JP3212501B2 - Pipe clogging detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe for detecting the clogging of a pipe such as a guide pipe serving as a conduit for grain transportation, a pipe for supplying metal cutting chips and metal pieces, and a chute using ultrasonic waves. The present invention relates to a clogging detection method and device.

[0002]

2. Description of the Related Art Conventionally, for example, a guide pipe has been generally used as a conduit for grain transportation, and a pipe or chute has been generally used as a transport pipe for cut fuel rods in a fuel rod reprocessing system for nuclear power generation. I have. In this case, a pipe inspection system that monitors the status of a pipe such as a guide pipe or a chute and detects when the pipe is clogged is required.

FIG. 4 shows an example of such a pipe inspection system. An ultrasonic sensor 43 is installed at a metal piece input port of a pipe 41 on which a metal piece cut by a shearing machine falls. The ultrasonic wave is transmitted to the inside of the pipe 41 by the ultrasonic wave sensor 43, and the reflected wave generated in the clogged portion 42 is received by the ultrasonic wave sensor 43, and a signal waveform of the received reflected wave (hereinafter, referred to as a reflected signal waveform) is formed. The clogged portion 42 is detected by the transmitter / receiver 44 based on the result, and the result is displayed on the display device 45.

[0004] Here, since there are joints, bolts and nuts, screws, holes, holes, dents, and the like (hereinafter, referred to as shape-changed portions) in the pipe 41, a clogged portion 42 is detected.
It is necessary to separate and detect the reflected wave generated at the clogged portion 42 and the reflected wave generated at the shape change portion. Therefore, conventionally, a reflected signal waveform obtained in a state where the pipe 41 is empty is registered in advance as a reference signal waveform, and the reference signal waveform is subtracted from the signal waveform of the reflected wave obtained at the time of actual clogging detection, whereby clogging is performed. A method is employed in which the reflected signal waveform generated at the portion 42 is extracted, and the clogged portion 42 is detected based on the extracted signal waveform. For example, if the reference signal waveform as shown in FIG. 5A is subtracted from the reflected signal waveform as shown in FIG. 5B, the signal waveform component of the reflected wave from the shape-changed portion is canceled out, and FIG. As shown in (c), a reflected signal waveform representing only the clogged portion 42 is obtained.

In this case, if the temperature in the pipe 41 when the reference signal waveform is measured is different from the temperature in the pipe 41 when the actual clogging is detected, the propagation time of the reflected wave in the pipe 41 is different. Therefore, the delay time of the reflected wave from the shape-changed portion differs between the measurement of the reference signal waveform and the detection of clogging, so that the signal waveform component of the reflected wave from the shape-changed portion cannot be canceled. Then, an error occurs in clogging detection.

Therefore, conventionally, a temperature sensor is provided inside the pipe 41, and the change rate σ of the propagation time of the reflected wave is calculated from the temperature t when the reference signal is measured and the temperature tr when the clogging is detected by the following equation. Then, the reflected signal waveform is corrected by the change rate σ.

[0007]

(Equation 1) Here, v is a reference value of the sound speed in the atmosphere, and dv is a change in the sound speed depending on the temperature.

[0008]

As described above, conventionally, a temperature sensor is provided inside a pipe, and the temperature inside the pipe is measured when an actual clog is detected to correct the reflected signal waveform.
However, depending on the structure of the piping or the application of the piping, there is a problem that it is troublesome or difficult to provide a temperature sensor inside. Another problem is that accurate detection cannot be performed if the temperature sensor provided inside the pipe breaks down.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and an apparatus for detecting clogging in a pipe, which can detect clogging without measuring the temperature inside the pipe when detecting clogging. Aim.

[0010]

SUMMARY OF THE INVENTION A method for detecting clogging in a pipe according to the present invention is to transmit an ultrasonic wave from a predetermined position of a pipe having a shape change portion inside the pipe to a shape change portion and a blockage portion inside the pipe. In the pipe clogging detection method of receiving a reflected wave from the pipe and detecting a clogging of the pipe based on the signal waveform of the reflected wave, the pipe is obtained by transmitting ultrasonic waves to the inside of the pipe in a state where the inside of the pipe is empty in advance. The signal waveform and the delay time of the reflected wave from the shape change portion are registered as the reference signal waveform and the reference time, respectively, and the time change range set corresponding to the previously estimated temperature change range is registered, and the actual time change range is registered. when clogging detection, the pipe inside seek the delay time of the reflected waves from the shape-changing portion and the clogging portion obtained by transmitting ultrasonic waves, the reference period
The delay corresponding to each shape-change portion indicated by
Delay time is compared and detected only within the time change range.
And, calculating a rate of change relative to the reference time of the delay time, the signal waveform of the reflected wave is corrected based on the rate of change,
A blockage of the pipe is detected based on a signal waveform obtained by subtracting a reference signal waveform from the corrected signal waveform. Here, the shape-changing portion is a joint of the pipe existing in the pipe, a bolt and nut, a screw, a hole, a hole, a dent, or a reflection plate or the like installed so as not to hinder the passage of a substance passing through the pipe. .

An apparatus for detecting clogging in a pipe according to the present invention transmits ultrasonic waves from a predetermined position of a pipe having a shape-changed portion to the inside of the pipe, and receives reflected waves from the shape-changed portion and the clogged portion in the pipe. Then, in a pipe clogging detection device that detects pipe clogging based on the signal waveform of the reflected wave, reflection from a shape change portion obtained by transmitting ultrasonic waves to the inside of the pipe in advance when the inside of the pipe is empty. Registering the signal waveform and the delay time of the wave as a reference signal waveform and a reference time, respectively, and registering a time change range set corresponding to a temperature change range estimated in advance ; The delay time of the reflected wave from the shape-changed portion and the clogged portion obtained by transmitting ultrasonic waves inside the pipe is obtained, and the delay time is indicated by the reference time.
The delay time corresponding to each shape change portion to be performed,
A change rate calculation unit that compares and detects only the time change range and calculates a change rate of the delay time with respect to the reference time, and corrects a signal waveform of the reflected wave based on the change rate, and performs the correction. Clogging detection means for detecting clogging of a pipe based on a signal waveform obtained by subtracting a reference signal waveform from a signal waveform.

As described above, according to the present invention, the delay time of the reflected wave from the shape change portion is registered as the reference time when the reference signal waveform is measured with the inside of the pipe being empty, and the measured value corresponds to the temperature change range estimated in advance. The time change range set in advance is registered, and when an actual blockage is detected ,
Shape change and clogging obtained by transmitting ultrasonic waves to the part
Find the delay time of the reflected wave from the part and register the reference time
Delay corresponding to each shape change indicated by the interval
Compare the time only within the registered time change range.
By calculating the rate of change of the delay time with respect to the reference time, it is not necessary to measure the temperature in the pipe to calculate the rate of change as in the conventional case, and highly reliable clogging detection can be performed. Become.

[0013]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention. This system detects clogging of a pipe 1 on which a metal piece cut by a shearing machine falls, and specifies the position of the clogged portion 3.
The pipe 1 is provided with a joint whose position is known, a bolt and nut, a screw, a hole, a hole, a hollow, or a reflection plate or the like (hereinafter, referred to as a reflector) installed in the pipe so as not to prevent the metal piece from dropping.
It is assumed that there is a shape change portion 2) and a clogged portion 3 is caused by the accumulation of metal pieces.

This system detects a blockage in the pipe 1 in two main steps. That is, an ultrasonic wave is transmitted into the pipe 1 in advance with the pipe 1 empty, and the signal waveform (reference signal waveform) and the delay time (reference time) of the reflected wave from the shape change portion 2 are registered. The ultrasonic wave is transmitted into the pipe 1 in a state where the metal piece cut by the shearing machine falls in the pipe 1, the signal waveform and the delay time of the reflected wave are obtained, and the reference signal waveform and the reference time in which these are registered. By comparing with
Detects internal clogs.

In this system, an ultrasonic sensor 4 is installed at a metal piece inlet of the pipe 1. The ultrasonic sensor 4 is driven by an oscillation signal output from the transmitter / receiver 5 to transmit ultrasonic waves to the inside of the pipe 1, and receives reflected waves of the ultrasonic waves from the shape changing portion 2 and the clogging portion 3. And converts it into an electric signal, and outputs it to the transducer 5 as a reflected signal waveform.

The transmitter / receiver 5 outputs a trigger signal indicating the start of oscillation to the propagation time correction device 6 at both the time of registration and the time of detection of clogging, and causes the ultrasonic sensor 4 to oscillate at a predetermined voltage and frequency. The signal is output, and the reflected signal waveform output from the ultrasonic sensor 4 is appropriately amplified and output to the propagation time correction device 6.

The propagation time correction device 6 registers the reflected signal waveform output from the transmitter / receiver 5 as a reference signal waveform at the time of registration, and also registers this delay time as a reference time. The clogging of the pipe 1 is detected based on the trigger signal and the reflected signal waveform output from the reference signal 5 and the registered reference signal waveform and reference time, and the result is output to the display device 6.

FIG. 2 is a block diagram showing the configuration of the propagation time correction device 6. The propagation time correction device 6 includes a reference signal waveform registration buffer 21, a reference time registration buffer 22,
It has an A / D (analog / digital) conversion circuit 23, a reflected signal detection circuit 24, a signal waveform correction circuit 25, and a pipe blockage detection circuit 26.

The reference signal waveform registration buffer 21 registers a reference signal waveform as shown in FIG. 3A, for example. The reference time registration buffer 22 stores a reference time Sr (i) (i = 0, 1, 1) as shown in FIG.
..), And a reference time change range δs (i), which is set based on the internal temperature of the pipe 1 at the time of registration, is also registered.

The A / D conversion circuit 23 converts the trigger signal and the reflected signal waveform input from the transducer 5 into a digital signal and outputs the digital signal to the reflected signal detecting circuit 24. The reflection signal detection circuit 24 first determines a delay time of a reflected wave from the shape change portion 2 and the clogged portion 3 (hereinafter referred to as clog detection delay) based on a trigger signal and a reflection signal waveform output from the A / D conversion circuit 23. (Referred to as time) S (i) (i =
0, 1, ...). Next, the reflection signal detection circuit 24
Based on the clog detection delay time S (i) and the reference time Sr (i) registered in the reference time registration buffer 22, the reference time Sr of the clog detection delay time S (i) is determined.
The change rate σ for (i) is obtained, and this change rate σ is output to the signal waveform correction circuit 25 together with the reflected signal waveform. At this time, for example, as shown in FIGS.
For the clogging detection delay time S (i) (i = 1 to 3) corresponding to the reference time Sr (i) (i = 1 to 3), a change rate σ (i) (i = 1 to 3) is obtained. , And their average value is defined as a change rate σ.

At this time, before and after each value of the reference time Sr (i), it corresponds to each shape change portion 2 indicated by the reference time Sr (i) of the clogging detection delay time S (i). The clog detection delay time S (i) is detected, and the reference time Sr corresponding to the same shape change portion 2 is detected.
The change rate σ (i) is obtained from (i) and the clogging detection delay time S (i). In the present embodiment, the reference time Sr
With respect to (i), only the reference time change range δs (i), which will be described later, which indicates the fluctuation range of the reference time Sr (i) registered in the reference time registration buffer 22 due to the temperature, is compared, so that the same shape is obtained. The delay time corresponding to the changing part 2 is detected at high speed.

The reference time change range δs (i) is δt, the change range of the temperature estimated in advance, v is the reference value of the sound speed in the atmosphere, dv is the change amount of the sound speed due to temperature, and the distance to each shape change portion. Is Li (i = 0, 1,...), And the temperature in the pipe 1 at the time of registration of the reference signal waveform and the reference time is t.
r is calculated by the following equation.

[0023]

(Equation 2)

The signal waveform correction circuit 25 corrects the reflected signal waveform based on the change rate σ output from the reflected signal detection circuit 24, and outputs this to the pipe clogging detection circuit 26. The pipe blockage detection circuit 26 first subtracts the reference signal waveform registered in the reference signal waveform registration buffer 21 from the reflected signal waveform corrected by the signal waveform correction circuit 25. As a result, for example, as shown in FIG. 3C, the reflected signal waveform component of the shape change portion 2 corresponding to the reference signal waveform in the reflected signal waveform is canceled. Next, the pipe clogging detection circuit 26 compares the remaining reflected signal waveform as a result of subtracting the reference signal waveform from the reflected signal waveform with a preset threshold value, Is
Assuming that the clogged portion 3 exists in the pipe 1, a clogging detection signal is output to the display device 7. Display device 7 of FIG.
Displays warning information when a signal of clogging detection is output from the propagation time correction device 7.

Hereinafter, the operation of this system will be described. When the system is started, a trigger signal for starting oscillation is output from the transducer 5 to the propagation time correction device 6, and an ultrasonic signal is transmitted from the ultrasonic sensor 4 into the pipe 1 by the oscillation signal output from the transducer 5. Is done.

The transmitted ultrasonic wave propagates through the medium in the pipe 1 and generates reflected waves at the shape changing portion 2 and the clogging portion 3. The reflected wave is received by the ultrasonic sensor 4, and the reflected signal waveform of the received reflected wave is input to the propagation time correction device 6 via the transducer 5.

In the propagation time correction device 6, first, the trigger signal and the reflected signal waveform are converted into digital signals in the A / D conversion circuit 23. Next, the clogging detection delay time S (i) is calculated based on the trigger signal converted into a digital signal and the reflection signal waveform in the reflection signal detection circuit 24, and the clogging detection delay time S (i) is further referred to as a reference. Reference time Sr registered in time registration buffer 22
The change rate σ is obtained based on (i) and the reference time change range δs (i). Next, the signal waveform correction circuit 25 corrects the reflected signal waveform based on the change rate σ. Next, the reference signal waveform registered in the reference signal waveform registration buffer 21 is subtracted from the reflected signal waveform corrected by the signal waveform correction circuit 25 in the pipe clogging detection circuit 26, and the remaining reflected signal waveform is clogged. When the portion 3 is detected, a clogging detection signal is output and the display device 7
Is displayed to that effect.

As described above, according to the present embodiment, the signal waveform and the delay time obtained by transmitting the ultrasonic wave to the inside of the pipe while the inside of the pipe is empty are registered in advance as the reference signal waveform and the reference time, respectively. By calculating the rate of change of the clog detection delay time obtained at the time of actual clog detection with respect to the reference time, it is possible to change the shape from the reflected signal waveform at the time of clog detection without measuring the pipe temperature at the time of actual clog detection. Since the reflected signal waveform components of the portions can be surely canceled out, it is possible to perform highly reliable clogging detection.

Further, a reference time change estimated based on a change in the temperature in the pipe at the time of registration of the reference signal waveform and the reference time is registered in advance as a reference time change range. By comparing only the reference time change range with the clog detection delay time obtained when clogging is detected, the delay time corresponding to the same shape change portion can be detected at high speed.

[0030]

As described above, according to the present invention, there is provided a method and an apparatus for detecting clogging in a pipe, which can detect the clogging without measuring the temperature inside the pipe when detecting the clogging.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a propagation time correction device in FIG. 1;

FIG. 3 is an exemplary view for explaining a correction operation of a reflected signal waveform in the embodiment.

FIG. 4 is a diagram illustrating a conventional method for detecting clogging in a pipe using ultrasonic waves.

FIG. 5 is a diagram for explaining the principle of a clogging detection method using ultrasonic waves.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piping 2 ... Shape change part 3 ... Clogged part 4 ... Ultrasonic sensor 5 ... Transceiver 6 ... Propagation time correction device 7 ... Display device 21 ... Reference signal waveform registration buffer 22 ... Reference time registration buffer 23 ... A / D Conversion circuit 24 ... Reflection signal detection circuit 25 ... Signal waveform correction circuit 26 ... Plumbing clogging detection circuit 41 ... Piping 42 ... Clogged portion 43 ... Ultrasonic sensor 44 ... Transmitter / receiver 45 ... Display device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-75554 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 17/00-17/08 G01N 29 / 00-29/28

Claims (2)

(57) [Claims] An ultrasonic wave is transmitted into a pipe from a predetermined position of a pipe having a shape change portion inside, and a reflected wave from a shape change portion and a clogged portion inside the pipe is received, and a signal waveform of the reflected wave is received. In the method for detecting clogging in a pipe, which detects clogging of the pipe based on a signal waveform and a delay time of a reflected wave from the shape-changed portion obtained by transmitting an ultrasonic wave into the pipe in an empty state in advance. Are registered as a reference signal waveform and a reference time, respectively, and a time change range set corresponding to a temperature change range estimated in advance is registered, and when an actual clog is detected, an ultrasonic wave is transmitted inside the pipe. Obtain the delay time of the reflected wave from the shape-changed portion and the clogged portion obtained by, and indicated by the reference time
The delay time corresponding to each shape change portion,
Comparing and detecting only within the time change range, calculating a change rate of the delay time with respect to the reference time, correcting the signal waveform of the reflected wave based on the change rate,
A method for detecting clogging in a pipe, wherein the clogging of the pipe is detected based on a signal waveform obtained by subtracting the reference signal waveform from the corrected signal waveform. 2. An ultrasonic wave is transmitted from a predetermined position of a pipe having a shape-changed portion to the inside of the pipe, a reflected wave from a shape-changed portion and a clogged portion in the pipe is received, and a signal waveform of the reflected wave is received. In a pipe clogging detection device that detects pipe clogging based on: a signal waveform and a delay time of a reflected wave from the shape-changed portion obtained by transmitting an ultrasonic wave into the pipe in an empty state in advance. together with registers as a reference signal waveform and a reference time, respectively, transmitting a registration unit time variation range set corresponding to the temperature change range registered in advance estimated time of actual clogging detection, an ultrasonic wave inside the pipe From the shape change portion and the clogged portion obtained by
Determine the delay time of the reflected wave, indicated by the reference time
The delay time corresponding to each shape change portion,
A change rate calculating means for comparing and detecting only within the time change range and calculating a change rate of the delay time with respect to the reference time, correcting a signal waveform of the reflected wave based on the change rate,
Clogging detection means for detecting clogging of the pipe based on a signal waveform obtained by subtracting the reference signal waveform from the corrected signal waveform.