JP2004317288A - Ultrasonic acoustic velocity measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic acoustic velocity measuring device capable of highly accurate measurement in a short time, even if fine bubbles are included in a sample. <P>SOLUTION: This ultrasonic acoustic velocity measuring device for determining the acoustic velocity of the ultrasonic wave propagating in the sample flowing in the prescribed direction has a constitution equipped with an interception means for intercepting direct inflow of the sample into an ultrasonic wave propagation region on the upstream side of the flow of the ultrasonic wave propagation region. The device may have a constitution equipped with a water-passing material for separating bubbles from the sample on the downstream side of the interception means, or may have a constitution equipped in the interception means with a bubble adjusting means for accelerating mutual combination of the bubbles existing in the sample. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic sound velocity measuring apparatus, and more particularly, to an apparatus for measuring a sound velocity of an ultrasonic wave propagating in a sample in which bubbles exist.
[0002]
[Prior art]
FIG. 8 is an external view showing a sensor 50 provided in the ultrasonic sound velocity measuring device. A reflection plate 2b is provided at a position at a predetermined distance from the ultrasonic transmission / reception unit 2a, and a sample is filled between the ultrasonic transmission / reception unit 2a and the reflection plate 2b. With this structure, the ultrasonic wave transmitted from the oscillation element 2d provided in the ultrasonic transmission / reception section 2a is reflected by the reflection plate 2b and is transmitted to the reception element 2d (same as the oscillation element) provided in the ultrasonic transmission / reception section 2a. It is designed to be received and converted into an electric signal.
[0003]
When an ultrasonic wave is propagated through a sample in the ultrasonic sound velocity measuring device, the sound velocity can be obtained as c = L / T from the propagation period T and the propagation distance L. Therefore, the sound velocity can be obtained by measuring the propagation period T with high accuracy. As a method of measuring the propagation period T with high accuracy, an overlap method and a sing-around method are widely known, though not described in detail here.
[0004]
Based on the sound velocity measured as described above, the physical quantity of the sample, for example, the density and the concentration can be obtained. For this reason, the ultrasonic measuring apparatus is used when measuring the concentration of a chemical used for synthesizing or cleaning a product in a chemical plant or a semiconductor factory. In this case, the sensor is installed in a pipe through which the medicine flows, and constantly measures the sound speed of the ultrasonic wave propagating through the medicine flowing between the ultrasonic transmission / reception unit 2a and the reflection plate 2b, and observes the change over time in the concentration of the medicine. I do.
[0005]
When measuring the speed of sound in the above conditions, a pump that supplies a chemical, gasification of components dissolved in the chemical due to pressure fluctuation, generation of gas due to reaction of a chemical solution, and leakage of a pipe joint, etc. Due to the above factors, a large amount of air bubbles may be included in the sample. If air bubbles are included in the sample, it is difficult to accurately measure the sound speed due to factors such as the propagating ultrasonic waves being reflected by the air bubbles and shortening the propagation distance, or being absorbed and attenuated by the air bubbles. Become.
[0006]
As a countermeasure, a method has been used in which a wire mesh is placed so as to surround the ultrasonic wave propagation region to prevent air bubbles from entering the ultrasonic wave propagation region.
[0007]
Since the above prior art is not related to the invention known in the literature, there is no prior art literature information to be described.
[0008]
[Problems to be solved by the invention]
In the above-described method of installing the wire mesh, the size of the bubble that can prevent entry into the ultrasonic wave propagation region is determined by the mesh size of the wire mesh. For example, when a wire mesh of 100 mesh (100 wires / 1 inch) using a wire having a wire diameter of 0.1 mm is used, the interval between the wires is about 0.15 mm. After passing through the wire mesh, it enters the ultrasonic wave propagation region. Therefore, in order to prevent fine bubbles from entering, it is necessary to install a wire mesh having a larger mesh number (finer mesh).
[0009]
However, when a wire mesh having a large number of meshes is used in order to prevent fine bubbles from entering, the ratio of the space of the wire mesh is reduced, so that the penetration of the sample is hindered. For this reason, it takes a long time to replace the sample existing in the ultrasonic wave propagation region with the flowing sample. For example, when the concentration of the sample changes, there is a problem that the change in the concentration cannot be detected quickly. .
[0010]
The present invention has been proposed in view of the above-mentioned conventional circumstances, and has as its object to provide an ultrasonic sound velocity measuring device capable of performing high-accuracy measurement even when fine bubbles are contained in a sample. It is assumed that.
[0011]
[Means for Solving the Problems]
The present invention employs the following means to achieve the above object. That is, the present invention provides an ultrasonic sound velocity measuring device for determining the sound velocity of an ultrasonic wave propagating in a sample flowing in a predetermined direction, wherein the sample is located in the ultrasonic wave propagation region on the upstream side of the flow in the ultrasonic wave propagation region. The structure is provided with obstruction means for preventing direct inflow.
[0012]
With this configuration, it is possible to prevent bubbles from directly entering the ultrasonic wave propagation region, and it is possible to reduce the number of bubbles entering the ultrasonic wave propagation region. As a result, the speed of sound in the sample can be accurately determined.
[0013]
Further, on the downstream side of the obstructing means, when introducing the sample, it is preferable to introduce the sample into the ultrasonic wave propagation region via a water-permeable material that separates bubbles from the sample.
[0014]
By introducing the sample through the water-permeable material, the intrusion of bubbles into the ultrasonic wave propagation region can be more reliably reduced, and more accurate measurement of the speed of sound can be performed.
[0015]
In the present invention, the obstruction means causes bubbles in the sample that collide with the obstruction means to come into contact with each other and combine to generate larger bubbles. For this reason, the water-permeable material only needs to be able to separate the bubbles having the increased size, and can have a configuration in which the sample can be easily transmitted as compared with the related art. Therefore, the replacement of the sample in the ultrasonic wave propagation region can be performed in a short time, and a change in the speed of sound due to a change in the concentration of the sample can be quickly detected.
[0016]
In addition, if the obstructing means is provided with bubble adjusting means for promoting mutual coupling of bubbles contained in the sample, for example, irregularities provided on the surface against which the sample collides, the separation of bubbles is further facilitated. .
[0017]
Note that, in the specification of the present application, the ultrasonic wave propagation region refers to a region of the ultrasonic wave transmitted from the oscillation element in which the ultrasonic wave received by the reception element propagates.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 shows a schematic functional block diagram of the ultrasonic sound velocity measuring device exemplified in each embodiment.
[0020]
When the transmitting means 10 transmits the driving signal, the ultrasonic wave is reflected multiple times between the oscillating element and the receiving element of the sensor 50 installed inside the pipe or the like, and is received by the receiving element as a received signal. The received signal is input to the receiving means 20, where it is subjected to processing such as amplification, and then input to the receiving processing means 30. Here, a continuous wave corresponding to a period from the transmission time to the reception time of the ultrasonic wave is formed, and the calculating means 40 measures the period of the continuous wave to determine the sound speed of the ultrasonic wave. The sensor 50 is provided with a temperature sensor. The output of the temperature sensor is input to the temperature measuring means 60, converted into temperature information, and input to the calculating means 40. Based on this temperature information, it is possible to perform temperature correction on the sound speed obtained by the calculating means 40.
[0021]
In the above description, a configuration to which the overlap method is applied is described as an example of a method of obtaining the propagation period T. However, the present invention is not limited to this, and an arbitrary method can be selected. From the viewpoint of measurement accuracy, it is preferable to use the method disclosed by the present applicant in JP-A-2001-56320.
[0022]
(First Embodiment)
A first embodiment of the present invention will be described with reference to FIG. FIG. 2 is an external view showing the sensor 50 installed in a pipe 200 (only a part is shown) through which the sample 100 flows in a predetermined direction. In FIG. 2, the sample 100 flows upward from below, and the sensor 50 is installed in the pipe 200 through a sensor installation port 201 provided in the pipe.
[0023]
Like the conventional sensor shown in FIG. 8, the sensor 50 includes a reflector 2b at a position at a predetermined distance from the ultrasonic transceiver 2a, and is filled between the ultrasonic transceiver 2a and the reflector 2b. The sound speed of the ultrasonic wave propagating through the sample 100 is determined. The ultrasonic transmission / reception unit 2a includes a temperature sensor 2c so that the temperature of the sample 100 can be measured.
[0024]
In the example of FIG. 2, the ultrasonic wave propagation region 1 of the sensor 50 has the upstream half surface surrounded by the non-water-permeable obstruction means 3 and the downstream half surface having the water-permeable material 4, and has a substantially cylindrical outer shape as a whole. Has made. In this structure, the sample 100 flowing in the pipe is introduced into the ultrasonic wave propagation region 1 via the water passage material 4. Further, the materials of the obstructing means 3 and the water-permeable material 4 can be arbitrarily selected, but in the present embodiment, the obstructing means 3 is a plate made of resin, and the water-permeable material 4 is 0.1 mm. 100 mesh net made of stainless steel wire.
[0025]
In the above state, the sample 100 flowing in the pipe first collides with the obstruction means 3. At this time, the bubbles contained in the sample 100 come into contact with each other and combine to form larger bubbles. Then, the expanded bubble flows downstream along the surface of the obstruction means 3.
[0026]
On the other hand, the flow of the sample 100 enters the ultrasonic wave propagation region 1 in the portion of the water-permeable material 4 (shown as a sample flow 7 in the figure). The flow of the sample 100 entering the ultrasonic wave propagation region 1 is weaker than the flow of the sample 100 in the pipe. In this state, the bubbles that have expanded and become easier to move due to the flow also flow downstream due to the strong flow due to the lower density compared to the sample 100 (in FIG. Shown as stream 8.). Even if some of the bubbles try to enter the ultrasonic wave propagation region 1, they cannot pass through the gaps of the net, which is the water-permeable material 4, and do not enter the ultrasonic wave propagation region 1.
[0027]
Thus, by adopting the above-described structure, the amount of bubbles entering the ultrasonic wave propagation region 1 can be reduced, and the speed of sound can be accurately measured. Further, in the present embodiment, since the size of the bubbles is increased by the action of the obstruction means 3, the mesh of the net, which is the water-permeable material 4, does not cause the expanded bubbles to enter the ultrasonic wave propagation region 1. You just need to choose the size. For this reason, it does not take time to replace the sample in the ultrasonic wave propagation region 1, and it is possible to quickly observe a change in the concentration of the sample 100 and the like.
[0028]
In the present embodiment, the upstream half surface is the obstruction means 3 and the downstream half surface is the water-permeable material 4. However, the present invention is not limited to this, and the sample 100 directly flows into the ultrasonic wave propagation region 1. If not, the ratio between the obstruction means 3 and the water-permeable material 4 may be arbitrarily designed. In order to replace the sample existing in the ultrasonic wave propagation region 1 in a short time, it is preferable that the obstructing means 3 has a minimum area.
[0029]
FIG. 3 is a diagram showing the results of measuring the sound speed of ultrasonic waves propagating in water by changing the flow rate of bubbles every 15 minutes (excluding the initial state) according to the present invention and the conventional example. Air bubbles were bubbled with a tube nozzle and aerated.
[0030]
In the sensor 50 used here, the water-permeable material 4 is formed of a 100-mesh net made of stainless steel having a wire diameter of 0.1 mm, and the obstructing means 3 corresponds to 上流 of the outer periphery, not the upstream half surface. The surface is configured to be impermeable. Further, the conventional example has a configuration in which the sensor is surrounded only by the water passing material 4.
[0031]
It can be understood that the measurement result A based on the present invention has a stable measurement without bubbles entering, while the measurement result B based on the conventional example has a significantly disturbed measured value due to the bubbles entering. From this result, it can be seen that the provision of the obstruction means 3 can prevent the entry of fine bubbles.
[0032]
In the present embodiment, the configuration is such that the ultrasonic wave propagation region 1 is surrounded by the water-permeable material 4. However, the present invention is not limited to this, and any configuration may be used as long as air bubbles can be prevented from entering the ultrasonic wave propagation region 1. For example, as shown in FIG. 4, flanges may be provided at both downstream ends of the obstruction means 3 so as to spread in a flange shape, so that the flow of the sample to the ultrasonic wave propagation region 1 is blocked.
[0033]
(Second embodiment)
In the first embodiment, the obstruction means 3 and the water-permeable material 4 are integrated, but the obstruction means 3 and the water-permeable material 4 do not need to be integrated. What is necessary is just to have the obstruction means 3. Therefore, in the second embodiment of the present invention, the obstructing means 3 and the water-permeable material 4 are arranged separately. FIG. 5 shows an external view of the second embodiment. Also in FIG. 5, it is assumed that the sample 100 flows upward from below, as in the example of FIG. 2 (the piping 200 is not shown).
[0034]
As shown in FIG. 5, in the second embodiment, the ultrasonic wave propagation region 1 of the sensor 50 is configured to be surrounded by only the water material 4. The configuration of the sensor 50 is the same as that of the conventional sensor shown in FIG. The obstructing means 3 having a substantially semicircular cross section is disposed at a position away from the sensor 50 by a predetermined distance on the upstream side.
[0035]
According to the above configuration, similarly to the first embodiment, it is possible to prevent air bubbles from entering the ultrasonic wave propagation region 1, and it is possible to accurately measure the speed of sound in a sample.
[0036]
(Third embodiment)
In each of the above embodiments, the water-passing material 4 disposed downstream of the obstruction means 3 is a means for directly preventing air bubbles from entering the ultrasonic wave propagation region 1. Therefore, if the structure for introducing the sample 100 into the ultrasonic wave propagation region 1 is configured to prevent the entry of air bubbles, it is not necessary to provide the water-permeable material 4. Therefore, in the third embodiment, the configuration is such that the water-permeable material 4 is not provided. Hereinafter, a third embodiment will be described with reference to FIG.
[0037]
In the present embodiment, the ultrasonic wave propagation region 1 of the sensor 50 is configured to be surrounded by only the obstruction means 3, and a sample for introducing the sample 100 into the ultrasonic wave propagation region 1 is provided at a position on the downstream side on the interference means 3. An inlet 5 is provided. In the example of FIG. 6, the sample introduction port 5 is a slit-shaped opening parallel to the ultrasonic wave propagation direction. The configuration of the sensor 50 is the same as the configuration of the above-described conventional sensor.
[0038]
According to the above configuration, the bubbles that have been combined and expanded by the action of the obstruction means 3 are caused to flow downstream and reach the sample introduction port 5. At the sample inlet 5, a flow occurs in which the sample in the ultrasonic wave propagation region 1 and the sample 100 flowing in the pipe are replaced, but the flow is weaker than the flow of the sample 100 flowing in the pipe. Therefore, the expanded bubbles flow downstream without entering the ultrasonic wave propagation region 1 from the sample introduction port 5.
[0039]
In the present embodiment, the sample introduction port 5 is a slit, but is not limited to this. For example, a plurality of openings may be used instead of the slit. Further, as shown in FIG. 7, a baffle plate 6 may be arranged inside the slit.
[0040]
In each of the above-described embodiments, by providing bubble adjusting means such as unevenness on the surface of the interference means 3 on which the sample collides, the mutual coupling of bubbles can be further promoted and larger bubbles can be obtained. Therefore, it is easy to prevent air bubbles from entering the ultrasonic wave propagation region 1.
[0041]
Further, in each of the above embodiments, the shape of the obstruction means 3 and the water-permeable material 4 is a shape having a small resistance to the flow of the sample 100. However, the present invention is not limited to this, and it is optional. It is possible to design. In addition, in Embodiments 1 and 2 described above, the water-permeable material 4 is formed of a wire mesh. However, for example, the water-permeable material 4 may be formed of a wire that is disposed at a smaller interval than the diameter of the bubbles, and separates the bubbles in the sample. The configuration is arbitrary as long as it can be performed.
[0042]
Furthermore, in each of the above embodiments, the configuration in which the ultrasonic transmitting and receiving unit 2a and the reflecting plate 2b are installed at a predetermined distance in the sample is illustrated, but the present invention is not limited to this. That is, a configuration in which an ultrasonic transmission unit and an ultrasonic reception unit are installed may be used.
[0043]
【The invention's effect】
As described above, in the present invention, the obstruction means for preventing the sample from directly flowing into the ultrasonic wave propagation region is provided on the upstream side of the ultrasonic wave propagation region, so that the bubbles directly enter the ultrasonic wave propagation region. Therefore, it is possible to accurately determine the sound speed in the sample.
[0044]
In addition, by introducing the sample into the ultrasonic wave propagation region via a water-permeable material that separates air bubbles from the sample on the downstream side of the obstruction means, it is possible to more reliably prevent air bubbles from entering the ultrasonic wave propagation region. The sound velocity can be reduced, and more accurate measurement of the speed of sound can be performed. In addition, the provision of the bubble adjusting means in the obstructing means makes it easier to separate the bubbles.
[0045]
Furthermore, since the water-permeable material only needs to be able to separate bubbles whose size has been increased by the action of the obstructing means or the bubble adjusting means, it is possible to adopt a configuration which does not hinder the permeation of the sample. Therefore, the replacement of the sample in the ultrasonic wave propagation region can be performed in a short time, and a change in the speed of sound due to a change in the concentration of the sample can be quickly detected.
[Brief description of the drawings]
FIG. 1 is a schematic functional block diagram showing an ultrasonic sound velocity measuring apparatus of the present invention; FIG. 2 is an external view showing a first embodiment of the present invention; FIG. 3 shows measurement results obtained by the present invention and a conventional method; FIG. 4 is a sectional view showing a modification of the first embodiment of the present invention. FIG. 5 is an external view showing a second embodiment of the present invention. FIG. 6 is a third embodiment of the present invention. FIG. 7 is a cross-sectional view showing a modification of the third embodiment of the present invention. FIG. 8 is an external view showing a sensor of a conventional ultrasonic sound velocity measuring device.
DESCRIPTION OF SYMBOLS 1 Ultrasonic wave propagation area 2a Ultrasonic transmitting / receiving part 2b Reflecting plate 2c Temperature sensor 2d Oscillating element and receiving element 3 Obstructing means 4 Water passing material 5 Sample introduction port 6 Baffle plate 7 Sample flow 8 Bubbles flow 10 Transmitting / receiving means 20 Receiving means Reference Signs List 30 reception processing means 40 calculation means 50 sensor 60 temperature measurement means 100 sample 200 piping 201 sensor installation port

Claims (3)

In an ultrasonic sound velocity measuring device for determining the sound velocity of ultrasonic waves propagating in a sample flowing in a predetermined direction,
An ultrasonic sound velocity measuring device, further comprising an obstruction means for preventing the sample from directly flowing into the ultrasonic wave propagation area, on the upstream side of the flow in the ultrasonic wave propagation area. The ultrasonic sound velocity measuring device according to claim 1, further comprising a water-permeable material that separates bubbles from a sample, on a downstream side of the flow of the obstruction unit. 3. The ultrasonic sound velocity measuring device according to claim 1, wherein said obstructing means includes a bubble adjusting means for promoting mutual coupling of bubbles contained in the sample.

Images