the double-layer wall thickness of the finned tube fillet weld (3) and the header (2) on the lower side and is projected on the digital detector (12); S54. The scanning shaft (5) is controlled to drive the detection device to move back and forth along the arrangement direction of the plurality of headers (2) to segmentally scan and detect the lower side of the plurality of finned tube fillet welds (3) and obtain corresponding detection images; S6. Image evaluation.

2. The detection method according to claim 1, characterized in that, The up-down overturning shaft (9) is connected with the arc wall (10) through a second track (20), one side of the height positioning shaft (8) is connected with the up-down overturning shaft (9), the other side is connected with the left-right positioning shaft (7) through a first track (19), one side of the scanning shaft (5) is connected with the left-right positioning shaft (7) through an integrated table (6), and the other side is connected with the driving wheel (4).

3. The detection method according to claim 2, characterized in that, The scanning shaft (5) is used to drive the driving wheel (4) to move linearly in the front-back direction, so as to make the whole detection device move linearly in the front-back direction; the left-right positioning shaft (7) is used to drive the arc-shaped wall (10) to move linearly in the left-right direction along the integrated table (6), the height positioning shaft (8) is used to drive the arc-shaped wall (10) to move linearly in the up-down direction along the first track (19), the up-down overturning shaft (9) is used to drive the arc-shaped wall (10) to overturn in the front-back direction, and the arc-shaped wall (10) is used to rotate in the plane formed by the x-axis and the y-axis.

4. The method of claim 1, wherein The transillumination area in the steps S51 and S53 refers to that the line connecting the X-ray machine (11) and the digital detector (12) passes through the center of the header (2), and the included angle α formed by the line and the x-axis is 0-20°.

5. The method of claim 1, wherein When the upper and lower parts of the finned tube fillet (3) are respectively transilluminated, the fillet area of each transillumination is 200-360°.

6. The method of claim 1, wherein, In the step S3, the sensitivity of the detection is verified by using the sensitivity test block (17), the sensitivity test block (17) is in a circular ring structure, and through holes (18) are arranged at positions of 0°, 90°, 180° and 270°, when the images of not less than three through holes (18) can be clearly observed, it is indicated that the sensitivity requirement is met.

7. The method of claim 1, wherein, In the step S4, the scattered line shielding is divided into three parts: the first part is a side reflection shielding scheme, lead sheets (14) are laid on the outer periphery of the finned tube (1) on the same side as the finned tube fillet (3) to be detected; the second part is a transillumination surface scattering shielding scheme, lead sheets (14) are arranged around the header (2), and the lead sheets (14) cannot cover the finned tube fillet (3); and the third part is a header (2) internal scattering shielding, lead sheets (14) are laid inside the header (2).

Images