JPS5974211A - Bottom blowing tuyere of converter - Google Patents

Abstract

PURPOSE:To provide a bottom blowing tuyere of a converter which confines the damage arising from stirring of molten steel approximately in the range of the tuyere and decreased considerably the damage of a sleeve brick by positioning the convergent part of plural small-diameter blowing pipes within a range the prescribed ratio of diameters from the center of the tuyere and providing an allowance part for damage at the periphery of the convergent part. CONSTITUTION:The convergent part 120 of blowing pipes shown by a alternate long and two short dashes line in a bottom blowing tuyere 1 is positioned within 2/3 of the radius R of the tuyere. A refractory layer 1a of MgO-C constituting the tuyere 1 is formed around the part 120. The mushroom 7 formed in the upper part of the tuyere 1 is made correspondent to the part 120 by the above- mentioned constitution. As a result, the damage arising from stirring of molten steel is confined approximately within the range of the tuyere 1 and the allowance part for damage is provided by the layer 1a, whereby the damage of a sleeve brick 2 is considerably decreased.

Description

[Detailed description of the invention] The present invention relates to a bottom blowing tuyere for a converter.

As is well known, in order to strengthen the agitation in the steel bath and improve the refining efficiency, a top-bottom blowing converter operation is carried out in which oxygen is injected from the top-blowing lance and stirring gas is injected through the bottom-blowing tuyeres below the surface of the steel bath. It has been actively adopted in recent years.

As the stirring gas, OO2 + O2 gases, mixed gases thereof, or a small amount of oxygen gas added thereto are generally used, and the amount of injection is determined depending on the steel type and other refining conditions to achieve the above purpose. It is set and controlled appropriately.

By the way, the bottom blowing tuyere (hereinafter referred to as
Tuyeres (simply referred to as tuyeres) are installed by making holes in the steel shell and lining brick wall at the bottom of the converter, but these tuyeres and the brick wall near the tuyere's attachment point are exposed to the molten steel produced by gas injection. Due to direct contact with the strong agitation flow, it is subject to severe erosion and damage (hereinafter referred to as damage). Therefore, it is extremely important to improve the durability of the tuyeres and the brick walls in their vicinity against the above-mentioned damage effects in order to operate stable top-bottom blowing converters.
A number of devices and means have been proposed for this purpose.

Figure 1 shows the tuyere that the present applicant previously invented and applied for, and it is similar to the metal tube tuyere that has been commonly used in the past, or the single-hole tuyere made of refractory material. It has been confirmed that the stirring efficiency of the copper bath can be increased and its durability can also be improved. That is, in FIG. 1, l denotes a tuyere, and the tuyere 1 is made of MgO-0 yarn or dolomite refractory, and has a plurality of small diameter blowing pipes (hereinafter referred to as blowing pipes) 12'. It is focused and buried. The blow pipe 12 in this embodiment has a header 41 embedded in the base of the tuyere 1.
The stirring gas is blown into the furnace from the blowing pipe 12 through the head. The tuyere 1 is attached to a sleeve brick 2 buried in a brick wall 3 at the bottom of the hearth, and a tuyere holding brick 4
and is fixed by pace bricks 5. Note that 6 is a gas supply pipe for supplying stirring gas to the header 11.

Incidentally, in the tuyere 1 as well, as the operating time becomes longer, damage progresses as shown by the broken line X. In particular, since the pine mushroom 7 is formed above the tuyere 1 as is well known, the stirring gas also blows out to the side of the tuyere as shown by the arrow y, damaging the sleeve brick 2 in contact with the tuyere 1. was discovered. When the tuyere 1 reaches a predetermined amount of damage, it is replaced with a new tuyere 1 as shown in FIG. 2, but the sleeve brick 2, like the hearth brick 3, cannot be used for a long period of time. It's normal. Immediately after replacement, the tip of the tuyere 1 protrudes from the damaged sleeve brick 2.
For this reason, the rate of damage to the feathers in the protruding portions becomes significantly faster. In order to prevent this, the applicant has developed sleeve brick 2.
Attempts were made to repair the damaged parts by coating them with ZO2 slag or by spraying dolomite or other spraying agents, but it was confirmed that these types of repairs were unable to deal with the severe damage described above, and the rate of damage was extremely rapid. It was done.

The present invention was created as a result of repeated experiments and research based on the above-mentioned knowledge, and the gist thereof is to provide a converter bottom blowing tuyere in which a plurality of small-diameter blowing pipes are bundled and buried in a refractory. The converter bottom blowing tuyere is characterized in that the focusing part 7 is located within % of the radius from the center of the tuyere and a damage margin is provided around the focusing part.

The present invention will be described in detail below based on Examples.

FIG. 3 is a perspective view showing an embodiment of the tuyere according to the present invention, and FIG. 4 is a cross-sectional structural view showing how the tuyere shown in FIG. 3 is installed. In this embodiment, the blowing pipes 12 are buried within a radius S of the tuyere 1 in a concentrated manner. In other words, the convergence part 120 of the blowing pipe 12 shown by the two-dot chain line has a tuyere radius R.
It is located within % of The MgO-0 system constituting the tuyere 1 is arranged around the blowing tube converging section 120.

Alternatively, a refractory layer 1a made of dolomite or the like is formed.

As described above, in the tuyere l of the present invention, since the blowing pipes 12 are converged at the center of the tuyere l, the pine mushroom 7 generated on the upper part is also caused by the blowing pipe converging part 12 as shown in FIG.
It corresponds to 0.

As a result, damage caused by stirring the molten steel remains within the tuyere 1, that is, the refractory layer 1a serves as a damage allowance, and damage to the sleeve brick 2 is slightly reduced. FIG. 5 shows the results of investigating the damage rate of the sleeve brick 2 by varying the radius rf of the blowing pipe converging section 120 with respect to the radius R of the tuyere 1. As is clear from Fig. 5-
When becomes less than %, the damage rate of sleeve brick 2 decreases drastically,
The effect of the damage margin of the tuyere 1 was clearly confirmed〇 On the other hand, if the radius r of the blowing pipe convergence part 120 becomes too small, the blowing pipe 12 will be concentrated in the center of the tuyere 1, resulting in a small diameter. There is a possibility that the molten steel stirring effect, which is one of the excellent effects of the 12 or more blow pipes and the buried tuyeres 1, may be reduced. According to the experience of the present inventors, it has been confirmed that if - is % or more, the effect of the present invention can be exhibited without impairing the above-mentioned stirring effect.

As described above, the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional structural diagram showing an example of a tuyere embedded in a plurality of small-diameter blow pipe refractories. Figure 2 is a cross-sectional structural diagram showing the tuyere in Figure 1 after replacement. Fig. 3 is a perspective view showing an embodiment of the tuyere based on the present invention, Fig. 4 is a cross-sectional structural view of the tuyere shown in Fig. 3, and Fig. 5 is a chart showing the results of an investigation on the damage rate of sleeve bricks. . 1...Tuyere 11...Header 12...Blowing pipe ■20...Blowing pipe converging section 2...Sleeve brick 3...Brick Wall 4 ... Tuyere valve brick 5 ... - Pace brick 6 ... ... Gas supply pipe 11 ... ... Masamatsu Shroom Applicant: Nippon Steel Corporation No. 4 Figure 7 15m + V4 ぢぢ

Claims (1)

[Claims] In a converter bottom blowing tuyere formed by bundling a plurality of small-diameter blowing pipes and burying them in a refractory, the bundled part is set at a radius of % of the radius from the center of the tuyere.
A converter bottom blowing tuyere characterized in that a damage margin is provided around the converging part located within the range.