JP6149587B2 - Ultrasonic flow meter - Google Patents

Description

  The present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid flowing in a pipe using an ultrasonic signal, and in particular, it is possible to measure the flow rate with high accuracy even when the fluid to be measured is not full in the pipe. Relates to an ultrasonic flowmeter.

  Various types of ultrasonic flowmeters have been proposed, and a propagation time difference method is known as a typical method. In the flow rate measurement using the propagation time difference method, as shown in FIG. 14A, ultrasonic sensors 510a and 510b capable of transmitting and receiving ultrasonic signals are installed upstream and downstream of the pipe 500 through which the fluid F to be measured flows. Ultrasonic signals are transmitted and received to measure their propagation times.

  When there is no flow of the fluid F to be measured, the ultrasonic signal propagates from the upstream ultrasonic sensor 510a to the downstream ultrasonic sensor 510b and the ultrasonic signal from the downstream ultrasonic sensor 510b to the upstream ultrasonic sensor 510a. However, when there is a flow, the upstream ultrasonic sensor 510a propagates faster from the upstream ultrasonic sensor 510a than the upstream ultrasonic sensor 510a. To do. Since the difference in propagation time is proportional to the flow speed, the flow velocity of the fluid F to be measured can be measured based on this difference. The obtained flow velocity is an average value of the flow velocity in the path of the ultrasonic signal. The flow rate is calculated by multiplying the flow velocity by the cross-sectional area of the pipe 500 and the correction coefficient.

  Further, as a method other than the propagation time difference method, it is assumed that bubbles and particles contained in the fluid F to be measured in the pipe 500 move at the same speed as the fluid F to be measured, and the moving speed is measured with an ultrasonic signal. There are also known a pulse Doppler method and a reflection correlation method for creating a flow velocity distribution (flow velocity profile) along the diameter of the pipe 500 and calculating the flow rate of the fluid F to be measured.

  In the pulse Doppler method, as shown in FIG. 14B, an ultrasonic pulse signal having a specific frequency is incident obliquely into the pipe 500 from the ultrasonic sensor 510c, and bubbles, particles, etc. contained in the fluid F to be measured. The echo wave reflected by the ultrasonic reflector is received by the ultrasonic sensor 510c.

  The frequency of the echo wave reflected by the ultrasonic reflector changes according to the moving speed of the ultrasonic reflector due to the Doppler effect. Therefore, by detecting the amount of change, the echo wave of the fluid F to be measured flowing in the pipe 500 is detected. The speed can be determined.

  Since reflection by the ultrasonic reflector occurs in various places in the pipe 500, the flow velocity profile of the fluid F to be measured in the radial direction is obtained based on the time from when the ultrasonic signal is emitted until the echo wave is detected. be able to. FIG. 15 shows an example of the flow velocity profile. By integrating this flow velocity profile along the cross section of the pipe 500, the flow rate of the fluid F to be measured can be calculated.

  Similarly to the pulse Doppler method, the reflection correlation method is also configured as shown in FIG. 14B, and outputs an ultrasonic pulse signal twice from the ultrasonic sensor 510c into the pipe 500, and moves in the fluid together with the fluid. An echo wave from the ultrasonic reflector is received.

  Then, the correlation calculation is performed on the two received echo waves, with one being a reference wave and the other being a search wave. As a result, the waveform with a high correlation coefficient is regarded as an echo wave from the same ultrasonic reflector, and by calculating the position and moving speed of the ultrasonic reflector based on the propagation time and the time difference, The flow rate profile is obtained and the flow rate of the fluid is calculated.

  For example, as shown in FIG. 16, there is a time difference between an echo wave T1 for the first ultrasonic pulse signal regarded as an echo wave from the same ultrasonic reflector and an echo wave T2 for the second ultrasonic pulse signal. ΔT corresponds to the distance of the ultrasonic reflector that has traveled between the first ultrasonic pulse signal and the second ultrasonic pulse signal, that is, the velocity of the fluid F to be measured, and the propagation time Td is the ultrasonic wave This corresponds to the distance of the reflector from the ultrasonic sensor 510c, that is, the radial position in the pipe 500 of the ultrasonic reflector. Since reflection by the ultrasonic reflector occurs in various places in the pipe 500, a flow velocity profile can be obtained in the radial direction in the pipe. The flow rate of the fluid is calculated by integrating the flow velocity profile along the cross section of the pipe 500.

  Generally, in an ultrasonic flowmeter, the flow rate of the fluid to be measured F is measured, and the flow rate is calculated by multiplying the cross-sectional area of the piping 500, so that the piping 500 is filled with the fluid F to be measured. This is the measurement condition.

  On the other hand, Patent Documents 1 and 2 propose ultrasonic flowmeters that can measure the flow rate even in a non-full state. As shown in FIG. 17A, the ultrasonic flow meter described in Patent Document 1 includes an ultrasonic sensor 510 d above the pipe 500 with respect to the fluid F to be measured that flows in the pipe 500 and is not full. The ultrasonic sensor 510e is installed at an interval in the axial direction, and the ultrasonic signal emitted from the ultrasonic sensor 510d is reflected at the interface and is incident on the ultrasonic sensor 510e.

  Then, the flow velocity of the fluid F to be measured is calculated from the frequency change due to the Doppler effect of the ultrasonic signal detected by the ultrasonic sensor 510e. Further, the height of the interface is calculated from the propagation time of the ultrasonic signal from the ultrasonic sensor 510d to the ultrasonic sensor 510e, and the cross-sectional area of the fluid F to be measured is obtained. It is described that the flow rate of the fluid F to be measured in a non-full state can be obtained by multiplying the calculated flow velocity and the cross-sectional area.

  As shown in FIG. 17 (b), the ultrasonic flowmeter described in Patent Document 2 is connected to an ultrasonic sensor 510 f below the pipe 500 with respect to the fluid F to be measured flowing through the pipe 500. The ultrasonic sensor 510g is installed at an interval in the axial direction, the time T1 from when the ultrasonic sensor 510f is emitted from the ultrasonic sensor 510f until it is reflected at the interface and incident on the ultrasonic sensor 510g, and the ultrasonic sensor 510g is emitted. Then, a time T2 from when the light is reflected at the interface until it enters the ultrasonic sensor 510f is measured.

  Then, based on the obtained times T1 and T2, the flow velocity and the interface height are calculated, and by multiplying the calculated flow velocity and the fluid cross-sectional area based on the interface height, the measurement fluid F in a non-full state is measured. It is described that a flow rate can be obtained.

JP 2000-266578 A JP 2005-49249 A

  In general, the flow rate calculation using the flow velocity profile can calculate the flow rate by evaluating the ratio of the area area of the pipe area to the pipe cross-sectional area, from the flow rate of the outer circumference side area of the pipe 500 to the flow speed of the inner circumference side area. The flow rate can be measured with higher accuracy than when the flow rate is calculated simply by multiplying the average flow velocity by the cross-sectional area.

  In the invention described in Patent Document 1, the flow velocity of the fluid F to be measured is calculated from the frequency change due to the Doppler effect of the ultrasonic signal reflected at the interface. The flow velocity obtained at this time is the flow velocity at the interface portion. Since the flow velocity distribution of the fluid F to be measured is not taken into account, the accuracy is not sufficient.

  The invention described in Patent Document 2 calculates the flow velocity of the fluid F to be measured using the propagation time difference method. The flow velocity obtained at this time is the average flow velocity of the path of the ultrasonic signal, Since the flow velocity distribution of the fluid F to be measured is not considered, the accuracy is not sufficient.

  Accordingly, an object of the present invention is to provide an ultrasonic flowmeter capable of measuring a flow rate with high accuracy even when a fluid to be measured is in a non-full state in a pipe.

In order to solve the above problems, an ultrasonic flowmeter of the present invention emits an ultrasonic pulse into a pipe through which a fluid to be measured flows, and a flow velocity based on a reflected signal from an ultrasonic reflector included in the fluid to be measured. An ultrasonic flowmeter for creating a profile, a reflected signal intensity profile creating unit for creating a reflected signal intensity profile based on the received intensity of the reflected signal, and an interface for specifying an interface position based on the reflected signal intensity profile And a flow rate calculation unit configured to calculate a flow rate of the fluid to be measured based on the determination unit, the flow velocity profile, and the interface position.
Here, the interface determination unit can specify a maximum position that is equal to or greater than a predetermined reference of the reflected signal intensity in the reflected signal intensity profile as the interface position.
Further, the flow rate calculation unit divides the inside of the pipe into upper and lower parts, and further divides it into a plurality of semicircular arc shaped areas, and multiplies the area below the interface position of each area by the flow velocity obtained from the flow velocity profile. The flow rate of the fluid to be measured can be calculated by summing the flow rates of the obtained regions.
In addition, a flow time difference measurement unit that performs flow rate measurement by the propagation time difference method is further provided, and the flow rate calculation unit, when the measurement result by the propagation time difference method does not satisfy a predetermined reference, the flow velocity profile and the interface position The flow rate may be calculated based on the above.

  ADVANTAGE OF THE INVENTION According to this invention, even if the to-be-measured fluid is a non-full state in piping, the ultrasonic flowmeter which can measure a flow volume with high precision is provided.

It is a block diagram which shows the structure of the ultrasonic flowmeter which concerns on 1st Example of this invention. It is a flowchart explaining the procedure of the flow measurement in the ultrasonic flowmeter of 1st Example. It is a figure which shows the flow velocity profile and reflective signal strength profile when the fluid to be measured is full in the piping. It is a figure which shows the flow-velocity profile and reflected signal strength profile when the fluid to be measured is a non-full state in the pipe. It is a flowchart explaining in detail the flow volume calculation which a flow volume calculation part performs. It is a flowchart explaining in detail the flow volume calculation which a flow volume calculation part performs. It is a figure explaining the integration in the case of a full condition. It is a figure explaining the integration when an interface is below a center in a non-full state. It is a figure explaining the example of integration when an interface is below a center in a non-full state. It is a figure explaining the integration when an interface is higher than a center in a non-full state. It is a figure explaining the example of integration when an interface is higher than the center in a non-full state. It is a block diagram which shows the structure of the ultrasonic flowmeter which concerns on 2nd Example of this invention. It is a flowchart explaining the procedure of the flow measurement in the ultrasonic flowmeter of 2nd Example. It is a figure which shows the structure of the conventional ultrasonic flowmeter. It is a figure which shows the example of a flow velocity profile. It is a figure explaining the echo wave in a reflection correlation method. It is a figure which shows the structure of the conventional ultrasonic flowmeter which can be measured in a non-full state.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ultrasonic flowmeter according to a first example of an embodiment of the present invention. In this example, the ultrasonic flowmeter measures the flow rate of the fluid F to be measured flowing through the pipe 500. The fluid F to be measured may be in a full water state that fills the entire pipe 500 or may be in a non-full state having a space in the upper part.

  As shown in the figure, the ultrasonic flowmeter includes an ultrasonic sensor 210 and a measurement control unit 100. The ultrasonic flowmeter according to the first embodiment of the present invention uses either the pulse Doppler method or the reflection correlation method.

  The ultrasonic sensor 210 is a device that transmits and receives an ultrasonic signal, and is attached to the lower portion outside the pipe 500 so that the ultrasonic signal is emitted obliquely in the pipe axis direction. That is, the ultrasonic flowmeter of the present embodiment can measure the flow rate without contacting the fluid F to be measured.

  The measurement control unit 100 includes an output control unit 110, a reception control unit 120, a flow velocity profile creation unit 130, a reflected signal intensity profile creation unit 140, an interface determination unit 150, a flow rate calculation unit 160, and a measurement result output unit 170.

  The output control unit 110 performs output control of the ultrasonic signal, and the reception control unit 120 performs reception control of the ultrasonic signal. The ultrasonic signal to be received by the reception control unit 120 is an echo wave from the ultrasonic reflector included in the fluid F to be measured with respect to the ultrasonic signal output by the output control unit 110.

  The flow velocity profile creation unit 130 creates a flow velocity profile in the diameter (up and down) direction of the pipe 500 based on the ultrasonic signal received by the reception control unit 120. The reflected signal intensity profile creation unit 140 creates a reflected signal intensity profile for the diameter (up and down) direction of the pipe 500 based on the ultrasonic signal received by the reception control unit 120.

  Here, the reflected signal intensity profile represents the reflected signal intensity distribution in the diameter (up and down) direction of the pipe 500 based on the echo wave detection time after measuring the intensity of the echo wave from the ultrasonic reflector. is there. Although the ultrasonic flowmeter according to the first embodiment uses either the pulse Doppler method or the reflection correlation method, other methods can be used as long as the flow velocity profile and the reflected signal intensity profile can be created. Good.

  The interface determination unit 150 determines the presence or absence of an interface based on the reflected signal intensity profile, and further specifies the height S of the interface when there is an interface. This utilizes the fact that the reflected signal intensity becomes strong at the interface in contact with the gas. The flow rate calculation unit 160 calculates the flow rate of the fluid F to be measured based on the flow velocity profile, the presence or absence of an interface, and the height S of the interface when there is an interface. The measurement result output unit 170 outputs the calculated flow rate of the fluid F to be measured as a measurement result.

  Next, the flow rate measurement procedure in the ultrasonic flowmeter of the first embodiment will be described with reference to the flowchart of FIG. First, various settings for measurement are performed (S101). In various settings, the inner diameter of the pipe 500, the mounting angle of the ultrasonic sensor 210, the density / viscosity of the fluid F to be measured, the speed of sound, and other parameters are set.

  When various settings are made, measurement is performed by either the pulse Doppler method or the reflection correlation method (S102). In either method, measurement is performed by repeatedly outputting ultrasonic signals so that a profile can be created.

  In the case of the pulse Doppler method, an ultrasonic pulse signal having a specific frequency is output into the pipe 500, and an echo wave reflected by the ultrasonic reflector is received by the ultrasonic sensor 210. The change in frequency and the received intensity at this time are measured for each detection time. In the case of the reflection correlation method, an ultrasonic pulse signal is output twice and an echo wave from the ultrasonic reflector is received. The waveform having a high correlation coefficient is regarded as an echo wave from the same ultrasonic reflector, and the position and moving speed of the ultrasonic reflector are calculated based on the propagation time and the time difference, and the received intensity Measure.

  Based on the result obtained by repeating the measurement, the flow velocity profile creating unit 130 creates a flow velocity profile (S103), and the reflected signal intensity profile creating unit 140 creates a reflected signal intensity profile (S104).

  Next, the interface determination unit 150 determines the presence or absence of an interface based on the reflected signal intensity profile, and if there is an interface, specifies the height S of the interface (S105). Here, if the fluid F to be measured is full in the pipe 500, generally, a flow velocity profile and a reflected signal intensity profile as shown in FIG. 3 are obtained.

  On the other hand, as shown in FIG. 4A, when the fluid F to be measured is in a non-full state and an interface exists, as shown in FIG. It becomes extremely large several times at the corresponding position. This is because many reflected signals are obtained from the gas filling the upper part at the interface.

  For this reason, the interface determination unit 150 can determine the presence or absence of an interface based on whether or not the reflected signal intensity profile has a maximum portion that exceeds a predetermined reference, and can specify the height S of the interface at the position of the maximum portion.

  When the interface is determined, the flow rate calculation unit 160 integrates the flow velocity profile in the cross-sectional range of the fluid F to be measured to calculate the flow rate (S106), and the measurement result output unit 170 outputs the calculated flow rate as the measurement result. (S107).

  Here, the flow rate calculation performed by the flow rate calculation unit 160 will be described in detail with reference to the flowcharts of FIGS. 5 and 6. However, the flow rate calculation method described below is an example, and other methods may be used as long as the flow rate is calculated using the interface height and the flow velocity profile obtained from the reflected signal intensity profile.

  First, based on the determination result of the interface determination unit 150, it is determined whether or not the fluid F to be measured is full (S201).

  Here, the integration in the case of the full water state will be described with reference to FIG. In this figure, the flow velocity profile is displayed such that the lower part of the pipe is located below and the upper part of the pipe is located above, and is divided into a plurality of sections in the height direction. This division width is defined as an integration width. Each section can be associated with the flow velocity by calculating the average flow velocity of the section. The finer the integral width, the more accurate the flow rate calculation.

  For example, when attention is paid to the lowermost section as shown in FIG. 7A, the flow velocity of this section can be applied to the outermost peripheral area of the lower half. For this reason, if the area of the outermost peripheral region of the lower half is obtained and multiplied by the flow velocity of the corresponding section, the flow rate of the outermost peripheral region of the lower half is calculated. Since the radius of the pipe 500 is known, the area of the outermost peripheral region can be easily obtained using the set integral width. This calculation is performed for each of the lower half and the upper half as shown in FIG. 7B, and the flow rate of the fluid F to be measured is calculated by summing the flow rates in the areas corresponding to the respective divisions. .

  Therefore, when the water is full (S201: Yes), an integration width is set (S202), and the area of each region is calculated for the lower half and integration is performed by multiplying the corresponding flow rate (S203). Similarly, for the upper half, the area of each region is calculated and integration is performed by multiplying the flow rate of the corresponding section (S204). And the flow volume of each area | region is totaled (S205).

  Returning to the description of the flowchart of FIG. 5, when the state is not full (S201: No), the case is divided depending on whether the interface is below the center (S206). Here, the integration when the interface is below the center will be described with reference to FIG. For example, when the interface height S is specified as shown in FIG. 8A, as shown in FIG. 8B, the area up to the interface for each semicircular arc-shaped region having an integral width thickness. Can be calculated and multiplied by the flow rates of the corresponding sections.

  Therefore, when the interface is below the center (S206: Yes), the integration width is set (S207), and the target region is set in the lower half (S208). FIG. 9A shows an example in which the outermost peripheral portion is the target region.

  Then, from the radius R and height H of the target area, an angle θ that is half the center angle of the target area is calculated (S209). Here, the radius R is a fan-shaped radius with the outer periphery of the target region as an arc, and the height H is the height from the lowermost part of the outer periphery of the target region to the interface. At this time, since cos θ = (R−H) / R holds, the angle θ can be calculated. When the outermost peripheral portion is the target region, the radius R is equal to the radius of the pipe 500, and the height H is equal to the interface height S.

  If the angle θ is obtained, the radius R with the outer periphery of the region as an arc and the fan-shaped area with the central angle 2θ, the radius with the inner periphery of the region as an arc (R−integral width d), and the sector-shaped area with the central angle 2θ. The area of the target region can be calculated by subtracting (S210). The flow rate of the target region is calculated by multiplying the flow velocity of the section corresponding to this area (S211).

  The above-described process for calculating the flow rate of the target area is repeated for the entire lower half area (S212). FIG. 9B and FIG. 9C show the radius R, height H, and center angle θ when the target region is changed.

  When the process of calculating the flow rate is performed for the entire lower half region (S212: Yes), the flow rates of the respective regions are summed (S213).

  Next, integration when the interface is greater than or equal to the center will be described with reference to FIG. For example, when the interface height S is specified as shown in FIG. 10 (a), as shown in FIG. 10 (b), the lower half of each semicircular arc-shaped region having an integral width thickness is used. What is necessary is just to calculate an area and multiply by the flow velocity of a corresponding division. On the other hand, for the upper half, the area up to the interface is calculated for each semicircular arc-shaped region having the thickness of the integral width, and multiplied by the flow rate of the corresponding section.

  Therefore, when the interface is higher than the center (S206: No), the integration width is set (FIG. 6: S207), and the lower half integration is executed (S215). The upper half of the integration is performed as follows.

  First, the target area is set in the upper half (S216). FIG. 11A shows an example in which the outermost peripheral portion is the target region. Then, it is determined whether or not the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface (S217). Here, when the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface, the upper part of the target area is cut off by the interface and divided into two left and right parts. On the other hand, when the radius R of the target area is smaller than the height K from the center of the pipe 500 to the interface, the target area does not cross the interface and remains in a semicircular arc shape.

  11A and 11B show a case where the radius R of the target region is larger than the height K from the center of the pipe 500 to the interface, and FIG. 11C shows that the radius R of the target region is the pipe. This is a case where the height from the 500 center to the interface is smaller than K.

  When the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface (S217: Yes), one area of the target area is calculated from the radius R and the height K from the center of the pipe 500 to the interface. Is calculated (S218). Here, as shown in FIGS. 11A and 11B, since sin θ = K / R holds, the angle θ can be calculated. When the outermost peripheral portion is the target region, the radius R is equal to the radius of the pipe 500, and the height K is equal to the value obtained by subtracting the radius of the pipe 500 from the interface height S.

  On the other hand, when the radius R of the target region is smaller than the height K from the center of the pipe 500 to the interface (S217: No), θ may be uniformly set to 90 ° (S219).

  If the angle θ is obtained, the radius R with the outer periphery of the region as an arc, the radius of the sector angle of the central angle θ from twice the sector area, the radius with the inner periphery of the region as an arc (R−integral width d), and the central angle θ The area of the target region can be calculated by subtracting twice the fan-shaped area (S220). The flow rate of the target region is calculated by multiplying the flow velocity of the section corresponding to this area (S221).

  The above process for calculating the flow rate of the target area is repeated for the entire upper half area (S222). When the flow rate is calculated for the entire upper half region (S222: Yes), the flow rates of the lower and upper half regions are summed (S223).

  The first example of the present embodiment has been described above. Next, a second example of the present embodiment will be described. The ultrasonic flow meter in the second embodiment is obtained by adding a measurement function by the propagation time difference method to the ultrasonic flow meter of the first embodiment.

  FIG. 12 is a block diagram showing a configuration of an ultrasonic flowmeter according to the second embodiment of the present invention. The same reference numerals are assigned to the same blocks as in the first embodiment. In this example, the ultrasonic flowmeter measures the flow rate of the fluid F to be measured flowing through the pipe 500. The fluid F to be measured may be in a full water state that fills the entire pipe 500 or may be in a non-full state having a space in the upper part.

  As shown in the figure, the ultrasonic flowmeter of the second embodiment includes an ultrasonic sensor 210 a in addition to the ultrasonic sensor 210, and includes a measurement control unit 101 instead of the measurement control unit 100. The ultrasonic sensor 210a is installed in a position above the pipe 500 at a position where the ultrasonic sensor 210 can receive an ultrasonic signal obliquely emitted from the ultrasonic sensor 210 and the ultrasonic sensor 210 can receive an ultrasonic signal emitted from the ultrasonic sensor 210a. Is done.

  The measurement control unit 101 includes an output control unit 110, a reception control unit 120, a flow velocity profile creation unit 130, a reflected signal intensity profile creation unit 140, an interface determination unit 150, a flow rate calculation unit 160, a measurement result output unit 170, and a measurement method control unit. 180, a propagation time difference measurement unit 190 is provided.

  The measurement method control unit 180 controls the flow rate measurement using the propagation time difference method and the flow rate measurement using the pulse Doppler method or the reflection correlation method shown in the first embodiment. The propagation time difference method measurement unit 190 performs flow rate measurement using the propagation time difference method.

  A flow measurement procedure in the ultrasonic flowmeter of the second embodiment will be described with reference to the flowchart of FIG. First, various settings for measurement are performed (S301). In various settings, the inner diameter of the pipe 500, the mounting angle of the ultrasonic sensors 210 and 210a, the density / viscosity of the fluid F to be measured, the speed of sound, and other parameters are set.

  In the second embodiment, first, measurement using the propagation time difference method is executed (S302). This is because if the fluid F to be measured is full and there are few bubbles or the like, high accuracy can be obtained by measurement using the propagation time difference method. In the measurement using the propagation time difference method, ultrasonic signals are alternately transmitted and received between the ultrasonic sensors 210 and 210a, and the respective propagation times are measured.

  As a result, it is determined whether or not the ultrasonic signals emitted by the other ultrasonic sensors 210a and 210 can be received at a predetermined intensity by the respective ultrasonic sensors 210 and 210a (S303). Here, if the fluid F to be measured is in a non-full state, the ultrasonic signal from the other cannot be received. If the fluid F to be measured has many bubbles or the like, the reception intensity of the ultrasonic signal from the other is weak. In either case, flow rate measurement by the propagation time difference method is not suitable.

  When the ultrasonic signal emitted by the other side can be received at a predetermined intensity (S303: Yes), the flow rate is calculated by the propagation time difference method (S304), and the obtained flow rate is output as a measurement result (S307).

  On the other hand, when the ultrasonic signal emitted by the other cannot be received with a predetermined intensity (S303: No), the flow rate measurement shown in the first embodiment is performed. That is, the measurement using the pulse Doppler method or the reflection correlation method is executed (S305), and the flow rate calculation based on the interface height and the flow velocity profile obtained from the received signal intensity profile is executed (S306).

  If measurement is not possible even with the flow rate measurement shown in the first embodiment, for example, the processing after (S302) may be repeated again, and an alarm may be output if measurement is still not possible.

DESCRIPTION OF SYMBOLS 100 ... Measurement control part, 101 ... Measurement control part, 110 ... Output control part, 120 ... Reception control part, 130 ... Flow velocity profile creation part, 140 ... Reflection signal intensity profile creation part, 150 ... Interface determination part, 160 ... Flow rate calculation , 170 ... measurement result output unit, 180 ... measurement method control unit, 190 ... propagation time difference method measurement unit. 210 ... Ultrasonic sensor, 500 ... Piping, 510 ... Ultrasonic sensor

Claims (3)

An ultrasonic flowmeter that emits an ultrasonic pulse into a pipe through which a fluid to be measured flows, and creates a flow velocity profile based on a reflected signal from an ultrasonic reflector included in the fluid to be measured,
A reflected signal intensity profile creating unit that creates a reflected signal intensity profile based on the received intensity of the reflected signal;
An interface determination unit for specifying an interface position based on the reflected signal intensity profile;
Bei example and the flow velocity profile, and a flow rate calculation unit for calculating a flow rate of the fluid to be measured on the basis of said interface position,
The flow rate calculation unit is obtained by dividing the inside of the pipe into upper and lower parts, further dividing into a plurality of semicircular arc regions, and multiplying the area below the interface position of each region by the flow velocity obtained from the flow velocity profile. An ultrasonic flowmeter that calculates the flow rate of the fluid to be measured by summing the flow rates for each region .   2. The ultrasonic flowmeter according to claim 1, wherein the interface determination unit specifies a maximum position that is equal to or greater than a predetermined reference of the reflected signal intensity in the reflected signal intensity profile as an interface position.   It further includes a propagation time difference method measurement unit that performs flow rate measurement by the propagation time difference method,
  3. The flow rate calculation unit performs flow rate calculation based on the flow velocity profile and the interface position when a measurement result by a propagation time difference method does not satisfy a predetermined reference. Ultrasonic flow meter.