CN107941905A - A kind of low frequency array eddy current testing device and steel pipe inner wall corrosion default detection method - Google Patents
A kind of low frequency array eddy current testing device and steel pipe inner wall corrosion default detection method Download PDFInfo
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- CN107941905A CN107941905A CN201810025874.0A CN201810025874A CN107941905A CN 107941905 A CN107941905 A CN 107941905A CN 201810025874 A CN201810025874 A CN 201810025874A CN 107941905 A CN107941905 A CN 107941905A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
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Abstract
The present invention relates to a kind of low frequency array eddy current testing device and steel pipe inner wall corrosion default detection method, technical solution to be, including EDDY CURRENT host, connecting line and low frequency array eddy current probe；EDDY CURRENT host is connected by connecting line with low frequency array eddy current probe, display is respectively provided with host shell, probe connection socket, low-frequency oscillator is respectively provided with housing, lithium battery, controller, amplifier, balance filter, phase shifter, gain adjustable amplifier and digital analog converter, the present invention eliminates the interference of space scattering leakage magnetic flux by the shielding techniques of magnetic tank and shielded coil, improve Defect resolution, 8 detection coils can independent imaging in detection process, and detection sensitivity is always consistent, avoid defect missing inspection, once-through operation can detection probe covering heating surface tube inner wall defect, without reciprocating operation, it is easy to use, effect is good.
Description
Technical field
The present invention relates to electric system heating surface tubes in boilers eddy detection technology field, especially a kind of low frequency array vortex inspection
Survey device and steel pipe inner wall corrosion default detection method.
Background technology
Power Station Boiler Heating Surface pipe is chronically at the working environment of high temperature and pressure, its tubing surfaces externally and internally easily produces corrosion
Abrasion, hydrogen damage, corrode the defects of point, oxidation pit, crackle, flue gas corrosion, etch pit, and the continuous development of defect causes to let out
Leak, the safe operation of serious threat unit, cause the unplanned outage of unit.Therefore, inner wall is inspected periodically to heating surface tube
Corrosion condition is the effective means for preventing accident from occurring.By detection, heating surface tube use state can be evaluated, estimation uses the longevity
Life, Rational Change pipe row, reduces unplanned property machine stop times, reduces unit operation cost.
At present, heating surface tube inner wall corrosion detection has benefited from low frequency pipe corrosion scanning instrument, but the instrument probe is main
It is made of monomer coil, it is simple in structure, the effective overlay area of coil is limited, to the pipe defect resolution in fiery side centre
It is higher with accuracy of detection, and the detection sensitivity of both sides of the edge then declines successively, easily causes missing inspection, and due in its structure
Problem, there are inconvenience during use, therefore, it is imperative that it improves and innovates.
The content of the invention
For the above situation, to overcome the defect of the prior art, the purpose of the present invention is just to provide a kind of low frequency array whirlpool
Flow detection device, can effectively solve the problems, such as boiler heating surface defects detection.
The technical solution that the present invention solves is：
A kind of low frequency array eddy current testing device, the detection device include EDDY CURRENT host, connecting line and low frequency array vortex
Probe；EDDY CURRENT host is connected by connecting line with low frequency array eddy current probe；
The EDDY CURRENT host includes host shell, display is respectively provided with host shell, connection socket of popping one's head in, in housing
It is respectively provided with low-frequency oscillator, lithium battery, controller, amplifier, balance filter, phase shifter, gain adjustable amplifier sum number
Mode converter, the output terminal of lithium battery are connected with the input terminal of low-frequency oscillator, the output terminal of low-frequency oscillator and controller
Input terminal is connected, and the output terminal of controller is connected with probe connection socket, the input of probe connection socket and low-noise amplifier
End is connected, balance filter, phase shifter, gain adjustable amplifier, the digital analog converter that the output terminal of noise amplifier is concatenated
It is connected with the input terminal of controller, the output terminal of controller is connected with display；
The probe connection socket is connected by connecting line with the probe socket of low frequency array eddy current probe；
The connecting line includes connecting line body, and connecting line body includes total shielding braid net and is wrapped in total shielding braid net
Interior vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line and power cord, vortex collection signal
Transmission line, excited oscillation transmission line, location coding signal transmssion line and power cord are sub-thread shielding braid net and are wrapped in list
What the cored wire in stock shielding braid net was formed, the both ends of connecting line body are respectively arranged with the probe with low frequency array eddy current probe
Socket connects the corresponding aviation plug of socket with the probe of EDDY CURRENT host, is respectively arranged with aviation plug and is adopted with vortex
Collect signal transmssion line, excited oscillation transmission line, location coding signal transmssion line, the one-to-one contact pin of power cord, corresponding transmission
The cored wire end of line is connected with the rear end of corresponding contact pin.
The low frequency array eddy current probe includes housing, and housing is hollow structure, and the bottom plate section of housing is in concave up
Arc surfaced, the both sides of bottom plate are provided with guiding rubber tire, circumferentially equal along the arc surfaced of same radial section on bottom plate in housing
It is furnished with multiple detection coils, the outer cover of detection coil is equipped with the magnetic tank for being used for eliminating space scattering leakage magnetic flux, on the outside of magnetic tank
Magnet exciting coil is provided with housing, the shielded coil for focusing magnetic circuit, housing are provided between magnet exciting coil and detection coil
Amplifier is inside provided with, shell one end is provided with the encoder for synchronous recording detection data, and hull outside is provided with and navigates
The probe socket of blind plug connection, each detection coil output terminal are connected with the input terminal of amplifier respectively, the output of amplifier
The output terminal at end, the input terminal of magnet exciting coil and encoder is connected with probe socket.
A kind of ferromagnetic steel pipe inner wall corrosion defect inspection method using low frequency array eddy current testing device, including it is following
Step：
A, abandoned tender standard is sentenced to detection and is demarcated
Sensitivity comparison test tube is processed first, same batch heating surface pipe is taken, is splitted along tube center, successively in tube wall week
To at interval of 20 ° of positions, 4 a diameter of Φ 6mm of equally spaced axially processing, the artificial defect that hole depth is 20% design wall thickness
Blind hole, is scanned detection, with detection sensitivity to having a competition by low frequency array eddy current testing device to Sensitivity comparison test tube
The P-T of artificial defect on pipe（Phase-shift phase-time）The depth value of scanning curve amplitude standardization defect, and sentence abandoned tender as detection
Standard, sets the percentage of the shared wall thickness of the digital baseband input signal of the scanning signal, depth and defect, exceedes in checkout procedure
The defects of amplitude, should carry out sentencing useless processing；
During Scanning Detction, two groups of guiding rubber tires are close to the surface of Sensitivity comparison test tube, promote probe to be detected manually, when
The magnet exciting coil of alternating current is loaded with close to when contrasting test tube made of conductive magneto-conductive steel pipe, due to the effect of coil magnetic field,
Vortex can be generated in conductive magneto-conductive steel pipe, size, phase and the liquid form of vortex are influenced by conductive material performance, and whirlpool
The raw counter magnetic field of miscarriage makes the impedance of detection coil change again, and vortex is shown in after amplifier signal enhanced processing
In the display for detecting host；The P-T scanning curves are vortex phase shift amount time history plot picture；
B, defect location
Two groups of guiding rubber tires are close to the surface of steel pipe to be measured, promote probe to be detected manually, to be swept less than 3~5 ms/min
Look into speed uniform scanning and be tested tube outer surface；Electric current is sent into probe by connecting line by controller after low-frequency oscillator is handled and is swashed
Coil is encouraged, magnetic flux caused by excitation coil covers 8 detection coils, and amplifies each detection line by 8 passage preamplifiers
Circle collection signal, and EDDY CURRENT host is transmitted to through connecting line, when tested heating surface tube zero defect, then the leakage of space scattering
Magnetic flux balance and symmetry, each detection coil output is zero, and when tested heating surface tube is defective, defect disturbs magnetic flux and vortex field
It is dynamic leakage magnetic flux asymmetric distribution is occurred, thus the detection coil in defect can produce unbalanced signal, unbalanced signal is through low noise
After amplifier amplification, then filtered through balance filter and be placed in reference " zero " level with automatic digital formula electronic equilibrium, Jiang Gexian, filtered
Ripple device and self balancing time constant are set by controller, filter and balance after the defects of signal respectively enter phase shifter and
Gain adjustable amplifier carries out phase angle fixation and signal amplification, and controller is sent into digital signal through analog-to-digital conversion after amplification,
And show over the display, realize the positioning of defective locations：
1）Defect is circumferentially positioned
Inner wall defect detection is carried out to heating surface tubes in boilers by low frequency array eddy current probe, probe can cover tested 125 ° of tube wall
Scope, the P-T scanning curves of each detection coil are independently presented and corresponding with coil array position, when probe is by defective
Tube wall when, corresponding detection coil will cut the magnetic line of force drained to outside tube wall and induce a maximum voltage signal, should
The impedance of coil can also change and be presented on P-T scanning curves, so that it is determined that the circumferential position of defect, and lacked to circumferential
It is trapped into capable record；
2）Defect axially position
If being found in detection process, defect needs to store detection data, can select external trigger, that is, the arteries and veins for upper encoder of popping one's head in
Signal triggering is rushed, P-T scanning curves are synchronous with probe scanning detection at this time, and scanning detects probe forward, and P-T scanning curves are synchronous
Rolls forward is shown, is shown the distance that probe scanning detection is passed by screen at the same time, is needed to check when running into defect, probe is back
Scanning detects, then erasing in real time retreats the equidistant P-T scanning curves distance passed by with probe on screen, so that it is determined that lacking
Sunken axial location, and axial flaw is recorded；
C, defect is checked
It will locate surface the defects of positioning and remove totally, and coat couplant, with sonigauge repetition measurement, to confirm depth of defect,
Tube surface geometry is irregular, butt weld, and pipe bent position, pipe end and internal stress may can all be brought tired to defect estimation
Disturb, therefore, detection final result is subject to sonigauge and is checked；
D, verified once with Sensitivity comparison test tube when 2 is small, if people's industrial injury is difficult to distinguish on Sensitivity comparison test tube, it
Preceding detection is invalid.
Low frequency array eddy current testing device structure novel and unique of the present invention, advantages of simple, easily production, easy to operate, cost is low,
Tested 125 ° of circumferential areas of heating surface tube can effectively be covered using the detection probe of 8 along the circumferential direction arrays, and pass through magnetic tank
The interference of space scattering leakage magnetic flux is eliminated with the shielding techniques of shielded coil, Defect resolution is improved, 8 in detection process
A detection coil can independent imaging, and detection sensitivity is always consistent, avoids defect missing inspection, and once-through operation can be examined
The heating surface tube inner wall defect of probing head covering, without reciprocating operation, detection data have by data encoder synchronous recording
Analysis is called beneficial to detection data and is achieved, and improves detection efficiency, preposition amplifier is set in probe, first puts signal
Greatly, the decay with offseting signal in transmitting procedure, will freeze that zeroing switches are preposition, eliminate the puzzlement of time difference, baseline deviation
During zero point, zero can be adjusted in time；It can effectively solve the problems, such as the positioning of Power Station Boiler Heating Surface inside pipe wall corrosion default, improve
Accuracy of detection and work on the spot efficiency, have ensured the reliable and stable operation of Power Station Boiler Heating Surface pipe, and easy to use, effect is good,
There is good social and economic benefit.
Brief description of the drawings
Fig. 1 is the stereogram of EDDY CURRENT host shell of the present invention.
Fig. 2 is the left view of EDDY CURRENT host shell of the present invention.
Fig. 3 is the partial front elevation view of connecting line of the present invention.
Fig. 4 is the part section front view of connecting line body of the present invention.
Fig. 5 is the cross sectional side view of connecting line body of the present invention.
Fig. 6 is the sectional front view of low frequency array eddy current probe use state of the present invention.
Fig. 7 is the right view of low frequency array eddy current probe use state of the present invention.
Fig. 8 is the cross sectional side view of low frequency array eddy current probe use state of the present invention
Fig. 9 is circuit theory frame schematic diagram of the present invention.
Embodiment
The embodiment of the present invention is described in further detail below in conjunction with attached drawing.
Provided by Fig. 1-9, a kind of low frequency array eddy current testing device, which includes EDDY CURRENT host, connection
Line and low frequency array eddy current probe；EDDY CURRENT host is connected by connecting line with low frequency array eddy current probe；
The EDDY CURRENT host includes host shell 19, and display 20, probe connection socket 24 are respectively provided with host shell,
Low-frequency oscillator, lithium battery, controller, amplifier, balance filter, phase shifter, adjustable gain is respectively provided with housing 19 to put
Big device and digital analog converter, the output terminal of lithium battery are connected with the input terminal of low-frequency oscillator, the output terminal of low-frequency oscillator with
The input terminal of controller is connected, and the output terminal of controller is connected with probe connection socket 24, probe connection socket 24 and low noise
The input terminal of amplifier is connected, and balance filter, phase shifter, the adjustable gain that the output terminal of noise amplifier is concatenated amplify
Device, digital analog converter are connected with the input terminal of controller, and the output terminal of controller is connected with display 20；
The probe connection socket 24 is connected by connecting line with the probe socket 2 of low frequency array eddy current probe；
The connecting line includes connecting line body 13, and connecting line body 13 includes total shielding braid net 131 and is wrapped in total screen
Vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line and the power cord in mesh grid 131 are covered,
Vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line and power cord are sub-thread shielding braid
What net 132 and the cored wire 133 being wrapped in sub-thread shielding braid net 132 were formed, the both ends of connecting line body 13 are respectively arranged with
The corresponding aviation plug 14 of socket is connected with the probe socket of low frequency array eddy current probe and the probe of EDDY CURRENT host, is navigated
It is respectively arranged with blind plug 14 and vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line, electricity
The one-to-one contact pin 18 of source line, the cored wire end of corresponding transmission line are connected with the rear end of corresponding contact pin.
The low frequency array eddy current probe includes housing 1, and housing 1 is hollow structure, the bottom plate 1a sections of housing 1 be in
The arc surfaced of fovea superior, the both sides of bottom plate 1a, which are provided with, is oriented to rubber tire 4, in housing 1, along the arc of same radial section on bottom plate 1a
Face shape is circumferentially evenly equipped with multiple detection coils 11, and the outer cover of detection coil 11 is equipped with the magnetic for being used for eliminating space scattering leakage magnetic flux
Tank 10, is provided with magnet exciting coil 7 in the housing 1 in the outside of magnetic tank 10, is provided between magnet exciting coil 7 and detection coil 11 for gathering
The shielded coil 9 of burnt magnetic circuit, amplifier 12 is provided with housing 1, and 1 one end of housing is provided with for synchronous recording detection data
Encoder 8, is provided with the probe socket 2 being connected with aviation plug outside housing 1, each 11 output terminal of detection coil is respectively with putting
The input terminal of big device 12 is connected, the output terminal of the output terminal of amplifier 12, the input terminal of magnet exciting coil 7 and encoder 8 with spy
Connector 2 is connected.
To ensure using effect, the radian of the bottom plate 1a is 2 π/3, and detection coil 11 has uniformly distributed 8, vortex collection
Signal transmssion line has 8 one-to-one with detection coil.
The digital knob 21 being connected with controller, power switch 22, charging socket 23, USB are respectively provided with the housing
Interface 25, grounding receptacle 26 and RS-232 printer interfaces 27, the display are touch-screen, and digital knob 21, which is used to adjust, to be increased
The yield value of beneficial adjustable amplifier, i.e. instrumental sensitivity are manually adjustable in the range of 0.01~15.00 °/div.It is big when needing
When scope changes sensitivity, adjusted by touch-screen.
The top of housing 1 is provided with handle 3, facilitates hand-held；The guiding rubber tire 4 has 4, sets two-by-two respectively
In the both sides of Housing Base, the lower face of housing is stretched out in the bottom for being oriented to rubber tire, and in downwards, sloping inwardly is set, can be with
The tube wall of steel pipe 5 to be measured is bonded completely, can also increase the function of telescopic adjustment, easy to improve system stability；
The encoder 8 is installed on the afterbody of housing, and can install torsional spring, ensures to walk in housing using torsional spring elastic compression
During tube wall all the time with steel pipe 5 to be measured contact, to the distance of collection array scanning probe axial direction scanning in real time, synchronous note
Record detection data, easy to data post processing, achieve.
Be provided with the housing 1 be connected with probe socket 2 freeze zeroing switches 6, when abnormal signal occurs in instrument, freeze
Zeroing switches are tied with lock-screen image to further look to judge.Conventional instrument operator is so usual that first to shelve
Probe, then presses instrument freeze button again, since instrument phase-shifted sweep curve was rolled with the time, thus by generation time
Difference, it is difficult to detection signal is captured in time, instrument detection signal-freeze zeroing switches are preposition, outside low frequency array scanning probe
Being set on shell can freeze to be suspected to be signal immediately, eliminate the puzzlement of time difference.In addition, scanning detection process, depending on field conditions meeting
There are various interference, so that baseline deviation zero point, need to adjust zero in time.Obviously, it is infeasible to shelve probe come operation of returning to zero
's.It is difficult to carry out zeroing operation again in the case where keeping probe state.Instrument zeroing switches are preposition, outside low frequency array scanning probe
Zeroing switches are set on shell, and zeroing operation is just handy.
The magnetic tank 10 is made of magnetic ferrites, each magnetic tank cover with its one-to-one detection coil, by covering
The magnetic tank of lid detection coil carries out magnetic screen, and magnetic ferrites has high magnetic permeability, using magnetic circuit shunting principle to low frequency electromagnetic field into
Row shielding, eliminates the interference of the leakage magnetic flux of space scattering, improves Defect resolution, 8 detection coils are equal in detection process
Can independent imaging, and detection sensitivity is always consistent, avoids defect missing inspection.
The controller includes model stm32f103 (mpu) microcontrollers and ep4ce10e22 (fpga) programmable logic
Controller.
Total shielding braid net 131 and sub-thread shielding braid net 132 is made of nylon mesh grid.
A kind of ferromagnetic steel pipe inner wall corrosion defect inspection method using the low frequency array eddy current testing device, including
Following steps：
A, abandoned tender standard is sentenced to detection and is demarcated
Sensitivity comparison test tube is processed first, same batch heating surface pipe is taken, is splitted along tube center, successively in tube wall week
To at interval of 20 ° of positions, 4 a diameter of Φ 6mm of equally spaced axially processing, the artificial defect that hole depth is 20% design wall thickness
Blind hole, is scanned detection, with detection sensitivity to having a competition by low frequency array eddy current testing device to Sensitivity comparison test tube
The P-T of artificial defect on pipe（Phase-shift phase-time）The depth value of scanning curve amplitude standardization defect, and sentence abandoned tender as detection
Standard, sets the percentage of the shared wall thickness of the digital baseband input signal of the scanning signal, depth and defect, exceedes in checkout procedure
The defects of amplitude, should carry out sentencing useless processing；
During Scanning Detction, two groups of guiding rubber tires are close to the surface of Sensitivity comparison test tube, promote probe to be detected manually, when
The magnet exciting coil of alternating current is loaded with close to when contrasting test tube made of conductive magneto-conductive steel pipe, due to the effect of coil magnetic field,
Vortex can be generated in conductive magneto-conductive steel pipe, size, phase and the liquid form of vortex are influenced by conductive material performance, and whirlpool
The raw counter magnetic field of miscarriage makes the impedance of detection coil change again, and vortex is shown in after amplifier signal enhanced processing
In the display for detecting host；The P-T scanning curves are vortex phase shift amount time history plot picture；
B, defect location
Two groups of guiding rubber tires are close to the surface of steel pipe 5 to be measured, promote probe to be detected manually, with less than 3~5 ms/min
Scanning speed uniform scanning is tested tube outer surface；Electric current is sent into by connecting line by controller after low-frequency oscillator is handled and popped one's head in
Excitation coil, magnetic flux caused by excitation coil covers 8 detection coils, and amplifies each detection by 8 passage preamplifiers
Coil gathers signal, and be transmitted to EDDY CURRENT host through connecting line, when tested heating surface tube zero defect, then space scattering
Leakage magnetic flux balance and symmetry, the output of each detection coil is zero, and when tested heating surface tube is defective, defect is to magnetic flux and vortex field
Disturbance makes leakage magnetic flux asymmetric distribution occur, thus the detection coil in defect can produce unbalanced signal, and unbalanced signal is through low noise
After acoustic amplifier amplification, then filtered through balance filter and be placed in reference " zero " level with automatic digital formula electronic equilibrium, Jiang Gexian,
Wave filter and self balancing time constant are set by controller, filter and balance after the defects of signal respectively enter phase shifter
Phase angle fixation and signal amplification are carried out with gain adjustable amplifier, is sent into and controls into digital signal through analog-to-digital conversion after amplification
Device, and show over the display, realize the positioning of defective locations：
1）Defect is circumferentially positioned
Inner wall defect detection is carried out to heating surface tubes in boilers by low frequency array eddy current probe, probe can cover tested 120 ° of tube wall
Scope, the P-T scanning curves of each detection coil are independently presented and corresponding with coil array position, when probe is by defective
Tube wall when, corresponding detection coil will cut the magnetic line of force drained to outside tube wall and induce a maximum voltage signal, should
The impedance of coil can also change and be presented on P-T scanning curves, so that it is determined that the circumferential position of defect, and lacked to circumferential
It is trapped into capable record；
2）Defect axially position
If being found in detection process, defect needs to store detection data, can select external trigger, that is, the arteries and veins for upper encoder of popping one's head in
Signal triggering is rushed, P-T scanning curves are synchronous with probe scanning detection at this time, and scanning detects probe forward, and P-T scanning curves are synchronous
Rolls forward is shown, is shown the distance that probe scanning detection is passed by screen at the same time, is needed to check when running into defect, probe is back
Scanning detects, then erasing in real time retreats the equidistant P-T scanning curves distance passed by with probe on screen, so that it is determined that lacking
Sunken axial location, and axial flaw is recorded；
C, defect is checked
It will locate surface the defects of positioning and remove totally, and coat couplant, with sonigauge repetition measurement, to confirm depth of defect,
Tube surface geometry is irregular, butt weld, and pipe bent position, pipe end and internal stress may can all be brought tired to defect estimation
Disturb, therefore, detection final result is subject to sonigauge and is checked；
D, verified once with Sensitivity comparison test tube when 2 is small, if people's industrial injury is difficult to distinguish on Sensitivity comparison test tube, it
Preceding detection is invalid.
By the above situation it should be apparent that low frequency array eddy current testing device structure novel and unique of the present invention, simply
Rationally, easily production, easy to operate, cost is low, and electric current is sent into probe by connecting line by controller after low-frequency oscillator is handled and is swashed
Coil is encouraged, due to adding low-frequency oscillator, frequency range is maintained at 1Hz~2000Hz, minimum step value is 0.1Hz, frequency
The wall thickness of the lower detection of rate is deeper, and magnetic flux caused by excitation coil covers 8 detection coils, and by being put before 8 passages
Big device amplifies each detection coil collection signal, and is transmitted to EDDY CURRENT host through connecting line, when tested heating surface tube zero defect
When, then the leakage magnetic flux balance and symmetry of space scattering, each detection coil output is zero, when tested heating surface tube is defective, defect
Disturbance to magnetic flux and vortex field makes leakage magnetic flux asymmetric distribution occur, thus the detection coil in defect can produce unbalance letter
Number, unbalanced signal filters and automatic digital formula electronic equilibrium, Jiang Gexian after low-noise amplifier amplifies, then through balance filter
Be placed in reference " zero " level, wave filter and self balancing time constant are set by controller, filter and balance after the defects of
Signal, which respectively enters phase shifter and gain adjustable amplifier, to carry out phase angle and fixes and signal amplification, after amplification through analog-to-digital conversion into
Digital signal is sent into controller, and realizes Three-dimensional Display and data analysis function；Advised by the impedance variations for measuring detection coil
Rule can determine that there is zero defect in material；Decoders-Synchronous recording detection data, a scanning can detection probe area coverages
Under tube wall quality, since each detection coil sensitivity under area of effective coverage is impartial, effectively control defect omission factor,
Detection efficiency is improved, magnetic tank is made of the magnetic ferrites material of high permeability, can effectively eliminate the leakage magnetic flux of space scattering；Screen
Cover coil to be arranged on the outside of magnetic tank, for limiting, focusing magnetic circuit and led to detection coil；Excitation coil and detection coil it
Between form two kinds of orthogonal electromagnetic field transfer modes, be conducive to find to be orientated different line defect；The signal of each coil
Incoming instrument can be separated, effectively avoids the mutual inductance between different coils, using the detection probe of 8 along the circumferential direction arrays
Tested 125 ° of circumferential areas of heating surface tube can be effectively covered, and eliminates space by the shielding techniques of magnetic tank and shielded coil and dissipates
Penetrate the interference of leakage magnetic flux, improve Defect resolution, in detection process 8 detection coils can independent imaging, and detect spirit
Sensitivity is always consistent, avoids defect missing inspection, once-through operation can detection probe covering heating surface tube inner wall defect,
Without reciprocating operation, detection data are conducive to detection data and call analysis and achieve, improved by data encoder synchronous recording
Detection efficiency, pop one's head in preposition amplifier is set, first signal is amplified, places decay of the signal in transmitting procedure, will
Freeze that zeroing switches are preposition, eliminate the puzzlement of time difference, during baseline deviation zero point, zero can be adjusted in time；Including 8 passages
Vortex collection signal transmssion line and excited oscillation transmission line, location coding signal transmssion line and power cord, end are equipped with 24 pins
Aviation plug, convenient connection, shield effectiveness is good, and impedance matching coincide, stable signal transmission, lossless, and low-frequency oscillator makes
Frequency range is maintained at 1Hz~2000Hz, and minimum step value is 0.1Hz, and the wall thickness of the lower detection of frequency is deeper, so as to
Pipe detection for different wall；8 detection coils can independent imaging, and detection sensitivity is always consistent, avoids
Defect missing inspection, once-through operation can detection probe covering heating surface tube inner wall defect, without reciprocating operation, improve inspection
Survey efficiency；Display advantage is imaged using low frequency array eddy current probe scan image, can effectively be solved in Power Station Boiler Heating Surface pipe
The problem of positioning of wall erosion defect, accuracy of detection and work on the spot efficiency are improved, ensured that Power Station Boiler Heating Surface pipe can
Easy to use by stable operation, effect is good, there is good social and economic benefit.
Claims (9)
- A kind of 1. low frequency array eddy current testing device, it is characterised in that the detection device include EDDY CURRENT host, connecting line and Low frequency array eddy current probe；EDDY CURRENT host is connected by connecting line with low frequency array eddy current probe；The EDDY CURRENT host includes host shell（19）, display is respectively provided with host shell（20）, probe connection insert Seat（24）, housing（19）Inside it is respectively provided with low-frequency oscillator, lithium battery, controller, amplifier, balance filter, phase shifter, increasing Beneficial adjustable amplifier and digital analog converter, the output terminal of lithium battery are connected with the input terminal of low-frequency oscillator, low-frequency oscillator Output terminal is connected with the input terminal of controller, output terminal and the probe connection socket of controller（24）It is connected, probe connection socket （24）It is connected with the input terminal of low-noise amplifier, balance filter that the output terminal of noise amplifier is concatenated, phase shifter, increasing Beneficial adjustable amplifier, digital analog converter are connected with the input terminal of controller, the output terminal and display of controller（20）It is connected；The probe connection socket（24）Pass through connecting line and the probe socket of low frequency array eddy current probe（2）It is connected；The connecting line includes connecting line body（13）, connecting line body（13）Including total shielding braid net（131）And parcel In total shielding braid net（131）Interior vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line and Power cord, vortex collection signal transmssion line, excited oscillation transmission line, location coding signal transmssion line and power cord are sub-thread screen Cover mesh grid（132）Be wrapped in sub-thread shielding braid net（132）Interior cored wire（133）Form, connecting line body（13）'s Both ends are respectively arranged with corresponding with the probe of the probe socket of low frequency array eddy current probe and EDDY CURRENT host connection socket Aviation plug（14）, aviation plug（14）On be respectively arranged with and vortex collection signal transmssion line, excited oscillation transmission line, fixed Position encoded signal transmission line, the one-to-one contact pin of power cord（18）, the cored wire end of corresponding transmission line with after corresponding contact pin End is connected;The low frequency array eddy current probe includes housing（1）, housing（1）For hollow structure, housing（1）Bottom plate（1a）Section In concave up arc surfaced, bottom plate（1a）Both sides be provided with guiding rubber tire（4）, housing（1）It is interior, in bottom plate（1a）On along same The arc surfaced of radial section is circumferentially evenly equipped with multiple detection coils（11）, detection coil（11）Outer cover be equipped be used for eliminate sky Between scatter leakage magnetic flux magnetic tank（10）, magnetic tank（10）The housing in outside（1）Inside it is provided with magnet exciting coil（7）, magnet exciting coil（7）With Detection coil（11）Between be provided with shielded coil for focusing magnetic circuit（9）, housing（1）Inside it is provided with amplifier（12）, shell Body（1）One end is provided with the encoder for synchronous recording detection data（8）, housing（1）Outside is provided with to be connected with aviation plug The probe socket connect（2）, each detection coil（11）Output terminal respectively with amplifier（12）Input terminal be connected, amplifier（12） Output terminal, magnet exciting coil（7）Input terminal and encoder（8）Output terminal and probe socket（2）It is connected.
- 2. low frequency array eddy current testing device according to claim 1, it is characterised in that the bottom plate（1a）Radian be 2 π/3, detection coil（11）There are uniformly distributed 8, vortex collection signal transmssion line there are 8 one-to-one with detection coil.
- 3. low frequency array eddy current testing device according to claim 1, it is characterised in that be respectively provided with the housing with The digital knob that controller is connected（21）, power switch（22）, charging socket（23）, USB interface（25）, grounding receptacle（26）With RS-232 printer interfaces（27）.
- 4. low frequency array eddy current testing device according to claim 1, it is characterised in that the housing（1）Top is set There is handle（3）.
- 5. low frequency array eddy current testing device according to claim 1, it is characterised in that the guiding rubber tire（4）Have 4 It is a, be arranged on the both sides of Housing Base two-by-two respectively, be oriented to rubber tire bottom stretch out housing lower face, and in downwards, to Tilted setting.
- 6. low frequency array eddy current testing device according to claim 1, it is characterised in that the housing（1）On be provided with With probe socket（2）Connected freezes zeroing switches（6）.
- 7. low frequency array eddy current testing device according to claim 1, it is characterised in that the magnetic tank（10）Using iron Gan Oxygen is made, and each magnetic tank covers and its one-to-one detection coil.
- 8. low frequency array eddy current testing device according to claim 1, it is characterised in that total shielding braid net （131）With sub-thread shielding braid net（132）It is made of nylon mesh grid.
- A kind of 9. ferromagnetic steel pipe inner wall corrosion defects detection side using low frequency array eddy current testing device described in claim 1 Method, it is characterised in that comprise the following steps：A, abandoned tender standard is sentenced to detection and is demarcatedSensitivity comparison test tube is processed first, same batch heating surface pipe is taken, is splitted along tube center, successively in tube wall week To at interval of 20 ° of positions, 4 a diameter of Φ 6mm of equally spaced axially processing, the artificial defect that hole depth is 20% design wall thickness Blind hole, is scanned detection, with detection sensitivity to having a competition by low frequency array eddy current testing device to Sensitivity comparison test tube The depth value of the P-T scanning curve amplitude standardization defects of artificial defect on pipe, and sentence abandoned tender standard as detection, set the scanning to believe Number digital baseband input signal, depth and defect shared wall thickness percentage, the defects of amplitude is exceeded in checkout procedure, should Carry out sentencing useless processing；During Scanning Detction, two groups of guiding rubber tires are close to the surface of Sensitivity comparison test tube, promote probe to be detected manually, when The magnet exciting coil of alternating current is loaded with close to when contrasting test tube made of conductive magneto-conductive steel pipe, due to the effect of coil magnetic field, Vortex can be generated in conductive magneto-conductive steel pipe, size, phase and the liquid form of vortex are influenced by conductive material performance, and whirlpool The raw counter magnetic field of miscarriage makes the impedance of detection coil change again, and vortex is shown in after amplifier signal enhanced processing In the display for detecting host；The P-T scanning curves are vortex phase shift amount time history plot picture；B, defect locationTwo groups of guiding rubber tires are close to steel pipe to be measured（5）Surface, manually promote probe be detected, with less than 3~5 ms/min Clock Scanning speed uniform scanning is tested tube outer surface；Electric current is sent into by connecting line by controller after low-frequency oscillator is handled and visited Head excitation coil, magnetic flux caused by excitation coil covers 8 detection coils, and amplifies each inspection by 8 passage preamplifiers Test coil gathers signal, and is transmitted to EDDY CURRENT host through connecting line, when tested heating surface tube zero defect, then space scattering Leakage magnetic flux balance and symmetry, the output of each detection coil is zero, and when tested heating surface tube is defective, defect is to magnetic flux and vortex field Disturbance leakage magnetic flux asymmetric distribution is occurred, thus the detection coil in defect can produce unbalanced signal, and unbalanced signal is through low After noise amplifier amplification, then through balance filter filtering and automatic digital formula electronic equilibrium, Jiang Gexian is placed in reference " zero " electricity Flat, wave filter and self balancing time constant are set by controller, filter and balance after the defects of signal respectively enter shifting Phase device and gain adjustable amplifier carry out phase angle fixation and signal amplification, are sent into and control into digital signal through analog-to-digital conversion after amplification Device processed, and show over the display, realize the positioning of defective locations：1）Defect is circumferentially positionedInner wall defect detection is carried out to heating surface tubes in boilers by low frequency array eddy current probe, probe can cover tested 120 ° of tube wall Scope, the P-T scanning curves of each detection coil are independently presented and corresponding with coil array position, when probe is by defective Tube wall when, corresponding detection coil will cut the magnetic line of force drained to outside tube wall and induce a maximum voltage signal, should The impedance of coil can also change and be presented on P-T scanning curves, so that it is determined that the circumferential position of defect, and lacked to circumferential It is trapped into capable record；2）Defect axially positionIf being found in detection process, defect needs to store detection data, can select external trigger, that is, the arteries and veins for upper encoder of popping one's head in Signal triggering is rushed, P-T scanning curves are synchronous with probe scanning detection at this time, and scanning detects probe forward, and P-T scanning curves are synchronous Rolls forward is shown, is shown the distance that probe scanning detection is passed by screen at the same time, is needed to check when running into defect, probe is back Scanning detects, then erasing in real time retreats the equidistant P-T scanning curves distance passed by with probe on screen, so that it is determined that lacking Sunken axial location, and axial flaw is recorded；C, defect is checkedIt will locate surface the defects of positioning and remove totally, and coat couplant, with sonigauge repetition measurement, to confirm depth of defect, Tube surface geometry is irregular, butt weld, and pipe bent position, pipe end and internal stress may can all be brought tired to defect estimation Disturb, therefore, detection final result is subject to sonigauge and is checked；D, verified once with Sensitivity comparison test tube when 2 is small, if people's industrial injury is difficult to distinguish on Sensitivity comparison test tube, it Preceding detection is invalid.
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| CN109270464A (en) * | 2018-07-31 | 2019-01-25 | 华南理工大学 | Lead-acid accumulator Temperature of junction bar stress mornitoring method and apparatus based on ultrasound |
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| CN112730599A (en) * | 2020-12-27 | 2021-04-30 | 北京工业大学 | Buried pipeline damage harmonic magnetic field detection system based on FPGA and implementation method |
| CN114428112A (en) * | 2021-12-13 | 2022-05-03 | 中国石油化工股份有限公司 | Multi-channel near-field eddy current detection method for corrosion defects of inner wall of finned tube of air cooler |
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