JPS6254113A - Thickness measuring method for scale in pipe - Google Patents
Thickness measuring method for scale in pipeInfo
- Publication number
- JPS6254113A JPS6254113A JP19408285A JP19408285A JPS6254113A JP S6254113 A JPS6254113 A JP S6254113A JP 19408285 A JP19408285 A JP 19408285A JP 19408285 A JP19408285 A JP 19408285A JP S6254113 A JPS6254113 A JP S6254113A
- Authority
- JP
- Japan
- Prior art keywords
- pipe
- scale
- thickness
- ultrasonic
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)
Abstract
Description
この発明は、流体の通流する管内部に発生したスケール
の厚さを超音波を利用して測定する方法に関する。The present invention relates to a method of measuring the thickness of scale generated inside a pipe through which fluid flows using ultrasonic waves.
管内部に生じたスケール厚さの測定方法として放射線源
による放射線透過写真撮影法、放射線がスケールにより
吸収、減衰される性質を利用してその減衰割合から測定
する放射線式測定法、スケールにより管内の透磁率が変
化する性質を利用した電磁式測定法、スケールによって
管内の熱伝導性が変化する性質を利用してその温度勾配
からスケール厚さを求める測定法等が従来より知られて
いる。しかしてこれら従来技術による測定方法はいずれ
も測定の簡便さに欠け、また通用対象が限定される等の
問題点がある。
また別な測定方式としてスケールによる超音波の反射の
性質を利用し、超音波の反射時間から管内スケール厚さ
を測定する超音波反射式測定法も知られているが、この
超音波反射式測定法においては、スケールと流体との境
界面では流体とほぼ等しい音響インピーダンスを持つの
で、管内スケール厚さに相当する前述の境界面からの反
射波が得られにクク、また得られた反射波が管内に付着
しているスケール厚さ方向での途中からの反射波である
可能性が大きいこと、管内多重反射の影響も大きいこと
など測定原理上の難点があり精度の高い測定結果が得ら
れない。The thickness of the scale formed inside the pipe can be measured using radiographic photography using a radiation source, radiation measurement method that uses the property that radiation is absorbed and attenuated by the scale, and measures the attenuation rate. Conventionally known methods include an electromagnetic measurement method that utilizes the property that magnetic permeability changes, and a measurement method that uses the property that thermal conductivity within a pipe changes depending on the scale and determines the scale thickness from the temperature gradient. However, all of these conventional measuring methods lack the simplicity of measurement and have problems such as limited applicability. Another measurement method is the ultrasonic reflection measurement method, which uses the properties of ultrasonic waves reflected by the scale to measure the thickness of the scale in the pipe from the reflection time of the ultrasonic waves. In the method, since the interface between the scale and the fluid has almost the same acoustic impedance as the fluid, it is difficult to obtain a reflected wave from the aforementioned interface corresponding to the thickness of the scale in the pipe, and the obtained reflected wave is It is difficult to obtain highly accurate measurement results due to difficulties in the measurement principle, such as the possibility that the waves are reflected from halfway through the thickness of the scale attached to the pipe, and the influence of multiple reflections within the pipe. .
この発明は上記の点にかんがみなされたものであり、前
記した従来における各種測定法の難点を解消して測定の
簡便さ、適用対象の制限等の9面での改善を図り、超音
波の減衰を利用して管の外方から節単に管内スケール厚
さを精度よく測定できるようにした測定方法を提供する
ことを目的とする。This invention has been made in consideration of the above points, and it solves the difficulties of the various conventional measurement methods mentioned above, improves it in nine aspects such as ease of measurement and restriction of applicable objects, and improves the attenuation of ultrasonic waves. It is an object of the present invention to provide a measurement method that enables accurate measurement of scale thickness inside a pipe from the outside of the pipe.
上記目的はこの発明により、管を挟んでその両側に管の
外壁より所定の間隙を隔てて超音波発信子と受信子とを
対向配置するとともに、該間隙を管内通流の流体と同種
の音響接合液体で満たし、この状態で発信子より受信子
へ向けて流体中に超音波を伝搬してその発信音圧と受信
音圧から超音波の減衰割合を検出し、該検出値とあらか
じめ既知のスケール厚さについて求めた超音波減衰率の
較正値とから演算により管内に付着しているスケール厚
さを求めるようにしたものである。
すなわち、超音波発信子から受信子へ向け、管との音響
カップリングを一定に保ために前記間隙を満たした音響
接合液および管壁を通して管内の流体中に発射された超
音波は、管内のスケールおよび流体中を通過して受信子
に受信される。この場合に流体中の超音波の減衰割合は
、伝搬距離と周波数の数乗に比例する。したがって流体
中に発射した超音波の周波数と超音波伝搬経路の距離と
から超音波の減衰割合を墳出し、この検出値と別途同じ
測定条件で既知のスケール厚さに付いて求めた超音波減
衰率の較正値とで演算を行うことにより、被測定の管内
に付着したスケールの厚さを測定することができる。The above object is achieved by the present invention, in which an ultrasonic transmitter and a receiver are arranged facing each other with a predetermined gap from the outer wall of the tube on both sides of the tube, and the gap is filled with the same type of acoustic wave as the fluid flowing through the tube. It is filled with a bonding liquid, and in this state, the ultrasonic wave is propagated through the fluid from the transmitter to the receiver, and the attenuation rate of the ultrasonic wave is detected from the emitted sound pressure and the received sound pressure, and the detected value and the previously known The thickness of the scale attached to the inside of the pipe is determined by calculation from the calibration value of the ultrasonic attenuation factor determined for the scale thickness. That is, the ultrasonic waves are emitted from the ultrasonic transmitter to the receiver into the fluid in the tube through the acoustic bonding liquid that filled the gap and the tube wall to maintain constant acoustic coupling with the tube. It passes through the scale and fluid and is received by the receiver. In this case, the attenuation rate of ultrasonic waves in the fluid is proportional to the propagation distance and the frequency raised to the power of a number. Therefore, the attenuation rate of the ultrasonic wave is determined from the frequency of the ultrasonic wave emitted into the fluid and the distance of the ultrasonic propagation path, and the ultrasonic attenuation rate is calculated separately from this detected value for a known scale thickness under the same measurement conditions. By performing calculations using the calibrated value of the ratio, it is possible to measure the thickness of the scale attached to the inside of the pipe to be measured.
次にこの発明の実施例を図面に基づいて説明する。第1
図はこの発明の原理図、第2図にこの発明を実施するた
めの具体的な実施例の構成図、第3図は第2図の配置断
面図を示すものであり、各図において1は流体が通流す
る管、2は管内部に発生して管壁に堆積したスケール、
3は管内を通流するする流体、4a、 4bは2組の超
音波発信子、5a、 5bは前記の発信子4a、 4b
と対向して対をなす超音波受信子であり、発信子4a+
4bおよび受信子5a、 5bはそれぞれ管lの外壁
との間に所定の間隙りを設定して管の両側に対向配置し
、かつ発信子4a、 4bと管1との間および受信子5
a、 5bと管との間の音響接合条件を一定とするため
に前記間隙は管1内を通流する流体と同種の液体である
音響接合液で満たされている。また記号JI+ Jzは
超音波の伝搬経路、Sa、 Sbは管内に付着堆積した
スケール2の厚さ、Dは管の内径、dは管内にスケール
が付着している場合の流路有効径、f+、 fzはそれ
ぞれ発信子4a+ 4bの超音波送信周波数を表してい
る。
まず第1図によりこの発明による測定方法の原理を説明
する。図における2つの超音波伝搬経路1、および1.
を蒲じて図示の発信子4a、 4bから受信子4a+
4bへ向けて超音波を発射すると、発信音圧と受信音圧
との間に次式が成立する。
In(r+/Io) = lnK −A (Ss 十
Sb )L” −−−filIn(It/I。)−In
K −A (Sa +sb )fg” −−−−−−
−−f21但し、Ioは送信音圧、L、Itは送信周波
数fl+f、に対応した受信音圧、Kは音圧透過率、A
は超音波の減衰定数の係数、Xは周波数の減衰への影響
を表す係数である。
上記の(11,(21式で音圧透過率には、スケール2
の音響インピーダンスがあらかじめ判っていると流体3
の音響インピーダンスから計算によって求められるので
既知数である。したがって弐(kl、 (21から次式
が成立する。
但し、αz=ft/f*である。なお上記において超音
波に2通りの周波数を使用するのは、周波数が高くなる
と超音波の減衰が増加することから、あらかしめ2i1
1りの周波数の超音波を設定するように・して対象とな
る測定範囲をカバーし、併せてスケールの減衰率の較正
値の信鯨性をあげるためである。
上記の式(4)においてAf♂は単位長さ当たりの減衰
率、Sa + Sbはスケール厚さを表しており、ここ
であらかじめ既知のスケール厚さに付いて発振音圧r、
と受信音圧I、および計算によって求めた音圧i3過率
Kによって式(4)からスケールの減衰率の較正値を算
出して用意しておく。
次に被測定対象となる管内のスケール厚さを測定するに
は、被測定管について前記と同様な測定操作を行うこと
により次式によってそのスケールの厚さを求めることが
できる。
〔Ar1” )
(Art″)
ここでD−dはスケールの厚さくSa+Sb)を、CA
r+葺)、 (Ar1”] は前記した既知のスケー
ルに付いて求めたスケールの減衰率の較正値を表す。ま
た式(5)は周波数f11式(6)は周波数f2でスケ
ールの減衰率を較正した場合である。したがって式(5
)あるいは(6)により、被測定管に付いての実際の測
定時には超音波の受信音圧検出値と音圧透過率からIn
(にto/r+)、 In(Klo/Ig)の項を割り
出し、この値とあらかじめ既知のスケールに付いて求め
た減衰率較正値との演算により被測定管について管内に
付着しているスケール厚さ[)−dを求めることができ
る。
次に上記の原理によるスケール厚さの測定方法を実施す
るための具体的な装置を第2図に示して説明する。すな
わち第2図の実施例では、管1の外壁上に管を挟んで超
音波発信子4aと受信子5a、および発信子4bと受信
子5bをそれぞれ対とする2組の超音波発信子信子が対
向配備されており、かつそれぞれの発振、受信子は管1
から所定の間隙りを隔てて管上に設面した取付台7に固
定支持した上で第3図のように音響接合液6を満たした
水槽6a内に収容されている。なお超音波の伝搬角度は
管lに対して直角に設定されている。また前記の超音波
発信子4a、 4bはそれぞれ電子回路の発信回路8a
、 8bが接続され、一方の受信子5a、 5bには受
信回路9a、 9b、減衰割合の割出し回路10、演算
回路11、および出力表示部12が接続されている。
なお13は選択切換スイッチである。
上記の回路構成で発信回路8a、 8bによって周波数
fl+ ftの短パルスの電気エネルギーp 、、 p
bを発信子4a+ 4bに印加すると、超音波が伝搬
経路j1およびj tを通って音響接合液6.管lの管
壁、スケールN2および流体3を透過伝搬して受信子5
a。
5bに受信される。また受信子5at 5bで受信され
た超音波の受信信号Q *−Q bは受信回路9at
9bで増幅され、減衰割合割出し回路10で前記した式
(5)。
(6)における減衰割合In(Kl。/II)の項、な
いしはIn(Kl。/■、)の項を割出す、この値は演
算回路12に入力され、ここであらかじめ既知のスケー
ル厚さについて求めた減衰率較正値とで式(51,(6
1による演算を行って被測定管に付着している実際のス
ケール厚さD−dを算出し、その値を表示部13に出力
して表示する。しかもこの場合に超音波発信子および受
信子と管との間の間隙が管内1ii12it液体と同種
の音8I接合液で満たしであるので、発、受信子と管と
の間の音響接合条件が一定に保たれ、発、受信子を直接
管の外壁上に当接した場合のような接触圧による外乱の
影響を受けるおそれがなくて高い測定精度が得られる。
【発明の効果]
以上述べたようにこの発明は、管を挟んでその両側に管
の外壁より所定の間隙を隔てて超音波発信子と受信子と
を対向配置するとともに、該間隙を管内通流の流体と同
種の音響接合液体で満たし、この状態で発信子より受信
子へ向けて流体中に超音波を伝搬してその発信音圧と受
信音圧から超音波の減衰割合を検出し、該検出値とあら
かじめ既知のスケール厚さについて求めた超音波減衰率
の較正値との演算により管内に付着しているスケール厚
さを求めるようしたものであり、これにより従来の測定
技術における欠点を除去して管内に付着したスケールの
厚さを管外から精度よく測定するとができる。Next, embodiments of the present invention will be described based on the drawings. 1st
The figure shows the principle of this invention, FIG. 2 shows the configuration of a specific embodiment for carrying out the invention, and FIG. 3 shows a cross-sectional view of the arrangement of FIG. 2. In each figure, 1 is a A pipe through which fluid flows; 2 is scale generated inside the pipe and deposited on the pipe wall;
3 is a fluid flowing through the pipe; 4a, 4b are two sets of ultrasonic transmitters; 5a, 5b are the transmitters 4a, 4b.
It is an ultrasonic receiver that is paired opposite to the transmitter 4a+.
4b and the receivers 5a, 5b are arranged facing each other on both sides of the tube with a predetermined gap set between them and the outer wall of the tube 1, and between the transmitters 4a, 4b and the tube 1 and the receiver 5.
In order to maintain constant acoustic bonding conditions between the tubes a and 5b and the tube, the gap is filled with an acoustic bonding liquid that is the same type of fluid as the fluid flowing through the tube 1. In addition, the symbol JI+ Jz is the propagation path of the ultrasonic wave, Sa and Sb are the thicknesses of scale 2 deposited inside the tube, D is the inner diameter of the tube, d is the effective diameter of the flow path when scale is attached inside the tube, and f+ , fz represent the ultrasonic transmission frequencies of the transmitters 4a+4b, respectively. First, the principle of the measuring method according to the present invention will be explained with reference to FIG. Two ultrasound propagation paths 1 and 1 in the figure.
The transmitter 4a, 4b shown in the figure is wrapped around the receiver 4a+.
When an ultrasonic wave is emitted toward 4b, the following equation is established between the transmitted sound pressure and the received sound pressure. In(r+/Io) = lnK −A (Ss 1 Sb) L” ---filIn(It/I.) −In
K −A (Sa +sb)fg” −−−−−−
--f21 However, Io is the transmitting sound pressure, L, It is the receiving sound pressure corresponding to the transmitting frequency fl+f, K is the sound pressure transmittance, A
is a coefficient of an ultrasonic attenuation constant, and X is a coefficient representing the influence of frequency on attenuation. In the above equations (11, (21), the sound pressure transmittance has a scale of 2
If the acoustic impedance of fluid 3 is known in advance,
It is a known number because it is calculated from the acoustic impedance of . Therefore, the following equation holds true from 21. However, αz = ft/f*.The reason why two frequencies are used for the ultrasound in the above is that the higher the frequency, the more attenuated the ultrasound is. Since it increases, it is clear that 2i1
This is to set the ultrasonic wave at one frequency to cover the target measurement range and to increase the accuracy of the calibration value of the scale attenuation rate. In the above equation (4), Af♂ represents the attenuation rate per unit length, and Sa + Sb represents the scale thickness, where the oscillation sound pressure r,
A calibration value for the attenuation rate of the scale is calculated and prepared from equation (4) using the received sound pressure I, and the calculated sound pressure i3 pass rate K. Next, to measure the scale thickness inside the pipe to be measured, the same measurement operation as described above is performed on the pipe to be measured, and the thickness of the scale can be determined by the following equation. [Ar1”) (Art”) Here, D-d is the scale thickness (Sa+Sb), and CA
r+fuki), (Ar1”] represents the calibration value of the scale attenuation rate obtained for the above-mentioned known scale.Equation (5) expresses the scale attenuation rate at frequency f11 and expression (6) expresses the scale attenuation rate at frequency f2. This is the case when the calibration is performed. Therefore, the equation (5
) or (6), when actually measuring the pipe to be measured, In
(to/r+) and In(Klo/Ig), and calculate the thickness of the scale attached inside the pipe to be measured by calculating this value and the attenuation rate calibration value calculated in advance for a known scale. It is possible to obtain s[)-d. Next, a specific apparatus for carrying out the method for measuring scale thickness based on the above principle will be described with reference to FIG. 2. That is, in the embodiment shown in FIG. 2, two sets of ultrasonic transmitter elements, each pair consisting of an ultrasonic transmitter 4a and a receiver 5a, and an transmitter 4b and a receiver 5b, are placed on the outer wall of the tube 1 with the tube between them. are arranged facing each other, and each oscillation and receiver is connected to tube 1.
It is fixedly supported on a mounting base 7 installed on the pipe with a predetermined gap from the pipe, and is housed in a water tank 6a filled with an acoustic bonding liquid 6 as shown in FIG. Note that the propagation angle of the ultrasonic waves is set perpendicular to the tube l. Further, the ultrasonic transmitters 4a and 4b each include a transmitting circuit 8a of an electronic circuit.
, 8b are connected to one of the receivers 5a and 5b, and receiving circuits 9a and 9b, an attenuation ratio indexing circuit 10, an arithmetic circuit 11, and an output display section 12 are connected to one of the receivers 5a and 5b. Note that 13 is a selection switch. With the above circuit configuration, the transmitting circuits 8a and 8b generate short pulses of electrical energy p, p, with a frequency fl+ft.
b is applied to the transmitters 4a+4b, the ultrasonic waves pass through the propagation paths j1 and jt to the acoustic bonding liquid 6. The receiver 5 is transmitted through the tube wall of the tube 1, the scale N2, and the fluid 3.
a. 5b. Further, the ultrasonic reception signal Q*-Qb received by the receivers 5at and 5b is transmitted to the receiving circuit 9at.
The equation (5) described above is amplified by the attenuation ratio determining circuit 10. The term of the attenuation ratio In(Kl./II) or In(Kl./■,) in (6) is determined. This value is input to the arithmetic circuit 12, where it is used for the previously known scale thickness. Using the calculated attenuation rate calibration value, formula (51, (6
1 to calculate the actual scale thickness D−d attached to the tube to be measured, and output the value to the display section 13 for display. Furthermore, in this case, the gap between the ultrasonic transmitter and receiver and the tube is filled with the same type of acoustic 8I bonding liquid as the 1ii12it liquid in the tube, so the acoustic bonding conditions between the transmitter, the receiver and the tube are constant. High measurement accuracy can be obtained because there is no risk of being affected by disturbances due to contact pressure, which would occur if the transmitter and receiver were brought into direct contact with the outer wall of the tube. [Effects of the Invention] As described above, the present invention provides an ultrasonic transmitter and a receiver that are disposed opposite to each other with a predetermined gap from the outer wall of the tube on both sides of the tube, and that the gap is used to pass through the tube. It is filled with an acoustic bonding liquid of the same type as the flowing fluid, and in this state, ultrasonic waves are propagated into the fluid from the transmitter to the receiver, and the attenuation rate of the ultrasonic waves is detected from the transmitted and received sound pressures. The thickness of the scale adhering to the inside of the pipe is calculated by calculating the detected value and the calibrated value of the ultrasonic attenuation factor determined in advance for the known scale thickness.This eliminates the drawbacks of conventional measurement techniques. The thickness of the scale that has been removed and adhered to the inside of the tube can be accurately measured from outside the tube.
第1図はこの発明の原理図、第2図はこの発明の測定方
法を実施するための装置の具体的な構成図、第3図は第
2図の配置構成断面図である0図において、
I:管、2ニスケール、3:流体、4a、4b:超音波
発信子、5a、5b:受信子、6:音響接合液、8a、
8b:発信回路、9a、9b:受信回路、1o:ill
側割し回路、11:演算回路、D:管の内径、Sa。
Sb:管内スケールの厚さ、Jl+ jz:超音波の伝
搬経路、f+、tz:超音波の発信周波数。
第1図FIG. 1 is a diagram of the principle of the present invention, FIG. 2 is a specific configuration diagram of an apparatus for carrying out the measuring method of the present invention, and FIG. 3 is a sectional view of the arrangement and configuration of FIG. I: tube, 2 scales, 3: fluid, 4a, 4b: ultrasonic transmitter, 5a, 5b: receiver, 6: acoustic bonding liquid, 8a,
8b: Transmission circuit, 9a, 9b: Receiving circuit, 1o: ill
Side split circuit, 11: Arithmetic circuit, D: Inner diameter of pipe, Sa. Sb: Thickness of the scale inside the pipe, Jl+ jz: Ultrasonic propagation path, f+, tz: Ultrasonic transmission frequency. Figure 1
Claims (1)
波により測定する方法であって、管を挟んでその両側に
管の外壁より所定の間隙を隔てて超音波発信子と受信子
とを対向配置するとともに、つ該間隙を管内通流の流体
と同種の音響接合液体で満たし、この状態で発信子より
受信子へ向けて流体中に超音波を伝搬してその超音波減
衰割合を検出し、該検出値とあらかじめ既知のスケール
厚さについて求めた超音波減衰率の較正値とから演算に
より管内に付着しているスケール厚さを求めるようにし
たことを特徴とする管内スケール厚さの測定方法。1) A method of measuring the thickness of scale formed inside a pipe through which fluid flows using ultrasonic waves, in which an ultrasonic transmitter and a receiver are placed on both sides of the pipe with a predetermined gap from the outer wall of the pipe. are arranged facing each other, and the gap is filled with an acoustic bonding liquid of the same type as the fluid flowing in the pipe, and in this state, the ultrasonic wave is propagated into the fluid from the transmitter to the receiver, and the ultrasonic attenuation rate is reduced. The scale thickness inside the pipe is characterized in that the thickness of the scale adhering to the inside of the pipe is calculated by calculating from the detected value and a calibration value of the ultrasonic attenuation factor calculated in advance for a known scale thickness. How to measure
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19408285A JPS6254113A (en) | 1985-09-03 | 1985-09-03 | Thickness measuring method for scale in pipe |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19408285A JPS6254113A (en) | 1985-09-03 | 1985-09-03 | Thickness measuring method for scale in pipe |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS6254113A true JPS6254113A (en) | 1987-03-09 |
Family
ID=16318656
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP19408285A Pending JPS6254113A (en) | 1985-09-03 | 1985-09-03 | Thickness measuring method for scale in pipe |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6254113A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5524165A (en) * | 1978-08-04 | 1980-02-21 | Merck & Co Inc | Alkyl derivative of cc076 compound |
JPH03188390A (en) * | 1989-12-19 | 1991-08-16 | Touden Kogyo Kk | Measuring method of sticking state of marine life inside piping |
-
1985
- 1985-09-03 JP JP19408285A patent/JPS6254113A/en active Pending
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5524165A (en) * | 1978-08-04 | 1980-02-21 | Merck & Co Inc | Alkyl derivative of cc076 compound |
JPH0238596B2 (en) * | 1978-08-04 | 1990-08-31 | Merck & Co Inc | |
JPH03188390A (en) * | 1989-12-19 | 1991-08-16 | Touden Kogyo Kk | Measuring method of sticking state of marine life inside piping |
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