JPS6050272B2 - Furnace construction method for lining structure in high-temperature container - Google Patents

Description

[Detailed Description of the Invention] The present invention provides for the construction of lining structures for blast furnaces, converters, etc.
The present invention relates to the provision of a new means for building a furnace that is improved so as to prevent damage to the main firebricks, particularly cracking caused by thermal stress.

For example, in a high-temperature container (furnace) that uses a refractory brick structure as its lining, such as a blast furnace, it is no exaggeration to say that damage to the lining brick determines the lifespan of the container (furnace) or the time for repair. It is well known that the occurrence of cracks due to thermal stress is an important factor in the damage to bricks.

Now to explain the problem of cracking in refractory bricks, in Figures 1a and 1b, a shows a partial model diagram of a single refractory brick divided in half from the center, and a shows an FEM divided diagram. In the case of a steel shell, the lining structure is assembled in a ring shape using a plurality of firebricks 1, and the outer shell 2 and the bricks 1 are usually joined using a stamp 3. be. Here, only one part of a single firebrick is shown as a model because of its symmetry, taking into account the inserted joints for absorbing thermal expansion. In both figures a and b, the line CC indicates the center line. In such a model, during temperature rise during blast furnace operation, the temperature of only the inner surface of the brick 1 rises and thermal expansion occurs, as shown in Figure 1a, where the dotted line shows the initial shape and the solid line shows the shape at high temperature. In figure a, σ indicates the joint thickness. During this thermal expansion,
The refractory brick 1 comes into contact with the adjacent brick 1, and the contact state is as shown in FIG. be. Therefore, as shown in the compressive force model diagram in Fig. 3, in the area of approximately j on the inner surface side, the compressive force P is
receive. Therefore, if the partial compressive force is applied in the θ direction, the boundary point E between the area where the compressive force is acting and the area where the compressive force is not acting (long distance of L from the inner surface of the brick), that is, the singular point E ( 7) A tensile stress σγ is generated in the direction as shown in the distribution diagram in Figure 4, and by exceeding the tensile strength σB,
Cracking occurs from the singular point E on the inner surface. The present invention focuses on the mechanism of cracking, and effectively and accurately prevents cracking by improving the furnace construction of the lining structure made of refractory bricks and joints. Therefore, its characteristic feature is that in high-temperature containers that use a refractory brick structure as the lining of blast furnaces, converters, etc., the inner lining is constructed with refractory bricks and joints of the structure, and the inside of the container (furnace) (high temperature ) side is thicker, the joint thickness (gap between bricks) on the outside (low temperature) side of the container (furnace) is thinner, and the joint thickness (gap between bricks) is increased within one contact surface between adjacent bricks. The point is that the construction is carried out by changing the dimensions).

Describing the present invention in detail below based on the illustrated embodiment, in explaining the mechanism of cracking in the fireproof brick 1 mentioned above, what determines the tensile stress at the singular point E is not the compressive force P itself. , is the gradient of the compressive force P. Figure 5 shows a graph of this relationship, where the vertical axis is the generated tensile stress σ
γ, and the horizontal axis shows the lateral pressure gradient PO/L. As shown by curve A, if the gradient of compressive force P is steep, the tensile stress increases, and if the gradient is gentle, the tensile stress increases. It is clear that there is a decrease. That is, the compressive force P decreases, the tensile stress σγ
In order to reduce this, it is sufficient to increase the contact area between adjacent bricks 1 and 1 in hot conditions, and for this purpose, the furnace should be constructed using refractory bricks and joints, taking into account the expansion allowance in hot conditions. It will be a good thing.

As mentioned earlier, the temperature of a hot refractory brick is higher on the inner surface and lower on the outer surface, so heat. In order to compensate for the difference in expansion, it is possible to consider a construction in which the gap (joint thickness) between adjacent firebricks is changed. The present invention is characterized by such construction contents, and FIG. 6 shows one basic example thereof in comparison with the conventional method. That is, figure a shows the method of the present invention. , and FIG.
When taking the gap (joint) in 1a, make it larger in the part facing the inside of the furnace (high temperature part), and make it larger in the part facing the outside of the furnace (
In other words, this also means that the joint thickness toward the inside of the furnace is thicker, and the joint toward the outside of the furnace is thinner, and the thickness (larger and smaller) over the entire length of the gap (joint) is smaller. ) is assumed to gradually decrease from the inside of the furnace to the outside of the furnace. To specifically illustrate this in the case of a blast furnace in Fig. 6a, in Fig. 6a, on the inner side of the brick 1 facing into the furnace, the brick width:
a1 Temperature: Tal Brick gap: σA, . The hot shrinkage rate between AN is εa, and on the outer surface side of the brick 1 facing outside the furnace, the brick width: 1b1 Temperature: TOl Brick gap: σB, . If the hot shrinkage ratio between BB'' is εb, and the coefficient of thermal expansion is α, then in order to achieve the purpose of the present invention, if εa=εb, then both the inner and outer surfaces are adjacent to each other. The joining sides 1a, 1a are in uniform contact, making it possible to reduce the gradient of the compressive force P mentioned above and thus to reduce the tensile stress.

That is, It is sufficient if the formula is satisfied.

In the case of blast furnace, 1a: 0.81b. ．． Ta:1500
℃, Tb: If it is about 250℃, σa/σb-
The desired joint thickness (gap size between bricks) is approximately +5, and considering a certain width, 1.5 σa/
σb〈8. It is thought that guarding is effective, and within this range, as mentioned above, the joint thickness (gap between bricks) is gradually changed from the inside of the furnace to the outside of the furnace, and the All you have to do is build the furnace one by one. The present invention is as described above, and according to this furnace construction content, it is possible to effectively and accurately prevent the occurrence of cracks in firebricks, thereby preventing damage to the bricks, thereby shortening the life of the furnace, and frequently repeating the need for repairs. This means that relatively long-term operation can be guaranteed.

In particular, in the present invention, conventional refractory bricks are used as they are, and the joint thickness (gap between bricks) between adjacent refractory bricks 1 and 1 is simply the same joint thickness over the entire length extending inside and outside the furnace as in the conventional method shown in Figure 6b. (Unlike the same gap, it only needs to be changed as shown in Figure 6a, so it can be easily implemented without any particular difficulty, and it is highly effective. By reducing the gradient of the compressive force P shown in FIG.
The effect is precise, and there is no particular disadvantage in terms of materials or man-hours for furnace construction, and it is a great advantage as a measure to improve the lining structure of a high-temperature container using firebrick.

[Brief explanation of the drawing]

Figure 1 is an analytical model diagram of thermal deformation in firebricks, Figure 2 is an explanatory diagram of the contact state of the bricks at high temperatures, Figure 3 is a model diagram of the compressive force acting on the inner surface of the bricks, and Figure 4 is the tensile stress of the same bricks. Distribution diagram, Figure 5 is a graph of the relationship between tensile stress and lateral pressure gradient,
FIG. 6 is a diagram illustrating a comparison between an embodiment of the method of the present invention and a conventional method. 1...Firebrick, 2...Iron skin, 3.
... Stamp, 1a ... Joining side.

Claims (1)

[Claims] 1. In high-temperature containers using refractory brick structures as the lining of blast furnaces, converters, etc., when constructing the lining structure using refractory bricks and joints, the thickness of the joints on the (high temperature) side of the container (furnace) (gap) thicker, outside the container (furnace) (low temperature)
A lining structure for a high-temperature container, characterized in that it is constructed by reducing the side joint thickness (gap between bricks) and changing the joint thickness (dimensions of inter-brick gap) within one contact surface between adjacent bricks. Furnace construction method.