WO2005064286A1

WO2005064286A1 - Ultrasonic flow meter

Info

Publication number: WO2005064286A1
Application number: PCT/JP2004/019431
Authority: WO
Inventors: Michitsugu Mori; Kenichi Tezuka; Hideaki Tezuka
Original assignee: The Tokyo Electric Power Company, Incorporated
Priority date: 2003-12-26
Filing date: 2004-12-24
Publication date: 2005-07-14
Also published as: JPWO2005064286A1

Abstract

[OBJECT] To accurately measure a flow by reducing a measurement error resulting from reflected wave from a pipe. [CONSTITUTION] This ultrasonic flow meter comprises an ultrasonic transmission means (20) letting ultrasonic pulses of a specified frequency from an ultrasonic transducer into a measured flow (11) in a fluid pipe (10) along a measurement line, a fluid velocity distribution measurement means (20) receiving ultrasonic echo (reflected wave A) reflected from a measurement area among the ultrasonic pulses let in the measured fluid (11) and measuring the flow velocity distribution of the measured fluid (11) in the measurement area, and a flow calculation means calculating the flow of the measured fluid in the measurement area based on the flow velocity distribution of the measured fluid (11). A sound absorbing material (40) is installed on the inner wall of the fluid pipe (10) for the measured fluid (11), and the material of the sound absorbing material is a highly dense material such that the acoustic impedance of the sound absorbing material (40) is approximate to the acoustic impedance of the fluid pipe (10). The inner wall of the fluid pipe (10) including the sound absorbing material (40) is formed to be uniformized.

Description

Specification

Ultrasonic flow meter

Technical field

The present invention relates to an ultrasonic flowmeter capable of instantaneously measuring the flow rate of a fluid to be measured from a flow velocity distribution in a measurement region in a time-dependent manner, and a technique related thereto. Background art

[0002] Various technologies are provided for a Doppler ultrasonic flowmeter capable of measuring a flow rate without contact. (For example, JP-A-2000-97742)

[0003] Patent Document 1: JP-A-2000-97742

[0004] The above technique will be specifically described. The Doppler type ultrasonic flow meter disclosed in the above-mentioned document causes an ultrasonic pulse of a required frequency to be incident on a fluid to be measured in a fluid (for example, water) pipe along an ultrasonic transducer force measurement line. An ultrasonic transmitting means, and a fluid velocity distribution for receiving an ultrasonic echo reflected from the measurement area among the ultrasonic pulses incident on the measurement fluid, and measuring a flow velocity distribution of the fluid to be measured in the measurement area. The flow rate of the fluid to be measured is measured by providing a measuring means and a flow rate calculating means for calculating the flow rate of the fluid to be measured in the measurement area based on the flow velocity distribution of the fluid to be measured.

[0005] This technique measures the flow velocity distribution of a fluid to be measured flowing in a pipe, and has excellent responsiveness to a transient flow rate that varies with time. Also, where the fluid flow is not sufficiently developed or the flow becomes three-dimensional! /, It may be damaged even immediately after a bent pipe such as an elbow pipe or a U-shaped inverted pipe. The flow rate of the measurement fluid can be measured efficiently, accurately and instantaneously. Compared with the ultrasonic flowmeters provided before that, accurate measurement is possible without the `` flow rate correction coefficient '' calculated from experimental or empirical values. , Has been greatly appreciated.

[0006] By the way, pipes are likely to corrode! / When flowing fluid (for example, seawater or various kinds of wastewater), in order to prevent corrosion, pipes made of a corrosion-resistant material are used. A technique called “lining” is used to weld a pipe made of a corrosion-resistant material such as glass flake to the inner wall of a steel pipe. The thickness of the lining depends on the type of piping, fluid, and speed. The force varies depending on the conditions. Generally, 7 to 10 mm is large.

Disclosure of the invention

Problems to be solved by the invention

[0007] Now, with the aim of further improving the measurement accuracy of the above-mentioned Dobler ultrasonic flowmeter, the following problems have surfaced.

This will be described with reference to FIGS. As the ultrasonic wave transmitted by the ultrasonic wave transmitting means, it is desirable to use only the reflected wave that has been reflected normally to bubbles in the fluid to be measured (“reflected wave A” shown in FIGS. 5 and 6). As shown in Fig. 5, the transmitted ultrasonic wave reaches the fluid pipe 10, and the reflected wave from the fluid pipe 10 ("reflected wave B" in Fig. 5) hits another bubble and is reflected. By following the same path as A, the ultrasonic transmission / reception means 20 received the signal, which proved to be a cause of measurement error.

[0008] Further, as shown in FIG. 6, when an ultrasonic wave enters the fluid pipe 10, the reflected wave propagates through the fluid pipe 10 without entering the non-measurement fluid 11 and then enters the fluid 11 to be measured. Thereafter, it was found that a measurement error was caused by the ultrasonic wave transmitting and receiving means 20 receiving and measuring the reflected wave B after being hit against the air bubble and reflected.

Although not shown, if the flow velocity distribution of the measured fluid can be measured only by the reflected waves reflected by bubbles or the like in the measured fluid, the measurement result should theoretically draw a parabola. However, in the actual measurement result, a flat linear part is drawn near the top of the parabola.

[0010] The above-described problem has similarly occurred in lining pipes. This is because materials such as polyethylene and glass flake cannot absorb the presence of reflected wave B.

[0011] The problem to be solved by the present invention is to provide a technique for reducing the measurement error caused by the reflected wave from the pipe and measuring the flow rate more accurately.

An object of the invention described in claims 1 to 3 is to provide an ultrasonic flowmeter for measuring a flow rate more accurately by reducing a measurement error caused by a reflected wave of piping force. Means for solving the problem

[0012] (Claim 1) The invention according to claim 1 is an ultrasonic transmission means for injecting an ultrasonic pulse of a required frequency from an ultrasonic transducer into a measured fluid (11) in a fluid pipe (10) along a measurement line (20) Of the ultrasonic pulse incident on the fluid under measurement (11), receives the ultrasonic echo (reflected wave A) reflected from the measurement area, and measures the flow velocity distribution of the fluid under measurement (11) in the measurement area A fluid velocity distribution measuring means (20); and a flow rate calculating means for calculating a flow rate of the fluid to be measured in the measurement area based on a flow velocity distribution of the fluid to be measured (11). To an ultrasonic flowmeter.

Then, on the inner wall of the fluid pipe (11) near where the ultrasonic transmission means (20) is fixed to the fluid pipe (10) of the fluid to be measured (11), the acoustic impedance of the fluid pipe (10) is approximated. It is characterized by including a high-density sound absorbing material (40) having an acoustic impedance of a value.

[0013] The above ultrasonic flowmeter includes a general Dobler ultrasonic flowmeter and an ultrasonic flowmeter using a correlation method. The ultrasonic flow meter using the correlation method is, for example, an ultrasonic flow meter disclosed in JP-A-2003-344131.

In both cases, the ultrasonic transmitting means for injecting the ultrasonic pulse of the required frequency along the measuring line into the fluid to be measured in the fluid pipe, and the ultrasonic wave transmitted to the fluid to be measured A fluid velocity distribution measuring means for receiving the reflected ultrasonic echo of the measurement area force of the sound wave pulse and measuring the flow velocity distribution of the fluid to be measured in the measurement area; based on the flow velocity distribution of the fluid to be measured, And a flow rate calculating means for calculating a flow rate of the fluid to be measured in the measurement area.

[0014] (Glossary)

"Flow rate calculation means" is, when the flow rate is m (t),

[Number 1]

m (t) = p Cv (x-t)-dA (1) where / O is the density of the measured flow rate

V (x · t): Means for calculating the velocity component (X direction) at time t. [0015] From the above equation (1), the flow rate m (t) at the time t flowing through the fluid pipe can be rewritten as the following equation.

[Equation 2] m (t) = pjjvx (r · θ · ή · r · dr · ίΐθ …… (2) where vx (r. 0 · t) is the distance r from the center on the pipe cross section at time t , Velocity component in the direction of the tube axis at angle 0

[0016] The flow of the fluid to be measured flowing in the pipe is a flow in the pipe axis direction, which is radial or angular.

Assuming that the flow Θ of Θ, vr, V 無視 can be ignored, vx>> vr = v 、, and the flow measurement is simplified and expressed by the following equation.

[Equation 3] m {t) = · one J {vx (r · θΐ · r / sin ce} 'r-dr …… (3) Here, one is the super The angle of incidence of the sound wave, that is, the angle made with respect to the perpendicular to the tube wall.

[0017] "The inner wall of the fluid pipe (10) in the vicinity of fixing the ultrasonic transmission means (20) to the fluid pipe (10) of the fluid to be measured (11) provided with the sound absorbing material (40)" The variable position is defined by variable conditions such as the angle of incidence of the ultrasonic wave transmitted from the ultrasonic transducer (20), the material of the pipe, the inner or outer diameter or wall thickness of the pipe, and the type of the fluid to be measured. Specified by being specified. For example, in the case of the inner wall of the pipe on the opposite side across the fluid to be measured (11) (for example, Fig. 1), the case of the inner wall of the pipe on the incident side of the ultrasonic transducer (20) where ultrasonic force is also transmitted (for example, Fig. 2) and so on.

Note that the inner wall of all the fluid pipes (10) in which the variable condition force can be derived may be covered with a sound absorbing material (40) in advance.

According to the acoustic impedance of the sound-absorbing material, “a high-density material that approximates the acoustic impedance of the fluid pipe” is used because otherwise, an ultrasonic wave would be generated at the interface between the sound-absorbing material and the pipe. Is reflected. As a specific material, it is formed by mixing a high-density metal powder (for example, fine tungsten powder) with a synthetic resin (for example, epoxy resin). Was preferred. As the high-density metal, chromium, molybdenum, and the like can also be used.

The “acoustic impedance and approximate value of the fluid piping” is, for example, about ± 15%, preferably about ± 10%, and more preferably about ± 5%.

[0019] When the invention according to the present claim is applied to existing piping equipment, if lining has been applied in advance, the lining is performed as follows. In other words, the work procedure involves cutting a portion where the sound absorbing material (40) is required, embedding the sound absorbing material (40), and performing a process of smoothing the surface (the inner wall surface of the pipe for the fluid).

[0020] (Action)

First, an ultrasonic pulse of a required frequency is incident on the fluid to be measured (11) in the fluid pipe (10) along the ultrasonic transducer (20) force measurement line. Then, of the ultrasonic pulses incident on the fluid to be measured (11), those that also reflected the force in the measurement area (“reflected wave A” in Fig. 1) became the measurement target, and the reflected ultrasonic waves Part of the pulse (“ultrasonic wave C” in FIG. 1) reaches the fluid pipe (10) of the fluid to be measured (11). However, the sound absorbing material (40) is fixed to the pipe outer wall at the arrival position, and the acoustic impedance of the sound absorbing material (40) is high enough to approximate the acoustic impedance of the fluid pipe (10). Most of the material is absorbed. Therefore, it is possible to prevent the reflected wave from the fluid pipe (10) from becoming a measurement target and causing a measurement error.

Fluid velocity distribution measuring means (The ultrasonic transducer (20) receives the ultrasonic echo and measures the flow velocity distribution of the fluid to be measured (11) in the measurement area. The flow rate calculating means calculates the flow rate of the fluid to be measured (11) in the measurement area based on the distribution.

[0021] (Claim 2)

The invention according to claim 2 relates to an ultrasonic flowmeter provided with a flange and a pipe connected to a fluid pipe related to a fluid to be measured and fixed between the fluid pipes related to the fluid to be measured.

That is, a partial pipe (15) having the same inner diameter as the fluid pipe (10), Flanges (16, 16) for fixing (15) to the fluid pipe (10) related to the fluid to be measured (11) and the ultrasonic pulse of the required frequency fixed to the partial pipe (15) and An ultrasonic transmission means (20) for injecting the ultrasonic wave from the ultrasonic transducer along the measurement line into the fluid to be measured in the fluid pipe. In addition, the inner wall of the partial pipe (15), to which the ultrasonic wave incident by the ultrasonic wave transmitting means (20) reaches, has an acoustic impedance that approximates the acoustic impedance of the fluid pipe (10). Equipped with high-density sound absorbing material (40).

Further, the ultrasonic transmitting means (20) receives the ultrasonic echo reflected from the measurement region force among the ultrasonic pulses incident on the fluid to be measured (11), and detects the velocity of the fluid to be measured in the measurement region. Fluid velocity distribution measuring means for measuring the distribution, and flow rate calculating means for calculating the flow rate of the fluid to be measured in the measurement area based on the flow rate distribution of the fluid to be measured. .

(Action)

The ultrasonic flowmeter according to the present invention is mounted in the middle of the fluid pipe (10) of the fluid to be measured whose flow rate is to be measured, using the flanges (16, 16). Since the installed ultrasonic flowmeter has the same partial pipe (15) as the inside diameter of the fluid pipe (10) to be measured, the inner wall is continuous, and it is not possible to change the flow of the fluid (11) to be measured. Absent.

An ultrasonic pulse of a required frequency is injected along the ultrasonic transducer (20) force measurement line into the fluid to be measured (11) in the fluid pipe (10). Then, of the ultrasonic pulses incident on the fluid to be measured (11), those reflected from the measurement area (reflected wave A) are to be measured, and a part of the ultrasonic pulse is the fluid of the fluid to be measured (11). It reaches the pipe (10) and reflects inside the fluid pipe (10) without reaching the fluid to be measured (11). However, a sound-absorbing material (40) is fixed to the inner wall of the pipe at the arrival position, and the acoustic impedance of the sound-absorbing material (40) is high-density so as to approximate the acoustic impedance of the fluid pipe (10). Mostly absorbed because of the material. Therefore, it is possible to prevent the reflected wave from the fluid pipe (10) from being a measurement target and causing a measurement error.

The ultrasonic transducer (20) receives the ultrasonic echo, and the fluid velocity distribution measuring means connected to the ultrasonic transducer (20) measures the flow velocity distribution of the fluid to be measured (11) in the measurement area. I do. Then, based on the flow velocity distribution of the fluid to be measured (11), the measurement area Is calculated by the flow rate calculating means.

(Claim 3)

The invention according to claim 3 limits the ultrasonic flowmeter according to claim 1 or 2.

That is, the sound absorbing material (40) is provided integrally with a liner provided inside the pipe (10).

[0024] (Action)

In order to integrally form the sound absorbing material (40) and the liner, for example, the following method is used. In the case of the pipe (10) which has been lining in advance, the part where the sound absorbing material (40) is required is cut, and the sound absorbing material (40) is installed integrally with the lining at the cut part. Thus, the inner surface formed by the sound absorbing (40) is flush with the inner wall surface in the liner portion. Therefore, the flow velocity of the fluid to be measured does not change due to the presence of the sound absorbing material (40).

(Claim 4)

The invention described in claim 4 limits the invention described in any one of claims 1 to 3.

That is, it is assumed that the acoustic impedance of the sound absorbing material (40) is a high-density material that approximates the acoustic impedance of the fluid pipe (10).

“Acoustic impedance and approximate value of fluid piping” is, for example, about ± 15%, preferably about ± 10%, and more preferably about ± 5%.

More specifically, it is formed of a material formed by mixing a high-density metal powder with a synthetic resin. This allows most reflected waves to be absorbed even if the thickness is about 5-15 mm. Due to this thickness dimension, the inner wall of the pipe can be made flush even when adopted for lining pipes.

According to the inventions set forth in claims 1 to 3, there is provided an ultrasonic flowmeter for reducing a measurement error caused by a reflected wave from a pipe and measuring a more accurate flow rate. Was able to BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail based on embodiments and drawings. The drawings used here are FIGS. 1 to 4.

(Figure 1)

FIG. 1 shows an ultrasonic flowmeter for measuring a flow rate of a fluid pipe 10 through which a fluid 11 to be measured flows, and an ultrasonic echo reflected from a measurement area of an ultrasonic pulse incident on the fluid 11 to be measured. An ultrasonic transmission / reception means (transducer 20) also serving as a receiver for receiving the signal. The transducer 20 is fixed to a predetermined portion of the pipe 10 with a resin wedge 30. The material of the wedge 30 is, for example, epoxy resin.

[0029] Transducer 20 includes an ultrasonic transmission unit that transmits an ultrasonic pulse of a required frequency (fundamental frequency) to measurement target fluid 11 along a measurement line, and an ultrasonic pulse incident on measurement target fluid. Measurement area force Receives the reflected ultrasonic echo and also serves as a fluid velocity distribution measuring means for measuring the flow velocity distribution of the fluid to be measured in the measurement area! A computer, such as a microcomputer, CPU, or MPU, serving as a flow rate calculating means for obtaining the flow rate of the fluid to be measured in a time-dependent manner based on the flow velocity distribution, and a display device capable of displaying the output from the computer in a time-series manner And connected to.

Further, the transducer 20 is provided with a vibrating amplifier as a signal generator for vibrating the transducer 20, and a pulse electric signal of a required fundamental frequency is generated by the vibrating amplifier. The signal is input to a sound wave transducer. Then, an ultrasonic pulse of the fundamental frequency is transmitted along the measurement line by application of the pulse electric signal. The ultrasonic pulse is a straight beam with a pulse width of about 5 mm and almost no spread!

The transducer 20 is configured to receive an ultrasonic echo (reflected wave A) transmitted and reflected by the reflector 12 in the fluid 11. Here, the reflector 12 is a gas bubble uniformly contained in the fluid 11 to be measured. Basically, the fluid to be measured 11 must be a foreign substance having a different acoustic impedance.

[0032] The ultrasonic echo received by the transducer 20 is received by a reflected wave receiver (not shown), and is converted into an echo electric signal by the reflected wave receiver. this The echo electric signal is amplified by an amplifier and then digitally converted through an AD converter. Then, the digitized digital echo signal is input to a flow velocity calculator provided with a flow velocity distribution measuring circuit.

An electric signal of the fundamental frequency from the transmitting amplifier is digitized and input to the flow velocity calculator, and the flow velocity is measured using the change in the flow velocity based on the Doppler shift of the two signals or the cross-correlation value of the two signals. Then, the flow velocity distribution in the measurement area along the measurement line is calculated. By calibrating the flow velocity distribution in the measurement area with the incident angle α of the ultrasonic wave, the flow velocity distribution in the cross section of the fluid pipe can be measured.

[0033] If the dimensions of the fluid pipe 10 (two or more of outer diameter, wall thickness, and inner diameter), the material of the fluid pipe 10 and the type of the fluid 11 are known in advance, The incident angle α of the sound wave can be specified. In such a case, the wedge 30 can be omitted to obtain a “wetted type”.

[0034] When the incident angle oc of the ultrasonic wave by the transducer 20 is determined and variable conditions such as the material of the pipe, the inner diameter and outer diameter or wall thickness of the pipe, and the type of the fluid to be measured are specified, the sound absorption The position of the inner wall in the fluid pipe 10 where the material 40 is to be provided is determined. The sound absorbing material supporter 41 arranges and fixes the sound absorbing material 40 so that the sound absorbing material 40 is located at that position. The thickness of the sound absorbing material 40 is 7 to 15 mm. Also, since the ultrasonic pulse is a straight beam with a pulse width of about 5 mm and almost no spread, if the variable conditions are specified, the sound absorbing material 40 has a diameter of about 10 to 20 mm. If it is enough.

Note that the inner surface formed by the sound absorbing material 40 and the sound absorbing material supporter 41 is formed so as to be flush with the inner wall surface of the fluid pipe 10 where they do not exist, so that the flow velocity does not change.

[0035] The material of the above-mentioned "sound absorbing material supporter 41" is a case where the liquid flowing through the pipe 10 is a liquid (for example, seawater or various kinds of wastewater) that corrodes steel pipes, and employs a lining. In this case, the material used for the lining (polyethylene, glass flake) is used. Even when piping made of a corrosion-resistant material is used, the material of the “sound absorbing material supporter 41” is desirably a material that does not corrode with the liquid.

In the case of piping 10 that has been lined in advance, Cutting is performed, and a sound absorbing material is installed integrally with the lining at the cut portion. Thus, the inner surface formed by the sound absorbing material 40 is flush with the inner wall surface in the liner portion, and the flow velocity does not change.

The acoustic impedance of the above-described sound absorbing material 40 is a high-density material having a similar value to the acoustic impedance of the fluid pipe 10. More specifically, it is a material formed by mixing a high-density metal powder (tungsten powder) with a synthetic resin (epoxy resin). Due to the presence of the sound absorbing material 40, it is possible to suppress the reflected waves generated by the ultrasonic waves C not reflected by the bubbles 12 in the fluid reflected on the inner wall of the fluid pipe 10. Therefore, it is possible to suppress the reflected wave from the fluid pipe 10 from becoming a measurement target and causing a measurement error.

The material of the sound absorbing material is not limited to a material formed by mixing tungsten powder with epoxy resin, but may be any material having a high density that approximates the acoustic impedance of the fluid pipe 10, such as tungsten. Alternatively, lead or molybdenum can be used.

[0037] The reflected wave received by the receiver of the trans- ducer 20 is amplified by an amplifier (not shown) and then digitally converted through an AD converter. Then, the sound speed calculation device calculates the sound speed using the digital echo signal that has been digitally converted. The calculated sound speed is output to the ultrasonic flow meter and used to calculate the flow rate, flow velocity distribution, and the like in real time.

[0038] It is assumed that a part of the ultrasonic pulse that is not reflected in the measurement area has reached the fluid pipe of the fluid to be measured and has been reflected, causing a situation that is considered to have caused a measurement error. In this case, it is considered that the fixing position of the sound absorbing material 40 with respect to the pipe outer wall is not appropriate, so the arrangement of the sound absorbing material 40 and the sound absorbing material supporter 41 is reviewed. For example, measures such as moving the sound absorbing material 40 to an appropriate position, increasing the number of fixed portions of the sound absorbing material 40, or changing the irradiation angle of the transducer 20 to the fluid pipe 10 are taken.

When the sound absorbing material 40 and the sound absorbing material supporter 41 were arranged at appropriate positions, no measurement error due to the ultrasonic waves C that were reflected by the bubbles 12 in the fluid could not be confirmed.

[0039] (Fig. 2)

The embodiment shown in FIG. 2 includes a fluid distribution among the ultrasonic waves transmitted from the transducer 20. The reflected wave E generated by being reflected on the inner wall of the fluid pipe 10 without being transmitted to the inside of the non-measuring fluid 11 through the pipe 10 does not enter the inside of the non-measuring fluid 11 so that the reflected wave E The sound absorbing material 40 is arranged at the reaching position. The inner surface force formed by the sound absorbing material 40 and the sound absorbing material supporter 41 is formed so as to be flush with the inner wall surface of the fluid pipe 10 where they do not exist, and the flow velocity does not change. This is the same as the embodiment shown in FIG.

[0040] (Fig. 3)

The third embodiment shown in FIG. 3 is an ultrasonic flowmeter with a flange formed so as to be mountable using flanges 16 and 16 in the middle of a fluid pipe 10 for a fluid to be measured whose flow rate is to be measured.

That is, a partial pipe 15 having the same inner diameter as the fluid pipe 10 of the fluid to be measured whose flow rate is to be measured, and flanges 16 for fixing the partial pipe 15 to the fluid pipe 10 of the fluid to be measured 11 And an ultrasonic transmission means 20 fixed to the partial pipe 15 and for causing an ultrasonic pulse of a required frequency to be incident on the fluid to be measured in the fluid pipe along the ultrasonic transducer force measurement line. Puru.

[0041] The inner surface formed by the sound absorbing material 40 and the sound absorbing material supporter 41 in the partial pipe 15 needs to be formed so as to be flush with the inner wall surface of the fluid pipe 10 related to the fluid to be measured whose flow rate is to be measured. is there. In the attached ultrasonic flow meter, the partial pipe 15 has the same inner diameter as the fluid pipe 10 to be measured, so that the inner wall is continuous and the flow of the fluid to be measured 11 does not change.

The transducers 20 are fixed with wedges 30 as shown in the figure, and the variable conditions such as the pipe material, the pipe inner diameter and outer diameter or wall thickness, and the type of the fluid to be measured can be specified. In such a case, it may be provided as a wetted type.

[0042] (FIG. 4)

The embodiment shown in FIG. 4 is a combination of the embodiments shown in FIGS. 1 and 2. That is, the sound absorbing material 40 for the ultrasonic waves C reaching the inner wall surface of the fluid pipe 10 on the opposite side to the transducer 20 and the sound absorbing material E for the reflected wave E generated by reflecting on the inner wall of the fluid pipe 10 Material 40 is provided. Thus, the sound absorbing material 40 is arranged in combination. It is reasonable to place them.

[0043] Both the prior art and the embodiment have been described as the ultrasonic flowmeter in which the ultrasonic transmitting means and the ultrasonic echo receiving means are integrally formed. However, even in an ultrasonic flowmeter having an ultrasonic transmitting means and an ultrasonic echo receiving means as separate bodies, the ultrasonic flowmeter can be fixed to the outer wall of the pipe at the position where the ultrasonic pulse arrives in the fluid pipe of the fluid to be measured. By providing the above-described sound absorbing material, it is possible to suppress the occurrence of measurement error due to the reflected wave due to the fluid piping force.

[0044] If the occurrence of measurement errors due to reflected waves from the pipe 10 cannot be suppressed despite the use of the sound absorbing material 40, it is considered that the position of the sound absorbing material 40 is not appropriate. In this case, the angle of incidence of the ultrasonic wave by the transducer 20 is changed. That is, by changing the type of the wedge 30, the fixed angle of the transducer 20 is changed, and the incident angle of the ultrasonic wave by the transducer 20 is changed. This is the same in any of the embodiments shown in FIGS.

Industrial applicability

[0045] The present invention is not limited to the Doppler type ultrasonic flow meter, but can also be applied to a flow meter belonging to a general ultrasonic flow meter.

It is also used in the ultrasonic flow meter manufacturing industry, ultrasonic flow meter mounting industry, and maintenance industry.

Brief Description of Drawings

FIG. 1 is a conceptual diagram showing a first embodiment.

FIG. 2 is a conceptual diagram showing a second embodiment.

FIG. 3 is a conceptual diagram showing a third embodiment.

FIG. 4 is a conceptual diagram showing a fourth embodiment.

FIG. 5 is a conceptual diagram showing a problem of a conventional technique.

FIG. 6 is a conceptual diagram showing a problem of a conventional technique.

Explanation of symbols

[0047] 10 Fluid piping 11 Fluid to be measured

12 Bubbles in fluid

15 Partial piping 16 Flange Ultrasonic transmission / reception means (Transju wedge

Sound absorbing material

Claims

The scope of the claims

[1] An ultrasonic transmitting means for injecting an ultrasonic pulse of a required frequency along an ultrasonic transducer force measuring line into a fluid to be measured in a fluid pipe; Measuring area force receives the reflected ultrasonic echo and measures the flow velocity distribution of the fluid to be measured in the measuring area, and a fluid velocity distribution measuring means based on the flow velocity distribution of the fluid to be measured. An ultrasonic flowmeter for measuring the flow rate of the fluid to be measured, comprising: a flow rate calculating means for calculating the flow rate of the fluid to be measured in the measurement area; An ultrasonic flowmeter comprising a high-density sound-absorbing material having an acoustic impedance that approximates the acoustic impedance of the fluid pipe on an inner wall of the fluid pipe near the fixing pipe.

[2] An ultrasonic flowmeter fixed by being sandwiched between fluid pipes related to a fluid to be measured,

A partial pipe having the same inner diameter as the fluid pipe,

A flange for fixing the partial pipe to the fluid pipe related to the fluid to be measured; and an ultrasonic pulse fixed to the partial pipe and having a required frequency in the fluid pipe along the measurement line from the ultrasonic transducer. Means for transmitting ultrasonic waves into the fluid,

The inner wall of the partial pipe to which the ultrasonic wave incident by the ultrasonic transmission means reaches is provided with a high-density material sound-absorbing material having an acoustic impedance that approximates the acoustic impedance of the fluid pipe,

The ultrasonic transmission means includes a fluid velocity distribution measuring means for receiving an ultrasonic echo reflected in a measurement region of the ultrasonic pulse incident on the measurement target fluid and measuring a flow velocity distribution of the measurement target fluid in the measurement region. And a flow rate calculating means for calculating the flow rate of the fluid to be measured in the measurement area based on the flow velocity distribution of the fluid to be measured.

3. The ultrasonic flowmeter according to claim 1, wherein the sound absorbing material is installed integrally with a liner provided inside the pipe.

[4] The ultrasonic flowmeter according to any one of claims 1 to 3, wherein the sound absorbing material is formed of a material formed by mixing high density metal powder with a synthetic resin.