JP3286190B2 - Gas injection nozzle for molten metal furnace and its wear control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas injection nozzle used for agitating and refining molten metal in the field of metallurgy, and a method for managing its wear.

[0002]

2. Description of the Related Art Recently, in a steelmaking process, a gas injection nozzle for stirring and refining gas is provided at the bottom of a furnace in an upper-bottom blow converter, an AOD furnace, an electric furnace, or the like. It has been found that the operating effect and the metallurgical effect can be improved by blowing active gas or the like to forcibly agitate the molten metal.

[0003] As a technique widely used at present, a wind box is arranged at the end of a gas supply pipe as disclosed in Japanese Patent Publication No. 61-46523, and the gas supply pipe is dispersed in a narrow tube for gas injection. However, there are many problems in gas distribution to each capillary and safety.

[0004] For example, particularly during operation, when a thermocouple embedded in a nozzle is used more than the limit due to a lack of a thermocouple embedded in a nozzle for temperature control due to insertion of molten metal, a factor that causes steel leakage from a gas supply pipe is included. In.

[0005] Further, in the gas injection nozzle provided with the wind box as described above, there is a concern that the gas flow rate may be non-uniform between the gas injection thin tube at the center of the nozzle and the gas injection thin tube at the peripheral portion. . In order to solve this problem, Japanese Patent Application Laid-Open No. 63-140027 discloses a large-diameter gas inlet having an inner diameter substantially close to the outer shape of a bundle of bundled gas-introducing tubes. It is proposed to connect to the pipe.

However, there is no gas leakage at the portion where the aggregate of the gas introduction thin tubes is connected to the large-diameter gas introduction tube, and it is extremely difficult to completely connect the gas introduction tubes. Even so, a weld leaks easily due to thermal strain during use, and gas leakage occurs. Once gas leaks, there is a danger of molten steel being inserted into the gas introduction capillary due to a decrease in pressure in the gas introduction capillary, and steel leakage occurring.

[0007]

As described above, as described above,
According to the prior art, a gas injection nozzle that injects gas into the molten metal has not yet achieved a stable gas injection and a stable and safe gas injection that has not completely achieved steel leakage by inserting the molten metal. A nozzle was desired.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in order to solve the above-mentioned problems, a plurality of gas injection narrow tubes are buried in a refractory of a gas injection nozzle. In the gas injection nozzle for molten metal furnace,
The lower end portion of each gas injection thin tube so that the stirring gas can be uniformly and stably injected into each gas injection thin tube, and the molten metal is solidified when the molten metal flows in so that the gas injection thin tube can be closed. The present invention provides a gas injection nozzle for a molten metal furnace, characterized in that a gas distribution section in which groove-shaped gas injection flow passages communicate with each other is provided.

Further, when the molten metal flows into the gas injection narrow tube using the gas injection nozzle to be in a closed state, a change in the gas flow rate or gas pressure supplied to the gas injection nozzle is detected to detect the gas. An object of the present invention is to provide a method for managing wear of a gas injection nozzle for a molten metal furnace, which is characterized by managing the wear state of the injection nozzle.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas injection nozzle for a molten metal furnace in which a plurality of gas injection thin tubes are embedded in a refractory of a gas injection nozzle, and a stirring gas is uniformly and stably applied to each gas injection nozzle. A groove-shaped gas injection flow passage communicates with the lower end of each gas injection narrow tube so that the molten metal solidifies and closes the gas injection thin tube when the molten metal flows in. A gas distribution section is provided, and when the molten metal flows into the gas injection narrow tube and becomes in a closed state, a change in the gas flow rate or gas pressure supplied to the gas injection nozzle is detected to reduce the wear state of the gas injection nozzle. An object of the present invention is to provide a gas injection nozzle for a molten metal furnace and a method for managing its wear, which can be managed.

As shown in FIG. 1, the gas injection nozzle 1 is formed of a predetermined refractory 2 in the shape of a truncated cone with a cut-out head, and a plurality of ceramic or metal gas injection thin tubes inside the refractory 2. 3 and a gas distribution unit 4
Is connected to the gas supply pipe 5 so that the stirring gas can be blown out.

As shown in FIG. 2, the gas distribution section 4 hermetically joins the upper and lower plates 6 and 7 of a ceramic or metal material, which are vertically flanged, by welding, bolting, or the like. 6
The lower end of the gas injection thin tube 3 is hermetically bonded to the lower plate 7, and the lower plate 7 has a groove shape for uniformly flowing the gas from the gas supply pipe 5 to the gas injection thin tube 3 of the upper plate 6. The gas inflow passage 8 is concavely formed in a radial, concentric or parallel shape.

A thermocouple (not shown) is usually buried in the gas injection nozzle 1 to detect a rise in temperature and manage the state of wear of the gas injection nozzle 1, but the thermocouple may be cut off. Even when the operation is performed after the remaining dimensions are unknown, a predetermined narrow groove is formed so that the molten metal flowing into the gas blowing flow passage 8 of the gas distribution unit 4 is cooled and solidified. .

The gas injection passage 8 has a cross section equal to or slightly larger than the diameter of the gas injection thin tube 3 so that the molten metal solidifies spontaneously as described above. To prevent the occurrence of steel leakage.

By configuring the gas distribution section 4 as described above, the stirring gas can be stably blown in uniformly and stably.
Even if the molten metal flows into the gas injection narrow tube 3, it can be cooled and solidified in the gas injection flow passage 8 and prevented from leaking from the gas supply tube 5, and the fluctuation of the gas supply flow rate and pressure can be reduced. This is to detect and determine the wear state of the gas injection nozzle 1 so that it can be dealt with.

[0016]

1 to 5 show various embodiments of the present invention. In the embodiment of FIG. 2, the gas injection narrow tube 3 is arranged in a radial single circle on the upper plate 6 of the gas distribution unit 4, and the gas injection flow passage 8 is arranged in the radial groove on the lower plate 7. Things.

In the embodiment shown in FIG. 3, the gas injection thin tubes 3 are arranged on the upper plate 6 of the gas distribution section 4 in a radially double concentric manner, and the gas injection passage 8 is formed on the lower plate 7. It is provided with a double concentric recess so as to communicate with the connecting groove 9 of a radial groove.

Further, in the embodiment shown in FIG. 4, the gas injection thin tubes 3 are disposed symmetrically on the upper plate 6 of the gas distribution unit 4 and the gas injection flow passages 8 are formed symmetrically on the lower plate 7. Are arranged in parallel with each other and communicate with each other through the connecting groove 10.

In the embodiment shown in FIG. 5, the gas blowing passage 8 is radially recessed in the upper plate 6, and the gas blowing thin tube 3 is provided at each end thereof.

In this way, the gas distribution passages can be freely arranged in the gas distribution section so as to be able to blow out uniformly from each gas injection narrow tube, and the gas is supplied so as not to generate steel leakage. The blowing passage is formed in a groove shape having a predetermined width.

A flow rate comparison test between the above-described structure of the gas distribution unit shown in FIG. 2 and the conventional system of the distribution type into a gas blowing thin tube having a wind box structure was conducted by air ventilation.

The gas-injection thin tubes used in the actual machine were a total of 11 tubes having an inner diameter of 1.5 mm and a total length of 980 mm, and the results of the test showed that they were almost equivalent as shown in FIG. And, even when the air pressure increased, the fluctuation of the flow rate was small, and the flow rate of 135 to 164 Nl / min at 1.5 to 2.0 kgf / cm ² used in the actual furnace could be secured.

[0023]

As described above, in the present invention, when the gas for stirring is supplied to the gas injection nozzle, the gas is distributed uniformly in the gas injection flow passage in the gas distribution section, and the gas is supplied from the gas injection narrow tube. And the molten metal can be stirred and refined.

The gas injection nozzle wears out as the number of operations increases, and even if the molten metal flows into the gas injection narrow tube and reaches the gas distribution unit at the end of the operation, the amount of gas that melts the gas distribution unit is reduced. Coagulates spontaneously without reaching, ensuring safety.

Therefore, even if the remaining dimensions cannot be confirmed due to the breakage of the buried thermocouple, slag, metallurgical residue, or the like, a part of the gas blowing thin tube is blocked as described above. By detecting fluctuations in the gas flow rate and gas pressure, wear control of the gas injection nozzle can be performed, and accidents due to steel leakage can be prevented beforehand and safe operation can be achieved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of one embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view of a gas distribution unit of the above (a), a bottom view of an upper plate (b), a plan view of a lower plate (c),

FIG. 3 is a sectional view (a) for explaining a gas distribution section of another embodiment of the above, a bottom view (b) of an upper plate, a plan view (c) of a lower plate,

FIG. 4 is a cross-sectional view for explaining a gas distribution unit of another embodiment of the present invention (a), a bottom view of an upper plate (b), a plan view of a lower plate (c),

FIG. 5 is a cross-sectional view for explaining a gas distribution section of still another embodiment of the present invention (a), a bottom view of an upper plate (b), a plan view of a lower plate (c),

FIG. 6 is a diagram showing the relationship between the gas supply pressure and the gas blowing flow rate of the gas blowing nozzle of the present invention and the conventional gas blowing nozzle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gas injection nozzle 2 ... Refractory 3 ... Gas injection thin tube 4 ... Gas distribution part 6 ... Upper plate 7 ... Lower plate 8 ... Flow path for gas injection

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Sumio Yamada 2-3-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation (58) Field surveyed (Int. Cl. ⁷ , DB name) C21C 5/48 C21C 7/00 C21C 7/072 F27D 7/02

Claims (4)

(57) [Claims] In a gas injection nozzle for a molten metal furnace having a plurality of gas injection thin tubes embedded in a refractory of a gas injection nozzle, a stirrer gas is uniformly and stably injected into each gas injection thin tube. At the lower end of each gas injection thin tube, a gas distribution portion is provided at the lower end of each gas injection thin tube so that a groove-shaped gas injection flow passage communicates with each other so as to solidify the molten metal upon inflow of one molten metal and close the gas injection thin tube. A gas injection nozzle for a molten metal furnace. 2. The gas injection nozzle for a molten metal furnace according to claim 1, wherein the groove-shaped gas injection flow passage of the gas distribution section has a cross section equal to or slightly wider than the gas injection thin tube. 3. A gas-distributing gas-injecting flow passage of a gas distributing part is arranged radially, concentrically, or in parallel,
The gas injection nozzle for a molten metal furnace according to claim 1, wherein a gas injection flow passage is formed so that when the molten metal flows into the gas injection narrow tube, the molten metal is cooled and solidified in the gas distribution unit. 4. A gas injection nozzle for a molten metal furnace in which a plurality of gas injection narrow tubes are buried in a refractory of the gas injection nozzle, in which a stirring gas is stably injected uniformly and in an inflow of molten metal. In order to solidify the molten metal and close the gas injection capillary at the time, a gas distributor is provided at the lower end of each gas injection capillary to communicate with a groove-shaped gas injection flow passage, and a gas injection nozzle is used. When the molten metal flows into the gas injection narrow tube and becomes closed, the wear state of the gas injection nozzle is managed by detecting a change in the gas flow rate or gas pressure supplied to the gas injection nozzle. Method for controlling wear of a gas injection nozzle for a molten metal furnace.