JPS62816A - Ultrasonic level measuring device - Google Patents

Abstract

PURPOSE:To obtain an instrument which is not affected by rocking of bubbles produced on the surface of liquid and of inflow liquid by providing a protection pipe which surrounds the radiation and reflection areas of an ultrasonic wave from an ultrasonic wave transmitter in a liquid collection tank, and injecting washing into the projection pipe when necessary. CONSTITUTION:When waste liquid is injected from an intake nozzle 5 and liquid for stirring is discharged from a stirring nozzle 6 to perform stirring, numbers of bubbles 17 are formed on the surface 8 of the liquid. However, the liquid level 8' in the reflection area of the ultrasonic wave 10 emitted by the ultrasonic wave transmitter 9 is partitioned by the protection pipe 12 at any time, so even if bubblesd 17 are formed in a tank 1, they never enters the liquid surface 8'. Therefore, the ultrasonic wave 10 from the transmitter 9 is emitted to the liquid surface 8' where there is no bubble and reflected there, so the level of the liquid surface 8' is measured accurately. This liquid surface 8' is at the same level as the liquid surface 8 in the tank 1 because the protection pipe 12 communicates with the inside of the tank 1 through a vent hole 13. Then, when bubbles 17' are formed on the liquid surface 8', a valve 15 is opened to inject the washing from a sprayring 14, eliminating the bubbles 17'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ultrasonic level measuring device used for detecting the level of waste treatment system tanks of a nuclear power plant, for example.

[Technical background of the invention and its problems]

Radioactive liquid waste from nuclear power plants, such as equipment drain water and building floor drain water, is collected in a waste liquid collection tank and then sent to the waste liquid treatment system for filtration and desalination. The level of waste liquid in the waste liquid collection tank is controlled by an ultrasonic level meter for measurement.

This measuring ultrasonic level meter measures the liquid level by emitting ultrasonic waves to the rising liquid level from an ultrasonic transmitter attached to the top of the tank, and reducing the round trip time of the ultrasonic waves to 1/2. . However, in level measurement using this ultrasonic level meter, the most important constraint that must be taken into consideration is the bubbles generated on the liquid surface.

The main causes of bubbles are the effect of waste liquid entering the tank from the inflow nozzle and the effect of stirring in the tank by the stirring nozzle. This is because when bubbles are generated on the liquid surface in the tank, the ultrasonic waves emitted from the ultrasonic transmitter are reflected and scattered by the bubbles. Waste collected in collection tanks in the waste treatment system of nuclear power plants is
Due to their nature, there are many things that may cause irritation.
For level measurement in such waste liquid collection tanks.

It was considered difficult to use an ultrasonic level meter.

In addition, when measuring levels using ultrasonic waves, there are other points that must be taken into consideration other than bubbles. When waste liquid flows into the tank from the inflow nozzle, it is important to prevent the inflow liquid from entering the path of the ultrasonic waves. be.

If this point is not taken into account, it will not be possible to accurately measure the liquid level, as in the case of bubbles.

[Purpose of the invention]

An object of the present invention is to provide an ultrasonic level measuring device that is not affected by bubbles generated on the liquid surface or agitation of the inflowing liquid.

[Summary of the invention]

The ultrasonic level measuring device according to the present invention includes a liquid collection tank provided with an ultrasonic transmitter for level measurement, a protection tube suspended in the liquid surrounding the ultrasonic propagation area within the collection tank, and a protection tube inside the protection tube. The protective tube is characterized by comprising a spray ring that sprays cleaning water onto the liquid surface inside the tube as necessary, and a communication hole provided in the protective tube that communicates between the inside and the outside.

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings. In the drawing, for example, a waste liquid collection tank 1 of a waste treatment system of a nuclear power plant is mounted on a power plant foundation 2 by a mount 3. The upper opening of this collection tank 1 is closed by an upper M4, and the waste liquid is injected from the upper inflow nozzle 5. The waste liquid accumulated in the collection tank 1 is agitated by jetting fluid from the agitation nozzle 6. The waste liquid that has been processed such as stirring in the collection tank 1 is sent from the liquid outlet nozzle 7 to the next processing step.

The liquid level 8 in the collection tank 1 is measured using the emission of ultrasonic waves 10 from an ultrasonic transmitter 9.

In the tank 1, bubbles 11 are generated on the liquid surface 4 when the liquid flows in from the inflow nozzle 5 or when the liquid is stirred by a jet from the stirring nozzle 6. This bubble 11 disturbs the reflection point of the ultrasonic wave 10 emitted from the ultrasonic transmitter 9, making it impossible to accurately measure the level of the liquid surface 4.

Therefore, the present invention is characterized in that a protection tube 12 is provided in the collection tank 1, which extends to the vicinity of the bottom 11 of the tank 1 along the emission direction of the ultrasonic waves 10 emitted from the ultrasonic transmitter 9. In the specific configuration shown in the drawing, the protective tube 12 is suspended into the tank 1 from the upper lid 4 to which the ultrasonic transmitter 9 is attached, and the tube is a large tube that does not interfere with the emission and reflection of the ultrasonic wave 10. Satoru.

A vent hole 13 is provided in the upper part of the protection tube 12 that communicates the inside and outside, and the liquid level 8' in the protection tube 12 and the liquid level 8 in the tank 1 are connected.
This is to prevent the edges from shifting. Further, a spray ring 14 is provided to eliminate bubbles when bubbles are formed on the liquid surface 8' in the protection tube 12, and cleaning water is sprayed from the spray hole 16 by opening a valve 15. It is.

Next, the operation of the ultrasonic level measuring device according to the present invention configured as described above will be explained. In the drawing.

When the waste liquid is injected from the inflow nozzle 5 and when the stirring liquid flows out from the stirring nozzle 6 and is stirred, a large number of bubbles 17 are generated on the liquid surface 8 of the tank 1. However, in the present invention,
Since the liquid surface 8' in the reflection area of the ultrasonic wave 10 emitted from the ultrasonic transmitter 9 is always partitioned off by the protection tube 12, even if bubbles 17 occur in the tank 1, the liquid surface 8' of the protection tube 12
′ will not be invaded. Therefore, the ultrasonic wave 10 from the ultrasonic transmitter 9 is emitted to the true liquid surface 8' without bubbles and is reflected at 2\, making it possible to accurately measure the level of the liquid surface 8'. . The liquid level 8' of the protective tube 12 is the same level as the liquid level 8 in the tank 1 because the protective tube 12 communicates with the inside of the tongue 1 through the vent hole 13.

Also, when injecting waste liquid into the collection tank 1 or stirring it,
Although the liquid level 8 may fluctuate greatly, by extending the protective tube 12 to the vicinity of the bottom 11 of the tank 1, this fluctuation in the liquid level can be prevented from affecting the liquid level 8' of the protective tube 12. It is also possible to prevent the bubbles 17 from entering the protective tube 12 due to this fluctuation of the liquid level. Furthermore, in the unlikely event that bubbles 17' enter the protective tube 12 and float on the liquid surface 8'. This is because when the waste liquid is initially injected into the collection tank 1 from the inlet nozzle 5, as the liquid level rises, bubbles 17' may rise within the protective tube 12 and float on the liquid level 8'. In this way, if bubbles 17' occur on the liquid surface 8' of the protection tube 12, the bubbles 17' can be removed by opening the valve 15 and spraying cleaning water through the spray hole 16 of the spray ring 14. can be made to disappear.

In the above example, the waste liquid collection tank in the waste treatment system of a nuclear power plant was explained, but bubbles are likely to occur in tanks that store liquid other than such waste liquid, and the level can be measured using ultrasonic waves. It can be carried out on things.

〔Effect of the invention〕

As described above, according to the present invention, in a liquid collection tank to which an ultrasonic transmitter for level measurement is attached, a protective tube is provided in the tank to surround the emission 1 reflection area of the ultrasonic waves emitted from the ultrasonic transmitter. A spray ring is installed inside this protection tube to inject cleaning water onto the liquid surface inside the tube as needed, and a vent hole is provided in the protection tube to communicate between the inside and outside, which prevents bubbles from forming on the liquid surface inside the collection tank. Even if the liquid level in the tank fluctuates, the protective tube will surely prevent these bubbles from entering the ultrasonic level measurement area, and even if the liquid level in the tank fluctuates, the protective tube will prevent this vibration from spreading to the level measurement area. can,
Furthermore, if bubbles form on the liquid surface in the level measuring area, they can be extinguished by spraying from the spray ring.

[Brief explanation of the drawing]

The drawing is a schematic configuration diagram showing an embodiment of an ultrasonic level measuring device according to the present invention.

Claims (1)

[Claims] (1) A liquid collection tank equipped with an ultrasonic transmitter for level measurement, a protection tube suspended in the liquid surrounding the travel area of the ultrasonic waves emitted from the ultrasonic transmitter within the collection tank, and a protection tube for protecting the liquid. Ultrasonic level measurement characterized by comprising a spray ring that injects cleaning water to the liquid level in the pipe as necessary, and a communication hole provided in the protection pipe that communicates with the inside of the collection tank above the liquid level. Device.