JP2010276593A - Level measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem with conventional level measurement using the reflectance of an ultrasonic wave that the reliability of measurement drops depending on the surface state of a pipe to be measured. <P>SOLUTION: With ultrasonic wave transmitting and receiving means 11a, 11b, 11c, 12a, 12b, and 12c attached to a level measuring pipe 4, whether the point of reflection/transmission of an ultrasonic wave is a gas phase or a liquid phase is determined by specifying, from signals received by the ultrasonic wave transmitting and receiving means, the presence or absence of reflected waves from inner walls 4a and 4b of the level measuring pipe 4, transmitted waves from the ultrasonic wave transmitting and receiving means facing each other, and oblique transmitted waves from the ultrasonic wave transmitting and receiving means attached to positions of different heights on the opposite sides of the level measuring pipe 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system for measuring a liquid level of a vessel containing a liquid such as a reactor pressure vessel.

  In general, a differential pressure type water level gauge is used for measuring the reactor water level of a boiling water reactor, and high safety and reliability are ensured. In order to further improve the safety of the reactor, there is a method of measuring the reactor water level by a plurality of methods by providing a water level meter of a method different from the differential pressure type water level meter.

  As an example of a water level meter other than the differential pressure type, an ultrasonic water level meter is used (see, for example, Patent Document 1). The water level measurement by the conventional ultrasonic water level meter will be described with reference to FIG. FIG. 11 is an enlarged longitudinal sectional view of an ultrasonic probe attached to a liquid tank that is a water level measurement target and an enlarged view of the vicinity thereof.

  An ultrasonic transmission probe 101 a and an ultrasonic reception probe 101 b are attached to the surface of the liquid tank 100. The probes 101a and 101b are respectively arranged at different heights on the outer wall 102a of the liquid tank wall 102. When ultrasonic waves are transmitted from the probe 101 a to the inside of the liquid tank 100, the transmitted ultrasonic waves are propagated by being repeatedly reflected between the outer wall 102 a and the inner wall 102 b of the liquid tank wall 100 like the path 103 and the path 104. At this time, if the reflection point of the ultrasonic wave on the inner wall 102b is in the liquid phase, the reflectance of the ultrasonic wave is lower than that in the case where the reflection point is in the gas phase. Therefore, the ultrasonic wave is received by the probe 101b, the intensity of the ultrasonic wave transmitted by the probe 101a and the intensity of the ultrasonic wave received by the probe 101b are compared, and the reflection point is determined from the degree of decrease in intensity. It can be determined whether the gas phase. By such a principle, the water level can be measured. Then, by detecting not only the path 103 and the path 104 but also ultrasonic waves of a path that repeats more reflections, the water level can be determined using a large number of reflection points, and the water level can be measured finely. It becomes possible.

Japanese Patent No. 3732642

  The ultrasonic water level meter described above determines whether the reflection point is a liquid phase or a gas phase from a decrease in the reflectance of the ultrasonic wave at the reflection point on the inner wall of the liquid tank wall. However, the reflectivity of ultrasonic waves at the reflection points on the inner wall and outer wall of the liquid tank wall is also greatly influenced by the surface conditions of the inner wall and the outer wall. Therefore, there has been a problem that changes in the surface state due to environmental changes, deterioration over time, movement of reflection points, and the like affect the measurement accuracy of the water level.

  In general, equipment for monitoring the state of a nuclear reactor always has a demand for improvement in redundancy and measurement accuracy in order to improve its reliability.

  The present invention has been made to solve the above-mentioned problems, and is reliable even when the influence of the change in the surface state of the liquid tank wall caused by environmental changes, deterioration over time, movement of the launch point, etc. is large. The purpose is to provide a high liquid level measuring device.

  In order to achieve the above object, a liquid level measuring apparatus according to the present invention is attached to an outer wall of a pipe and transmits / receives ultrasonic waves to the ultrasonic transmission / reception means and ultrasonic transmission / reception means for transmitting / receiving ultrasonic waves. A control means for transmitting an instruction signal to be received, a reception means for receiving an ultrasonic reception signal of the ultrasonic transmission / reception means, and an ultrasonic wave received by the ultrasonic transmission / reception means based on the ultrasonic reception signal received by the reception means. Arithmetic means for determining whether a sound wave includes a transmitted wave reflected by the inner wall of the pipe on the side facing the ultrasonic transmission / reception means.

  The liquid level measuring device according to the present invention is attached to an outer wall of a pipe, and transmits and receives an ultrasonic wave transmitting / receiving means, and a second ultra-high wave attached to the pipe outer wall on the side facing the ultrasonic wave transmitting / receiving means. An ultrasonic wave transmitting / receiving means, a control means for transmitting an ultrasonic signal to the ultrasonic wave transmitting / receiving means into the pipe, a receiving means for receiving an ultrasonic wave reception signal of the second ultrasonic wave transmitting / receiving means, Based on the ultrasonic transmission / reception signal received by the reception unit, whether the ultrasonic wave received by the second ultrasonic transmission / reception unit includes a transmitted wave that is an ultrasonic wave transmitted from the ultrasonic transmission unit and transmitted through the pipe And calculating means for determining.

  The liquid level measuring device according to the present invention is attached to an outer wall of a pipe, and is attached to a position facing the first ultrasonic transmission / reception means across the pipe, and a first ultrasonic transmission / reception means for transmitting / receiving ultrasonic waves. Second ultrasonic transmission / reception means, third ultrasonic transmission / reception means attached to the first ultrasonic transmission / reception means at different positions in the pipe axis direction, and the third ultrasonic transmission / reception means across the pipe. Each of the fourth ultrasonic transmission / reception means, the first ultrasonic transmission / reception means, the second ultrasonic transmission / reception means, the third ultrasonic transmission / reception means, and the fourth ultrasonic transmission / reception means attached at opposite positions Each of control means for transmitting an instruction signal for transmitting ultrasonic waves into the pipe, each of the first ultrasonic transmission / reception means, the second ultrasonic transmission / reception means, the third ultrasonic transmission / reception means, and the fourth ultrasonic transmission / reception means of A receiving means for receiving a sound wave reception signal, and a first ultrasonic transmission / reception means, a second ultrasonic transmission / reception means, a third ultrasonic transmission / reception means, and a fourth ultrasonic transmission / reception means based on the ultrasonic reception signal. About each, the presence or absence of the reflected wave from the inner wall on the opposite side of the pipe, the presence or absence of the transmitted wave from the ultrasonic transmitting / receiving means at the opposite position, and the position attached to the outer wall on the opposite side of the pipe in the pipe axis direction Calculating means for determining the presence / absence of transmitted waves from ultrasonic wave receiving means different from each other.

  According to the liquid level measuring device of the present invention, the presence or absence of a reflected wave in the water level measuring tube is used to determine whether it is a liquid phase or a gas phase. High measurement is possible.

The longitudinal cross-sectional view which shows the outline of the water level measurement pipe | tube with which the liquid level measuring device by Example 1 is attached. The partial expanded longitudinal cross-sectional view of the water level measurement pipe | tube with which the liquid level measuring device by Example 1 was attached. FIG. 3 is a partially enlarged longitudinal sectional view of a water level measuring tube for explaining the operation of the liquid level measuring device according to the first embodiment. (A) The figure which showed the received signal in case a reflective point is a gaseous phase. (B) The figure which showed the received signal in case a reflective point is a liquid phase. FIG. 3 is a partially enlarged longitudinal sectional view of a water level measuring tube for explaining the operation of the liquid level measuring device according to the first embodiment. FIG. 3 is a partially enlarged longitudinal sectional view of a water level measuring tube for explaining the operation of the liquid level measuring device according to the first embodiment. The partial expanded longitudinal cross-sectional view of the water level measurement pipe | tube with which the liquid level measuring device by Example 2 was attached. (A) The front view of the reflecting plate 24, (b) AA arrow sectional drawing shown to Fig.8 (a). The partial expanded longitudinal cross-sectional view of the water level measurement pipe | tube with which the liquid level measuring device by Example 3 was attached. The cross-sectional view of the hydrogen measuring tube with which the liquid level measuring device by Example 4 was attached. The figure which shows the conventional liquid level measuring apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view schematically showing a water level measuring tube of a reactor pressure vessel to which a liquid level measuring device according to this embodiment is attached. As shown in FIG. 1, an upper pipe 2 and a lower pipe 3 for measuring the water level of a pressure vessel and a water level measurement for connecting the upper pipe 2 and the lower pipe 3 to a reactor pressure vessel 1 of a boiling water reactor. A tube 4 is provided. A plurality of ultrasonic transmission / reception means 11 and 12 are attached to the side surface of the water level measurement tube 4. Further, water as a coolant is injected into the reactor pressure vessel 1.

  The configuration of the liquid level measuring device according to the present invention will be described with reference to FIG. FIG. 2 is an enlarged vertical cross-sectional view of an enlarged water level measuring tube to which the liquid level measuring device according to this embodiment is attached. Ultrasonic transmission / reception means 11 a, 11 b, 11 c are attached to the side surface of the water level measuring tube 4 side by side in the axial direction of the water level measuring tube 4. Further, ultrasonic transmission / reception means 12a, 12b, 12c are attached to the surface of the side of the water level measurement tube 4 opposite to the ultrasonic transmission / reception means 11a, 11b, 11c. The ultrasonic transmission / reception means 11a, 11b, 11c and the ultrasonic transmission / reception means 12a, 12b, 12c are arranged so as to face each other with the water level measurement tube 4 interposed therebetween.

  These ultrasonic transmission / reception means 11 a, 11 b, 11 c, 12 a, 12 b, 12 c transmit ultrasonic pulses to the inside of the water level measurement tube 4, and the transmitted ultrasonic pulses are the inner wall 4 a of the water level measurement tube 4 and the inner wall on the opposite side. The reflected wave reflected at 4b is received. Further, the ultrasonic transmission / reception means 11 a, 11 b, 11 c, 12 a, 12 b, 12 c receive the transmitted wave of the ultrasonic pulse transmitted from the opposing ultrasonic transmission / reception means and transmitted through the water level measurement tube 4. For example, the ultrasonic transmission / reception unit 11a receives a reflected wave reflected by the inner wall 4a and the inner wall 4b of the ultrasonic pulse transmitted by the ultrasonic transmission / reception unit 11a, and transmits a transmitted wave of the ultrasonic pulse transmitted by the ultrasonic transmission / reception unit 12a. Receive. In FIG. 2, only three pairs of ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are shown. However, the number of ultrasonic transmission / reception means is not limited, and a larger number of ultrasonic transmission / reception means should be installed. Is possible. For example, since the installation interval in the axial direction of the ultrasonic transmission / reception means represents the measurement accuracy of the water level, and the number of installations in the axial direction represents the measurement range of the water level, the number of ultrasonic transmission / reception means is determined from the measurement accuracy of the water level and the measurement range. It is also possible to decide. As another example, the number of ultrasonic transmission / reception means can be determined from the number of water level lines set in the water level measuring tube 4. Further, there is a method in which only one ultrasonic transmission / reception unit is installed above and below the current water level.

  The ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are connected to the control means 21 that transmits an electrical signal to each ultrasonic transmission / reception means and receives an electrical signal from each ultrasonic transmission / reception means. Yes. Further, a modulation means 22 is installed between each ultrasonic transmission / reception means and the control means 21. The modulation means 22 modulates and transmits the amplitude intensity, the time width, and the number of cycles for the electrical signal transmitted from the control means 21 to each ultrasonic transmission / reception means. The control means 21 is connected to a water level calculation means 23 that determines whether the water level measuring tube 4 is in a gas phase or a liquid phase based on a signal received by the control means 21 from each ultrasonic transmission / reception means.

  The electrical signal that the control means 21 transmits to each ultrasonic transmission / reception means is a signal that instructs each ultrasonic transmission / reception means to transmit ultrasonic waves (hereinafter referred to as an instruction signal). The electrical signal received by the control means 21 from each ultrasonic transmission / reception means is a signal (hereinafter referred to as a reception signal) that is emitted when each ultrasonic transmission / reception means receives an ultrasonic wave.

  These control means 21, modulation means 22, and water level calculation means 23 are installed outside the reactor containment vessel such as the central control room of the nuclear power plant or outside the management area. The control means 21, the modulation means 22, the water level calculation means 23, and each ultrasonic transmission / reception means are electrically connected via the containment vessel penetration pipe and transmit / receive electrical signals.

  The upper pipe 2, the lower pipe 3, and the water level measuring pipe 4 are made of a material such as stainless steel, nickel base alloy, low alloy steel, carbon steel, or the like. Further, the total length of the water level measuring tube 4 is determined based on a desired range for measuring the water level. There is no designation for the inner diameter of the water level measuring tube 4, and it may be of any size. In addition, the outer diameter of the water level measuring tube 4 is set so as to have a thickness that does not cause damage or breakage even under high temperature and high pressure conditions assumed in an abnormal state. The upper pipe 2 and the lower pipe 3 are not specified for the outer diameter, inner diameter, and length. Further, the upper pipe 2 and the lower pipe 3 are inclined so that non-condensable gas does not accumulate inside. In the present embodiment, the cross-sectional shapes of the water level measuring pipe 4, the upper pipe 2 and the lower pipe 3 are all circular, but the inner and outer surfaces can be elliptical or polygonal. Specifically, for example, the cross-sectional shape of the inner surface can be a circle, and the outer surface can be a regular hexagon. Moreover, the cross-sectional shapes of the inner and outer surfaces of the water level measurement pipe 4, the upper pipe 2, and the lower pipe 3 can be changed depending on the location. For example, a circular water level measuring tube 4 is used, and the outer surface of the part to which the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, 12c is attached is polygonal, and the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b , 12c can be attached to a polygonal plane.

  The ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are ultrasonic probes composed of vibrators having heat resistance and release resistance such as lithium niobate. Each ultrasonic transmission / reception means is attached to the side surface of the water level measuring tube 4 using a metal or liquid co-plant. The frequency of the ultrasonic pulse is set in the range of several hundred KHz to several hundred MHz so as to propagate through the water level measuring tube 4 and the liquid phase. As the ultrasonic probe, individual vibrators may be arranged, or arranged vibrators such as a phase array sensor may be used.

  The control means 21 is a high voltage generation circuit for generating instruction signals for the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, 12c, and the reception signals of the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, 12c. It consists of a voltage amplification circuit to detect.

  The modulation means 22 is a voltage modulation circuit that is connected to the high voltage generation circuit of the control means 21 and outputs a pulse by changing the voltage, time width, and cycle number of the electric signal. The ultrasonic pulses transmitted from the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are determined by the voltage of the instruction signal and the like. Therefore, the modulation means 22 modulates the instruction signal, whereby the ultrasonic pulses transmitted from the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are modulated. The modulation unit 22 can individually modulate the instruction signal transmitted to each ultrasonic transmission / reception unit. Accordingly, the frequency and amplitude of the ultrasonic pulse emitted from each of the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c can be different for each ultrasonic transmission / reception means.

  The water level calculation means 23 performs a calculation based on the reception signal detected by the voltage amplification circuit of the control means 21, and specifies the presence or absence of a reflected wave or a transmitted wave in the ultrasonic wave received by each ultrasonic transmission / reception means, It is determined whether the water level measuring tube 4 is in a gas phase or a liquid phase. For example, the received signal of the ultrasonic transmission / reception unit 11a is processed, and the ultrasonic wave received by the ultrasonic transmission / reception unit 11a is a reflected wave transmitted from the ultrasonic transmission / reception unit 11a and reflected by the inner wall 4a or the inner wall 4b. The transmission / reception means 12a determines whether the transmitted wave is transmitted through the water level measuring tube 4. If there is a lot of noise in the received signal, the presence or absence of reflected or transmitted waves should be checked after performing noise removal and waveform extraction as preprocessing by analog or digital filter circuits or frequency filtering processing by software. Identify.

  The ultrasonic pulse causes multiple reflection and mode conversion in the tube wall of the water level measurement tube 4 and in the internal liquid phase of the water level measurement tube 4. The ultrasonic pulse is determined using the reflected wave and transmitted wave that have been subjected to multiple reflection and mode conversion. You can also In the present embodiment, description will be made assuming that a reflected wave or transmitted wave without multiple reflection or mode conversion is used.

  As the water level calculation means 23, a calculation program may be incorporated into a general personal computer, or dedicated hardware may be manufactured.

  Next, the operation of the liquid level measuring device according to the present embodiment will be specifically described. First, water level measurement using reflected waves on the inner wall 4a and the inner wall 4b using the ultrasonic transmission / reception means 11a will be described with reference to FIG. FIG. 3 is an enlarged view of FIG. 2, and illustrates the ultrasonic pulse transmitted from the ultrasonic transmission / reception means 11a and the path of the reflected wave. Moreover, the water level is different between FIG. 3 (a) and FIG. 3 (b). Some components are not shown.

  The instruction signal of the control means 21 is modulated by the modulation means 22 and transmitted to the ultrasonic transmission / reception means 12b, and the ultrasonic reception means 11a transmits an ultrasonic pulse 31a to the water level measurement tube 4.

  As shown in FIG. 3A, when the reflection point of the ultrasonic pulse 31a is a gas phase inside the water level measuring tube 4, the ultrasonic pulse 31a does not pass through the inner wall 4a, and the ultrasonic transmission / reception means 11a. Receives the reflected wave 31b from the inner wall 4a. The reflection point means a position where the ultrasonic pulse 31 a is reflected by the inner wall of the water level measurement tube 4.

  As shown in FIG. 3B, when the reflection point of the ultrasonic pulse 31a on the inner wall 4a is in the liquid phase inside the water level measuring tube 4, a part of the ultrasonic pulse 31a is reflected by the inner wall 4a, and a part is The light passes through the inner wall 4a and enters the liquid phase. The ultrasonic pulse 31a entering the liquid phase reaches the inner wall 4b and is reflected. The ultrasonic transmission / reception means 11a receives the reflection 31b from the inner wall 4a and the reflected wave 31c from the inner wall 4b.

  The water level calculation means 23 calculates the reception signal received by the control means 21 from the ultrasonic transmission / reception means 11a, and specifies whether the reflected waves 31b and 31c are included in the ultrasonic waves received by the ultrasonic transmission / reception means 11a. . Specifically, first, the received signal is subjected to frequency filtering to remove noise. Next, the reflected wave 31b and the reflected wave 31c are specified based on the modulation state and observation time of the ultrasonic pulse. Since the ultrasonic pulse is modulated for each ultrasonic transmission / reception means, it is possible to determine from which ultrasonic transmission / reception means the reflected wave is caused by the ultrasonic pulse transmitted from the ultrasonic frequency or the like. The reflected wave 31b and the reflected wave 31c have different path lengths from when they are transmitted from the ultrasonic transmission / reception means 11a to when they are received by the ultrasonic transmission / reception means 11b. Therefore, the reflected wave 31c is received after the reflected wave 31b. The Therefore, the reflected wave 31b and the reflected wave 31c can be specified from the modulation state and observation time of the ultrasonic pulse.

  An example of such a received signal is shown in FIG. 4A shows a reception signal when the reflection point is in the gas phase and only the reflected wave 31b exists, and FIG. 4B shows a reception signal where the reflection point is in the liquid phase and the reflection waves 31b and 31c exist. Is shown. 4 (a) and 4 (b), the vertical axis represents the amplitude intensity of the signal, and the horizontal axis represents time.

  When the reflection point is a gas phase, an amplitude indicating reception of an ultrasonic wave appears only once as shown in FIG. On the other hand, in FIG. 4B, an amplitude indicating reception of an ultrasonic wave appears twice. The reflected wave 31b appears first, and the reflected wave 31c appears later. Further, the signal appearing in other parts is noise. In FIG. 4B, it can be seen that the amplitude due to reception of the reflected wave 31b is smaller than in FIG.

  Next, a threshold value is set for the amplitude of the received signal, and a binary determination is made that an ultrasonic wave has been received if the waveform amplitude is greater than the threshold value, and no ultrasonic wave has been received if the waveform amplitude is less than the threshold value. The threshold value is set to an appropriate value so that the received signal when the reflected wave is received can be appropriately determined as the received signal without receiving noise as the received signal. In other words, the value is set such that the noise does not exceed the threshold and the received signal of the reflected wave exceeds the threshold. As a result of the binary determination, when the reflected wave 31c does not exist, it is determined that the reflection point is a gas phase. Moreover, when the reflected wave 31c exists as a result of binary determination, it determines with a reflective point being a liquid phase. Regarding the setting of the threshold value, when the amplitude of the reflected wave 31b when the reflection point is in the liquid phase is smaller than the signal of the reflected wave 31c as shown in FIG. 4B, the reflected wave when the reflection point is in the liquid phase. The threshold may be higher than the amplitude of 31b. This is because it is important to determine the presence or absence of the reflected wave 31c, and it is sufficient if the amplitude of the reflected wave 31c exceeds the threshold value.

  By performing such binary determination, it is possible to avoid misidentifying weak signals caused by noise and other ultrasonic waves as the reflected waves 31b and 31c.

Further, as a determination method different from the above-described binary determination, the determination can be made by comparing the reception signals of the reflected wave 31b and the reflected wave 31c. Specifically, the amplitude of the received signal of the reflected wave 31b is Ua, the amplitude of the received signal of the reflected wave 31c is U'a, and the amplitude ratio V of the signal is obtained by the following equation (1).

  Further, the threshold value is set for the obtained amplitude ratio V, and binary determination is performed. When V = 0, the reflection point is determined as the gas phase, and when V = 1, the reflection point is determined as the liquid phase. The determination using the amplitude ratio of the received signal can be used in combination with the above-described method for determining the presence or absence of the reflected wave 31b and the reflected wave 31c, and using a plurality of determination indexes can increase the reliability of measurement. it can.

  In this way, it is possible to determine whether the reflection point is the liquid phase or the gas phase by specifying whether the ultrasonic wave transmitting / receiving means 11a has received the reflected wave from the inner wall 4a and the opposite inner wall 4b. . Since the ultrasonic reflectivity is not used, when the inner wall surface of the water level measuring tube 4 has irregularities as in the conventional method, the influence of the inner wall surface state is small, and determination with high reliability is possible.

  The determination using the reflected wave described above can be performed by a single ultrasonic transmission / reception means. Further, instead of the reflected wave 31c, it is also possible to use a reflected wave that is transmitted through the inner wall 4b and reflected by the outer surface of the water level measuring tube 4.

  As for the ultrasonic transmission / reception means 12a, 12b, and 12c, if the reflected wave on the outer surface of the water level measuring tube 4 is not received through the inner wall 4a or the inner wall 4a as a result of the calculation processing of the water level calculation means 23, If the phase is received, it is determined as the liquid phase.

  Finally, the water level calculation means 23 makes a determination on each of the ultrasonic receiving means attached in the axial direction of the water level measuring tube 4 and measures the water level using the result. For example, when the ultrasonic transmission / reception means 11a, 12a obtains a determination result that is in the gas phase and the ultrasonic transmission / reception means 11b, 11c, 12b, 12c are in the liquid phase, the water level is ultrasonic transmission / reception with the ultrasonic transmission / reception means 11a. Between the means 11b. Therefore, as the number of ultrasonic transmission / reception means is increased in the axial direction, the water level can be measured with higher accuracy. That is, the installation interval in the axial direction of the ultrasonic transmission / reception means represents the measurement accuracy of the water level, and the number of installations represents the measurement range. Moreover, when the ultrasonic transmission / reception means 11a, 11b, 11c, 12a, 12b, and 12c are installed in accordance with the water level line set in the water level measuring tube 4 according to the purpose, the liquid level for detecting the set water level. It becomes a measurement method. Furthermore, when the ultrasonic transmission / reception means 11a, 11b, 12a, and 12b are installed above and below the water level, the liquid level measurement method detects whether or not the water level has changed. The detection accuracy of the presence or absence of water level fluctuation is the installation interval in the axial direction of the ultrasonic transmission / reception means 11a, 11b, 12a, 12b.

  Next, water level measurement using transmitted waves from the opposing ultrasonic transmission / reception means will be described using the ultrasonic transmission / reception means 11a and 12a. FIG. 5A is a further enlarged view of FIG. 2, and illustrates the path of an ultrasonic pulse transmitted from the ultrasonic transmission / reception means 11a. Moreover, the water level is different between FIG. 5 (a) and FIG. 5 (b). Some components are not shown.

  The ultrasonic transmission / reception means 11 a transmits an ultrasonic pulse 31 a to the water level measurement tube 4. In particular, when the ultrasonic transmission / reception means 11a is a phase array sensor, the transmission angle of the ultrasonic pulse 31a can be controlled by controlling the phase of each sensor of the phase array sensor.

  As shown in FIG. 5A, when the transmission point of the ultrasonic pulse 31a on the inner wall 4a is a gas phase, the ultrasonic pulse 31a does not pass through the inner wall 4a and does not reach the ultrasonic transmission / reception means 12a. The transmission point means a position where the ultrasonic pulse 31 a passes through the inner wall of the water level measurement tube 4. It means substantially the same position as the reflection point described above.

  On the other hand, as shown in FIG. 5B, when the transmission point of the ultrasonic pulse 31a on the inner wall 4a is in the liquid phase, a part of the ultrasonic pulse 31a passes through the inner wall 4a and the inner wall 4b to transmit the ultrasonic transmission / reception means 12a. To reach. The ultrasonic pulse reaching the ultrasonic transmission / reception means 12a from the ultrasonic transmission / reception means 11a is defined as a transmitted wave 31d. The reflected waves of the ultrasonic pulse reflected by the inner wall 4a and the inner wall 4b are not shown in FIG. 5B.

  The water level calculation means 23 specifies the presence or absence of the transmitted wave 31d from the signal received by the control means 21 from the ultrasonic transmission / reception means 12a. Specifically, noise is removed from the received signal by frequency filtering, and the transmitted wave 31d is specified from the modulation state and observation time of the ultrasonic pulse.

  In the above-described determination using the reflected wave, the reflected waves from the inner wall 4a and the inner wall 4b received by the ultrasonic transmission / reception means 11a are both caused by the ultrasonic pulses transmitted by the ultrasonic transmission / reception means 11a. However, in the case of the determination using the transmitted wave, only the transmitted wave 31d is the ultrasonic wave that reaches the ultrasonic transmission / reception unit 12a due to the ultrasonic pulse transmitted from the ultrasonic transmission / reception unit 11a. Moreover, since the diameter of the water level measuring tube 4 is known, it is possible to estimate the time from when the ultrasonic transmission / reception means 12a transmits the ultrasonic pulse until the ultrasonic transmission / reception means 11a observes the transmitted wave 31d. is there. Therefore, the transmitted wave 31d can be specified only by the modulation state or the observation time. Furthermore, it is possible to reliably specify the transmitted wave 31d by using the modulation state and the estimated observation time together.

  Next, a threshold value for binary determination is set for the amplitude of the received signal. If the transmitted wave 31d exists as a result of the binary determination, the transmission point is determined as the liquid phase. On the other hand, if there is no transmitted wave 31d, the transmission point is determined to be the gas phase.

  Further, as a determination method different from the above-described binary determination, the amplitude of the received signal of the transmitted wave 31d is set as U ″ a, and the amplitude ratio V ′ with Ua is obtained to perform the binary determination, and V ′ = 0. In this case, the permeation point can be determined as the gas phase, and conversely, when V ′ = 1, the permeation point can be determined as the liquid phase.

  In this way, by using the determination using the transmitted wave from the opposing ultrasonic transmission / reception means in combination with the determination using the reflected wave, it is possible to obtain a larger number of determination indexes and increase the reliability of the determination. Is possible.

  The above-described determination using transmitted waves can be performed for each pair of ultrasonic transmission / reception means paired. Further, it can be performed for each of the pair of ultrasonic transmission / reception means. That is, for example, in addition to the presence / absence of the transmitted wave from the ultrasonic transmission / reception unit 12a, the presence / absence of the transmitted wave from the ultrasonic transmission / reception unit 11a can be specified and determined. That is, two determination indexes can be obtained by a pair of ultrasonic transmission / reception means.

  In addition, when the determination method using the reflected wave described above and the determination method using the transmitted wave are used in combination, whether the reflection point / transmission point is the liquid phase or the gas phase is determined based on the waveform amplitude of the reflection wave and the transmission wave, as described above. A determination result by a total of four methods of determination by V and V ′ is obtained. For these determination results, select and determine the highest-priority determination, weight each determination, determine a number of determination results, classify determination using a neural network such as a support vector machine, etc. A final determination is made as to whether it is a gas phase or a liquid phase by the method.

  Next, water level measurement using oblique transmission waves will be described using the ultrasonic transmission / reception means 11a and 12b. FIG. 6 is an enlarged view of FIG. 2 and illustrates an ultrasonic pulse emitted from the ultrasonic transmission / reception means 11a. Moreover, the water level is different between FIG. 6 (a) and FIG. 6 (b). Some components are not shown.

  The ultrasonic transmission / reception means 11 a transmits an ultrasonic pulse 31 a to the water level measurement tube 4. As shown in FIG. 6A, when the reflection point on the inner wall 4a of the ultrasonic pulse 31a is a gas phase, the ultrasonic pulse 31a does not pass through the inner wall 4a and does not reach the ultrasonic transmission / reception means 12b.

  On the other hand, as shown in FIG. 6B, when the reflection point on the inner wall 4a of the ultrasonic pulse 31a is in the liquid phase, a part of the ultrasonic pulse 31a passes through the inner wall 4a and the inner wall 4b and enters the liquid phase. The ultrasonic transmission / reception means 12b is reached. This oblique transmission wave is 31e. The water level calculation means 23 specifies the oblique transmission wave 31e from the signal received by the control means 21 from the ultrasonic transmission / reception means 12b.

  Specifically, it is the same as the determination on the transmitted wave of the ultrasonic transmission / reception means 11a and 12a described above. First, noise is removed from the received signal by frequency filtering processing, and the oblique angle is calculated from the modulation state and observation time of the ultrasonic pulse. The transmitted wave 31e is specified. As in the case of the transmitted wave 31d described above, the oblique transmitted wave 31e can be specified only by either the modulation state or the observation time, but the oblique transmitted wave can be more reliably used by using the modulation state and the observation time together. It is possible to specify 31e. Next, a threshold value for binary determination is set to the amplitude of the oblique transmission wave. If the oblique transmission wave 31e exists as a result of the binary determination, the reflection point / transmission point is determined as the liquid phase. On the contrary, when the oblique transmission wave 31e does not exist, the transmission point and the reflection point are determined as the gas phase.

  When the determination using the oblique transmission wave is performed, the transmission points of the oblique transmission wave on the inner walls 4a and 4b are different from the reflection waves 31b and 31c and the transmission wave 31d described above. In the determination using the above-described reflected wave or transmitted wave, the reflection point / transmission point is located at the height at which each ultrasonic transmission / reception means is attached. However, in the case of determination using oblique transmission waves, the reflection point / transmission point is located at an intermediate height between a set of ultrasonic transmission / reception means used for determination. Therefore, even if the influence of the surface state at the reflection point / transmission point of the reflected wave or transmitted wave of the inner walls 4a and 4b is large, the oblique transmitted wave can be determined without being influenced by the surface state.

  Further, as described above, the oblique angle transmitted wave can be determined about the intermediate height of a set of ultrasonic transmission / reception means. Therefore, it is possible to determine the height different from the mounting height of the ultrasonic transmission / reception means. In the above-described embodiments, the ultrasonic transmission / reception means 11a and 12b are used. However, for example, the ultrasonic transmission / reception means 11a and 12c are used. . Therefore, it is possible to determine a number of height positions by combining ultrasonic transmission / reception means. As shown in FIG. 2, when three pairs of ultrasonic transmission / reception means are provided, determinations can be made in six combinations and in both directions, so that determination results using a total of 12 oblique transmitted waves can be obtained.

  As described above, according to the liquid level measuring device of the present embodiment, the water level is determined by using the reflected wave of the ultrasonic pulse from the inner wall in the water level instrumentation tube and the inner wall on the opposite side to determine whether the liquid level or the gas phase. Therefore, the water level can be measured with high reliability without being affected by the change in the surface state of the liquid tank wall.

  In addition, for a pair of ultrasonic transmission / reception means, the transmitted wave from the opposing ultrasonic transmission / reception means is used to determine whether it is a liquid phase or a gas phase, and the water level is obtained. The water level can be measured with high reliability.

  Further, in the determination using the oblique transmission wave, it is possible to determine a height different from the height at which the ultrasonic transmission / reception means is attached, and it is possible to measure the water level with high accuracy.

  In the determination using the oblique transmitted wave, a large number of determination results corresponding to the combination of the ultrasonic transmission / reception means can be obtained, and the water level measurement with high reliability is possible.

  Further, determination using these reflected waves / transmitted waves / obliquely transmitted waves can be used in combination, and water level measurement with high reliability can be performed by redundant and multiplexed determination. Further, the water level can be measured even when some ultrasonic transmission / reception means are broken or when the sensitivity is lowered.

  Further, by individually modulating the ultrasonic pulse transmitted by each ultrasonic transmission / reception means, it is possible to identify which ultrasonic transmission / reception means the received reflected wave / transmitted wave / oblique transmitted wave is transmitted from. It is possible to measure the water level with high accuracy by installing the transmitting / receiving means in close proximity, to measure the water level using a large number of ultrasonic transmitting / receiving means, and to measure the water level with high reliability using transmitted waves and oblique transmitted waves.

  Moreover, since the transmission / reception means, the modulation means, and the water level calculation means can be installed outside the reactor containment vessel such as outside the central control room or the management area, it is possible to measure the water level without fear of failure.

  In the present embodiment, description will be made assuming that three pairs of ultrasonic transmission / reception means are used. However, as described above, there are no restrictions on the quantity or the installation interval. Further, by moving the ultrasonic transmission / reception means up and down, that is, by scanning the ultrasonic transmission / reception means, it is possible to measure the water level with a small number (for example, one) of ultrasonic transmission / reception means. By making a single ultrasonic transmission / reception means scan in the axial direction of the water level measurement tube 4 and making a determination a plurality of times, the single ultrasonic transmission / reception means can measure the water level with high accuracy. The scanning of the ultrasonic transmission / reception means is performed by moving it up and down away from the water level measurement tube 4 using, for example, a robot arm, or bringing it into contact again, or while keeping the ultrasonic scanning means in contact with the water level measurement tube 4 using a ball screw or the like. This is done by moving it up and down.

  Moreover, it is also possible to use together the ultrasonic transmission / reception means fixed to the water level measurement tube 4 and the ultrasonic transmission / reception means attached so that the water level measurement tube 4 can be scanned in the axial direction.

  A second embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as Example 1, and the overlapping description is abbreviate | omitted. FIG. 7 shows an enlarged view of the water level measuring tube to which the liquid level measuring device according to this embodiment is attached.

  In this embodiment, ultrasonic transmission / reception means 11 a, 11 b, 11 c are attached to the water level measurement tube 4. Further, a reflector 24 is attached to the inner wall 4 b of the water level measuring tube 4. The reflection plate 24 is a reflection unit that reflects ultrasonic pulses from the ultrasonic transmission / reception units 11a, 11b, and 11c, and has a higher ultrasonic reflectance than the pipe inner wall 4b. An ultrasonic transmission / reception means 13 is attached to the lower end of the water level measurement tube 4. The ultrasonic transmission / reception means 13 is connected to the control means 21 and the second control means 25 installed separately. The second control means 25 is connected to the second water level calculation means 26. Further, a sound speed calculation means 27 connected to the control means 21 and the second control means 25 is provided.

  The reflector 24 is made of a material such as stainless steel, nickel-base alloy, low alloy steel, carbon steel, etc., similar to the water level measuring tube 4. As the shape, a flat plate having a plane parallel to the axial direction of the water level measuring tube 4 is used so as to regularly reflect the ultrasonic pulse. The reflector 24 is attached to the inner wall 4b by welding. Moreover, you may use as a shape which hollowed the cone and the polygonal pyramid from this flat plate. An example in which a cone is cut out from a flat plate and used as the reflector 24 is shown in FIG. 8A is a front view of the reflecting plate 24, and FIG. 8B is a cross-sectional view taken along line AA shown in FIG. 8A. The concave portion 24a hollowed out in a conical shape preferably has a conical bottom area of the same size as the transmission / reception surfaces of the ultrasonic transmission / reception means 11a, 11b, 11c. Further, the inner wall surface of the water level measuring tube 4 can be polished to be a reflecting means, the inner wall can be processed into a flat surface to be a reflecting means, or a conical or polygonal pyramid can be directly cut from the inner wall to be a reflecting means.

  In the present embodiment, the following description will be made assuming that a flat plate that is long in the axial direction of the water level measuring tube 4 is used as the reflecting plate 24.

  The ultrasonic transmission / reception means 13 is composed of a heat-resistant and release-resistant vibrator such as lithium niobate, similar to the ultrasonic transmission / reception means 11a, 11b, 11c, and the water level measuring tube 4 using a metal or liquid coplant. It is attached to the lower end surface. The frequency of the ultrasonic pulse is set in the range of several hundred kHz to several hundred MHz so as to propagate through the water level measurement tube 4 and the liquid phase.

  Similarly to the control means 21, the second control means 25 is a high voltage generation circuit that generates an electrical signal for generating an ultrasonic pulse in the ultrasonic transmission / reception means 13, and an electric power generated by the ultrasonic pulses received in the ultrasonic transmission / reception means 13. It consists of a voltage amplifier circuit that detects signals.

  The second control means 25, the second water level calculation device 26, and the sonic speed calculation means 27 are installed outside the reactor containment vessel outside the central control room of the nuclear power plant and outside the management area, like the control means 21 and the like. The ultrasonic transmission / reception means 13 and the like are connected through the containment vessel penetration pipe.

  The second water level calculation means 26 identifies the reflected wave reflected by the liquid level 5 inside the water level measurement tube 4 from the electrical signal detected by the second control means 25. That is, the ultrasonic wave transmission / reception means 13 transmits the signal into the water level measurement tube 4 and the reflected wave reflected by the liquid surface 5 and received by the ultrasonic wave transmission / reception means 13 is specified.

  The specification of the reflected wave is performed by binary determination by setting a threshold value for the amplitude of the electric signal, similarly to the specification of the reflected wave and the transmitted wave described in the first embodiment. If the detected electrical signal is noisy, noise removal and waveform extraction are performed as preprocessing by frequency filtering processing using an analog or digital filter circuit or software to detect a reflected wave from the liquid surface.

  The sound speed calculating means 27 is an electric signal detected by the voltage amplification circuit of the control means 21, that is, an inner wall of the water level measuring tube 4 from the received signals when the ultrasonic transmitting / receiving means 11a, 11b, 11c receive the ultrasonic waves. The reflected wave at 4a and the reflected wave from the reflecting plate 24 attached to the inner wall 4b on the opposite side are specified. The identification is performed by binary determination in which a threshold is set for the amplitude of the electric signal, as in the first embodiment.

Furthermore, the sound speed calculation means 27 obtains an observation time difference Δt between the reflected wave from the inner wall 4a and the reflected wave from the reflecting plate 24, and uses the known interval between the inner wall 4a and the reflecting plate 24 to obtain the following equation (2). Is used to obtain the sound velocity v of the ultrasonic pulse.

  In addition, since the reflected wave causes multiple reflection and mode conversion on the pipe wall of the water level measurement tube 4 and the internal liquid phase, the reflected wave is obtained by multiple reflection or mode conversion of the presence or absence of the reflected wave and the sound velocity v of the ultrasonic pulse. It can also be obtained using.

  Next, the operation of the liquid level measuring apparatus according to this embodiment will be described. About the ultrasonic transmission / reception means 11a, 11b, 11c, the point which determines whether it is a liquid phase or a gaseous phase using the reflected wave from the inside of the water level measurement pipe | tube 4 is the same as that of Example 1. FIG. In the present embodiment, since the reflecting plate 24 is attached, a received signal having a high S / N ratio having a larger amplitude than the reflected wave from the inner wall 4b can be obtained. For this reason, specification of the reflected wave 31c in the water level calculation means 23 becomes easy. Further, the reliability of the determination of the gas phase and the liquid phase using the waveform amplitude of the reflected wave 31c and the amplitude ratio V is also increased.

  Moreover, the sound speed calculating means 27 calculates the sound speed v of the ultrasonic wave according to the above-described equation (2). Here, since the relationship between the sound velocity v of the ultrasonic pulse and the liquid phase temperature is known, the liquid phase temperature is known. Therefore, it is possible to confirm whether devices such as the ultrasonic transmission / reception means 11a, 11b, and 11c are used within the specified temperature range.

The reflected wave of the ultrasonic pulse transmitted by the ultrasonic transmission / reception means 13 is received by the ultrasonic transmission / reception means 13. The reflected wave at the liquid level is detected by the second control means 25 and transmitted to the second water level calculation means 26 together with the value of the sound velocity v of the ultrasonic pulse. From the time difference to the ultrasonic transmitting and receiving means 13 receives the reflected wave at the liquid surface from the transmission of the ultrasonic pulse, the propagation time t _l in an ultrasonic liquid phase is obtained. The second water level calculation means 26 calculates the water level l using the following equation (3).

  In this way, the sound speed is obtained when the water level is measured from the lateral direction of the water level measuring tube 4, and the water level is continuously measured by using the received signal and the sound speed v of the ultrasonic wave receiving means 13 provided at the lower end of the water level measuring tube 4. Can be measured.

  As described above, according to the liquid level measuring device of the present embodiment, since the reflection plate 24 having a high reflectance is attached to the inner wall 4b, a reflected wave with a high S / N having a large waveform amplitude can be obtained. The determination of the liquid phase / gas phase using waves becomes easy, and the reliability of measurement can be improved.

  Further, it is possible to obtain the liquidus temperature using the reflected wave from the inner wall 4a and the reflected wave from the reflecting plate 24. By obtaining the liquid phase temperature, it can be confirmed that the ultrasonic transmission / reception means 11a, 11b, 11c are used within the specified temperature range, and the water level can be measured with high reliability.

  Moreover, continuous water level measurement can be performed using the reflected wave of the ultrasonic pulse that propagates through the liquid phase from the lower end of the liquid phase and reflects off the liquid surface. In addition, the water level can be measured with high reliability without being affected by the change in the surface state of the liquid tank wall.

  A third embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as Example 1, and the overlapping description is abbreviate | omitted. FIG. 9 shows an enlarged view of the water level measuring tube to which the liquid level measuring device according to this embodiment is attached. In this embodiment, a delay means 28 is provided instead of the modulation means 22. The delay means 18 is installed outside the reactor containment vessel, such as outside the central control room or the management area, like the control means 21 and the like.

  The delay means 28 is connected to the high voltage generation circuit of the control means 21 and is a delay circuit that delays the electrical signal output from the control means 21 by a set time and inputs it to each ultrasonic transmission / reception means.

  The delay means 28 transmits an ultrasonic pulse at intervals with respect to the instruction signal transmitted from the control means 21 to each ultrasonic transmission / reception means with a pair of opposed ultrasonic transmission / reception means as a unit. An instruction signal is transmitted by setting a delay time. For example, in the example shown in FIG. 9, first, ultrasonic pulses are transmitted from the ultrasonic transmission / reception means 11a, 12a, then ultrasonic pulses are transmitted from the ultrasonic transmission / reception means 11b, 12b with a time interval, and then The delay time is set so that ultrasonic pulses are transmitted from the ultrasonic transmission / reception means 11c, 12c with a time interval.

  By controlling the timing of transmitting ultrasonic pulses in this way, for example, when using the ultrasonic transmission / reception means 11a, 12a, ultrasonic pulses are not transmitted from other ultrasonic transmission / reception means. Even if the sound wave pulse is not modulated, it is possible to determine the water level with high reliability without erroneously determining from which ultrasonic wave transmitting / receiving means each ultrasonic pulse is transmitted. In this case, since the ultrasonic wave transmission / reception means other than the ultrasonic transmission / reception means 11a and 12a receive the transmitted wave and the oblique transmission wave of the ultrasonic pulse, the reflected wave and the transmission wave are transmitted as in the case of using the modulation means 22. It is possible to make a determination using a wave and an oblique transmission wave.

  As described above, a plurality of determination results can be obtained for each water level as to whether it is a liquid phase or a gas phase. These determination results are determined by selecting the highest priority determination, determining each weighted determination, adopting a large number of determination results, determining classification using a neural network such as a support vector machine, etc. By determining whether the phase is the gas phase or not, the water level can be determined with high reliability.

  As described above, according to the liquid level measurement device of the present embodiment, the delay time is set so that the ultrasonic pulses are transmitted with a time interval as a unit of the pair of ultrasonic transmission / reception means installed opposite to each other. Thus, it is possible to perform highly reliable water level determination without individually modulating ultrasonic pulses without erroneously determining the ultrasonic pulses transmitted by other ultrasonic transmission / reception means.

  In addition, it is possible to use judgment by reflected wave, transmitted wave, and oblique angle transmitted wave in combination, and it is possible to measure the water level with high reliability.

  In addition, it is highly reliable in high temperature and high radiation environments by installing transmission / reception means, delay means, and water level calculation means outside the reactor containment vessel outside the central control room and control area, etc. Water level measurement is possible.

  A fourth embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as Example 1, and the overlapping description is abbreviate | omitted. FIG. 10 is a partial enlarged cross-sectional view showing the water level measuring tube 4 to which the liquid level measuring device according to the present embodiment is attached in an enlarged cross section perpendicular to the axial direction. In the present embodiment, ultrasonic transmission / reception means 11 a, 12 a, 14 a, 15 a are attached to the water level measurement tube 4 and are electrically connected to the control means 21, respectively. Other configurations are not shown.

  In this embodiment, a plurality of ultrasonic transmission / reception means are attached in the circumferential direction of the water level measuring tube 4. The determination of the gas phase and the liquid phase using the reflected wave or the transmitted wave is the same as the method described in the first embodiment.

  According to the liquid level measurement device of the present embodiment, by installing a plurality of ultrasonic transmission / reception means in the circumferential direction of the water level measurement tube, for the same water level, a plurality of determination results as to whether the liquid phase or the gas phase is obtained, The water level can be measured with high reliability without being affected by changes in the surface state of the liquid tank wall.

  In the present embodiment, four ultrasonic transmission / reception means 11a, 12a, 14a, 15a are attached. For example, in the second embodiment, the inner wall of the water level measurement tube 4 on the side where the ultrasonic transmission / reception means 14a is attached is used. It is also possible to provide the reflection means 24 described above and attach only the ultrasonic transmission / reception means 11a, 12a, 14a. Of course, there is no limit on the number of ultrasonic transmission / reception means attached in the circumferential direction.

  The embodiments of the present invention have been described above with reference to the drawings. However, a configuration in which the features described in the plurality of embodiments are arbitrarily combined may be used. For example, in the third embodiment, the delay unit 28 is used in place of the modulation unit 22, but may be used in combination. Moreover, since the measurement by the reflected wave is possible even if the ultrasonic transmission / reception means is not a pair, some or all of the ultrasonic transmission / reception means may not be a pair. Moreover, in each Example, although the water level measurement of the reactor pressure vessel was demonstrated to the example, the application object of the liquid level measuring device by this invention is not limited to a reactor pressure vessel.

DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 2 Upper pipe 3 Lower pipe 4 Water level measuring pipe 4a, 4b Inner wall 5 Liquid surface 11, 11a, 11b, 11c, 12, 12a, 12b, 12c, 13, 14a, 15a Ultrasonic transmission / reception means 21 Control means 22 Modulating means 23 Water level calculating means 24 Reflector 24a Recess 25 Second control means 26 Second water level calculating means 27 Sonic speed calculating means 28 Delay means 31a Ultrasound 31b, 31c Reflected wave 31d Transmitted wave 31e Obliquely transmitted wave

Claims (15)

An ultrasonic transmission / reception means attached to the outer wall of the pipe for transmitting / receiving ultrasonic waves;
Control means for transmitting an instruction signal for transmitting ultrasonic waves into the pipe to the ultrasonic transmission / reception means;
Receiving means for receiving an ultrasonic reception signal of the ultrasonic transmitting / receiving means;
Based on the ultrasonic reception signal received by the reception means, it is determined whether the ultrasonic wave received by the ultrasonic transmission / reception means includes a reflected wave reflected by the pipe inner wall on the side facing the ultrasonic transmission / reception means. And a liquid level measuring device.   The liquid level measuring device according to claim 1, further comprising a scanning unit that scans the ultrasonic transmission / reception unit in an axial direction of the pipe.   2. The liquid level measuring device according to claim 1, further comprising reflecting means attached to the inner wall of the pipe on the side facing the ultrasonic transmitting / receiving means. An ultrasonic transmission / reception means attached to the outer wall of the pipe for transmitting / receiving ultrasonic waves;
Second ultrasonic transmission / reception means attached to the pipe outer wall on the side facing the ultrasonic transmission / reception means;
Control means for transmitting an instruction signal for transmitting ultrasonic waves into the pipe to the ultrasonic transmission / reception means;
Receiving means for receiving an ultrasonic reception signal of the second ultrasonic transmitting / receiving means;
An operation for determining whether the ultrasonic wave received by the second ultrasonic transmission / reception unit includes a transmitted wave transmitted from the ultrasonic transmission unit and transmitted through the pipe based on the ultrasonic transmission / reception signal received by the reception unit. And a liquid level measuring device.   The ultrasonic transmission / reception means and the second ultrasonic transmission / reception means are arranged at different heights in the axial direction of the pipe, and the transmitted wave is obliquely transmitted obliquely incident on the axial direction of the pipe. The liquid level measuring device according to claim 4, wherein   6. The liquid level measuring device according to claim 1, wherein a plurality of the ultrasonic wave receiving means are provided in the axial direction of the pipe.   The liquid level measuring device according to any one of claims 4 to 6, wherein a plurality of the second ultrasonic wave receiving means are provided in the axial direction of the pipe.   The liquid level measuring device according to claim 1, further comprising a modulating unit that modulates the instruction signal.   9. The liquid level measuring device according to claim 1, further comprising delay means for setting a delay time for transmission of the instruction signal.   10. The liquid level measuring device according to claim 1, wherein a plurality of the ultrasonic receiving means or the second ultrasonic receiving means are attached in a circumferential direction of the pipe. Based on the received signal received by the received signal, a sound speed calculating means for obtaining a sound speed in the pipe,
A third ultrasonic transmitting / receiving means attached to the lower end of the pipe;
Second control means for transmitting an instruction signal for causing the third ultrasonic means to transmit ultrasonic waves into the pipe;
Second receiving means for receiving an ultrasonic reception signal of the third ultrasonic transmitting / receiving means;
A liquid level calculation means for calculating a liquid level using a time difference from when the third ultrasonic transmission / reception means transmits an ultrasonic wave until receiving the ultrasonic wave and a sound speed obtained by the sound speed calculation means; The liquid level measuring device according to claim 1, wherein the liquid level measuring device is a liquid level measuring device. A first ultrasonic transmission / reception means attached to the outer wall of the pipe for transmitting / receiving ultrasonic waves;
A second ultrasonic transmission / reception means attached at a position facing the first ultrasonic transmission / reception means across the pipe;
Third ultrasonic transmission / reception means attached to the first ultrasonic transmission / reception means and different positions in the pipe axis direction;
A fourth ultrasonic transmission / reception means attached to a position facing the third ultrasonic transmission / reception means across the pipe;
Control means for transmitting an instruction signal that causes each of the first ultrasonic transmission / reception means, the second ultrasonic transmission / reception means, the third ultrasonic transmission / reception means, and the fourth ultrasonic transmission / reception means to transmit ultrasonic waves into the pipe. When,
Receiving means for receiving ultrasonic reception signals of each of the first ultrasonic transmission / reception means, the second ultrasonic transmission / reception means, the third ultrasonic transmission / reception means, and the fourth ultrasonic transmission / reception means;
Based on the ultrasonic reception signal, each of the first ultrasonic transmission / reception means, the second ultrasonic transmission / reception means, the third ultrasonic transmission / reception means, and the fourth ultrasonic transmission / reception means is arranged on the opposite side of the pipe. Presence / absence of reflected wave from inner wall, presence / absence of transmitted wave from ultrasonic transmitting / receiving means at opposite position, transmitted wave from ultrasonic receiving means attached to outer wall on opposite side of pipe at different positions in pipe axis direction A liquid level measuring device comprising: an arithmetic means for determining the presence or absence of the liquid level.   The number of installed ultrasonic receiving means and the second ultrasonic receiving means is determined based on at least one of a measurement range or measurement accuracy of a water level in the pipe. The liquid level measuring device according to any one of the preceding claims.   The liquid according to any one of claims 6 to 7, wherein the number of the ultrasonic receiving means and the second ultrasonic receiving means is determined from a water level line set in the pipe. Position measuring device.   The liquid level measuring device according to any one of claims 6 to 7, wherein two each of the ultrasonic wave receiving means and the second ultrasonic wave receiving means are installed from the water level in the pipe.

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