CN104122329A - Detection sensor based on magnetostriction guide waves, detection system and application - Google Patents

Abstract

The invention discloses a detection sensor based on magnetostrictive guided waves, which comprises: a hollow shell, the center of which is coaxially sleeved with guide rods penetrating through both ends of the hollow shell; a ring magnet, which is built into the shell And coaxially set on the guide rod, which is axially fixed by the magnet positioning plug; the box body is fixed on one end of the guide rod and axially positioned outside the housing through the compression nut, and the excitation plug and the receiving plug are fixedly installed on the on the box body; and a coil bobbin that is sleeved with an exciting coil and a receiving coil, wherein the coil bobbin is fixed on the other end of the guide rod outside the housing, and the exciting coil and the receiving coil are sequentially sleeved on the outer circumference of the coil bobbin and respectively connected to the excitation The plug and the receiving plug are electrically connected. The invention also discloses a system including the detection sensor and its application. The invention only needs the coil skeleton and the part of the excitation receiving coil to be inserted into the heat exchange tube to complete the detection of the entire heat exchange tube, which greatly reduces the area that needs to be cleaned, improves the detection efficiency of the heat exchange tube, and improves the detection efficiency of the heat exchange tube. High precision.

Description

Detection sensor, detection system and application based on magnetostrictive guided wave

technical field

The invention relates to the technical field of ultrasonic non-destructive testing, in particular to a detection sensor based on magnetostrictive guided waves, a detection system including the sensor and its application in detecting defects of heat exchange tubes.

Background technique

With the rapid development of petrochemical, energy and other industries, and the country's increasing emphasis on energy conservation, heat exchangers are playing an increasingly important role in industrial production and daily life. As an important part of the heat exchanger, the number of heat exchange tubes increases geometrically. Due to long-term corrosion and stress, heat exchange tubes often suffer from corrosion, perforation, cracks and other failure forms, resulting in leakage of the conveying medium, which may reduce product quality and cause economic losses, or may endanger society and personal safety. Therefore, regular testing of heat exchange tubes is required.

The characteristic of heat exchange tube testing is that the number of tests is huge, and the sensor can only be placed inside the tube for testing. At present, the detection methods of heat exchange tubes include: magnetic flux leakage detection, far-field eddy current detection, local magnetic saturation eddy current detection, internal rotation ultrasonic phased array detection and ultrasonic guided wave detection methods. Compared with the previous detection methods, the ultrasonic guided wave detection method has the advantage that a single point excitation can detect a certain distance. During the detection process, the sensor does not need to move. On the one hand, it can avoid cleaning the entire pipeline, on the other hand, it improves detection efficiency. Therefore, the ultrasonic guided wave testing method is very suitable for testing heat exchange tubes.

The Chinese invention patent with application number 200480038549.4 discloses a contact torsional wave detection method and system for heat exchange tubes, which discloses that the sensor excites a torsional mode guided wave outside the tube, and the guided wave is coupled to the In the heat exchange tube, this method requires good physical contact between the probe and the inner wall of the heat exchange tube, and the inner wall of the heat exchange tube needs to be polished, which reduces the detection efficiency to a certain extent. The invention patent of patent application number CN201110410262.1 discloses a non-contact magnetostrictive guided wave sensor for heat exchange tube detection, and US patent US7886604B2 discloses a torsional mode electromagnetic ultrasonic sensor for heat exchange tube detection Sensors, both of which place non-contact sensors completely inside the heat exchange tubes to detect the heat exchange tubes. Although the non-contact nature of the sensor reduces the requirements on the condition of the inner surface of the heat exchange tube, only the area where the sensor is placed needs to be cleaned. However, since the sensor is completely placed inside the heat exchange tube, the sensor extends into the heat exchange tube for a long time. This will result in a longer sensor detection blind zone (sensor placement area), and at the same time, higher requirements on the centering and straightness of the sensor will increase the complexity of sensor processing and manufacturing. In addition, the area that needs to be cleaned before detection is still long, which affects the detection efficiency to a certain extent.

Contents of the invention

In view of the above defects, the object of the present invention is to provide a detection sensor based on magnetostrictive guided waves, a detection system including the sensor and its application in the detection of defects in heat exchange tubes, where the magnetized part is placed outside the tube during detection , it only needs to place the sensing coil part inside the pipe near the pipe end, without mechanical contact, and directly excites the longitudinal mode guided wave in the heat exchange pipe, so as to realize the detection of pipe defects. The invention retains the advantages of non-contact detection, reduces the detection blind area, reduces the complexity of sensor processing and manufacturing, further reduces the requirements for cleaning the heat exchange tube, and improves the detection efficiency of the ultrasonic guided wave method for heat exchange tube detection .

According to one aspect of the present invention, a detection sensor based on magnetostrictive guided waves is provided for detection of pipeline defects, characterized in that the detection sensor includes:

A hollow shell, the center of which is coaxially sleeved with guide rods running through both ends of the hollow shell;

An annular magnet, which is housed in the hollow housing and coaxially sleeved on the guide rod, is axially fixed by a magnet positioning plug located at the end of the housing;

A box body, which is fixedly arranged on one end of the guide rod and is located outside the housing, and the excitation plug and the receiving plug are fixedly installed on the box body through a cover plate; and

The coil bobbin with the excitation coil and the receiving coil is sleeved, wherein the coil bobbin is fixed on the other end of the guide rod outside the casing, the excitation coil and the receiving coil are sequentially sleeved on the outer circumference of the coil bobbin and respectively connected to the The excitation plug and the receiving plug are electrically connected;

During the measurement, the coil frame with the excitation coil and the receiving coil inserted into the pipeline, the excitation plug and the receiving plug can generate an axial alternating magnetic field in the pipeline after the excitation plug and the receiving plug are energized. The static magnetic field generated in the heat exchange tube along the axial direction of the tube excites the longitudinal mode guided wave in the tube based on the magnetostrictive effect, and the echo generated by reflection after propagating in the tube can be detected after being processed by the receiving coil Out of the pipeline defect.

As an improvement of the present invention, the guided wave is reflected by defects in the pipeline or at the end of the pipeline, and when the reflected echo passes through the receiving coil, it causes a change in the induced voltage of the receiving coil to generate an electrical signal, and the pipeline can be obtained by processing the electrical signal Test results.

As an improvement of the present invention, the outer diameter of the ring magnet is greater than or equal to the outer diameter of the heat exchange tube to be detected, and the inner diameter of the ring magnet is smaller than or equal to the inner diameter of the heat exchange tube to be detected.

As an improvement of the present invention, both the exciting coil and the receiving coil are solenoid coils.

As an improvement of the present invention, the coil frame is made of insulating material.

As an improvement of the present invention, the guide rod and the casing are made of non-ferromagnetic materials.

According to another aspect of the present invention, there is provided a detection system comprising the above-mentioned detection sensor, which is characterized in that it also includes a power amplifier, a signal generator, a processor, a filter amplifier and an A/D converter electrically connected to the detection sensor in sequence device, wherein the power amplifier is electrically connected to the excitation plug, and the receiving plug is electrically connected to the filter amplifier;

The processor controls the signal generator to generate a sinusoidal pulse current signal, which is amplified by the power amplifier and then input to the detection sensor, thereby exciting the longitudinal mode guided wave in the pipeline, which generates a corresponding wave after propagating and reflecting in the pipeline. An electrical signal, after passing through the filter amplifier and the A/D converter, the electrical signal is input into the processor for analysis and processing to obtain the pipeline defect detection result.

According to another aspect of the present invention, there is provided a method for detecting defects of heat exchange tubes using the detection sensor based on magnetostrictive guided waves, which is characterized in that the method includes:

Insert one end of the detection sensor with the excitation coil and the receiving coil into the heat exchange tube to be detected, and one end of the detection sensor shell is tightly attached to the end surface of the pipe;

The excitation coil is passed an alternating current through the excitation plug, so that the excitation coil generates an axial alternating magnetic field in the heat exchange tube, and the ring magnet therein produces a static magnetic field along the pipe axis in the heat exchange tube based on The magnetostrictive effect excites the longitudinal mode guided wave in the pipeline, which propagates in the pipeline and is reflected by the defects in the pipeline or the end of the pipeline;

The receiving coil receives the reflected echo, and causes the receiving coil to induce a voltage change, thereby generating an electrical signal, which is output to the outside through the receiving plug for processing, so as to detect pipeline defects.

In the present invention, the polarization direction of the ring magnet is along the axial direction of the sensor.

In the present invention, the thickness of the ring magnet is greater than or equal to 10 times the wall thickness of the heat exchange tube to be detected, and the greater the wall thickness of the heat exchange tube to be detected, the greater the thickness of the ring magnet.

In the present invention, when the heat exchange tube detection sensor works, the distance between the exciting coil and the receiving coil and the ring magnet is no more than 50mm.

In general, according to the magnetostrictive guided wave-based heat exchange tube sensor of the present invention, the ring magnet placed at the end of the tube provides a static magnetic field, and the sensing coil placed near the end of the tube provides an alternating magnetic field, directly in the heat exchange The longitudinal mode ultrasonic guided wave is excited in the tube, and there is no physical contact between the sensor and the heat exchange tube during the entire detection process. In addition, because only the coil part of the sensor penetrates less than 50mm into the tube, the length of the sensor extending into the tube is greatly reduced, thereby reducing the detection blind area and shortening the cleaning area, which improves the detection efficiency and applicability while ensuring the detection accuracy. The structure of the sensor is simple and convenient.

Description of drawings

Fig. 1 is a cross-sectional view of a heat exchange tube detection sensor based on magnetostrictive guided waves according to an embodiment of the present invention

Fig. 2 is a schematic diagram of the system when the heat exchange tube sensor is used for heat exchange tube detection according to an embodiment of the present invention

Fig. 3 is used outer diameter 25mm in the specific embodiment, the schematic diagram of the change of pipeline of inner diameter 20mm

FIG. 4 is a waveform diagram of a detection signal obtained by using the detection system shown in FIG. 2 .

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not constitute a conflict with each other.

Referring to FIG. 1 , FIG. 1 is a cross-sectional view of a heat exchange tube detection sensor based on magnetostrictive guided waves according to the present invention. As shown in Figure 1, the heat exchange tube detection sensor 13 based on the magnetostrictive guided wave according to the embodiment of the present invention includes an excitation plug 1, a receiving plug 2, a cover plate 3, a box body 4, a compression nut 5, a guide rod 6. Magnet positioning plug 7 , housing 8 , ring magnet 9 , bobbin 10 , exciting coil 11 and receiving coil 12 .

Wherein, the ring magnet 9 is placed inside the shell 8, and the magnet positioning plug 7 is connected with the shell 8 by screws. The guide rod 6 passes through the shell 8, the magnet and the magnet positioning plug 7. The box body 4 is threadedly connected to one end of the guide rod 6 and fixed by a compression nut 5 . The cover plate 3 and the box body 4 are connected by screws, and the excitation plug 1 and the receiving plug 2 are installed on the cover plate. The coil bobbin 10 is connected to the other end of the guide rod 6 through threads. The exciting coil 11 and the receiving coil 12 are wound on the bobbin 10 and electrically connected to the exciting plug 1 and the receiving plug 2 respectively.

The process of using the heat exchange tube detection sensor according to the embodiment of the present invention to detect the heat exchange tube will be described in detail below with reference to FIG. 2 . As shown in Figure 2, in the detection process to heat exchange tube 14, sensor 13 is installed on the end of heat exchange tube 14, due to the suction force of ring magnet 9 to heat exchange tube 14, the bottom surface of shell 8 and heat exchange tube The ends are snapped together. The relative position of the guide rod and the shell is adjusted so that the bobbin 10, the exciting coil 11 and the receiving coil 12 extend into the tube for a certain distance.

The computer 17 controls the signal generator 16 to generate a sinusoidal pulse current signal. The current signal is amplified by the power amplifier 15 and then input to the exciting coil 11 . The excitation coil generates an axial alternating magnetic field in the pipeline. The ring magnet 9 generates a static magnetic field in the heat exchange tube 14 along the tube axis. The excitation coil 11 generates an axial alternating magnetic field on the inner surface of the heat exchange tube 14 . Based on the magnetostrictive effect, under the action of the axial static magnetic field and the axial alternating magnetic field, the excitation in the pipeline generates a longitudinal mode guided wave, which propagates along the axial direction of the pipeline. After the guided wave is reflected by the defect or the end, when the reflected echo passes through the receiving coil 12, the induced voltage of the receiving coil will be changed to generate an electrical signal. After the electric signal passes through the filter amplifier 19 and the A/D converter 18, it enters the computer acquisition card to complete the whole detection process.

Figure 3 is a schematic diagram of a pipe standard sample with an outer diameter of 25mm and an inner diameter of 20mm. The length of the pipe is 2.8m. There is a transverse groove defect at a position 1.4m from the left end, and a through hole defect at a position 2m from the left end. The transverse groove is 12.5mm long, 1mm wide, and 0.5mm deep, and the equivalent cross-sectional area loss is 3.7%. The diameter of the through hole is Φ5, and its equivalent cross-sectional area loss is 7.5%.

FIG. 4 is a waveform diagram of a signal detected on a standard sample tube by using the heat exchange tube guided wave detection system shown in FIG. 2 . In Fig. 4, the echo of the transverse groove defect is represented by S1, the echo of the through-hole defect is represented by S2, and the echo of the end of the heat exchange tube is represented by S3. It can be seen from the figure that the heat exchange tube detection sensor based on magnetostrictive guided waves can detect transverse groove defects and through hole defects with good detection accuracy.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included within the scope of the present invention . For example, a permanent magnet is placed at the end of the cable to magnetize the cable in the axial direction, and two solenoid coils are wound on the outside of the cable close to the end, which are used as the excitation coil and the receiving coil respectively, which can excite Longitudinal mode ultrasonic guided wave is used to detect the anchorage area of the cable.

Claims (8)

1. the detecting sensor based on magnetic striction wave guide, the detection for defect of pipeline, is characterized in that, this detecting sensor comprises:

Hollow housing (8), its center coaxial sleeve is connected to the guide rod (6) that runs through this hollow housing (8) two ends;

Ring-shaped magnet (9), it is placed in, and in described hollow housing (8), also coaxial package is upper at described guide rod (6), and it is by being positioned at magnet restricted plug (7) axial restraint of housing (8) end;

Casing (4), it is fixedly installed on described guide rod (6) one end and is positioned at outside described housing (8), and described excitation plug (1) and reception plug (2) are fixedly mounted on this casing (4) by cover plate (3);

And

Be socketed with the coil rack (10) of drive coil (11) and receiving coil (12), wherein said coil rack (10) is fixed on being positioned on the other end outside housing of described guide rod (6), and described drive coil (11) and receiving coil (12) are enclosed within successively described coil rack (10) periphery and are electrically connected to described excitation plug (1) and reception plug (2) respectively;

The coil rack (10) that is socketed with drive coil (11) and receiving coil (12) during measurement stretches in pipeline, after described excitation plug (1) and reception plug (2) energising, can make described drive coil (11) in pipeline, produce axial alternating magnetic field, and produce along the static magnetic field of pipeline axial and in pipeline, motivate longitudinal mode guided wave based on magnetostrictive effect in pipeline (14) with described ring-shaped magnet (9), it can detect defect of pipeline at the echo of propagating back reflection generation in pipeline after described receiving coil is processed.

2. a kind of detecting sensor based on magnetic striction wave guide according to claim 1, is characterized in that, described ring-shaped magnet polarised direction along sensor axis to.

3. a kind of detecting sensor based on magnetic striction wave guide according to claim 1 and 2, wherein, described ring-shaped magnet (9) external diameter is more than or equal to pipeline to be detected (14) external diameter, and ring-shaped magnet (9) internal diameter is less than or equal to pipeline to be detected (14) internal diameter.

4. according to a kind of detecting sensor based on magnetic striction wave guide described in any one in claim 1-3, wherein, described drive coil (11) and receiving coil (12) are solenoid coil.

5. according to a kind of detecting sensor based on magnetic striction wave guide described in any one in claim 1-4, wherein, described coil rack (10) is made by insulating material.

6. according to a kind of detecting sensor based on magnetic striction wave guide described in any one in claim 1-5, wherein, described guide rod (6) and shell (8) are made by nonferromugnetic material.

7. a detection system that comprises the detecting sensor described in any one in claim 1-6, it is characterized in that, also comprise the power amplifier (15), signal generator (16), processor (17), filter amplifier (19) and the A/D converter (18) that are electrically connected to successively with this detecting sensor, wherein, described power amplifier (15) is electrically connected to described excitation plug, and described reception plug is electrically connected to described filter amplifier (19);

Described processor (17) control signal generator (16) produces sinusoidal pulse current signal, after power amplifier (15) amplifies, be input to described detecting sensor, thereby and excitation produces longitudinal mode guided wave in pipeline, after propagating and reflecting, produce corresponding electric signal in pipeline, this electric signal, after described filter amplifier (19) and A/D converter (18), is inputted described processor (17) and is processed and can obtain defect inspection result by analysis.

8. utilize the method that in the claims 1-6, the detecting sensor heat exchanging defective tube based on magnetic striction wave guide described in any one detects, it is characterized in that, the method comprises:

By one end with drive coil (11) and receiving coil (12) of described detecting sensor, from inserting in heat exchanger tube pipeline to be detected (14), and the housing of described detecting sensor (8) one end and pipeline end face are adjacent to;

By excitation plug (1), drive coil (11) is passed to exchange current, thereby make described drive coil (11) in heat exchanger tube (14), produce axial alternating magnetic field, and produce along the static magnetic field of pipeline axial and in pipeline, motivate longitudinal mode guided wave based on magnetostrictive effect in heat exchanger tube (14) with ring-shaped magnet (9) wherein, it propagates and defect or pipe end reflection in pipeline in pipeline;

Described receiving coil (12) receives described reflection echo, and described receiving coil (12) induced voltage is changed, thereby generation electric signal, this electric signal outputs to outside by described reception plug (2) and processes, and can detect defect of pipeline.