JP2001330697A - Instrument for measuring metal sludge in glass melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new instrument for measuring metal sludge in glass melting furnace that makes it possible to exactly grasp whether the metal sludge deposits or not and its quantity deposited. SOLUTION: A pair of electrodes 12 are inserted into the body 11 of a tubular instrument which is to be inserted into the body 2 of the glass melting furnace 1 and are insulated and supported in the body 11 of the instrument with an insulating material 13, the side face of the insertion tip of the body 11 of the instrument is opened, and the tips of the electrodes 12 are exposedly located in the opening part 14. Since the value of the resistance between the electrodes 12 varies if metal sludge exists, consequently, the existence or absen of the metal sludge and the condition of its deposition can be grasped exactly by detecting the value of the resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass melting furnace used for vitrifying high-level radioactive liquid waste, and more particularly to a measuring device for metal sludge generated in the glass melting step.

[0002]

2. Description of the Related Art High-level radioactive liquid waste generated after reprocessing of spent nuclear fuel has extremely high radiation and decay heat, and is difficult to dispose of as a liquid.
4 is fed into a glass melting furnace 1 having a structure as shown in FIG. 4, where it is melted together with a glass material such as borosilicate glass at a high temperature and packed in a corrosion-resistant stainless steel container called a canister c. It is planned that after being stabilized as a solid, it will be naturally cooled for a certain period of time and then disposed of deep underground.

As shown in the figure, this glass melting furnace 1
The inner bottom of the furnace main body 2 is narrowed in a funnel shape (square pyramid shape), and a flow-down hole 3 for flowing molten glass in the furnace 2 at its lowermost end.
And a pair of main electrodes 5 and 5 and auxiliary electrodes 6 and 6 provided therein.

After the high-level radioactive liquid waste and the glass raw material are introduced from an inlet 7 provided on the ceiling wall of the furnace main body 2, first, an electric current is applied between the main electrodes 5 and 5 so that the vicinity of the surface layer is obtained. Fully dissolve the high-level radioactive liquid waste and the glass raw material, and then apply electricity between the auxiliary electrodes 6 and 6 located therebelow to melt the high-level radioactive liquid waste and the glass raw material in the lower layer thereof, Finally, the bottom electrode 4
After flowing electricity between the main electrodes 5 and 5 to melt the entirety, the downflow nozzle 8 extending from the downflow hole 3 is heated by the surrounding electric heating coil 9 to melt and extract the solidified glass clogged therein. As a result, the molten glass in the furnace 2 is caused to flow down into the canister c located below the furnace 2 and hermetically sealed therein as a vitrified body.

The gas generated in the melting furnace 1 is exhausted from the exhaust port 7a as off-gas,
After the radioactive substance is completely collected and removed by an A filter or the like and rendered harmless, it is released into the atmosphere.

[0006]

By the way, in such a glass melting process, a platinum-based metal such as ruthenium or palladium contained in a high-level radioactive waste liquid precipitates as a metal oxide and a metal having a large specific gravity. Sludge may be generated, which accumulates on the bottom electrode 4 and grows along the inclined surface 2a, eventually reaches the auxiliary electrode 6 or the main electrode 5 and short-circuits with each other, causing a locally large area. There is a problem that current flows and damages the electrodes 4, 5, and 6.

For this reason, it is necessary to accurately and quickly determine whether or not metal sludge is deposited in the furnace main body 2 and the amount of the deposited metal sludge. At present, no method has been proposed to accurately determine the presence or absence.

It is conceivable that the upper surface of the bottom electrode 4 is processed into a funnel shape in order to facilitate the outflow of the metal sludge. This is not a good solution because it causes a problem of dropping and closing it.

Accordingly, the present invention has been devised to effectively solve such a problem, and an object of the present invention is to provide a novel method capable of accurately grasping the presence or absence and the amount of metal sludge deposited. A metal sludge detector for a glass melting furnace is provided.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a metal sludge measuring instrument which is inserted into a furnace body of a glass melting furnace and measures the deposition state of metal sludge deposited on the inner bottom thereof. Inserting a pair of electrodes into a tubular measuring instrument body having a closed end inserted into the furnace body, insulatingly supporting the electrodes in the measuring instrument body with an insulating material, and inserting the measuring instrument body An opening is formed on the side surface of the tip portion, and the tip of the electrode is exposed and positioned in the opening.

That is, when such a metal sludge measuring instrument is inserted into the furnace main body and the electric current is applied between its electrodes, since the metal sludge has a higher conductivity than the molten glass, the resistance value between the electrodes is measured. By doing so, not only can the presence or absence of deposition of metal sludge be detected, but also by measuring the insertion position, the deposition status can be accurately grasped at the same time.

In addition, the detector main body is configured such that the electrical conductivity is measured by closing the insertion distal end and opening the side surface of the insertion distal end, and flowing metal sludge into the inside from the side opening. Even if the insertion tip of the measuring instrument body collides with the furnace wall or the furnace bottom at the time of insertion, the electrodes can be damaged, and highly reliable detection can be performed.

[0013]

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 metal sludge measuring device 10 of a glass melting furnace according to the present invention.

As shown in the figure, a metal sludge measuring instrument 10 has a pair of rod-shaped electrodes 12, 12 inserted in parallel into a tubular measuring instrument body 11 having a closed end, and the electrodes 12, 12 are made of ceramic. And the like, and is insulated and supported in the measuring instrument main body 11 by a heat-resistant insulating material 13 such as. An opening 14 is formed in the side surface of the insertion tip of the measuring device main body 11, and the electrode 1 is provided in the opening 14.
2 and 12 are in a state where the tips are exposed. Further, a power supply circuit is connected to the other ends of the electrodes 12, 12, and a power supply unit 15 for supplying a current to the circuit and a resistance measuring device 16 for measuring an electric resistance flowing through the circuit are connected. I have.

In order to measure the presence / absence of metal sludge and the amount of deposition by the metal sludge measuring device 10 of the present invention having such a configuration, first, as shown in FIG. The tip is positioned at an arbitrary position in the furnace body 2, for example, on the bottom electrode 4 while supplying current between the electrodes 12 and 12 while inserting from the inserted insertion hole 2 c. Here, if metal sludge exists on the bottom electrode 4, the metal sludge will be
Since the current resistance value between the two electrodes 12 and 12 is rapidly reduced by flowing into the electrodes 12 and 12 from the opening 14 at the front end, the current resistance value is detected by the resistance measuring device 16 so that the part is detected. The presence of metal sludge can be reliably grasped.

Thereafter, when the tip of the measuring instrument main body 11 is moved along the slope 2a of the furnace wall as shown in FIG. 2 from such a state, the resistance value is almost changed in the portion where the metal sludge is deposited. However, since the resistance value rapidly changes (increases) when the metal sludge disappears, the presence or absence of the metal sludge in the furnace main body 2 can be determined by observing the movement of the measuring instrument main body 11 and the change in the resistance value. Of course, the amount of deposition, the deposited portion, and the like can be accurately grasped. The tip of the measuring instrument body 11 is closed and the electrodes 12 and
Since the electrode 12 is in a protected state, there is no possibility that the electrodes 12, 12 directly contact and collide with the furnace wall and be damaged.

Incidentally, the metal sludge is not necessarily in the furnace bottom,
That is, it does not always occur only on the bottom electrode 4. That is, as described above, in the initial stage of melting, a current is applied only between the main electrodes 5 and 5 to melt only the upper layer, and the glass material at the bottom is in an unmelted state, so that a layer is generated in a middle portion thereof. In some cases. Therefore, in the case of such a molten state, by moving the metal sludge measuring device 10 of the present invention along the layer boundary line, the accumulation state of the metal sludge on the layer boundary line or the like can be accurately grasped.

Since the inside and surroundings of the glass melting furnace 1 are exposed to extremely high levels of radiation, these operations are performed by remote control using a manipulator, an ITV camera and the like provided in advance in the vicinity thereof. Needless to say.

[0020]

As described above, according to the present invention, the situation such as the presence or absence of metal sludge and the amount of deposition can be accurately grasped. In addition, in a test run or a mock-up test of the glass melting furnace, since the possibility of occurrence of a short circuit accident due to the accumulation state of metal sludge can be accurately obtained in advance,
Excellent effects such as the effect of improving the furnace bottom structure can be accurately evaluated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a metal sludge measuring device of a glass melting furnace according to the present invention.

FIG. 2 is a conceptual diagram showing a method for measuring a metal sludge accumulation state using a metal sludge measuring device according to the present invention.

FIG. 3 is an explanatory view showing a configuration of a conventional glass melting furnace.

FIG. 4 is a sectional view taken along line XX in FIG. 3;

FIG. 5 is a partially enlarged view showing a portion y in FIG. 3;

[Explanation of symbols]

 2 Furnace body 10 Metal sludge measuring instrument 11 Measuring instrument main body 12 Electrode 13 Insulation material 14 Opening 15 Power supply section 16 Resistance measuring instrument

Claims (1)

[Claims] 1. A metal sludge measuring device which is inserted into a furnace body of a glass melting furnace and measures the accumulation state of metal sludge deposited therein. A pair of electrodes are inserted into the instrument body, the electrodes are insulated and supported in the measuring instrument body by an insulating material, the side of the insertion tip of the measuring instrument body is opened, and the tip of the electrode is inserted into the opening. A metal sludge measuring device for a glass melting furnace, wherein the metal sludge measuring device is positioned with the glass exposed.