JPH0260613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heating and melting solidification of glassy powder, particularly,
This invention relates to a device for melting and solidifying waste containing radioactive materials generated at nuclear power plants or incineration residue of general industrial waste.

In recent years, the treatment of industrial waste contaminated with radioactive substances, heavy metals, and other contaminants has become a problem, and when waste is incinerated from now on, contaminants are often concentrated in the incineration ash that remains after incineration. ,
Its processing and storage have become problems. In addition, the incineration ash generated after incinerating organic materials contaminated with these pollutants contains a large amount of silicon compounds, which melt when heated to high temperatures and solidify into glass or rock shapes when further cooled. Therefore, this operation is known as a method for obtaining a solidified product suitable for preventing the diffusion of pollutants.

As mentioned above, various methods of heating and melting the incinerated ash have been studied to prevent the diffusion of pollutants by heating and melting the incinerated ash and then cooling and solidifying it. Among these, the dielectric heating method using microwaves is known to have excellent characteristics such as thermal efficiency and operability.

However, although the dielectric heating method using microwaves has various features, it has one serious drawback. In other words, glassy powder such as the above-mentioned incineration ash is an almost completely poor conductor electrically in the low temperature range at the initial stage of heating, so that efficient dielectric heating is performed as a whole, but once the temperature exceeds a certain point, Electrical conductivity appears, resulting in the surface reflecting microwaves. Therefore, when heating a large amount of incinerated ash, there is a drawback that only the portion near the surface is heated. Therefore, if you try to supply a large amount of incinerated ash at once to melt and solidify it, only the surface part of the solidified incinerated ash will melt, and the inside will remain incompletely melted and become a fused powder containing bubbles. , the problem arises that the solidified material lacks mechanical strength and breaks and scatters. There is a concern that the solidified material in this state may elute contaminants.

In order to eliminate the above drawbacks, we focused on the electrical conductivity of the glassy material at high temperatures, and heated it using microwaves in the low temperature region where there is almost no electrical conductivity, and in the high temperature region where there is electrical conductivity. After reaching the temperature, the glassy material is melted by resistance heating by passing electricity directly through it.
A so-called two-stage heating method is conceivable, which results in a completely homogeneous melt.

The purpose of the present invention is to provide a device for melting and solidifying glassy powder that can rationally realize this two-stage heating method, and is particularly focused on the simplicity of the device, ease of operation, safety, and prevention of contaminants. It has a structure that takes into account the prevention of leakage outside the melting furnace system and the preservation of solidified materials.
In other words, the present invention maintains the structure of the microwave heating device, uses the container of the melting section as one electrode for direct energization, and adds an energizer that places the other electrode inside this container, thereby achieving uniformity throughout. This allows resistance heating to be carried out, and the container can be used as a storage container as it is after cooling.

Next, the present invention will be described by way of examples with reference to the drawings. 1, 2 and 3, the device according to the invention has an upper body 1 and a lower body 2. In FIGS. A microwave waveguide 3 is coupled to the upper body 1 and connected to a microwave generator (not shown).
The upper body 1 and the lower body 2 are detachably connected at a connecting portion 4. An electrode rod 5 is supported by the upper lid 1a from the upper part of the upper body 1 and is arranged to be movable up and down. The dielectric heating is set back upwards so as not to cause microwave discharge, and when energized, the tip moves down so that it connects to the glassy material. Incineration ash 6 is accommodated in the lower body 2. The upper and lower bodies 1 and 2 are made of metal plates such as iron, and form a microwave cavity resonator. The electrode rod 5 is made of a heat-resistant material such as carbon-based material. The electrode rod is electrically insulated from the upper lid 1a.

As shown in FIG. 2, when the vibrating rod 5 is lowered and the incinerated ash 6 is energized and heated, the energizing circuit 7 is connected to the electrode rod 5.
and a flange 2a on the connecting portion 4 of the lower body 2. FIG. 3 shows a state in which the heated ash 6 after melting has become a vitrified solidified product 8, and the lower body 2 is used as a storage container with a lid 9 placed thereon.

Note that the actual device is equipped with an exhaust pipe, an incinerated ash supply device, a see-through port, an infrared thermometer, etc., but these are not particularly related to the configuration of the present invention, so illustrations thereof are omitted.

Next, a standard operating procedure for melting and solidifying incineration ash using the apparatus of the present invention will be described.

1 Position the electrode rod 5 on the upper part of the upper body 1 (Fig. 1), 2 Supply the incinerated ash 6 to the lower body 2, 3 Emit microwaves from the microwave waveguide 3 to perform dielectric heating, 4 Predetermined After heating the incinerated ash 6 to a temperature of The incinerated ash 6 is heated by resistance heating. 6 Since the volume of the incinerated ash 6 is greatly reduced after heating and melting, the incinerated ash is further supplied continuously or intermittently and heated with electricity. In this case, microwave heating and direct current heating are used alternately as necessary. 7. After the incineration ash 6 is melted and sufficiently filled in the lower body 2, it is removed from the upper body 1. 8. Incineration of the molten and solidified ash The ash is stored in the lower body 2, a lid 9 is placed on it, and the lower body 2 is used as a storage container (Fig. 3).
Although the case where the electrode rod is vertically lowered from the upper body 1 has been described, it is also possible to insert the electrode rod in an oblique direction from the side wall portion of the upper body 1 and bring it into contact with the glassy powder and apply electricity to heat and melt it.

As explained above, according to the present invention, incineration ash containing pollutants can be completely melted and solidified by two-stage heating, and the structure of the device is simple, and ease of operation and safety are ensured. Furthermore, prevention of leakage of contaminants outside the melting furnace system and complete preservation of solidified material are achieved. Furthermore, in the present invention, an inexpensive material such as iron is used for the lower body as a container for the molten solidified material, and this is also used as one of the electrodes, so the structure is simple and low cost. can.

Although this device was invented for the purpose of melting glassy powder such as incineration ash, the application is not limited to this, and can be used for glassy powder slurry, glassy powder containing solids, etc. Also, vitreous material may be intentionally added to materials with little vitreous material.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the apparatus according to the present invention, FIG. 2 is a cross-sectional view of the apparatus according to the present invention during resistance heating, and FIG. 3 is a cross-sectional view of the solidified product according to the present invention in a stored state. DESCRIPTION OF SYMBOLS 1... Upper body, 2... Lower body, 3... Microwave waveguide, 4... Connection part, 5... Electrode rod, 6... Incineration ash,
7... Current-carrying circuit, 8... Melted and solidified material, 9... Lid.

Claims (1)

[Claims] 1. An apparatus for melting and solidifying vitreous powder, comprising: an upper body; a lower body that is detachable from the upper body and accommodates the vitreous powder; a microwave supply means for heating and melting the vitreous powder; It comprises an electrode rod capable of contacting the glassy powder housed in the lower body, and a circuit means capable of applying a voltage between the electrode rod and the lower body, and the microwave supply means 1. An apparatus for melting and solidifying glassy powder, characterized in that the powder is heated and then heated and melted using the electrode rod.