Electromagnetic ultrasonic online monitoring probe, device and method for steam pipelines with coating

Abstract

This invention discloses an electromagnetic ultrasonic online monitoring probe, device, and method for steam pipelines with a coating layer. The probe includes: a butterfly coil for supplying a DC-like current, or simultaneously supplying a DC-like excitation current and a strong pulse excitation current; and a zigzag coil for supplying a strong pulse excitation current. The zigzag coils are unequally spaced, with the spacing gradually decreasing from the input end to the output end. Supplying a DC-like excitation current into the butterfly coil generates a bias magnetic field; supplying a strong pulse excitation current into the butterfly coil excites ultrasonic body waves, while supplying a strong pulse excitation current into the zigzag coil excites ultrasonic guided waves, thereby enabling pipeline wall thickness and defect detection. The guided waves excited by the unequally spaced zigzag coils exhibit Chirp signal characteristics, allowing for pulse compression to improve the signal-to-noise ratio and resolution of the ultrasonic echo signal. The probe is small in size, unaffected by Curie temperature, and suitable for continuous high-temperature detection and detection in narrow areas.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic testing technology, and in particular to an electromagnetic ultrasonic online monitoring probe, device, and method for steam pipelines with a coating layer. Background Technology

[0002] Existing non-destructive testing (NDT) technologies struggle to achieve real-time, unmanned, intelligent monitoring of the entire process of wall thinning and defect propagation in coated high-temperature, high-pressure steam pipelines. The challenges lie in: ① Traditional sensor technologies are ill-suited for continuous online detection and monitoring at 550°C. Corresponding ultra-high temperature piezoelectric sensors are still in the experimental development stage, extremely expensive, and difficult to widely apply. ② Existing detection methods are ill-suited to the unique steam pipeline structure of "outer steel or aluminum pipe - 7~120mm insulation layer - working steel pipe," making it difficult to measure corrosion thinning and detect defects in the working steel pipe without damaging the outer steel pipe and insulation layer. ③ Traditional defect detection relies on a PC as the terminal, manually identifying ultrasonic A-scan signals collected by the PC for defect location. This method suffers from low portability of remote data and has not yet overcome the limitations of the traditional PC-based monitoring terminal for future unmanned, intelligent detection systems.

[0003] Piezoelectric ultrasound, high-temperature moiré ultrasound, electromagnetic ultrasound, and laser ultrasound are all commonly used high-temperature ultrasonic testing methods. Piezoelectric ultrasound requires a coupling agent, limiting its ability to perform prolonged testing at high temperatures. Air-coupled ultrasound, which does not require a coupling agent, suffers from excessively long residual resonance of the initial ultrasonic signal, low ultrasonic frequency, and is primarily used for transmission methods, making it suitable only for porous materials such as composites, wood, and ceramics. Laser ultrasound and electromagnetic ultrasound, with their advantages of non-contact operation, no need for a coupling agent, and ease of exciting various ultrasonic waves, are widely recognized by scholars both domestically and internationally as the most suitable and already applied key non-destructive testing technologies in ultra-high temperature environments. However, laser ultrasound testing instruments are bulky, expensive, and have stringent environmental requirements.

[0004] Electromagnetic ultrasound (EMAT) can directly excite ultrasonic waves on the surface of metal samples based on the Lorentz force and magnetostriction effect, without contact with the sample or coupling agent. Traditional EMAT requires permanent magnets and electromagnets, which easily attract ferromagnetic particles, resulting in large probe size, low transduction efficiency, and the residual magnetic induction intensity of permanent magnets weakening or disappearing in high-temperature environments due to the Curie temperature, making it unsuitable for continuous high-temperature detection and detection in narrow areas. Summary of the Invention

[0005] This invention provides an electromagnetic ultrasonic online monitoring probe, device, and method for coated steam pipelines, to solve the problem that existing detection technologies are difficult to apply to continuous non-destructive testing of coated high-temperature and high-pressure steam pipelines in high-temperature environments.

[0006] Firstly, an electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer is provided, comprising:

[0007] A butterfly coil is used to pass a DC-like current, or simultaneously pass a DC-like excitation current and a strong pulse excitation current.

[0008] A zigzag coil is disposed below the butterfly coil and is used to pass a strong pulse excitation current; the zigzag coil is a zigzag coil with unequal spacing, and the spacing gradually decreases from the input end to the output end.

[0009] During implementation, the electromagnetic ultrasonic online monitoring probe is attached tightly to the outer wall of the working steel pipe of the steam pipeline. The probe penetrates the insulation cotton through a high-temperature resistant lead wire. Without removing or damaging the insulation layer, continuous non-destructive monitoring can be achieved under permanent installation conditions of high-temperature and high-pressure steam pipelines with insulation layers. When monitoring the wall thickness of the working steel pipe, a near-DC excitation current is first passed through the butterfly coil to generate a bias magnetic field. After the near-DC excitation current stabilizes, a strong pulse excitation current is simultaneously passed through the butterfly coil to generate ultrasonic bulk waves on the working steel pipe. The echo signal of the ultrasonic bulk waves is received through the butterfly coil, which is used to detect the wall thickness and internal defects of the working steel pipe. When monitoring defects in the working steel pipe, a near-DC excitation current is first passed through the butterfly coil to generate a bias magnetic field. After the near-DC excitation current stabilizes, a strong pulse excitation current is simultaneously passed through the zigzag coil to generate ultrasonic guided waves on the working steel pipe. The echo signal of the ultrasonic guided waves is received through the zigzag coil, which is used to detect surface defects in thick-walled working steel pipes or defects in thin-walled working steel pipes throughout their thickness. Furthermore, a unequal-pitched zigzag coil is proposed, whose excited ultrasonic guided waves have chirp signal characteristics. Pulse compression technology can be implemented to improve the signal-to-noise ratio and resolution of the ultrasonic guided wave echo signal, thereby improving the detection accuracy.

[0010] Furthermore, the position of each turn of the conductor in the zigzag coil satisfies the following condition: px n 2 +f 0 vx n -nv 2 / 2=0, where p This represents the linear frequency modulation rate of the Chirp signal, that is, the rate at which the transient frequency of the Chirp signal changes with time. f 0 represents the lowest frequency of the Chirp signal. v The speed at which ultrasound propagates in the test piece. x n For the first n The spacing between the coil and the first coil of wire is n≥2.

[0011] Furthermore, the portion of the butterfly coil with the current in the same direction covers the entire zigzag coil.

[0012] Furthermore, it also includes: a corundum sheet disposed below the tortuous coil.

[0013] Furthermore, both the zigzag coil and the butterfly coil are made of high-temperature resistant ceramic-coated silver wire with a diameter of 0.05~0.5 mm.

[0014] Secondly, an electromagnetic ultrasonic online monitoring device for steam pipelines with a coating layer is provided, comprising an AD sampling control module, an excitation receiving circuit, and an electromagnetic ultrasonic online monitoring probe as described above, connected in sequence.

[0015] The excitation receiving circuit is used to generate a DC-like excitation current and a strong pulse excitation current to pass the DC-like excitation current and the strong pulse excitation current into the butterfly coil, or to pass the DC-like excitation current into the butterfly coil and the strong pulse excitation current into the zigzag coil; and to detect the detection echo signal received by the butterfly coil or the zigzag coil.

[0016] During implementation, the electromagnetic ultrasonic online monitoring probe is attached tightly to the outer wall of the working steel pipe of the steam pipeline. It penetrates the insulation cotton through the high-temperature resistant lead wire without removing or damaging the insulation layer. The probe, which integrates the AD sampling control module and the excitation receiving circuit, is installed on the outer wall of the outer steel pipe. The excitation receiving circuit is connected to the high-temperature resistant lead wire, thereby realizing continuous non-destructive monitoring of the high-temperature and high-pressure steam pipeline with the coating layer under permanent installation conditions.

[0017] Furthermore, the excitation receiving circuit includes a high-voltage high-pulse excitation module, a low-voltage DC excitation module, an impedance matching module, an echo detection module, and a switching switch; the high-voltage high-pulse excitation module, the low-voltage DC excitation module, the impedance matching module, the echo detection module, and the electromagnetic ultrasonic online monitoring probe are all connected to the switching switch; the low-voltage DC excitation module is always connected to the input terminal of the butterfly coil in the electromagnetic ultrasonic online monitoring probe, and the impedance matching module and the echo detection module are always connected to the output terminals of the butterfly coil and the zigzag coil in the electromagnetic ultrasonic online monitoring probe; when it is necessary to generate ultrasonic guided waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the zigzag coil through the switching switch; when it is necessary to generate ultrasonic body waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the butterfly coil through the switching switch.

[0018] Furthermore, the excitation receiving circuit also includes a sampling current module, which is connected to the impedance matching module.

[0019] Furthermore, it also includes a wireless communication module, which is connected to the AD sampling control module.

[0020] Thirdly, a method for online electromagnetic ultrasonic monitoring of coated steam pipelines is provided, based on the aforementioned online electromagnetic ultrasonic monitoring device for coated steam pipelines, comprising the following steps:

[0021] The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. When the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the butterfly coil to generate ultrasonic body waves in the pipe under test. The butterfly coil receives the ultrasonic body wave echo signal and transmits it to the AD sampling control module.

[0022] The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. Once the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the zigzag coil to generate ultrasonic guided waves in the pipe under test. The zigzag coil receives the ultrasonic guided wave echo signal and transmits it to the AD sampling control module.

[0023] Furthermore, it also includes:

[0024] Obtain the time series of pipe wall thickness at monitoring points, and use a pipe wall thickness reduction early warning algorithm based on gray prediction to monitor and warn of pipe wall thickness reduction at monitoring points;

[0025] The ultrasonic guided wave echo signal of the monitoring point is acquired and imaged to form an ultrasonic imaging atlas;

[0026] The ultrasonic imaging atlas is input into a pre-trained pipeline defect identification model to obtain the pipeline defect type; the pipeline defect identification model is obtained by training a deep neural network model based on historical ultrasonic imaging atlases and corresponding defect types.

[0027] This invention proposes an electromagnetic ultrasonic online monitoring probe, device, and method for steam pipelines with a coating layer, which has the following advantages:

[0028] (1) Traditional permanent magnet EMAT cannot be used for continuous long-term testing in high-temperature environments because the residual magnetic induction intensity of the permanent magnet weakens or even disappears when it exceeds the Curie temperature. Traditional pulse electromagnet EMAT is bulky and difficult to use for non-destructive testing in narrow spaces. Existing non-destructive testing methods are difficult to use for high-temperature and high-pressure steam pipelines with a coating layer of "outer steel or aluminum pipe - 7~120 mm insulation layer - working steel pipe", and it is difficult to measure the wall thickness corrosion reduction and defect detection of the working steel pipe without damaging the outer steel pipe and insulation layer. This invention proposes to use a coil-only EMAT probe, which is placed close to the outer wall of the working steel pipe and penetrates the insulation cotton through a high-temperature resistant lead. It does not require the removal or damage of the insulation layer and can achieve continuous non-destructive monitoring of high-temperature and high-pressure steam pipelines with a coating layer under permanent installation conditions. The coil-only EMAT probe used in this invention does not require a water-cooling system, permanent magnets, or electromagnets. Instead, a bias magnetic field is generated by passing a DC-like excitation current through the coil. Therefore, it does not require a permanent magnet or electromagnet to provide the bias magnetic field needed for excitation and reception of ultrasonic waves. It is not affected by the Curie point and is suitable for non-destructive testing in high-temperature environments. Its size is greatly reduced, making it suitable for narrow testing occasions. Therefore, the coil-only EMAT technology used in this invention is a key and feasible technology for online non-destructive testing and monitoring of high-temperature and high-pressure steam pipelines with cladding layers.

[0029] (2) A coil-only EMAT, composed of a butterfly coil and unequal-pitched zigzag coils, can generate ultrasonic bulk waves to detect pipe wall thickness and internal defects, as well as ultrasonic guided waves to detect surface defects in thick-walled pipes or defects in thin-walled pipes throughout their thickness. The ultrasonic guided waves excited by the unequal-pitched zigzag coils have chirp signal characteristics, enabling pulse compression technology, which can improve the signal-to-noise ratio and resolution of the ultrasonic echo signal, thereby improving detection accuracy.

[0030] (3) Existing non-destructive testing and inspection of high-temperature and high-pressure steam pipelines are mostly carried out periodically while the pipeline is shut down. Steam pipelines are usually large in scale and complex in layout, with poor accessibility for inspection. Manual inspection is often used, which is inefficient and has a heavy workload. Moreover, it is difficult to record the process of pipeline wall thickness corrosion thinning rate and defect expansion, which brings great difficulties to periodic inspection and maintenance. This invention proposes to transmit real-time inspection data wirelessly based on wireless technology, so as to realize unmanned and intelligent inspection. This enables remote real-time monitoring of the structural integrity information of key parts of steam pipelines, thereby assessing the remaining life of the pipeline and providing early warning of pipeline rupture. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of the electromagnetic ultrasound online monitoring probe provided in the embodiment of the present invention, wherein (a) is a schematic diagram of the butterfly coil structure, (b) is a schematic diagram of the unequal-pitch tortuous coil structure, and (c) is a schematic diagram of the structure of the electromagnetic ultrasound online monitoring probe.

[0033] Figure 2 This is a schematic diagram of the Chirp pulse compression process provided in an embodiment of the present invention, wherein (a) is a reference signal, (b) is an ultrasonic guided wave signal, and (c) is a pulse compression signal;

[0034] Figure 3 This is a schematic diagram of the electromagnetic ultrasonic online monitoring device and Internet of Things platform for steam pipelines with coating provided in this embodiment of the invention;

[0035] Figure 4 This is a schematic diagram of the excitation receiving circuit structure provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the discharge current of the excitation receiving circuit provided in an embodiment of the present invention;

[0037] Figure 6 This is an installation schematic diagram of the electromagnetic ultrasonic online monitoring device for steam pipelines with a coating layer provided in an embodiment of the present invention, wherein (a) is a schematic diagram of ultrasonic body waves excited by a butterfly coil, and (b) is a schematic diagram of ultrasonic guided waves excited by unequal-pitch tortuous coils. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "center," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element present.

[0040] Example 1

[0041] like Figure 1 As shown in (a), (b), and (c) of the figure, this embodiment provides an electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer, including:

[0042] The butterfly coil 1 is used to pass a DC-like current, or simultaneously pass a DC-like excitation current and a strong pulse excitation current.

[0043] A zigzag coil 2 is disposed below the butterfly coil 1 and is used to pass a strong pulse excitation current; the zigzag coil 2 is a zigzag coil with unequal spacing, and the spacing gradually decreases from the input end to the output end.

[0044] In practice, the electromagnetic ultrasonic online monitoring probe is attached tightly to the outer wall of the working steel pipe of the steam pipeline. A high-temperature resistant lead penetrates the insulation cotton, eliminating the need to remove or damage the insulation layer. This allows for continuous, non-destructive monitoring of permanently installed high-temperature, high-pressure steam pipelines with insulation layers. The probe's excitation and reception of ultrasonic signals are primarily based on the Lorentz force and inverse Lorentz force effects. The working principle is as follows: First, a DC-like excitation current of 100-2000A is passed through the coil to generate a bias magnetic field. After stabilization, a strong pulse excitation current is applied to induce pulsed eddy currents on the surface of the working steel pipe. The interaction between the pulsed eddy currents and the bias magnetic field generated by the DC-like excitation current causes the surface particles of the working steel pipe to experience a Lorentz force, thus generating ultrasonic waves. When the ultrasonic waves encounter defects in the pipeline or reach the bottom of the pipeline, they are reflected back to the pipeline surface. According to the inverse magnetostrictive effect, this causes the metal particles on the pipeline surface to vibrate, inducing a change in the surrounding magnetic field, thereby "inducing" a voltage signal in the coil.

[0045] Specifically, when monitoring the wall thickness of the working steel pipe, a near-DC excitation current is first passed into the butterfly coil 1 to generate a bias magnetic field. After the near-DC excitation current stabilizes, a strong pulse excitation current is simultaneously passed into the butterfly coil 1 to generate ultrasonic body waves on the working steel pipe. The echo signal of the ultrasonic body waves is received through the butterfly coil 1 to detect the wall thickness and internal defects of the working steel pipe. The current in the middle part of the butterfly coil 1 is in the same direction, so its current path is additive. It mainly utilizes the parallel part of the central conductor of the butterfly coil 1 to generate ultrasonic body waves, which has more concentrated ultrasonic body wave energy. It is very suitable for forming a uniform focus at the end of the bar or shaft, and its focusing ability is far superior to other types of coils.

[0046] When monitoring defects in the working steel pipe, a near-DC excitation current is first passed through the butterfly coil 1 to generate a bias magnetic field. After the near-DC excitation current stabilizes, a strong pulse excitation current is simultaneously passed through the zigzag coil 2 to generate ultrasonic guided waves on the working steel pipe. The ultrasonic guided wave echo signal is received through the zigzag coil 2, which is used to detect surface defects in thick-walled working steel pipes or defects in thin-walled working steel pipes throughout their thickness. Furthermore, an unequal-spacing zigzag coil is proposed. This unequal-spacing zigzag coil is an improvement on the equal-spacing zigzag coil, with the spacing gradually decreasing from front to back. In this embodiment, the preferred position of each turn of the unequal-spacing zigzag coil satisfies the following condition: px n 2 +f 0 vx n -nv 2 / 2=0, where p This represents the linear frequency modulation rate of the Chirp signal, that is, the rate at which the transient frequency of the Chirp signal changes with time. f 0 represents the lowest frequency of the Chirp signal. v The speed at which ultrasound propagates in the test piece. x n For the first n The spacing between the coil turns relative to the first coil is n≥2. Compared to conventional equidistant zigzag coils, the ultrasonic guided waves excited by unequal-spacing zigzag coils exhibit chirp signal characteristics, enabling pulse compression technology. The signal-to-noise ratio and spatial resolution of the ultrasonic guided wave echo signal can be improved by increasing the pulse compression ratio, with actual pulse compression ratios of 20 times or higher. This makes them suitable for detecting small defects on pipe surfaces with high detection accuracy. The unequal-spacing zigzag coils fold the conductors back and forth, with adjacent parallel conductors having opposite current directions. This type of coil generates more concentrated guided wave energy with better directivity. Figure 2The diagram illustrates the Chirp pulse compression process. Due to the unequal spacing of the zigzag coils, the generated ultrasonic guided wave exhibits Chirp signal characteristics. This enables Chirp pulse compression technology, which can significantly improve the signal-to-noise ratio and resolution of the ultrasonic echo signal. Figure 2 In the diagram, (a) is the reference signal and (b) is the ultrasonic guided wave signal. By pulse compression of (a) and (b), the signal obtained is shown in (c).

[0047] The electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer provided in this embodiment is a coil-only EMAT probe. It does not require a water-cooling circulation system or a permanent magnet. It can achieve ultrasonic excitation and reception using a single or two coils. The bias magnetic field is generated by simultaneously passing a DC-like excitation current through the coil instead of a permanent magnet. It is not affected by the Curie point and is especially suitable for non-destructive monitoring and detection in high-temperature environments. The probe size is greatly reduced, making it suitable for narrow detection occasions.

[0048] In practice, both the zigzag coil 2 and the butterfly coil 1 are made of high-temperature resistant ceramic-coated silver wire with a wire diameter of 0.05~0.5mm. The number of turns of the zigzag coil 2 varies from 6 to 20, and is an even number; the number of turns of the butterfly coil 1 needs to be determined based on the premise that it can cover the area of ​​the zigzag coil 2, that is, the current-current-in-the-middle part of the butterfly coil 1 covers the entire zigzag coil 2.

[0049] In a preferred embodiment, to avoid the influence of strong heat radiation from the high-temperature and high-pressure steam pipe at the bottom of the probe, in addition to using a coil made of ceramic layer silver wire, a corundum sheet with a thickness of 0.1~0.5mm is provided below the tortuous coil.

[0050] Example 2

[0051] like Figure 3 As shown, this embodiment provides an electromagnetic ultrasonic online monitoring device for steam pipelines with a coating layer, including an AD sampling control module 5, an excitation receiving circuit 4, and an electromagnetic ultrasonic online monitoring probe 3 as described in Embodiment 1, which are connected in sequence.

[0052] The excitation receiving circuit 4 is used to generate a DC-like excitation current and a strong pulse excitation current to pass the DC-like excitation current and the strong pulse excitation current into the butterfly coil 1, or to pass the DC-like excitation current into the butterfly coil 1 and the strong pulse excitation current into the zigzag coil 2; and to detect the detection echo signal received by the butterfly coil 1 or the zigzag coil 2.

[0053] In implementation, the electromagnetic ultrasonic online monitoring probe 3 is attached tightly to the outer wall of the working steel pipe of the steam pipeline. A high-temperature resistant lead penetrates the insulation cotton, eliminating the need to remove or damage the insulation layer. The integrated AD sampling control module 5 and excitation receiving circuit 4 are installed on the outer wall of the outer steel pipe. The excitation receiving circuit 4 is connected to the high-temperature resistant lead, thus enabling continuous non-destructive monitoring of the permanently installed high-temperature, high-pressure steam pipeline with an insulation layer. The AD sampling control module 5 is used to trigger the excitation receiving circuit 4 to generate a DC-like excitation current and a strong pulse excitation current, which are then supplied to the electromagnetic ultrasonic online monitoring probe 3, and to receive the ultrasonic echo signal detected by the excitation receiving circuit 4. In this embodiment, the AD sampling control module 5 consists of an FPGA control module and an AD sampling module connected to it.

[0054] In this embodiment, as Figure 4 As shown, the excitation receiving circuit includes a high-voltage high-pulse excitation module, a low-voltage DC excitation module, an impedance matching module, an echo detection module, and a switching switch. The high-voltage high-pulse excitation module, the low-voltage DC excitation module, the impedance matching module, the echo detection module, and the electromagnetic ultrasonic online monitoring probe 3 (EMAT probe) are all connected to the switching switch. The low-voltage DC excitation module is always connected to the input terminal of the butterfly coil 1 in the electromagnetic ultrasonic online monitoring probe 3, and the impedance matching module and the echo detection module are always connected to the output terminals of the butterfly coil 1 and the zigzag coil 2 in the electromagnetic ultrasonic online monitoring probe 3. When it is necessary to generate ultrasonic guided waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the zigzag coil 2 through the switching switch; when it is necessary to generate ultrasonic body waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the butterfly coil 1 through the switching switch. The FPGA control module supplies 3.3V power to the driver chip in the high-voltage high-pulse excitation module and inputs a low-voltage pulse trigger signal. The driver chip can enhance the power of the trigger signal generated by the FPGA, enabling it to rapidly increase the gate voltage of the MOSFET, thereby quickly turning the MOSFET on / off. The capacitor bank in the high-voltage high-pulse excitation module (with a relatively small capacitance, approximately 100-700nF, for rapid discharge and increased amplitude of the high-pulse excitation current) can transiently charge and discharge under the control of the MOSFET switch, generating an alternating high-excitation current in the EMAT coil. The low-voltage DC-like excitation module is controlled by a switching module containing IBGT for charging and discharging. The capacitor in the low-voltage DC-like excitation module needs a relatively large capacitance, approximately 1000-3000μF, to achieve a relatively long charging and discharging time. The low-voltage DC-like excitation module generates a relatively long-lasting, relatively smooth DC-like excitation current in the coil, which can provide a static bias magnetic field for ultrasonic excitation and reception. Figure 5 The figure shows the discharge current of the excitation receiving circuit, which includes two components: a DC-like excitation current and a strong pulse excitation current.

[0055] The low-voltage DC excitation module is active for a longer duration than the high-voltage pulse excitation module. The high-voltage pulse excitation module is activated only when the DC excitation current in the coil reaches its maximum value (i.e., when the magnetic field generated by the DC current is strongest), ensuring the maximum amplitude of the excited ultrasonic wave. The impedance matching module maximizes the voltage division of this induced electromotive force across the echo detection module, enhancing the amplitude and signal-to-noise ratio of the echo signal. The echo detection module picks up the echo signal and filters and amplifies it. After passing through a filter and amplifier, the signal is then sampled by an AD sampling module controlled by the FPGA control module (e.g., using an AD converter chip AD9280). The AD9280 has a maximum sampling rate of 32 MSPS and a sampling bit width of 8 bits.

[0056] Preferably, the excitation receiving circuit further includes a sampling current module, which is connected to the impedance matching module. The sampling current module samples the current to determine whether the excitation receiving circuit is operating normally.

[0057] Preferably, the system further includes a wireless communication module 6, which is connected to the AD sampling control module 5. After the FPGA control module reads the sampling data from the AD9280, it establishes a TCP connection with the host computer in the same local area wireless network through the wireless communication module 6 (such as an ESP8266 WiFi module) to upload the collected ultrasonic echo signal. The ESP8266 WiFi module uses STA mode as the client, and the wireless router acts as the factory server. The wireless router acting as the factory server can communicate with multiple front-end ESP8266 WiFi modules simultaneously. The detected data is uploaded to the cloud platform 9 and stored in the cloud host server 10 via the factory wireless router 7 and the third-party communication company base station 8 using cloud computing technology. After obtaining the data, the cloud host server 10 presents the results to the user through the client terminal 11 at the request of the client system terminal 11, thereby realizing online location and quantification of defects and online monitoring of pipe wall thickness reduction.

[0058] like Figure 6 The diagram shows the installation of an electromagnetic ultrasonic online monitoring device for a steam pipeline with a protective coating. The electromagnetic ultrasonic online monitoring probe 3 is attached tightly to the outer wall of the working steel pipe 13 of the steam pipeline. The probe penetrates the insulation layer 14 through a high-temperature resistant lead wire. The main chassis 12, which integrates the AD sampling control module 5 and the excitation receiving circuit 4, is installed on the outer wall of the outer steel pipe 15. Figure 6 Figure (a) shows a schematic diagram of ultrasonic waves generated by a butterfly coil for detecting thinning of pipe wall and internal defects. Figure 6 Figure (b) shows a schematic diagram of ultrasonic guided waves generated by unequally spaced tortuous coils to detect defects on the surface of a pipe.

[0059] Example 3

[0060] This embodiment provides a method for online electromagnetic ultrasonic monitoring of coated steam pipelines, based on the online electromagnetic ultrasonic monitoring device for coated steam pipelines as described in Embodiment 2. The steps include:

[0061] The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. When the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the butterfly coil to generate ultrasonic body waves in the pipe under test. The butterfly coil receives the ultrasonic body wave echo signal and transmits it to the AD sampling control module.

[0062] The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. Once the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the zigzag coil to generate ultrasonic guided waves in the pipe under test. The zigzag coil receives the ultrasonic guided wave echo signal and transmits it to the AD sampling control module.

[0063] After the collected data is uploaded, the host computer can perform early warning of pipe wall thickness reduction and defect detection based on the received data.

[0064] The pipe wall thickness reduction early warning process is as follows: The pipe wall thickness at the monitoring point is obtained by analyzing the received ultrasonic body wave echo signal, thus generating a time series of the pipe wall thickness at the monitoring point. A pipe wall thickness reduction early warning algorithm based on gray prediction is then used to monitor and issue early warnings for pipe wall thickness reduction at the monitoring point. Specifically, this includes:

[0065] (1) Calculate the series ratio of the pipe wall thickness time series measured at the monitoring points. λ ( k ),in λ ( k The calculation formula for ) is as follows:

[0066]

[0067] In the formula, This represents time series data of pipe wall thickness. k Indicates the data sequence number in the time series. n This represents the total number of time series data.

[0068] And the level ratio λ ( k Perform a validity test to observe whether all of them fall within the acceptable coverage area. θ Within the range; can accommodate coverage θ The formula for calculating the range is as follows:

[0069]

[0070] (2) If yes, proceed to step (3); if no, perform a translation transformation on the pipe wall thickness time series data with respect to an arbitrary constant C to determine that the series ratios all fall within the range θ.

[0071] (3) Establish gray differential equations and corresponding whitening differential equations for the pipe wall thickness time series data, and calculate the variables in the differential equations using matrix calculations. The specific calculation formulas are as follows:

[0072] Grey differential equation:

[0073]

[0074] In the formula, a , b This indicates that the least squares method is used to make J ( u When the minimum value is reached u The estimated value, express The mean of the generated sequence;

[0075] J ( u The expression for ) is as follows:

[0076]

[0077] in,

[0078] Use the least squares method to find that... The estimated value of u that reaches its minimum:

[0079]

[0080] Whitening differential equation:

[0081]

[0082] in, express The sequence generated by one cumulative iteration;

[0083] The formula for calculating the early warning of pipe wall thickness reduction is as follows:

[0084]

[0085] in, Representing time series data of pipe wall thickness The first data in the data, N It is an equal time interval (i.e., detection cycle). t For pipeline operation time. When the wall thickness... Less than the specified minimum wall thickness When the time comes, the system will automatically issue a warning and remind staff to replace it, thus achieving the purpose of early warning.

[0086] The defect detection process is as follows: Ultrasonic guided wave echo signals from monitoring points are acquired and imaged to form an ultrasonic imaging atlas; the ultrasonic imaging atlas is then input into a pre-trained pipeline defect identification model to obtain the pipeline defect type. The pipeline defect identification model is obtained through the following method: acquiring historical ultrasonic imaging atlases and corresponding defect type labels, constructing a training sample set, building a multi-classification network model based on a deep neural network, and training the multi-classification network model based on the training sample set to obtain the pipeline defect identification model.

[0087] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0088] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer, characterized in that, include: A butterfly coil is used to pass a DC-like current, or simultaneously pass a DC-like excitation current and a strong pulse excitation current; the current in the middle part of the butterfly coil is in the same direction. A zigzag coil is disposed below the butterfly coil and is used to pass a strong pulse excitation current; the zigzag coil is a zigzag coil with unequal spacing, and the spacing gradually decreases from the input end to the output end; The position of each turn of the conductor in the zigzag coil satisfies the following condition: px n 2 +f 0 vx n -nv 2 / 2=0, where p This indicates the linear frequency modulation rate of the Chirp signal. f 0 represents the lowest frequency of the Chirp signal. v The speed at which ultrasound propagates in the test piece. x n For the first n The spacing between the coil and the first coil of wire is n≥2.

2. The electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer according to claim 1, characterized in that, The portion of the butterfly coil with the current in the same direction in the middle covers the entire zigzag coil.

3. The electromagnetic ultrasonic online monitoring probe for steam pipelines with a coating layer according to claim 1, characterized in that, Also includes: A corundum sheet is disposed below the tortuous coil.

4. An electromagnetic ultrasonic online monitoring device for steam pipelines with a coating layer, characterized in that, It includes an AD sampling control module, an excitation receiving circuit, and an electromagnetic ultrasonic online monitoring probe as described in any one of claims 1 to 3, connected in sequence. The excitation receiving circuit is used to generate a DC-like excitation current and a strong pulse excitation current to pass a DC-like excitation current and a strong pulse excitation current into the butterfly coil, or to pass a DC-like excitation current into the butterfly coil and a strong pulse excitation current into the zigzag coil. And a detection echo signal received by the butterfly coil or zigzag coil.

5. The electromagnetic ultrasonic online monitoring device for steam pipelines with coating as described in claim 4, characterized in that, The excitation receiving circuit includes a high-voltage high-pulse excitation module, a low-voltage DC excitation module, an impedance matching module, an echo detection module, and a switching switch. The high-voltage high-pulse excitation module, the low-voltage DC excitation module, the impedance matching module, the echo detection module, and the electromagnetic ultrasonic online monitoring probe are all connected to the switching switch. The low-voltage DC excitation module is always connected to the input terminal of the butterfly coil in the electromagnetic ultrasonic online monitoring probe, and the impedance matching module and the echo detection module are always connected to the output terminals of the butterfly coil and the zigzag coil in the electromagnetic ultrasonic online monitoring probe. When it is necessary to generate ultrasonic guided waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the zigzag coil through the switching switch; when it is necessary to generate ultrasonic body waves in the device under test, the high-voltage high-pulse excitation module is connected to the input terminal of the butterfly coil through the switching switch.

6. The electromagnetic ultrasonic online monitoring device for steam pipelines with coating as described in claim 5, characterized in that, The excitation receiving circuit further includes a sampling current module, which is connected to the impedance matching module.

7. The electromagnetic ultrasonic online monitoring device for steam pipelines with coating as described in claim 4, characterized in that, It also includes a wireless communication module, which is connected to the AD sampling control module.

8. A method for online electromagnetic ultrasonic monitoring of steam pipelines with coating, characterized in that, Based on the electromagnetic ultrasonic online monitoring device for coated steam pipelines as described in any one of claims 4 to 7, the steps include: The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. When the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the butterfly coil to generate ultrasonic body waves in the pipe under test. The butterfly coil receives the ultrasonic body wave echo signal and transmits it to the AD sampling control module. The control excitation receiving circuit supplies a DC-like excitation current into the butterfly coil. Once the DC-like excitation current stabilizes, the control excitation receiving circuit supplies a strong pulse excitation current into the zigzag coil to generate ultrasonic guided waves in the pipe under test. The zigzag coil receives the ultrasonic guided wave echo signal and transmits it to the AD sampling control module.

9. The method for online electromagnetic ultrasonic monitoring of steam pipelines with coating as described in claim 8, characterized in that, Also includes: Obtain the time series of pipe wall thickness at monitoring points, and use a pipe wall thickness reduction early warning algorithm based on gray prediction to monitor and warn of pipe wall thickness reduction at monitoring points; The ultrasonic guided wave echo signal of the monitoring point is acquired and imaged to form an ultrasonic imaging atlas; The ultrasonic imaging atlas is input into a pre-trained pipeline defect identification model to obtain the pipeline defect type; the pipeline defect identification model is obtained by training a deep neural network model based on historical ultrasonic imaging atlases and corresponding defect types.

Images