JPH04160060A - Burning method for molded carbon body - Google Patents

Abstract

PURPOSE:To form the uniform temp. distribution in a furnace at good thermal efficiency and to perform burning of a molded carbon body by loading a molded green carbon body into a saggar fitted with a cover in a state wherein the molded green carbon body is buried in a carbonaceous packing, burning and treating this saggar in a specified mode. CONSTITUTION:Firstly a molded green carbon body 1 is loaded to the inside of a saggar 3 in a state wherein this molded green carbon body is buried in a carbonaceous packing 2 good in thermal conductivity such as coke or graphite powder. A platelike cover 4 described below is placed on the top face of the carbonaceous packing material 2 filled in the saggar 3. The platelike cover 4 is made of the same iron-based material as the saggar material and has diameter slightly smaller than the inside diameter of the saggar. Furthermore, a weight member 9 made of carbon material or ceramics material is placed on the upper part thereof. The upper end is covered with a covering cover 10. The saggar 3 constituted as shown in the method is set to the inside of the compartment 6 of a burning furnace via the bricks 12 on the bottom part of an aperture. Loading work of the furnace is completed. Since burning treatment is performed in this state wherein the furnace is loaded, burning of the molded green carbon bodies 1 is advanced while the passed combustion flame is brought into contact with the whole outside circumferential face of the saggar 3 along the directions shown in arrows.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention... The present invention relates to a method for firing and carbonizing a raw carbon compact, and in particular to an improvement in a furnace filling means in the firing process.

[Conventional technology]

Generally, in the firing process for carbon materials, the carbonized carbon molded body to be treated is set in a mass in a single firing furnace or a continuous firing furnace (reed hammer), and the surrounding area functions to prevent oxidation, uniform heating, and deformation of the molded body. A method is adopted in which the brick is encapsulated with a packing material such as coke powder or silica sand and heated indirectly from outside the brick wall using a combustion flame. In this case, when firing a normal carbonized carbon material, the packing material is filled so as to be in direct contact with the molded body, but when targeting an isotropic carbon material that particularly dislikes oxidation phenomena, a second packing material is used.
As shown in the figure, a carbonized molded body l is produced using a rubber press.
A furnace filling method is adopted in which the sagger 3 is loaded with the sagger buried in the carbonaceous packing 2, a plate-shaped lid 4 is placed on the top surface of the sagger 3, the plate lid 4 is placed on the top surface, the sagger is set in the firing furnace section, and the surrounding area is covered with a packing material 5. (For example, Japanese Patent Publication No. 1-58126).

[Problem to be solved by the invention]

However, in the case of the conventional sintering method, the packing material 5 is also present around the sagger 3. Heating of the green carbon compact 1 proceeds through extremely indirect heat transfer by the combustion flame flowing through the outer peripheral space formed by the furnace wall bricks. Therefore, there are disadvantages in that the thermal efficiency is poor and the temperature distribution tends to be uneven.

In addition, the presence of the banking material 5 requires time and effort for the dry pile work, is uneconomical in terms of energy since excess packing other than the product must be heated, and delays furnace cooling after firing. Give questions such as.

The purpose of the present invention is to maintain a uniform temperature in the furnace with good thermal efficiency by bringing the combustion flame into direct contact with the outer surface of the sagger without filling the area around the sagger that causes the various problems mentioned above. It is an object of the present invention to provide a firing method for forming a carbon material with excellent properties while saving energy, resources, and labor.

[Means to solve the problem]

In order to achieve the above object, the method for firing a carbon molded body according to the present invention involves loading a sagger with a lid with the raw carbon molded body buried in carbonaceous packing, and firing the sagger through an open bottom brick. The structural feature is that the firing process is performed while the combustion flame set in the furnace section and circulating is in contact with the entire outer peripheral surface of the sagger.

The firing method of the present invention can be applied to carbon molded bodies made by any molding method, including extrusion molding, molding, and rubber press molding, but is particularly applicable to rubber press molded bodies where oxidation during the firing stage is a problem. It is highly effective in some cases.

Hereinafter, the present invention will be explained in detail based on FIG. Note that the same members as in FIG. 2 are given the same reference numerals.

FIG. 1 is a side sectional view of a reed hammer furnace illustrating a packed state applied to the firing method of the present invention, in which 6 is a firing furnace section partitioned by a cassette brick wall 7, and 8 is a furnace lid.

In the firing method according to the present invention, first, a green carbon compact 1 is embedded in a carbonaceous packing 2 having good heat conductivity such as coke or graphite powder, and then loaded into a sagger 3. The sagger 3 is usually made of an iron-based material (preferably stainless steel) as a square or cylindrical bottomed container. The number of green carbon molded bodies 1 to be loaded is determined by the volume of the sagger 3 and the size and shape of the processed molded bodies.

On the upper surface of the carbonaceous packing material 2 filled in the sagger 3, a plate-shaped lid 4 made of the same iron-based material as the sagger material and having a diameter slightly smaller than the sagger inner diameter is placed, and a carbon material is further placed on top of the plate lid 4. Or a weight member 9 made of ceramic material
, and the upper end is covered with a cover lO.

This structure is intended to prevent air from entering from the top of the sagger 3, but in order to make the effect even more complete, a carbonaceous fine packing material with fine particle size is placed on the top surface of the plate-like lid 4. 11 is preferably filled.

The plate-shaped lid 4, the weight member 9 and the fine packing material 11
This method is effective when dealing with a rubber press molded product, and in the case of a raw carbon molded product made by extrusion molding or molding, the lid is placed directly on the top surface of the carbonaceous packing material 2 filled in the sagger 3. 10 (a gas vent hole may be provided on the lid surface) may be placed.

The sagger 3 configured as described above is set inside the kiln section 6 via the open bottom brick 12, and the kiln filling work is completed.

Since the sintering process is carried out in this furnace packed state, the sintering of the green carbon molded body 1 progresses while the circulating combustion flame contacts the entire outer peripheral surface of the sagger 3 along the arrow.

[For production]

According to the firing method of the present invention, as described above, the firing frame directly contacts the entire outer peripheral surface of the sagger. For this reason,
The sagger is heated from the entire surface with extremely high thermal efficiency, and the raw carbon molded body receives heat evenly without any positional fluctuations in temperature due to the heat transfer effect of the filled carbonaceous packing.

At the same time, the intrusion of oxidizing gas into the interior of the sagger is prevented by the partitioning effect of the plate-like lid, fine packing material, cover lid, etc. interposed above the sagger.

This action makes it possible to efficiently process a raw carbon compact into a fired body with a normal structure, and there is always little variation in the physical properties of the material, preventing the occurrence of firing cracks even in large, high-density materials. effectively prevented.

〔Example〕

Examples of the present invention and comparative examples are shown below. Although the example shows an example in which an isotropic carbon molded body is fired using a rubber press, the target raw carbon molded body is not limited to this.

Example 70% by weight of fine coke powder and 40% by weight of tar pitch were kneaded in a kneading machine, cooled, and the finely pulverized molding raw material was rubber press molded to produce an isotropic raw carbon molded body.

Five pieces of this raw carbon molded body were loaded into a tea cylinder-shaped iron sagger having a diameter of 1100 ss+ and a height of 9000 mm at equal intervals and embedded in graphite grain packing. As shown in FIG. 1, an iron plate-shaped lid and a weight member made of carbon material were placed on the top surface of the sagger, with gaps filled with graphite fine packing material, and the upper end was covered with a cover.

The sagger described above was set on an open bottom brick in the compartment of a lead hammer furnace.

In this state, the combustion source was ignited, and the combustion flame was brought into direct contact with the entire outer circumferential surface of the sagger along the direction of the arrow in FIG. 1, and the temperature was raised to 1000° C. to perform the firing process.

In this case, the temperature change (relationship between time and temperature) during the heating stage was measured at the top of the sagger ■, the center of the sagger (position corresponding to 172 of the sagger length) ■, and the bottom of the sagger ■ This is shown in FIG. 3 in comparison with the flame temperature ■. Each of the temperature rise curves ■ to ■ in Figure 3 showed almost the same behavior without variation while trending slightly higher than the flame temperature ■, and it was confirmed that there was an even temperature distribution with no fluctuation depending on the sagger position. .

In addition, with improved thermal efficiency, the amount of heavy oil used is reduced from 400ffi/ton to 300! compared to a regular lead hammer furnace! /
It was found that the amount could be reduced to about 75%.

The isotropic carbon material discharged from the furnace after firing had no evidence of oxidation inside its structure, and no defects such as cracks or breakage were observed.

Comparative Example The same isotropic carbon molded body as in the example was subjected to firing treatment with the outer periphery of the sagger filled with coke powder packing material using the furnace packing structure (two sagos packed) shown in Fig. 2. .

° In this case, the temperature change during the heating stage is calculated as follows: the top of the sagger, the center (bottom of the upper sagger)
Measurements were taken at each position (2) and the lowest part of the sagger (the lowest part of the lower sagger), and the results are shown in FIG. 4 in comparison with the flame temperature (2).

From the results in Figure 4, each temperature rise curve ■~■ is the frame temperature■
It is found that the temperature difference is distributed at a lower position, and the temperature distribution fluctuates more widely than in the example.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to efficiently perform the firing treatment of a green carbon molded body under uniform temperature distribution, and it is particularly effective when firing a high-density isotropic carbon molded body. Demonstrate the power of In addition, since the process of filling the outside of the sagger with banking material, which was done in conventional technology, is omitted, energy saving is achieved by improving the thermal efficiency of the entire firing process, resource saving is achieved by eliminating the need for packing material, and packing material This brings about labor-saving effects, such as eliminating hot work such as dry mountain drying.

[Brief explanation of drawings]

FIG. 1 is a side sectional view illustrating a packed state of a firing furnace applied to the present invention, and FIG. 2 is a side sectional view showing a packed structure of a firing furnace according to the prior art. FIG. 3 is a graph showing a temperature rise curve in an example of the present invention, and FIG. 4 is a graph showing a temperature rise curve in a comparative example. 1... Raw carbon molded body 2... Carbonaceous packing 3... Sagger 4... Plate lid 5... Packing material 6... Kiln section 7... Cassette brick wall 8...・Heart 9... Weight member l
O...Cover lid ll...Fine packing material 12...
・Opening bottom brick Applicant: Tokai Carbon Co., Ltd. Representative Patent Attorney: Masaya Takahata Figure 1

Claims (1)

[Claims] 1. The raw carbon molded body is loaded into a sagger with a lid while being embedded in the carbonaceous packing, and the sagger is set in the firing furnace section through the open bottom brick, so that the circulating combustion flame is brought into contact with the entire outer peripheral surface of the sagger. A method for firing a carbon molded body, characterized in that a firing treatment is performed during the firing process.