JPS5926236Y2 - Furnace wall structure of carbonaceous product firing furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention is a method for firing or calcining carbonaceous products such as electrodes for arc furnaces, electrodes for aluminum electrolytic furnaces, and electrode plates (herein, calcining is also referred to as firing).

) is related to the furnace wall structure of the furnace.

Generally, these carbonaceous products are molded using pitch tar etc. as a binding material and used as a product after being calcined or fired at about 800 to 1400℃, and some are used after being heat-treated in a graphitization furnace after firing. There are things that are done.

When firing these products, in order to prevent the products from deforming or oxidizing during firing, the products are generally stuffed into the furnace with a filler mainly made of coke powder, and side walls, intermediate walls, etc. The product to be fired is heated by combustion gas through the brick walls from the top and bottom, and the volatile components contained in tar and pitch are burned off and carbonized.

For this firing, a large furnace called a single furnace, a spherical furnace, or a ring kiln is generally used, and typical examples include a lead hammer furnace, a Pescinet type furnace, and an Alcan type furnace.

The side walls, intermediate walls, etc. of these firing furnaces are constructed with cavities so that combustion gas can pass through them and heat the objects to be fired.This structure is constructed using small bricks that form cavities. Alternatively, furnace construction work is carried out by combining small block bricks with small cavities, but dozens of blocks are required to construct just one intermediate wall or side wall, and the construction is difficult. Furnace work was extremely complicated and required a great deal of labor.

In addition, the volatile components evaporated from the carbonaceous product to be fired, for example in the case of a Pecinet furnace, are evaporated from the top surface, or are passed through the joints between each brick into the combustion gas flow path and extracted together with the firing gas. was beginning to appear, but this withdrawal was not sufficient.

The present invention was discovered as a result of various studies to solve these problems.Firstly, it provides a furnace wall that facilitates the removal of volatile components, and secondly, it provides a furnace wall that facilitates the removal of volatile components. In addition, we have succeeded in providing a furnace wall that significantly simplifies the furnace construction work by using a small number of large blocks instead of dozens of small block bricks.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory longitudinal cross-sectional view showing a typical firing furnace consisting of a carbonization chamber, which is a firing chamber for carbonaceous products, and a combustion chamber having a combustion gas passage.

In the drawings, reference numeral 1 denotes a firing chamber, and a carbonaceous product 2, which is an object to be fired, is placed in a chamber filled with coke powder 3.

Here, the firing chamber is divided and formed by a side wall 4 and an intermediate wall 5, and if there is only one combustion chamber, the intermediate wall is not necessarily necessary, and when a large number of firing chambers are provided, the number of intermediate walls increases accordingly. become.

In these firing furnaces, the conventional side walls 4 and intermediate walls 5 are
As mentioned above, small blocks (e.g. 460 x 145
The combustion gas passage 7 was constructed using a large number of bricks 6, for example, usually 2,400 bricks (220 mm, etc.).

The combustion gas flows through the gas passage formed in this way in the general direction of the arrows A-+B, and the heat is applied to the firing chamber through the fireproof walls such as the side walls and the intermediate wall, thereby heating the product.

At this time, volatile components from the carbonaceous product to be fired enter the gas passage 7 through the upper surface of the furnace and the numerous joints 21 formed by the phosphorus tiles 6, which are small blocks, and are removed by the combustion gas. carried to.

In contrast, the present invention does not remove volatile components from the joints, but instead provides a large number of ventilation holes in the refractory block itself that makes up the furnace wall, and guides the volatile components into the gas flow path through these ventilation holes. As a result, there was no problem in reducing the number of joints by constructing the furnace wall with large blocks.

In this way, the present invention allows the use of large refractory blocks, and considering the ease of furnace construction work that can be achieved by using large blocks, the advantages of using large refractory blocks are significant. The present invention will be explained by taking as an example a furnace wall using large blocks, but of course, forming vent holes is also effective when constructing a furnace wall using conventional bricks, which are a large number of small blocks.

FIG. 2 is a sectional view showing a firing furnace according to the present invention, in which one side wall 4 and middle wall 5 are constructed of several large refractory blocks 8.

The large refractory block 8 preferably has at least one cavity 9 that serves as the combustion gas passage 7 .

Here, the typical example of the large block illustrated in FIG.
This will be explained with reference to the figures.

The large block 8 constituting the furnace wall of the present invention has a large number of ventilation holes 24 in the side walls 22 and 23 facing the side 10 forming the firing chamber 1 in the thickness direction, that is, in the direction leading to the firing chamber. .

This ventilation hole 24 only needs to penetrate the side wall of the block, and the drawing shows an example as a long and narrow hole,
The shape is not limited to pores, but can be any shape such as circular, rectangular, or square.

In addition, in a preferable block, the ventilation hole is a small hole, and the hole is provided so that the longitudinal direction of the hole is located in the vertical direction when the block is constructed.

Here, the shape may be any shape, but on the other hand, if the size of the opening of the hole itself, that is, the width of the ventilation hole, is too large, the coke powder that fills the inside of the firing chamber will come out. It is best to keep the width as small as possible, usually 10 mm or less, preferably about 5 mm or less.

The number of these ventilation holes can be determined depending on the purpose, but as mentioned above, the width of the holes is small, so a plurality of long pores are required, and they are usually distributed over the entire side wall. Even long pores require three or more, and short pores or small pores usually require several dozen to ten-odd pores.

In the present invention, it is preferable to provide this ventilation hole in the refractory block that constitutes all or most of the intermediate wall and/or side wall that constructs the furnace wall, but of course, even if it is only partially provided, it will not have a certain effect. Depending on the furnace, various forms can be taken.

For example, in the fireproof block constituting the intermediate wall, it is effective to have ventilation holes in both side walls 22 and 23.

Here, the use of the block provided with the ventilation holes of the present invention is preferable in the case of a large block as described above, and the use of the large block will be further explained below.

The large refractory block (hereinafter referred to as large block) 8 in FIG. 3 preferably has at least one cavity 9,
The contact surface area 10 facing the firing chamber with the firing chamber (hereinafter referred to as firing base area) is at least 3600 cm2, and the simplest shape is shown in FIG.

The one in FIG. 3 is, for example, a: 1305.6. b
: 900. C: 500. The wall thickness is 100 mm (all units are mm), and the firing surface area is approximately 12550 cm.
It has one cavity, and the area of contact with the combustion gas (hereinafter referred to as gas contact area) of this cavity is approximately 27,700 cm2.

By using such large blocks, up to now approximately 2
The wall, which used to be constructed with 500 foreground bricks, was replaced with just 1 brick.
It can now be constructed with two pieces, the furnace construction work itself using a crane is simplified, and the time required for furnace construction has been reduced from the previous hours.
It was possible to shorten the time to less than 40 hours (for example, 40 hours to 3 hours).

Such simplification of furnace construction work has little effect unless the firing surface area of the large block is at least 3,600 cm2, and is more effective when it is desirably 10,000 cm2 or more.

Furthermore, if it is too large, manufacturing work will not be easy.
In addition, problems such as making it difficult to transport and requiring labor to construct the furnace occur, so it is unavoidable to limit the size to a maximum of about 40,000 cm2.

One of the advantages of this invention is that it is possible to form a large gas flow passage inside with just one block due to the use of such a large block, which not only facilitates the furnace construction work but also greatly reduces the It is possible to improve the durability of the block and improve the firing efficiency.

Considering these points, the gas contact surface area of one cavity is preferably 10,000 cm2 or more; on the other hand, if it is too large, the strength of the structure will decrease and the block will be easily damaged during transportation or furnace construction. .

This is undesirable because it is easily broken by mechanical shock when the material to be fired is taken in and taken out, so the upper limit is limited to about 30,000 c♂.

Also, in one large block, the number of cavities is usually 1.
In view of the above-mentioned advantage of increasing the gas contact area in one cavity, it is desirable that the number be two, or as in many of the examples described later, the purpose can be sufficiently achieved. However, if the large block is very large or if the block is thin despite the large area of the block that comes into contact with the object to be fired, it is advantageous to have a large number of cavities in terms of the strength of the structure. In some cases, it may be advantageous to have a large number of cavities so that the combustion gas uniformly heats the wall surface.

For example, in a firing chamber having an area of 12,000 cm 2 or more, it is effective to provide 2 to 6 chambers.

In any case, it is neither necessary nor desirable to provide ten or more cavities in one large block.

Next, some of the fireproof blocks constituting the present invention will be explained with reference to FIGS. 4 to 8.

The one shown in FIG. 4 has two convex protrusions 1 on the upper end surface 11.
2, in which a concave part 14 was formed on the lower end surface 13 to fit with the protrusion of an adjacent block when constructed, and more than ten pores 24 were formed in two stages in the side wall 22, 23. It is something.

The one shown in FIG. 5 has two cavities 9 and has an upper end surface 11.
Two protrusions 12 are provided on the surface, and two concave grooves 14 are provided on the lower end surface.
In addition, one row of concave portions 15 are formed on both sides, and several fine ventilation holes 24 are formed in the vertical direction on the side walls 22 and 23.

The one shown in FIG. 6 has a protrusion 12 and a groove 14 formed on each of the two hollow parts and the upper and lower end surfaces, and a corresponding groove and protrusion are formed on the other side. In this case, a large number of point-shaped ventilation holes 24 are formed in the side walls 22 and 23.

The one shown in FIG. 7 has six cavities 9, a longitudinal protrusion 12 on the upper end surface, a transverse protrusion 17, a groove 14 on the lower end surface, a recess 15 on one side, and a protrusion on the other side. Each of the strips 16 is provided with a large number of fine ventilation holes 24 formed in the side walls 22 and 23 in the vertical direction.

FIG. 8 shows an example of a block located at the lower part of the side wall or intermediate wall of the firing furnace, in which a combustion gas inlet/outlet 18 is formed at the lower side of the side.

In these examples, the protrusions and grooves on the upper and lower end surfaces are
When constructing blocks, the ease of fitting makes positioning, fixing, etc. easier, which is more important when using large blocks, and is more useful for improving work efficiency.

In addition, when forming a space between adjacent blocks, the recessed part and/or the protruding part on the side surface can have the effect of making the wall surface an integral structure by filling the space with castable or ramming material. Similar effects can be obtained when the same construction as the above-mentioned fitting at the upper and lower end surfaces is used.

In the present invention, the firing furnace is one in which the walls and/or side walls are preferably constructed of large blocks.
Of course, in a furnace provided with an intermediate wall, it is desirable to construct the entire or most part of the wall along with the side walls by using the large block, and it is also natural to use other small and medium blocks in part. It will be done.

The configuration of the present invention is as described above, but in order to make the present invention more effective,
On the one hand, it is necessary to have a fire-resistant molded body with large blocks and high strength, but the inventors of the present invention have conducted research on various desirable products in this regard, and it can be said that this result has made the present invention more effective. .

The large refractory blocks that make the present invention possible can be obtained in several ways, and the inventors' method will be described below.

In other words, the large refractory block that makes this invention possible contains alumina cement in a total amount of 1 to 5% by weight with the refractory material, and contains ultrafine powder with a particle size of 1μ or less in the refractory material. is 1 to 1 in the total amount of fireproof material and alumina cement
A precast unfired product is produced by kneading a refractory composition with a proportion of 7% with a small amount of water to form a refractory composition, and placing this mixture in a predetermined mold and molding it. be.

According to this method, large-sized precast blocks can be obtained, and these have high strength due to the combination of a small amount of alumina cement and ultrafine powder.

First, as fireproof aggregate, it is best to use hard and dense materials that are as fire-resistant and corrosion-resistant as possible, but a variety of materials can be used.
Suitable materials include silica sand, alumina (electrofused or sintered), and calcined clay (bauxite, etc.).

The particle size of this aggregate does not need to be extremely strict and may be within the range used as ordinary aggregate, for example 15~Q, Q
About 1 mm is sufficient.

Next, calcium aluminate is combined with 1 to 5% of alumina cement, which is the main component, to form a fireproof composition. Due to this, we were able to successfully reduce the amount to an extremely small amount, making it possible to achieve effects that cannot be achieved with conventional castables.

In other words, although it has been considered and partially implemented to construct this type of block using castable materials that are easy to construct, the characteristics of alumina cement bonding have traditionally made it difficult to use alumina cement. Since it requires a large amount of water (15 to 30%), there are many pores (about 30%), and there are disadvantages such as a decrease in strength at 500 to 100 °C before ceramic bond formation. There were restrictions on its use, and it was difficult to use it, especially as a large precast product.

This invention uses extremely little alumina cement,
Through the use of a small amount of water and the action of activated fine powder, the porosity is reduced to 10% or less, and strength is developed, and the alumina cement has excellent hot properties and no strength loss at intermediate temperatures. It has been found that if the amount exceeds 10% of the total amount with the refractory material, this effect will not be sufficiently exhibited, and if the amount is less than 1%, a high-strength product cannot be obtained, which is not preferable.

In addition, the necessity of ultrafine powder in refractory materials means that it is possible to bring remarkable strength and density to refractory structures even with a very small amount of alumina cement, which is especially necessary for firing furnace walls. This is because it is possible to produce a product with no reduction in hot properties, intermediate strength, or product strength.

These characteristics are not desirable if the amount of ultrafine powder is too small, and if it is too large, the filling properties of the molded product will be poor, that is, the compactness will be impaired.

Here, this ultrafine powder has a composition of A1□03. Cr2O
Metal oxides such as 3° ZrO2, TiO2, SiO2, etc., or those having the main component can be preferably used.

In this way, a refractory composition consisting of a predetermined refractory material and a predetermined amount of alumina cement is kneaded with a small amount of water to form a mixture for obtaining a precast product. Generally, 10% or less is sufficient, and in many cases, 8% or less is sufficient.

This large refractory block is pre-formed by putting this irregularly shaped mixture into a mold of a predetermined shape, and this molding can be done in various ways such as pour molding, cast molding, vibration molding, and ram molding. However, it is preferable to use a precast molded body.

The reason why it is necessary to form a molded object in advance even though it has an irregular shape is that it is easier to obtain a sufficient filling degree by vibration molding using a strong mold, and it is better to dry it beforehand. It's for a reason.

The physical properties of the molded product obtained in this way include a bulk specific gravity of 2.3 or more, a porosity of 13% or less, and a compressive strength (
kg/cm2) is 500 or more when cold and 4 at 1200℃.
00 or more, bending strength is 100 kg/c even at 1200℃
The softening temperature under load (T2) is about 1450°C or higher.

The furnace wall using refractory blocks with ventilation holes according to the present invention facilitates the release of volatile components contained in tar, pitch, etc., and makes it easier to use large blocks, which greatly simplifies the furnace construction work. It has many advantages, such as not only making it more effective but also promoting the firing of the product to be fired, and its industrial value is enormous.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view showing an example of a conventional firing furnace, FIG. 2 is an explanatory vertical cross-sectional view showing an example of the firing furnace of the present invention, and FIG.
Figures 8 through 8 are perspective views showing some examples of refractory blocks used in the furnace wall structure of the present invention. In the drawing, 1 is a firing chamber, 2 is a carbonaceous product to be fired, 4 is a side wall, 5 is an intermediate wall, 7 is a combustion gas flow path, 8 is a refractory block, 9 is a cavity, and 10 is a firing car. The surface area 24 indicates a ventilation hole, respectively.

Claims (1)

[Scope of claim for utility model registration] 1. A carbon fiber whose side walls and/or intermediate walls are constructed from fireproof blocks that have a hollow part in the center and a large number of ventilation holes in the thickness direction in the form of elongated slits in the wall forming the hollow part. Furnace wall structure of quality product firing department. 2. The furnace wall structure according to claim 1, wherein the side walls and/or intermediate walls are constructed of refractory blocks having a vent hole width of 10 mm or less. 3. The wall thickness of one block forming the firing chamber is 3600c.
The furnace wall structure according to claim 1 or 2, which uses a large refractory block having a size of m2 or more. 4. The furnace wall structure according to claim 3, which is a utility model, and is formed by using a large refractory block having a wall surface roughness of 10,000 cm2 or more. 5. The contact area of one cavity with combustion gas is 3600
The furnace wall structure according to claim 1, which is constructed of refractory blocks having a size of cm2 or more. 6. A request for registration of a utility model in which at least an intermediate wall is constructed from one fireproof block forming a cavity, in which ventilation holes are provided on both side walls forming the cavity. The furnace wall structure according to any one of items 1 to 5.