Design method of wireless passive electromagnetic ultrasonic detection system for oil and gas pipeline

Abstract

The invention belongs to the technical field of nondestructive testing of oil and gas pipelines, and particularly relates to a design method of a wireless passive electromagnetic ultrasonic testing system for an oil and gas pipeline. According to the design method, the mapping impedance between the coils is directly coupled into a corresponding circuit by utilizing a mutual inductance effect, and all electrical parameters in an electromagnetic ultrasonic detection system do not need to be quantized. Meanwhile, according to different circuit characteristics of an excitation stage and a receiving stage of the wireless passive electromagnetic ultrasonic detection system, resonant capacitance parameters are independently calculated and optimized, so that the transduction efficiency of the wireless passive electromagnetic ultrasonic detection system is remarkably improved, and the signal-to-noise ratio of signals is improved. The design method comprises the following steps: drawing equivalent circuit diagrams of an excitation stage and a receiving stage of the wireless passive electromagnetic ultrasonic detection system; determining a resonance circuit of a host receiving end; determining a resonance circuit of the transducer unit in the excitation stage; determining a resonance circuit of a host excitation end in a receiving stage; a resonant circuit of the transducer unit is determined.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas pipeline nondestructive testing, and particularly relates to a design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines. BACKGROUND

[0002] During the service of petrochemical equipment, fixed-point thickness monitoring is crucial to the safety and reliability of devices such as storage tanks and pipelines. Among them, oil and gas pipelines, pressure vessels and other equipment will appear corrosion phenomenon under the working condition of high temperature and high humidity, which will lead to the thinning of the metal wall thickness. If the wall thickness is thinned to the critical range and not found and treated in time, it is easy to cause leakage accidents, which not only causes great economic losses, but also may endanger the safety of workers. Therefore, it is of great practical significance to implement timely and efficient wall thickness detection on oil and gas pipelines and pressure vessels.

[0003] As a relatively common thickness measurement technology, the wired electromagnetic ultrasonic testing technology can realize the transmission of detection energy and the transmission and reception of ultrasonic data through the cable connection between the transducer and the handheld instrument. However, unlike the wired electromagnetic ultrasonic system, the wireless passive electromagnetic ultrasonic system has the characteristics of three-coil cross coupling and complex circuit structure, and the equivalent circuit diagrams of the excitation and reception stages are different, so the existing resonance design method cannot be directly applied (the complex circuit of the wireless passive electromagnetic ultrasonic system).

[0004] After further research, the inventors found that the existing design method needs to accurately quantify various electrical parameters (such as self-inductance, mutual inductance, resistance, etc.) in the wireless passive electromagnetic ultrasonic system when designing the resonance circuit of the wireless passive electromagnetic ultrasonic system, and needs to calculate many information such as mapping impedance and resonance capacitance, which makes the design process tedious and susceptible to parameter errors. Therefore, it is urgent for technicians in the field to develop a new design method for a wireless passive electromagnetic ultrasonic testing system to solve the above technical problems. SUMMARY

[0005] The present application provides a design method for a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines, which utilizes mutual inductance effect to directly couple the mapping impedance between the coils into the corresponding circuit without quantifying all electrical parameters in the electromagnetic ultrasonic testing system. At the same time, the design method also independently calculates and optimizes the resonance capacitance parameters for the different circuit characteristics of the excitation and reception stages of the wireless passive electromagnetic ultrasonic testing system, accurately realizes the resonance matching of the multi-coil coupling system, thereby significantly improving the transduction efficiency of the wireless passive electromagnetic ultrasonic testing system and improving the signal-to-noise ratio of the signal.

[0006] To solve the above technical problems, the present application adopts the following technical scheme: The application discloses a design method of a wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines. Step S1: according to detection work requirements, the structure of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed is determined; The equivalent circuit diagram of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed is drawn; Step S2: based on the equivalent circuit diagram of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed obtained in step S1, the receiving coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed is separated from the host receiving end; The equivalent inductance of the receiving coil is measured and the equivalent resistance , and the resonant capacitor required for matching the host receiving end is calculated . Step S3: based on the resonant capacitor required for matching the host receiving end obtained in step S2 , the resonant circuit of the host receiving end is determined; Step S4: based on the equivalent circuit diagram of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed obtained in step S1, the EMAT coil and the transducer coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed are separated, and the EMAT coil is tightly attached to the oil and gas pipeline to be detected; The equivalent inductance of the EMAT coil is measured and the equivalent resistance , and the resonant capacitor required for matching the EMAT coil is calculated . Step S5: based on the equivalent circuit diagram of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed obtained in step S1, the transducer coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed is separated, and the transducer coil is suspended in air and surrounded by no metal medium; The equivalent inductance of the transducer coil is measured and the equivalent resistance , and the resonant capacitor required for matching the transducer coil in the excitation stage is calculated as and the resonant capacitor required for matching the transducer unit in the excitation stage is calculated as ; wherein, . Step S6: based on the resonant capacitor required for matching the transducer unit in the excitation stage obtained in step S5 , the resonant circuit of the transducer unit in the excitation stage is determined; Step S7: connecting the structural units separated in step S2, step S4, step S5 and the resonance circuit of the host receiving end determined in step S3, the resonance circuit of the transducer unit determined in step S6 back to the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed; keeping the position of the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed unchanged, and separating it from the host excitation end; Measuring the equivalent inductance of the excitation coil and the equivalent resistance , and calculating the resonance capacitance required to match the host excitation end in the excitation stage as ; Step S8: separating the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed based on the equivalent circuit diagram of the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed obtained in step S1; Measuring the equivalent inductance of the excitation coil and the equivalent resistance , and calculating the parallel resonance capacitance required to match the host excitation end in the receiving stage as ; Step S9: determining the resonance circuit of the host excitation end in the receiving stage according to the parallel resonance capacitance required to match the host excitation end in the receiving stage obtained in step S8 ; Step S10: connecting the structural units separated in step S7, step S8 and the resonance circuit of the host receiving end determined in step S3, the resonance circuit of the host excitation end in the receiving stage determined in step S9 back to the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed; keeping the position of the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed unchanged, and separating the EMAT coil from the transducer coil; Measuring the equivalent inductance of the transducer coil and the equivalent resistance , and calculating the resonance capacitance required to match the transducer coil in the receiving stage and the resonance capacitance required to match the transducer unit in the receiving stage , wherein .

[0007] More preferably, the following steps are further included: Step S11: calculating the resonance capacitance required to match the transducer unit ; wherein ; determining the resonance circuit of the transducer unit according to the resonance capacitance required to match the transducer unit obtained .

[0008] More preferably, the structure of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed in step S1 comprises at least a wireless passive electromagnetic ultrasonic transducer unit, a wireless coupling unit and an electromagnetic ultrasonic host; The wireless passive electromagnetic ultrasonic transducer unit comprises an electromagnetic ultrasonic transducer and a transducer coil; the wireless coupling unit comprises an excitation coil and a receiving coil; and the electromagnetic ultrasonic host comprises an excitation end and a receiving end. The electromagnetic ultrasonic transducer comprises a permanent magnet, a magnet back plate, an EMAT coil and a transducer shell, wherein the permanent magnet, the magnet back plate and the EMAT coil are coaxially arranged in the transducer shell from top to bottom.

[0009] More preferably, the first resonance capacitor required for parallel resonance in steps S2, S5 and S8 satisfies: ; Wherein, is the resonance frequency of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed, is the measured inductance of the coil.

[0010] More preferably, the second resonance capacitor required for parallel resonance in steps S4, S7 and S10 satisfies: ; Wherein, is the resonance frequency of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed, is the measured inductance of the coil, is the measured resistance of the coil.

[0011] The application provides a design method of a wireless passive electromagnetic ultrasonic detection system for an oil and gas pipeline. Specifically, the design method of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline comprises the following steps: step S1: determining the structure of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed according to the detection requirements; obtaining the equivalent circuit diagrams of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed; step S2: based on the equivalent circuit diagrams of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed obtained in step S1, separating the receiving coil in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed from the host receiving end; measuring the equivalent inductance and the equivalent resistance of the receiving coil, and calculating the resonance capacitor required for matching the host receiving end; step S3: based on the resonance capacitor ​​, determine the resonance circuit of the host receiving end; step S4: based on the equivalent circuit diagram obtained in step S1 of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, separate the EMAT coil and the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, and make the EMAT coil close to the oil and gas pipeline to be measured; measure the equivalent inductance and equivalent resistance of the EMAT coil, and calculate the resonance capacitance needed to match the EMAT coil; Step S5: based on the equivalent circuit diagram obtained in step S1 of the excitation stage of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, separate the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, and make the transducer coil suspended in the air without metal medium around; measure the equivalent inductance and equivalent resistance of the transducer coil, and calculate the resonance capacitance needed to match the transducer coil in the excitation stage and the resonance capacitance needed to match the transducer unit in the excitation stage; Step S6: based on the resonance capacitance needed to match the transducer unit in the excitation stage obtained in step S5, determine the resonance circuit of the transducer unit in the excitation stage; step S7: connect the structure units separated in steps S2, S4 and S5, the resonance circuit of the host receiving end determined in step S3, and the resonance circuit of the transducer unit in the excitation stage determined in step S6 back to the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; keep the position of the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline unchanged, and separate it from the host excitation end; measure the equivalent inductance and equivalent resistance of the excitation coil, and calculate the resonance capacitance needed to match the host excitation end in the excitation stage; Step S8: based on the equivalent circuit diagram obtained in step S1 of the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, separate the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; measure the equivalent inductance and equivalent resistance of the excitation coil, and calculate the parallel resonance capacitance needed to match the host excitation end in the receiving stage; Step S9: according to the parallel resonance capacitance , determine the resonance circuit of the host excitation end in the receiving stage; step S10: connect the structural units separated in step S7, step S8, the resonance circuit of the host receiving end determined in step S3, and the resonance circuit of the host excitation end in the receiving stage determined in step S9 back to the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed; keep the position of the transduction coil unchanged in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed, separate the EMAT coil from the transduction coil; measure the equivalent inductance of the transduction coil and the equivalent resistance , and calculate the resonance capacitance required for the matching receiving stage transduction coil and the resonance capacitance required for the receiving stage transducer unit .

[0012] The design method of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline has at least the following technical advantages compared with the prior art: (1) The design method directly couples the mapping impedance between the coils to the corresponding circuit, without quantifying all the electrical parameters of the system, so as to calculate the mapping impedance and the resonance capacitance; the resonance capacitance parameters are independently calculated and optimized according to the different circuit characteristics of the excitation stage and the receiving stage in the wireless passive electromagnetic ultrasonic detection process, so as to realize the precise resonance matching of the multi-coil coupling system and simplify the design complexity of the multi-coil parallel resonance network.

[0013] (2) Compared with the existing wireless passive electromagnetic ultrasonic detection system, the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline obtained by the design method greatly improves the wireless energy transmission efficiency of each resonance circuit, can selectively amplify the specific frequency signal, expands the applicable distance range of the detection system, and reduces the demand for transmission power.

[0014] (3) The design method provided by the present application breaks the shackles of the cable and significantly improves the work efficiency of the oil and gas pipeline wall thickness detection; compared with the existing wireless passive piezoelectric ultrasonic technology, it can work normally in various harsh working environments of petrochemical equipment, and does not need to be surface treated. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the following drawings: Figure 1 A flowchart of the design method of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline provided by the present application; Figure 2A schematic diagram of a structure of a wireless passive electromagnetic ultrasonic detection system for an oil and gas pipeline to be designed; Figure 3 A schematic diagram of an equivalent circuit of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline after processing is simplified; Figure 4 A schematic diagram of an equivalent circuit after the back plate eddy current loop 18, the test piece eddy current loop 19 and the EMAT coil 3 are simplified; Figure 5 A schematic diagram of inductance, resistance and frequency variation in an excitation stage of a host receiving end; Figure 6 A simplified circuit diagram of the wireless passive electromagnetic ultrasonic detection system in an excitation stage; Figure 7 A simplified circuit diagram of the wireless passive electromagnetic ultrasonic detection system in a receiving stage; Figure 8a A schematic diagram of experimental results of the wireless passive electromagnetic ultrasonic detection system before a resonance circuit is added; Figure 8b A schematic diagram of experimental results of the wireless passive electromagnetic ultrasonic detection system after the resonance circuit is added.

[0016] Reference signs: 1, permanent magnet; 2, magnet back plate; 3, EMAT coil; 4, transducer shell; 5, transduction coil; 6, excitation coil; 7, receiving coil; 8, transducer unit resonance circuit; 9, host excitation end resonance circuit; 10, host receiving end resonance circuit; 11, electromagnetic ultrasonic host; 12, host excitation end; 13, host receiving end; 14, oil and gas pipeline to be measured; 15, excitation loop; 16, receiving loop; 17, transducer unit loop; 18, back plate eddy current loop; 19, test piece eddy current loop. DETAILED DESCRIPTION

[0017] The present application provides a design method of a wireless passive electromagnetic ultrasonic detection system for an oil and gas pipeline, which utilizes mutual inductance effect to directly couple the impedance between coils into the corresponding circuit without quantifying all electrical parameters in the electromagnetic ultrasonic detection system. Meanwhile, the design method independently calculates and optimizes the resonance capacitance parameters according to the different circuit characteristics in the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system, and precisely realizes the resonance matching of the multi-coil coupling system, thereby significantly improving the transduction efficiency of the wireless passive electromagnetic ultrasonic detection system and improving the signal-to-noise ratio of the signal.

[0018] Specifically, the present application provides a design method of a wireless passive electromagnetic ultrasonic detection system for an oil and gas pipeline, as shown in Figure 1 The method comprises the following steps: Step S1: According to the detection work requirements, the structure of the wireless passive electromagnetic ultrasonic detection system to be designed for oil and gas pipelines is determined.

[0019] The equivalent circuit diagram of the wireless passive electromagnetic ultrasonic detection system to be designed for oil and gas pipelines is drawn.

[0020] As a more preferred embodiment of the present application, as shown in the step S1, the structure of the wireless passive electromagnetic ultrasonic detection system to be designed for oil and gas pipelines includes at least a wireless passive electromagnetic ultrasonic transducer unit, a wireless coupling unit and an electromagnetic ultrasonic host. Figure 2

[0021] Further, the wireless passive electromagnetic ultrasonic transducer unit includes an electromagnetic ultrasonic transducer and a transducer coil 5; the wireless coupling unit includes an excitation coil 6 and a receiving coil 7; the electromagnetic ultrasonic host 11 includes a host excitation end 12 and a host receiving end 13. The electromagnetic ultrasonic transducer includes a permanent magnet 1, a magnet back plate 2, an EMAT coil 3 and a transducer shell 4; wherein the permanent magnet 1, the magnet back plate 2 and the EMAT coil 3 are coaxially symmetric and are installed in the transducer shell 4 from top to bottom.

[0022] It should be noted that the purpose of such arrangement is to understand the wireless passive electromagnetic ultrasonic detection system to be designed for oil and gas pipelines as a whole composed of multiple electromagnetic coupling objects. By determining the parallel resonant circuits (such as the transducer unit resonant circuit 8, the host excitation end resonant circuit 9, the host receiving end resonant circuit 10, etc.) to be added to the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines, the specific structure of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines is finally designed.

[0023] In this process, first, the circuit of the wireless passive electromagnetic ultrasonic detection system to be designed for oil and gas pipelines is simplified, as shown in Figure 3 At this time, the main current loop in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines includes the following five: excitation loop 15, receiving loop 16, transducer unit loop 17, back plate eddy current loop 18 and test piece eddy current loop 19. Since the electrical parameters of the back plate eddy current loop 18 and the test piece eddy current loop 19 cannot be measured and do not participate in the resonance, the back plate eddy current loop 18, the test piece eddy current loop 19 and the EMAT coil 3 are further regarded as a coil connected to the power supply, thereby simplifying Figure 3 to the form as shown in Figure 4

[0024] ​​It should be noted that, in order to facilitate the understanding of the present application by those skilled in the art, the inventors further provide a wireless passive electromagnetic ultrasonic detection system as a reference. Among them, the permanent magnet 1 is selected as a cylindrical permanent magnet, and the material is neodymium iron boron. In order to make the overall volume of the electromagnetic ultrasonic transducer relatively small, the diameter of the cylindrical permanent magnet is 30mm, and the height is 10mm. The EMAT coil 3 selects a spiral coil. Among them, the ratio of the diameter of the spiral coil to the diameter of the cylindrical permanent magnet is 1:1.2, and the wire diameter is 0.2mm. In addition, the transduction coil 5, the excitation coil 6 and the receiving coil 7 are all selected as Litz wire and the same coil unit, the coil diameter is 40mm, the inner diameter is 20mm, and the wire diameter is 0.35mm.

[0025] Step S2: Based on the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines obtained in step S1, the receiving coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines is separated from the host receiving end.

[0026] The equivalent inductance L1 and the equivalent resistance R1 of the receiving coil are measured, and the resonant capacitance required for matching the host receiving end is calculated .

[0027] Step S3: Based on the resonant capacitance required for matching the host receiving end obtained in step S2, the resonant circuit of the host receiving end is determined.

[0028] After completing the above step S1, steps S2 and S3 are continued. It is worth noting that, unlike existing wireless energy transmission systems, the wireless passive electromagnetic ultrasonic detection system designed by the design method provided by the present application has essential differences in the circuit characteristics of the excitation stage and the receiving stage. Specifically, the excitation stage generates a high-frequency electric signal at the host excitation end and transmits along the direction of the excitation coil-transduction coil-electromagnetic ultrasonic transducer; then the electromagnetic ultrasonic transducer converts alternating current into ultrasonic waves. The receiving stage is when the ultrasonic wave reflects back to the electromagnetic ultrasonic transducer, first converts the ultrasonic wave into alternating current, and then transmits to the host receiving end along the direction of the electromagnetic ultrasonic transducer-transduction coil-receiving coil.

[0029] Therefore, the inductance, resistance and frequency change of the host receiving end excitation stage can be referred to as shown in Figure 5 . Among them, for the wireless passive electromagnetic ultrasonic detection system, in the excitation stage, the host excitation end 12 is the power supply of the wireless passive electromagnetic ultrasonic detection system, and the EMAT coil 3 is equivalent to the load, which can be referred to as shown in Figure 6 . And in the receiving stage, the EMAT coil 3 is used to receive weak ultrasonic echo signals, and its function is equivalent to a power supply, while the host excitation end 12 is regarded as a load, which can be referred to as shown in Figure 7 .​

[0030] In addition, in the wireless energy transmission process, the compensation capacitor of the secondary circuit is to make the secondary circuit in a resonant state, so the mapping impedance of the primary circuit does not need to be considered. The compensation capacitor of the primary circuit is to eliminate the reactive power of the power supply, so the mapping impedance of the secondary circuit needs to be considered. Based on this, when the receiving coil 7 is in the receiving circuit 16 as the secondary circuit, the influence of the transducer unit circuit 17 and the excitation circuit 15 does not need to be considered. That is, when measuring the inductance and resistance of the receiving coil 7, the receiving coil 7 does not need to be electromagnetically coupled with the excitation coil 6 and the transducer coil 5.

[0031] It needs to be pointed out that when measuring the receiving coil in step S2, the electromagnetic coupling object of the receiving coil 7 needs to be additionally considered. This is because in the actual thickness measurement work, the receiving coil 7 can have a metal back plate, and its position can be close to other components in the system or the oil and gas pipeline 14 to be measured. Therefore, the equivalent inductance L1 and the equivalent resistance R1 of the receiving coil 7 need to be measured at the actual working position of the receiving coil 7.

[0032] It is worth noting that since Therefore, as a more preferred embodiment of the present application, during the measurement in step S2, the first resonance capacitor C1 required for parallel resonance satisfies: ; wherein f is the resonant frequency of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed, and L is the measured inductance of the coil.

[0033] Then, the internal resistance of the host receiving end is also considered in the calculation. Finally, the determined resonant circuit 10 of the host receiving end is connected in parallel with the receiving coil 7, and the position of the resonance peak is measured and observed to verify whether the target resonant frequency is matched, and the result can be referred to as shown in Figure 5 Based on the above steps, the equivalent inductance and the equivalent resistance of the receiving coil 7 are 5.73 , 1.32 , respectively, and the resonant capacitor required to match the host receiving end 13 is .

[0034] Step S4: Based on the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed obtained in step S1, the EMAT coil and the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline to be designed are separated, and the EMAT coil is tightly attached to the oil and gas pipeline to be measured.

[0035] The equivalent inductance L2 and the equivalent resistance R2 of the EMAT coil are measured, and the resonant capacitor C2 required to match the EMAT coil is calculated .

[0036] After the above steps S2 and S3 are completed, step S4 is continued. It is worth noting that in the process of measuring the equivalent inductance and equivalent resistance of the EMAT coil, since is not much smaller than . Therefore, as a more preferred embodiment of the present application, during the measurement in step S4, the second resonance capacitor required for parallel resonance satisfies: ; wherein f is the resonance frequency of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, L is the measured inductance of the coil, and R is the measured resistance of the coil.

[0037] Based on the above steps, the equivalent inductance and equivalent resistance of the EMAT coil 3 are respectively (465 , 1.27 ), and the resonance capacitor required for matching the EMAT coil 3 is .

[0038] Step S5: Based on the equivalent circuit diagram of the excitation stage of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline obtained in step S1, separate the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline, so that the transducer coil is suspended in the air and surrounded by no metal medium.

[0039] Measure the equivalent inductance L3 and equivalent resistance R3 of the transducer coil, and calculate the resonance capacitor required for matching the transducer coil in the excitation stage as and the resonance capacitor required for matching the transducer unit in the excitation stage as ; wherein .

[0040] Step S6: Based on the resonance capacitor required for matching the transducer unit in the excitation stage obtained in step S5, determine the resonance circuit of the transducer unit in the excitation stage.

[0041] Step S7: Connect the structural units separated in steps S2, S4, and S5, the resonance circuit of the host receiving end determined in step S3, and the resonance circuit of the transducer unit in the excitation stage determined in step S6 back to the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; keep the position of the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline unchanged, and separate it from the host excitation end.

[0042] Measure the equivalent inductance L4 and equivalent resistance R4 of the excitation coil, and calculate the resonance capacitor required for matching the host excitation end in the excitation stage as .

[0043] After the above step S4 is completed, steps S5-S7 are implemented. Among them, steps S5-S7 target the resonant circuit of the excitation stage. Among them, in the excitation stage, the transducer unit loop 17 works as a secondary loop. In addition, when measuring the equivalent inductance L3 and the equivalent resistance R3 of the transducer coil, the transducer coil 5 does not need to be electromagnetically coupled with the excitation coil 6 and the receiving coil 7. This is because the transducer coil has a small degree of coupling with other metal materials between the excitation coil 6 and the receiving coil 7; therefore, it is preferred to be suspended in the air to avoid being affected by other metals during the measurement.

[0044] Then, the calculated resonant capacitance required for the transducer coil in the matching excitation stage is and the resonant capacitance required for the transducer unit in the matching excitation stage is The inductance and resistance of the whole are measured in parallel with the transducer coil 5 to verify whether the target resonant frequency is matched.

[0045] Based on the above steps, the calculated equivalent inductance and equivalent resistance of the transducer coil 5 are (4.17 , 617 ), the resonant capacitance required for the transducer coil 5 in the matching excitation stage is , and the resonant capacitance required for the transducer unit in the matching excitation stage is Finally, the matching transducer unit resonant circuit 8 in the excitation stage is determined according to the obtained matching transducer unit resonant capacitance .

[0046] Then, the structural units separated in steps S2, S4, and S5, the resonant circuit of the host receiving end determined in step S3, and the resonant circuit of the transducer unit in the excitation stage determined in step S6 are connected back to the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed; and the excitation coil 6 is selected to be separated from the host excitation end 12 and fixed in place (above the transducer coil 5). The equivalent inductance L4 and the equivalent resistance R4 of the excitation coil are measured, and the resonant capacitance required for the host excitation end in the matching excitation stage is calculated as .

[0047] Specifically, in the excitation stage, the excitation loop 15 works as a primary loop, and when measuring the inductance and resistance of the excitation coil, the excitation coil 6 needs to be electromagnetically coupled with the transducer coil 5 and the receiving coil 7. For the receiving coil 7, it can be selected to be connected with the host receiving end 13 or in series with an impedance having the same resistance as the host receiving end 13. Among them, the calculation formula of the second resonant capacitance required for parallel resonance in this measurement process has been recorded in step S4 and will not be described in detail here.

[0048] Based on the above steps, the equivalent inductance and equivalent resistance of the excitation coil 6 are 2.2 , 14.5 , respectively, and the resonant capacitance required to match the excitation stage of the excitation coil 6 is .

[0049] Step S8: Based on the equivalent circuit diagram of the receiving stage of the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline obtained in step S1, the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is separated.

[0050] The equivalent inductance L5 and equivalent resistance R5 of the excitation coil are measured, and the parallel resonant capacitance required to match the host excitation end of the receiving stage is calculated to be .

[0051] Step S9: According to the parallel resonant capacitance required to match the host excitation end of the receiving stage obtained in step S8 , the resonant circuit of the host excitation end of the receiving stage is determined.

[0052] Step S10: The structural units separated in steps S7 and S8, the resonant circuit of the host receiving end determined in step S3, and the resonant circuit of the host excitation end of the receiving stage determined in step S9 are connected back to the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; the position of the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is kept unchanged, and the EMAT coil is separated from the transducer coil.

[0053] The equivalent inductance L6 and equivalent resistance R6 of the transducer coil are measured, and the resonant capacitance required to match the transducer coil in the receiving stage is calculated to be and the resonant capacitance required for the transducer unit in the receiving stage is , wherein, .

[0054] After completing the above steps S5-S7, steps S8-S10 are continued. Among them, steps S8-S10 aim to determine the resonant circuits of the receiving stage. Specifically, in the receiving stage, the excitation circuit 15 serves as the primary circuit; therefore, when measuring it, the electromagnetic coupling object of the excitation coil 6 needs to be considered.

[0055] It is worth noting that in actual thickness measurement work, the excitation coil 6 may have a metal backplate, and its position may be close to other components in the system or the oil / gas pipeline 14 to be measured; therefore, the equivalent inductance L5 and equivalent resistance R5 of the excitation coil are measured at the actual working position of the excitation coil 6. In the receiving stage, the excitation circuit 15 acts as a secondary circuit, and when measuring inductance and resistance, it is not necessary for the excitation coil 6 to be electromagnetically coupled to the transducer coil 5 and the receiving coil 7. The first resonant capacitor required for parallel resonance... The calculation formula has been recorded in step S2 and will not be elaborated on here.

[0056] Based on the above steps, the equivalent inductance and equivalent resistance of the excitation coil 6 are calculated to be (6.42) 1.62 The resonant capacitance required for the excitation coil 6 in the matching receiving stage is... Then, based on the calculated resonant capacitance required for the excitation coil 6 in the matching receiving stage, The host excitation end resonant circuit 9 in the receiving stage was determined.

[0057] Then, in the receiving stage, transducer unit circuit 17 serves as the primary circuit. When measuring the equivalent inductance and equivalent resistance of the transducer coil, electromagnetic coupling is required between the transducer coil 5, the excitation coil 6, and the receiving coil 7. For the receiving coil 7, an impedance with the same internal resistance as the host receiver terminal 13 can be connected in series. The second resonant capacitor required for parallel resonance... The calculation formula has been recorded in step S4 and will not be elaborated on here.

[0058] Based on the above steps, the equivalent inductance and equivalent resistance of the transducer coil 5 are obtained as (1.53) 10.54 The resonant capacitance required for the transducer coil 5 in the matching receiving stage is... The resonant capacitance required for the transducer unit in the matching receiving stage is .

[0059] On the other hand, as a preferred embodiment of the present invention, the design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines provided by the present invention further includes the following steps: Step S11: Calculate the resonant capacitance required for the matching transducer unit. ;in, ; Based on the required resonant capacitance of the matched transducer unit Determine the resonant circuit of the transducer unit.

[0060] It is worth noting that the aforementioned steps are calculated respectively to obtain the resonance capacitance of the host receiving end resonance circuit , the resonance capacitance of the host excitation end resonance circuit . In step S11, the resonance capacitance required to match the transducer unit is further calculated.

[0061] The experimental results of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines designed by the design method of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines provided by the application before and after adding a resonance circuit are compared (the experimental results of the wireless passive electromagnetic ultrasonic detection system before adding the resonance circuit can be referred to as shown in Figure 8a ; the experimental results of the wireless passive electromagnetic ultrasonic detection system after adding the resonance circuit can be referred to as shown in Figure 8b ). It can be found that the design method of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines provided by the application simplifies the design and calculation of parallel resonance of a complex electrical system, significantly improves the transduction efficiency and improves the signal signal-to-noise ratio.

[0062] The application provides a design method of a wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines. Specifically, the design method of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines comprises the following steps: step S1: determining the structure of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed according to the detection work requirements; drawing the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed; step S2: based on the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed obtained in step S1, separating the receiving coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed from the host receiving end; measuring the equivalent inductance L1 and the equivalent resistance R1 of the receiving coil, and calculating the resonance capacitance required to match the host receiving end; step S3: based on the resonance capacitance required to match the host receiving end obtained in step S2, determining the resonance circuit of the host receiving end; step S4: based on the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed obtained in step S1, separating the EMAT coil and the transduction coil in the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines to be designed, and making the EMAT coil close to the oil and gas pipeline to be measured; measuring the equivalent inductance L2 and the equivalent resistance R2 of the EMAT coil, and calculating the resonance capacitance ; Step S5: based on the equivalent circuit diagram obtained in step S1, the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is separated, the transducer coil is suspended in the air and surrounded by no metal medium; the equivalent inductance L3 and the equivalent resistance R3 of the transducer coil are measured, and the resonant capacitor required for matching the transducer coil in the excitation stage is calculated as And the resonant capacitor required for matching the transducer unit in the excitation stage is ; Step S6: based on the resonant capacitor required for matching the transducer unit in the excitation stage obtained in step S5 , the resonant circuit of the excitation stage transducer unit is determined; Step S7: the structure units separated in steps S2, S4, S5, the resonant circuit of the host receiving end determined in step S3, and the resonant circuit of the excitation stage transducer unit determined in step S6 are connected back to the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; the position of the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is kept unchanged, and it is separated from the host excitation end; the equivalent inductance L4 and the equivalent resistance R4 of the excitation coil are measured, and the resonant capacitor required for matching the host excitation end in the excitation stage is calculated as ; Step S8: based on the equivalent circuit diagram obtained in step S1, the excitation coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is separated; the equivalent inductance L5 and the equivalent resistance R5 of the excitation coil are measured, and the parallel resonant capacitor required for matching the host excitation end in the receiving stage is calculated as ; Step S9: according to the parallel resonant capacitor required for matching the host excitation end in the receiving stage obtained in step S8 , the resonant circuit of the host excitation end in the receiving stage is determined; Step S10: the structure units separated in steps S7, S8, the resonant circuit of the host receiving end determined in step S3, and the resonant circuit of the host excitation end in the receiving stage determined in step S9 are connected back to the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline; the position of the transducer coil in the wireless passive electromagnetic ultrasonic detection system for the designed oil and gas pipeline is kept unchanged, and the EMAT coil is separated from the transducer coil; the equivalent inductance L6 and the equivalent resistance R6 of the transducer coil are measured, and the resonant capacitor required for matching the transducer coil in the receiving stage is calculated as And the resonant capacitor required for matching the transducer unit in the receiving stage is .

[0063] The design method of the wireless passive electromagnetic ultrasonic detection system for the oil and gas pipeline has at least the following technical advantages compared with the prior art: (1) The design method directly couples the mapping impedance between each coil to the corresponding circuit, without quantifying all electrical parameters of the system, so as to calculate the mapping impedance and the resonant capacitor; the resonant capacitor parameters are independently calculated and optimized according to the different circuit characteristics of the excitation stage and the receiving stage in the wireless passive electromagnetic ultrasonic detection process, so as to realize the precise resonant matching of the multi-coil coupling system and simplify the design complexity of the multi-coil parallel resonant network.

[0064] (2) Compared with the existing wireless passive electromagnetic ultrasonic detection system, the wireless passive electromagnetic ultrasonic detection system for oil and gas pipelines obtained by the design method greatly improves the wireless energy transmission efficiency of each resonant circuit, can selectively amplify the specific frequency signal, expands the applicable distance range of the detection system, and reduces the demand for transmission power.

[0065] (3) The design method provided by the present application breaks the shackles of the cable and significantly improves the working efficiency of the oil and gas pipeline wall thickness detection; compared with the existing wireless passive piezoelectric ultrasonic technology, it can work normally in various harsh working environments of petrochemical equipment, and does not need to be surface treated.

[0066] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A design method for a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines, characterized in that, The steps include the following: Step S1: Determine the structural composition of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed based on the testing requirements; The equivalent circuit diagrams of the excitation and receiving stages of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed are drawn. Step S2: Based on the equivalent circuit diagram of the excitation stage and the receiving stage of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed obtained in Step S1, the receiving coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed is separated from the host receiving end. The equivalent inductance L1 and equivalent resistance R1 of the receiving coil were measured, and the resonant capacitance required to match the receiver of the host was calculated. ; Step S3: Based on the resonant capacitance required for the matching host receiver obtained in step S2. Determine the resonant circuit of the host receiver; Step S4: Based on the equivalent circuit diagram of the excitation and receiving stages of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed obtained in step S1, separate the EMAT coil and the transducer coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed, and make the EMAT coil tightly attached to the oil and gas pipeline to be tested. Measure the equivalent inductance L2 and equivalent resistance R2 of the EMAT coil, and calculate the resonant capacitance required to match the EMAT coil. ; Step S5: Based on the equivalent circuit diagram of the excitation stage of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed obtained in step S1, separate the transducer coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed, so that the transducer coil is suspended in the air and there is no metal medium around it. The equivalent inductance L3 and equivalent resistance R3 of the transducer coil were measured, and the resonant capacitance required for the transducer coil during the matching excitation stage was calculated. The resonant capacitance required by the transducer unit during the matching excitation stage is ;in, ; Step S6: Based on the resonant capacitance required by the transducer unit in the matching excitation stage obtained in step S5. Determine the resonant circuit of the transducer unit during the excitation phase; Step S7: Connect the structural units separated in steps S2, S4, and S5, the resonant circuit of the host receiver determined in step S3, and the resonant circuit of the transducer unit in the excitation stage determined in step S6 back to the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed; keep the position of the excitation coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed unchanged, and separate it from the host excitation end. The equivalent inductance L4 and equivalent resistance R4 of the excitation coil were measured, and the resonant capacitance required at the host excitation terminal during the matching excitation stage was calculated. ; Step S8: Based on the equivalent circuit diagram of the receiving stage of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed obtained in step S1, separate the excitation coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed. The equivalent inductance L5 and equivalent resistance R5 of the excitation coil were measured, and the parallel resonant capacitance required at the host excitation end for the matching receiving stage was calculated. ; Step S9: Based on the parallel resonant capacitor required by the host excitation end in the matching reception stage obtained in step S8. Determine the resonant circuit at the host excitation end during the receiving phase; Step S10: Connect the structural units separated in steps S7 and S8, the resonant circuit of the host receiver determined in step S3, and the resonant circuit of the host excitation end in the receiving stage determined in step S9 back to the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed; keep the position of the transducer coil in the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed unchanged, and separate the EMAT coil from the transducer coil. The equivalent inductance L6 and equivalent resistance R6 of the transducer coil are measured, and the resonant capacitance required for the transducer coil in the matching receiving stage is calculated. and the resonant capacitance required by the transducer unit in the receiving stage ,in, .

2. The design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines according to claim 1, characterized in that, It also includes the following steps: Step S11: Calculate the resonant capacitance C required for the matching transducer unit. t ;in, ; Based on the required resonant capacitance C of the matched transducer unit t Determine the resonant circuit of the transducer unit.

3. The design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines according to claim 1, characterized in that, The structure of the wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines to be designed in step S1 includes at least a wireless passive electromagnetic ultrasonic transducer unit, a wireless coupling unit, and an electromagnetic ultrasonic host. The wireless passive electromagnetic ultrasonic transducer unit includes an electromagnetic ultrasonic transducer and a transducer coil; the wireless coupling unit includes an excitation coil and a receiving coil; and the electromagnetic ultrasonic host includes an excitation end and a receiving end. The electromagnetic ultrasonic transducer includes a permanent magnet, a magnet backplate, an EMAT coil, and a transducer housing; the permanent magnet, the magnet backplate, and the EMAT coil are symmetrical about their central axis and are installed in the transducer housing from top to bottom.

4. The design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines according to claim 1, characterized in that, In steps S2, S5, and S8, the first resonant capacitor C1 required for parallel resonance satisfies: ; Where f is the resonant frequency of the wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines to be designed, and L is the measured coil inductance.

5. The design method of a wireless passive electromagnetic ultrasonic testing system for oil and gas pipelines according to claim 1, characterized in that, In steps S4, S7, and S10, the second resonant capacitor C2 required for parallel resonance satisfies: ; Where f is the resonant frequency of the wireless passive electromagnetic ultrasonic testing system for the oil and gas pipeline to be designed, L is the measured coil inductance, and R is the measured coil resistance.

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