JP2010101822A - Apparatus and method for inspecting internal conditions of piping - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect whether a foreign matter such as air bubbles are present or not in a piping of which the condition of being filled with a liquid inside is considered to be normal. <P>SOLUTION: An apparatus for inspecting internal conditions of pipings is provided with an ultrasonic transmitter/receiver 20. The ultrasonic transmitter/receiver 20 is brought into tight contact with the external surface of a piping 7 filled with water inside by cooling water 8. Ultrasonic waves are emitted toward the inside of the piping 7, and reflected waves of the ultrasonic waves are received. Two reflection images 120 and 130 by the internal surface of the piping 7 appear in reception signals 110 by the ultrasonic transmitter/receiver 20. In the case that air bubbles 9 have occurred in the piping 7, a third reflection image 140 appears between the two reflection images 120 and 130 due to the air bubbles 9. By capturing a change in the signal level of the reception signals 110 due to the appearance of the third reflection image 140, the presence or absence of the air bubbles 9 is determined. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pipe internal state inspection apparatus and a pipe internal state inspection method, and more particularly, to a pipe internal state inspection apparatus and a pipe internal state inspection method that inspect the internal state of a pipe using ultrasonic waves.

  A conventional example of this type of technology is disclosed in Patent Document 1. This conventional technique is used, for example, in a steam plant including a pipe that is installed substantially horizontally, to measure the level of drain (condensate) remaining in the pipe. Specifically, an ultrasonic transceiver is attached to the outer surface of the bottom of the pipe. Then, ultrasonic waves are emitted upward from the ultrasonic transmitter / receiver, that is, into the pipe. This ultrasonic wave propagates in the drain staying in the pipe, is reflected by the liquid level of the drain, returns to the propagation path up to that point, and is finally received by the ultrasonic transceiver. As described above, the drain liquid level is determined based on the time taken from the time when the ultrasonic transmitter / receiver emits the ultrasonic wave to the time when the reflected wave from the drain liquid surface of the ultrasonic wave is received. The conventional technology has been devised in such a way that the drain liquid level can be accurately measured even in a dynamic state where the drain liquid level is shaking or wavy. It is a thing. In addition, the conventional technology has a function of judging whether or not the inside of the pipe is full by utilizing the fact that the ultrasonic wave is reflected by the upper inner surface of the pipe when the inside of the pipe is full. Have.

JP 2003-28699 A

  By the way, in various plants including a steam plant, for example, there is a pipe that is always filled with water, and the fluid in the pipe may be designed to naturally flow by the inclination of the pipe. In such a case, if bubbles are generated in the pipe (in the fluid) for some reason, the bubbles may hinder the flow of the fluid, which may lead to a decrease in the operation efficiency of the entire plant. Therefore, if air bubbles are generated in the pipe, if this can be detected, for example, the inner diameter of the pipe is increased (that is, the amount of fluid flowing through the pipe (absolute amount) is increased), or the pipe is lengthened. (That is, increasing the water head pressure (head) in the pipe), and so on, can take appropriate measures, which is extremely useful for the operation of the plant. However, in the above-described prior art, although it can be determined whether or not the inside of the pipe is full, it has not been possible to determine whether or not bubbles are generated in the pipe.

  Therefore, the present invention relates to a pipe internal state inspection device and a pipe internal that can inspect whether or not there is a foreign substance such as a bubble in a pipe that is normally filled with a fluid. An object is to provide a state inspection method.

  In order to achieve this object, the pipe internal state inspection device according to the first aspect of the present invention is a transmitter that is in close contact with the outer surface of a pipe that is normally filled with fluid. And a receiving means provided in the vicinity of the transmitting means or integrally with the transmitting means. Among these, the transmission means transmits ultrasonic waves toward the inside of the pipe, and the reception means receives the reflected waves of the ultrasonic waves. Further, the first invention further includes a determination unit that determines whether or not there is a foreign substance other than the fluid in the pipe based on the reception signal output from the reception unit.

  In this configuration, for example, it is assumed that the fluid is overflowing in the pipe, and there is no foreign matter such as bubbles in the pipe (in the fluid). In this case, the ultrasonic wave transmitted (fired) from the transmission means enters the side wall of the pipe from the outer surface of the pipe. And the ultrasonic wave which entered in this side wall propagates in the said side wall, and reaches | attains the inner surface of piping. Further, a part of the ultrasonic wave that has reached the inner surface of the pipe is reflected by the inner surface, returns to the propagation path up to that point, and is finally received by the receiving means. As a result, the first reflection based on a part of the ultrasonic wave reflected by the inner surface of the pipe, strictly speaking, the inner surface on the side where the transmitting unit is located, that is, the first reflected wave, in the received signal output from the receiving unit. An image appears.

  On the other hand, the remaining ultrasonic waves that have not been reflected by the inner surface of the pipe enter the fluid that overflows in the pipe. Then, the ultrasonic wave that has entered the fluid propagates through the fluid and reaches the inner surface on the opposite side of the pipe, that is, the inner surface on the opposite side to the side on which the transmitting means is located. Is almost totally reflected. The ultrasonic wave substantially totally reflected by the opposite inner surface, that is, the second reflected wave also returns to the propagation path before being reflected and is received by the receiving means. As a result, a second reflected image based on the second reflected wave appears in the reception signal output from the receiving means.

  Note that the time from when the transmitting unit transmits the ultrasonic wave until the receiving unit receives the first reflected wave corresponds to the thickness (thickness) dimension of the side wall of the pipe and is constant. Then, the time from when the receiving means receives the first reflected wave to when the second reflected wave is received, in other words, after the first reflected image appears in the received signal output by the receiving means, the second reflected image appears. The time up to this corresponds to the distance from the inner surface on the side where the transmission means of the pipe is located to the inner surface on the opposite side (for example, the inner diameter when the pipe is a circular pipe), and is also constant.

  Next, consider the case where foreign matter such as bubbles is present in the pipe. In this case, the foreign matter acts as a kind of obstacle for the ultrasonic wave propagating in the pipe (in the fluid) from the side where the transmission means is located toward the opposite side. When the ultrasonic wave collides with the foreign object, the ultrasonic wave is reflected by the foreign object, and the ultrasonic wave reflected by the foreign object, that is, the third reflected wave is finally received by the receiving unit. As a result, a third reflected image based on the third reflected wave appears between the first reflected image and the second reflected image of the reception signal output from the receiving means.

  Thus, when there is a foreign object in the pipe, a third reflected image appears between the first reflected image and the second reflected image of the received signal. That is, the manner of the received signal is different when there is a foreign object in the pipe and when it is not. Focusing on this point, in the first invention, the determining means determines whether or not there is a foreign substance in the pipe based on the received signal.

  Specifically, the determination unit performs the determination based on a signal level in a predetermined period between the first reflected image and the second reflected image in the received signal. That is, as described above, when there is a foreign substance in the pipe, the third reflected image appears between the first reflected image and the second reflected image of the received signal. By monitoring the signal level of the received signal in a predetermined period with the second reflected image, it is determined whether or not the third reflected image has appeared during the predetermined period, and thus whether or not there is a foreign substance in the pipe. Determine whether. Thereby, it is possible to inspect whether or not there is a foreign substance in the pipe.

  In addition, when a foreign object exists in the pipe and an ultrasonic wave is reflected by the foreign object, that is, if a third reflected wave is generated, the part on the inner surface opposite to the side where the transmission means of the pipe is located is provided. The reaching ultrasonic wave decreases, that is, the second reflected wave decreases. As the second reflected wave decreases, the signal level of the second reflected image of the received signal decreases. Utilizing this, the determination means may perform determination based on the signal level of the second reflected image. Note that. The signal level of the first reflected image does not change.

  Further, the larger the foreign object, the third reflected wave increases, and accordingly, the signal level of the third reflected image of the received signal increases, and as a result, the signal level of the received signal in the predetermined period including the third reflected image increases. Change will be greater. Utilizing this fact, the determination means may also determine the size (size) of the foreign matter based on the signal level of the received signal in a predetermined period.

  On the other hand, the larger the foreign object, the more the second reflected wave decreases, and accordingly, the signal level of the second reflected image of the received signal becomes smaller. Therefore, the determination unit may determine the size of the foreign matter based on the signal level of the second reflected image.

  The transmission means transmits ultrasonic waves substantially periodically, the reception means receives a reflected wave every time an ultrasonic wave is transmitted from the transmission means, and the determination means receives the reflected wave by the reception means. A determination may be made each time it is performed. In this case, when the ultrasonic wave collides with a foreign object, a third reflected image appears in the received signal, and otherwise, the third reflected image does not appear. As the amount of foreign matter increases, the frequency at which the third reflected image appears in the received signal increases. In other words, the frequency at which the foreign matter is determined by the determination unit increases. Therefore, in the first invention, a frequency deriving unit that obtains a frequency at which the determination unit determines that a foreign object is present may be further provided. In this way, the amount of foreign matter present in the pipe can be estimated from the frequency obtained by the frequency deriving means.

  2nd invention of this invention is invention regarding the piping internal state inspection method corresponding to 1st invention. That is, the second aspect of the invention is a transmission process of transmitting ultrasonic waves from the transmission means in close contact with the outer surface of the pipe, which is usually in a state where the fluid is overflowing, toward the inside of the pipe, There is a foreign substance other than the fluid in the pipe based on the reception process of receiving the reflected wave of the ultrasonic wave by the reception means provided in the vicinity of the transmission means or integrally with the transmission means, and the reception signal output from the reception means And a determination process for determining whether or not.

  As described above, according to the present invention, it is possible to inspect whether or not a foreign substance such as a bubble is present in a pipe that is normally filled with a fluid. As a result, the entire facility including the piping can be more firmly operated.

  Before describing a specific embodiment of the present invention, first, one case where the present invention is required will be briefly described.

  For example, it is assumed that there is a plant including the evaporative cooling device 1 as shown in FIG. The evaporative cooling device 1 includes a jacket 2 having a substantially U-shaped vertical section. And the to-be-cooled object 4 used as cooling object is accommodated in the accommodating part 3 which is the inner space of the jacket 2. FIG. The jacket 2 has a hollow structure having a hollow evaporative cooling chamber 5, and a cooling water supply pipe 6 for connecting the evaporative cooling chamber 5 to a cooling water supply source (not shown) is coupled to the upper portion thereof. Yes. In addition, another pipe 7 for connecting the vaporization cooling chamber 5 and a vacuum pump (not shown) is coupled to the bottom of the jacket 2. The cooling water supply pipe 6 and the pipe 7 are circular pipes having a circular cross-sectional shape, for example.

  According to the vaporization cooling apparatus 1 configured as described above, the vaporization cooling chamber 5 is depressurized by the above-described vacuum pump, and the cooling water supply pipe 6 is connected to the vaporization cooling chamber 5 in the depressurized state from the above-described cooling water supply source. Cooling water is supplied through This cooling water is vaporized (evaporated) in the vaporization cooling chamber 5, and the object to be cooled 4 is cooled by the latent heat at that time. At the same time, the cooling water that cannot be completely vaporized accumulates in the lower part of the vaporization cooling chamber 5 as indicated by reference numeral 8 in FIG. Then, the cooling water 8 accumulated in the lower part of the evaporative cooling chamber 5 falls in the pipe 7 and is recovered to the vacuum pump side.

  Here, for example, it is assumed that the temperature of the cooling water 8 that cannot be vaporized is relatively high, specifically, close to the saturation temperature corresponding to the pressure of the vaporized cooling chamber 5. Then, the cooling water 8 is re-evaporated (flashed) in the pipe 7, and bubbles 9, 9,... May be generated in the pipe 7 as shown in FIG. These bubbles 9, 9,... Prevent the cooling water 8 from falling, and thus cause a decrease in the operating efficiency of the entire plant, which is extremely undesirable. The present invention is suitable for examining the presence or absence of the bubbles 9, 9,..., And a specific embodiment thereof is as follows.

  That is, as shown in FIG. 3, the pipe internal state inspection device 10 according to the first embodiment of the present invention includes an ultrasonic transmitter / receiver 20 and a device main body 30 to which the ultrasonic transmitter / receiver 20 is connected. ing. Among these, the ultrasonic transmitter / receiver 20 is a so-called probe, and has a conversion element (not shown) that converts electrical signals and ultrasonic waves into each other. And this ultrasonic transmitter-receiver 20 is closely_contact | adhered to the outer surface of the piping 7 so that it may mention later.

  On the other hand, the apparatus main body 30 includes a terminal 32 to which the ultrasonic transceiver 20 is connected. In the apparatus main body 30, the terminal 32 is connected to a drive circuit 34, and the drive circuit 34 is further connected to a CPU (Central Processing Unit) 36 as control means. The CPU 36 controls the operation keys 38 as input means for inputting various commands to the CPU 36, the display 40 as display means for displaying various information based on the processing result by the CPU 36, and the operation of the CPU 36. A memory 42 serving as a storage means in which a control program for storing is stored is connected.

  According to the pipe internal state inspection device 10 configured as described above, the ultrasonic transmitter / receiver 20 (ultrasonic transmitter / receiver surface) is in close contact with the outer surface of the pipe 7 as shown in FIG. The ultrasonic transmitter / receiver 20 functions as an ultrasonic transmitter in accordance with the drive signal supplied from the drive circuit 34. Specifically, the ultrasonic transmitter / receiver 100 generates a substantially impulse-like ultrasonic wave 100 as shown exaggeratedly in FIG. Fire periodically. Note that the emission period To of the ultrasonic wave 100 is appropriately determined mainly according to the outer diameter of the pipe 7, and is generally determined within the range of To = several tens [msec] to several hundreds [msec].

  Here, as shown in FIG. 4, it is assumed that the cooling water 8 is overflowing in the pipe 7, that is, the pipe 7 is filled with the cooling water 8. In this case, the ultrasonic wave 100 emitted from the ultrasonic transceiver 20 enters the side wall of the pipe 7 from the outer surface of the pipe 7. Then, the ultrasonic wave 100 entering the side wall of the pipe 7 propagates through the side wall and reaches the inner surface of the pipe 7. On the inner surface of the pipe 7, the acoustic impedance with respect to the propagation action of the ultrasonic wave 100 varies greatly due to the difference between the physical property of the side wall of the pipe 7 and the physical property of the cooling water 8. Therefore, most of the ultrasonic waves 100 that have reached the inner surface of the pipe 7 are reflected here, travel backward through the propagation path, and finally enter the ultrasonic transmitter / receiver 20 (ultrasonic transmitter / receiver surface).

  The ultrasonic transmitter / receiver 20 functions as an ultrasonic receiver every time an ultrasonic wave 100 is transmitted until the next ultrasonic wave 100 is transmitted, that is, receives a reflected wave (echo) of the ultrasonic wave 100. Then, this is converted into an electric signal 110. As shown in FIG. 5B, the converted electric signal, that is, the received signal 110, has a certain time corresponding to the wall thickness of the pipe 7 (side wall) from the time t0 when the ultrasonic wave 100 is emitted. At the time t1 when Ta has elapsed, a first reflected image 120 based on the ultrasonic wave 100 reflected by the inner surface of the pipe 7, that is, the first reflected wave appears.

  On the other hand, the remaining ultrasonic waves 100 that are not reflected by the inner surface of the pipe 7 enter the cooling water 8 overflowing in the pipe 7 as indicated by the white arrow 200 in FIG. Then, the ultrasonic wave 100 that has entered the cooling water 8 propagates through the cooling water 8 and reaches the inner surface on the opposite side (right side in FIG. 4) of the pipe 7, and is almost entirely formed by the inner surface on the opposite side. Reflected. The ultrasonic wave 100 substantially totally reflected by the inner surface on the opposite side, that is, the second reflected wave, also reverses the propagation path before being reflected as shown by an arrow 210 in FIG. It is incident on the sound wave transceiver 20.

  Accordingly, the second reflected wave is received in the received signal 110 shown in FIG. 5B from the time t1 when the first reflected image 120 appears to the time t2 when the time Tb corresponding to the inner diameter dimension of the pipe 7 has passed. A second reflected image 130 based on In general, the first reflected wave is larger than the second reflected wave. Therefore, the amplitude (peak-to-peak value) V1 of the first reflected image 120 is larger than the amplitude V2 of the second reflected image 130. Is also large (V1> V2). Naturally, the time Ta from the time t0 when the ultrasonic transmitter / receiver 20 emits the ultrasonic wave 100 to the time t1 when the first reflected image 120 appears in the received signal 110 by the ultrasonic transmitter / receiver 20 is constant. The time Tb from the time t1 when the first reflected image 120 appears in the received signal 110 to the time t2 when the second reflected image 130 appears is also constant.

  Next, as shown in FIG. 6A, a case where bubbles 9, 9,... Are generated in the pipe 7 (in the cooling water 8) will be considered. In this case, for the ultrasonic wave 100 propagating in the pipe 7 in the direction indicated by the arrow 200, these bubbles 9, 9,... Act as a kind of obstacle. When the ultrasonic wave 100 collides with any of the bubbles 9, the ultrasonic wave 100 is reflected by the bubble 9. The ultrasonic wave 100 reflected by the bubble 9, that is, the third reflected wave, also reverses the propagation path before being reflected as shown by an arrow 220 in the figure, and finally the ultrasonic transceiver 20. Is incident on. Furthermore, the generation of the third reflected wave reduces the ultrasonic wave 100 that reaches the inner surface of the pipe 7 on the side opposite to the side where the ultrasonic transceiver 20 is located (the right side in the figure). In other words, the second reflected wave (arrow 210) reflected by the opposite inner surface is reduced as indicated by arrow 210 in FIG.

  As a result, as shown in FIG. 6B, the third reflected image based on the third reflected wave is present between the first reflected image 120 and the second reflected image 130 of the received signal 110 by the ultrasonic transceiver 20. 140 appears. In addition, the amplitude V2 of the second reflected image 130 is reduced. The amplitude V1 of the first reflected image 120 does not change.

  Further, the larger the bubbles 9, 9,..., The larger the amplitude V3 of the third reflected image 140 is. On the other hand, the amplitude V2 of the second reflected image 130 becomes smaller. When the bubbles 9, 9,... Are extremely large (that is, when the bubbles 9, 9,... Are larger than the ultrasonic wave 200), the second reflected image 130 does not appear.

  Further, since the bubbles 9, 9,... Are always flowing, even if the bubbles 9, 9,... Are generated, when the ultrasonic wave 100 does not collide with the bubbles (in other words, the cycle), the third reflected image. 140 does not appear. Therefore, the greater the amount of bubbles 9, 9,..., The higher the frequency with which the third reflected image 140 appears. In addition, the time Tc from the time point t1 when the first reflected image 120 appears to the time point t3 when the third reflected image 140 appears is not constant between cycles and always varies.

  As described above, the received signal 110 that varies greatly depending on whether or not the bubbles 9, 9,... Are generated in the pipe 7 is input to the drive circuit 34 shown in FIG. The drive circuit 34 converts the input reception signal 110 into a digital signal, and the converted digital reception signal (hereinafter also referred to as the reception signal 110) is input to the CPU 36. The CPU 36 determines from the received signal 110 whether or not bubbles 9, 9,... Are generated in the pipe 7, and if the bubbles 9, 9,. Also determine thickness and quantity.

  Specifically, as shown in FIG. 7, the CPU 36 sets a threshold value Vd that is a criterion for determining whether or not the third reflected image 140 appears in the received signal 110. This threshold Vd is larger than the amplitude Vn of the noise component contained in the received signal 110, and the amplitude V2 of the second reflected image 130 when the bubbles 9, 9,... , Which is represented by the sign V2 ′) (Vn <Vd <V2 ′). The threshold value Vd may be automatically set by the CPU 36 according to the amplitude Vn of the noise component and the amplitude V2 ′ of the so-called normal second reflected image 130, or manually set by the operation key 38. May be.

  Then, the CPU 36 monitors the signal level in the predetermined period Td between the first reflected image 120 and the second reflected image 130 of the received signal 110, and obtains the maximum amplitude Vmax of the received signal 110 in the predetermined period Td. Then, the maximum amplitude Vmax is compared with the above-described threshold value Vd. When the maximum amplitude Vmax exceeds the threshold value Vd (Vmax> Vd), bubbles 9, 9,... Are generated in the pipe 7. , And if not, it is determined to be normal.

  In FIG. 7, the predetermined period Td is set from the time point t4 when the first reflected image 120 disappears to the time point t2 when the second reflected image 130 appears. Good. For example, a period from a time point slightly after the time point t4 when the first reflected image 120 disappears to a time point slightly before the time point t2 when the second reflected image 130 appears may be set as the predetermined period Td. Good.

  Further, when the CPU 36 determines that the bubbles 9, 9,... Are generated in the pipe 7, the CPU 36 also determines the size of the bubbles 9, 9,. . Specifically, a second threshold value Vd ′ (Vd ′> Vd) larger than the above-described threshold value Vd is set, and a third threshold value Vd ″ (Vd ″> Vd ′) that is larger than the second threshold value Vd ′. ) Is set. Then, the maximum amplitude Vmax is compared with these threshold values Vd, Vd ′, and Vd ″. Here, for example, the maximum amplitude Vmax is larger than the first threshold value Vd and equal to or less than the second threshold value Vd ′. When (Vd <Vmax ≦ Vd ′), it is determined that the bubbles 9, 9,... Are small in size, and the maximum amplitude Vmax is larger than the second threshold value Vd ′ and the third threshold value Vd. When “below” (Vd ′ <Vmax ≦ Vd ”), it is determined that the bubbles 9, 9,... Are medium size, and the maximum amplitude Vmax is larger than the third threshold value Vd” (Vmax> Vd ”). ), It is determined that the bubbles 9, 9,... Are large in size, and this size determination is not limited to three levels, large, medium and small, but may be two levels or four or more levels.

  The CPU 36 also determines the amount of bubbles 9, 9,... Generated in the pipe 7. Specifically, each time a predetermined number P of ultrasonic waves 100 are emitted from the ultrasonic transmitter / receiver 20, the number Q of times the maximum amplitude Vmax exceeds the threshold value Vd is counted. Then, a ratio R (= Q / P) of the count value Q to the number of times P of the ultrasonic wave 100 is obtained, and from this ratio R, the amount of bubbles 9, 9,. Judge by stage. The determination of the amount is not limited to three stages, and may be two stages or four or more stages. Further, it is determined that the bubbles 9, 9,... Are generated only when the amount of the bubbles 9, 9,. Also good.

  These determination results by the CPU 36 are displayed on the display 40. Specifically, as shown in FIG. 8, a lamp mark 300 indicating the presence or absence of bubbles 9, 9,... Is displayed on the upper left side of the screen of the display 40. This lamp mark 300 is displayed in green when bubbles 9, 9,... Are not generated, for example, and is displayed in red when bubbles 9, 9,. Therefore, the operator who handles the pipe internal state inspection apparatus 10 according to the first embodiment intuitively determines whether or not bubbles 9, 9,... Are generated in the pipe 9 from the display color of the lamp mark 300. Can be recognized.

  Then, another lamp mark 310 representing the size of the bubbles 9, 9,... Is displayed on the right side of the lamp mark 300 described above. The lamp mark 310 is displayed in yellow when the bubbles 9, 9,... Are small, for example, and is displayed in orange when the bubbles 9, 9,. When the bubbles 9, 9,... Are large in size, the lamp mark 310 is displayed in red. Therefore, the operator can intuitively recognize the size of the bubbles 9, 9,... From the display color of the lamp mark 310. When bubbles 9, 9,... Are not generated, the lamp mark 310 is displayed in green.

  Further, a lamp mark 320 representing the amount of bubbles 9, 9,... Is displayed on the right side of the lamp mark 310. The lamp mark 320 is displayed in yellow when the amount of bubbles 9, 9,... Is small, for example, and is displayed in orange when the amount of bubbles 9, 9,. When the amount of bubbles 9, 9,... Is large, the lamp mark 320 is displayed in red. Therefore, the operator can intuitively recognize the amount of bubbles 9, 9,... From the display color of the lamp mark 320. The lamp mark 320 is also displayed in green when bubbles 9, 9,... Are not generated.

  Then, below these lamp marks 300, 310 and 320, a waveform representing the received signal 110 is displayed in substantially real time. Therefore, the operator can determine the state in the pipe 7 also from the waveform 110. The time width (range) indicated on the horizontal axis of the display area 330 of the waveform 110 can be arbitrarily changed. Further, the gain width indicated on the vertical axis of the display area 330 can be arbitrarily changed.

  As described above, by using the pipe internal state inspection device 10 of the first embodiment, it is possible to inspect whether or not bubbles 9, 9,... Further, when the bubbles 9, 9,... Are generated, their sizes and amounts can also be known. This is extremely useful in operating a plant including the evaporative cooling device 1 shown in FIG. For example, if necessary, appropriate measures such as increasing the inner diameter of the pipe 7 or increasing the length of the pipe 7 can be taken.

  In the first embodiment, the maximum amplitude Vmax of the received signal 110 in the predetermined period Td shown in FIG. 7 is compared with the threshold value Vd, and bubbles 9, 9,... Although it has been determined whether or not it has occurred, this is not restrictive. For example, the absolute value of the signal level of the reception signal 110 in the predetermined period Td is obtained, and the maximum value of the absolute value is compared with an arbitrary threshold value, or the average value of the absolute value is compared with the arbitrary threshold value, The presence or absence of bubbles 9, 9,... May be determined from this comparison result. Of course, other determination methods may be used.

  Next, a second embodiment of the present invention will be described.

  In the above-described first embodiment, the signal level in the predetermined period Td between the first reflected image 120 and the second reflected image 130 of the received signal 110 is monitored, so that the bubbles 9, 9,. In the second embodiment, the presence or absence of the bubbles 9, 9,... Is determined by monitoring the amplitude V2 of the second reflected image 130.

  That is, as shown in FIG. 9, the CPU 36 sets a threshold value Vs to be compared with the amplitude V <b> 2 of the second reflected image 130. Similarly to the threshold value Vd in the first embodiment, this threshold value Vs is also larger than the amplitude Vn of the noise component included in the received signal 110 and smaller than the amplitude V2 ′ of the second reflected image 130 in the normal state. (Vn <Vs <V2 ′). Further, the threshold value Vs may be automatically set by the CPU 36 or may be manually set arbitrarily by the operation key 38. However, it is preferable that the threshold value Vs in the second embodiment is set larger (Vs> Vd) than the threshold value Vd in the first embodiment.

  Then, the CPU 36 monitors the amplitude V2 of the second reflected image 130. Specifically, the signal level of the received signal 110 is monitored over a predetermined period Ts from the time t2 when the second reflected image 130 appears. In FIG. 9, the predetermined period Ts is from the time t2 when the second reflected image 130 appears to the time when the second reflected image 130 disappears. However, an appropriate margin may be added to this. . For example, a period from the time t2 when the second reflected image 130 appears to a time slightly later than the time when the second reflected image 130 disappears may be set as the predetermined period Ts.

  The CPU 36 obtains the maximum amplitude Vmax ′ of the reception signal 110 in the predetermined period Ts, and regards the maximum amplitude Vmax ′ in the predetermined period Ts as the amplitude V2 of the second reflected image 130. Further, the CPU 36 compares the amplitude V2 (= Vmax ′) of the second reflected image 130 with the above-described threshold value Vs. When the amplitude V2 of the second reflected image 130 is smaller than the threshold Vs (V2 <Vs), it is determined that bubbles 9, 9,... Are generated in the pipe 7, and otherwise normal. It is determined that there is.

  When the CPU 36 determines that bubbles 9, 9,... Are generated in the pipe 7, the CPU 36 determines the size of the bubbles 9, 9,... Based on the amplitude V2 of the second reflected image 130. ,judge. Specifically, a second threshold value Vs ′ (Vs ′ <Vs) smaller than the above-described threshold value Vs is set, and a third threshold value Vs ″ (Vs ″ <Vs ′) that is smaller than the second threshold value Vs ′. ) Is set. Then, the amplitude V2 of the second reflected image 130 is compared with these threshold values Vs, Vs ′ and Vs ″. Here, for example, the amplitude V2 of the second reflected image 130 is more than the first threshold value Vs. When it is small and is equal to or larger than the second threshold value Vs ′ (Vs ′ ≦ V2 <Vs), it is determined that the bubbles 9, 9,... Are small in size, and the amplitude V2 of the second reflected image 130 is the first. Is smaller than the second threshold value Vs ′ and equal to or greater than the third threshold value Vs ″ (Vs ″ ≦ V2 <Vs ′), it is determined that the bubbles 9, 9,... When the amplitude V2 of 130 is smaller than the third threshold value Vs ″ (V2 <Vs ″), it is determined that the bubbles 9, 9,.

  In addition, the CPU 36 determines the amount of bubbles 9, 9,... Generated in the pipe 7 in three stages in the same manner as in the first embodiment. Then, the CPU 36 displays these determination results on the display 40 as shown in FIG.

  As described above, also according to the second embodiment, it is possible to inspect whether or not the bubbles 9, 9,... Are generated in the pipe 7, and the bubbles 9, 9,. Sometimes you can know their size and quantity.

  In the second embodiment, instead of the maximum amplitude Vmax ′ (V2) of the reception signal 110 in the predetermined period Ts shown in FIG. 9, the absolute value of the signal level of the reception signal 110 in the predetermined period Td is obtained. The absolute value may be compared with an arbitrary threshold value, or the average value of the absolute value may be compared with an arbitrary threshold value, and the presence / absence of bubbles 9, 9,. . Of course, other determination methods may be used.

  Next, a third embodiment of the present invention will be described.

  In the third embodiment, the maximum amplitude Vmax in the predetermined period Td between the first reflected image 120 and the second reflected image 130 of the received signal 110 described in the first embodiment and the second embodiment described. A ratio K (= Vmax / V2) of the amplitude V2 (= Vmax ′) of the second reflected image 130 is obtained, and the presence or absence of bubbles 9, 9,... Is determined based on this ratio K.

  That is, when there is no bubble 9, 9,... In the pipe 7, that is, when the third reflected image 140 does not appear in the received signal 110, the ratio K is substantially zero (K≈0). However, when bubbles 9, 9,... Are generated in the pipe 7 and the third reflected image 140 appears in the received signal 110, the ratio K increases. Therefore, the CPU 36 compares the ratio K with a predetermined threshold value, and determines the presence / absence of the bubbles 9, 9,... From the comparison result.

  When it is determined that bubbles 9, 9,... Are generated in the pipe 7, the CPU 36 performs the same procedure as in the first embodiment and the second embodiment, and the three different from the ratio K described above. .. Are compared with the threshold value, and the size of the bubbles 9, 9,... Further, the CPU 36 determines the amount of bubbles 9, 9,... In three stages in the same manner as in the first embodiment and the second embodiment. Then, these determination results are displayed on the display 40 as shown in FIG.

  In each of the above embodiments, the case where the pipe 7 is a so-called vertical pipe extending along the vertical direction has been described. However, the present invention is not limited to this. That is, the present invention can be applied even when the pipe 7 is a so-called horizontal pipe that extends along the horizontal direction or when it extends along the other direction. In addition, the pipe 7 is not limited to a circular pipe, but may have another shape such as an elliptical pipe or a square pipe.

  Furthermore, the present invention can also be applied to the inspection of the presence or absence of foreign matters other than the bubbles 9, 9,. And this invention can be applied not only to the plant containing the vaporization cooling device 1 but also to the steam plant mentioned above, for example, and also in the plant etc. which distribute | circulate oil, seawater, etc., the presence or absence of foreign materials, such as sand and gravel. The present invention can also be applied to inspection.

  Further, the display screen of the display 40 shown in FIG. 8 is merely an example until it gets tired, and is not limited to this. In particular, the presence or absence of the bubbles 9, 9,... Represented by the lamp mark 300 is not limited to visual information such as the lamp mark 300, but may be represented by auditory information such as an alarm sound. . Of course, the size and amount of the bubbles 9, 9,... Represented by the other lamp marks 310 and 320 may also be represented by similar auditory information.

  And you may combine each above-mentioned embodiment suitably. In this way, a more reliable inspection can be realized.

It is an illustration figure which shows an example of the plant in which this invention is used. It is an illustration figure which expands and shows a part in FIG. It is a block diagram which shows schematic structure of 1st Embodiment of this invention. It is an illustration figure which shows the use condition of the same embodiment. It is an illustration figure which shows the ultrasonic wave emitted from the ultrasonic transmitter-receiver in the same embodiment, and the received signal by the said ultrasonic transmitter-receiver. It is an illustration figure different from FIG. 4 which shows the use condition of the same embodiment. It is an illustration figure for demonstrating the basic principle of the embodiment. It is an illustration figure which shows the example of a display of the display in the same embodiment. It is an illustration figure for demonstrating the basic principle of 2nd Embodiment of this invention.

Explanation of symbols

7 Piping 8 Cooling water 9 Air bubbles 10 Piping internal state inspection device 20 Ultrasonic transmitter / receiver 30 Device body 36 CPU

Claims (8)

A transmission means that is in close contact with the outer surface of the pipe, which is usually in a state of fluid overflow, and transmits ultrasonic waves toward the inside of the pipe;
A receiving means for receiving the reflected wave of the ultrasonic wave provided in the vicinity of the transmitting means or integrally with the transmitting means;
Determining means for determining whether or not there is a foreign substance other than the fluid in the pipe based on a reception signal output from the receiving means;
A pipe internal state inspection device comprising: The received signal when the fluid is overflowing inside the pipe is a first reflected image by the ultrasonic wave being reflected by the inner surface of the pipe where the transmitting means is located; A second reflected image of the ultrasonic wave reflected by the inner surface of the pipe opposite to the side on which the transmitting means is located,
The determination unit performs determination based on a signal level in a predetermined period between the first reflected image and the second reflected image of the received signal.
The piping internal state inspection apparatus according to claim 1. The determination means also determines the size of the foreign matter based on the signal level of the reception signal in the predetermined period when it is determined that the foreign matter is present;
The piping internal state inspection apparatus according to claim 2. The received signal when the fluid is overflowing inside the pipe is a first reflected image by the ultrasonic wave being reflected by the inner surface of the pipe where the transmitting means is located; A second reflected image of the ultrasonic wave reflected by the inner surface of the pipe opposite to the side on which the transmitting means is located,
The determination means performs determination based on a signal level of the second reflected image;
The piping internal state inspection apparatus according to claim 1. The determination means also determines the size of the foreign matter based on the signal level of the second reflected image when it is determined that the foreign matter is present;
The pipe internal state inspection device according to claim 4. The transmission means transmits the ultrasonic wave substantially periodically,
The reception means receives the reflected wave every time the ultrasonic wave is transmitted from the transmission means,
The determination means determines each time the reflected wave is received by the reception means,
A frequency deriving unit that obtains a frequency at which the determination unit determines that the foreign object is present;
The piping internal state inspection apparatus according to any one of claims 1 to 5. The foreign matter is a bubble,
The pipe internal state inspection device according to any one of claims 1 to 6. A transmission process of transmitting ultrasonic waves from the transmission means in close contact with the outer surface of the pipe, which is usually in a state where the fluid is overflowing, toward the inside of the pipe;
A reception process of receiving the reflected wave of the ultrasonic wave by a reception unit provided in the vicinity of the transmission unit or integrally with the transmission unit;
A determination process for determining whether or not a foreign substance other than the fluid is present in the pipe based on a reception signal output from the reception unit;
A pipe internal state inspection method comprising:

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