JP2876955B2 - Repair method for converter type refining vessel with gas injection tuyere - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of repairing a bottom-blown gas injection tuyere of a converter type refining vessel having a bottom-blowing function.

[0002]

2. Description of the Related Art FIG. 2 is a vertical sectional view of a bottom tuyere of a converter type smelting reduction furnace. The tuyere 12 is formed from the nozzle 4 and the tuyere brick 3. In FIG. 2, reference numeral 4 denotes a cylindrical nozzle into which Ar gas or N ₂ gas is blown in the direction of arrow A. Reference numeral 3 denotes a tuyere brick made of a magnesia-carbon refractory, which firmly holds the nozzle 4. Furnace wall refractory 2
Holds the tuyere brick 3. The furnace wall refractory 2 is made of magnesia-carbon refractory, and its main function is to hold molten steel.

In the vicinity of the surfaces of the nozzle 4 and the tuyere brick 3, the molten steel is vigorously stirred by the bottom blow gas, so that the refractory is greatly worn. Although the tuyere is cooled by the bottom blown gas, it is rapidly heated by the molten steel, and the thermal shock causes a crack due to a spalling phenomenon to occur and wear. On the other hand, in the related art, after tapping, a spraying repair, a baking repair, or a spray repair is performed while blowing a bottom blow gas from a bottom blow tuyere to form a protective layer by the repair body 11, and the protective layer forms a heat layer. Attempts have been made to alleviate the impact to extend the life of the tuyere.

[0004]

In the above repair work, the linear velocity of the bottom blown gas blown from the nozzle 4 is 3
Generally, it is 0 Nm / sec or less, and in this case, a repair body 11 which is porous and has no large opening is generated. This is because if the linear velocity of the bottom blown gas blown from the nozzle 4 is low, the sprayed repair material covers the nozzle 4 and the bottom blown gas barely blows out through small cracks generated in the repair body 11. It is because of that. In the case where the shape of the repair body 11 is such, the hole through which the bottom blow gas passes is small, and most of the bottom blow gas forms a gap at the boundary between the tuyere brick 3 and the repair body 11 and passes therethrough. Go.

As described above, when the repair body 11 is formed so as to cover the hole through which the bottom blow gas passes, if the flow rate of the bottom blow gas is increased at the time of the start of blowing after the repair, the repair body 11 becomes the tuyere brick. 3 easily peels off. Thereafter, the surface of the tuyere brick 3 is exposed to the molten steel due to the peeling and falling, and is rapidly heated. Therefore, the tuyere brick 3 generates thermal spalling and cracks and exfoliates, thereby increasing the wear rate and effect of repair. Is not fully exhibited.

The present invention has been made in order to solve such a problem. In a hot repair work for an inner wall of a converter type refining furnace, a protective layer of a repair body which is hardly peeled off from the surface of a tuyere brick is formed. Accordingly, an object of the present invention is to provide a repair method capable of extending the life of the furnace bottom tuyere.

[0007]

A method of repairing the inner wall of a converter type refining furnace according to the present invention is an irregular refractory which is performed while blowing gas from a bottom blown gas tuyere of a converter type refining vessel having a bottom blowing function. A hot repair method using a material, wherein a bottom blown gas is supplied from the tuyere at a linear flow rate of 50 Nm / sec to 500 Nm.
It is characterized in that hot repair is performed while passing in the range of / sec.

[0008]

By setting the linear flow velocity of the bottom blown gas within the above range, a repair body having a large opening at the tip of the tuyere can be formed. Linear flow velocity of bottom blown gas is 50 Nm / sec
If it is less than c, a large opening is not formed in the repair body. or,
If the linear flow velocity exceeds 500 Nm / sec, the tuyere is cooled by the cooling effect of the bottom blown gas, the repair material does not sinter, and a normal repair body is not formed. Therefore, it is necessary to keep the linear flow velocity in the above range. When the repair body has a large opening, if the flow rate of the bottom blown gas is increased at the start of blowing after repair, the bottom blown gas easily flows through this opening, and the repair body peels off from the surface of the tuyere brick. Never fall off.

[0009]

An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the same parts as those in FIG. In this repair method, a magnesia-based irregular-shaped refractory is used as a repair material, and the bottom blown gas is supplied from the nozzle 4 at a linear flow rate of 50 Nm / sec to 500 Nm / s.
While spraying in the range of ec, thermal spray repair, baking repair, or
Perform hot repair such as spray repair. For baking repair, a magnesia grain suspended in phenolic resin was used for nozzle 4
Around the tuyere brick 3. At this time, the volatile matter is driven out by the heat of the red-heated refractory, and then carbon and magnesia particles generated by decomposition of the phenol resin are sintered to form the repair body 1.

In the thermal spray repair, magnesia grains are injected into an ultra-high temperature flame to melt the magnesia grains, and spray the magnesia grains together with the flame to a repair site, thereby welding the magnesia to form the repair body 1. In the spray repair, magnesia grains are sprayed to a repair site with high-pressure air, and the magnesia grains are welded to form the repair body 1. These three
In some types of repair work, it may be effective to perform two or three types of repair work at the same time. When the linear flow velocity of the bottom blown gas becomes 50 Nm / sec or more, the repair body 1 has a large opening near the outlet of the nozzle 4.

FIG. 3 is a graph showing the relationship between the linear flow velocity of the bottom blown gas and the tuyere wear rate during repair. When the linear velocity of the bottom blown gas was repaired at 30 Nm / sec, the tuyere wear rate was 0.20 mm / Hr to 0.25 mm / Hr, but the linear velocity of the bottom blown gas was 50 Nm / sec to 15 Nm / sec.
If the tuyere is repaired at 0 Nm / sec,
It was 8 mm / Hr to 0.12 mm / Hr. That is, as is clear from the graph, a desirable situation where the tuyere wear rate is low is maintained when the linear flow velocity of the bottom blown gas is 50 Nm / sec or more.

If the linear flow velocity of the bottom blown gas is less than 50 Nm / sec, the tuyere wear rate increases drastically, and the tuyere life becomes extremely short. Also, the linear velocity of the bottom blown gas is 500 Nm / sec.
, The tuyere abrasion speed is from 0.20 mm / Hr to 0.
It became clear that the repaired body became brittle by rising rapidly to 25 mm / Hr. This is because the tuyeres are cooled near the tuyere and the repair material does not sinter due to the cooling effect of the bottom blow gas made of inert gas, making it difficult to form a normal repair body and making the repair body brittle. It is estimated to be.

In the conventional tuyere repair method, a large opening cannot be secured, so that the repaired body is blown off and peeled off during the operation of flowing a large amount of gas. Was about 2.5 times. In particular, even in a smelting reduction furnace having a long refining time, stable operating conditions were obtained. As a result, a highly reactive metal bath with good stirring was obtained, the refining reaction speed was increased, and the efficiency was improved.

[0014]

According to the method of the present invention, the life of the furnace bottom tuyere is increased by about 2.5 times. As a result, in the smelting reduction furnace, stable operating conditions were secured, the refining reaction speed was increased, and the efficiency was improved. In addition, the basic unit of refractory of the smelting reduction furnace could be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical section showing a furnace bottom tuyere when the method of the present invention is carried out.

FIG. 2 is a vertical cross section showing a furnace bottom tuyere when a conventional method is performed.

FIG. 3 is a graph showing the relationship between the linear flow velocity of the bottom blown gas and the tuyere wear rate during repair.

[Explanation of symbols]

 Reference Signs List 1 repair body 2 furnace wall refractory 3 tuyere brick 4 nozzle 11 repair body 12 tuyere

Continuation of the front page (72) Inventor Tomohiko Uchino 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. Examiner Shun Konbei (56) References JP-B-58-6876 (JP, B2) (58) Field surveyed (Int.Cl. ⁶ , DB name) C21C 5/48 F27D 1/16

Claims (1)

(57) [Claims] In a hot repair method using an irregular type refractory, wherein a gas is blown from a bottom-blowing gas blowing tuyere of a converter type refining vessel having a bottom-blowing function, the bottom-blowing gas is discharged from the tuyere at a linear flow rate of 50 Nm. / Sec-500Nm / sec
A method for repairing a converter type refining vessel having a gas injection tuyere, wherein hot repair is performed while passing in the range of c.