JPH10197317A - Apparatus for detecting liquid level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a liquid level in a glass melting furnace or the like with good accuracy and to enhance durability and reliability by a method wherein a level detecting rod is raised vertically by using an air cylinder mechanism so as to be then dropped into the level. SOLUTION: An air cylinder mechanism 6 is driven, and a level detecting rod 5 is raised vertically so as to be positioned in the uppermost part of a cylinder body 9. Then, the reference position of the level detecting rod 5 is detected by a position detector 20, an open valve 17' is opened, the inside of a working-fluid line 14 is opened to the air, and the level detecting rod 5 is dropped spontaneously. Then, as soon as a resistor 11 at the lower end part of the level detecting rod 5 collides with a level L, an acceleration is changed (reduced) all at once due to its resistance. As a result, when a graduation 10 at the level detecting rod 5 in that moment is detected by the position detector 20, it is possible to measure a distance H up to the level L from a ceiling wall 1a inside a furnace. Then, on the basis of the distance H, the liquid level of a molten glass inside the furnace can be found instantaneously by a measuring part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a liquid level in a glass melting furnace or the like used for vitrifying high-level radioactive liquid waste.

[0002]

2. Description of the Related Art Generally, high-level radioactive liquid waste generated in a reprocessing step of spent nuclear fuel used in a nuclear power plant is difficult to handle as a liquid, and as shown in FIG. It is put into a glass melting furnace, where it is melted at a high temperature (1100 ° C. to 1200 ° C.) to form a molten glass, and then placed in a closed stainless steel container called a canister connected to the lower part of the glass melting furnace. It is hardened to a stable form as a vitrified body. After that, this vitrified body is naturally cooled,
After going through the decontamination process, inspection process, etc., it is being disposed of geologically in rocks several thousand meters underground.

[0003]

However, in order to stably produce this vitrified body, it is necessary to always accurately detect the liquid level in the glass melting furnace. Examples of the method include measuring a supply amount of a glass raw material and a high-level radioactive liquid waste and the weight of a canister to calculate a liquid level by calculation, and a method in which a plurality of electrode-type level switches and a float-type liquid level meter are provided in a glass melting furnace. A method using is considered. However, the calculation detection method tends to cause errors,
In the method using the electrode type level switch or the float, it is difficult to accurately detect the liquid level, and since the liquid level is constantly exposed to high temperatures, the durability and the reliability are greatly deteriorated. There was a drawback.

Accordingly, the present invention has been devised in order to effectively solve such a problem, and its object is to accurately detect a liquid level in a glass melting furnace or the like and to improve durability and reliability. It is intended to provide a novel liquid level detecting device capable of improving the liquid level.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to vertically penetrating a ceiling wall of a container such as a glass melting furnace so as to be vertically movable, and a lower end portion of the liquid such as a molten glass in the container. A level detection rod extending to the surface side, an air cylinder mechanism for vertically raising the level detection rod and dropping it on the liquid surface, and a level detection rod for the container based on a change in acceleration when the level detection rod falls. And position detecting means for detecting a position.

That is, if the level detecting rod is vertically raised by the air cylinder mechanism and then dropped, the falling acceleration changes at the moment when the level detecting rod collides with the liquid surface. The liquid level in the container can be determined by detecting the position of the level detection rod at the moment when the value changes.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a liquid level detecting device for a glass melting furnace according to the present invention. In the drawing, reference numeral 1 denotes a glass melting furnace, which is one of containers for storing liquid, and 2
Is an electrode for melting the raw material in the glass melting furnace 1 to form molten glass, 3 is a raw material supply pipe for supplying high-level radioactive waste liquid together with the glass raw material into the furnace, and 4 is an off-gas pipe for exhausting gas in the furnace. is there.

As shown in the figure, the liquid level detecting device is provided above a ceiling wall 1a of a glass melting furnace 1, and a rod-shaped level detection rod 5 vertically penetrating the ceiling wall 1a; It mainly comprises an air cylinder mechanism 6 for moving the detection rod 5 up and down, and position detection means 7 for detecting the position of the level detection rod 5 with respect to the glass melting furnace 1.

First, the level detecting rod 5 has a lower end vertically extending through a through hole 1b formed in the ceiling wall 1a and extending inside the furnace, and an upper end thereof constitutes an air cylinder mechanism 6. The cylinder body 9 is vertically movable vertically through the top of the cylindrical cylinder body 9.
A disk-shaped partition plate 8 extending in the horizontal direction is fixed to a substantially central portion of the level detection rod 5 so as to partition the inside of the cylinder body 9 of the air cylinder mechanism 6 up and down. Has become. Furthermore, this level detection rod 5
Is provided with a scale 10 along its length direction, and a coin-shaped resistor 11 is provided at its lower end.

Next, as described above, the air cylinder mechanism 6 is connected to the cylinder body 9, working fluid ports 12 and 13 formed above and below the cylinder body 9, and connected to the working fluid ports 12 and 13, respectively. It mainly comprises a loop-shaped working fluid line 14 through which a working fluid flows, and an air cylinder driving unit 15 such as an electric pump.
By forcibly circulating the working fluid (air) in the working fluid line 14 by the air cylinder driving unit 15, the partition plate 8 in the cylinder body 9, that is, the level detection rod 5 is attached to the axis of the cylinder body 9. It can be moved vertically up and down. The working fluid line 14 is provided with an electromagnetic valve 16 for stopping the flow of the working fluid (air) in the working fluid line 14 and opening valves 17 and 17 ′ for opening the inside of the working fluid line 14. These solenoid valves 1
The control unit 18 arbitrarily controls the control unit 6, the release valves 17, 17 ′, and the above-described air cylinder driving unit 15.

Next, the position detecting means 7 includes the level detecting rod 5
An acceleration detector 19 such as a piezoelectric accelerometer integrally provided on the top of the cylinder, a position detector 20 such as an optical sensor provided near the level detection rod 5 on the top of the cylinder body 9, and an acceleration detector 19 And a liquid level measurement unit 21 for inputting the output value of the position detector 20. The acceleration detector 19 detects the acceleration when the level detection rod 5 is dropped, and detects the acceleration when the acceleration changes. The position of the level detection rod 5 is detected by the position detector 20 and the output value is calculated by the liquid level measuring unit 21 to detect the liquid level in the furnace. The liquid level measuring unit 21
Is connected to the control unit 18, and the measured value is displayed on a display unit 22 such as a CRT connected to the control unit 18. Reference numeral 23 in the figure denotes a stopper provided on the top of the cylinder body 9 for restricting the amount of the level detection rod 5 from falling.

Next, an example of a liquid level measuring method by the apparatus of the present invention having such a configuration will be described.

In order to measure the liquid level of the molten glass in the glass melting furnace 1 using the apparatus of the present invention, first, the air cylinder mechanism 6 is driven to raise the level detection rod 5 vertically, 5 The resistor 11 at the lower end is located above the liquid level of the molten glass in the furnace. Specifically, after closing the open valve 17 ′ of the air cylinder mechanism 6 and opening the on-off valve 17, the air cylinder driving unit 15 is driven to send air below the partition plate 8 in the cylinder body 9, The level detection rod 5 is raised vertically by extracting the working fluid (air) above the plate 8 from the on-off valve 17, and then the flow of the working fluid (air) in the working fluid line 14 is stopped by the solenoid valve 16. The level detection rod 5 that has been raised can be stopped at that position.

Next, when the level detecting rod 5 is raised to the uppermost part of the cylinder body 9 as described above, the position detecting means 7 is activated, and the position detector 20 determines the reference position of the level detecting rod 5. After the detection, the release valve 17 'on the working fluid line 14 is opened to open the inside of the working fluid line 14 to the atmosphere, and the level detection rod 5 is naturally dropped vertically. Then, the moment the lower end resistor 11 of the level detection rod 5 collides with the liquid surface, the acceleration changes (decreases) at once by the resistance.
Therefore, the distance (H) from the furnace ceiling wall 1a to the liquid level (L) can be measured by detecting the scale 10 of the level detection rod 5 at that moment by the position detector 20 in the same manner.

Since the size and capacity in the furnace are known in advance at the design stage, the molten glass in the furnace is determined based on the distance (H) from the furnace ceiling wall 1a to the liquid level (L). The liquid level is obtained instantaneously by the liquid level measuring unit 21. Thereafter, such measurement is performed at regular intervals (for example, 2
(Interval of 3 minutes), the glass melting furnace 1
The liquid level of the molten glass inside can always be detected with high accuracy.

As described above, according to the present invention, the liquid level is detected by dropping the rod-shaped level detection rod vertically from the liquid surface of the molten glass and detecting a change in the acceleration thereof. The liquid level in the glass melting furnace 1 can be easily and accurately detected. In addition, since most of the present apparatus is located outside the glass melting furnace 1, the influence of heat in the melting furnace 1 is small, and high reliability can be exhibited. In this embodiment, an example of a glass melting furnace for high-level radioactive liquid waste has been described. However, the present invention is not limited to this, and a container whose liquid level cannot be easily determined from the outside. For example, it goes without saying that the present invention can be similarly applied to a chemical tank, an LNG storage tank, a blast furnace, and the like.

[0018]

In summary, according to the present invention, the liquid level of a molten glass in a glass melting furnace or the like whose liquid level cannot be easily determined from the outside can be accurately detected, and most of the apparatus can be used. Since it is not affected by heat, corrosion, and the like, it exhibits excellent effects such as greatly improved durability and reliability.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a conventional glass melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container (glass melting furnace) 5 Level detection rod 6 Air cylinder mechanism 7 Position detection means L Liquid level

Claims (2)

[Claims] 1. An apparatus for detecting a liquid level in a container for storing liquid, comprising: a level detection rod which vertically penetrates vertically through a ceiling wall of the container and has a lower end extending toward a liquid surface side in the container; An air cylinder mechanism for vertically raising the level detection rod and dropping the liquid on the liquid surface, and position detection means for detecting the position of the level detection rod with respect to the container from a change in acceleration when the level detection rod is dropped. A liquid level detecting device, characterized in that: 2. The container according to claim 1, wherein the container is a glass melting furnace for melting a high-level radioactive liquid waste together with a glass raw material at a high temperature, and the liquid is molten glass at 1000 ° C. to 1200 ° C. Liquid level detector.