JP3086677B2 - Furnace for ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace for ceramics, and more particularly to a furnace for ceramics having a structure suitable for firing ceramics and protecting against erosion by erosive gas and erosive inorganic substances generated during firing of ceramics and the like.

[0002]

2. Description of the Related Art Among furnaces for the ceramic industry, an electric furnace uses an electric heating element as a heat source. Usually, the heating element is exposed in the heating space, or the heating element is supported in a magnetic tube. The firing of the porcelain may be at a high temperature, in a reducing atmosphere, may generate solid dust such as ash, or may take a long time. In addition, the heated space, that is, the structure in which the required volume of the fired material is secured is secured. Even in such a case, the space to be heated and the heating space have conventionally been in a communicating state.

[0003]

Taking Bizen firing as an example of firing ceramics, a reducing atmosphere is used during firing, and an organic material such as straw for forming a reducing atmosphere or forming a pattern on the skin is used. The decomposition product emits the erosive inorganic substance and the erosive gas into the heated space. Therefore, even if the heating element is supported in the porcelain tube, its surface is contaminated or eroded. The same applies to a furnace of a type in which a heating element is covered with a tubular element as shown in JP-B-55-1513. When the fired body passes through a small heating space as in the case of producing carbon fibers (for example, Japanese Patent Application Laid-Open No. 57-157988).
In Japanese Patent Application Laid-Open No. 8-121969), even if an erosive gas is generated, the fired body can be prevented from being eroded by isolating the fired body by a tubular partition. However, ceramic furnaces require large volumes of fired material, and for high-temperature firing such as Bizen firing, which must be fired at 1200 ° C or higher using a heating element, the heating element must be separated by a tubular partition. However, heat is trapped in the tube and causes damage, which is not preferable. Conversely, when the heating element is exposed,
There is also pollution erosion due to the scattering of ash (ash). Therefore, it has been difficult to protect the electric heating means (heating element).

[0004] Commonly used chemical erosion substances in ceramic furnaces include glaze used for decorating and coloring the surface of a fired ceramic body, and alkali oxides which are ash components of plants and plants used as a base for the glaze.
Substances mainly composed of alkaline earth oxides, low melting point metal oxides, and metal oxides of surface oxide films generated by heat treatment of metals are known. In addition, corrosive gas (nitrogen oxide, sulfur oxide, halogen-based gas) contained in the heat source gas required for heating is also a cause of erosion and deterioration of the heat insulating material and the heating element in the furnace at a high temperature. For this reason, the disconnection caused by the erosion due to the contact reaction with the erodible inorganic substance scattered is not caused by the repeated pattern of the evaporation of the heating material and the generation and peeling of the surface protective film, which are the original consumption mechanisms of the heating element. It is a major factor in life. The present inventor seeks to solve these difficulties.

[0005]

As a result of examining the above-mentioned problems, it has been found that a highly heat-conductive ceramic molded body is disposed as a partition between a heated space and a heated space of an electric furnace, and that a fired body such as a ceramic is fired. In addition, the heating element is isolated from erosive inorganic substances and erosive gases in glazes and organic decomposition products .

[0006] A partition wall material referred to here, charcoal of siliceous ceramic
Click, using any of the high thermal conductivity ceramic body nitrided silicon-bonded silicon carbide ceramic, a plate-like member, the thickness 1 to 50 mm, and it is preferably a 2 to 20 mm. When the thickness is 1 mm or less, it is difficult to manufacture and easily broken. Also,
If it is 50 mm or more, it is expensive and thermal loss occurs.

As a more specific structure, the space to be heated is formed of a plurality of flat partition walls made of a high thermal conductive ceramic molded body so that the horizontal cross section is polygonal, and a gap between adjacent partition walls is sealed. In addition, a ceramic furnace was obtained in which adjacent partition members at a predetermined angle were supported by supports from the furnace outer wall side (heating space side). Although it is a furnace for the ceramic industry, it can also be used for firing other objects to be fired.

[0008]

1 to 3 show an embodiment of a ceramic furnace according to the present invention. FIG. 1 is a longitudinal sectional view, and FIG.
A sectional view and FIG. 3 are perspective views of a partition wall support. Figure 1,
As shown in FIG. 2, a heating space 3 is formed by circulating a heating element 3 along a wall surface in a baking chamber 2 formed in a rectangular shape inside an insulated furnace wall 1 formed by using a refractory brick or the like. The inside is a heated space 5 for firing ceramics and the like. The heating element 3 is in the form of a coil made of a wire of iron-chromium-aluminum alloy in this example. Partition support members 6 shown in FIG. 3 are used in the four corners of the firing chamber 2 in the vertical direction. The partition wall support 6 is formed by partitioning one corner of a prism into a square shape to form a partition wall support 6a. Further, a heating element support tube insertion hole 6b is provided in a direction perpendicular to the direction. With such a structure, four high thermal conductive ceramic molded bodies (in this example, 10 mm thick) can be arranged as the partition wall member 7 between the heated space and the heated space by the partition wall support member 6. In addition, the heating element supporting tube 8 having the heating element 3 can be supported. Heating element 3
Is supported outside the support tube in the case of firing at a high temperature, and is supported inside the support tube otherwise. At the bottom of the furnace is a porcelain tube 9 for gas introduction.
A rectangular bottom partition wall material 11 having a gas introduction hole 10 to which is connected is supported by a support column 12. The canopy 13 is provided with a gas discharge hole 13a and is formed of ceramic fiber.

While burning the pine wood 15 and the like along the way into the gas introducing porcelain tube 9 by the gas burner 14, the combustion gas is sent together with the combustion ash, and at the same time, the heat from the heating element 3 is applied to the fired body 16. High thermal conductive ceramic molded body for partition material 7
(In this example, silicon carbide (SiC) ceramic, 15mm thickness)
Is used, heat is efficiently conducted from the heating element 3, and the heating element 3 can be isolated from corrosive inorganic substances and corrosive gas during firing of the ceramic. The airtightness of the heated space 5 is increased by sealing with the vertically long partition wall support 6.

FIGS. 4 and 5 show another embodiment in which the baking chamber 2 has a rectangular cross section with a horizontal cross section. FIG. 4 is a cross sectional view corresponding to FIG. 2, and FIG. FIG. The feature of this example is that in order to form a heated space 5 having a rectangular cross section using four partition members 7, a partition member supporting member 17 having a 90 ° outer angle and a vertically long horizontal cross section and having a vertical section is provided.
Are used at the four corners, and auxiliary support pieces 18a, 18b, 18c, each of which is cut off at one corner of the square, are arranged at the upper, middle, and lower portions between the heat insulating furnace wall 1 and fixed. In order to facilitate assembling and increase the adhesiveness, the abutting portions on both sides in the vertical direction of the partition wall member 7 are formed obliquely. The hermeticity is increased by sealing with the vertically long partition wall support 17. The heating element 3 is provided between the heat insulating furnace wall 1 and the partition wall support 17. Partition material 7
Is a SiC material (a plate material having a thickness of 20 mm).

FIG. 6 is a perspective view of an essential part showing how the partition wall member 7 is supported when the space to be heated has a more polygonal horizontal section than in the previous examples. A plurality of high thermal conductive ceramic molded bodies are formed of a flat SiN-SiC partition wall material 7 to seal the gap between adjacent partition walls, and to separate adjacent partition walls at a predetermined angle to the furnace outer wall side ( The heating space side) is supported by the partition wall support 17. Also in this example, the airtightness is increased by sealing with the vertically long partition wall material support 17.

[0012]

According to the present invention, the erosion and deterioration of the heat insulating material in the furnace and the heating element in the furnace for the ceramic industry are prevented, and the disconnection due to the contact reaction with the erodible inorganic substance scattered is prevented, thereby shortening the life of the heating element. And a structure with good conduction efficiency even with indirect heating.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a ceramic furnace according to the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a perspective view of a partition wall support.

FIG. 4 is a sectional view corresponding to FIG. 2 of another embodiment.

FIG. 5 is a perspective view showing a state where a partition member is assembled.

FIG. 6 is a perspective view of an essential part showing how the partition wall material is supported in the case of a polygon.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated furnace wall 2 Firing room 3 Heating element 4 Heating space 5 Heated space 6 Partition material support 6a Partition material support 6b Heating element support tube insertion hole 7 Partition material 8 Heating element support tube 9 Magnetic tube for gas introduction 10 Gas inlet hole 11 Bottom partition wall material 12 Supporting column 13 Canopy 14 Gas burner 15 Matsu split wood 16 Fired body 17 Partition wall support 18a, 18b, 18c Auxiliary support piece

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-221764 (JP, A) JP-A-10-141859 (JP, A) JP-A-4-320789 (JP, A) 6740 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F27B 5/00-5/18 F27D 5/00 C04B 33/32

Claims (1)

(57) [Claims] 1. Between the heated space and the heating space of the electric furnace
Silicon carbide ceramic, silicon nitride bonded silicon carbide ceramic
One of the high thermal conductive ceramic molded products
For high thermal conductivity ceramics with a thickness of 1 to 50 mm.
The horizontal section of the space to be heated is polygonal
And seal the gap between adjacent partition walls.
First, the adjacent partition wall material is set at a predetermined angle on the furnace outer wall side.
(Heating space side) A furnace for ceramics, which is supported by a support tool and isolates the heating element from erosive inorganic substances and erosive gases in glazes and organic decomposition products during firing of ceramics and other fired bodies .