JP2002115011A - Structure for tuyere lining in refining furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of bricks for a tuyere part in a refining furnace. SOLUTION: The tuyere for blowing gaseous oxygen and inert gas, such as gaseous argon, by inserting a metal-made pipe disposed at the lower part of a side wall in the refining furnace, is constituted with the brick 5 for the tuyere part, composed of a tuyere brick 7 and a tuyere receiving brick 8 disposed in this surrounding part, and further, this brick 5 for the tuyere part is peculiarly constituted of a carbon-contained refractory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tuyere lining structure for a refining furnace such as an AOD furnace.

[0002]

2. Description of the Related Art An inert gas such as argon or nitrogen is blown together with oxygen gas into molten steel to reduce the partial pressure of generated CO gas, thereby efficiently oxidizing valuable metals such as Cr while efficiently decarburizing. AOD (Ar
smelting furnace (AO) using the gon oxygen decarburization method
D furnace) is widely used mainly as a smelting furnace for stainless steel.

As shown in FIG. 6, a cross-sectional view of one example of the above-mentioned AOD furnace is shown below the side wall 1a of the AOD furnace 1.
It has six tuyeres 2 from which oxygen gas and argon gas are blown into the furnace to perform refining while stirring molten steel. The tuyere 2 is constituted by a hole which penetrates a brick constituting the side wall portion 1a in a longitudinal direction thereof, and has a structure in which a gas tuyere pipe made of a double pipe is inserted into this hole to blow gas. ing.

Since the refractory lining 3 of the AOD furnace 1 is used under severe conditions due to the high temperature inside the furnace and the long refining time, high-temperature fired magnesia generally has excellent corrosion resistance at high temperatures. Chrome bricks and calcined magnesia-dolomite bricks are used including the tuyere 2 (Japanese Patent Application Laid-Open Nos. 7-157361 and 57-32318).

[0005]

The tuyere brick used for the tuyere 2 disposed on the side wall 1a of the AOD furnace 1 is heated during refining by exposing its working surface to molten steel. At the same time, gas cooling is performed through a metal pipe inserted into the inside, so that a sharp temperature gradient is generated inside the tuyere brick to generate thermal stress.

[0006] After tapping, the temperature drops rapidly due to gas cooling by the tuyere pipe, and a large thermal shock is applied during the next steel receiving.

[0007] Therefore, the tuyere brick has a severe temperature gradient inside the brick and a portion where the temperature fluctuates greatly. Therefore, the tuyere brick is made of an oxide-based material such as a magnesia-chrome brick or a dolomite brick as in the prior art. The use of bricks did not prevent damage due to spalling.

On the other hand, as a material having excellent spalling resistance, there is a carbon-containing refractory such as MgO-C, which is used in converters and the like (JP-A-6-184617 and JP-A-6-220517). ).

However, the stainless steel refining furnace A
In the case of an OD furnace, the operating temperature is extremely high, 1700 to 1800 ° C., and it is considered that the OD furnace may be damaged by oxidation or a reaction between MgO and C. Therefore, sufficient durability cannot be obtained with a carbon-containing refractory. Was.

Therefore, the present inventors have paid attention to the fact that tuyere bricks themselves in a refining furnace operating at high temperature are gas-cooled by tuyere pipes, and tuyere bricks and tuyere receivers arranged around the tuyere bricks The conventional problem is solved by configuring the brick with a carbon-containing refractory.

[0011]

SUMMARY OF THE INVENTION As a means for solving the problems of the above prior art, the present invention is directed to a tuyere arranged at the lower part of the side wall of a smelting furnace for inserting a tuyere pipe to blow an inert gas. And a tuyere brick consisting of a tuyere receiving brick disposed around the tuyere brick. The tuyere brick is made of a carbon-containing refractory.

The carbon-containing refractory contains 3 to 25% by weight of C, and 75% of MgO and / or Al ₂ O ₃ as an aggregate.
It is preferable that the composition be made up to 97% by weight as a main component.

The tuyere brick is made of magnesia.
It is preferred to line with chrome or dolomite bricks.

Further, the tuyere part brick preferably has a thickness of 300 mm or less, from which the tuyere cooling effect is exerted from the inner periphery of the pipe insertion hole provided in the tuyere brick. An interchangeable sleeve structure may be provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the embodiments shown in the drawings and the same reference numerals will be used for the portions common to FIG.

FIG. 1 shows, as an example of a refining furnace to which the present invention is applied, a furnace bottom 1b of an AOD furnace 1 and a side wall 1a close thereto.
FIG. 2 shows a cross section corresponding to AA in FIG.

The bricks 4 forming the inner surface of the side wall 1a of the AOD furnace 1 have a structure that is long and close to the side wall 1a.
The tuyere brick 5 to be incorporated into the porcelain has a structure that is long in the horizontal direction similarly to the brick 4 described above.

As shown in FIG. 3, the tuyere brick 5 penetrates in a longitudinal direction through a pipe insertion hole 6 for inserting a tuyere pipe for blowing an inert gas such as oxygen gas or argon gas. And the tuyere brick 7
And the tuyere receiving bricks 8 arranged around the tuyere. These tuyere bricks 7 and the tuyere receiving bricks 8 are made of MgO-C, A
It is constituted by _{l 2 O 3 -C, Al 2} O 3 carbon-containing refractories such -MgO-C. In this case, the content of C is preferably 3 to 25% by weight.

As the brick 4 constituting the inner surface of the side wall 1a of the AOD furnace 1, magnesia-chromium or dolomite brick is used. The magnesia - When using chromium bricks are blade to prevent Fe ₂ O ₃ and Cr ₂ O ₃ in the brick is being reduced metal by the carbon in the MgO-C of the tuyere portion brick 5 It is desirable to apply mortar around the opening brick 5.

The surroundings of the tuyere brick 5 are hardly cooled by the tuyere pipe and become higher in temperature than the tuyere brick 5. At high temperatures, the magnesia-carbon reaction and the oxidation of carbon are promoted, and Damage to refractory contained increases sharply.

Therefore, it is preferable to use a magnesia-chromium brick or a dolomite brick that does not contain carbon around the tuyere brick 5 because it has better corrosion resistance than carbon-containing refractories at high temperatures.

Further, since there is no cooling effect from the tuyere pipe, there is no temperature change, and as a result, spalling damage, which is a drawback of magnesia-chromic brick and dolomite brick, is less likely to occur.

In the illustrated embodiment, the tuyere brick 7 of the tuyere brick 5 has a sleeve structure having a tapered tubular shape with a circular cross section as illustrated in FIG. The tuyere brick 7 can be inserted into and removed from the tuyere 8 so that the tuyere brick 7 can be replaced.

In this case, if the tuyere receiving brick 8 around the tuyere brick 7 is made of magnesia-chrome brick, it is easily broken, so that it is difficult to form the tuyere brick 7 into a sleeve structure. By making the brick 8 made of a carbon-containing refractory, the above-mentioned sleeve structure can be adopted, and only the tuyere brick 7 can be replaced and repaired.

The tuyere brick 7 may have a rectangular cross section as illustrated in FIG. 5, and the tuyere receiving brick 8 may have a circular cross section. The tuyere brick 7 and the tuyere receiving brick 8 may be divided into a plurality in the axial direction or the circumferential direction.

The tuyere brick 5 has such a thickness that the tuyere cooling effect from the inner periphery of the pipe insertion hole 6 of the tuyere brick 7 can be exerted, and preferably has a thickness of 300 mm or less.

Table 1 shows examples 1 to 6 in which the dimensions (see FIGS. 3 and 4) of the tuyere brick 5 according to the present invention and the chemical composition of the brick are combined, and a tuyere having the same structure as the present invention. Part brick 5
Comparative Examples 7 to 9 in which the dimensions (see FIG. 4) and the chemical composition of the brick are combined are shown. In addition, the durability of the example and the comparative example based on the damage speed of the tuyere brick in the actual furnace is shown.

Although the embodiment shown here and the comparative example have a sleeve structure, the durability of the actual furnace is compared when the sleeve is not replaced.

[0029]

[Table 1] Table 2 shows that in the conventional structure having no tuyere receiving brick, the tuyere brick and the side wall 1a were made of magnesia-chrome brick (Comparative Example 10) or dolomite brick (Comparative Example 1).
The comparative examples 1) and the durability of these comparative examples are shown.

[0030]

[Table 2] In the above, the same brick is used as the tuyere brick in Example 3 and Comparative Example 7, and in Example 6 and Comparative Example 8,
The dimensions of the tuyere bricks are different, and the comparative examples 7 and 8 have large tuyere bricks, and the cooling effect from the tuyere pipe is difficult to cover the entire brick, so that the erosion is large.

In Comparative Example 9, the size of the tuyere brick was determined in Example 2.
Same as above, but spalling damage is large due to low carbon content.

As can be seen from the evaluation results in Tables 1 and 2, all of the examples of the present invention have an index of more than 100, while the comparative examples show values of an index of 100 or less. It shows the advantage of durability according to the invention.

[0033]

As described above, according to the present invention, a tuyere brick having a pipe insertion hole for blowing a gas for refining, and a tuyere receiving brick surrounding the tuyere brick are made of M.
_{gO-C, Al 2 O 3} -C, Al by constructing at 2 O 3 -MgO-C carbon-containing refractories made of a tuyere brick itself be a tuyere of refining furnaces hot operation is Because it is gas cooled, it has excellent spalling resistance,
The durability can be greatly improved as compared with conventional magnesia-chromic bricks and dolomite bricks.

According to the third aspect of the present invention, if the tuyere bricks are lined with magnesia-chromium brick or dolomite brick, the tuyere pipes can be formed at low cost with low-grade materials. As a result, the temperature does not change, so that spalling damage is less likely to occur, and a structure having excellent durability can be obtained.

Further, since the tuyere brick can be replaced as a sleeve structure as in the fourth aspect, a structure that can replace only the tuyere brick when the tuyere brick is damaged is adopted. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view when the present invention is applied to an AOD furnace.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view showing an example of a tuyere brick according to the present invention.

FIG. 4 shows an example of a tuyere brick in the present invention;
(A) is an end view of an inner end, (b) is a plan view, (c) is an end view of an outer end, and (d) is a side view.

FIG. 5 is a perspective view showing another embodiment of the tuyere brick.

FIG. 6 is a longitudinal sectional view of an AOD furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AOD furnace 1a Side wall part 3, 4 Brick which comprises a side wall part 5 Tuyere part brick 6 Pipe insertion hole 7 Tuyere brick 8 Tuyere receiving brick

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F27D 3/16 C04B 35/10 G (72) Inventor Tetsuro Kasahara 1850 Minato, Wakayama-shi, Wakayama Sumitomo Metal (72) Inventor Shigeyoshi Morishita 4-7-1 Kudankita, Chiyoda-ku, Tokyo Shinagawa White Brick Co., Ltd. (72) Inventor Minoru Sudo Kudankita, Chiyoda-ku, Tokyo 1-chome No.1 item Kawahira Brick Co., Ltd. F term (reference) 4G030 AA07 AA36 AA60 BA27 GA09 4K002 BG01 4K013 BA00 CA09 CA11 CA21 CF19 4K055 AA02 AA04 MA05

Claims (5)

[Claims] 1. A tuyere comprising a tuyere brick and a tuyere receiving brick disposed around the tuyere disposed at a lower portion of a side wall of a refining furnace for inserting a tuyere pipe and blowing an inert gas. A tuyere lining structure for a smelting furnace, wherein the tuyere brick is made of a refractory material containing carbon. 2. The carbon-containing refractory contains 3 to 25% by weight of C, and 75% of MgO and / or Al ₂ O ₃ as an aggregate.
2. The tuyere lining structure of a smelting furnace according to claim 1, which is constituted by about 97% by weight as a main component. 3. The tuyere lining structure of a refining furnace according to claim 1, wherein said tuyere brick is lined with magnesia-chrome brick or dolomite brick. 4. The tuyere brick has a tuyere cooling effect from the inner periphery of a pipe insertion hole provided in the tuyere brick.
The tuyere lining structure of a refining furnace according to any one of claims 1 to 3, wherein the wall thickness is not more than 00 mm. 5. The tuyere lining structure of a refining furnace according to claim 1, wherein said tuyere brick has a replaceable sleeve structure.