JP2016136103A - Ultrasonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter which can measure the flow rate of each layer of the multiphase flow in which plural kinds of fluids are separated in the layered state.SOLUTION: An ultrasonic flowmeter which emits an ultrasonic pulse into a pipe where a measurement object fluid flows, and generates a flow rate profile on the basis of a reflection signal from an ultrasonic reflection body included in the measurement object fluid comprises: a reflection signal intensity profile generation part which generates a reflection signal intensity profile on the basis of the reception intensity of the reflection signal; an interface determination part which specifies the number of interfaces and each interface position on the basis of the reflection signal intensity profile; and a flow rate calculation part which calculates the flow rate of the measurement object fluid for each layer divided by the interface on the basis of the flow rate profile and the interface position.SELECTED DRAWING: Figure 1

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, the flow rate of each layer even in a multiphase flow in which a plurality of types of fluids are separated into layers. The present invention relates to an ultrasonic flowmeter capable of measurement.

  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. 19A, 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 ultrasonic signal from the upstream ultrasonic sensor 510a to the downstream ultrasonic sensor is lower than the ultrasonic signal propagating from the downstream ultrasonic sensor 510b to the upstream ultrasonic sensor 510a. The ultrasonic signal propagating to 510b propagates faster, resulting in a difference in propagation time. 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 generating 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. 19B, an ultrasonic pulse signal having a specific frequency is incident obliquely into the pipe 500 from the ultrasonic sensor 510c, and bubbles or particles 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. 20 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. 19B, 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. 21, there is a time difference between the echo wave T1 for the first ultrasonic pulse signal regarded as an echo wave from the same ultrasonic reflector and the 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.

  Here, the integration performed when the flow rate is calculated will be described with reference to FIGS. FIG. 22 shows the flow velocity profile and the pipe cross section corresponding to each other, and FIG. 23 shows the integration procedure in a flowchart.

  In FIG. 22, 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. The inside of the pipe is divided into a plurality of regions on a concentric semicircle corresponding to the integral width.

  For example, when attention is paid to the lowermost section as shown in FIG. 22A, the flow velocity of this section can be applied to the outermost peripheral region of the lower half of the pipe. 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. 23 (b), and the flow rate of the fluid F to be measured can be calculated by summing the flow rates in the areas corresponding to the respective divisions.

  Therefore, when integrating, the integration width is set (FIG. 23: S801), and the area of each region is calculated for the lower half, and integration is performed by multiplying the corresponding flow rate (S802). 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 (S803). And the flow volume of each area | region is totaled (S804). Thereby, the flow rate of the fluid F to be measured is calculated.

JP 2000-266578 A JP 2005-49249 A

  Conventionally, measurement of flow rate with an ultrasonic flowmeter is intended for single-type fluids or mixed flows in which multiple types of fluids are completely mixed, and for multiphase flows in which multiple types of fluids are separated into layers, Although the overall average flow rate could be measured, the flow rate for each layer could not be measured.

  However, at the measurement site, multiphase flow may flow in the piping such as seawater and crude oil, heavy oil and light oil, and in this case, the flow rate varies depending on the layer. It is desired.

  Then, an object of this invention is to provide the ultrasonic flowmeter which can measure the flow volume of each layer about the multiphase flow from which the multiple types of fluid isolate | separated into the layer form.

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 flow meter for generating a profile, a reflected signal intensity profile generating unit for generating a reflected signal intensity profile based on the received intensity of the reflected signal, and the number of interfaces based on the reflected signal intensity profile and the respective An interface determination unit that identifies an interface position, and a flow rate calculation unit that calculates the flow rate of the fluid to be measured for each layer divided by the interface based on the flow velocity profile and the interface position. And
Here, the interface determination unit can determine that the maximum position of the reflected signal intensity in the reflected signal intensity profile is equal to or greater than a predetermined reference as an interface.
The flow rate calculation unit is a region obtained by dividing the inside of the pipe into concentric semicircular regions and multiplying the area of the region included in the flow rate calculation target layer by the flow velocity determined based on the flow velocity profile. By summing the flow rates for each layer, the flow rate for each layer of the fluid to be measured can be calculated.
At this time, the flow velocity determined based on the flow velocity profile applies the flow velocity profile when the flow velocity profile corresponding to the region exists, does not exist, and the same circle in the region does not exist. If there is a flow velocity profile corresponding to another area on the circumference, that flow velocity profile is applied, there is no flow velocity profile corresponding to that area, and there is also a flow velocity profile corresponding to another area on the same circumference of that area. If not present, a flow rate profile obtained by interpolating the flow rate profile of the layer can be applied.
Further, the full / non-full state of the pipe may be determined based on a reflection signal of an ultrasonic pulse emitted from a position facing the pipe.
At this time, the flow rate calculation unit can handle the interface between the gas layer and the fluid to be measured when the pipe is determined to be in a non-full state.
When the pipe is determined to be full and the number of interfaces is determined to be 0, the pipe may be switched to perform flow rate measurement by the propagation time difference method.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic flowmeter which can measure the flow volume of each layer is provided about the multiphase flow from which the multiple types of fluid isolate | separated into the layer form.

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 reflected signal intensity profile when a to-be-measured fluid is a single kind of single layer flow. It is a figure which shows the flow velocity profile and reflected signal intensity profile at the time of the multiphase laminar flow which a to-be-measured fluid consists of two types of fluids. It is a figure which shows the flow velocity profile and reflected signal strength profile at the time of the to-be-measured fluid which consists of three types of fluids in the multiphase laminar flow. It is a flowchart explaining in detail the flow volume calculation which a flow volume calculation part performs. It is a flowchart explaining the lowest layer flow calculation process. It is a figure explaining the lowest layer flow calculation process. It is a figure explaining the lowest layer flow calculation process. It is a figure explaining the lowest layer flow calculation process. It is a figure explaining the lowest layer flow calculation process. It is a flowchart explaining uppermost layer flow calculation processing. It is a flowchart explaining an intermediate | middle laminar flow calculation process. It is a flowchart explaining an intermediate | middle laminar flow calculation process. It is a figure explaining an intermediate laminar flow calculation process. It is a figure explaining an intermediate laminar flow calculation process. 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 flowchart explaining the procedure of the conventional flow volume calculation. It is a figure explaining the integration in the conventional flow volume calculation.

  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 to be measured F may be a single type of fluid or a mixed flow that is uniformly mixed, or may be a multi-layer flow in which a plurality of types of fluids are separated into layers.

  In the example of the figure, a two-layer flow in which the fluid F1 and the fluid F2 are layered is shown. In this case, the fluid F1 and the fluid F2 are collectively referred to as a fluid to be measured F. Note that the boundary between the fluid F1 and the fluid F2 is referred to as an interface. As shown in the figure, if there are two laminar flows, there is one interface, and if there are three laminar flows, there are two interfaces.

  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 outer lower portion of the pipe 500 so that the ultrasonic signal is emitted obliquely in the pipe axis direction (clamp-on method, semi-clamp-on method). That is, the ultrasonic flowmeter of the present embodiment can measure the flow rate without contacting the fluid F to be measured. However, an attachment method (spool piece method) in which the ultrasonic sensor 210 is inserted into the pipe 500 may be employed.

  The measurement control unit 100 includes an output control unit 110, a reception control unit 120, a flow velocity profile generation unit 130, a reflected signal intensity profile generation 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 generation unit 130 generates 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 generation unit 140 generates 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 generated. 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 intensity of the reflected signal is increased at the interface where the characteristics of the fluid change. 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. In the first embodiment, the number of layers of a multi-layer flow (including a single layer) flowing through the pipe 500 in a full state is determined, and the flow rate is measured for each layer.

  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, 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 generated.

  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 generator 130 generates a flow velocity profile (S103), and the reflected signal intensity profile generator 140 generates a reflected signal intensity profile (S104).

  Next, the interface determination unit 150 determines the presence / absence of an interface based on the reflected signal intensity profile, and if there is an interface, specifies the number of interfaces and their positions (S105). Here, if the fluid F to be measured is a single type of single-layer flow, generally, a flow velocity profile and a reflected signal intensity profile as shown in FIG. 3 are obtained. That is, the reflected signal intensity profile has a gentle shape without having an extremely changing portion except for the pipe wall surface on the side facing the mounting side of the ultrasonic sensor 210.

  On the other hand, when the fluid to be measured F is a multiphase flow composed of two kinds of fluids as shown in FIG. 4A and one interface exists, as shown in FIG. The reflected signal intensity profile becomes extremely large several times at the position corresponding to the interface.

  Similarly, when the fluid F to be measured is a multiphase flow composed of three kinds of fluids as shown in FIG. 5A and there are two interfaces, the reflected signal is shown in FIG. 5B. The intensity profile becomes very large at the two positions corresponding to the interface.

  For this reason, the interface determination unit 150 determines the presence or absence of an interface based on whether or not there is a local maximum portion that exceeds a predetermined reference in a location other than the pipe wall in the reflected signal intensity profile. Can be specified. Alternatively, the reflected signal intensity profile may be differentiated, and a portion where the reflected signal intensity profile is switched from positive to negative may be determined as the interface.

  After determining the number and height of the interfaces, the flow rate calculation unit 160 sets a calculation target layer (S106). For example, the calculation target layers can be set in order from the lowest layer.

  Then, the flow rate calculation is executed for the calculation target layer (S107), and the flow rate of the layer is calculated. The detailed procedure of the flow rate calculation process (S107) will be described later. When the flow rate calculation is performed on the calculation target layer and there is an unprocessed layer (S108: Yes), any unprocessed layer is set as the calculation target layer (S106), and the calculation target layer is set. The flow rate calculation is executed for (S107), and the flow rate of the calculation target layer is calculated. When there is no unprocessed layer (S108: No), that is, when the flow rate calculation is performed for all layers, the flow rate for each layer is output as a measurement result (S109).

  Next, a detailed procedure of the flow rate calculation process (S107) will be described with reference to the flowchart of FIG. When the integral width is set as in the conventional case (S201), if the layer to be calculated is the lowest layer (S202: Yes), the lowest layer flow rate calculation (S203) is performed, and the layer to be calculated is If it is the uppermost layer (S202: No, S204: Yes), the uppermost layer flow rate calculation (S205) is performed. If the calculation target layer is the intermediate layer (S202: No, S204: No), the intermediate layer A flow rate calculation (S205) is performed. When the fluid F to be measured is a single layer, the lowest layer flow rate calculation (203) is performed. The intermediate layer is a layer sandwiched between the lowermost layer and the uppermost layer when the fluid to be measured F has three or more layers.

<Lower layer flow rate calculation>
FIG. 7 is a flowchart showing the procedure of the lowest layer flow rate calculation (S203). In the lowest layer flow rate calculation, the case is divided depending on whether the upper interface position of the lowest layer is below the center of the pipe 500 (S301).

  As shown in FIG. 8A, if the interface position of the lowermost layer is below the center of the pipe 500 (S301: Yes), the upper part is shown for each integral width as shown in the hatched area of FIG. 8B. What is necessary is just to calculate the area of each semicircular area | region cut out, and to multiply by a corresponding flow velocity and to total.

  Therefore, a target area whose area is calculated in a predetermined order is set (S302). FIG. 9A shows a case where the outermost peripheral portion is the target region.

  Then, from the radius R and the height Hh of the target area, an angle θ that is half the central angle of the target area is calculated (S303). Here, the radius R is a fan-shaped radius with the outer periphery of the target region as an arc, and the height Hh 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−Hh) / 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.

  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 (S304). The flow rate of the target region is calculated by multiplying the flow velocity of the section corresponding to this area (S305).

  The above-described process for calculating the flow rate of the target area is repeated for the entire lower half area (S306). 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 on the entire lower half region (S306: Yes), the flow rates of the respective regions are summed (S307).

  As shown in FIG. 10 (a), if the upper interface position of the lowermost layer is equal to or higher than the center of the pipe 500 (S301: No), as shown in the hatched area of FIG. Similar integration processing is performed, and for the upper half, for each integration width, the area of each semicircular region or semicircular region with the upper part cut off may be calculated and multiplied by the corresponding flow velocity.

  However, there may be a region where the flow velocity profile of the calculation target layer does not exist, as in the thick line frame in FIG. In this case, the lower half flow velocity profile on the same circumference is used.

  Therefore, when the interface position of the lowermost layer is not less than the center of the pipe 500 (S301: Yes), the integration is executed in the same procedure as the conventional method for the lower half region (S308). The upper half of the integration is performed as follows.

  First, a target area is set in the upper half (S309). FIG. 11A shows an example in which the outermost peripheral portion is the target region. Then, it is determined whether the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface (S310). 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 (S310: 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 (S311). 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 area is smaller than the height K from the center of the pipe 500 to the interface (S319: No), θ may be uniformly set to 90 ° (S312).

  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 (S313).

  When the area of the target region is calculated, a corresponding flow velocity is set (S314). As described above, when there is a flow velocity profile corresponding to the target region, the flow velocity is used for the flow rate calculation, and when there is no flow velocity profile corresponding to the target region, the lower half region on the same circumference of the region. The flow rate of the flow rate profile corresponding to is used for the flow rate calculation.

  Then, the flow rate of the target region is calculated by multiplying the area of the target region by the set flow velocity (S315).

  The above process for calculating the flow rate of the target area is repeated for the entire upper half area (S316). When the process of calculating the flow rate is performed on the entire upper half region (S316: Yes), the flow rates of the lower half and upper half regions are summed (S317). Thereby, the flow rate of the lowest layer is calculated (S203).

<Top layer flow rate calculation>
Next, the uppermost layer flow rate calculation (S205) will be described. FIG. 12 is a flowchart showing the procedure of the uppermost layer flow rate calculation (S205). In the uppermost layer flow rate calculation, it is only necessary to perform processing that is inverted upside down from the most downstream flow rate calculation. That is, the case is divided according to whether the lower interface position of the uppermost layer is below the center of the pipe 500 (S401).

  If the interface position of the uppermost layer is greater than or equal to the center of the pipe 500 (S401: Yes), the area of each semicircular region with the lower part cut off is calculated for each integral width, and the total is multiplied by the corresponding flow velocity. do it.

  Therefore, a target area whose area is calculated in a predetermined order is set (S402). Then, from the radius R and the height Hh of the target area, an angle θ that is half the central angle of the target area is calculated (S403). Here, the radius R is a fan-shaped radius with the outer periphery of the target region as an arc, and the height Hh is the distance from the interface of the target region to the top of the outer periphery. At this time, since cos θ = (R−Hh) / 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 distance from the interface to the pipe apex.

  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 (S404). The flow rate in the target area is calculated by multiplying the flow velocity of the section corresponding to this area (S405).

  The above process for calculating the flow rate of the target area is repeated for the entire upper half area (S406).

  When the process of calculating the flow rate is performed on all the upper half regions (S406: Yes), the flow rates of the respective regions are summed (S407).

  When the lower interface position of the uppermost layer is not more than the center of the pipe 500 (S401: No), the upper half region is integrated by the same procedure as the conventional one (S408). The lower half integration is performed as follows.

  First, a target area is set in the lower half (S409). Then, it is determined whether or not the radius R of the target region is larger than the height K from the interface to the center of the pipe 500 (S410). Here, when the radius R of the target region is larger than the height K from the interface to the center of the pipe 500, the lower part of the target region 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 interface to the center of the pipe 500, the target area does not intersect the interface and remains in a semicircular arc shape.

  When the radius R of the target area is larger than the height K from the interface to the center of the pipe 500 (S410: Yes), one area of the target area is calculated from the radius R and the height K from the interface to the center of the pipe 500. Is calculated (S411).

  On the other hand, when the radius R of the target region is smaller than the height K from the interface to the center of the pipe 500 (S319: No), θ may be uniformly set to 90 ° (S412).

  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 (S413).

  When the area of the target region is calculated, a corresponding flow velocity is set (S414). If there is a flow velocity profile corresponding to the target area, the flow velocity is used for the flow rate calculation. If there is no flow velocity profile corresponding to the target area, the flow velocity profile corresponding to the upper half area on the same circumference of the area. Is used for the flow rate calculation.

  Then, the flow rate of the target region is calculated by multiplying the area of the target region by the set flow velocity (S415).

  The above process for calculating the flow rate of the target area is repeated for all the lower half areas (S416). When the process of calculating the flow rate is performed for the entire lower half region (S416: Yes), the flow rates of the lower half region and the upper half region are summed (S417). Thereby, the flow rate of the uppermost layer is calculated (S205).

<Intermediate layer flow calculation>
Next, the intermediate layer flow rate calculation (S206) will be described. 13 and 14 are flowcharts showing the procedure of the intermediate layer flow rate calculation (S206). In the intermediate layer flow rate calculation, cases are classified according to whether the calculation target intermediate layer straddles the center of the pipe 500, that is, whether the pipe center 500 is between the upper interface and the lower interface of the intermediate layer (S501).

  As shown in FIG. 15A, when the intermediate layer straddles the center of the pipe 500 (S501: Yes), as shown in the hatched area of FIG. The area of each region can be calculated and multiplied by the corresponding flow velocity to be totaled.

  However, there is a case where the flow velocity profile of the calculation target layer does not exist and the other flow velocity profile on the same circumference does not exist like the black region in FIG. In this case, as shown in FIG. 15B, the flow velocity profile curve of that layer is interpolated to determine the flow velocity. The flow velocity profile curve can be interpolated, for example, by approximating the curve near the interface as the interpolation use range. At this time, it is desirable that the interpolation use range does not straddle the pipe center.

  If the flow velocity profile of the layer to be calculated does not exist and the other flow velocity profile on the same circumference exists, the other flow velocity profile may be used.

  Therefore, first, a target region for calculating the flow rate in a predetermined order is set for the lower half (S502). The area calculation of the lower half target area is the same as the area calculation of the lower half target area when the interface in the uppermost layer flow rate calculation (S205) is below the center of the pipe 500, except when the flow velocity profile is interpolated. is there.

  That is, the target area is set in the lower half (S502), and it is determined whether the radius R of the target area is larger than the height K from the interface to the center of the pipe 500 (S503).

  When the radius R of the target area is larger than the height K from the interface to the center of the pipe 500 (S503: Yes), one area of the target area is calculated from the radius R and the height K from the interface to the center of the pipe 500. Is calculated (S504). On the other hand, when the radius R of the target region is smaller than the height K from the interface to the center of the pipe 500 (S503: No), θ may be uniformly set to 90 ° (S505).

  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 (S506).

  When the area of the target region is calculated, a corresponding flow velocity is set (S507). If there is a flow velocity profile corresponding to the target area, the flow velocity is used for the flow rate calculation. If there is no flow velocity profile corresponding to the target area, the flow velocity profile corresponding to the upper half area on the same circumference of the area. If there is a flow velocity profile, the flow velocity is used for the flow rate calculation.If there is no flow velocity profile corresponding to the upper half region on the same circumference of the region, the flow velocity obtained by interpolating the flow velocity profile of the calculation target layer is used for the flow rate calculation. Shall be used.

  Then, the flow rate of the target region is calculated by multiplying the area of the target region by the set flow velocity (S508). The above process for calculating the flow rate of the target area is repeated for all the lower half areas (S509).

  Next, a target region whose area is calculated in a predetermined order for the upper half is set (S510). The area calculation of the upper half target area is the same as the area calculation of the upper half target area when the interface in the lowermost flow rate calculation (S203) is equal to or greater than the center of the pipe 500, except when the flow velocity profile is interpolated. is there.

  That is, the target area is set in the upper half (S510), and it is determined whether the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface (S511).

  When the radius R of the target area is larger than the height K from the center of the pipe 500 to the interface (S511: 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 (S512). On the other hand, if the radius R of the target region is smaller than the height K from the center of the pipe 500 to the interface (S511: No), θ may be uniformly set to 90 ° (S513).

  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 (S514).

  When the area of the target region is calculated, a corresponding flow velocity is set (S515). If there is a flow velocity profile corresponding to the target area, the flow velocity is used for the flow rate calculation. If there is no flow velocity profile corresponding to the target area, the flow velocity profile corresponding to the lower half area on the same circumference of the area. If there is a flow velocity profile, the flow velocity is used for the flow rate calculation.If there is no flow velocity profile corresponding to the lower half region on the same circumference of the region, the flow velocity obtained by interpolating the flow velocity profile of the calculation target layer is used for the flow rate calculation. Shall be used.

  Then, the flow rate of the target region is calculated by multiplying the area of the target region by the set flow velocity (S516). The above process for calculating the flow rate of the target area is repeated for the entire upper half area (S517).

  When the flow rate in each region in the lower half and the flow rate in each region in the upper half are calculated, the flow rates in each region in the lower half and the upper half are summed (S518). Thereby, the flow rate of the intermediate layer when the upper interface and the lower interface straddle the center of the pipe 500 (S501: Yes) is calculated.

  As shown in FIG. 16 (a), when the intermediate layer to be calculated does not straddle the center of the pipe 500 (S501: No), FIG. 16 (b) for each integration layer in the lower half or upper half region. The area of the region as shown in FIG. The area of the region shown in FIG. 16 (b) is from the area of the region from the center of the pipe as shown in FIG. 16 (c) to the interface near from the center of the pipe as shown in FIG. 16 (d). It can be obtained by subtracting the area of the region.

  Therefore, as shown in the flowchart of FIG. 14, when the target region is set (S601), the area from the center of the pipe 500 to the lower interface is calculated (S602). This area corresponds to the area shown in FIG.

  If the target area is the lower half, it is the same as the calculation of the area of the lower half target area when the interface in the uppermost layer flow rate calculation (S205) is below the center of the pipe 500. If the target area is the upper half, This is the same as the calculation of the area of the upper half target region when the interface in the lowest layer flow rate calculation (S203) is equal to or greater than the center of the pipe 500.

  Further, the area from the center of the pipe 500 to the upper interface is calculated (S603). This area corresponds to the area shown in FIG. If the target area is the lower half, it is the same as the calculation of the area of the lower half target area when the interface in the uppermost layer flow rate calculation (S205) is below the center of the pipe 500. If the target area is the upper half, This is the same as the calculation of the area of the upper half target region when the interface in the lowest layer flow rate calculation (S203) is equal to or greater than the center of the pipe 500.

  Then, the area of the target region is calculated from the area from the center of the pipe 500 to the lower interface and the area from the center of the pipe 500 to the upper interface (S604). If the target area is the lower half, the latter should be subtracted from the former, and if the target area is the upper half, the former should be subtracted from the latter.

  When the area of the target region is calculated, a corresponding flow velocity is set (S605). If there is a flow velocity profile corresponding to the target region, that flow velocity is used for flow rate calculation.If there is no flow velocity profile corresponding to the target region, the flow velocity obtained by interpolating the flow velocity profile of the calculation target layer is used as the flow rate. It shall be used for calculation.

  Then, the flow rate of the target region is calculated by multiplying the area of the target region by the set flow velocity (S606). The above process for calculating the flow rate of the target area is repeated for all areas (S607).

  When the flow rate of each region is calculated, the flow rate of each region is summed (S608). Accordingly, the flow rate of the intermediate layer when the intermediate layer does not straddle the center of the pipe 500 (S501: No) is calculated. The first example of the present embodiment has been described above.

<Second embodiment>
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. The flow rate can be measured for each layer even if the uppermost layer is a gas in a multiphase flow, that is, a non-full water multiphase flow or a single layer flow.

  FIG. 17 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 a single laminar flow or a multiphase flow. Further, the pipe 500 may be fully filled, or it may be a non-full state having a space in the upper part. In the example of this figure, the fluid F1 and the fluid F2 form a layer, and further, an air layer exists above the fluid F2 and is in a non-full state.

  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 generation unit 130, a reflected signal intensity profile generation 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 (S701). In various settings, the inner diameter of the pipe 500, the mounting angles of the ultrasonic sensors 210 and 210a, and other parameters are set.

  In the second embodiment, measurement is first performed by the lower ultrasonic sensor 210 and the upper ultrasonic sensor 210a by either the pulse Doppler method or the reflection correlation method (S702). The lower ultrasonic sensor 210 may be measured in the same manner as in the first embodiment, and the upper ultrasonic sensor 210a may be confirmed to be able to receive an echo wave.

  Then, based on the measurement result, full / non-full water is determined (S703). Specifically, when both the lower ultrasonic sensor 210 and the upper ultrasonic sensor 210a receive an echo wave, it is determined that the water is full and the lower ultrasonic sensor 210 alone receives the echo wave. When it is determined that the water is not full. When neither the lower ultrasonic sensor 210 nor the upper ultrasonic sensor 210a receives an echo wave, the pipe 500 may be determined to be empty.

  Further, the number of layers is determined based on the reflected signal intensity profile obtained by the measurement (S704). The number of layers can be determined in the same manner as in the first embodiment.

  As a result, when the inside of the pipe 500 is full and is a single layer flow (S705: Yes), measurement using the propagation time difference method is executed (S706). This is because if the fluid F to be measured is full and is a single layer flow, high accuracy can be obtained by measurement using the propagation time difference method. In the measurement using the propagation time difference method, ultrasonic signals were alternately transmitted and received by the ultrasonic sensors 210 and 210a, the respective propagation times were measured, and the flow rate was calculated by the propagation time difference method (S707). The flow rate is output as a measurement result (S709).

  On the other hand, when it is not full or when it is a multiphase flow (S705: No), the flow rate measurement shown in the first embodiment is performed. That is, the flow rate calculation based on the flow velocity profile and the received signal strength profile already acquired in the processing (S702) is executed (S708), and the obtained flow rate is output as a measurement result (S709).

  In the non-full state, the uppermost layer flow rate calculation (S203) in the first embodiment can be omitted because it can be handled as a multiphase flow with the gas layer as the uppermost layer.

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

Claims (7)

An ultrasonic flowmeter that emits an ultrasonic pulse into a pipe through which a fluid to be measured flows and generates a flow velocity profile based on a reflection signal from an ultrasonic reflector included in the fluid to be measured,
A reflected signal intensity profile generator that generates a reflected signal intensity profile based on the received intensity of the reflected signal;
An interface determination unit that identifies the number of interfaces and the position of each interface based on the reflected signal intensity profile;
A flow rate calculation unit that calculates the flow rate of the fluid to be measured for each layer divided by the interface based on the flow velocity profile and the interface position;
An ultrasonic flowmeter comprising:   2. The ultrasonic flowmeter according to claim 1, wherein the interface determination unit determines that a maximum position of a reflection signal intensity in the reflection signal intensity profile that is equal to or greater than a predetermined reference is an interface.   The flow rate calculation unit divides the inside of the pipe into concentric semicircular regions, and for each region obtained by multiplying the area of the region included in the flow rate calculation target layer by the flow velocity determined based on the flow velocity profile. The ultrasonic flowmeter according to claim 1, wherein the flow rate for each layer of the fluid to be measured is calculated by summing the flow rates. The flow velocity determined based on the flow velocity profile applies the flow velocity profile when a flow velocity profile corresponding to the region exists,
If there is no flow velocity profile corresponding to that region, and there is a flow velocity profile corresponding to another region on the same circumference of that region, apply that flow velocity profile,
If there is no flow velocity profile corresponding to that region, and there is no flow velocity profile corresponding to other regions on the same circumference of the region, the flow velocity profile obtained by interpolating the flow velocity profile of the layer should be applied. The ultrasonic flowmeter according to claim 3, wherein   The ultrasonic wave according to any one of claims 1 to 4, wherein a full / non-full state of the pipe is determined based on a reflection signal of an ultrasonic pulse emitted from an opposing position of the pipe. Flowmeter.   The ultrasonic flowmeter according to claim 5, wherein the flow rate calculation unit treats the space between the gas layer and the fluid to be measured as an interface when it is determined that the pipe is not full.   6. The method according to claim 5, further comprising a measurement method control unit that switches to perform flow rate measurement by a propagation time difference method when the pipe is determined to be full and the number of interfaces is determined to be zero. 6. The ultrasonic flowmeter according to 6.