JPH01147013A - Metal refining vessel - Google Patents

Abstract

PURPOSE:To reduce thermal spalling and to facilitate the exchange of a damaged tuyere brick while still hot by using hexagonal columnar bricks as lining refractory bricks of a metal refining vessel such as converter or electric furnace of which the bottom forms a spherical recess and has tuyeres. CONSTITUTION:The furnace bottom forms a spherical recessed surface, and a hexagonal-column refractory brick is used as the lining brick for the various converters, electric furnaces, etc., having plural tuyeres at the bottom. The end face of the hexagonal-column brick is practically homologously reduced from the furnace axis toward the periphery, or the size of the end face of the brick is reduced in the circumferential direction from the furnace axis toward the periphery to easily form the spherical recessed surface at the bottom. As a result, the thermal spalling of the lining refractory brick can be reduced, plural tuyeres can be approached to each other, and the damaged brick can be easily exchanged while still hot.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a top-bottom blown converter, a bottom-blown converter, a bottom-blown electric furnace, etc., in which the bottom of the furnace forms a spherical concave surface and tuyeres are provided at the bottom of the furnace. The present invention relates to a metal refining vessel having a metal refining vessel.

[Conventional technology]

Conventionally, there are three known brick-laying structures for the bottom of the hearth: Ajiro-laying, inner-core bricklaying, and straight-line brickwork, and there are also some combinations of Ajiro-laying and straight-line bricklaying.

The end face shape of the bricks used in these stacking methods is quadrilateral, with straight stacking being rectangular, and core stacking being fan-shaped.

Also, Japanese Patent Publication No. 30-6680, Utility Model Publication No. 55-83
Japanese Patent No. 687 describes a method for constructing a curved ceiling for a furnace, in which bricks having hexagonal end faces are stretched.

However, the above-mentioned publications do not specifically describe means for forming a concave spherical surface, and cannot be applied to the construction of a hearth bottom having a tuyere.

[Problem that the invention seeks to solve]

In recent years, the stirring performance of blowing furnaces with bottom-blown tuyeres has been recognized and their use as reactors has been expanded, but the stress on the tuyeres has caused damage to the tuyere bricks to become more diverse, and the extent of the damage has increased. is also becoming more serious.

The most desirable condition for the tuyeres is when deposits, commonly called pine mushrooms, form on the tuyeres and the heating surface of the tuyere bricks, commonly known as the hot face, is protected. In fact, the harsher conditions have increased the frequency of pine mushroom detachment, accelerated erosion and cracking of the tuyere bricks, and caused the tuyere bricks to wear out in large units, shortening the lifespan of the hearth bottom.

One of the reasons for this is that the tuyere bricks are forcibly cooled by gas or powder-containing gas blown in at high pressure, and the large amount of heat flowing from the hot face creates a sharp temperature gradient within the bricks. It is at the point where thermal spalling is induced by rapid temperature gradients. This thermal spalling of tuyere bricks depends on the strength of the material itself, which determines how much temperature gradient the bricks can withstand, and the size of the bricks.

Another cause is mechanical spalling, such as warping cracks due to thermal expansion between bricks, local crushing due to intruded solidified metal, and the growth of microcracks due to vibration.

The dimensional accuracy and warpage accuracy of bricks has a tolerance of about ±1 mm, and perfect surface contact cannot be guaranteed in the event of expansion and warping, so local stress generation cannot be avoided from the perspective of dimensional accuracy. do not have. Normally, the thermal expansion stroke of the bricks is absorbed by inserting cardboard, but molten metal enters the gaps created by the heat and solidifies. This solidified metal causes localized crushing of the bricks and the formation of large cracks far from the hot face of the bricks.

That is, mechanical spalling occurs first in the tuyere bricks and perituyere bricks, shorting between adjacent tuyeres and forming extensive damage zones called tuyere rows or tuyere zones;
The damage zone is further gouged out at an accelerated rate during subsequent blowing, and this is the cause of the short lifespan of the hearth bottom.

As a result of performing an ASTM panel spalling test on a conventional smelting vessel using the above-mentioned quadrilateral bricks,
It was found that when a crack parallel to the hot face occurs in one brick, adjacent bricks also tend to crack due to tension and friction between the bricks.

In addition, conventional brick-splitting, which is based on the premise of replacing the tuyere in the case of each of the above-mentioned bottom blowing furnaces, often consists of a cylindrical vane Rossligue brick and a tuyere block surrounding it, and the tuyere block is a circumscribed In order to compete with bricks, it had to be made larger.

Therefore, a part of a tuyere block with a large cross-sectional area tends to spall in units of 50 to 150 m, which causes propagation spalling of the entire block and surrounding bricks.

The object of the present invention is to obtain an effective means for preventing damage to the hearth bricks mainly due to mechanical spalling, and thereby to prolong the life of the hearth bricks.

[Means for solving problems]

The present invention was completed based on the finding that propagation of cracks in bricks having substantially hexagonal end faces is significantly reduced.

This is because the distribution of strain is superior to the generation of thermal and mechanical stress, and even in structures, the entire system always moves in the direction of the minimum stress, and as a result, local spalling subsides. , propagation failure is suppressed.

The tuyere block has the role of guarding the brickwork at the hearth bottom from collapsing even if the tuyere sleeve is removed midway and replaced. Even if the block is removed, the surrounding area retains its hold, so the need for a large block can be completely eliminated. That is, according to the present invention, it is possible to make the tuyere bricks smaller, and by making the bricks smaller in cross section, thermal spalling can be significantly reduced.

As a result, it becomes easy to set the tuyere position, and it is possible to cope with an increase in the number of tuyeres, especially in a blowing furnace that blows a large volume of gas.

Hereinafter, the configuration of the present invention will be specifically explained.

FIGS. 1 and 2 partially show the structure of the bricks in the bottom of the furnace of the refining vessel of the present invention. FIG. 1 is a plan layout of each brick, and FIG. It is a figure showing the side surface of the arrangement brick seen from the line -■.

Although not shown, if the hearth bottom is flat, it can be lined simply with hexagonal bricks.

However, if the hearth bottom is curved (spherical), lining cannot be done in the same shape. Examples are shown in FIGS. 1 and 2.

Note that the hexagonal columnar bricks in this case refer to straight and tapered bricks. In addition, although Figures 1 and 2 show an example in which the center of the hearth is the center of the lining, it is of course possible to solve the problem using the same concept even if the center of the lining and the center of the hearth are shifted. .

In these figures, when the distance between the parallel ridges of the bottom of the hexagonal columnar brick placed at the furnace axis with a spherical radius R1 is ao, the angle θ formed by the core of the hexagonal columnar brick that is farther away from the axis is The following relationship holds true.

That is, the circumferential length φ formed by rotating the point P7 in FIG. 2 around the furnace axis is φ7=2πR51nθ7...■.

However, the length of R7 in the bottom view of FIG.
Since it is (3/π) times the circumference and seven hexagonal prism bases are included therebetween, the following relational expression holds true.

Since φri=2πR51nθ7, rearranging the equation, a, = −5in θ7N el I . . . ■■. Here, a indicates that the length of the hexagonal surface in the circumferential direction gradually decreases as it moves away from the outer periphery in order to form a spherical surface. Here, when formula (2) is generalized, it is expressed as a, , = (R/n) si mouth θ, . . . .

Figure 1 a. If it is fixed, except for the hexagonal shaft bricks, all the remaining bricks will become distorted little by little in the circumferential direction. Here, the hexagonal axis brick is θ ~ 70 in the diagram.
These are numbered bricks.

The metal refining vessel of the present invention can be fully applied not only when the center of the bottom lining is located at the center of the furnace bottom, but also when the center of the bottom lining is offset from the center of the furnace bottom.

〔Example〕

Example 1 The R of a converter with a general spherical hearth bottom is R=5500~
8500mm, and the brick splitting is empirically a=10
I think 0 to 200mm is appropriate, so as an example, R = 65
00mm, brick length β = 1200mm, a,' =
A calculation example for the case of 150mm and ao=184mm is as follows: a. = 184. R=6500. When n = 8, θ, = 12.975°, and inserting the above result into equation (■), a, = 1
It becomes 82.4. According to this, the calculation results for ao to alo are shown in Table 1.

Table 1: Parallel ridge path! Change in length in the circumferential direction of an n-circular brick when ao brick is placed on the axis and the distance between the parallel edges of hexagonal axial bricks is ao Table 1 shows the length of the bricks in the drawing. So, 2-4
mm mortar joints are used, so for example joint layer 2
．． If it is 5mm, the value after subtracting it is 184-2,5
= 181.5mm is the actual brick length.

Bricks are allowed to have a dimensional accuracy of ±1.0mm to ±0.5mm, so the brick split lengths in Table 1 are divided into two or three types of dimensions, reducing the number of types and reducing the number of bricks.

This has become possible for both users.

In reality, since the entire circumferential direction becomes thinner, the diameter direction also becomes slightly shorter. The points where the three edges of the hexagonal columnar object also come into contact do not match due to the R sphere, but in reality R is larger than the dimension a, so this is within the error range.

One way to compensate for this error is to construct a spherical surface by a combination of hexagonal prisms with fixed brick lengths in the axial direction on each side and small brick lengths in the circumferential direction. I kept it within the range and adjusted it using mortar joints.

A similar trial could be started by bringing the tops of three bricks to the hearth axis.

Embodiment 2 As the next embodiment, there is a method of reducing the size of the outer peripheral bricks in a substantially similar manner.

In this case, the operation of the brick-splitting formula described above is different.

In the previous example, if the 2° of the brick in the diametrical direction of the hexagonal axis was fixed, θ. is θ, = 1.622°, θ2−1.62
2°X 2 = 3.244°,...θ, = 1.6
It was 22°×n.

In the method of reducing the size of some bricks on the outer periphery in a similar manner, for example, when bricks with a parallel ridge path fiao are placed on the furnace axis, the relationship between ao and θゎ on the nth turn is as follows. However, since θ is different, a7 is also necessarily different. θ7 in this case is roughly expressed as n.

a7 and θ obtained from these two equations. The values are shown in Table 2.

As in the previous example, the premise is that R = 6500° center, a o = 184 mm, a o' = 150 mm,
A brick with a length of 1200 marks was placed.

Table 2 Distance a between parallel ridges of the n-th brick when the bottom surfaces of the two hexagonal columnar bricks become smaller from the core axis to the outer periphery in a substantially similar manner. and the hearth shaft.

a9 Example of trial calculation of angle θ formed by brick shaft Actually, the calculated values in Table 2 were also obtained for the hot face, and the mortar joint area was subtracted by 2.5 mm to determine the brick shape.

Since the tolerance of the bricks was set to ±0.5m+n, there were four types of dimensional classification.

〔Effect of the invention〕

The present invention described above can provide the following effects.

When stress is generated around the tuyeres, bricks with hexagonal facets have better dispersion of strain than conventional bricks with squared facets, so crack propagation is significantly reduced. It was done.

This made it possible to reduce the size of the 0-tuyere bricks and reduce thermal spalling.

C. The tuyere can be brought closer than before, making it easier to design the tuyere position.

2. Hot replacement of worn out tuyeres is now possible without risk.

E. Tuyere design is now possible even in blowing where a large volume of gas is blown.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the arrangement of bricks, and FIG. 2 is a side view of the arranged bricks as seen from the line ■-■ in FIG. Figure 1

Claims (1)

[Scope of Claims] 1. A metal refining vessel characterized in that the bottom lining of the furnace is made up of substantially only hexagonal columnar bricks. 2. The metal refining vessel according to claim 1, wherein the center of the furnace bottom lining is located at the center of the furnace bottom. 3. The metal refining vessel according to claim 1, wherein the center of the furnace bottom lining is offset from the center of the furnace bottom. 4. The bottom lining of the furnace is comprised essentially only of hexagonal columnar bricks, and the end faces of the hexagonal columnar bricks are formed in a substantially similar shape from the furnace axis toward the outer periphery to form a concave surface. A metal refining container featuring: 5. The metal refining vessel according to claim 4, wherein the end face of the hexagonal columnar brick constituting the spherical surface has a circumferential size smaller from the furnace axis toward the outer periphery.