JPH072441U - Glass melting furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] A glass melting furnace is used to avoid formation of a cold top in a melting tank and to form a melt in a uniform molten state and a uniform mixed state. [Structure] By heating a melting object M made of a radioactive waste F and a glass raw material G charged in a melting tank 2, a molten material in a uniform molten state is formed and stored, and the molten material flows down a nozzle. In the glass melting furnace 10 for supplying from 4 to the subsequent stage, a preliminary melting tank 11 for charging and melting the glass raw material G in a solid state is arranged in the front stage of the melting tank 2, Glass raw material G in a molten state
The formation of the cold top C is avoided by charging and the melted material in the melting tank 2 is stirred by the supplied glass raw material G.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a glass melting furnace in a radioactive waste vitrification plant or the like, and relates to a glass melting furnace for heating an object to be melted in a melting tank to maintain a uniform molten state.

[0002]

[Prior art]

 Generally, a vitrification plant is provided to vitrify radioactive waste such as high-level radioactive waste liquid generated in spent nuclear fuel reprocessing related facilities of a nuclear power plant to improve its handling. . In the vitrification plant, radioactive waste such as radioactive waste liquid and the glass material are sent into the glass melting furnace housed in the airtight chamber of the cell to be melted, and a container in which these molten mixtures are prepared is also used. It is filled in (not shown) and gradually cooled and solidified, and a series of vitrification treatments such as air pollution monitoring for leakage inspection are performed.

FIG. 2 shows a conventional example of a glass melting furnace 1. A pair of facing electrodes 3 facing inward is provided on a side wall portion 2a of a melting tank 2 made of a refractory material and charged into the inside of the melting tank 2. The object to be melted M such as tachosilicate glass is directly energized, and the entire object M is to be kept in a uniform molten state by resistance heating of the object to be melted M. In the figure, reference numeral 4 is a downflow nozzle provided at the outer bottom portion of the melting tank 2 so as to discharge the molten material inside the melting tank 2.

In FIG. 2, above the melting tank 2, a glass raw material container 5 for storing a granular or fiber-shaped solid glass raw material G, and a solid glass raw material from the glass raw material container 5 to the melting tank 2. A raw material supply means 6 for supplying G, a waste liquid storage tank 7 for storing radioactive waste liquid (radioactive waste) F, and a waste liquid supply means 8 for supplying the radioactive waste liquid F from the waste liquid storage tank 7 to the melting tank 2 are provided. It is provided. A waste liquid agitating means 9 is arranged in the waste liquid storage tank 7 so that the concentration of the radioactive waste liquid F supplied to the melting tank 2 by the waste liquid supplying means 8 is made uniform. The raw material supply means 6 is, for example, a conveyor, and while monitoring the storage amount of the melting object M in the melting tank 2, it is appropriately operated so that the storage amount becomes constant and the solid glass raw material G is supplied. It is designed to be charged into the melting tank 2. The waste liquid supply means 8 is, for example, a pump, and is appropriately operated so that the component ratio of the object M to be melted into the melting tank 2 becomes a constant ratio with respect to the solid glass raw material G. The radioactive waste liquid F is introduced into the melting tank 2.

In the vitrification plant configured as described above, in order to form a molten material in the melting tank 2, the raw material supplying means 6 and the waste liquid supplying means 8 are operated so that the melting tank 2 has an appropriate ratio. The melting target M is charged and the counter electrode 3 provided in the melting tank 2 is energized to melt the melting target M. Then, when the amount of the molten material stored is reduced by discharging the molten material from the flow-down nozzle 4, the raw material supply means 6 and the waste liquid supply means 8 are operated again to melt the molten material in the melting tank 2. M is replenished so that a certain amount of melt is always stored.

[0006]

[Problems to be solved by the device]

 However, in the above glass melting furnace 1, since the solid glass raw material G is directly charged into the melting tank 2 from above, the surface of the molten material placed inside the melting tank 2 is Then, the solid glass raw material G is deposited, and a film made of a solid glass raw material, so-called cold top C, is formed. Since solid glass is a non-conductor, it does not generate Joule heat, and when the entire surface of the molten material in the melting tank 2 is covered with the cold top C, the power input is not enough to melt the cold top C. It is not consumed, but most of it is consumed due to the temperature rise of the melt other than the cold top C, which may cause inconvenience such as overheating and damage of the counter electrode 3.

The present invention has been made in view of the above circumstances, and an object thereof is to avoid formation of the cold top C in the melting tank 2 and to form a melt in a uniform molten state. There is.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention forms and stores a molten material in a uniform molten state by heating a melting target made of a radioactive waste and a glass raw material put in a melting tank, and A glass melting furnace in which the molten material is supplied to a subsequent stage from a downflow nozzle, and a preliminary melting tank for introducing and melting a glass material in a solid state is arranged in a preceding stage of the melting tank. Is proposed.

[0009]

[Action]

 According to the glass melting furnace of the present invention, since the glass raw material in a solid state is melted by the preliminary melting tank before being introduced into the melting tank, formation of a cold top on the surface of the melt in the melting tank is avoided. Thus, it becomes possible to maintain the melt in a uniform molten state. Moreover, since the object to be melted by the preliminary melting tank is put into the melting tank in a molten state, the melt stored in the melting tank is agitated.

[0010]

【Example】

 An embodiment of the glass melting furnace according to the present invention will be described below with reference to FIG. In the present embodiment, the same reference numerals are given to the portions having the same configuration as the conventional example shown in FIG. 2, and the description will be simplified.

The glass melting furnace 10 of the present embodiment is provided with a pair of facing electrodes 3 facing inwardly on a side wall 2 a of a melting tank 2 made of a refractory material, and a glass raw material container 5 arranged above the melting tank 2. The glass raw material G and the radioactive waste liquid F are charged from the waste liquid storage tank 7 by the raw material supply means 6 and the waste liquid supply means 8, and the counter electrode is applied to the melting object M made of the mixture of the glass raw material G and the radioactive waste liquid F. 3 is maintained in a molten state by being electrically heated from 3, and the molten material is charged from the flow-down nozzle 4 formed in the lower portion of the melting tank 2 into another container (not shown) arranged below. This is common to the conventional glass melting furnace 1 shown in FIG.

However, in the glass melting furnace 10 of this embodiment, the solid glass raw material G is fed between the raw material supply means 6 for charging the solid glass raw material G from the glass raw material container 5 and the melting tank 2. The glass melting furnace 1 is different from the conventional glass melting furnace 1 in that a pre-melting tank 11 that is electrically heated while being stored to be in a molten state is provided.

Like the melting tank 2, the preliminary melting tank 11 is also a container made of a refractory material, and has a pair of facing electrodes 12 facing inwardly on its side wall 11 a. Then, the solid glass raw material G conveyed from the glass raw material container 5 by the raw material supply means 6 is put into the inside thereof and the counter electrode 12 is energized to bring the solid glass raw material G into a molten state. ing.

A molten glass flow passage 13 is provided between the preliminary melting bath 11 and the melting bath 2 to connect them to each other in a communicating state. A heater means 14 is provided for keeping the flowing glass raw material in a molten state. Then, by operating the heater means 14 while inserting the molten glass raw material in the preliminary melting tank 11 through the molten glass flow path 13, the molten glass raw material is dropped from the upper portion of the melting tank 2. Then, it is put on the melting object M stored in the melting tank 2.

According to the glass melting furnace 10 configured as described above, the glass raw material charged into the melting tank 2 is supplied by the preliminary melting tank 11 and the molten glass flow path 13 arranged in the preceding stage. Since it is charged in a molten state in advance, formation of a cold top C in the melting tank 2 is avoided, and a molten material in a uniform molten state can be stored in the melting tank 2. It is possible to effectively utilize the generated electric power to save energy, and at the same time, prevent the counter electrode 12 from overheating and maintain soundness. Further, since the glass raw material charged from the pre-melting tank 11 is in a molten state, the energy in the dropping effectively agitates the molten material in the melting tank 2, and the molten material is mixed with the radioactive waste liquid F and the glass raw material G. It is possible to form a uniform melt mixture of the above, and it is possible to make the quality of the vitrified body formed by the melt discharged from the downflow nozzle 4 uniform.

[0016]

[Effect of device]

 As described above in detail, the glass melting furnace according to the present invention produces a uniform melted product by heating the melting target made of the radioactive waste and the glass raw material put into the melting tank. A glass melting furnace that forms and stores the molten material and supplies it to a subsequent stage from a downflow nozzle, and a preliminary melting tank for pouring and melting a solid-state glass raw material is provided in the preceding stage of the melting tank. Therefore, the following effects are achieved. Since the molten glass raw material is charged into the melting tank, formation of a cold top on the surface of the molten material in the melting tank can be avoided and a molten material in a uniform molten state can be formed. Since the molten material is stirred when the molten glass raw material is put into the melting tank, a uniform molten mixture can be formed. As a result, the quality of the melt supplied from the downflow nozzle to the subsequent stage can be made uniform.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a glass melting furnace according to the present invention.

FIG. 2 is a vertical sectional view showing a conventional example of a glass melting furnace.

[Explanation of symbols]

 2 Melting Tank 3 Counter Electrode 4 Downflow Nozzle 5 Glass Raw Material Container 6 Raw Material Supplying Means 7 Waste Liquid Storage Tank 8 Waste Liquid Supplying Means 10 Glass Melting Furnace 11 Preliminary Melting Tank 12 Counter Electrode 13 Molten Glass Flow Path 14 Heater Means C Cold Top F Radioactive Waste Liquid (Radioactive waste) G Glass raw material M Melting target

Claims (1)

[Scope of utility model registration request] 1. A uniform melted melt is formed and stored by heating an object to be melted, which is made up of radioactive waste and glass raw material, which has been charged into a melting tank, and the melt is then discharged from a downflow nozzle. A glass melting furnace for supplying glass to a stage, wherein a pre-melting tank for charging and melting a glass raw material in a solid state is arranged in a preceding stage of the melting tank.