JPH0262038B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microwave incinerator used to incinerate and reduce the volume of powder such as ion exchange resin and granular radioactive waste using microwaves. It is.

[Prior art] In the past, for example, various types of radioactive waste generated from nuclear power facilities were initially stored as they were in drum pipes, but as the amount generated increased, the amount stored also increased dramatically, and the volume was reduced. It has come to be hoped that this will become a reality. Therefore, a technique has been proposed in which the moisture attached to or contained in powder or granular waste is heated and treated using microwave energy.

[Problems to be Solved by the Invention] However, this microwave incineration method had the following problems.

(1) In order to perform incineration economically, it is necessary to charge a considerable amount of materials to be burned into a furnace and process them all at once, but the layer becomes thicker, making it difficult for microwaves to reach inside.

(2) Residues of combustible materials connect with each other to form clinker, making microwave irradiation even more difficult.

(3) When the layer of combustible material becomes thick, the supply of air or oxygen becomes insufficient, making uniform incineration difficult.

(4) When using a stirrer, the stirrer is made of metal and is exposed in the furnace, so there is a risk of it being burned out by microwaves. Furthermore, the stirrer requires sufficient cooling. The present invention solves the above-mentioned problems of the conventional ones, and by sufficiently stirring the combustible material and supplying sufficient air or oxygen into the layer, the combustible material is combusted uniformly and efficiently. However, an object of the present invention is to provide a microwave incinerator that can prevent overheating and burnout of a stirrer.

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides a rotating system in which a microwave waveguide opens in a cylindrical furnace shell and plunges into the furnace shell from the top plate. In a microwave incinerator that stirs and incinerates the materials charged into the furnace body using a stirrer equipped with stirring blades at the lower end of the shaft, the rotating shaft of the stirrer is The present invention provides a microwave incinerator characterized in that the incinerator is supported to be movable up and down, and air or oxygen is supplied into the combustible material through the rotating shaft. Uniform incineration is achieved by maintaining fluidity until the material is sufficiently incinerated, irradiating microwaves evenly, and distributing air or oxygen sufficiently.On the other hand, the air or oxygen flowing inside the shaft The stirrer can be sufficiently cooled to prevent overheating and burnout.

[Example] Embodiments of the present invention will be described using the drawings.

First, referring to FIG. 1 which shows the principle of the present invention,
The furnace body 1a of the microwave incinerator has a vertical cylindrical shape, and the top plate is connected with a combustion material supply pipe 2, a microwave waveguide 3, and an exhaust gas duct 5, and a hollow rotating shaft 7 passes through it on the central axis. ing. An air or oxygen duct 9 for combustion of combustible materials, a nitrogen duct 10 for fire extinguishing, and an incineration ash discharge duct 11 are connected to the pipe joint 7a at the upper end of the hollow rotating shaft 7 via valves. An incinerated ash discharge duct 4 equipped with a valve is connected to the bottom plate of the furnace body 1a. A stirrer 6 having horizontal blades is provided at the lower end of the hollow rotary shaft 7 extending to the lower end of the furnace body.

The stirrer 6 can be provided not only at the lower end of the hollow rotating shaft 7 as shown in the figure, but also above it.

Above the furnace body 1a of the hollow rotating shaft 7 is a drive mechanism 8.
is provided. The hollow rotary shaft 7 is not only rotated by this drive mechanism 8, but also moved up and down by suitable means, and its rotation and vertical movement are for effective stirring and protection of the stirring device (protection from microwaves). Therefore, it is controlled by appropriate means.

When waste, for example powder such as ion exchange resin or granular radioactive waste, is supplied from the supply pipe 2 and deposited to an appropriate depth on the bottom plate of the furnace body 1a, the drive mechanism 8
The hollow rotary shaft 7 rotates due to the action of , and simultaneously starts vertical movement by another suitable means. The combustible material is sufficiently stirred by the stirrer 6 and heated by microwaves (915 to 2400 MH) introduced from the waveguide 3. Initially, the combustible material is dried under a nitrogen purge condition. It is dry distilled, then combusted and incinerated by supplying air or oxygen. Air or oxygen passing through the hollow rotating shaft 7 cools the hollow rotating shaft 7, and the stirrer 6 stirs the material to be burnt to prevent the formation of clinker and achieve uniform incineration.

When the incineration is finished, nitrogen is supplied from the hollow rotary shaft 7 to extinguish the fire and cool it down, and the incinerated ash is discharged from the incinerated ash discharge duct 4. The ash that has not been completely discharged is removed from the hollow rotating shaft 7.
The ash is sucked and discharged upward using the incineration ash discharge duct 11.

Next, referring to FIG. 2 which shows a specific embodiment of the present invention, the furnace body 1a of the incinerator is cylindrical with an open top end, and a heat insulating wall 1b is provided around the periphery.
The top plate 1c of the furnace body includes a combustible material supply pipe 2, a microwave waveguide 3, an exhaust gas duct 5, and a cylindrical frame 1 for suspending the microwave incinerator 1 from the factory building.
d is attached, and a hollow rotating shaft 7 passes through the center of the top plate 1c. A hollow stirrer 6 is fixed to the lower end of the hollow rotating shaft 7 in a horizontal direction with respect to the hollow rotating shaft 7. A plate 6a is further fixed to the bottom surface of the stirrer 6. The hollow rotating shaft 7 is
It passes through a drive mechanism 8 mounted on a base plate 1e fixed to the upper end of the cylindrical frame 1d and ends at a pipe joint 7a. The drive mechanism 8 consists of an electric motor 8b mounted on a base plate 1e, and a driven part 8a that is driven from a downwardly protruding shaft via a transmission device, and the driven part 8a is rotated through a spline or the like. It can be transmitted to a hollow rotating shaft. A disk 7b is fixed to the upper part of the hollow rotating shaft 7 inside the cylindrical frame 1d, and this disk 7b is connected to a handle 15a, a connecting pin 15b, and a fork 15c that are rotatably fixed to the outside of the lower end of the frame 1d. It can be moved in the vertical direction by a link device 15 consisting of the following. Therefore, by operating the handle 15a, the stirrer 6 can be moved up and down with an appropriate stroke to stir the combustible material in the vertical direction as well.

Further, the top plate 1c of the furnace body 1a is further provided with a pressure relief lid for releasing excessive pressure in the furnace body, a level meter for detecting the level of combustible materials in the furnace body, and a viewing window. .

An incineration ash discharge duct 14 is attached to the bottom plate of the furnace body 1a, and almost all of the incineration ash can be discharged. Depending on the type of incinerated ash, it can also be sucked and discharged from the discharge duct connected to the pipe joint 7a, as described with reference to FIG. Similarly to FIG. 1, an air or oxygen duct and a nitrogen duct are also connected to the pipe joint 7a.

By raising and lowering the stirrer 6, the stirrer 6 can be kept buried in the material to be burnt, and overheating due to concentration of microwaves can be prevented.

[Effect of the invention] By configuring as described above, the present invention has the following effects:
An incinerator with a simple structure can effectively heat radioactive waste such as ion exchange resin that contains a large amount of water.
It is possible to uniformly incinerate and reduce the volume without producing clinker, and it is also possible to prevent overheating of the stirrer.

To explain in more detail, the use of microwaves as a heating means simplifies the structure of the furnace, makes it possible to effectively heat materials such as ion-exchange resins that contain a lot of water, and makes it easy to start, stop, and control heating, making it possible to handle any situation It is possible to respond immediately to any situation, and it is also possible to dispose of a large amount of waste in a relatively short period of time. In addition, the stirrer keeps the material to be combustible in a constant state of fluidity and evenly irradiates it with microwaves to ensure uniform combustion, while supplying air or oxygen from the hollow rotating shaft to the shaft. Achieve cooling and combustion acceleration. Moreover, the strong stirring force can crush the clinker that is about to be produced. Furthermore, the hollow rotating shaft also has secondary effects such as supplying nitrogen to promote extinguishing of combustible materials, and can also be used to suck out incinerated ash that cannot be discharged downward.

As mentioned above, the microwave incinerator of the present invention includes:
Since it significantly improves the treatment of powdered and granular radioactive waste such as ion exchange resins, it will greatly contribute to the field of nuclear power utilization, whose development has been restricted due to the lack of established radioactive waste treatment technology. .

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing the principle of the present invention, and FIG. 2 is a longitudinal sectional front view of an embodiment of the present invention. 1... Microwave incinerator, 1a... Furnace body, 1b
...insulation wall, 1c...top plate, 1d...frame,
1e... Base plate, 2... Combustible material supply pipe, 3... Microwave waveguide, 4... Incineration ash discharge duct, 5...
Exhaust gas duct, 6... Stirrer, 6a... Board,
7...Hollow rotating shaft, 7a...Pipe joint, 7b...Disc, 8...Drive mechanism, 8a...Driven part, 8b...
...Electric motor, 9... Air or oxygen duct, 10...
Nitrogen duct, 11...Incineration ash discharge duct, 15...
...Link device, 15a...Handle, 15b...
Connection, 15c...fork.

Claims (1)

[Claims] 1 A microwave waveguide opens in the cylindrical furnace shell, and the microwave is charged into the furnace shell using a stirrer equipped with stirring blades at the lower end of a rotating shaft that protrudes into the furnace shell from the top plate. In a microwave incinerator that stirs and incinerates combustible materials, the rotating shaft of the stirrer is supported to be movable up and down, and air or oxygen is supplied into the combustible materials through the rotating shaft. A microwave incinerator characterized by: