WO2012029484A1 - Leak detection device for liquid transportation pipeline, and method therefor - Google Patents

Leak detection device for liquid transportation pipeline, and method therefor Download PDF

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Publication number
WO2012029484A1
WO2012029484A1 PCT/JP2011/067563 JP2011067563W WO2012029484A1 WO 2012029484 A1 WO2012029484 A1 WO 2012029484A1 JP 2011067563 W JP2011067563 W JP 2011067563W WO 2012029484 A1 WO2012029484 A1 WO 2012029484A1
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Prior art keywords
reflected wave
leak detection
pulse signal
signal
sampling
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PCT/JP2011/067563
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French (fr)
Japanese (ja)
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和幸 中野
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株式会社潤工社
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Publication of WO2012029484A1 publication Critical patent/WO2012029484A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
    • G01M3/165—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means by means of cables or similar elongated devices, e.g. tapes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
    • G01M3/18—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators

Definitions

  • the present invention relates to a leak detection device for a liquid transportation pipeline such as an oil pipeline. Specifically, a change in characteristic impedance of a detection cable line such as a coaxial cable is detected by detecting a reflected wave of a pulse signal incident on the detection cable, and a defective portion of the detection cable and a liquid transport pipeline are detected.
  • the present invention relates to a leak detection device that identifies a leak location of a short time.
  • a TDR method (Time Domain Reflectometry, time domain reflection method) is known as one of methods for measuring the characteristic impedance of a coaxial cable.
  • detectors to which the TDR method is applied there are a detector that detects an abnormal portion of a coaxial cable, a leak detector that uses the coaxial cable as a detection cable, and the like.
  • a leak detection device applying the method (see Patent Documents 1 to 3).
  • This leakage detection device includes a detection cable configured by a coaxial cable, a pulse signal generator that generates a pulse signal incident from one end of the detection cable, and a detector that detects a reflected wave of the pulse signal from the detection cable And have.
  • the detection cable is arranged below the liquid transport pipeline, etc., and the insulator that is arranged between the conductors in the detection cable is made of a material whose characteristic impedance changes when the liquid to be detected infiltrates or penetrates.
  • a terminator having an impedance equivalent to the characteristic impedance of the detection cable is connected to the other end of the detection cable so as to be matched with the characteristic impedance.
  • the pulse signal incident on the detection cable does not generate a reflected wave.
  • the liquid leaks from the liquid transport pipeline or the like the liquid leaking from the pipeline penetrates the detection cable, and the characteristic impedance of the penetrated portion changes.
  • a pulse signal is incident on the detection cable, a reflected wave is generated before and after the portion where the characteristic impedance has changed due to liquid infiltration.
  • the detector detects leakage by detecting this reflected wave.
  • the leak location is calculated from the measured value of the time from when the pulse signal is incident on the detection cable until the reflected wave is detected and the pulse signal propagation time of the detection cable. be able to.
  • a conventional leak detection apparatus using the TDR method employs a method of measuring the reflected wave at one point each time a pulse signal is incident, thereby grasping the characteristic impedance at each measurement point. This is because the attenuation of the reflected wave depends on the propagation distance between the measurement point and the detection point, and the amplification factor of the reflected wave is different for each measurement point.
  • the number of measurements increases as the length of the pipeline to be measured increases, and as the interval between the measurement points is narrowed to increase the resolution of the measurement value.
  • the processing time was increased in proportion to the number of times.
  • an object of the present invention is to provide a leak detection device capable of solving the above-described problems.
  • the present invention shortens the processing time by employing an amplification unit that amplifies the reflected wave at a specific sampling period based on data representing the correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave.
  • An object is to provide a leak detection device.
  • a leak detection device of the present invention is a device that detects a liquid leak from a liquid transport pipeline by detecting a reflected wave of a leak detection pulse signal incident on a leak detection cable.
  • a leak detection cable that is laid along the pipeline and changes its characteristic impedance when liquid leaked from the pipeline permeates, and a leak detection pulse signal generator that generates a leak detection pulse signal incident on the leak detection cable
  • a storage unit for storing data representing the correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave, and the reflected wave with respect to the leak detection pulse signal is amplified in synchronization with the sampling signal repeated at a predetermined sampling period.
  • a gain amplifier that changes the gain of the reflected wave based on the data, and a gain amplifier; In synchronization with the pulling signal, a reflected wave is amplified for one leak detection pulse signal sampled a plurality of times, and having an A / D converter for converting the reflected wave sampled digital signal.
  • the liquid transport pipeline A leak detection device that can detect the presence or absence of liquid leak in a short time can be realized.
  • FIG. 1 shows an example of a leak detection apparatus according to the present invention.
  • the leak detection device 1 includes a detection sensor 11 and a signal processing unit 2.
  • the detection sensor 11 is disposed below the liquid transport pipeline 100 that transports a liquid such as petroleum.
  • the signal processing unit 2 inputs a pulse signal to the detection sensor 11, processes a reflected wave generated when the leaked liquid penetrates the detection sensor 11, detects a leak in the liquid transport pipeline 100, and detects the leak location Identify.
  • FIG. 2 shows an example of the detection cable 11 employed in the leak detection apparatus 1 according to the present invention.
  • the detection cable 11 includes an inner conductor 11a and an outer conductor 11b.
  • the inner conductor 11a can be formed of bare annealed copper or the like, and the outer conductor 11b is braided by tin-plated annealed copper wire, or braided by mixing tin-plated annealed copper wire and porous PTFE (polytetrafluoroethylene). Can be formed.
  • one end of the internal conductor 11 a is connected to the signal processing unit 2, and the other end is preferably connected to the terminator 13.
  • the impedance of the terminator 13 can be equivalent to the characteristic impedance of the detection cable 11. Accordingly, it is possible to prevent a reflected wave from being generated when a pulse signal is incident from one end of the detection cable.
  • the outer conductor 11b is grounded to the ground.
  • an inner protective layer 11c and a detection layer 11d are disposed between the inner conductor 11a and the outer conductor 11b of the detection cable 11.
  • An outer protective layer 11e and a protective braid 11f are disposed on the outer periphery of the outer conductor 11b.
  • the outer protective layer 11e and the detection layer 11d disposed on the outer periphery of the outer conductor 11b are formed of porous PTFE tape. As known to those skilled in the art, porous PTFE has good water repellency, while having the property of easily penetrating oils.
  • the external protective layer 11e, the external conductor 11b, and the detection layer 11d including a porous PTFE tape as a material can transmit oil without allowing moisture such as rainwater to permeate.
  • PTFE has the characteristic that the dielectric constant changes by containing oils.
  • the characteristic impedance of the detection cable 11 changes in the detection layer 11d formed between the inner conductor 11a and the outer conductor 11b when oil penetrates.
  • the porous PTFE tape employed for the material such as the detection layer 11d can be various porous PTFE tapes having different air contents in the porous material. By changing the air content in the porous material, a porous PTFE tape having a desired dielectric constant can be formed.
  • the inner protective layer 11c is formed of a resin such as PFA (perfluoroalkoxyalkane) and can prevent oils from penetrating into the inner conductor 11a.
  • the detection cable 11 and the signal processing unit 2 can be directly connected, but preferably, a dummy cable 15 can be inserted between the detection cable 11 and the signal processing unit 2. This is because when the dummy cable 15 is not inserted, there is a possibility that the incident pulse signal and the reflected wave are superimposed and the reflected wave cannot be detected.
  • the length of the dummy cable is determined by the pulse width of the input leakage detection pulse. For example, the length of the dummy cable can be set to 100 [m].
  • a safety barrier 110 can be disposed between the liquid transport pipeline 100 and the detection cable 11.
  • the safety barrier 110 has a function of preventing a combustible liquid such as petroleum leaking from the liquid transport pipeline 100 from igniting due to heat generated by the detection cable 11 or the like.
  • the signal processing unit 2 includes a central processing unit (CPU) 21, a storage unit 23, a pulse generation unit 31, a pulse width control unit 33, an I / O unit 41, and a digital-analog conversion unit (DAC) 51.
  • the CPU 21 is connected to the storage unit 23, the pulse generation unit 31, the pulse width control unit 33, and the like, and controls each element.
  • the pulse generation unit 31 generates a pulse signal based on the control of the CPU 21, provides the pulse signal to the pulse width control unit 33 that generates a signal incident on the detection cable 11, and controls the gain amplifier 53 that amplifies the reflected wave. This is provided as a sampling signal to the CPU 21 and the ADC 61 that converts the reflected wave into digital data.
  • the pulse width control unit 33 changes the cycle of the pulse signal generated by the pulse generation unit 31 and the pulse width by a frequency divider circuit or the like, and generates a leak detection pulse signal suitable for input to the detection cable 11. .
  • the leakage detection pulse signal may have a pulse width of about 200 [ns] to 250 [ns].
  • the leak detection pulse signal generated by the pulse width control unit 33 is transmitted to the detection cable 11 via the I / O unit 41.
  • the leakage detection pulse signal incident on the detection cable 11 is absorbed by the terminator 13 when there is no leakage in the liquid transport pipeline 100 and the characteristic impedance of the detection cable 11 does not match in the line direction. No reflected wave is generated.
  • the gain amplifier 53 detects the leakage point based on the gain table stored in the storage unit 23 that is read out via the DAC 51 for each sampling period of the sampling signal generated by the pulse generation unit 31.
  • the reflected wave is amplified to an appropriate size according to the above.
  • the reflected wave amplified by the gain amplifier 53 is sampled by the ADC 61 at the sampling period of the sampling signal generated by the pulse generator 31 and converted into a digital signal.
  • the signal digitized by the ADC 61 is stored in the storage unit 23 and also provided to the display device 113 and the storage device arranged outside the data processing unit 2 via the data I / O unit 71.
  • the leakage detection pulse signal and the time tc [s / m] for which the reflected wave moves by 1 m in the detection cable 11 are calculated.
  • the propagation speed Vc of the electromagnetic signal in the material is Indicated by
  • c is the speed of light in vacuum of 2.99 ⁇ 10 8 [m / s]
  • ⁇ is relative permeability
  • ⁇ is relative permittivity.
  • the leak detection pulse signal and the time tc during which the reflected wave moves 1 m through the detection cable 11 can be expressed by the reciprocal of the signal propagation velocity Vc, tc is Indicated by
  • the relative permeability ⁇ is 1, and assuming that the relative dielectric constant ⁇ of the porous PTFE used for the detection layer of the detection cable 11 is 1.5
  • the leakage detection pulse signal is passed through the detection cable 11.
  • the time tc when the reflected wave travels 1 m is It becomes.
  • the time ⁇ t [ns] from when the leakage detection pulse signal is incident from the incident end of the detection cable 11 until the reflected wave reflected at a point away from L [m] returns.
  • the pulse frequency generated by the pulse generator 31 is 31.25 [MHz] and the detection cable 11 has porous PTFE having a relative dielectric constant ⁇ of 1.5. That is, it is assumed that the sampling frequency generated by the pulse generator 31 corresponds to sampling the detection cable 11 every 4 [m].
  • the detection cable 11 having other pulse frequency and relative dielectric constant ⁇ is used.
  • the gain amplifier 53 Based on the gain table stored in the storage unit 23, the gain amplifier 53 amplifies the reflected wave with an appropriate amplification factor according to the distance from the incident end.
  • the gain table stored in the storage unit 23 stores data indicating the correlation between the distance between the end where the leak detection pulse signal is incident and the measurement point, that is, the propagation distance of the reflected wave and the attenuation of the reflected wave. Is done.
  • the CPU 21 reads the data stored in the gain table at the cycle of the sampling signal generated by the pulse generator 31 and provides it to the DAC 51 as a control signal for the gain amplifier 53.
  • This control signal corresponds to a control signal for controlling the gain of the gain amplifier 53.
  • the gain amplifier 53 amplifies the reflected wave with an appropriate gain according to the propagation distance of the reflected wave. It is.
  • data corresponding to a control signal for controlling the gain of the gain amplifier 53 can be stored, and an actual measurement value such as the attenuation rate of the reflected wave for each propagation distance of the reflected wave can also be stored.
  • the storage unit 23 stores data indicating the correlation between the stored actual measurement value and the gain of the gain amplifier 53, and the CPU 21 calculates an appropriate gain based on these data. .
  • the interval between the measurement points of the reflected wave attenuation rate stored in the gain table can be a distance interval synchronized with the sampling period.
  • the sampling period of the pulse signal of the pulse generation unit 31 corresponds to every 4 [m]
  • the gain table interval can be set every 4 [m]. Note that the correspondence between the propagation distance of the physical reflected wave and the distance corresponding to the amplification value stored in the gain table depends on the length of the dummy cable and the location of the leak detection device when installing the leak detection device. And the installation conditions such as the distance to the detection target pipeline.
  • the gain amplifier 53 can have two modes: a disconnection of the detection cable 11 or a disconnection / short-circuit detection disconnection / short-circuit detection test mode for detecting a short circuit, and a leak detection mode for detecting a liquid leak in the liquid transport pipeline. . Since the reflected wave generated at the time of disconnection or short circuit has an amplitude several times larger than the reflected wave generated at the time of leakage, there is a possibility of damaging the amplification element inside the gain amplifier 53 and an electronic circuit element such as the ADC 61. It is.
  • the disconnection / short circuit detection test mode can be executed before the leakage detection mode is executed.
  • FIG. 3 shows an example of the gain amplifier 53 having two modes of a short circuit detection test mode and a leak detection mode.
  • the reflected wave input from the I / O unit includes a signal provided directly to the multiplexer 56 via the buffer 54, and a signal provided to the multiplexer 56 via the amplification element 55. Distributed to.
  • the multiplexer 56 provides the former to the amplification element 57 in the disconnection / short-circuit detection test mode, and provides the latter to the amplification element 57 in the leakage detection mode.
  • the amplifying element 57 amplifies the reflected wave based on a control signal generated from the gain table stored in the storage unit 23 via the DAC 51.
  • the reflected wave amplified by the amplifying element 57 is provided to the ADC 61 via the buffer 58.
  • the reflected wave is sampled in the ADC 61 at the sampling signal cycle generated by the pulse generator 31 and converted into a digital signal. Since both the digital conversion in the ADC 61 and the amplification in the gain amplifier 53 are executed in the sampling cycle of the sampling signal generated by the pulse generation unit 31, both processes are executed in synchronization. Further, the ADC 61 can have a function capable of preventing an input of an unnecessary signal to the ADC 61 such as a signal having a large amplitude when an ADC input cutoff signal is input. By having such a function, the ADC 61 can avoid a signal having a large amplitude such as a reflected wave generated at the time of disconnection or short circuit.
  • FIG. 4 is a diagram illustrating an example of a timing chart in the present embodiment.
  • the sampling signal is a pulse signal generated by the pulse generator 31 shown in FIG.
  • the period of the sampling signal depends on the dielectric constant ⁇ of the detection layer of the detection cable 11 and the distance between measurement points. For example, when the relative dielectric constant ⁇ of the detection layer of the detection cable 11 is 1.5 and the distance between measurement points is 4 [m], the period of the sampling signal can be 32 [ns].
  • the distance of 0 [m] to 32 [m] added to the sampling signal is the propagation distance of the reflected wave.
  • the 0 [m] point is determined based on installation conditions such as the length of the dummy cable to be inserted, the installation location of the leak detection device, and the distance between the pipeline to be detected.
  • the leakage detection pulse signal is formed by, for example, dividing the sampling signal generated by the pulse generator 31 by the pulse width controller 33 shown in FIG. In the example shown in FIG. 4, the pulse width of the leak detection pulse signal has a length corresponding to eight cycles of the sampling signal.
  • the ADC input cut-off signal is a signal that cuts off the input of the ADC 61 so that an unexpected waveform such as a waveform having a large amplitude is not input to the ADC 61.
  • the leakage detection pulse signal is output from the pulse width control unit 33 and during an appropriate time after the leakage detection pulse signal is output so that the leakage detection pulse signal is not input to the ADC 61.
  • the reflected wave is a diagram schematically showing an analog signal observed at the input end of the ADC 61.
  • a waveform indicated by an arrow A is a part of a leak detection pulse signal input via a protection diode, and an amplitude is about 0.5 [V].
  • the waveform indicated by arrow B is a reflected wave of the leak detection pulse signal.
  • the characteristic impedance of the detection cable 11 changes due to liquid leakage from a liquid transport pipeline or the like, a reflected wave is generated.
  • an example in which liquid leakage occurs between 16 [m] and 24 [m] is shown.
  • the reflected wave digitally converted by the ADC 61 is stored as processing data in the storage unit 23 or the like.
  • the processing data stored in the storage unit 23 can be displayed as a waveform graph or the like on the display device 113 such as an LCD display device connected to the leak detection device 1 via the data I / O unit 71.
  • the inspector can determine the presence or absence of liquid leakage in the liquid transport pipeline by inspecting this display. Further, by comparing the reference data stored in the storage unit 23 or the storage device 115 with the processing data, it is possible to determine the presence or absence of liquid leakage in the liquid transport pipeline.
  • the reference data may be created based on the measured value measured when the leak detection apparatus 1 is installed, or may be created based on the average value of the latest plurality of processing data.
  • a predetermined threshold value may be further used when determining the presence or absence of liquid leakage. For example, the presence or absence of liquid leakage can be determined by comparing the maximum difference value between the processing data and the reference data with a predetermined threshold value.
  • an average value of a plurality of processing data may be used. This is to eliminate the influence of irregular noise such as thermal noise by using the average value of a plurality of processing data.
  • the leak detection apparatus 1 reads the gain table stored in the storage unit 23 at a predetermined sampling period, and gives the reflected wave an appropriate amplification factor according to the propagation distance of the reflected wave.
  • a plurality of reflected waves can be detected with respect to the leakage detection pulse signal. For example, when sampling reflected waves every 4 [m], it is possible to detect 250 reflected waves per 1000 [m] for one leak detection pulse signal. For this reason, in the leak detection apparatus 1 which concerns on this invention, compared with the conventional leak detection apparatus which detects one reflected wave with respect to one leak detection pulse signal, detection time can be shortened significantly.
  • a leak detection pulse signal incident on the detection cable 11 is generated using the signal generated by the single pulse generation unit 31, and the gain amplifier 53 and the ADC 61 are also generated. Therefore, it is easy to control the pulse signal and the reflected signal, and there is an advantage that the number of constituent elements can be reduced.
  • step 101 the CPU 21 generates a pulse signal having a predetermined period. Based on this pulse signal, a leak detection pulse signal incident on the detection cable 11 is generated, and the reflected wave from the detection cable 11 is amplified and A / D converted.
  • step 102 the CPU 21 causes the leakage detection pulse signal generated based on the pulse signal to enter the detection cable.
  • step 103 the CPU 21 amplifies the reflected wave at a predetermined sampling signal period, and in step 104, converts the amplified reflected wave from an analog signal to a digital signal.
  • step 105 the CPU 21 stores the data converted into the digital signal.
  • step 106 the CPU 21 determines whether or not steps 102 to 105 have been executed a predetermined number of times. If these steps have not been executed a predetermined number of times, the CPU 21 again enters the leak detection pulse signal into the detection cable in step 102. If these steps have been executed a predetermined number of times, in step 107, the CPU 21 compares the processing data that has undergone further processing such as averaging with the given reference data, and enters the liquid transport pipeline. It is determined whether or not liquid leakage has occurred.
  • FIG. 6 shows another example of the leak detection apparatus according to the present invention.
  • the leak detection device 3 includes a detection sensor 11 and a signal processing unit 4.
  • the signal processing unit 4 included in the leakage detection device 3 is different from the signal processing unit 2 included in the leakage detection device 1 in that it includes a delay amount selection unit 81. Therefore, here, the matters relating to the delay amount selection unit 81 which is the difference will be mainly described, and the explanation relating to the matters overlapping with the matters described above will be omitted.
  • the delay amount selection unit 81 receives the pulse signal generated by the pulse generation unit 31 and also receives the selection signal from the CPU 21 and is delayed by the delay amount selected by the selection signal. Is provided to the CPU 21 and the ADC 61 as a sampling signal. That is, the delay amount selection unit 81 can execute processing in the gain amplifier 53 and the ADC 61 at a timing delayed by the selected delay amount with respect to the pulse signal generated by the pulse generation unit 31. is there. As a result, leak detection can be performed with higher resolution than the leak detection device 1 that does not include the delay amount selection unit 81. That is, it is possible to shorten the measurement distance interval of the detection cable 11 and improve the resolution by sampling the time between the periods of the leakage detection pulse signal with the sampling signal delayed by the delay amount selection unit 81. is there.
  • the operation of the leakage detection device 3 having the delay amount selection unit 81 is performed by using the detection cable 11 having the porous PTFE having the relative dielectric constant ⁇ of 1.5 described above and the pulse signal generated by the pulse signal generation unit 31.
  • the frequency is 31.25 [MHz] will be described as an example.
  • the period of the pulse signal is 32 [ns], which corresponds to 4 [m] when converted to the sampling distance interval of the detection cable 11.
  • the delay amount selection unit 81 controls a pulse signal obtained by delaying the pulse signal generated by the pulse generation unit 31 through delay elements 83a, 83b, 83g, and the like by the selection signal.
  • the data is selected by the selector 85 and provided to the ADC 61 and the CPU 21.
  • the selector 85 shown in FIG. 7 outputs the pulse signal input to Din0 to Dout, the sampling points of the pulse signal are 0 [m], 4 [m] in order. ], 8 [m],. . . , 992 [m], 996 [m], 1000 [m],. . . Is assumed to correspond.
  • sampling points are 0.5 [m], 4.5 [m], 8.5 [m],. . . 992.5 [m], 996.5 [m], 1000.5 [m],. . .
  • 4 [ns] which is the delay difference between both pulse signals, corresponds to 0.5 [m] in the distance interval of the detection cable 11.
  • sampling points are 1 [m], 5 [m], and 9 [m]. ],. . . , 993 [m], 997 [m], 1001 [m],. . .
  • the resolution of the detection cable 11 can be increased without increasing the frequency of the pulse signal generated by the pulse generator 31. it can.
  • the sampling frequency is increased, it is necessary to use a signal processing circuit and a CPU having a high data rate.
  • the price of electronic components such as the ADC 51 and the DAC 61 increases exponentially as the rated sampling frequency increases.
  • the electronic circuit board In order to cope with high-frequency operation, the electronic circuit board must also use an expensive board with high noise resistance.
  • the leak detection device 3 having the delay amount selection unit 81 a plurality of signals obtained by delaying the pulse signal by different delay amounts are used as sampling signals without increasing the frequency of the pulse signal generated by the pulse generation unit 31. , Can increase the resolution. For example, even when a general-purpose pulse generation unit that generates a frequency such as 31.25 [MHz] is used, data with sufficiently high resolution and reliability can be acquired in a short time.
  • step 201 the CPU 21 provides a selection signal to the delay amount selection unit 81.
  • Steps 202 to 207 are the same as steps 101 to 106 in FIG.
  • step 208 after the leakage detection pulse is incident on the detection cable 11 for a predetermined number of times and the reflected signal is stored, the CPU 21 determines whether or not there is a delay amount not selected by the delay amount selection unit 81. To do. If there is an unselected delay amount, the process returns to step 201. If all the delay amounts are selected, in step 209, the CPU 21 combines the processing data delayed by different delay amounts into one data. By combining the processing data, processing data with improved resolution can be obtained. In step 210, the processed data is compared with the reference data.
  • the present invention can be used not only to identify a leak location in a transport pipeline, but also to identify a fault location in a leak detection cable.
  • a leakage detection apparatus that uses a coaxial cable having porous PTFE having a relative dielectric constant ⁇ of 1.5 as a detection cable has been described.
  • a detection cable having porous PTFE having a different dielectric constant or a detection cable using another resin as an insulating material can also be used as the detection cable.
  • the leak detection pulse signal is generated by the signal of the pulse generation unit 31 that generates the sampling signal, but can also be generated by another pulse generator.

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Abstract

The purpose of the present invention is to provide a leak detection device which achieves a reduction in processing time. This leak detection device comprises a leak detection cable (11) which is laid along a pipeline and has a characteristic impedance that is changed by infiltration of liquid leaking from the pipeline, a leak detection pulse signal generation unit (33) which generates a leak detection pulse signal incident on the leak detection cable, a storage unit (23) which stores data indicating the correlation between the propagation distance of a reflected wave and the attenuation of the reflected wave, an amplification factor variable gain amplifier (53) which is a gain amplifier for amplifying the reflected wave of the leak detection pulse signal in synchronization with a sampling signal repeated with a predetermined sampling period, and changes the amplification factor of the reflected wave on the basis of data; and an A/D conversion unit (61) which samples the amplified reflected wave of one leak detection pulse signal in synchronization with the sampling signal multiple times and converts the sampled reflected wave into a digital signal.

Description

液体輸送パイプラインの漏洩検出装置、及びその方法Leakage detection apparatus and method for liquid transportation pipeline
　本発明は、石油パイプラインなどの液体輸送パイプラインの漏洩検出装置に関する。具体的には、検出ケーブルに入射されるパルス信号の反射波を検出することにより、同軸ケーブルなどの検出ケーブルの線路の特性インピーダンスの変化を検出し、検出ケーブルの欠陥箇所、及び液体輸送パイプラインの漏洩箇所などを、短時間に特定する漏洩検出装置に関する。 The present invention relates to a leak detection device for a liquid transportation pipeline such as an oil pipeline. Specifically, a change in characteristic impedance of a detection cable line such as a coaxial cable is detected by detecting a reflected wave of a pulse signal incident on the detection cable, and a defective portion of the detection cable and a liquid transport pipeline are detected. The present invention relates to a leak detection device that identifies a leak location of a short time.
　同軸ケーブルの特性インピーダンスを計測する方法の１つとして、ＴＤＲ法（Ｔｉｍｅ　Ｄｏｍａｉｎ　Ｒｅｆｌｅｃｔｏｍｅｔｒｙ、時間領域反射法）が知られる。ＴＤＲ法を応用した検出器として、同軸ケーブルの異常個所を検出する検出器、及び同軸ケーブルを検出ケーブルとして使用する漏洩検出器などがある。例えば、１０ｍ以上、特に１００ｍ~５０００ｍ程度の長さを有する液体輸送パイプライン、貯蔵タンク、及びこれらの附属設備（以下、液体輸送パイプライン等という）からの液体の漏洩を検出するために、ＴＤＲ法を応用した漏洩検出装置が知られる（特許文献１~３参照のこと）。この漏洩検出装置は、同軸ケーブルなどにより構成される検出ケーブルと、検出ケーブルの一端から入射されるパルス信号を生成するパルス信号生成器と、検出ケーブルからのパルス信号の反射波を検出する検出器とを有する。検出ケーブルは、液体輸送パイプライン等の下方に配置され、検出ケーブル内の導体間に配置される絶縁体には、検出対象の液体が浸潤、又は浸透すると、特性インピーダンスが変化する材料が採用される。また、検出ケーブルの他端は、検出ケーブルの特性インピーダンスと等価のインピーダンスを有する終端器が接続されて、特性インピーダンスと整合がとられる。このため、漏洩がない場合には、検出ケーブルに入射されるパルス信号は、反射波を生じない。しかしながら、液体輸送パイプライン等から液体が漏洩すると、検出ケーブルは、パイプラインから漏洩した液体が浸透して、浸透した部分の特性インピーダンスが変化する。この結果、検出ケーブルにパルス信号が入射されると、液体の浸潤により特性インピーダンスが変化した部分の前後で反射波を生じる。検出器は、この反射波を検出することにより、漏洩を検出する。 A TDR method (Time Domain Reflectometry, time domain reflection method) is known as one of methods for measuring the characteristic impedance of a coaxial cable. As detectors to which the TDR method is applied, there are a detector that detects an abnormal portion of a coaxial cable, a leak detector that uses the coaxial cable as a detection cable, and the like. For example, in order to detect leakage of liquid from a liquid transport pipeline having a length of 10 m or more, in particular, about 100 m to 5000 m, and a storage tank and their associated equipment (hereinafter referred to as a liquid transport pipeline, etc.) There is known a leak detection device applying the method (see Patent Documents 1 to 3). This leakage detection device includes a detection cable configured by a coaxial cable, a pulse signal generator that generates a pulse signal incident from one end of the detection cable, and a detector that detects a reflected wave of the pulse signal from the detection cable And have. The detection cable is arranged below the liquid transport pipeline, etc., and the insulator that is arranged between the conductors in the detection cable is made of a material whose characteristic impedance changes when the liquid to be detected infiltrates or penetrates. The Further, a terminator having an impedance equivalent to the characteristic impedance of the detection cable is connected to the other end of the detection cable so as to be matched with the characteristic impedance. For this reason, when there is no leakage, the pulse signal incident on the detection cable does not generate a reflected wave. However, when the liquid leaks from the liquid transport pipeline or the like, the liquid leaking from the pipeline penetrates the detection cable, and the characteristic impedance of the penetrated portion changes. As a result, when a pulse signal is incident on the detection cable, a reflected wave is generated before and after the portion where the characteristic impedance has changed due to liquid infiltration. The detector detects leakage by detecting this reflected wave.
　また、このような漏洩検出装置を使用して、漏洩を検出するとともに、漏洩箇所を特定することができる。例えば、特許文献４に開示されるように、パルス信号を検出ケーブルに入射してから反射波が検出されるまでの時間の計測値と、検出ケーブルのパルス信号伝搬時間とから漏洩箇所を算出することができる。 In addition, using such a leak detection device, it is possible to detect a leak and identify the leak location. For example, as disclosed in Patent Document 4, the leak location is calculated from the measured value of the time from when the pulse signal is incident on the detection cable until the reflected wave is detected and the pulse signal propagation time of the detection cable. be able to.
　従来のＴＤＲ法を応用した漏洩検出装置では、パルス信号を入射するごとに、１つの地点の反射波を計測することによって、それぞれの計測地点の特性インピーダンスを把握する方式が採用される。これは、反射波の減衰が、計測地点と検出地点との間の伝搬距離に依存するため、計測地点ごとに、反射波の増幅率が異なるためである。 A conventional leak detection apparatus using the TDR method employs a method of measuring the reflected wave at one point each time a pulse signal is incident, thereby grasping the characteristic impedance at each measurement point. This is because the attenuation of the reflected wave depends on the propagation distance between the measurement point and the detection point, and the amplification factor of the reflected wave is different for each measurement point.
特開昭５４−６８６９０号公報JP 54-68690 A 特開昭５６−２２９２３号公報JP 56-22923 A 特開昭５７−１１４８３２号公報Japanese Patent Application Laid-Open No. 57-114832 特開昭５８−３３１４５号公報JP 58-33145 A
　しかしながら、従来の漏洩検出装置では、計測するパイプラインの長さが増加するほど、また計測地点の間の間隔を狭くして計測値の分解能を高くするほど、計測回数が増加するために、計測回数に比例して処理時間が長くなるという不具合があった。 However, in the conventional leak detection device, the number of measurements increases as the length of the pipeline to be measured increases, and as the interval between the measurement points is narrowed to increase the resolution of the measurement value. There was a problem that the processing time was increased in proportion to the number of times.
　そこで、本発明は、上述した不具合を解決することが可能な漏洩検出装置を提供することを目的とする。 Therefore, an object of the present invention is to provide a leak detection device capable of solving the above-described problems.
　また、本発明は、反射波の伝搬距離と、反射波の減衰との相関を表すデータに基づいて、特定のサンプリング周期で反射波を増幅する増幅部を採用することにより、処理時間を短縮する漏洩検出装置を提供することを目的とする。 Further, the present invention shortens the processing time by employing an amplification unit that amplifies the reflected wave at a specific sampling period based on data representing the correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave. An object is to provide a leak detection device.
　上記目的を実現するため、本発明の漏洩検出装置は、漏洩検出ケーブルに入射される漏洩検出パルス信号の反射波を検出することによって、液体輸送パイプラインからの液体漏洩を検出する装置であって、パイプラインに沿って敷設され、パイプラインから漏洩した液体が浸透することにより特性インピーダンスが変化する漏洩検出ケーブルと、漏洩検出ケーブルに入射される漏洩検出パルス信号を生成する漏洩検出パルス信号生成部と、反射波の伝播距離と、反射波の減衰との相関を表すデータを記憶する記憶部と、所定のサンプリング周期で繰り返されるサンプリング信号に同期して、漏洩検出パルス信号に対する反射波を増幅するゲインアンプであって、データに基づいて、反射波の増幅率を変更する増幅率可変ゲインアンプと、サンプリング信号に同期して、１つの漏洩検出パルス信号に対する増幅された反射波を複数回サンプリングし、サンプリングした反射波をデジタル信号に変換するＡ／Ｄ変換部と、を有することを特徴とする。 In order to achieve the above object, a leak detection device of the present invention is a device that detects a liquid leak from a liquid transport pipeline by detecting a reflected wave of a leak detection pulse signal incident on a leak detection cable. A leak detection cable that is laid along the pipeline and changes its characteristic impedance when liquid leaked from the pipeline permeates, and a leak detection pulse signal generator that generates a leak detection pulse signal incident on the leak detection cable And a storage unit for storing data representing the correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave, and the reflected wave with respect to the leak detection pulse signal is amplified in synchronization with the sampling signal repeated at a predetermined sampling period. A gain amplifier that changes the gain of the reflected wave based on the data, and a gain amplifier; In synchronization with the pulling signal, a reflected wave is amplified for one leak detection pulse signal sampled a plurality of times, and having an A / D converter for converting the reflected wave sampled digital signal.
　本発明によれば、所定のサンプリング周期ごとに、反射波の伝播距離と、反射波の減衰との相関を表すデータに基づいて、反射波を増幅するゲインアンプを有するので、液体輸送パイプラインの液体漏洩の有無を短時間で検出できる漏洩検出装置を実現できる。 According to the present invention, since it has the gain amplifier that amplifies the reflected wave based on the data representing the correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave for each predetermined sampling period, the liquid transport pipeline A leak detection device that can detect the presence or absence of liquid leak in a short time can be realized.
本発明に係る漏洩検出装置の一例を示す図である。It is a figure which shows an example of the leak detection apparatus which concerns on this invention. 本発明に係る漏洩検出装置で採用される検出ケーブルの一例を示す図である。It is a figure which shows an example of the detection cable employ | adopted with the leak detection apparatus which concerns on this invention. 本発明に係る漏洩検出装置で採用されるゲインアンプの回路構成の一例を示す図である。It is a figure which shows an example of the circuit structure of the gain amplifier employ | adopted with the leak detection apparatus which concerns on this invention. 本発明に係るタイミングチャートの一例を示す図である。It is a figure which shows an example of the timing chart which concerns on this invention. 本発明に係る漏洩検出方法の一例を示す図である。It is a figure which shows an example of the leak detection method which concerns on this invention. 本発明に係る漏洩検出装置の他の例を示す図である。It is a figure which shows the other example of the leak detection apparatus which concerns on this invention. 本発明に係る漏洩検出装置で採用される遅延量選択部の回路構成の一例を示す図である。It is a figure which shows an example of the circuit structure of the delay amount selection part employ | adopted with the leak detection apparatus which concerns on this invention. 本発明に係るタイミングチャートの他の例を示す図である。It is a figure which shows the other example of the timing chart which concerns on this invention. 本発明に係る漏洩検出方法の他の例を示す図である。It is a figure which shows the other example of the leak detection method which concerns on this invention.
　以下、添付図面を参照して、本発明に係る漏洩検出装置について詳細に説明する。それぞれの図面において、同一、又は類似する機能を有する構成素子には、同一、又は類似する符号が付される。したがって、先に説明した構成要素と同一、又は類似する機能を有する構成素子に関しては、改めて説明をしないことがある。 Hereinafter, a leak detection apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In each drawing, components having the same or similar functions are denoted by the same or similar reference numerals. Therefore, a component having the same or similar function as the component described above may not be described again.
　図１において、本発明に係る漏洩検出装置の一例を示す。図１に示すように、漏洩検出装置１は、検出センサ１１と、信号処理部２とを有する。検出センサ１１は、石油などの液体を輸送する液体輸送パイプライン１００の下部に配置されて、液体輸送パイプライン１００から液体が漏洩した場合には、漏洩した液体が検出センサ１１に浸透する。信号処理部２は、検出センサ１１にパルス信号を入射し、漏洩した液体が検出センサ１１に浸透した場合に生じる反射波を処理し、液体輸送パイプライン１００の漏洩を検出し、かつ漏洩箇所を特定する。 FIG. 1 shows an example of a leak detection apparatus according to the present invention. As shown in FIG. 1, the leak detection device 1 includes a detection sensor 11 and a signal processing unit 2. The detection sensor 11 is disposed below the liquid transport pipeline 100 that transports a liquid such as petroleum. When the liquid leaks from the liquid transport pipeline 100, the leaked liquid penetrates the detection sensor 11. The signal processing unit 2 inputs a pulse signal to the detection sensor 11, processes a reflected wave generated when the leaked liquid penetrates the detection sensor 11, detects a leak in the liquid transport pipeline 100, and detects the leak location Identify.
　図２において、本発明に係る漏洩検出装置１で採用される検出ケーブル１１の一例を示す。図２に示すように、検出ケーブル１１は、内部導体１１ａと、外部導体１１ｂとを有する。内部導体１１ａは、裸軟銅などで形成でき、外部導体１１ｂは、錫めっき軟銅線を編組、あるいは錫めっき軟銅線、及び多孔質ＰＴＦＥ（ｐｏｌｙｔｅｔｒａｆｌｕｏｒｏｅｔｈｙｌｅｎｅ、ポリテトラフルオロエチレン）テープを混合して編組するなどして形成できる。図１に示されるように、内部導体１１ａの一端は、信号処理部２に接続され、他端は、好適には終端器１３に接続される。終端器１３のインピーダンスは、検出ケーブル１１の特性インピーダンスと等価にすることができる。これにより、検出ケーブルの一端からパルス信号を入射したときに、反射波を生じさせないようにできる。また、外部導体１１ｂは、大地に接地される。 FIG. 2 shows an example of the detection cable 11 employed in the leak detection apparatus 1 according to the present invention. As shown in FIG. 2, the detection cable 11 includes an inner conductor 11a and an outer conductor 11b. The inner conductor 11a can be formed of bare annealed copper or the like, and the outer conductor 11b is braided by tin-plated annealed copper wire, or braided by mixing tin-plated annealed copper wire and porous PTFE (polytetrafluoroethylene). Can be formed. As shown in FIG. 1, one end of the internal conductor 11 a is connected to the signal processing unit 2, and the other end is preferably connected to the terminator 13. The impedance of the terminator 13 can be equivalent to the characteristic impedance of the detection cable 11. Accordingly, it is possible to prevent a reflected wave from being generated when a pulse signal is incident from one end of the detection cable. The outer conductor 11b is grounded to the ground.
　再び図２を参照すると、検出ケーブル１１の内部導体１１ａと、外部導体１１ｂとの間には、内部保護層１１ｃと、検出層１１ｄとが配置される。また、外部導体１１ｂの外周には、外部保護層１１ｅと、保護編組１１ｆとが配置される。外部導体１１ｂの外周に配置される外部保護層１１ｅと、検出層１１ｄは、多孔質ＰＴＦＥのテープで形成される。当業者に知られるように、多孔質ＰＴＦＥは、良好な撥水性を有する一方、油類を容易に浸透させる特性を有する。このため、多孔質ＰＴＦＥのテープを材料として含む外部保護層１１ｅ、外部導体１１ｂ、及び検出層１１ｄは、雨水などの水分を浸透させずに、油類を透過させることが可能である。さらにＰＴＦＥは、油類を含有することにより比誘電率が変化する特性を有する。このため、内部導体１１ａと、外部導体１１ｂとの間に形成される検出層１１ｄは、油類が浸透した場合に検出ケーブル１１の特性インピーダンスが変化する。検出層１１ｄなどの材料に採用される多孔質ＰＴＦＥテープは、多孔質中の空気の含有率が異なる種々の多孔質ＰＴＦＥテープにできる。多孔質中の空気の含有率を変化させることで、所望の誘電率を有する多孔質ＰＴＦＥのテープを形成できる。なお、内部保護層１１ｃは、ＰＦＡ（パーフルオロアルコキシアルカン）などの樹脂で形成され、内部導体１１ａに油類が浸透することを防止できる。 Referring to FIG. 2 again, an inner protective layer 11c and a detection layer 11d are disposed between the inner conductor 11a and the outer conductor 11b of the detection cable 11. An outer protective layer 11e and a protective braid 11f are disposed on the outer periphery of the outer conductor 11b. The outer protective layer 11e and the detection layer 11d disposed on the outer periphery of the outer conductor 11b are formed of porous PTFE tape. As known to those skilled in the art, porous PTFE has good water repellency, while having the property of easily penetrating oils. For this reason, the external protective layer 11e, the external conductor 11b, and the detection layer 11d including a porous PTFE tape as a material can transmit oil without allowing moisture such as rainwater to permeate. Furthermore, PTFE has the characteristic that the dielectric constant changes by containing oils. For this reason, the characteristic impedance of the detection cable 11 changes in the detection layer 11d formed between the inner conductor 11a and the outer conductor 11b when oil penetrates. The porous PTFE tape employed for the material such as the detection layer 11d can be various porous PTFE tapes having different air contents in the porous material. By changing the air content in the porous material, a porous PTFE tape having a desired dielectric constant can be formed. The inner protective layer 11c is formed of a resin such as PFA (perfluoroalkoxyalkane) and can prevent oils from penetrating into the inner conductor 11a.
　検出ケーブル１１と、信号処理部２とは、直接接続することも可能であるが、好適には、検出ケーブル１１と、信号処理部２との間にダミーケーブル１５を挿入することができる。ダミーケーブル１５を挿入しない場合、入射されるパルス信号と、反射波とが重畳して、反射波を検出できない可能性があるためである。ダミーケーブルの長さは、入力される漏洩検出パルスのパルス幅などによって、決定される。例えば、ダミーケーブルの長さは、１００〔ｍ〕にできる。また、液体輸送パイプライン１００と、検出ケーブル１１との間にセーフティバリア１１０を配置することができる。セーフティバリア１１０は、検出ケーブル１１の発熱などにより、液体輸送パイプライン１００から漏洩した石油などの可燃性の液体が発火することを防止する機能を有する。 The detection cable 11 and the signal processing unit 2 can be directly connected, but preferably, a dummy cable 15 can be inserted between the detection cable 11 and the signal processing unit 2. This is because when the dummy cable 15 is not inserted, there is a possibility that the incident pulse signal and the reflected wave are superimposed and the reflected wave cannot be detected. The length of the dummy cable is determined by the pulse width of the input leakage detection pulse. For example, the length of the dummy cable can be set to 100 [m]. In addition, a safety barrier 110 can be disposed between the liquid transport pipeline 100 and the detection cable 11. The safety barrier 110 has a function of preventing a combustible liquid such as petroleum leaking from the liquid transport pipeline 100 from igniting due to heat generated by the detection cable 11 or the like.
　再び図１を参照して、漏洩検出装置１の信号処理部２について説明する。信号処理部２は、中央演算処理装置（ＣＰＵ）２１と、記憶部２３と、パルス生成部３１と、パルス幅制御部３３と、Ｉ／Ｏ部４１と、デジタル‐アナログ変換部（ＤＡＣ）５１と、ゲインアンプ５３と、アナログ‐デジタル変換部（ＡＤＣ）６１と、データＩ／Ｏ部７１とを有する。ＣＰＵ２１は、記憶部２３、パルス生成部３１、及びパルス幅制御部３３などと接続され、それぞれの素子を制御する。パルス生成部３１は、ＣＰＵ２１の制御に基づき、パルス信号を生成して、検出ケーブル１１に入射する信号を生成するパルス幅制御部３３に提供するとともに、反射波を増幅するゲインアンプ５３を制御するＣＰＵ２１と、反射波をデジタルデータに変換するＡＤＣ６１とにサンプリング信号として提供する。パルス幅制御部３３は、分周回路などによって、パルス生成部３１が発生したパルス信号の周期、及びパルス幅を変更して、検出ケーブル１１に入力するのに適当な漏洩検出パルス信号を生成する。例えば、検出ケーブルが、１０００〔ｍ〕程度の長さを有する場合は、漏洩検出パルス信号は、２００〔ｎｓ〕~２５０〔ｎｓ〕程度のパルス幅を有していればよい。パルス幅制御部３３で生成された漏洩検出パルス信号は、Ｉ／Ｏ部４１を介して検出ケーブル１１に送信される。検出ケーブル１１に入射される漏洩検出パルス信号は、液体輸送パイプライン１００に漏洩がなく、検出ケーブル１１の特性インピーダンスに線路方向での不整合がない場合には、終端器１３に吸収されて、反射波は発生しない。 Referring to FIG. 1 again, the signal processing unit 2 of the leak detection apparatus 1 will be described. The signal processing unit 2 includes a central processing unit (CPU) 21, a storage unit 23, a pulse generation unit 31, a pulse width control unit 33, an I / O unit 41, and a digital-analog conversion unit (DAC) 51. A gain amplifier 53, an analog-digital converter (ADC) 61, and a data I / O unit 71. The CPU 21 is connected to the storage unit 23, the pulse generation unit 31, the pulse width control unit 33, and the like, and controls each element. The pulse generation unit 31 generates a pulse signal based on the control of the CPU 21, provides the pulse signal to the pulse width control unit 33 that generates a signal incident on the detection cable 11, and controls the gain amplifier 53 that amplifies the reflected wave. This is provided as a sampling signal to the CPU 21 and the ADC 61 that converts the reflected wave into digital data. The pulse width control unit 33 changes the cycle of the pulse signal generated by the pulse generation unit 31 and the pulse width by a frequency divider circuit or the like, and generates a leak detection pulse signal suitable for input to the detection cable 11. . For example, when the detection cable has a length of about 1000 [m], the leakage detection pulse signal may have a pulse width of about 200 [ns] to 250 [ns]. The leak detection pulse signal generated by the pulse width control unit 33 is transmitted to the detection cable 11 via the I / O unit 41. The leakage detection pulse signal incident on the detection cable 11 is absorbed by the terminator 13 when there is no leakage in the liquid transport pipeline 100 and the characteristic impedance of the detection cable 11 does not match in the line direction. No reflected wave is generated.
　一方、液体輸送パイプライン１００に液体漏洩が発生し、検出ケーブル１１の特性インピーダンスに線路方向での不整合が生じる場合には、反射波は、発生する。検出ケーブル１１内で発生した反射波は、バッファ、及びアッテネータを有するＩ／Ｏ部４１を介して、ゲインアンプ５３に送信される。後に詳細に説明されるように、ゲインアンプ５３は、パルス生成部３１が生成するサンプリング信号のサンプリング周期ごとに、ＤＡＣ５１を介して読み出される記憶部２３に記憶されるゲインテーブルに基づいて、漏洩地点に応じた適当な大きさに反射波を増幅する。ゲインアンプ５３で増幅された反射波は、ＡＤＣ６１によって、パルス生成部３１が生成するサンプリング信号のサンプリング周期でサンプリングされ、デジタル信号に変換される。ＡＤＣ６１でデジタル化された信号は、記憶部２３に記憶されるとともに、データＩ／Ｏ部７１を介して、データ処理部２の外部に配置される表示装置１１３、及び記憶装置に提供される。 On the other hand, when liquid leakage occurs in the liquid transport pipeline 100 and the characteristic impedance of the detection cable 11 is mismatched in the line direction, a reflected wave is generated. The reflected wave generated in the detection cable 11 is transmitted to the gain amplifier 53 via the I / O unit 41 having a buffer and an attenuator. As will be described in detail later, the gain amplifier 53 detects the leakage point based on the gain table stored in the storage unit 23 that is read out via the DAC 51 for each sampling period of the sampling signal generated by the pulse generation unit 31. The reflected wave is amplified to an appropriate size according to the above. The reflected wave amplified by the gain amplifier 53 is sampled by the ADC 61 at the sampling period of the sampling signal generated by the pulse generator 31 and converted into a digital signal. The signal digitized by the ADC 61 is stored in the storage unit 23 and also provided to the display device 113 and the storage device arranged outside the data processing unit 2 via the data I / O unit 71.
　ここで、パルス生成部３１が生成するパルス信号の周波数と、検出ケーブル１１の入射端、及び計測地点の間の距離との相関について説明する。まず、検出ケーブル１１中を漏洩検出パルス信号、及び反射波が１ｍ移動する時間ｔｃ〔ｓ／ｍ〕を算出する。マックスウェルの方程式から導き出されるように物質中の電磁的な信号の伝搬速度Ｖｃは、
Figure JPOXMLDOC01-appb-I000001
　で示される。ここで、ｃは、真空中の光速２．９９×１０８〔ｍ／ｓ〕であり、μは、比透磁率であり、εは、比誘電率である。また、検出ケーブル１１を漏洩検出パルス信号、及び反射波が１ｍ移動する時間ｔｃは、信号の伝搬速度Ｖｃの逆数で表すことができるので、ｔｃは、
Figure JPOXMLDOC01-appb-I000002
　で示される。ここで、比透磁率μを、１と仮定し、検出ケーブル１１の検出層に使用される多孔質ＰＴＦＥの比誘電率εを、１．５と仮定すると、検出ケーブル１１中を漏洩検出パルス信号、及び反射波が１ｍ移動する時間ｔｃは、
Figure JPOXMLDOC01-appb-I000003
　となる。さらに、検出ケーブル１１の入射端から漏洩検出パルス信号が入射し、Ｌ〔ｍ〕離れた地点で反射した反射波が戻ってくるまでの時間Δｔ〔ｎｓ〕は、
　Δｔ　＝　２×Ｌ×ｔｃ　≒　８Ｌ〔ｎｓ〕
　となる。一方、パルス生成部３１が生成するパルス信号の周波数が例えば、３１．２５〔ＭＨｚ〕であると仮定すると、パルス信号の周期Ｔは、
　Ｔ　＝　１／３１．２５×１０６　＝　３２×１０−９〔ｓ〕
　　　＝　３２〔ｎｓ〕
　となる。これから、比誘電率εが１．５である多孔質ＰＴＦＥを有する検出ケーブルを使用した場合に、このパルス信号を使用して、３１．２５〔ＭＨｚ〕のサンプリング周波数で反射波をサンプリングすることは、
　Ｌ　＝　３２／８　＝　４〔ｍ〕
　ごとの検出ケーブル１１の反射波を検出することに相当する。このように、パルス生成部３１が生成する特定のサンプリング周波数で反射波をサンプリングすることは、検出ケーブル１１を特定の距離間隔でサンプリングすることに相当する。 Here, the correlation between the frequency of the pulse signal generated by the pulse generator 31 and the distance between the incident end of the detection cable 11 and the measurement point will be described. First, the leakage detection pulse signal and the time tc [s / m] for which the reflected wave moves by 1 m in the detection cable 11 are calculated. As derived from Maxwell's equations, the propagation speed Vc of the electromagnetic signal in the material is
Figure JPOXMLDOC01-appb-I000001
Indicated by Here, c is the speed of light in vacuum of 2.99 × 10 8 [m / s], μ is relative permeability, and ε is relative permittivity. Further, since the leak detection pulse signal and the time tc during which the reflected wave moves 1 m through the detection cable 11 can be expressed by the reciprocal of the signal propagation velocity Vc, tc is
Figure JPOXMLDOC01-appb-I000002
Indicated by Here, assuming that the relative permeability μ is 1, and assuming that the relative dielectric constant ε of the porous PTFE used for the detection layer of the detection cable 11 is 1.5, the leakage detection pulse signal is passed through the detection cable 11. , And the time tc when the reflected wave travels 1 m is
Figure JPOXMLDOC01-appb-I000003
It becomes. Furthermore, the time Δt [ns] from when the leakage detection pulse signal is incident from the incident end of the detection cable 11 until the reflected wave reflected at a point away from L [m] returns.
Δt = 2 × L × tc≈8L [ns]
It becomes. On the other hand, assuming that the frequency of the pulse signal generated by the pulse generator 31 is, for example, 31.25 [MHz], the period T of the pulse signal is
T = 1 / 31.25 × 10 6 = 32 × 10 −9 [s]
= 32 [ns]
It becomes. From this, when using a detection cable having porous PTFE having a relative dielectric constant ε of 1.5, it is possible to sample a reflected wave at a sampling frequency of 31.25 [MHz] using this pulse signal. ,
L = 32/8 = 4 [m]
This corresponds to detecting the reflected wave of each detection cable 11. As described above, sampling the reflected wave at the specific sampling frequency generated by the pulse generation unit 31 corresponds to sampling the detection cable 11 at a specific distance interval.
　以下の説明では、パルス生成部３１が生成するパルス周波数を３１．２５〔ＭＨｚ〕とし、検出ケーブル１１の比誘電率εが１．５である多孔質ＰＴＦＥを有すると仮定される。すなわち、パルス生成部３１が生成するサンプリング周波数は、検出ケーブル１１を４〔ｍ〕ごとにサンプリングすることに相当すると仮定される。しかしながら、本発明に係る漏洩検出装置、及びその方法を使用する場合は、他のパルス周波数、及び比誘電率εを有する検出ケーブル１１を使用しても、本発明の範囲に包含されることは、当業者には当然に理解されるであろう。 In the following description, it is assumed that the pulse frequency generated by the pulse generator 31 is 31.25 [MHz] and the detection cable 11 has porous PTFE having a relative dielectric constant ε of 1.5. That is, it is assumed that the sampling frequency generated by the pulse generator 31 corresponds to sampling the detection cable 11 every 4 [m]. However, when using the leakage detection apparatus and method according to the present invention, it is included in the scope of the present invention even if the detection cable 11 having other pulse frequency and relative dielectric constant ε is used. Those skilled in the art will naturally understand.
　次に、図１を再び参照して、ゲインアンプ５３において、反射波を増幅する方法について説明する。ゲインアンプ５３は、記憶部２３に記憶されるゲインテーブルに基づいて、入射端からの距離に応じた適当な増幅率で、反射波を増幅する。記憶部２３に記憶されるゲインテーブルには、漏洩検出パルス信号を入射する端部と計測地点との間の距離、すなわち反射波の伝搬距離と、反射波の減衰との相関を表すデータが記憶される。ＣＰＵ２１は、ゲインテーブルに記憶されるデータを、パルス生成部３１が生成するサンプリング信号の周期で読み出して、ＤＡＣ５１にゲインアンプ５３の制御信号として提供する。この制御信号は、ゲインアンプ５３の増幅率を制御する制御信号に相当するものであり、ゲインアンプ５３が、反射波の伝搬距離に応じて、適当な増幅率で反射波を増幅するための信号である。ゲインテーブルには、ゲインアンプ５３の増幅率を制御する制御信号に相当するデータを記憶することができ、また反射波の伝搬距離ごとの反射波の減衰率などの実測値を記憶することもできる。後者の場合は、記憶部２３は、記憶された実測値と、ゲインアンプ５３の増幅率との相関を示すデータを記憶し、ＣＰＵ２１は、これらのデータに基づいて、適当な増幅率を算出する。好適には、ゲインテーブルに記憶される反射波の減衰率の計測地点の間隔は、サンプリング周期と同期させた距離間隔にすることができる。例えば、パルス生成部３１のパルス信号のサンプリング周期が４〔ｍ〕ごとに相当する場合は、ゲインテーブルの間隔も４〔ｍ〕ごとにできる。なお、物理的な反射波の伝搬距離と、ゲインテーブルに記憶される増幅値に対応する距離との対応は、漏洩検出装置を設置するときに、ダミーケーブルの長さ、漏洩検出装置の設置場所と、検出対象のパイプラインとの間の距離などの設置条件に基づいて決定される。 Next, referring to FIG. 1 again, a method of amplifying the reflected wave in the gain amplifier 53 will be described. Based on the gain table stored in the storage unit 23, the gain amplifier 53 amplifies the reflected wave with an appropriate amplification factor according to the distance from the incident end. The gain table stored in the storage unit 23 stores data indicating the correlation between the distance between the end where the leak detection pulse signal is incident and the measurement point, that is, the propagation distance of the reflected wave and the attenuation of the reflected wave. Is done. The CPU 21 reads the data stored in the gain table at the cycle of the sampling signal generated by the pulse generator 31 and provides it to the DAC 51 as a control signal for the gain amplifier 53. This control signal corresponds to a control signal for controlling the gain of the gain amplifier 53. The gain amplifier 53 amplifies the reflected wave with an appropriate gain according to the propagation distance of the reflected wave. It is. In the gain table, data corresponding to a control signal for controlling the gain of the gain amplifier 53 can be stored, and an actual measurement value such as the attenuation rate of the reflected wave for each propagation distance of the reflected wave can also be stored. . In the latter case, the storage unit 23 stores data indicating the correlation between the stored actual measurement value and the gain of the gain amplifier 53, and the CPU 21 calculates an appropriate gain based on these data. . Preferably, the interval between the measurement points of the reflected wave attenuation rate stored in the gain table can be a distance interval synchronized with the sampling period. For example, when the sampling period of the pulse signal of the pulse generation unit 31 corresponds to every 4 [m], the gain table interval can be set every 4 [m]. Note that the correspondence between the propagation distance of the physical reflected wave and the distance corresponding to the amplification value stored in the gain table depends on the length of the dummy cable and the location of the leak detection device when installing the leak detection device. And the installation conditions such as the distance to the detection target pipeline.
　ゲインアンプ５３は、検出ケーブル１１の断線、又は短絡を検出する断線／短絡検出断線／短絡検出試験モードと、液体輸送パイプラインの液体漏洩を検出する漏洩検出モードの２つのモードを有することができる。断線、又は短絡時に発生する反射波は、漏洩時に発生する反射波よりも振幅が数倍程度大きくなるため、ゲインアンプ５３内部の増幅素子、及びＡＤＣ６１などの電子回路素子を損傷するおそれがあるためである。断線／短絡検出試験モードは、漏洩検出モードを実行する前に実行することができる。図３に、短絡検出試験モード、及び漏洩検出モードの２つのモードを有するゲインアンプ５３の一例を示す。図３に示すように、Ｉ／Ｏ部から入力される反射波は、バッファ５４を介して、マルチプレクサ５６に直接提供される信号と、増幅素子５５をさらに介してマルチプレクサ５６に提供される信号とに分配される。マルチプレクサ５６は、断線／短絡検出試験モードでは、前者を増幅素子５７に提供し、漏洩検出モードでは、後者を増幅素子５７に提供する。増幅素子５７は、ＤＡＣ５１を介して記憶部２３に記憶されたゲインテーブルから生成される制御信号に基づき、反射波を増幅する。増幅素子５７で増幅された反射波は、バッファ５８を介してＡＤＣ６１に提供される。 The gain amplifier 53 can have two modes: a disconnection of the detection cable 11 or a disconnection / short-circuit detection disconnection / short-circuit detection test mode for detecting a short circuit, and a leak detection mode for detecting a liquid leak in the liquid transport pipeline. . Since the reflected wave generated at the time of disconnection or short circuit has an amplitude several times larger than the reflected wave generated at the time of leakage, there is a possibility of damaging the amplification element inside the gain amplifier 53 and an electronic circuit element such as the ADC 61. It is. The disconnection / short circuit detection test mode can be executed before the leakage detection mode is executed. FIG. 3 shows an example of the gain amplifier 53 having two modes of a short circuit detection test mode and a leak detection mode. As shown in FIG. 3, the reflected wave input from the I / O unit includes a signal provided directly to the multiplexer 56 via the buffer 54, and a signal provided to the multiplexer 56 via the amplification element 55. Distributed to. The multiplexer 56 provides the former to the amplification element 57 in the disconnection / short-circuit detection test mode, and provides the latter to the amplification element 57 in the leakage detection mode. The amplifying element 57 amplifies the reflected wave based on a control signal generated from the gain table stored in the storage unit 23 via the DAC 51. The reflected wave amplified by the amplifying element 57 is provided to the ADC 61 via the buffer 58.
　次いで、反射波は、ＡＤＣ６１において、パルス生成部３１が生成したサンプリング信号の周期でサンプリングされて、デジタル変換される。ＡＤＣ６１におけるデジタル変換と、ゲインアンプ５３における増幅とは、いずれもパルス生成部３１が生成したサンプリング信号のサンプリング周期で実行されるため、双方の処理は同期して実行されることになる。また、ＡＤＣ６１は、ＡＤＣ入力遮断信号が入力される場合に、振幅が大きな信号などＡＤＣ６１に不要な信号の入力を阻止できる機能を有することができる。このような機能を有することで、ＡＤＣ６１は、断線、又は短絡時に発生する反射波など振幅の大きな信号が入力されることを回避することができる。 Next, the reflected wave is sampled in the ADC 61 at the sampling signal cycle generated by the pulse generator 31 and converted into a digital signal. Since both the digital conversion in the ADC 61 and the amplification in the gain amplifier 53 are executed in the sampling cycle of the sampling signal generated by the pulse generation unit 31, both processes are executed in synchronization. Further, the ADC 61 can have a function capable of preventing an input of an unnecessary signal to the ADC 61 such as a signal having a large amplitude when an ADC input cutoff signal is input. By having such a function, the ADC 61 can avoid a signal having a large amplitude such as a reflected wave generated at the time of disconnection or short circuit.
　図４を参照して、サンプリング信号、漏洩検出パルス信号、及びＡＤＣ入力遮断信号のタイミングについて説明する。図４は、本実施形態におけるタイミングチャートの一例を示す図である。サンプリング信号は、図１に示すパルス生成部３１で生成されるパルス信号である。サンプリング信号の周期は、検出ケーブル１１の検出層の誘電率ε、及び計測地点間の距離などに依存する。例えば、検出ケーブル１１の検出層の比誘電率εが１．５であり、計測地点間の距離が４〔ｍ〕である場合は、サンプリング信号の周期は、３２〔ｎｓ〕にできる。サンプリング信号に付記される０〔ｍ〕~３２〔ｍ〕の距離は、反射波の伝搬距離である。０〔ｍ〕地点は、挿入されるダミーケーブルの長さ、漏洩検出装置の設置場所と、検出対象のパイプラインとの間の距離などの設置条件に基づいて決定される。漏洩検出パルス信号は、図１に示すパルス幅制御部３３で、パルス生成部３１で生成されたサンプリング信号を分周するなどして形成される。図４に示す例では、漏洩検出パルス信号のパルス幅は、サンプリング信号の８周期分の長さを有する。ＡＤＣ入力遮断信号は、ＡＤＣ６１に振幅が大きい波形など、予期しない波形が入力しないように、ＡＤＣ６１の入力を遮断する信号である。ここでは、ＡＤＣ６１に漏洩検出パルス信号が入力しないように、漏洩検出パルス信号がパルス幅制御部３３から出力される間、及び漏洩検出パルス信号が出力された後の適当な時間の間、出力される。反射波は、ＡＤＣ６１の入力端で観察されるアナログ信号を概略的に示す図である。矢印Ａで示される波形は、保護ダイオードを介して入力させる漏洩検出パルス信号の一部であり、振幅は０．５〔Ｖ〕程度である。矢印Ｂで示される波形は、漏洩検出パルス信号の反射波である。上述のように、検出ケーブル１１の他端は、検出ケーブル１１の特性インピーダンスと等価のインピーダンスを有する終端器１３で終端されるため、反射波は通常、生じない。しかしながら、液体輸送パイプラインなどからの液体漏洩により、検出ケーブル１１の特性インピーダンスが変化した場合には、反射波が生じる。ここでは、１６〔ｍ〕~２４〔ｍ〕の間で液体漏洩が発生した例を示す。 The timing of the sampling signal, leak detection pulse signal, and ADC input cutoff signal will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a timing chart in the present embodiment. The sampling signal is a pulse signal generated by the pulse generator 31 shown in FIG. The period of the sampling signal depends on the dielectric constant ε of the detection layer of the detection cable 11 and the distance between measurement points. For example, when the relative dielectric constant ε of the detection layer of the detection cable 11 is 1.5 and the distance between measurement points is 4 [m], the period of the sampling signal can be 32 [ns]. The distance of 0 [m] to 32 [m] added to the sampling signal is the propagation distance of the reflected wave. The 0 [m] point is determined based on installation conditions such as the length of the dummy cable to be inserted, the installation location of the leak detection device, and the distance between the pipeline to be detected. The leakage detection pulse signal is formed by, for example, dividing the sampling signal generated by the pulse generator 31 by the pulse width controller 33 shown in FIG. In the example shown in FIG. 4, the pulse width of the leak detection pulse signal has a length corresponding to eight cycles of the sampling signal. The ADC input cut-off signal is a signal that cuts off the input of the ADC 61 so that an unexpected waveform such as a waveform having a large amplitude is not input to the ADC 61. Here, the leakage detection pulse signal is output from the pulse width control unit 33 and during an appropriate time after the leakage detection pulse signal is output so that the leakage detection pulse signal is not input to the ADC 61. The The reflected wave is a diagram schematically showing an analog signal observed at the input end of the ADC 61. A waveform indicated by an arrow A is a part of a leak detection pulse signal input via a protection diode, and an amplitude is about 0.5 [V]. The waveform indicated by arrow B is a reflected wave of the leak detection pulse signal. As described above, since the other end of the detection cable 11 is terminated by the terminator 13 having an impedance equivalent to the characteristic impedance of the detection cable 11, no reflected wave is normally generated. However, when the characteristic impedance of the detection cable 11 changes due to liquid leakage from a liquid transport pipeline or the like, a reflected wave is generated. Here, an example in which liquid leakage occurs between 16 [m] and 24 [m] is shown.
　ここで、再び図１を参照すると、ＡＤＣ６１でデジタル変換された反射波は、記憶部２３などに処理データとして記憶される。記憶部２３に記憶された処理データに基づいて、液体輸送パイプラインの液体漏洩の有無を判定できる。例えば、処理データは、データＩ／Ｏ部７１を介して、漏洩検出装置１に接続されるＬＣＤディスプレイ装置などの表示装置１１３に、波形グラフなどとして表示することができる。点検者は、この表示を点検することにより、液体輸送パイプラインの液体漏洩の有無を判定できる。また、記憶部２３、又は記憶装置１１５などに記憶された基準データと、処理データとを比較することによって、液体輸送パイプラインの液体漏洩の有無を判定できる。基準データは、漏洩検出装置１を設置する際に計測された計測値に基づいて作成してもよく、又は最新の複数の処理データの平均値などに基づいて作成してもよい。液体漏洩の有無を判定する際に、さらに所定のしきい値を使用してもよい。例えば、処理データと、基準データとの最大の差異値と、所定のしきい値とを比較して、液体漏洩の有無を判定できる。さらにまた、液体漏洩の有無を判定する際に、複数の処理データの平均値を使用してもよい。複数の処理データの平均値を使用することにより、熱雑音など不規則に発生するノイズの影響を除去するためである。好適には、液体漏洩の有無を判定する際には、５０~１００程度の処理データの平均値を使用することが望ましい。例えば、６４個のデータの平均値を使用することができる。 Here, referring to FIG. 1 again, the reflected wave digitally converted by the ADC 61 is stored as processing data in the storage unit 23 or the like. Based on the processing data stored in the storage unit 23, the presence or absence of liquid leakage in the liquid transport pipeline can be determined. For example, the processing data can be displayed as a waveform graph or the like on the display device 113 such as an LCD display device connected to the leak detection device 1 via the data I / O unit 71. The inspector can determine the presence or absence of liquid leakage in the liquid transport pipeline by inspecting this display. Further, by comparing the reference data stored in the storage unit 23 or the storage device 115 with the processing data, it is possible to determine the presence or absence of liquid leakage in the liquid transport pipeline. The reference data may be created based on the measured value measured when the leak detection apparatus 1 is installed, or may be created based on the average value of the latest plurality of processing data. A predetermined threshold value may be further used when determining the presence or absence of liquid leakage. For example, the presence or absence of liquid leakage can be determined by comparing the maximum difference value between the processing data and the reference data with a predetermined threshold value. Furthermore, when determining the presence or absence of liquid leakage, an average value of a plurality of processing data may be used. This is to eliminate the influence of irregular noise such as thermal noise by using the average value of a plurality of processing data. Preferably, when determining the presence or absence of liquid leakage, it is desirable to use an average value of processing data of about 50 to 100. For example, an average value of 64 data can be used.
　このように、漏洩検出装置１では、記憶部２３に記憶されたゲインテーブルを所定のサンプリング周期で読み出して、反射波の伝搬距離に応じた適当な増幅率を反射波に与えることにより、１つの漏洩検出パルス信号に対して、複数の反射波を検出することが可能になる。例えば、４〔ｍ〕ごとに反射波をサンプリングする場合は、１つの漏洩検出パルス信号に対して、１０００〔ｍ〕当たり２５０個の反射波を検出することが可能である。このため、本発明に係る漏洩検出装置１では、１つの漏洩検出パルス信号に対して、１つの反射波を検出する従来の漏洩検出装置と比較して検出時間を大幅に短縮することができる。また、本発明に係る漏洩検出装置１では、単一のパルス生成部３１が生成した信号を使用して、検出ケーブル１１に入射される漏洩検出パルス信号を生成するとともに、ゲインアンプ５３、及びＡＤＣ６１を制御するため、パルス信号、及び反射信号の制御が容易になるとともに、構成素子を削減できるという利点も有する。 As described above, the leak detection apparatus 1 reads the gain table stored in the storage unit 23 at a predetermined sampling period, and gives the reflected wave an appropriate amplification factor according to the propagation distance of the reflected wave. A plurality of reflected waves can be detected with respect to the leakage detection pulse signal. For example, when sampling reflected waves every 4 [m], it is possible to detect 250 reflected waves per 1000 [m] for one leak detection pulse signal. For this reason, in the leak detection apparatus 1 which concerns on this invention, compared with the conventional leak detection apparatus which detects one reflected wave with respect to one leak detection pulse signal, detection time can be shortened significantly. Further, in the leak detection apparatus 1 according to the present invention, a leak detection pulse signal incident on the detection cable 11 is generated using the signal generated by the single pulse generation unit 31, and the gain amplifier 53 and the ADC 61 are also generated. Therefore, it is easy to control the pulse signal and the reflected signal, and there is an advantage that the number of constituent elements can be reduced.
　次に図５を参照して、漏洩検出装置１を使用して、液体輸送パイプラインからの液体漏洩を検出する方法の一例について説明する。図５に示すように、ステップ１０１において、ＣＰＵ２１は、所定の周期を有するパルス信号を生成する。このパルス信号に基づいて検出ケーブル１１に入射される漏洩検出パルス信号が生成されるとともに、検出ケーブル１１からの反射波の増幅、及びＡ／Ｄ変換が行われる。次いでステップ１０２において、ＣＰＵ２１は、パルス信号に基づいて生成された漏洩検出パルス信号を検出ケーブルに入射する。そして、適当な時間が経過した後にステップ１０３において、ＣＰＵ２１は、所定のサンプリング信号の周期で、反射波を増幅し、ステップ１０４において、増幅した反射波をアナログ信号からデジタル信号に変換する。そしてステップ１０５において、ＣＰＵ２１は、デジタル信号に変換されたデータを記憶する。 Next, an example of a method for detecting liquid leakage from the liquid transport pipeline using the leakage detection device 1 will be described with reference to FIG. As shown in FIG. 5, in step 101, the CPU 21 generates a pulse signal having a predetermined period. Based on this pulse signal, a leak detection pulse signal incident on the detection cable 11 is generated, and the reflected wave from the detection cable 11 is amplified and A / D converted. Next, at step 102, the CPU 21 causes the leakage detection pulse signal generated based on the pulse signal to enter the detection cable. After a suitable time has elapsed, in step 103, the CPU 21 amplifies the reflected wave at a predetermined sampling signal period, and in step 104, converts the amplified reflected wave from an analog signal to a digital signal. In step 105, the CPU 21 stores the data converted into the digital signal.
　ステップ１０６において、ＣＰＵ２１は、ステップ１０２~１０５が、所定の回数に亘り実行されているか否かを判定する。これらのステップが所定の回数実行されていない場合は、ＣＰＵ２１は、再度ステップ１０２において、漏洩検出パルス信号を検出ケーブルに入射する。これらのステップが所定の回数実行されている場合は、ステップ１０７において、ＣＰＵ２１は、平均化などさらなる処理が施された処理データと、所与の基準データとを比較して、液体輸送パイプラインに液体漏洩が発生しているか否かを判定する。 In step 106, the CPU 21 determines whether or not steps 102 to 105 have been executed a predetermined number of times. If these steps have not been executed a predetermined number of times, the CPU 21 again enters the leak detection pulse signal into the detection cable in step 102. If these steps have been executed a predetermined number of times, in step 107, the CPU 21 compares the processing data that has undergone further processing such as averaging with the given reference data, and enters the liquid transport pipeline. It is determined whether or not liquid leakage has occurred.
　図６において、本発明に係る漏洩検出装置の他の例を示す。図６に示すように、漏洩検出装置３は、検出センサ１１と、信号処理部４とを有する。漏洩検出装置３が備える信号処理部４は、漏洩検出装置１が備える信号処理部２と比較すると、遅延量選択部８１を有している点が相違する。したがって、ここでは、相違点である遅延量選択部８１に関する事項を主に説明し、先に説明した事項と重複する事項に関する説明は、省略する。 FIG. 6 shows another example of the leak detection apparatus according to the present invention. As shown in FIG. 6, the leak detection device 3 includes a detection sensor 11 and a signal processing unit 4. The signal processing unit 4 included in the leakage detection device 3 is different from the signal processing unit 2 included in the leakage detection device 1 in that it includes a delay amount selection unit 81. Therefore, here, the matters relating to the delay amount selection unit 81 which is the difference will be mainly described, and the explanation relating to the matters overlapping with the matters described above will be omitted.
　図６に示すように、遅延量選択部８１は、パルス生成部３１が生成したパルス信号を受信するとともに、ＣＰＵ２１から選択信号を受信して、選択信号で選択された遅延量だけ遅延したパルス信号をサンプリング信号として、ＣＰＵ２１、及びＡＤＣ６１に提供する。すなわち、遅延量選択部８１は、パルス生成部３１が生成したパルス信号に対して、選択された遅延量で遅延させたタイミングで、ゲインアンプ５３、及びＡＤＣ６１での処理を実行することが可能である。これによって、遅延量選択部８１を有しない漏洩検出装置１よりも、高い分解能で漏洩検出が可能になる。すなわち、漏洩検出パルス信号の周期の間の時間を、遅延量選択部８１で遅延させたサンプリング信号によりサンプリングすることによって、検出ケーブル１１の計測距離間隔を短くし、分解能を向上させることが可能である。 As shown in FIG. 6, the delay amount selection unit 81 receives the pulse signal generated by the pulse generation unit 31 and also receives the selection signal from the CPU 21 and is delayed by the delay amount selected by the selection signal. Is provided to the CPU 21 and the ADC 61 as a sampling signal. That is, the delay amount selection unit 81 can execute processing in the gain amplifier 53 and the ADC 61 at a timing delayed by the selected delay amount with respect to the pulse signal generated by the pulse generation unit 31. is there. As a result, leak detection can be performed with higher resolution than the leak detection device 1 that does not include the delay amount selection unit 81. That is, it is possible to shorten the measurement distance interval of the detection cable 11 and improve the resolution by sampling the time between the periods of the leakage detection pulse signal with the sampling signal delayed by the delay amount selection unit 81. is there.
　遅延量選択部８１を有する漏洩検出装置３の動作を、上述した比誘電率εが１．５である多孔質ＰＴＦＥを有する検出ケーブル１１を使用し、パルス信号発生部３１が発生するパルス信号の周波数が３１．２５〔ＭＨｚ〕の場合を例に説明する。この例では、パルス信号の周期は、３２〔ｎｓ〕であり、検出ケーブル１１のサンプリング距離間隔に換算すると、４〔ｍ〕に相当する。このパルス信号を、図７で示すような回路などで構成される遅延量選択部８１に印加する場合を考える。図７に示すように、遅延量選択部８１は、パルス生成部３１が発生したパルス信号を、遅延素子８３ａ、８３ｂ、及び８３ｇなどを介することによって遅延したパルス信号を、選択信号により制御されるセレクタ８５により選択して、ＡＤＣ６１、及びＣＰＵ２１などに提供する。まず、図８のタイミングチャートに示すように、図７に示すセレクタ８５がＤｉｎ０に入力されたパルス信号をＤｏｕｔに出力する場合、パルス信号がサンプリングする地点が、順に０〔ｍ〕、４〔ｍ〕、８〔ｍ〕、．．．、９９２〔ｍ〕、９９６〔ｍ〕、１０００〔ｍ〕、．．．に対応すると仮定する。すると、Ｄｉｎ０に入力されるパルス信号よりも４〔ｎｓ〕遅延したＤｉｎ１に入力されたパルス信号をＤｏｕｔに出力する場合、サンプリングする地点は、０．５〔ｍ〕、４．５〔ｍ〕、８．５〔ｍ〕、．．．、９９２．５〔ｍ〕、９９６．５〔ｍ〕、１０００．５〔ｍ〕、．．．に対応する。これは、双方のパルス信号の遅延差である４〔ｎｓ〕が、検出ケーブル１１の距離間隔では、０．５〔ｍ〕に対応するためである。同様に、Ｄｉｎ０に入力されるパルス信号よりも８〔ｎｓ〕遅延したＤｉｎ２に入力されたパルス信号をＤｏｕｔに出力する場合、サンプリングする地点は、１〔ｍ〕、５〔ｍ〕、９〔ｍ〕、．．．、９９３〔ｍ〕、９９７〔ｍ〕、１００１〔ｍ〕、．．．に対応する。以下、同様に、Ｄｉｎ０に入力されるパルス信号よりも２８〔ｎｓ〕遅延したＤｉｎ７に入力されるパルス信号まで、４〔ｎｓ〕、すなわち０．５〔ｍ〕の分解能で、検出ケーブル１１の反射波を検出することができる。 The operation of the leakage detection device 3 having the delay amount selection unit 81 is performed by using the detection cable 11 having the porous PTFE having the relative dielectric constant ε of 1.5 described above and the pulse signal generated by the pulse signal generation unit 31. A case where the frequency is 31.25 [MHz] will be described as an example. In this example, the period of the pulse signal is 32 [ns], which corresponds to 4 [m] when converted to the sampling distance interval of the detection cable 11. Consider a case in which this pulse signal is applied to a delay amount selection unit 81 configured by a circuit as shown in FIG. As shown in FIG. 7, the delay amount selection unit 81 controls a pulse signal obtained by delaying the pulse signal generated by the pulse generation unit 31 through delay elements 83a, 83b, 83g, and the like by the selection signal. The data is selected by the selector 85 and provided to the ADC 61 and the CPU 21. First, as shown in the timing chart of FIG. 8, when the selector 85 shown in FIG. 7 outputs the pulse signal input to Din0 to Dout, the sampling points of the pulse signal are 0 [m], 4 [m] in order. ], 8 [m],. . . , 992 [m], 996 [m], 1000 [m],. . . Is assumed to correspond. Then, when the pulse signal input to Din1 delayed by 4 [ns] from the pulse signal input to Din0 is output to Dout, sampling points are 0.5 [m], 4.5 [m], 8.5 [m],. . . 992.5 [m], 996.5 [m], 1000.5 [m],. . . Corresponding to This is because 4 [ns], which is the delay difference between both pulse signals, corresponds to 0.5 [m] in the distance interval of the detection cable 11. Similarly, when the pulse signal input to Din2 delayed by 8 [ns] from the pulse signal input to Din0 is output to Dout, sampling points are 1 [m], 5 [m], and 9 [m]. ],. . . , 993 [m], 997 [m], 1001 [m],. . . Corresponding to Hereinafter, similarly, the reflection of the detection cable 11 with a resolution of 4 [ns], that is, 0.5 [m], until the pulse signal input to Din7 delayed by 28 [ns] from the pulse signal input to Din0. Waves can be detected.
　このように、パルス信号を適当な遅延量で遅延させて、反射波をサンプリングすることによって、パルス生成部３１が発生するパルス信号の周波数を高くすることなく、検出ケーブル１１の分解能を上げることができる。一般に、ＣＰＵ、ＤＡＣ、ＡＤＣなどの電子機器の動作速度、及び分解能などの性能が許す限り、サンプリング周波数を高速化することは、可能である。しかしながら、サンプリング周波数を高速化した場合は、データレートが高い信号処理回路、及びＣＰＵを使用する必要がある。一般に、ＡＤＣ５１、及びＤＡＣ６１などの電子部品は、定格のサンプリング周波数が高くなると、その価格は、指数関数的に上昇する。また、高周波動作に対応するために、電子回路基板もまた、耐雑音性能が高い高価な基板を使用する必要がある。このため、パルス生成部３１が生成するパルス信号の周波数を高くすると、信号処理部４を構成するそれぞれの素子の価格が上昇するため、製造コストの上昇を招くおそれがある。さらに、サンプリング周波数の高速化に伴い、信号間のジッタが発生する可能性が高まり、信頼性が低下するおそれもある。遅延量選択部８１を有する漏洩検出装置３では、異なる遅延量でパルス信号を遅延させた複数の信号をサンプリング信号として使用することにより、パルス生成部３１が発生するパルス信号の周波数を上げることなく、分解能を上げることができる。例えば、３１．２５〔ＭＨｚ〕など周波数を発生する汎用パルス生成部を使用した場合でも、十分に分解能が高く、かつ信頼性のあるデータを短時間に取得できる。 As described above, by delaying the pulse signal by an appropriate delay amount and sampling the reflected wave, the resolution of the detection cable 11 can be increased without increasing the frequency of the pulse signal generated by the pulse generator 31. it can. In general, it is possible to increase the sampling frequency as long as the operation speed of electronic devices such as a CPU, DAC, and ADC, and performance such as resolution allow. However, when the sampling frequency is increased, it is necessary to use a signal processing circuit and a CPU having a high data rate. In general, the price of electronic components such as the ADC 51 and the DAC 61 increases exponentially as the rated sampling frequency increases. In order to cope with high-frequency operation, the electronic circuit board must also use an expensive board with high noise resistance. For this reason, if the frequency of the pulse signal generated by the pulse generation unit 31 is increased, the price of each element constituting the signal processing unit 4 increases, which may increase the manufacturing cost. Furthermore, as the sampling frequency is increased, the possibility of jitter between signals increases, and the reliability may be reduced. In the leak detection device 3 having the delay amount selection unit 81, a plurality of signals obtained by delaying the pulse signal by different delay amounts are used as sampling signals without increasing the frequency of the pulse signal generated by the pulse generation unit 31. , Can increase the resolution. For example, even when a general-purpose pulse generation unit that generates a frequency such as 31.25 [MHz] is used, data with sufficiently high resolution and reliability can be acquired in a short time.
　次に図９を参照して、遅延量選択部８１を有する漏洩検出装置３を使用して、液体輸送パイプラインからの液体漏洩を検出する方法の一例について説明する。図９に示すように、ステップ２０１において、ＣＰＵ２１は、遅延量選択部８１に選択信号を提供する。ステップ２０２~２０７は、図５のステップ１０１~１０６と同様である。ステップ２０８において、所定の回数に亘り漏洩検出パルスを検出ケーブル１１に入射して、反射信号を記憶した後に、ＣＰＵ２１は、遅延量選択部８１において選択されていない遅延量があるか否かを判定する。選択されていない遅延量がある場合は、処理は、ステップ２０１に戻る。また全ての遅延量を選択している場合は、ステップ２０９において、ＣＰＵ２１は、異なる遅延量で遅延させた処理データを１つのデータに結合する。処理データを結合することにより、分解能が向上した処理データを得ることができる。そして、ステップ２１０において、処理データは、基準データと比較される。 Next, an example of a method for detecting a liquid leak from the liquid transport pipeline using the leak detection device 3 having the delay amount selection unit 81 will be described with reference to FIG. As shown in FIG. 9, in step 201, the CPU 21 provides a selection signal to the delay amount selection unit 81. Steps 202 to 207 are the same as steps 101 to 106 in FIG. In step 208, after the leakage detection pulse is incident on the detection cable 11 for a predetermined number of times and the reflected signal is stored, the CPU 21 determines whether or not there is a delay amount not selected by the delay amount selection unit 81. To do. If there is an unselected delay amount, the process returns to step 201. If all the delay amounts are selected, in step 209, the CPU 21 combines the processing data delayed by different delay amounts into one data. By combining the processing data, processing data with improved resolution can be obtained. In step 210, the processed data is compared with the reference data.
　以上、添付図面を参照しながら本発明の実施形態を説明したが、各種の変形例があり得るのはいうまでもない。 As mentioned above, although embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that various modifications are possible.
　例えば、本発明を使用して、輸送パイプラインの漏洩箇所を特定するだけでなく、漏洩検出ケーブルの欠陥箇所を特定することもできる。また、本明細書においては、比誘電率εが１．５の多孔質ＰＴＦＥを有する同軸ケーブルを、検出ケーブルとして使用する漏洩検出装置について説明してきた。しかしながら、誘電率が異なる多孔質ＰＴＦＥを有する検出ケーブル、又は他の樹脂を絶縁体材料とする検出ケーブルを検出ケーブルとして使用することもできる。さらにまた、本明細書において、漏洩検出パルス信号は、サンプリング信号を生成するパルス生成部３１の信号により生成されるが、他のパルス発生器により生成することもできる。 For example, the present invention can be used not only to identify a leak location in a transport pipeline, but also to identify a fault location in a leak detection cable. Further, in the present specification, a leakage detection apparatus that uses a coaxial cable having porous PTFE having a relative dielectric constant ε of 1.5 as a detection cable has been described. However, a detection cable having porous PTFE having a different dielectric constant or a detection cable using another resin as an insulating material can also be used as the detection cable. Furthermore, in this specification, the leak detection pulse signal is generated by the signal of the pulse generation unit 31 that generates the sampling signal, but can also be generated by another pulse generator.
　１、３　　漏洩検出装置
　２、４　　信号処理部
　１１　　検出センサ
　１３　　終端器
　１５　　ダミーケーブル
　２１　　ＣＰＵ
　３１　　パルス生成部
　３３　　パルス幅制御部
　４１　　Ｉ／Ｏ部
　５１　　ＤＡＣ
　５３　　ゲインアンプ
　６１　　ＡＤＣ
　７１　　データＩ／Ｏ
　８１　　遅延量選択部
　１００　　液体輸送パイプライン
　１１１　　入力装置
　１１３　　表示装置
　１１５　　記憶装置 DESCRIPTION OF SYMBOLS 1, 3 Leak detection apparatus 2, 4 Signal processing part 11 Detection sensor 13 Terminator 15 Dummy cable 21 CPU
31 Pulse Generation Unit 33 Pulse Width Control Unit 41 I / O Unit 51 DAC
53 gain amplifier 61 ADC
71 Data I / O
81 Delay amount selection unit 100 Liquid transport pipeline 111 Input device 113 Display device 115 Storage device

Claims (6)

  1. 　漏洩検出ケーブルに入射される漏洩検出パルス信号の反射波を検出することによって、液体輸送パイプラインからの液体漏洩を検出する装置であって、
    　前記パイプラインに沿って敷設され、前記パイプラインから漏洩した液体が浸透することにより特性インピーダンスが変化する漏洩検出ケーブルと、
    　前記漏洩検出ケーブルに入射される漏洩検出パルス信号を生成する漏洩検出パルス信号生成部と、
    　前記反射波の伝播距離と、該反射波の減衰との相関を表すデータを記憶する記憶部と、
    　所定のサンプリング周期で繰り返されるサンプリング信号に同期して、前記漏洩検出パルス信号に対する前記反射波を増幅するゲインアンプであって、前記データに基づいて、前記反射波の増幅率を変更する増幅率可変ゲインアンプと、
    　前記サンプリング信号に同期して、１つの前記漏洩検出パルス信号に対する前記増幅された反射波を複数回サンプリングし、該サンプリングした反射波をデジタル信号に変換するＡ／Ｄ変換部と、
    　を有することを特徴とする装置。     An apparatus for detecting liquid leakage from a liquid transport pipeline by detecting a reflected wave of a leakage detection pulse signal incident on a leakage detection cable,
    Leakage detection cable that is laid along the pipeline and has a characteristic impedance that changes due to penetration of liquid leaked from the pipeline;
    A leak detection pulse signal generation unit for generating a leak detection pulse signal incident on the leak detection cable;
    A storage unit for storing data representing a correlation between the propagation distance of the reflected wave and the attenuation of the reflected wave;
    A gain amplifier that amplifies the reflected wave with respect to the leakage detection pulse signal in synchronization with a sampling signal repeated at a predetermined sampling period, and an amplification factor variable that changes an amplification factor of the reflected wave based on the data A gain amplifier,
    An A / D converter that samples the amplified reflected wave for one leak detection pulse signal a plurality of times in synchronization with the sampling signal, and converts the sampled reflected wave into a digital signal;
    A device characterized by comprising:
  2. 　前記サンプリング信号を、前記サンプリング周期の１／Ｎずつ遅延量が異なるＮ個の遅延量で遅延可能な遅延量選択部であって、前記Ｎは整数である遅延量選択部をさらに有する請求項１に記載の装置。 2. The delay amount selection unit capable of delaying the sampling signal by N delay amounts having different delay amounts by 1 / N of the sampling period, wherein the N is an integer. The device described in 1.
  3. 　前記デジタル信号と、所与の基準値とを比較して、前記パイプライン等から漏洩の有無が判定される請求項１、又は請求項２に記載の装置。 3. The apparatus according to claim 1, wherein the digital signal and a given reference value are compared to determine whether there is leakage from the pipeline or the like.
  4. 　液体輸送パイプライン等からの液体漏洩を検出する方法であって、
    　漏洩検出パルス信号を漏洩検知ケーブルに入力するステップと、
    　所定のサンプリング周期を有するサンプリング信号に同期して、前記漏洩検出パルス信号の反射波を増幅するステップと、
    　前記サンプリング信号に同期して、前記増幅された反射波をサンプリングし、かつ該サンプリングした反射波をデジタル信号に変換するステップと、
    　を有することを特徴とする方法。     A method for detecting liquid leakage from a liquid transport pipeline, etc.
    Inputting a leak detection pulse signal to the leak detection cable;
    Amplifying a reflected wave of the leakage detection pulse signal in synchronization with a sampling signal having a predetermined sampling period;
    Sampling the amplified reflected wave in synchronization with the sampling signal and converting the sampled reflected wave into a digital signal;
    A method characterized by comprising:
  5. 　反射波を増幅する前記ステップ、及び前記増幅された反射波をデジタル信号に変換する前記ステップの前記サンプリング周期を、前記サンプリング周期の１／Ｎずつ遅延量が異なるＮ個のタイミングずつシフトさせて、それぞれ実行する方法であって、前記Ｎは整数である請求項４に記載の方法。 The sampling period of the step of amplifying a reflected wave and the step of converting the amplified reflected wave to a digital signal is shifted by N timings with different delay amounts by 1 / N of the sampling period, The method of claim 4, wherein each method is performed, wherein N is an integer.
  6. 　前記デジタル信号と、所与の基準値とを比較して、前記パイプライン等から漏洩の有無を判定するステップをさらに有する請求項４、又は請求項５に記載の方法。 6. The method according to claim 4, further comprising the step of comparing the digital signal with a given reference value to determine whether there is leakage from the pipeline or the like.
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