KR102111366B1 - Probe and system for nondestructive testing of moisture separator and reheater tube - Google Patents

Abstract

The present invention relates to a probe and a system for nondestructive inspection of a heat transfer tube of a moisture separator and reheater of a ferromagnetic material having a curved tube unit and a heat transfer fin. An objective of the present invention is to distinguish the position and shape of a defect by simultaneously measuring a leakage flux of a defect in a circumferential direction and an eddy current of a defect in an axial direction. According to an embodiment of the present invention, the probe for nondestructive inspection of a heat transfer tube of a moisture separator and reheater comprises: a housing having an outer diameter smaller than the inner diameter of a heat transfer tube to be inspected; a magnet inserted into the housing; a differential magnetic sensor which encloses a portion of an outer wall of the housing corresponding to the position of the inserted magnet, and is arranged to be circumferentially parallel with an inner wall of the heat transfer tube when inserted into the heat transfer tube; and an excitation coil enclosing the differential magnetic sensor.

Description

Probe and system for nondestructive testing of moisture separator and reheater tube}

The present invention relates to a probe and a system for non-destructive inspection of a heat transfer tube of a moisture separation reheater, and more specifically, while minimizing distortion of an electromagnetic field by a heat transfer fin and a tube support plate, leakage flux of a circumferential defect and eddy current of an axial defect It relates to a probe and a system for non-destructive inspection of a moisture separation reheater tube that can measure and indicate simultaneously, determine the location of a defect based on this, and evaluate the depth.

A moisutre separator and reheater in a nuclear power plant refers to a facility that separates and reheats the moisture of the expanded steam that has passed through a high-pressure turbine and supplies it to a low-pressure turbine. Moisture separator reheater is one of the important facilities that affect the power output of the power plant, and the heat transfer pipe of the moisture separator reheater is a ferromagnetic material such as carbon steel or ferrite-based stainless steel having excellent high temperature strength under operating conditions such as high temperature and high pressure. It is made of.

The heat transfer tubes maintain a constant distance from each other by a carbon steel tube support plate. However, in the heat transfer process of the moisture separation reheater, the heat exchanger tube and the tube support plate are brought into contact by the flow of the heat exchange medium, and the heat pipe part under the tube support plate is very vulnerable to defect.

Such defects in the heat pipe may occur due to erosion, vibration wear, stress corrosion cracking, etc. during operation of the moisture separation reheater, and periodic non-destructive testing is required to evaluate the safety of the heat pipe for normal operation of the power plant. Do.

 There is a bobbin-type eddy current testing method as a method for inspecting the safety of a heat transfer tube, but in the case of a heat transfer tube composed of a ferromagnetic material such as a heat transfer tube of a moisture separation reheater, the penetration depth of the eddy current due to a skin effect Is limited and there is a limit in detecting defects.

To overcome this, the remote field eddy current test (RFECT), the leak magnetic flux test (MFLT), and the partially saturated eddy current test (PSECT) have been proposed. It is difficult to discriminate the defects on the heat-treated pipe, and in the case of the partial saturation eddy current inspection method, it is difficult to implement an inspection device because a strong external magnetic field must be input.

KR 1158411 B1

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a probe and a system for non-destructive inspection of a heat transfer tube tube of a moisture separator reheater having a complex structure in which a straight section and a curved section are integrated.

In addition, the present invention is a ferromagnetic material, the moisture separation to determine the location and shape of the defect by simultaneously measuring the leakage magnetic flux of the circumferential defect and the eddy current of the axial defect even when the heat pipe having the heating pin passes through the tube support plate. It is an object of the present invention to provide a probe and a system for non-destructive inspection of the reheater tube.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood from the following description.

Probe for non-destructive inspection of the moisture separation reheater heat pipe tube according to an embodiment of the present invention includes a housing having an outer diameter smaller than the inner diameter of the heat pipe to be inspected; A magnet inserted into the housing; A differential magnetic sensor that surrounds a part of the outer wall of the housing corresponding to the position of the inserted magnet, and is arranged in a circumferential direction parallel to the inner wall of the heat pipe when inserted inside the heat pipe; And an excitation coil surrounding the differential magnetic sensor.

The axial length of the magnet may be 3 times or more of a gap between the plurality of heat transfer fins protruding from the outer surface of the heat transfer tube.

The axial length of the probe may be smaller than the value of the following equation.

Here, L is the axial length of the probe, R is the radius of central curvature of the heat pipe, γ is the radius of the inner wall of the heat pipe, d is the diameter of the magnet, t is the thickness of the excitation coil, h is the height of the differential magnetic sensor, α is the margin Means

The differential magnetic sensors may be connected to each other by being spaced apart from each other at an interval corresponding to an integer multiple of the spacing between the plurality of heat transfer fins protruding from the outer surface of the heat pipe.

The width of the excitation coil may be an integer multiple of 3 times or more of a gap between a plurality of heat transfer fins protruding from the outer surface of the heat transfer pipe.

The probe may further include a pair of jigs fastened to both ends of the housing.

Non-destructive testing system for the moisture separation reheater heat pipe tube according to an embodiment of the present invention includes the probe; And it may include a signal processing circuit for branching the signal output from the probe and converting it to a digital signal.

The signal processing circuit includes: an amplifying circuit for amplifying a signal output from the differential magnetic sensor; A first branch circuit for branching the signal output from the amplifying circuit into a first signal and a second signal; A low-pass filter for extracting a DC component signal from the first signal and a high-pass filter for extracting an AC component signal from the second signal; A phase delay circuit for outputting a first square wave having the same phase as the AC current input to the excitation coil and a second square wave having a phase difference of 90 degrees from the AC current input to the excitation coil; A second branch circuit for branching the signal passing through the high-pass filter into a third signal and a fourth signal; A multiplication circuit for multiplying the third signal and the fourth signal by the first square wave and the second square wave, respectively; An integrating circuit for integrating each signal passing through the multiplication circuit and outputting a first analog signal and a second analog signal; And a digital conversion circuit that converts the first analog signal, the second analog signal, and the third analog signal that has passed through the low-pass filter into first digital signals, second digital signals, and third digital signals, respectively. have.

The amplification circuit may amplify a signal output from the differential magnetic sensor.

The first branch circuit may branch signals output from the amplification circuit into DC signals having the same size as each other, first AC signals, and second AC signals.

The non-destructive inspection system includes an AC power supply for applying an AC current to the excitation coil; And a sensor power supply for applying a DC current to the differential magnetic sensor.

The non-destructive inspection system stores the first digital signal, the second digital signal, and the third digital signal, and calculates the amplitude and phase difference of the AC component signal using the first digital signal and the second digital signal. Processing unit; And it may further include a graph generating unit for generating a graph using the data calculated from the central processing unit.

The probe and system for non-destructive inspection of the moisture separation reheater heat pipe tube according to an embodiment of the present invention has the advantage of being capable of non-destructive inspection of the moisture separation reheat tube heat pipe tube of a complex structure in which a straight section and a curved section are integrated.

In addition, the probe and system for non-destructive inspection of the moisture separation reheater heat pipes according to an embodiment of the present invention have the advantage that defects can be measured while minimizing the distortion of the electromagnetic field caused by the heat transfer fins even in the case of heat pipes having heat transfer fins. have.

In addition, the probe and system for the non-destructive inspection of the moisture separation reheater heat pipe tube according to an embodiment of the present invention has an advantage that the circumferential defect and the axial defect of the heat pipe can be detected by one probe.

In addition, the probe and system for non-destructive inspection of the heat exchanger tube of the moisture separation reheater according to an embodiment of the present invention has an advantage of quantitatively measuring the position, shape, and depth of the heat exchanger defect.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

의 분포를 나타내는 도면이다.
도 5는 본 발명의 일 실시예에 따른 습분분리재열기 전열관 튜브 비파괴검사 시스템을 간략히 도시한 블록도이다.
도 6은 본 발명의 일 실시예에 따른 신호처리회로를 간략히 도시한 블록도이다.
도 7은 본 발명의 다른 실시예에 따른 습분분리재열기 전열관 튜브 비파괴검사 시스템을 나타내는 이미지이다.
도 8은 본 발명의 일 실시예에 따른 습분분리재열기 전열관 튜브 비파괴검사 시스템의 그래프 생성부로부터 생성된, 결함에 따른 교류성분 신호의 실수 성분, 허수 성분, 진폭, 위상차를 나타내는 그래프이다.
도 9는 도 8에서 #7~#13의 결함위치에서 교류성분 신호의 실수 성분 및 허수 성분 값의 변화를 그래프 생성부가 리사주 선도(lissajous curve)로 도시한 결과를 나타내는 그래프이다.1 is a side view of a probe for non-destructive inspection of a tube for heat transfer of a moisture separation reheater according to an embodiment of the present invention, as viewed from the side.
FIG. 2 is a diagram briefly showing that a probe for non-destructive inspection of a moisture separation reheater heat pipe tube according to an embodiment of the present invention is inserted into the heat pipe.
FIG. 3 is a diagram illustrating that a probe for non-destructive inspection of a moisture separation reheater heat pipe according to an embodiment of the present invention applies an induced current in the circumferential direction of the heat pipe and a magnetic field in the axial direction of the heat pipe.
FIG. 4 shows that the heat transfer tube is magnetized using a probe for non-destructive inspection of the heat exchanger tube of the moisture separation reheater according to an embodiment of the present invention, and measured through a magnetic sensor.

It is a diagram showing the distribution of.
5 is a block diagram briefly showing a non-destructive inspection system for a moisture separation reheater heat pipe tube according to an embodiment of the present invention.
6 is a block diagram briefly showing a signal processing circuit according to an embodiment of the present invention.
7 is an image showing a non-destructive inspection system for the heat exchanger tube of the moisture separation reheater according to another embodiment of the present invention.
8 is a graph showing the real component, imaginary component, amplitude, and phase difference of an AC component signal according to a defect, generated from a graph generation unit of a moisture separation reheater heat pipe tube non-destructive inspection system according to an embodiment of the present invention.
FIG. 9 is a graph showing a result of a graph generation unit showing a change in real and imaginary component values of an AC component signal at a defect location of # 7 to # 13 in FIG. 8 as a lisajous curve.

Specific structural or functional descriptions with respect to the embodiments of the present invention disclosed in the present specification or the application are exemplified for the purpose of illustrating the embodiments according to the present invention, and the embodiments according to the present invention may be implemented in various forms. And may not be construed as limited to the embodiments described in this specification or application.

Since the embodiment according to the present invention can be modified in various ways and have various forms, specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiment according to the concept of the present invention to a specific disclosure form, and it should be understood to include all modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

In the present specification, terms such as first and / or second are used only to distinguish one component from another component. That is, it is not intended to limit the components by the terms.

Elements, features, and steps referred to in the phrase 'include' in this specification mean that the elements, features, and steps exist, and are intended to exclude one or more other elements, features, steps, and the like. This is not.

In this specification, unless otherwise specified in the singular form, the plural form is included. That is, the components and the like referred to herein may mean the presence or addition of one or more other components.

Unless defined otherwise, all terms used in this specification, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains (ordinary skilled person). to be.

In other words, terms such as those defined in a commonly used dictionary should be interpreted as meanings consistent with meanings in the context of related technologies, and are interpreted as ideal or excessively formal meanings unless explicitly defined herein. Does not work.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings.

1 is a side view of a probe for non-destructive inspection of a moisture separation reheater heat pipe according to an embodiment of the present invention, and FIG. 2 is a non-destruction of a moisture separation reheater heat pipe tube according to an embodiment of the present invention It is a diagram briefly showing that a probe for inspection is inserted inside a heat transfer tube.

1 and 2, the probe 200 for non-destructive inspection of the moisture separation reheater tube heat pipe according to an embodiment of the present invention includes a housing 210, a magnet 220, a differential magnetic sensor 230, and an excitation coil (excitation coil) 240 and jig 250 may be included. In addition, the heat transfer pipe 10 may include a plurality of heat transfer fins (11) protruding from the outer surface of the heat transfer pipe (10).

The heat exchanger tube 10 may include a plurality of heat exchanger pins 11 protruding from the outer wall of the heat exchanger tube 10. The heat exchanger pin 11 may be located on the outer wall of the heat exchanger tube 10 to increase the heat transfer capacity of the heat exchange medium. In order to increase the cross-sectional area with the medium, the heat transfer fin 11 can be manufactured by spirally cutting the outer wall of the heat transfer tube 10 or performing plastic deformation. When the heat pipe 10 is cut and processed, the thickness of the heat-exchanging fins 11 is different from each other, and in the case of the heat-generating fins produced by plastic deformation, the density of the materials is different from the acid and the bones.

The housing 210 serves as a body of the probe 200, and a probe 200 capable of magnetizing the heat transfer tube 10 such as a magnet 220 and a differential magnetic sensor 230 inside the housing 210 and measuring magnetic flux density ) Core components can be inserted. The housing 210 is composed of a cylindrical shape of a pipe having an outer diameter smaller than the inner diameter of the heat transfer pipe 10 so as to enter the heat pipe 10 to be inspected, and is preferably made of a non-metal or non-magnetic material so as not to be affected by the magnetic field. Do.

The magnet 220 is located inside the probe 200 to magnetize the heat transfer tube 10 in the axial direction. The magnet 200 is preferably inserted into the housing 210 and configured in a cylindrical shape to form a uniform magnetic field.

FIG. 3 is a diagram illustrating that a probe for non-destructive inspection of a moisture separation reheater heat pipe according to an embodiment of the present invention applies an induced current in the circumferential direction of the heat pipe and a magnetic field in the axial direction of the heat pipe.

Referring to FIG. 3, it can be confirmed that the magnet 220 applies a magnetic field in the axial direction (z-direction) of the heat transfer tube 10. The induced current is induced in the circumferential direction (Φ-direction) of the heat exchanger tube 10 because an AC current is applied to the excitation coil 240, which will be described later.

When the magnet 220 magnetizes the heat transfer tube 10 in the axial direction, a circumferential (Φ-direction) defect and a change in the magnetic flux density distribution of the DC component from the heat transfer pin 11 occur, and the differential magnetic sensor 230 detects this You can output a signal. The magnetic field by the magnet 220 is focused on the mountains and valleys of the heat transfer fin 11. Here, the heat transfer pipe 10 serves to block the electromagnetic field, so that the magnetic field does not reach the tube support plate (TSP) supporting the heat transfer pipe 10.

In one embodiment, it is preferable that the axial length of the magnet 220 is equal to or greater than three times the spacing between the heat transfer fins 11. When the heat exchanger tube 10 is magnetized, an N-pole and an S-pole are generated at an intersection due to an edge effect in the bone or acid of the heat-transfer fin 11. In order to reduce the deviation of the generated stimulus, it is preferable that the axial length of the magnet 220 is more than three times the interval between the heat transfer fins 11.

The differential magnetic sensor 230 surrounds a portion of the outer wall of the housing 210 corresponding to the position of the inserted magnet 220, and when inserted inside the heat transfer tube 10, the inner wall of the heat transfer tube 10 in the circumferential direction And parallel. In the differential magnetic sensor 230, it is preferable that magnetic sensors spaced apart from each other are connected in a differential manner.

In one embodiment, the differential magnetic sensors 230 may be connected to each other by being spaced apart from each other at an interval corresponding to an integer multiple of the interval between the heat transfer fins 11. Although the magnetic fields of different strengths are generated in the mountains and valleys of the heat transfer fins 11, the distortion of the electromagnetic field is almost the same between the mountains and valleys of the heat transfer fins 11 or the valleys and valleys. Accordingly, when a pair of magnetic sensors 230 are spaced apart from each other by a distance corresponding to an integer multiple of the interval between the heat transfer fins 11, the intensity of the magnetic field measured at the second sensor is measured from the intensity of the magnetic field measured at the first sensor. If subtracted, the bias magnetic flux density, that is, the strength of the magnetic field, coming from the acid and the valley of the heat transfer fin 11 may be canceled. In addition, in some regions of the heat transfer pipe 10, when the heat transfer fins 11 are lost or when a defect occurs, the output of the magnetic sensor 230 can be maximized, so that the magnetic sensor 230 is differentially connected. It is preferred.

)이 최소화되고, 결함이 있을 경우,

이 최대화되는 바, 차동형 자기센서(230)는 반지름 방향(도 3의 r-방향)의 자기 감도를 가지는 것이 바람직하다.In addition, since the magnet 220 applies a magnetic field in the axial direction (z-direction), when there is no defect in the heat transfer tube 10, the radial component of the magnetic flux density (r-direction,

) Is minimized, and if there is a defect,

As it is maximized, the differential magnetic sensor 230 preferably has a magnetic sensitivity in a radial direction (r-direction in FIG. 3).

)가 최대가 된다. 따라서, 이 경우 차동형 자기센서(230)에 의해 출력되는 직류성분 신호(

) 또한 최대가 될 것이다. When the defect direction is the circumferential direction (Φ-direction in FIG. 3), the magnetic flux density of the DC component generated by the magnet 220 (

) Becomes the maximum. Therefore, in this case, the DC component signal output by the differential magnetic sensor 230 (

) Will also be the maximum.

The excitation coil 240 surrounds the differential magnetic sensor 230, and an AC current is applied to apply an induced current in the circumferential direction of the heat transfer tube 10.

In one embodiment, it is preferable to make the width of the excitation coil 240 more than three times the spacing between the heat transfer fins 11. An alternating magnetic field in the axial direction is generated when the magnetic fields of the N pole and the S pole cross the bones or mountains of the heat transfer fin 11. In order to reduce the deviation of the stimulus generated at this time, it is preferable that the width of the excitation coil 240 is at least three times the interval between the heat transfer fins 11.

)가 최대가 된다. 이로 인해 차동형 자기센서(230)에 의해 출력되는 교류성분 신호(

) 또한 최대가 될 것이다.On the other hand, the induced current in the circumferential direction by the excitation coil 240 is distorted to the maximum when the direction of the defect is in the axial direction (z-direction), and the distortion of the induced current is alternating magnetic flux density in the radial direction (r-direction). Causes a change. Therefore, when the defect direction is axial, the time-varying magnetic flux density of the AC component (

) Becomes the maximum. Due to this, the AC component signal output by the differential magnetic sensor 230 (

) Will also be the maximum.

)와 교류성분의 시변자속밀도(

)가 중첩된 신호가 차동형 자기센서(230)에 의하여 출력될 수 있다. When a defect is present in a portion of the heat transfer tube 10 of the portion overlapping the magnet 220 and the excitation coil 240, the leakage magnetic flux density of the DC component regardless of the direction of the defect (

) And the time-varying magnetic flux density of the AC component (

) Overlapped signal may be output by the differential magnetic sensor 230.

)가 최대가 될 것이며, 축방향의 결함의 경우에는 교류성분의 시변자속밀도 변화에 따른 출력 신호(

)가 최대가 될 것이다. 원주방향 및 축방향 결함이 중첩된 결함의 경우에는 출력 신호

,

가 중첩된 신호가 출력되는 바, 이를 분석하여 결함의 형상을 측정할 수 있다.The distribution of the leakage magnetic flux density of the DC component and the time-varying magnetic flux density of the AC component varies depending on the shape of the defect, and the shape and direction of the defect can be measured by measuring this through the differential magnetic sensor 230. For example, in the case of a defect in the circumferential direction, an output signal according to a change in the leakage magnetic flux density of the DC component (

) Will be the maximum, and in the case of an axial defect, the output signal according to the change in the time-varying flux density of the AC component (

) Will be the maximum. Output signal in case of defects with overlapping circumferential and axial defects

,

Since the superimposed signal is output, the shape of the defect can be measured by analyzing it.

의 분포를 나타내는 도면이다. 여기서, 그래프의 종축인 좌측 사선은 각도, 즉, 원주방향으로 배열된 차동형 자기센서(230)의 위치를 나타내고, 그래프의 횡축인 우측 사선은 거리, 즉, 전열관(10)에서의 위치를 나타낸다. 또한, FBH는 평저공 결함(flat bottomed hole)을 의미하고, OD 및 ID는 각각 외측 결함 및 내측 결함을 의미하며, 그래프의 높낮이는 각 좌표에서 측정된

값을 나타낸다.FIG. 4 is a magnetization of the heat pipe using a probe for non-destructive inspection of the heat pipe of the moisture separation reheater according to an embodiment of the present invention, and measured through a differential magnetic sensor.

It is a diagram showing the distribution of. Here, the left diagonal line, which is the vertical axis of the graph, represents an angle, that is, the position of the differential magnetic sensor 230 arranged in the circumferential direction, and the right diagonal line, which is the horizontal axis of the graph, represents the distance, that is, the position in the heat transfer tube 10. In addition, FBH means flat bottomed hole, OD and ID mean outer defect and inner defect, respectively, and the height of the graph is measured at each coordinate.

Value.

의 분포가 다르게 측정되는 것을 확인할 수 있다. 이러한 그래프는 최종적으로 그래프 생성부에 의해 생성되는데 이에 대한 내용은 후술하기로 한다.4, according to the location and depth of the defect

It can be seen that the distribution of is measured differently. These graphs are finally generated by the graph generator, which will be described later.

In addition, it is preferable that the axial length of the probe 200 for non-destructive inspection of the moisture separation reheater heat pipe tube is smaller than Equation 1 below.

Here, L is the axial length of the probe, R is the radius of central curvature of the heat pipe, γ is the radius of the inner wall of the heat pipe, d is the diameter of the magnet, t is the thickness of the excitation coil, h is the height of the differential magnetic sensor, α is the margin (Gap between the outer diameter of the probe and the inner diameter of the heat pipe; lift-off).

The smaller the margin, the greater the output of the differential magnetic sensor 230, and the larger the margin, the greater the wear of the differential magnetic sensor 230.

When the axial length L of the probe 200 is smaller than Equation 1, defects can be measured even inside the heat transfer tube 10 formed of a curve, so that the condition of Equation 1 is satisfied in order to measure defects in a heat transfer tube having a complicated structure. It is preferred.

In addition, since the distance between the acid of the heat transfer pin 11 and the mountain is generally about 1 mm, even if the differential magnetic sensor 230 is connected to a position spaced apart by a distance of 4 to 5 mountains, the sensor width is about 5 mm. The length is shorter than that of the prior art, and inspection of the curved portion is possible.

Jig 250 may be composed of a pair, fastened to both ends of the housing 210, the magnet 220, the differential magnetic sensor 230 and the excitation coil 240 parallel to the inner wall from the center of the heat pipe (10) It can play a fixed role of positioning. According to the Biot-Savart law, the magnitude of a magnetic field due to electric current is inversely proportional to the square of the distance. In addition, the magnetization by a magnet may also be applied to the Bio-Savar law. Accordingly, when the magnet 220 and the excitation coil 240 are not deviated from or parallel to the center of the heat exchanger tube 10, the size of the magnetic field reaching the heat exchanger tube 10 may be uneven. Magnetization and excitation coil of heat transfer tube 10 by magnet 220 by fixing jig 250 at both ends of housing 210 to fix magnet 220, differential magnetic sensor 230, and excitation coil 240 It is possible to make the magnetic field by the current flowing in 240) uniform.

5 is a block diagram briefly showing a non-destructive inspection system for a moisture separation reheater heat pipe tube according to an embodiment of the present invention.

Referring to Figure 5, the moisture separation reheater heat pipe tube non-destructive inspection system 20 according to an embodiment of the present invention is a probe 200 and signal processing circuit 300 for the moisture separation reheater heat pipe tube non-destructive inspection It can contain.

The signal processing circuit 300 serves to branch the signal output from the differential magnetic sensor 230 of the probe 200 and convert it into a digital signal.

6 is a block diagram briefly showing a signal processing circuit according to an embodiment of the present invention.

Referring to FIG. 6, in one embodiment, the signal processing circuit 300 includes an amplifying circuit 310, a first branch circuit 320, a low-pass filter 330, a high-pass filter 340, and a phase It may include a delay circuit 350, a second branch circuit 360, a multiplication circuit 370, an integration circuit 380 and a digital conversion circuit (390).

The amplifying circuit 310 receives a signal output from the differential magnetic sensor 230 and amplifies the signal.

In one embodiment, the amplifying circuit 310 is preferably AC amplifying the output signal of the differential magnetic sensor 230. The heat pipe 10 has a narrow and long shape, and an elongated signal line is required to transmit an output signal, but when the signal line is elongated, the resistance increases, causing signal attenuation. Therefore, it is preferable to amplify the output signal by alternating current to compensate for the attenuation of the signal and measure the output signal in which the DC component and the AC component overlap.

,

신호를 포함하고 있는 증폭된 출력신호를 균등하게 제1 신호 및 제2 신호로 분기할 수 있다. 제1 분기회로(320)로부터 분기된 신호가 저대역 통과필터(330) 및 고대역 통과필터(340)를 통과함으로써 증폭된 출력신호가 직류성분 신호 및 교류성분 신호로 분기될 수 있다. The first branch circuit 320 may branch the output signal amplified from the amplification circuit 310 for the purpose of extracting DC components and AC component signals. The first branch circuit 320

,

The amplified output signal including the signal may be equally branched into the first signal and the second signal. The signal branched from the first branch circuit 320 passes through the low-pass filter 330 and the high-pass filter 340 so that the amplified output signal can be branched into a DC component signal and an AC component signal.

)을 추출하기 위한 신호가 되고, 2/3은 교류성분(

)을 추출하기 위한 신호가 되도록 분기하는 것이 바람직하다. In one embodiment, the first branch circuit 320 may branch the amplified output signals into DC signals having the same size as each other, first AC signals, and second AC signals. Subsequently, when calculating the phase difference of the AC component signals, the amplitudes of the branched AC component signals should be the same as each other. At this time, when the first branch circuit 320 branches the signal of the same size, there is an advantage that the phase difference operation can be performed without a separate amplifier circuit. Therefore, 1/3 of the signal branched from the first branch circuit 320 is a DC component (

), And 2/3 is the AC component (

It is desirable to branch to become a signal for extracting).

)를 추출할 수 있다. 따라서, 저대역 통과필터(330)를 통과한 신호는 원주방향의 결함을 검출하는 데 활용될 수 있다.The low-pass filter 330 receives one branched signal from the first branch circuit 320 and the DC component signal according to the change in the leakage magnetic flux density of the DC component (

) Can be extracted. Therefore, the signal that has passed through the low-pass filter 330 can be used to detect defects in the circumferential direction.

)를 추출할 수 있다. 따라서, 고대역 통과필터(340)를 통과한 신호는 축방향의 결함을 검출하는 데 활용될 수 있다.The high-pass filter 340 receives another signal branched from the first branch circuit 320, and the AC component signal according to the change in the time-varying flux density of the AC component (

) Can be extracted. Therefore, the signal that has passed through the high-pass filter 340 can be utilized to detect axial defects.

The phase delay circuit 350 may output a first square wave having a phase equal to an AC current input to the excitation coil 240 and a second square wave having a phase difference of 90 degrees from the AC current. The output first and second square waves are multiplied by the AC component signals branched from the second branch circuit 360, so that the AC component signals can be divided into real components and imaginary components.

)를 크기가 같은 두 개의 신호인 제3 신호 및 제4 신호로 분기할 수 있다. 제2 분기회로(360)에서 분기된 교류성분 신호인 제3 신호 및 제4 신호는 위상지연회로(350)에서 출력된 제1 사각파 및 제2 사각파와 각각 곱해짐으로써 교류성분 신호가 실수 성분 및 허수 성분으로 분기될 수 있다. The second branch circuit 360 is an AC component signal extracted through the high-pass filter 340 (

) May be split into two signals having the same size, the third signal and the fourth signal. The third and fourth signals, which are AC component signals branched from the second branch circuit 360, are multiplied by the first square wave and the second square wave output from the phase delay circuit 350, respectively, so that the AC component signal is a real component. And imaginary components.

The multiplication circuit 370 may perform a function of multiplying the third and fourth signals, which are signals branched from the second branch circuit 360, with the first square wave and the second square wave output from the phase delay circuit 350. have. That is, in one embodiment, the third signal may be multiplied by the first square wave and the fourth signal by the second square wave. As the signal passes through the multiplication circuit 370, the AC component signal can be divided into real components and imaginary components.

와 허수 성분인

로 분기할 수 있다.Here, the AC component signal may be branched into a signal having the same phase as the AC current input to the excitation coil 240 and a signal having a phase difference of 90 degrees from the AC current input to the excitation coil 240. That is, the AC component signal is a real component of the AC component signal.

And imaginary ingredients

You can branch to

The real component and the imaginary component of the branched AC component signal can be expressed by Equation 2 below.

Here, Z is the amplitude, Ψ is the phase difference, and the amplitude and the phase difference can be expressed as Equation 3 below.

Here, Φ is the angle (the position of the magnetic sensors arranged in the circumferential direction), and z is the distance (position) from the heat pipe.

,

의 크기가 동일한 것을 전제로 하므로 분기된 실수 성분 및 허수 성분 신호는 동일한 크기를 갖는 것이 바람직하다.As described above, the amplitude and phase difference of the AC component signal can be calculated based on the signal branched into the real component and the imaginary component. Where the phase difference is

,

Since it is assumed that the magnitudes of are the same, it is preferable that the branched real component and imaginary component signals have the same magnitude.

, 허수 성분

을 각각 직류 신호로 변환한 제1 아날로그신호 및 제2 아날로그신호를 출력할 수 있다.The integrating circuit 380 integrates the signal output from the multiplication circuit 370 and finally serves to output a DC signal. That is, it serves to convert the AC component signal to a DC component signal. The integration circuit 380 is a real component of the AC component signal output from the multiplication circuit 370

, Imaginary ingredients

Each of the first analog signal and the second analog signal converted to DC signals may be output.

및 제2 아날로그신호

와 저대역 통과필터(330)를 통과한 제3 아날로그신호(

)를 각각 제1 디지털신호, 제2 디지털신호 및 제3 디지털신호로 변환하는 역할을 수행한다. 아날로그신호를 디지털신호로 변환하여 중앙처리부로 디지털신호를 입력하고 입력된 신호를 바탕으로 중앙처리부 및 그래프 생성부가 연산 및 그래프 생성 과정을 수행토록 하기 위함이다.The digital conversion circuit 390 is the first analog signal output from the integration circuit 380

And second analog signal

And a third analog signal passing through the low-pass filter 330 (

) To convert the first digital signal, the second digital signal, and the third digital signal, respectively. This is to convert the analog signal to a digital signal, input the digital signal to the central processing unit, and perform the calculation and graph generation process by the central processing unit and the graph generation unit based on the input signal.

In one embodiment, the moisture separation reheater heat pipe tube non-destructive inspection system 20 may further include a sensor power source (not shown) and an AC power source (not shown).

The sensor power is connected to the differential magnetic sensor 230 to apply a direct current to the differential magnetic sensor 230. That is, the current flows stably by the sensor power, and a voltage difference or impedance change may be induced in the differential magnetic sensor 230 due to a change in magnetic flux density.

The AC power is connected to the excitation coil 240 to apply an AC current to the excitation coil 240. That is, the AC power outputs a sinusoidal wave to apply an AC current to the excitation coil 240, and an induced current may be applied in the circumferential direction to the heat transfer tube 10 by the AC current flowing through the excitation coil 240.

In one embodiment, the moisture separation reheater heat pipe tube non-destructive inspection system 20 may further include a central processing unit (not shown) and a graph generation unit (not shown).

In one embodiment, the central processing unit and the graph generation unit may be included in the electronic device. For example, the electronic device may be a personal computer (PC), a laptop, a personal digital assistant (PDA), or a mobile phone, but the present invention is not limited or limited thereto.

7 is an image showing a non-destructive inspection system for the heat exchanger tube of the moisture separation reheater according to another embodiment of the present invention.

Referring to FIG. 7, it is confirmed that the moisture separation reheater heat pipe tube non-destructive testing system 20 includes a probe 200 for non-destructive testing of the moisture separation heat pipe inserted inside the heat pipe and a PC including a central processing unit and a graph generating unit Can be. That is, the output signal is obtained through the differential magnetic sensor 230 of the probe 200 inserted inside the heat transfer tube 10, the output signal is converted into a digital signal through the signal processing circuit 300, and the converted digital signal is converted. Based on this, the central processing unit and the graph generation unit perform calculations and graphs.

The central processing unit may receive first digital signals, second digital signals, and third digital signals converted from the digital conversion circuit 390. After storing the received digital signals, the amplitude and phase difference of the AC component signal may be calculated using the first digital signal and the second digital signal corresponding to the AC component signal.

That is, the central processing unit can calculate the amplitude and phase difference of the AC component signal using the digital signals input through Equations 2 and 3 above.

The graph generation unit may generate and display a graph of the DC component signal and the amplitude and phase difference of the AC component signal by using the data calculated from the central processing unit. The user can check the location, size, depth, shape, etc. of the defects in the heat pipe 10 through the generated graph.

Figure 8 is a graph showing the real component, imaginary component, amplitude, phase difference of the AC component signal according to the defect, generated from the graph generator of the moisture separation reheater heat pipe non-destructive inspection system according to an embodiment of the present invention.

는 교류성분 신호의 실수 성분,

는 허수 성분을 나타낸다. 이는 진폭(Z)과 위상차(phi)를 계산하기 위하여 측정하는 값이다. 연산된 진폭의 크기가 클수록 결함의 크기가 크다는 뜻이고, 위상차는 결함의 위치와 깊이에 따라 다르게 나타난다.Referring to Figure 8,

Is the real component of the AC component signal,

Represents an imaginary component. This is a value measured to calculate the amplitude (Z) and phase difference (phi). The larger the amplitude of the calculated amplitude, the greater the size of the defect, and the phase difference appears differently depending on the location and depth of the defect.

In each graph, the vertical axis represents the angle (the position of the magnetic sensors arranged in the circumferential direction), and the horizontal axis represents the distance of the heat pipe, that is, the position. The amplitude and phase difference are calculated from real and imaginary components of the AC component signal. That is, the graph generator may display real components, imaginary components, and amplitudes and phase differences calculated from the AC component signals in graph coordinates as differences in height or color of the graph. Referring to FIG. 8, it can be confirmed that the amplitude and phase difference of the AC component signal detected from the defect of the heat transfer tube 10 are calculated and illustrated in a graph, from which the size of the defect, etc. can be grasped. In addition, although there is a tube support plate (TSP) between defects # 11 and # 12, it can be confirmed that detection was completed for all defects without being affected by this.

FIG. 9 is a graph showing a result of a graph generation unit showing a change in real and imaginary component values of an AC component signal at a defect location of # 7 to # 13 in FIG. 8 as a lisajous curve.

Referring to FIG. 9, it can be seen that the inner defect ID is counterclockwise and the outer defect OD is rotated clockwise based on the Lissajous line in the flat bottom hole (FBH) 100% defect. That is, the location of the defect can be confirmed through a Lissajous diagram showing changes in real and imaginary component values of the AC component signal.

In one embodiment, the moisture separation reheater heat pipe tube non-destructive testing system 20 may further include a multi-channel power source (not shown). Multi-channel power supply is amplification circuit 310, low-pass filter 330, high-pass filter 340, multiplication circuit 370, integration circuit 380, digital conversion circuit 390, central processing unit and graph generation It can serve to supply power to the wealth.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present invention.

10: heat transfer tube 11: heat transfer fins
20: non-destructive inspection system 200: probe
210: housing 220: magnet
230: differential magnetic sensor 240: excitation coil
250: fixture 300: signal processing circuit
310: amplification circuit 320: first branch circuit
330: low-pass filter 340: high-pass filter
350: phase delay circuit 360: second branch circuit
370: multiplication circuit 380: integration circuit
390: digital conversion circuit

Claims (12)

A housing having a smaller outer diameter than the inner diameter of the heat transfer tube, including a plurality of heat transfer fins;
A magnet inserted into the housing;
Surrounds a part of the outer wall of the housing at a position corresponding to the position of the inserted magnet, and is spaced apart at predetermined intervals according to the interval between the heat exchange pins so that at least a part of the magnetic field by the heat exchange pins is offset and arranged differentially A first magnetic sensor and a second magnetic sensor, and when inserted inside the heat pipe, the first magnetic sensor and the second magnetic sensor are arranged in a circumferential direction to be parallel to the inner wall of the heat pipe. sensor); And
Comprising an excitation coil surrounding the differential magnetic sensor,
Probe for non-destructive testing of heat transfer tube of moisture separator reheater. According to claim 1,
The axial length of the magnet,
More than 3 times the spacing between the plurality of heat transfer fins protruding from the outer surface of the heat transfer tube,
Probe for non-destructive testing of heat transfer tube of moisture separator reheater. According to claim 1,
The axial length of the probe is smaller than the value of the following equation,
Probe for non-destructive testing of heat transfer tube of moisture separator reheater.

Here, L is the axial length of the probe, R is the central radius of curvature of the heat pipe, γ is the radius of the inner wall of the heat pipe, d is the diameter of the magnet, t is the thickness of the excitation coil, h is the height of the differential magnetic sensor, α is the margin Means delete According to claim 1,
The width of the excitation coil is an integer multiple of 3 times or more of the spacing between the plurality of heat transfer fins protruding from the outer surface of the heat transfer pipe,
Probe for non-destructive testing of heat transfer tube of moisture separator reheater. According to claim 1,
The probe,
Further comprising a pair of jigs fastened to both ends of the housing,
Probe for non-destructive testing of heat transfer tube of moisture separator reheater. The probe of claim 1; And
The signal output from the probe is branched, and a DC component signal of the branched signal, an AC component signal of the branched signal, an amplitude component signal and a phase component signal are identified, and the DC component signal, the amplitude component signal, and And a signal processing circuit for outputting together the DC component signal, the amplitude component signal, and the digital signals corresponding to each of the phase component signals by converting the phase component signals.
Non-destructive inspection system for heat transfer tube of moisture separator reheater. The method of claim 7,
The signal processing circuit,
An amplifying circuit for amplifying the signal output from the differential magnetic sensor;
A first branch circuit for branching the signal output from the amplifying circuit into a first signal and a second signal;
A low-pass filter for extracting a DC component signal from the first signal and a high-pass filter for extracting an AC component signal from the second signal;
A phase delay circuit for outputting a first square wave having the same phase as the AC current input to the excitation coil and a second square wave having a phase difference of 90 degrees from the AC current input to the excitation coil;
A second branch circuit for branching the signal passing through the high-pass filter into a third signal and a fourth signal;
A multiplication circuit for multiplying the third signal and the fourth signal by the first square wave and the second square wave, respectively;
An integrating circuit for integrating each signal passing through the multiplication circuit and outputting a first analog signal and a second analog signal; And
And a digital conversion circuit that converts the first analog signal, the second analog signal, and the third analog signal that has passed through the low-pass filter into first digital signals, second digital signals, and third digital signals, respectively.
Non-destructive inspection system for heat transfer tube of moisture separator reheater. The method of claim 8,
The amplification circuit,
AC amplifying the signal output from the differential magnetic sensor,
Non-destructive inspection system for heat transfer tube of moisture separator reheater. The method of claim 8,
The first branch circuit,
Branching the signal output from the amplification circuit to a DC signal having the same size as each other, a first AC signal and a second AC signal,
Non-destructive inspection system for heat transfer tube of moisture separator reheater. The method of claim 7,
The non-destructive inspection system,
An AC power supply for applying an AC current to the excitation coil; And
Further comprising a sensor power for applying a direct current to the differential magnetic sensor,
Non-destructive inspection system for heat transfer tube of moisture separator reheater. The method of claim 8,
The non-destructive inspection system,
A central processing unit for storing the first digital signal, the second digital signal and the third digital signal, and calculating the amplitude and phase difference of the AC component signal using the first digital signal and the second digital signal; And
Further comprising a graph generating unit for generating a graph using the data calculated from the central processing unit,
Non-destructive inspection system for heat transfer tube of moisture separator reheater.

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