JPH06230024A - Ultrasonic inspection method - Google Patents

Abstract

PURPOSE:To make it possible to observe the flow of solvent-particulates suspen sion which can not be visually obserbed by using as a tracer a particulate of which the specific gravity is same as the suspension and the particle size is similar to that of the suspended particulate. CONSTITUTION:Magnetite Fe2O43 is spread on a hollow glass bead 2 so as to control the specific gravity. Control of the specific gravity is adjusted by the thickness of the magnetite layer. By adjusting the specific gravity of a tracer same as that of water, the tracer is moved along the flow of water. The sensitivity of detection level of a reflecting signal is lowered, speckle signal reflecting from particulates are reduced, and hence the sensitivity is adjusted so as to detect a strong reflecting signal generated due to resonance from the tracer. In this way, even in the condition of generating speckles, the flow can be inspected by pursuing the tracer. Namely, the flow of solvent-particulates suspension which can not be observed hitherto can be observed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for clarifying the flow behavior of a solvent / fine particle suspension by ultrasonic measurement.

[0002]

2. Description of the Related Art Conventionally, ultrasonic inspection methods have been used in various fields because they have the advantage of being nondestructive and simple. If the field of use is illustrated, (1) Metal flaw detection measurement used for nondestructive inspection of a metal solid by utilizing the echo of an ultrasonic pulse in the solid. (2) A medical diagnosis in which a tumor or the like in the body is detected by a change in the reverberation of an abnormal portion of cellular tissue in the living body. (3) Metal thickness measurement that measures the thickness of a high-pressure tank, boiler, etc. from the outside by utilizing the interference with the transmitted wave for reflection from a reflecting surface such as metal. (4) Wind velocity and blood flow measurement to measure the flow of fluid using the Doppler effect. Etc.

In order to clarify the flow behavior of the solvent / ultrafine particle suspension, which is the field of application of the present invention, a method utilizing the above-mentioned Doppler effect has been studied so far, but still satisfactory results are obtained. It was not obtained.

In addition to the ultrasonic measurement method, as a method of clarifying the behavior of the flow of the solvent / fine particle suspension, dye, plastic fine particles, glass beads or metal fragments are injected into the suspension as a tracer and the state is visually observed. Observing has been mainly done. Since these tracers are not adjusted to the same as the specific gravity of the suspension, they separate from the flow over time and only follow the flow on the surface, not the flow inside the suspension. There was a problem that I could not measure.

Recently, in fluid engineering, it is required to clarify the behavior of suspensions such as water / carbon suspension (black) and water / silica suspension (white) that cannot be inspected by visual inspection because light does not pass therethrough. Is becoming popular.

Further, it has been desired in the field of plant industry to clarify the behavior of the suspension flowing in the closed pipe. However, since the conventional inspection method cannot perform visual observation, the behavior of the flow remains unclear.

[0007]

Conventionally, in order to visualize a flow that cannot be visually observed, ultrasonic observation has been attempted.

In ultrasonic measurement, when the flow of suspension is fast, the Doppler method utilizing the difference in speed of fine particles in suspension is used, but complete contrast is not obtained. On the other hand, if the flow is slow, there is a problem that the Doppler method cannot measure.

As a method for visualizing a slow-flowing suspension, it is possible to use the B-mode method.
In a suspension in which fine particles with small ultrasonic reflection echoes (small specific impedance) are dispersed in a colloidal form, echoes are not measured and images showing flow behavior are not observed.

On the other hand, in the case of suspension in which a few percent of fine particles having high specific impedance are suspended, speckle due to reflected echo is observed. This speckle is observed throughout the flow, and its relationship with the behavior of the flow is not simple. At present, it is not possible to accurately grasp the behavior of the flow only by measuring this speckle.

An object of the present invention is to visualize the flow of a solvent / fine particle suspension in which the particles in the suspension generate speckles and the flow cannot be visually observed.

[0012]

In order to achieve the above-mentioned object, in the inspection method of the present invention, a material and a material having a large specific impedance and an ultrasonic resonance phenomenon occur.
The shape is controlled, and fine particles having a particle size similar to that of the fine particles suspended with the same specific gravity as the suspension are used as a tracer for ultrasonic inspection.

[0013]

EXAMPLES The basic characteristics of a tracer will be described as a pre-stage for explaining an example of the inspection method of the present invention. A schematic sectional view of the shape of the tracer used in the present invention is shown in FIG. Magnetite (Fe ₂ O ₄ ) 3 is coated on the hollow glass beads 2 in order to control the specific gravity. The control of specific gravity can be adjusted by the thickness of the magnetite layer.

FIG. 2 shows the relationship between the particle size of the tracer and the resonance frequency. Therefore, the resonance frequency can be controlled by changing the particle size.

FIG. 3 shows the result of comparing the intensities of the reflection spectrum of the tracer which resonates with the reflection spectrum of the fine particles in the suspension. Since the tracer resonates, a sensitivity of 20 db or more is obtained as compared with the spectral intensity of the fine particles in the suspension.

When the particles in the suspension generate speckles and the flow cannot be measured: An example of visualizing the flow using the tracer will be described below.

FIG. 4 shows a B-mode image obtained by ultrasonic measurement of a suspension in which highly reflective microspheres having a particle size of 6 μm are suspended in degassed water. Measurement frequency is 3.5MH
z. Speckle is observed throughout the figure. Since speckles randomly occur and disappear, and reflection echoes are observed from all areas of the suspension, it is not possible to clarify the state of the flow from the observation of speckles.

FIG. 5 is a B-mode image obtained by injecting the tracer used in the present invention and performing ultrasonic observation. Reflected echoes showing the shape of an approximately inverted triangle are observed corresponding to the individual tracers. This means that the reflected echo from the tracer resonates and the reflected echo greatly increases. Since the tracer is adjusted to have the same specific gravity as water, the tracer moves along the flow of water. The flow of water was clarified by tracing the state of this tracer.

FIG. 6 is a B-mode image in which the tracer used in the present invention is injected into the suspension shown in FIG. In the detection of ultrasonic waves, the sensitivity of the detection level of the reflected signal was lowered, the speckle signal reflected from the particles was reduced, and the sensitivity was adjusted so that the strong reflected signal generated by resonance from the tracer could be detected. Even when speckles are generated, the flow can be inspected by tracing the tracer as in the case of FIG.

The reason why the hollow fine particles with a magnetic layer are used in this embodiment is that the fine particles can be controlled by an external magnetic field to collect the fine particles at the observation site and to collect them after the observation.

[0021]

As described above, the ultrasonic inspection method using the tracer in which the resonance phenomenon of the ultrasonic wave and the specific gravity are adjusted enables the visualization of the flow of the solvent / particulate suspension which could not be observed conventionally. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a tracer.

FIG. 2 is a diagram showing a relationship between a particle diameter and a resonance frequency of a tracer used in the present invention.

FIG. 3 is a diagram showing a relationship between power spectra of fine particles and a tracer.

FIG. 4 is a diagram showing a B-mode image of water / fine particle suspension.

FIG. 5 is a diagram showing a B-mode image of water / tracer.

FIG. 6 is a view showing a B-mode image of a water / fine particle suspension in which a tracer is injected.

[Explanation of symbols]

1 gas 2 glass 3 surface layer (Fe ₂ O ₄ )

Claims (2)

[Claims] 1. An ultrasonic inspection method for measuring a behavior of a flow of a solvent / fine particle suspension by ultrasonic waves, characterized by using a tracer that resonates with a measurement frequency and follows the flow of the suspension. 2. A tracer in which a shape of fine hollow particles containing gas is controlled so as to resonate at a measurement frequency and a material for controlling the specific gravity is added to the surface layer of the hollow fine particles is used. The ultrasonic inspection method according to claim 1.