JPH03110491A - Detection of underwater suspended matter - Google Patents

Abstract

PURPOSE:To easily and surely detect presence of underwater suspended matter by comparing the wave form of ultrasonic wave received with an ultrasonic wave receiver with the wave form of ultrasonic wave oscillated from an ultrasonic wave oscillator and detecting the suspended matter from difference of both wave forms. CONSTITUTION:Firstly intensive ultrasonic wave 5 is oscillated toward an ultra sonic wave receiver from an ultrasonic wave oscillator 3. Then the wave form of ultrasonic wave received by the ultrasonic wave receiver 4 is compared with the wave form of ultrasonic wave oscillated from the oscillator 3 or the wave form of ultrasonic wave received when underwater suspended matter does not exist. Existence of medusas 6 is detected from the difference of both wave forms. In other words, the ultrasonic wave oscillated from the oscillator 3 is pressure propagation wave. Sound is changed into a nonlinear form between one period of ultrasonic wave by the nonlinear acoustic propagation characteristics for the pressure of an organism in the place wherein medusas float. When medusas 6 exist midway, the wave form of received ultrasonic wave is changed as shown in a curve (b). When the curves (a), (b) are compared, both curves differ as shown in the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting floating objects in water. This signal is used as a signal to detect floating objects when detecting the presence of floating objects and taking measures to prevent them from entering the water intake.

[Conventional technology]

Traditionally, seawater has been used as cooling water when condensing steam for power generation, but sometimes jellyfish occur in the seawater, and the jellyfish are sucked into the cooling water intake along with the seawater and filtered. This may cause the power plant to become unable to operate due to a decrease in the amount of water absorbed for cooling.

In order to prevent this, for example, as a first means, Japanese Patent Publication No. 82-6044, as a second means, Japanese Patent Application Laid-Open No. 61-254712, and as a third means, Japanese Patent Application Laid-open No. 1982-139146. As a fourth means, a method described in Japanese Utility Model Application Laid-open No. 61-134274 is known.

However, in the first method described above, the flow rate of the heated wastewater is increased and it is discharged from the water outlet below the sea surface, and cooling water is flowed in at a small flow rate from the water intake below that, which causes a large amount of jellyfish to be generated. In such a case, although the flow rate is small, it cannot be expected to prevent the jellyfish from being sucked into the water intake.
A net is installed to prevent the inflow of jellyfish.If a large number of jellyfish occur, they will inevitably attach to the net and reduce the amount of water intake. This method attempts to collect jellyfish near the water intake, and it is extremely difficult to prevent large numbers of jellyfish from being sucked into the water intake.

Therefore, the present inventors developed an underwater system that prevents jellyfish and garbage from being sucked into the cooling water intake even if a large number of jellyfish occur or a large amount of garbage is floating in the sea. Proposed a device for removing floating objects, and filed a patent application in 1983
No. 43440, Utility Application No. 1-43011, Patent Application No. 1-1
24197, Jitsugan Hei 1-124198, Jitsugan Hei 1-
No. 57089, Jitsugan No. 1-58165, Jitsugan No. 1-5
The application has been filed as No. 8166.

In the above application, an upflow generator is installed on the seabed in front of the cooling water intake, and the upflow generator generates an upflow, and the floating objects such as jellyfish and garbage in the sea are removed by the upflow. The object is placed on the water and floated near the water surface, and the objects floating in the water are removed from the water intake port.

[Problem to be solved by the invention]

However, the above-mentioned application uses an upflow generating device,
Since the operation is performed in anticipation of the arrival of floating objects in the water, there is a problem in that, as a result, operation when the floating objects in the water do not arrive becomes a wasteful operation and is not economical.

The present invention relates to a method for detecting floating objects in water that can solve the problems listed in item L.

That is, an object of the present invention is to provide a method for detecting floating objects in water that can reliably detect the presence or absence of floating objects in water and prevent wasteful operation of a device for removing floating objects in water. It is something.

[Means to solve the problem]

In order to achieve the above object, the underwater floating object detection method of the present invention includes installing an ultrasonic oscillator in the water on one side near the point where the underwater floating object to be detected passes; An ultrasonic receiving device is installed in the water on the other side near the spot, facing the ultrasonic oscillating device, and ultrasonic waves are oscillated from the ultrasonic oscillating device toward the ultrasonic receiving device, and the ultrasonic waves are Compare the waveform of the ultrasonic wave emitted from the oscillator or the waveform of the ultrasonic wave received when there is no floating object in the water with the waveform of the ultrasonic wave received by the ultrasonic receiver, and determine the difference between the two waveforms. The presence or absence of floating objects in the water can now be detected.

[Effect]

Ultrasonic waves emitted from an ultrasonic oscillator are pressure propagation waves. In general, the acoustic properties of living organisms such as fish and jellyfish change depending on pressure, so when a strong ultrasound is applied to them, the speed of sound changes at the peaks (high pressure) and troughs (low pressure) of the ultrasound, so the incident wave and transmitted waves, the waveform changes. for example,
When a sine wave is input, the transmitted wave becomes a distorted wave. That is,
In areas where underwater objects such as jellyfish are floating, the sound speed of ultrasonic waves changes nonlinearly during one cycle. therefore,
When a floating object exists between an ultrasonic oscillator and an ultrasonic receiver installed underwater, the waveform of the ultrasonic waves received by the ultrasonic receiver will differ from the waveform oscillated by the ultrasonic oscillator. Since the waveform is different from that of the ultrasonic wave, the presence or absence of floating objects in the water can be detected from the difference between the two waveforms or by comparing the waveform when no floating objects are present with the received waveform. For example, if the waveform of the ultrasonic wave received by the ultrasonic receiving device is subjected to Fourier analysis, it is possible to easily determine the difference between the two waveforms.

〔Example〕

FIG. 1 shows an example of a device for carrying out the detection method of the present invention. In the figure, 1 is a water surface, 2 is a seabed, 3 is an ultrasonic oscillator, 4 is an ultrasonic receiver, and 5 is an ultrasonic wave receiver. Sound waves and 6 are jellyfish.

To explain further, an ultrasonic oscillator 3 and an ultrasonic receiver 4 are installed underwater at a certain height from the seabed 2 in front of a cooling water intake of a power plant (not shown). That is, the ultrasonic oscillator 3 is installed in the water on one side near the point where the jellyfish 6, which is the floating object in the water, passes through, and the ultrasonic oscillator 3 is placed in the water on the other side facing the ultrasonic oscillator 3 to receive the ultrasonic waves. Device 4 is installed.

First, from the ultrasonic oscillator 3 to the ultrasonic receiver 4
A powerful ultrasonic wave 5 is oscillated towards The waveforms of the ultrasonic waves are compared, and the presence or absence of the jellyfish 6 is detected from the difference between the two waveforms.

That is, the ultrasonic waves oscillated from the ultrasonic oscillator 3 are
This is a pressure propagation wave, and where the jellyfish 6 is floating, the sound speed changes nonlinearly during one cycle of the ultrasonic wave due to nonlinear acoustic propagation characteristics with respect to the pressure of the living body.

For example, the waveform of the ultrasonic waves emitted from the ultrasonic oscillator 3 is as shown by curve a in FIG. The waveforms of are already shown in the curves in Figure 3, and these curves a.

Comparing b, there are differences as seen in FIG.

Therefore, the presence or absence of the jellyfish 6 can be detected from the difference between the two waveforms a and b. For example, if the waveform of curve a in Figure 4 is subjected to Fourier analysis, it will become a figure C with diagonal lines in the fifth factor line, and if the waveform of curve Mb in Figure 4 is subjected to Fourier analysis, it will become figure C with parallel diagonal lines in Figure 6. As shown in figures c, d, and e, harmonics are generated, and the difference in waveforms when the jellyfish 6 is present becomes easily clear.

In this way, when the arrival of the jellyfish 6 is detected, this detection signal is input to the jellyfish removal device (not shown), which starts immediately and the jellyfish 6 enters the cooling water intake. Make sure you have nothing to do.

In addition, in the example illustrated above, the jellyfish 6 was explained, but
For example, detection of underwater objects such as fish can be performed in a similar manner.

〔Effect of the invention〕

As explained above, according to the present invention, floating objects in water can be detected using ultrasonic waves based on the waveform of the ultrasonic waves emitted from the ultrasonic oscillator and the waveform of the ultrasonic waves received by the ultrasonic receiver. Although this method detects from the difference between the two waveforms, it has the effect of being able to detect the presence or absence of floating objects in the water very easily and reliably.

[Brief explanation of drawings]

FIG. 1 is a partially cross-sectional front view showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is an explanatory diagram showing an example of the waveform of an ultrasonic wave emitted from the ultrasonic oscillator shown in FIG. 1. , FIG. 3 is an explanatory diagram showing an example of the waveform of the ultrasonic wave received by the ultrasonic receiving device, FIG. 4 is an explanatory diagram comparing the waveform of FIG. 2 with the waveform of FIG. 3, and FIG. FIG. 6 is an explanatory diagram showing the results of Fourier analysis of waveform a in FIG. 4, and FIG. 6 is an explanatory diagram showing the results of Fourier analysis of waveform a in FIG. 1... Water surface, 2... Seabed, 3... Ultrasonic oscillator, 4 - Ultrasonic receiver, - Ultrasonic wave, jellyfish. The first district inspector

Claims (1)

[Scope of Claims] 1. An ultrasonic oscillator is installed in the water on one side near the point where the underwater floating object to be detected passes, and the ultrasonic oscillator is installed in the water on the other side near the point where the underwater floating object passes. An ultrasonic receiver is installed opposite to the ultrasonic oscillator, and the ultrasonic oscillator oscillates an ultrasonic wave toward the ultrasonic receiver, and the waveform of the ultrasonic wave emitted from the ultrasonic oscillator or A feature is that the waveform of the ultrasonic waves received when there is no floating object in the water is compared with the waveform of the ultrasonic wave received by the ultrasonic receiving device, and the presence or absence of the floating object in the water is detected from the difference between these two waveforms. A method for detecting floating objects in water. 2. Compare the waveform of the ultrasonic wave received by the ultrasonic receiving device with the waveform of the ultrasonic wave emitted from the ultrasonic oscillator or the analysis result of the ultrasonic wave shape received when there are no floating objects in the water by Fourier analysis etc. 2. The method for detecting floating objects in water according to claim 1, which comprises determining the difference. 3. Claim 1, wherein an ultrasonic oscillator and an ultrasonic receiver are installed in front of a cooling water intake into which seawater is introduced as cooling water to detect floating objects in the water that are about to enter the cooling water intake. Or the method for detecting floating objects in water according to 2. 4. The method for detecting floating objects in water according to claim 3, wherein the floating objects in water are a group of jellyfish.