JP2003243145A - High-temperature microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-temperature microwave oven easily made large-scale with microwave as heat source and a support and a shelf board member for use in it. <P>SOLUTION: With the high-temperature microwave oven using microwave as a heating source, an object for heating, a shelf board member, a heat insulating material, a support body, a waveguide, and a metal casing are arranged in that order from the inside, the metal casing is provided with the waveguide, the support body is fitted with the shelf board member on which the object for heating is put, the heat insulating material is arranged to surround the object for heating, the heat insulating material is supported by the support, and the support and the shelf board member are made of a non-metal and inorganic material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave heating furnace for high temperature and a support and a shelf board member used therein.

[0002]

2. Description of the Related Art Microwave heating is a method in which microwave electric power is absorbed by an object to be heated of a dielectric and self-heats from the inside of the object to be heated of the dielectric.

Therefore, compared with the conventional heating method using heat conduction or radiation, which uses gas, electric resistance or the like as a heat source, microwave heating enables rapid heating and has a high thermal efficiency, so that heat treatment is performed in a short time. It can be performed.

Applying this principle, microwave heating is
It is widely used in rubber heat vulcanizers and wood adhesive dryers.

In addition to these low temperature applications, Japanese Patent Publication No. 59-25937 discloses a microwave heating furnace for firing ceramics, ceramics and the like for high temperature applications. A firing furnace for firing using a microwave oven is disclosed in JP-A-7-318.
No. 262 publication. In such high temperature applications, it is necessary to surround the object to be heated with a heat insulating material so as to prevent the heat generated by the self-heating of the object to be heated from being dissipated.

[0006] The microwave heating furnace for high temperature use is mainly composed of a microwave oscillating device, a waveguide which is a microwave oscillating port,
A fan to disperse the microwaves as evenly as possible,
It consists of a casing as a shield to prevent microwave leakage and a heat insulating material.

Conventional microwave heating furnaces for high temperature use as described in the above publication are small in size. Therefore, when the closed space (inside the furnace) that surrounds the object to be heated is constructed with the heat insulating material, it is possible to use a single heat insulating material in which the side wall and the ceiling portion are molded almost integrally. As a result, a support for supporting the heat insulating material was not particularly required. That is, the integrally molded single heat insulating material could be mechanically stable and self-supporting as it was.

However, when enlarging the furnace, a large closed space is required inside the furnace. In order to construct this large space, it was necessary to combine a plurality of heat insulating materials to form a wall or ceiling. As a result, it became necessary to support and fix a plurality of heat insulating materials.

On the other hand, in a conventional heating type large-scale furnace using a gas, electric resistance or the like as a heat source, the heat insulating material is fixed by using a rod-shaped or claw-shaped metal support as an outer frame. A general method is to fix the heat insulating member to a strong metal casing.

Further, the metal absorbs a part of the microwaves to generate heat, but has a property of reflecting most of the microwaves. This property is properly used as needed.
For example, in general electronic cookers and heating furnaces that use microwaves as a heat source, the property that microwaves are reflected by metal is used to enclose the entire cooker or furnace with metal so that microwaves do not leak outside the furnace. We are trying to prevent danger.

[0011]

In order to perform high temperature microwave heating, the following is required.

A) The object to be heated must be covered with a heat insulating material, and the microwave oscillator and the waveguide must be arranged outside the heat insulating material. That is, by using the heat insulating material, the heat generated from the object to be heated is confined inside the heat insulating material to keep the object to be heated at a high temperature, and the outside of the heat insulating material is kept to a low temperature, and is generated from the object to be heated. This is to prevent the microwave oscillator and the waveguide from being damaged by heat. Therefore, it is necessary to provide the object to be heated, the heat insulating material, the oscillator, and the waveguide in this order from the inside.

B) In the industrial world, there is a demand for a larger furnace at present, but it is difficult to integrally mold a large-sized heat insulating material in the molding stage as in the conventional case as the furnace becomes larger. . There is a demand for a structure in which a large number of small insulating materials that are divided or modularized are made to stand alone or stably supported and fixed.

C) On the other hand, microwaves are required to oscillate from an oscillator through a waveguide, pass through a heat insulating material, and efficiently reach an object to be heated. Therefore, it is necessary to avoid disposing a member that interferes with the waveguide and the object to be heated at least. Further, it is necessary to avoid arranging a member that loses its original function due to melting damage or the like. For example, metal plates, supports, etc. should not be placed as they are.

D) The heat insulating material needs to be a material that does not hinder the heat generation of the object to be heated by microwaves, that is, a material that has excellent microwave permeability.

E) In order to increase safety for the human body, it is necessary to prevent microwaves from leaking outside the furnace. That is, a metal casing that covers at least the outside of the heat insulating material and forms a closed space is required.

An object of the present invention is to use microwaves as a heat source,
An object of the present invention is to provide a high-temperature microwave heating furnace capable of high temperature and large size, and a support and a shelf member used for the same.

[0018]

To exemplify the solution of the present invention, there are a high temperature microwave heating furnace described in each claim and a support and a shelf used for the same.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is an improvement of a high temperature microwave heating furnace using microwaves as a heating source. An object to be heated, a heat insulating material, a support, and a metal casing are arranged in order from the inside. A waveguide is provided in a metal casing, a support and a shelf member are arranged, an object to be heated is arranged on the shelf member, and a heat insulating material is formed in the shape of a wall so as to surround the object to be heated. . The heat insulating material is supported by a support. The support and the shelf member are made of non-metallic and inorganic material.

The support must be safely located inside the waveguide. Therefore, the support is excellent in microwave permeability and heat resistance, has strength at high temperature, and is easy to mold and process. A non-metallic and inorganic material is selected as a material for the support and a member such as a shelf board that supports an object to be heated in the furnace.

Preferably, the support and the shelf member for the high temperature microwave heating furnace have the same dielectric loss as that of the object to be heated or smaller than that of the object to be heated. further,
The support and shelf member are one of materials such as alumina, mullite, steatite, zircon, cordierite, silica, quartz, silicon carbide, and silicon nitride.
It is preferably made of a refractory material consisting of a selection of one or more kinds.

As the material of the support for the heat insulating material in the present invention, a non-metallic and inorganic material which is excellent in microwave permeability and heat resistance, has strength at high temperature, and is easy to process is suitable. . Furthermore, considering the transmission, reflection, and absorption of microwaves, materials with excellent microwave transmission are
In other words, it has a property of hardly reflecting and absorbing microwaves. Dielectric loss is one of the factors that express the property. A material having a large dielectric loss easily absorbs microwaves, and as a result, the amount of heat generated by the material increases. Therefore, in a microwave heating furnace for high temperature, a material having a larger dielectric loss than the object to be heated is more likely to generate heat than the object to be heated, and thus becomes higher in temperature than the object to be heated, so that the required strength at high temperature cannot be obtained. It cannot be maintained and is easily deformed. That is, the maximum operating temperature of the furnace is lowered. Further, if such a support is near the object to be heated, it will be affected by heat from the support, making it difficult to accurately control the temperature of the object to be heated. Further, the microwaves are absorbed by the support before reaching the object to be heated, which deteriorates the heat generation efficiency of the object to be heated, which is not preferable. That is, in the microwave heating furnace for high temperature, the support that supports the heat insulating material and the shelf member that supports the object to be heated have the same dielectric loss as that of the object to be heated, or more than the object to be heated. It is preferably small. For example, when the object to be heated is mullite, the support and shelf members are preferably mullite or alumina, and when the object to be heated is alumina, the support and shelf members are alumina. It is preferable to make.

The support member and the shelf member may have any cross-sectional shape, cross-sectional width, diameter and the like. However, if the width and the diameter are too small, the strength as a support becomes insufficient, and if the width and the diameter are too large, the amount of microwaves absorbed by the support becomes large and the object to be heated cannot be efficiently heated. For the support and the shelf member, it is preferable to consider availability of materials, price, workability, and workability. The shape of the support is most preferably tubular, and the shape of the shelf member may be plate, cylindrical, prismatic, or the like.

With respect to the heat insulating member constituting the side wall, the support is passed from one side of the metal casing side surface located on the facing surface to the other side surface facing the other side so that the heat insulating material is supported by the support body. Further, the support is supported and fixed at a portion in contact with the metal casing. In this case, the support is preferably a long support capable of passing at least the distance between the side surfaces of the casing described above. At least a part of the long support may support the outside or surface of the heat insulating member. Also, the support may penetrate and support the heat insulating member.

Further, the plurality of heat insulating members can be integrated by penetrating with the support. In this case, the support may be short, and for example, a short support having a length such that at least adjacent heat insulating members can be supported and integrated is suitable. The length of the support can be determined according to the size and quantity of the heat insulating member to be integrated.

As the heat insulating material arranged on the ceiling portion, a structure in which the end portion of the arch made of the heat insulating material is supported by the upper end of the side wall heat insulating material made of the heat insulating material is suitable. The heat insulating members are joined together to form an arch structure, and both ends of the arch are supported by the upper end portions of the side wall heat insulating members constituted by the heat insulating members. In this case, the heat insulating material of the ceiling portion ( The furnace wall of the ceiling) can be configured.

Alternatively, the heat insulating material of the ceiling portion may be formed by penetrating the heat insulating member with a long supporting body and fixing the long supporting body with a metal casing instead of the arch structure.

Further, it is preferable that a space is provided between the outside of the side wall heat insulating material made of a heat insulating material and the waveguide, and the support is naturally cooled by natural convection of the air flow.

The heat insulating material is preferably assembled by combining a large number of heat insulating members on both the side wall and the ceiling. Various types of heat insulating members can be adopted.

[0030]

EXAMPLE A slurry in which alumina fibers, inorganic powder, and a binder are dispersed in water is prepared, and the slurry is vacuum-formed using a mold to form a board-shaped heat insulating member 1 having a thickness of 75 mm.
To get The heat insulating member 1 is laminated in the thickness direction of the heat insulating member, and the side wall heat insulating material is configured so that the laminating direction is parallel to the floor. An alumina tube 2 having an outer diameter of 35 mm was arranged as a support in the same direction as the stacking direction of the side wall heat insulating material so as to be in contact with the outer surface of the side wall heat insulating material, and the side wall heat insulating material was supported by these alumina tubes 2. .

The alumina tube 2 was passed from one side of the metal casing 3 to the other side surface that faces it. The end of the alumina tube 2 was inserted into a hole formed in the metal casing 3 and fixed. The metal casing 3 has six side walls except for the metal pedestal 4, and the heat insulating material 1 on the side wall.
And, the heat insulating material 1 in the ceiling portion is arranged so as to surround it.

As the heat insulating material 1 for the ceiling portion, a board-shaped heat insulating member 1 is used which is lapped after processing and laminated in the thickness direction of the heat insulating member 1, and the direction is parallel to the floor. Thus, the heat insulating material 1 for the ceiling portion was constructed.
At this time, both ends of the arch-shaped ceiling portion are supported by the upper ends of the sidewall heat insulating materials 1. The closed space (inside the furnace) surrounded by the heat insulating material 1 has a width of 1140 mm and a length of 1140 m.
m, effective height was 375 mm.

In the floor of the furnace, the board-shaped heat insulating member 1 and the alumina refractory 5 are laid on the metal pedestal 4, and the metal pedestal 4 is used.
Has a structure that moves up and down. A conventional structure can be used for this lifting structure. Further, a space of about 200 mm is provided between the side wall heat insulating material 1 and the ceiling heat insulating material 1 and the metal casing 3 so that the structure can be cooled by natural convection of the air flow.

Inside the furnace, a shelf plate member 10 in the form of an alumina plate of 3 × 200 × 200 mm, an outer diameter of 35 mm and a height of 50 m is used.
m of the alumina tube-shaped shelf board members 11 were used in combination, and configured and arranged as shelf board members.

When the ceramic material as the object to be heated was heated at 1300 ° C. in the microwave heating furnace of the illustrated example, the ceramic material could be heated without distortion or cracking. Also,
The support was able to securely support and secure the insulation. The shelf member could stably support the object to be heated.

[0036]

According to the present invention, since a support made of a non-metallic and inorganic material is used, the support has excellent microwave permeability and heat resistance, strength at high temperature, and easy processing. is there.

In a high temperature microwave heating furnace, if such a support is arranged inside the waveguide, and a plurality of heat insulating members are combined and supported by the support, the heat insulating material is safely supported, It can be fixed and the microwave heating furnace for high temperature can be easily enlarged.

Further, according to the present invention, since the shelf member made of a non-metallic and inorganic material is used, it has excellent microwave permeability and heat resistance, has high strength at high temperature, and is easy to process.

In the microwave heating furnace for high temperature, by arranging and using such a shelf member in the furnace, it is possible to stably support the object to be heated.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a high temperature microwave heating furnace according to the present invention.

[Explanation of symbols]

1 Heat insulation material (heat insulation member) 2 Alumina tube 3 metal casing 4 metal pedestal 5 Alumina refractories 6 Heated object 7 Microwave oscillator 8 Waveguide 9 High temperature microwave heating furnace 10 Alumina plate-shaped shelf board member 11 Alumina tube-shaped shelf board member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masato Osawa             4-4 Nihonbashi Hisamatsucho, Chuo-ku, Tokyo Itoshige             Building Toshiba Monoflux Co., Ltd. (72) Inventor Yasuo Misu             4-4 Nihonbashi Hisamatsucho, Chuo-ku, Tokyo Itoshige             Building Toshiba Monoflux Co., Ltd. F term (reference) 3K090 AA03 AB07 AB09 BB01 EA02                       EA09 PA00                 4K055 NA05                 4K063 AA06 AA09 CA06 FA82

Claims (3)

[Claims] 1. A high-temperature microwave heating furnace using microwaves as a heating source, wherein an object to be heated is
The heat insulating material, the support, and the metal casing are arranged, the waveguide is provided in the metal casing, the support and the shelf plate member are arranged, the object to be heated is arranged on the shelf plate member, and the object to be heated is arranged. A high-temperature microwave heating furnace characterized in that a heat insulating member is arranged so as to surround the heat insulating member, and the heat insulating material is supported by a support, and the support and the shelf member are made of a non-metallic and inorganic material. 2. A support and a shelf board member used in a high-temperature microwave heating furnace using microwaves as a heating source, characterized in that the dielectric loss is the same as or smaller than that of the object to be heated. High temperature microwave heating furnace support and shelf member. 3. A support and shelf board member used in a high-temperature microwave heating furnace using microwaves as a heating source, comprising alumina, mullite, steatite, zircon, cordierite, silica, The support for a high-temperature microwave heating furnace and a shelf board member according to claim 2, which are made of a refractory material made of one or more kinds of quartz, silicon carbide, and silicon nitride.