External penetrating type pulsed eddy current detection device for ultrahigh pressure reaction tube

Abstract

The utility model discloses an external penetrating type pulsed eddy current detection device for an ultrahigh pressure reaction tube. The upper part of a device shell is connected with a holding rod through a connecting seat and a connecting rod, wherein the two ends of the holding rod are provided with holding handles; wheel seats are fixed to the quartering positions of the inner wall of the device shell correspondingly, and rolling wheels are installed on the wheel seats. The excitation coil is rectangular and is composed of a rectangular framework and a magnetic core wrapping the periphery of the rectangular framework. A receiving coil is installed in the center of the exciting coil, and the exciting coil and the receiving coil are both connected with a signal line. The detection device can quickly and continuously penetrate through the ultrahigh pressure reaction tube, the probe part in the detection device can not be in direct contact with the tube wall, mechanical scratches of the outer wall of the ultrahigh pressure reaction tube during detection are avoided, and meanwhile, the wear rate of the probe is reduced. The effective detection depth of the crack defect is improved, and the position of the crack defect can be quickly identified. The device has a series of advantages of high detection sensitivity, large effective crack detection depth, capability of realizing crack defect positioning, small volume, light weight, convenience in carrying and the like.

Description

Technical Field

[0001] The utility model relates to a pulse eddy current nondestructive testing device, which is suitable for nondestructive testing of ultrahigh pressure reaction tubes in LDPE and EVA devices, and particularly relates to an external through-type pulse eddy current testing device for ultrahigh pressure reaction tubes. Background Art

[0002] Ultra-high pressure reaction tube is a common core pressure-bearing equipment in high-pressure polyethylene (LDPE) and ethylene-vinyl acetate resin (EVA) devices. It is different from ordinary industrial pipelines and is often in an environment of high temperature and high pressure, complex corrosion on the outside of the tube, and low-cycle fatigue. At present, the design and manufacture of ultra-high pressure pipelines usually adopt the enterprise standards of patent holders or suppliers, and are divided into grades according to the nominal pressure and nominal diameter of the pipeline; therefore, unlike high, medium and low pressure pipeline systems, ultra-high pressure reaction tubes have relatively few material choices, and usually use ferromagnetic low-alloy seamless thick-walled steel pipes with good toughness and high strength. Ultra-high pressure reaction tubes manufactured at home and abroad are characterized by being thin, long, thick and with cooling water jackets; at the same time, in order to improve the bearing capacity and service life of ultra-high pressure reaction tubes, self-reinforcement treatment technology is widely used in the production and manufacturing process of ultra-high pressure reaction tubes. With the increase of the service life of ultra-high pressure reaction tubes, the self-reinforcement residual stress will relax. When the self-reinforcement residual stress drops to 0, the possibility of cracks in the reaction tube body will greatly increase.

[0003] The operating pressure of the ultra-high pressure reaction tube is generally between 220 and 335 MPa. The design and operating parameters of the ultra-high pressure reaction tubes of some typical million-ton ethylene production enterprises in China are shown in Table 1.

[0004]

[0005] Under normal operating conditions, the ultra-high pressure reaction tube is not only subjected to the high-frequency pressure pulse of the servo pulse valve, but also to the uneven ethylene polymerization reaction in the reaction tube, which causes the ultra-high pressure polyethylene reaction tube to be in a high temperature state with pressure fluctuations for a long time. The resulting fatigue failure will directly cause the relaxation of the self-enhanced residual stress of the ultra-high pressure reaction tube. Once the ultra-high pressure reaction tube body cracks due to fatigue damage, the consequences of leakage and explosion will be unimaginable. In view of this, it is very necessary to conduct non-destructive testing of the ultra-high pressure reaction tube body regularly.

[0006] In the past, the commonly used non-destructive testing methods for the ultra-high pressure reaction tube body included endoscopes and rotating multi-frequency eddy currents. The endoscope can only effectively detect the open macro cracks on the surface of the reaction tube, and the rotating multi-frequency eddy current is generally used for crack detection on the inner surface of the reaction tube. However, for the outer surface of the ultra-high pressure reaction tube, if it is hoped to effectively detect fatigue damage cracks, especially near-surface or sub-surface crack defects, it is necessary to disassemble the outer jacket of the reaction tube and consider using the magnetic particle method or the external through-type multi-frequency eddy current method for crack detection. However, during the on-site operation, it was found that although the magnetic particle detection method can effectively detect the openings, near-surface or sub-surface cracks on the outer wall of the ultra-high pressure reaction tube, the detection efficiency of the magnetic yoke method is very low, and the procedure implemented by the coil winding method is relatively cumbersome. At the same time, the magnetic particle detection requires the application of contrast agent and magnetic suspension, and the outer wall of the reaction tube must be cleaned after each detection, which is time-consuming and labor-intensive. The common external through-type multi-frequency eddy current testing method can only detect the surface open cracks on the outer wall of the reaction tube and the near-surface cracks with a maximum depth of about 2mm, while the detection sensitivity of crack defects at sub-surface depth is very low. Summary of the invention

[0007] In view of the problems existing in the prior art, the utility model provides an external through-type pulsed eddy current testing device for ultra-high pressure reaction tubes, so as to effectively make up for the deficiencies of magnetic particle testing and conventional external through-type multi-frequency eddy current testing technology. It can quickly pass through the outer wall of the ultra-high pressure reaction tube, effectively reduce the probability of mechanical scratches caused by wear between the detection device and the outer wall of the reaction tube while ensuring a sufficient filling factor; achieve full circumferential coverage of the reaction tube body, effectively improve the sensitivity of crack detection, and effectively identify the location of crack defects.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: an external through-type pulse eddy current detection device for an ultra-high pressure reaction tube, comprising a cylindrical device shell, the top of the device shell is connected to a gripping rod with grips at both ends through a connecting seat and a connecting rod; wheel seats are fixed at four equal positions on the inner wall of the device shell, and rollers are installed on the wheel seats; an excitation coil is fixed between two adjacent wheel seats, the excitation coil is rectangular, and consists of a rectangular frame and a magnetic core wrapped around the periphery; a receiving coil is installed at the center position above the excitation coil, and both the excitation coil and the receiving coil are connected to a signal line, the signal line passes through the wiring holes around the device shell and is connected to a signal bus, and the signal bus is connected to a pulse eddy current detection instrument.

[0009] Furthermore, the model of the pulsed eddy current testing instrument is CHPEC-1.

[0010] Furthermore, the excitation coils are located between the front and rear rollers, and there are at least two groups of them.

[0011] Furthermore, the distance between the two groups of excitation coils is 60 mm-100 mm.

[0012] Furthermore, the diameter of the device shell is 90mm-200mm.

[0013] Furthermore, the wheel seat is cylindrical, a compression spring is installed in the cylinder, and the roller is clamped on the compression spring in the cylinder of the wheel seat through a wheel fork.

[0014] Furthermore, the excitation coil and the receiving coil constitute a detection probe, and the axial connection line between the detection probes is parallel to the axis of the cylindrical device shell.

[0015] The utility model can realize fast and continuous penetration of the ultra-high pressure reaction tube, realizes that the probe part in the detection device can avoid direct contact with the tube wall, avoids mechanical scratches on the outer wall of the ultra-high pressure reaction tube during detection, and reduces the wear rate of the probe. It increases the effective detection depth of crack defects and can quickly identify the location of crack defects. It has a series of advantages such as high detection sensitivity, large effective crack detection depth, crack defect positioning, small size and weight, and easy to carry. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0017] Figure 2 This is a front view of the internal structure of the utility model;

[0018] Figure 3 It is a partial cross-sectional schematic diagram of the detection device of the utility model;

[0019] Figure 4 It is a schematic plan view of an absolute probe inside the detection device of the utility model;

[0020] Figure 5 It is a schematic diagram of the cross-sectional structure of the wheel seat of the utility model;

[0021] Figure 6 This is a schematic diagram of the detection application of the utility model;

[0022] In the figure: 01- pulse eddy current testing instrument, 02- signal bus, 03- ultra-high pressure reaction tube; 1- device shell, 11- wiring hole, 12- roller, 13- wheel seat, 14- connecting seat, 15- connecting rod, 16- compression spring, 17- wheel fork; 2- grip rod, 3- handle, 4- excitation coil, 41- magnetic core, 42- skeleton; 5- receiving coil; 6- signal line. DETAILED DESCRIPTION

[0023] The utility model is further described below in conjunction with the accompanying drawings and embodiments. Figures 1 to 5, an external through-type pulse eddy current testing device for ultra-high pressure reaction tubes, comprising a cylindrical device housing 1, the diameter φ of the device housing 1 is 90mm-200mm, a connecting seat 14 is fixed above the device housing 1, a connecting rod 15 is installed on the connecting seat 14, a gripping rod 2 is installed at the top of the connecting rod 15, and gripping handles 3 are installed at both ends of the gripping rod 2 through threads; wheel seats 13 (such as Figure 2 As shown in FIG. 1 ), the wheel seat 13 is cylindrical, and a compression spring 16 is installed in the cylinder. The roller 12 is clamped on the compression spring 16 in the cylinder of the wheel seat 13 through a wheel fork 17 (as shown in FIG. 1 ). Figure 3 As shown in FIG. 1 , a roller 12 is mounted on the wheel seat 13. An excitation coil 4 is fixedly mounted between two adjacent wheel seats 13. The excitation coil 4 is located between the front and rear rollers 12, and there are at least two groups of excitation coils 4. The distance L between the two groups of excitation coils 4 is 60 mm to 100 mm (as shown in FIG. 1 ). Figure 4 The excitation coil 4 is rectangular, and is composed of a rectangular frame 42 and a magnetic core 41 wrapped around the periphery. A receiving coil 5 is installed at the center of the excitation coil 4 (as shown in FIG. Figure 5 As shown in FIG. 1 ), the excitation coil 4 and the receiving coil 5 constitute a detection probe, and the axial connection line between the detection probes is parallel to the axis of the cylindrical device housing 1. The excitation coil 4 and the receiving coil 5 are both connected to the signal line 6, and the signal line 6 passes through the wiring hole 11 around the device housing 1 and is connected to the signal bus 02, and the signal bus 02 is connected to the pulse eddy current detection instrument 01 (as shown in FIG. Figure 1 As shown), the model of pulsed eddy current testing instrument 01 is CHPEC-1. Example

[0024] The utility model is an external through-type pulse eddy current detection device for ultra-high pressure reaction tubes. The overall structure is a cylindrical device shell 1 with a grip rod 2 on the top. The diameter of the device shell 1 is 90mm-200mm (see Figure 2 ). A connection seat 14 is fixedly welded on the outer wall of the device housing 1, and a connection rod 15 is installed in the connection seat 14 for installing the handle 2. Wheel seats 13 are symmetrically welded at four equal positions on the inner wall of the device housing 1. The wheel seat 13 is cylindrical, and a compression spring 16 is installed in the cylinder. The lower end of the compression spring 16 is fixedly connected to the bottom of the cylinder, and the upper end is fixedly connected to the bottom end of the wheel fork 17. The upper end of the wheel fork 17 is an ear fork structure, and a roller 12 is installed in the ear fork.

[0025] Eight absolute pulse eddy current detection probes are evenly arranged and fixed in the cylindrical device housing 1 by welding. The detection probes are composed of an excitation coil 4 and a receiving coil 5 in a rounded rectangular shape. The axial connection between the detection probes is arranged parallel to the axis of the cylindrical device housing 1. The excitation coil 4 is located between the front and rear rollers 12, and there are at least two groups. The distance L between the two groups of excitation coils 4 is 60mm-100mm (see Figure 4). Each probe consists of an excitation coil 4 and a receiving coil 5 in a rounded rectangular shape, wherein the excitation coil 4 is assembled from a magnetic core 41 and a rectangular frame 42. After testing and verification, the length ratio between the magnetic core 41 and the rectangular frame 42 is 3:2, and the width ratio is 4:3; the receiving coil 5 in a rounded rectangular shape is placed at the bottom of the center of the excitation coil 4 and fixed by hot-melt welding. A signal line 6 is used between the excitation coil 4 and the receiving coil 5 for signal excitation and pickup. The outside of the magnetic core 41 is wound with high-quality copper enameled wire with a wire diameter of 0.8mm-1.0mm. The receiving coil 5 uses high-quality copper wire with a wire diameter of 0.21mm-0.32mm. The excitation coil 4 and the receiving coil 5 in a rounded rectangular shape need to be coated with glue for each winding. The signal lines 6 of the eight absolute pulsed eddy current detection probes are connected to the signal bus 02 through eight corresponding circular wiring holes 11 arranged on the outside of the cylindrical device shell 1, and are connected to the pulsed eddy current detection instrument (CHPEC-1 model) 01 through the signal bus 02.

[0026] When the utility model is used, the outer jacket tube of the ultra-high pressure reaction tube 03 to be inspected is firstly disassembled, and the ultra-high pressure reaction tube 03 is placed on a transmission platform or a bracket. The inspector holds the handle 3 in position and controls the eight rollers 12 in the housing 1 of the circular scanner device to achieve supporting contact with the outer surface of the ultra-high pressure reaction tube 03, and the crack defects on the outer wall of the ultra-high pressure reaction tube 03 can be detected by passing through the outer wall of the ultra-high pressure reaction tube 03 (see Figure 1 and Figure 6 ). When using this device, it is necessary to control the overall stepping speed within 300mm / s. At the same time, pay attention to the color change area of ​​the B-scan or C-scan image of the pulsed eddy current array imaging. Once an abnormal signal is found, a magnifying glass or magnetic particle detection or ultrasonic detection should be used to confirm the abnormal signal.

[0027] The model of the pulse eddy current testing instrument 01 in the utility model is: CHPEC-1. The cylindrical device housing 1, the roller 12, the wheel seat 13, the connecting seat 14, the connecting rod 15, and the frame 42 are made of thermoplastic polyester or polycarbonate engineering plastics. The handle 3 is made of wood. The compression spring 16 is made of austenitic stainless steel or aluminum alloy. The magnetic core 41 is made of spinel ferrite material.

[0028] The utility model can realize rapid imaging detection of openings, near-surface or sub-surface crack defects existing in the ultra-high pressure reaction tube 03 in use or under production. Compared with the traditional magnetic particle detection and the conventional external through-type multi-frequency eddy current detection scanning device, it can realize rapid quantitative and positioning detection of sub-surface crack defects with a length of 10mm and a maximum depth of 15mm on the outer wall of the ultra-high pressure reaction tube 03, and improve the detection efficiency by nearly 2 times. At the same time, the utility model has the function of quickly passing through the corrosion pit part, and the pulley structure is used to effectively avoid the direct friction between the probe part and the outer wall body of the ultra-high pressure reaction tube 03, ensuring that the outer wall of the ultra-high pressure reaction tube 03 under inspection will not be mechanically scratched during the inspection operation, and has a series of advantages such as high detection sensitivity, large measurable crack depth, small equipment size and weight, and easy to carry.

Claims

1. An external through-type pulsed eddy current testing device for an ultra-high pressure reaction tube, comprising a cylindrical device housing, characterized in that: The top of the device shell is connected to the grip rods with grips at both ends through a connecting seat and a connecting rod; wheel seats are fixed at four equal positions on the inner wall of the device shell, and rollers are installed on the wheel seats; an excitation coil is fixed between two adjacent wheel seats, and the excitation coil is rectangular and consists of a rectangular frame and a magnetic core wrapped around the periphery; a receiving coil is installed at the center position above the excitation coil, and both the excitation coil and the receiving coil are connected to the signal line, and the signal line passes through the wiring holes around the device shell and is connected to the signal bus, and the signal bus is connected to the pulse eddy current detection instrument.

2. The external through pulse eddy current testing device for ultra-high pressure reaction tube according to claim 1, characterized in that: The model of the pulsed eddy current testing instrument is CHPEC-1.

3. The external through pulse eddy current testing device for ultra-high pressure reaction tube according to claim 1, characterized in that: The excitation coils are located between the front and rear rollers and are at least two groups.

4. The external through-type pulsed eddy current testing device for ultra-high pressure reaction tube according to claim 3, characterized in that: The distance between the two groups of excitation coils is 60mm-100mm.

5. The external through pulse eddy current testing device for ultra-high pressure reaction tube according to claim 1, characterized in that: The diameter of the device shell is 90mm-200mm.

6. The external through pulse eddy current testing device for ultra-high pressure reaction tube according to claim 1, characterized in that: The wheel seat is cylindrical, a compression spring is installed in the cylinder, and the roller is clamped on the compression spring in the cylinder of the wheel seat through a wheel fork.

7. The external through pulse eddy current testing device for ultra-high pressure reaction tube according to claim 1, characterized in that: The excitation coil and the receiving coil constitute a detection probe, and the axial connection line between the detection probes is parallel to the axis of the cylindrical device shell.

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