RU2249802C2 - Method and device for detecting leakage site in pipeline - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method comprises receiving noise of discharging jet with the use of two acoustical pickups, converting the noise into voltage, digitization, filtering, and analyzing. The acoustical pickups are set at one site of the pipeline. One of the pickups receives acoustical waves, which propagate over the shell of the pipeline. The second one receives acoustical waves which propagate in the ambient fluid. The signal received are analyzed to determine co-spectra, and the values of the real and imaginary parts of the co-spectra indicate time lag between the signals which propagate in two fluids.

EFFECT: enhanced reliability of detecting.

3 cl, 1 dwg

Description

The invention relates to a device for determining the location of a leak of liquid or gas in pipelines and is intended to determine the coordinates of a leak in remote places of gas pipelines and oil pipelines.

There is a known method for detecting holes in a pipe from Japanese Patent No. 4-184133, according to which the noise of the jet flowing out of the hole (leak noise) is received by acoustic sensors located at both ends of the pipe, the signals from which are visualized on the display and compared. If the signals are equal, then the hole is in the middle part between the sensors. If the signal from one of the sensors is much larger than the other, then the hole is located closer to this sensor.

A device that implements this method contains two paths, each of a series-connected acoustic sensor, amplifier, display.

The disadvantages of the method and the analog device is the lack of accuracy in determining the location of the leak, as well as the inability to install the second sensor in inaccessible places.

The closest in technical essence to this proposal is US patent No. 5.058.419 for a method and apparatus for determining the location of a sound source. According to this method, to determine the coordinates of a leak in a pipeline, the sound of this pipe leak is detected at two points 300 meters away from each other and the location of the sound source is calculated from the delay time. The propagation velocity necessary for this is calculated based on the parameters of the liquid in the pipe, the materials and the shape of the pipe according to the standards of the American Water Association AWWA C 401-77 and ANSG / AWWA C 403-78.

The device that implements the prototype method, contains two receiving paths, each of a series-connected acoustic sensor, amplifier, filter, analog-to-digital converter, also contains a personal computer, the first and second inputs of which are connected to the outputs of the analog-to-digital converters of the first and second paths.

The disadvantages of the method and the prototype device are, firstly, the need to receive signals at two remote points, which is associated with the need to create special electrical communications, and secondly, the calculation of the speed of sound through the pipe cannot be accurate due to the different fastening of the pipe on the highway, thirdly, it is not possible to determine the place of a leak in places inaccessible to observation.

The objective of the invention is the provision of determining the location of a leak from one point on the pipeline route.

The technical result of the invention is to simplify the method and device for determining the location of a leak due to the lack of the need to measure at two points spaced a considerable distance and connected by either cable or other means of transmitting information. In addition, the second measurement point is not always available, that is, it becomes possible to determine the coordinates of the leak in places inaccessible to observation.

The specified technical result is achieved in that in a method for determining the location of a leak in a pipeline, comprising receiving noise signals leak by the first and second acoustic sensors, converting these noise signals to leak into electrical signals, filtering and sampling the electrical signals and determining the location of the leak by the delay time of noise signals leaks received by the first and second acoustic sensors, new features are introduced, namely: the first and second acoustic sensors are installed nearby on the pipeline, so that the first ustichesky sensor has acoustic contact with the pipeline and acoustically shielded by the acoustic waves in the surrounding medium conduit, and the second - acoustically shielded by the acoustic waves propagating through the pipeline, a pre-fixed distance R _H from the sensors is excited in the pipeline and in its environment artificial noise signal receive a noise signal propagating through the pipeline by the first acoustic sensor, a noise signal propagating through the environment surrounding the pipeline in torym acoustic sensor, electrical signals of the first and second acoustic sensors after filtering and sampling subjected vzaimospektralnoy processing, the data on the real and imaginary parts of the cross spectrum, the value R _and and the propagation velocity of acoustic waves in the medium are the propagation velocity of the group of waves in a pipe with a signal leaks produce inter-spectral processing of the filtered, discretized leak signals received in the first and second transformed into electrical signals acoustic sensors, the delay time of leak noise signals received by the first and second acoustic sensors determines data on the real and imaginary parts of the mutual spectrum of leak noise signals, after which the location of the leak is determined taking into account the propagation velocity of acoustic waves in the medium and the velocity of group waves in the pipeline.

до верхней частоты

, где U - скорость струи течи, D - диаметр минимального отверстия течи, подлежащей обнаружению.The optimal result is obtained if filtering is carried out in the frequency band from the lower frequency.

to high frequency

where U is the speed of the leak, D is the diameter of the minimum hole of the leak to be detected.

To ensure this technical result, the following new features are introduced into the device for determining a leak in the pipeline, including the first and second receiving paths, each of which contains the first and second acoustic sensors in series, respectively, an amplifier, a filter, and an analog-to-digital converter, namely: the first sensor has acoustic contact with the pipeline and is acoustically shielded from acoustic waves into the surrounding medium, and the second acoustic sensor is acoustically shielded the van from acoustic waves propagating through the pipeline, the device contains a series-connected reciprocal spectrum analyzer, the first and second inputs of which are connected to the outputs of the analog-to-digital converters of the first and second receiving paths, respectively, the distance calculation unit and the indicator also contains a group wave memory in the pipeline and in the environment of the pipeline, the input of which is connected to the second output of the distance calculation unit, and the output to the second input of the unit calculating the distance and propagation velocity of group waves in the pipeline, there is also a control unit whose sync inputs and clock outputs are connected to analog-to-digital converters, with a mutual spectrum analyzer, with a unit for calculating the distance and propagation velocity of group waves in the pipeline, with a memory unit for propagation velocities of group waves in the pipeline and in the environment of the pipeline and with the indicator, also contains an artificial source of acoustic signal, acoustically connected with the first ak a static sensor through the pipeline, and with a second acoustic sensor through the surrounding environment.

The invention is illustrated in the drawing, which shows a block diagram of a device for implementing the proposed method for determining the location of a leak in the pipeline.

The device for determining the place of a leak in the pipeline has two paths containing serially connected acoustic sensors 1.1 and 1.2, amplifiers 2.1 and 2.2, filters 3.1 and 3.2, analog-to-digital converters 4.1 and 4.2. It contains a series-connected mutual spectrum analyzer 5, the first and second inputs of which are connected to the outputs of analog-to-digital converters 4.1 and 4.2, a unit 6 for determining the distance and propagation velocity of group waves in the pipeline, indicator 7. It also contains a unit 8 for memory of propagation velocities of group waves in the pipeline and in the environment of the pipeline environment, the input of which is connected to the second output of the block 6, and the output is connected to the second input of the distance determination unit 6. The control unit 9 has clock inputs and clock outputs connected to blocks 4.1 and 4.2, blocks 5, 6, 8. 7. There is also an artificial signal source 10.

[А.С.Никифоров. Акустическое проектирование судовых конструкций. Справочник. -Л.: судостроение, 1990.-c.l7]The method provides the following sequence of operations provided by the operation of the device. First, the group velocity, U, of the propagation of the acoustic signal through the pipe, is determined experimentally. The nature of the waves propagating through the cylindrical pipe substantially depends on the dimensionless frequency -

[A.S. Nikiforov. Acoustic design of ship structures. Directory. -L .: shipbuilding, 1990.-c.l7]

. Обычно радиусы магистральных трубопроводов

. Поэтому можно для стальных трубопроводов с таким R_сp принятьwhere R _cp is the average radius of the pipe, C _pp - the velocity of the longitudinal wave in the plate equal to the thickness of the pipe. For steel pipe

. Usually the radii of trunk pipelines

. Therefore, it is possible to accept for steel pipelines with such R _cp

those. at frequencies f _cr > 1330 Hz, bending, longitudinal and shear vibrations can occur in the pipe. In this case, bending vibrations have a propagation velocity

Longitudinal wave velocity

where E, σ, ρ are Young's, Poisson's moduli and density of the pipe material. Shear wave velocity

where G is the shear modulus.

For steel: Young's modulus E = 21 · 10 ¹⁰ Pa, shear modulus G = 8.14 · 10 ¹⁰ Pa, Poisson's ratio σ = 0.29, density ρ = 7.8 · 10 ³ kg m ^-3 .

If there is a liquid in the pipe, the shelling mass of this liquid is added to the mass of the pipeline at a frequency below f ₀ equal to

where C ₀ is the speed of sound in the fluid filling the pipeline.

Видно, что на частотах, большихWhen the pipeline is in a liquid, a cracking mass [E. Bored. The basics of acoustics. -M .: IL, 1958, volume 1, -617]

It can be seen that at frequencies higher

Acoustic waves with different propagation speeds move through the pipeline. Therefore, the group propagation velocity of the acoustic signal through the pipe must be determined experimentally, especially since there may be different pipe fastening in the duker.

To do this, the following operation is introduced into the method: at a known distance R ₀ from the location of the acoustic sensors, artificial acoustic excitation is created in the pipe and in the medium with frequencies lying in the range from f _n to f _{in the} filters.

The artificial noise signals are received by the first and second acoustic sensors 1.1 and 1.2, the first is acoustically isolated from noise in the medium, and the second is receiving noise in the medium.

Using filters 3.1 and 3.2, filter the received signals of artificial noise emission.

The filters are selected so as to ensure that the noise of the jet is separated from a certain minimum damage, for example, with a diameter of D = 5 · 10 ^-3 m. The maximum noise of the jet of a leak escaping from the pipeline is observed at the Strouhal number

where f is the frequency in Hz, U is the jet velocity in m / s ^-1 . The main noise energy of the jet is concentrated in the range from fD = 0.21 to

[A.G. Munin, M.A. Shchepochkin. Sound power spectrum of a subsonic jet. - Acoust magazine, vol. XVIII, 1972, issue 2, p. 292-298].

а верхнюю границу фильтра

Therefore, the lower limit of the filter can be selected

and the upper limit of the filter

They amplify the filtered signals received by the sensors 1.1 and 1.2 with the help of amplifiers 3.1 and 3.2, and convert them into digital signals using the ADCs 4.1 and 4.2.

где G₀(f) - энергетический спектр искусственного шума на единичном расстоянии; t_3,и - время задержки искусственного сигнала в среде, относительно сигнала, распространяющегося по трубе.The mutual spectrum of these signals is determined

where G ₀ (f) is the energy spectrum of artificial noise at a unit distance; t _{3, and} is the delay time of the artificial signal in the medium, relative to the signal propagating through the pipe.

The delay time is determined by the frequencies of zero values of the real or imaginary parts of the mutual spectrum or in the form

где Im[•], Re[•] - символы мнимой и действительной частей.

where Im [•], Re [•] are symbols of the imaginary and real parts.

где, С_тр, С_ср - соответственно скорости распространения акустических волн по трубопроводу и в окружающей среде. По алгоритму в виде последовательности приведенных выше выражений (1), (2), (3), (4), (5), (6), (7), (8), (9) и при известных значениях R_o, t₃ и С_cр нетрудно найти:The propagation velocity of the group waves propagating through the pipeline is determined. Given that the delay time between artificially generated signals:

where, C _Tr , C _cp - respectively, the propagation velocity of acoustic waves through the pipeline and in the environment. According to the algorithm in the form of a sequence of the above expressions (1), (2), (3), (4), (5), (6), (7), (8), (9) and for known values of R _o , t ₃ and C _cp it is easy to find:

which is carried out in block 6.

The radiation of the artificial signal is stopped, the signals received by the sensors 1.1 and 1 2 are monitored, and when leak signals appear, they carry out the sampling, filtering, amplification, and cross-spectral processing of the leak noise signals according to the same procedure as for artificial radiation signals.

The delay time is determined by the frequencies of zero values of the real or imaginary parts of the mutual spectrum or in the form

where Im [•], Re [•] are symbols of the imaginary and real parts.

Find the distance r to the leak at the delay time t ₃ between the acoustic signals propagating through the pipe and in the medium, in the form

Cross-spectral analysis is carried out in block 5. The determination of the distance r is performed by the expressions (10), (11), (12) in block 6. Data on C _mp and C _cp are recorded in the memory block 8. The measurement results of the value of r are displayed on indicator 7. The control unit 9 provides synchronization of the operation of the device.

The construction of device blocks is known from practice. Shielding of acoustic sensors is known, for example, from the book of V.E. Glazanov. Shielding sonar antennas. -L.: Shipbuilding, 1986.- 148 p.

As an artificial source, an electrodynamic vibration source can be used (see, for example, V.E. Golsky. Automobile vibroacoustics. -M. Mechanical Engineering, 1988.-p.73) or a hammer emitter - a standard vibration source (GOST 15116-79, standard ISO 140).

Thus, the claimed method and device realize the required technical result.

Claims (3)

1. A method for determining the location of a leak in a pipeline, comprising receiving noise signals leak from the first and second acoustic sensors, converting these noise signals to leak into electrical signals, filtering and sampling electrical signals and determining the location of the leak by the delay time of noise leak signals received by the first and second acoustic sensors, characterized in that the first and second acoustic sensors are installed on the pipeline side by side, the first acoustic sensor has acoustic contact with the pipeline and acoustic it is shielded from acoustic waves in the environment of the pipeline, and the second is acoustically shielded from acoustic waves propagating through the pipeline, previously at a fixed distance R _h from the sensors, an artificial noise signal is excited in the pipeline and in its environment, an artificial noise signal propagating through the pipeline is received the first acoustic sensor, a noise signal propagating through the surrounding medium by the second acoustic sensor, the electrical signals of the first and the second acoustic sensors after filtering and sampling are subjected to inter-spectral processing, according to the real and imaginary parts of the mutual spectrum, the value of R _h and the propagation velocity of acoustic waves in the medium, the propagation velocity of group waves in the pipeline is found, in the presence of a leak, they produce inter-spectral processing converted to electrical signals filtered, discretized leak signals received by the first and second acoustic sensors, delay time of noise leak signals, n Accepted by the first and second acoustic sensors, it is determined from the data on the real and imaginary parts of the mutual spectrum of noise signals of the leak, after which the location of the leak is determined taking into account the propagation velocity of acoustic waves in the medium and the velocity of group waves in the pipeline. 2. The method for determining the location of a leak according to claim 1, characterized in that the filtering is carried out in the frequency band from the lower frequency

to high frequency

where U is the speed of the leak, D is the diameter of the minimum hole of the leak to be detected. 3. A device for determining a leak in a pipeline, including the first and second receiving paths, each of which contains a first and second acoustic sensor, respectively connected in series, an amplifier, a filter and an analog-to-digital converter, characterized in that the first acoustic sensor has acoustic contact with the pipeline and is acoustically shielded from acoustic waves in the environment surrounding the pipeline, and the second acoustic is acoustically shielded from acoustic waves propagating through the pipeline, a serial analyzer of the mutual spectrum is introduced into the device, the first and second inputs of which are connected to the outputs of the analog-to-digital converters of the first and second receiving paths, respectively, a unit for calculating the distance and propagation velocity of group waves in the pipeline and an indicator, a memory unit for propagating group wave velocities pipeline and in the environment of the pipeline environment, the input of which is connected to the second output, and the output to the second input of the unit for calculating the distance and speed the propagation of group waves in the pipeline, a control unit has also been introduced, the sync inputs and sync outputs of which are connected to an analog-to-digital converter, with a reciprocal spectrum analyzer, with a unit for calculating the distance and propagation velocity of group waves in the pipeline, with a memory unit for the propagation velocities of group waves in the pipeline and the environment surrounding the pipeline and with an indicator, an artificial source of acoustic signal is also introduced, which is acoustically connected to the first acoustic sensor through the pipeline, and with About the second acoustic sensor - through the environment surrounding the pipeline.