JP2002214391A - Calcined body breaking method of molten glass liquid surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new calcined body breaking method of a molten glass liquid surface capable of certainly and speedily breaking and removing a calcined body produced on the molten glass liquid surface. SOLUTION: A purge line 16 is connected to a glass bead supply pipe 13, and glass beads B are supplied from the glass bead supply pipe 13 into a glass melting furnace 1 and simultaneously compressed air is blown from the purge line 16 to strongly collide the glass beads B against the molten glass G liquid surface. Thus, the calcined body S on the molten glass G liquid surface can be certainly and speedily broken and removed, and inconvenience such as degradation of fluidity due to abnormal temperature rising of the molten glass G can be avoided.

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 breaking and removing a calcined body formed on a liquid glass surface of the glass melting furnace. The present invention relates to a method for destroying a calcined body.

[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.
Is melted together with a glass material (glass beads, glass cartridge, etc.) made of borosilicate glass or the like at a high temperature and is a corrosion-resistant stainless steel container called a canister c. It is planned to stabilize it as a vitrified body after being packed inside, and then cool it naturally for a certain period of time before disposing of it deep underground.

[0003] A glass melting furnace 1 used for such vitrification includes a furnace main body 2 made of a refractory brick as shown in the figure.
And a pair of main electrodes 5 and 5 and auxiliary electrodes 6 and 6 on the side walls.

[0004] First, a high-level radioactive waste liquid and a glass raw material are charged at a predetermined ratio from a charging port 7 provided on the ceiling wall of the furnace main body 2, and an electric current is applied between the main electrodes 5 and 5 to cause a joule. By generating heat, the charged glass material is heated to a high temperature, and the high-level radioactive liquid waste and the glass material are sufficiently melted in the furnace to form a molten glass G. Next, when the amount of the molten glass G in the furnace reaches a predetermined amount, electricity flows between the auxiliary electrodes 6 and 6 located under the furnace and between the bottom electrode 4 and the main electrodes 5 and 5 to lower the glass material in the lower layer. Is melted, and the falling nozzle 8 extending from the falling hole 3 is heated by the surrounding electric heating coil 9 to continuously flow the molten glass G inside into the lower canister c joined by the joining device 10 to reduce the glass. It is designed to be housed as a solid.

The gas generated in the melting furnace 1 is exhausted from the exhaust port 11 as off-gas,
The radioactive material is completely collected and removed by an A filter or the like, rendered harmless, and then released into the atmosphere.

[0006]

If the molten glass G in the furnace is reduced by sequentially flowing the molten glass G in this way, the flow is temporarily stopped, and the inlet is reduced by the reduced amount. 7, a new glass raw material and waste liquid are added and heated and melted. When the new waste liquid and glass raw material are dropped, the surface layer of the molten glass G is rapidly cooled and the liquid surface becomes thin. A film-like calcined body S may be formed.

The mechanism of generation of the calcined body S and the details of its components are unknown at present, and further experiments and studies will be required in the future. When generated on the liquid surface, the heat of the molten glass G in the furnace hardly escapes to the plenum (gas phase) P side, and the temperature of the molten glass G in the furnace, particularly near the liquid level, rises sharply and melts. The disadvantage that the fluidity of the glass G is deteriorated occurs.

That is, the temperature of the molten glass G is constantly monitored by a plurality of temperature sensors, and a control device controls the current values of the electrodes 5 and 5 in accordance with signals from the temperature sensors. When the calcined body S is generated and the heat hardly escapes from the molten glass G and the temperature rises more than necessary, the temperature sensor malfunctions, and the current values of the electrodes 5 and 5 decrease more than necessary. As a result, the viscosity of the molten glass G increases, and the glass flowability may be significantly deteriorated.

Accordingly, the present invention has been devised to effectively solve such a problem, and its object is to ensure that even if a calcined body causing such inconvenience occurs, it can be reliably and promptly made. An object of the present invention is to provide a novel method for destroying a calcined body of a liquid surface of a molten glass which can be destroyed and removed.

[0010]

According to the present invention, there is provided a method for destroying a calcined body formed on a liquid surface of a molten glass in a glass melting furnace.
A purge line is connected to a glass bead supply pipe provided at a raw material supply port of the glass melting furnace, and glass beads are supplied from the glass bead supply pipe into the glass melting furnace while compressed air is blown from the purge line. The beads are supplied while vigorously colliding with the liquid surface of the molten glass.

[0011] With this, the calcined body formed on the liquid surface of the molten glass can be reliably destroyed and removed at the same time as the supply of the glass beads. Can be implemented.

According to a second aspect of the present invention, the lower end of the glass bead supply pipe extends to near the liquid surface of the molten glass, and a straight line is formed from the connection part of the purge line to the lower end. Since the glass beads can be sent directly to the liquid side of the molten glass, the glass beads can be more effectively collided with the calcined body, which can be destroyed and removed.

[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 a glass melting furnace 1 according to the method of the present invention.
1 shows an embodiment in the vicinity of an upper raw material supply pipe 12.

As shown, the raw material supply pipe 12 is
Flange 7a of inlet 7 formed on the ceiling wall of furnace body 2
The glass raw material to be molten glass and the high-level radioactive liquid waste are dropped from above and supplied into the furnace main body 2.

That is, the raw material supply pipe 12 is provided with a glass bead supply pipe 13 extending from a glass raw material supply section (not shown) and a waste liquid supply pipe 14 extending from a waste liquid tank. Tube 13
Glass beads B with a particle size of a few mm
However, the high-level radioactive waste liquid is supplied independently from the waste liquid supply pipe 14.

A glass cartridge supply pipe 15 for supplying a glass cartridge C, which is also a glass raw material, is also connected to the raw material supply pipe 12.
The high level radioactive waste liquid is impregnated into the glass cartridge C while being sent to the side of the furnace body 2 together with the waste liquid.
It is designed to fall and supply sequentially inside.

Here, in the present invention, the glass bead supply pipe 13 for supplying the glass beads B penetrates the side of the raw material supply pipe 12 obliquely downward as shown in FIG.
The lower end portion is in a linear state extending further below the lower end of the raw material supply pipe 12 to near the liquid surface of the molten glass G, and guides the glass beads B straight to the liquid surface side of the molten glass G to supply the glass beads B. It is supposed to.

Further, a purge line 16 is connected to the glass bead supply pipe 13, and air for purging, that is, high-pressure compressed air is arbitrarily blown into the glass bead supply pipe 13 to drop its own weight under its own weight. The glass beads B are further accelerated to collide with the liquid surface of the molten glass G.

Therefore, the glass beads B are again purged from the glass bead supply pipe 13 together with the new waste liquid into the furnace main body 2 in which the volume of the molten glass G is reduced by manufacturing the vitrified body as described above. If the liquid surface of the molten glass G is vigorously sprayed with the air, the calcined body S formed on the liquid surface of the molten glass G is immediately destroyed by the impact of the collision of the glass beads B, and the molten glass Since the molten glass G disappears after being mixed with G, the heat of the molten glass G can be reliably released to the plenum P side on the liquid surface without accumulating, that is, as originally designed.

That is, conventionally, the glass beads B
Like the waste liquid, it is supplied so as to roll down the glass bead supply pipe 13 mainly due to its own weight, so that there is no impact that destroys the calcined body S.
In this way, the lower end of the glass bead supply pipe 13 is made linear toward the liquid surface side, and the glass beads B are accelerated by the purge air and supplied while being vigorously collided, so that the glass raw material is supplied simultaneously with the supply of the glass raw material. The fired body S can be effectively destroyed and removed.

As a result, the temperature of the molten glass G in the furnace main body 2 does not rise abnormally, so that inconveniences such as the above-mentioned inferior flow due to an increase in viscosity due to the malfunction of the temperature sensor are reliably avoided. And a good vitrification operation can be performed.

As described above, as a raw material supply method, in addition to a method of supplying from the glass bead supply pipe 13 and the waste liquid supply pipe 14, a method of supplying from the glass cartridge supply pipe 15 and a method of using both are used. However, in any of the methods, the object of the present invention can be reliably achieved by vigorously spraying the glass beads B from the glass bead supply pipe 13 onto the liquid surface side of the molten glass G at the time of supplying the raw material.

In the figure, reference numeral 17 denotes a water supply pipe for supplying water into the furnace main body 2 as required, and arbitrarily diluting the waste liquid in the furnace main body 2.

[0025]

In summary, according to the present invention, since the calcined body generated on the liquid surface of the molten glass can be reliably destroyed and removed simultaneously with the supply of the glass raw material, the flow caused by the abnormal rise of the molten glass temperature Excellent effects such as inconvenience such as deterioration of the properties can be avoided beforehand.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a method for breaking a calcined body of a molten glass liquid surface according to the present invention.

FIG. 2 is an explanatory view showing the structure of a conventional glass melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass melting furnace 2 Furnace main body 12 Raw material supply pipe 13 Glass bead supply pipe 14 Waste liquid supply pipe 15 Glass cartridge supply pipe 16 Purge line B Glass beads C Glass cartridge G Molten glass S Calcined body

Claims (2)

[Claims] In a method for destroying a calcined body formed on a liquid level of a molten glass in a glass melting furnace, a purge line is connected to a glass bead supply pipe provided at a raw material supply port of the glass melting furnace. The glass beads are supplied from the bead supply pipe into the glass melting furnace at the same time as the compressed air is blown from the purge line so that the glass beads vigorously collide with the molten glass liquid level. Method of destroying the calcined body. 2. The method according to claim 1, wherein a lower end portion of the glass bead supply pipe extends to near a liquid level of the molten glass, and a downstream side from the purge line connection portion is formed linearly. Item 4. The method for destroying a calcined body of a liquid surface of a molten glass according to Item 1.