JPH0441319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder melting device that uses microwaves to melt and solidify powder, and more specifically, to a powder melting device that uses microwaves to melt and solidify powder. The present invention relates to a powder melting processing device that can process powdered materials.

The method for melting powder using microwaves is
Because heating is performed by dielectric loss based on the molecular motion of the substance that makes up the powder, the treated powder can be heated and melted from the inside evenly and efficiently, making it easier to heat and melt the powder than conventional electric heating or radiation heating. In principle, this method is much superior to that of the previous method. For this reason, it is used for various purposes in many industrial fields, but recently it has been applied to industrial waste treatment, where waste discharged from various industrial facilities and nuclear facilities is heated and melted by microwave irradiation. , a method of vitrifying and solidifying waste using silicon dioxide contained in waste is attracting attention.

Various types of melt processing equipment have been considered for this purpose. For example, as one such apparatus, a powder melting processing apparatus is known which includes a powder melting section consisting of a cylindrical container constituting a microwave cavity resonator.

A schematic configuration of the main parts of this type of powder melting processing apparatus can be shown in FIG. That is, a cylindrical container 1 forming a microwave cavity resonator is composed of metal cylinders 3 and 4 with high conductivity that are joined or separated at a flange overlapping portion 2, and the cylindrical container 1
A microwave waveguide 7 that guides the microwave emitted from the oscillator 6 into the cylindrical container 1, a matching mechanism 8 that performs matching during resonance, and a powder material 9 are disposed on the top of the oscillator 6.
It is connected to a powder introduction pipe 10 that introduces powder. When microwaves are irradiated from the oscillator 6, the interior of the cylindrical container 1 resonates in a mode that produces the strongest electric field.

In this powder melting processing apparatus, a cylindrical container 1
After introducing a predetermined amount of the powder 9 into the powder 9, when microwave irradiation to the powder 9 is started, the powder 9 is heated and melted, and when it is left to cool, the particles contained in the powder 9 are melted. Depending on the components contained in the powder, such as silicon dioxide (if the powder 9 is waste from a nuclear facility), the powder 9 becomes vitrified or petrified and solidifies. This solidified powder 9 is separated from the metal cylinder 3 together with the cylinder 4, and is disposed of.

This device is considered to be the most excellent waste treatment device in terms of its ability to process a large amount of powder at one time. However, when trying to melt radioactive powder such as radioactive incineration ash obtained by incinerating waste at nuclear power plants, nuclear fuel processing plants, facilities that use radioisotopes, etc. using the above melting processing equipment, the following occurs. A big problem arises.

First, in the conventional powder melting processing apparatus, when the powder 9 is introduced into the cylindrical container 1 and then irradiated with microwaves, the cylindrical container 1 is heated by the by-product gas generated during the microwave irradiation. It becomes a pressure state and the powder 9
may be scattered or blown out from the flange portions 2 of the cylinders 3 and 4 or the connecting portions of the microwave introduction tube 7 and the powder introduction tube 10, contaminating the surrounding area. The fact that such powdery material 9 comes out is that the powdery material 9
If it is waste from a nuclear facility, it is extremely dangerous and poses a major safety problem.

Furthermore, in the case of radioactive powder (incineration ash), its particle size is small and it easily floats or scatters. Therefore, it is quite difficult to transport such dangerous radioactive powder from the incinerator to the melting processing equipment without scattering ash into the surrounding area.

The present invention has been made in view of these points, and its purpose is to eliminate the scattering and blowing out of the powder material outside the melting processing equipment during microwave irradiation of the powder material, and to further improve safety. An object of the present invention is to provide a powder melting processing apparatus.

The present invention achieves this object in a powder melting processing apparatus using a cylindrical container as a microwave cavity resonator, in which a powder introduction pipe is tangentially connected to the peripheral wall of the cylindrical container, and one end is connected to the top of the cylindrical container. An exhaust pipe connected to an exhaust device is installed through the cylindrical container, and a substantially funnel-shaped partition wall is provided in the middle of the cylindrical container to create a negative pressure state inside the cylindrical container. The powder is introduced as a swirling airflow into the cylindrical container from the body storage part, and is allowed to settle along the peripheral wall of the cylindrical container and the upper surface of the partition wall, and the deposited powder is irradiated with microwaves under negative pressure to melt it. It is characterized by the following structure.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figures 2 and 3 (sectional view taken along line A-A in Figure 2) are
This is an explanatory diagram showing one embodiment of the present invention. Similar to FIG. 1, a cylindrical container 1 is constructed by removably connecting cylinders 3 and 4 at a flange overlapping portion 2. FIG.
Further, a microwave waveguide 7 for introducing microwaves from an oscillator 6 is connected to the upper part of the cylindrical container 1, as in FIG. 1.

On the other hand, one end of the powder introduction pipe 10 is connected to the cylindrical container 1
is tangentially connected to the upper peripheral wall of the powder storage section 11, and the other end thereof is disposed within the powder storage section 11. Further, a substantially funnel-shaped partition wall 12 is provided in the middle of the cylindrical container 1, and a matching mechanism 8 is attached to the lower part of the partition wall 12. Further, an exhaust pipe 13 is installed passing through the top of the cylindrical container 1, and the other end side of the exhaust pipe 13 is connected to an exhaust device 14 such as a turbo fan or a blade fan. The exhaust port of this exhaust device 14 is connected to a dust collector 16 via a pipe 15, and the dust collector 16 completely collects a small amount of powder accompanying the exhaust air. The powder is returned to the powder storage section 11 via the powder storage section 11.

Next, the operation of the powder melting processing apparatus having the above configuration will be explained.

In this processing device, when the exhaust device 14 is started, the exhaust pipe 13, the cylindrical container 1, the powder introduction pipe 1
The inside of the system composed of 0, etc. becomes a negative pressure state, and the powder 9 in the powder storage section 11 is sucked into the cylindrical container 1 through the powder introduction pipe 10. Powder introduction pipe 1
Since one end of the powder 9 is connected to the peripheral wall of the cylindrical container 1 in a tangential direction, the powder 9 sucked into the cylindrical container 1 flows inside as a swirling air current and is subjected to the action of centrifugal force. It descends (sinks) along the upper peripheral wall of the cylindrical container 1 and the upper surface of the funnel-shaped partition wall 12, and falls to the lower part of the cylindrical container 1 through the opening of the funnel-shaped partition wall 12. With the predetermined amount of powder 9 deposited in the cylindrical container 1, the exhaust device 14 is left in operation,
When microwaves are introduced from the microwave waveguide 7 and resonated together with the matching mechanism 8, the cylindrical container 1
A strong electric field is generated inside the The powder 9 in the cylindrical container 1 is heated and melted by this electric field. At this time, dusting occurs due to disturbances such as generation of by-product gas, and a part of the powder 9 is transferred to the funnel-shaped partition wall 12.
Even if it returns to the upper side, it will be caught in the swirling air current,
Due to the action of the centrifugal force, it sinks again along the peripheral wall of the cylindrical container 1 and the upper surface of the partition wall 12 and falls to the lower part of the cylindrical container 1.

When the powder 9 in the cylindrical container 1 is irradiated with microwaves for a predetermined time and then left to cool, the powder 9 (molten material) in the cylindrical container 1 becomes glass-like or rock-like. and solidify. The solidified powder 9 is disposed of or stored together with the cylinder 4 that is separated from the cylinder 3.

It should be noted that the airflow discarded through the exhaust pipe 13 hardly contains any powder 9, but even if it does, it will be collected by the dust collector 16.
The powder is returned to the powder storage section 11 and subjected to the above-mentioned processing steps again. Further, in the process of sucking the powder 9 through the powder introduction pipe 10, it can be expected that undesirable heavy objects such as large metal pieces contained in the powder 9 will be selectively removed. In this case, the remaining large metal pieces etc. will be treated by another treatment method.

4 and 5 are schematic explanatory diagrams of other embodiments of the present invention, and the same parts as in FIG. 2 are denoted by the same reference numerals, and the explanation thereof will be omitted. The feature of these embodiments is that the cylinder 3 is made of cylinders 3a and 3b having different diameters.
A partition wall 12 is fixed to the lower part of the cylinder 3a, and the partition wall 12 is fixed to the upper part of the cylinder 3b. According to such a configuration, the work of attaching the partition wall 12 to the inner circumferential surface of the cylinder 3 becomes easy.

In each of the above embodiments, a turbo fan, a blade fan, etc. are used as the exhaust device 14 (these are omitted in FIGS. 4 and 5), but the present invention is not limited to this. Instead, it may be a fan such as a multi-blade fan or a propeller fan, a blower such as a turbo blower or a roots blower, or an ejector such as a water ejector or a steam ejector. Further, the present invention does not require the provision of the dust collector 16, and the exhaust gas obtained through the exhaust pipe 13 may be blown directly into the atmosphere or into an incinerator for incinerating waste. good. Further, a discharge valve may be provided at the bottom of the cylindrical container 1 in order to discharge the powder 9 after the melting process.

As explained in detail above, the powder melting processing apparatus of the present invention suctions and introduces the powder as a swirling airflow by creating a negative pressure inside the cylindrical container in which the funnel-shaped partition wall is provided. The liquid is collected by sedimentation along the peripheral wall of the cylindrical container and the upper surface of the funnel-shaped partition wall, and is allowed to fall to the lower part of the cylindrical container. For this reason, it is possible to transfer the powder from the powder storage section without scattering the powder to the outside, but also by-product gas is generated during microwave irradiation, and part of the powder is removed by dusting. Even if it returns above the funnel-shaped partition, it is captured by the swirling airflow and returns to the lower part of the cylindrical container, and is not scattered to the outside. Therefore, it can be said to be extremely safe without contaminating the surrounding area.

[Brief explanation of drawings]

Fig. 1 is a conceptual explanatory diagram of a known powder melting processing apparatus, Fig. 2 is an explanatory diagram showing an embodiment of the present invention, Fig. 3 is a sectional view taken along line AA in Fig. 2, Fig. 4, and FIG. 5 is an explanatory diagram showing the outline of other embodiments of the present invention. 1... Cylindrical container, 2... Flange portion, 3, 4...
... Cylinder, 6 ... Oscillator, 7 ... Microwave waveguide, 8 ... Matching mechanism, 9 ... Powder, 10
... Powder introduction pipe, 11 ... Powder storage section, 12
... Funnel-shaped bulkhead, 13 ... Exhaust pipe, 14 ... Exhaust device, 16 ... Dust collector.

Claims (1)

[Claims] 1. In a powder melting processing apparatus using a cylindrical container as a microwave cavity resonator, a powder introduction pipe is tangentially connected to the peripheral wall of the cylindrical container, and an exhaust pipe is connected to the top with one end connected to an exhaust device. A pipe is inserted through the cylindrical container, and a substantially funnel-shaped partition is provided in the middle of the cylindrical container to create a negative pressure inside the cylindrical container, thereby transferring the powder from the powder storage section into the cylindrical container. The powder is introduced as an airflow into the cylindrical container, is allowed to settle along the peripheral wall of the cylindrical container and the upper surface of the partition wall, and is melted by irradiating the deposited powder with microwaves under negative pressure. Powder melting processing equipment.