JPH07256415A - Tundish upper nozzle - Google Patents

Abstract

PURPOSE:To more effectively spout supplied gas into molten steel flow by preventing gas leakage from occurring between a porous refractory and an iron shell, in the tundish upper nozzle. CONSTITUTION:In the tundish upper nozzle having a gas blowing function, the outer periphery of the main body is surrounded with the iron shell 2a, and upper and lower porous refractories 1a, 1b are freely set to the gas blowing position in the inner part of the main body. Respective outer peripheral surfaces of the refractories 1a, 1b are covered with the iron shell through gas pools arranged independently and directly connected to each gas introducing pipe and the part between the outer peripheral part and the iron shell 2a is closely filled with castable refractories 4. By this method, the gas leakage at the time of operation can effectively be prevented and then, the introduced gas is efficiently spouted into a nozzle hole and as a result, the lowering of the back pressure in the upper nozzle during operation is prevented. Further, since inclusion of Al2O3, etc., can effectively be removed, the development of the nozzle clogging can effectively be prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a tundish upper nozzle for use in a tundish for continuous casting of steel.

[0002]

2. Description of the Related Art In continuous casting, when a molten metal is poured into a mold from a tundish, gas bubbling by an upper nozzle has been widely practiced as a measure for preventing nozzle clogging due to precipitation of inclusions such as Al ₂ O ₃ . In order to effectively prevent such blockage of the nozzles, at the present time, the two-stage type upper nozzles are widely used for blowing gas. This allows gas to be blown from a position closer to the throttle of the sliding plate, and the amount of gas blown can be adjusted up and down independently.
Gas bubbling can be performed very effectively.

[0003]

However, even in the upper nozzle having the above structure, the gas cannot be effectively blown out unless the gas leak is completely prevented, and the prevention of the nozzle clogging is limited. Further, in the conventional integrally molded product of the porous body and the non-porous body, it is impossible to directly connect the gas introduction pipe to the upper porous portion, and it is difficult to discharge the gas uniformly and efficiently. It was

The present invention was devised in view of the above-mentioned conventional techniques, and prevents gas leakage between the porous refractory material and the iron shell, and provides the supplied gas more effectively in the molten steel flow. Is what you are trying to do.

[0005]

In the gas seal structure according to the prior art, gas leakage is prevented by filling a slight gap between the iron shell and the outer circumference of the main body with mortar. But,
The mortar contracted and deformed due to heat history during actual use, and a gap was created between the iron shell and the refractory, which was a factor of gas leakage. In order to solve these problems, the present invention is to solve the above problems, that is, the outer peripheral portion of the main body is surrounded by a steel shell, and the upper and lower porous refractory materials are freely installed inside the main body, and the gas supply elements are directly connected to each other. The tundish upper nozzle is characterized in that its outer peripheral portion is densely filled with a refractory castable.

[0006]

[Structure and operation] The gas leak of the structure in which the mortar is filled between the porous refractory and the iron shell as described above is caused by the fact that the mortar becomes a dense state as described above. It is considered that there is a problem in the structure itself, in which the mortar must be filled between the side surface of the porous refractory material and the steel skin. On the other hand, in the present invention, the porous refractory is formed into a ring shape and attached to the iron skin, a sufficient space is provided between the side surface and the iron skin, and the outer peripheral portion thereof is densely filled with the refractory castable. By
It is not necessary to fill the space between the porous refractory material and the iron shell with mortar, and the gas introduction pipe can be directly connected to the porous body, so that structural gas leakage can be effectively prevented.

[0007]

EXAMPLES Specific examples of the present invention will be described below. FIG. 1 shows an embodiment of a tundish upper nozzle according to the present invention, 1a and 1b are porous refractory materials, 2a is an outer peripheral iron skin, 2b is an inner surface iron skin, 3 is a gas introduction pipe, 4 is a refractory castable, 5 has shown the gas pool. As shown in the drawing, the outer peripheral portion of the nozzle body is surrounded by the iron shell 2a, and the outer peripheral portions of both the upper and lower porous refractories 1a and 1b attached to the iron shell 2a are filled with the refractory castables 4. , And both of these porous refractories 1a,
Gas introduction pipes 3 are directly connected to 1b. It is a so-called two-stage upper nozzle, and the gas injection amount can be adjusted up and down independently according to the situation of the molten steel flow in the mold.

In this embodiment, the gas inlet pipe 3 is directly connected to the porous refractory materials 1a and 1b at both upper and lower parts of the nozzle body through the gas pool 5 by the covered iron shell 2b. Therefore, the gas is effectively discharged from the porous refractory material. An upper nozzle having such a structure was compared with a conventional example having a structure in which a mortar was filled between the porous refractory material and the iron shell. The test method investigated the change in back pressure due to heating of the upper nozzle. In this case, heating was performed with a gas burner, and the temperature inside the nozzle hole was raised to 1600 ° C. while maintaining an air pressure of 3.0 l / min and maintained for 3 hours. Table 1 shows changes with time in the back pressure of the upper nozzle. As is apparent from this, according to this example, the back pressure of the upper nozzle is not decreased, and the gas leak can be effectively prevented. I understand.

[0009]

[Table 1]

Needless to say, the tundish upper nozzle according to the present invention can be applied to either an extrapolation type or an interpolating type.

[0011]

As described above, according to the tundish upper nozzle of the present invention, the gas leak during actual use can be effectively prevented, and therefore the introduced gas is effectively discharged into the nozzle hole. As a result, the back pressure of the upper nozzle during use does not drop, and inclusions such as Al ₂ O ₃ can be effectively removed, and nozzle clogging can be effectively prevented. Is highly available.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a tundish upper nozzle according to the present invention.

FIG. 2 is a cross-sectional view showing a tundish upper nozzle which is an integrally molded product of a porous body and a non-porous body of a conventional example.

[Explanation of symbols]

 1a, 1b Porous refractory 2,2a Outer iron crust 2b Inner iron crust 3 Gas inlet pipe 4 Fire resistant castable 5 Gas pool 6 Non-porous refractory 7 Mortar

Claims (1)

[Claims] In a tundish upper nozzle that has a gas blowing function, the outer periphery of the main body is surrounded by a steel shell, and both upper and lower porous refractory materials are freely installed on the gas blowing inner hole surface, and the outer peripheral surface is A tundish upper nozzle characterized by having a structure in which it is independently covered with a steel shell via a gas pool that directly communicates with a gas introduction pipe, and is surrounded by castable dense refractory material inside the steel shell on the outer periphery of the main body.