JPH03285007A - Method for injecting gas into tundish - Google Patents

Abstract

PURPOSE:To uniformize flow of molten steel, to accelerate float-up of non-metallic inclusion and also to uniformize temp. and components by blowing inert gas into the molten steel from injecting fine holes arranged at tip part of pipes embedded into a tundish weir. CONSTITUTION:The inert gas introducing pipes 18 communicated with the outer part are embedded into the inner part of tundish weir 10 for continuous casting. The inert gas injecting fine holes 21 are arranged at tip part 19 in this pipe 18. The inert gas is blown to lower position of flow of the molten steel 25 from the fine holes 21 and widely distributed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a weir plate (hereinafter simply referred to as a "weir") provided inside a tundish of a continuous casting facility for molten steel, and particularly relates to a weir plate (hereinafter simply referred to as "weir") that is used to control inert gas from molten steel. This relates to a method for uniformly blowing into the air.

[Prior art 1 A tundish for continuous casting distributes molten steel from a ladle to a continuous casting mold, and also causes the molten steel to flow and floats and separates nonmetallic inclusions such as slag and deoxidation products in the molten steel. This is a container for uniformizing the temperature and composition of molten steel.

To facilitate these functions, conventionally, multilayer or perforated weirs have been used, and inert gas has been blown into the bottom of the tundish using a plug or lance.

Fig. 11 is a cross-sectional view showing the tundish and its peripheral equipment in continuous casting equipment. Flow rate control device) The hill is a chute nozzle that communicates with the lower part, 5 is a long air seal vibe, and 5 is a tanditshu.

7 is a tundish cover; 8 is a lining brick on the side wall of the tundish; 9 is the bottom of the tundish; 1O is a plate-shaped weir installed between both inner walls on the long side of the tundish; it is a passageway for molten steel; A certain through hole 11 is opened in the thickness direction of the weir.

There are 3 to 4 through holes on the top and bottom to promote the flow of molten steel.
In some cases, steps are provided, and in other cases, the through holes are provided not horizontally but at an angle of 60° to 70° in order to direct the flow of molten steel upward.

A long stopper 12 and a slide valve device for restricting the flow rate of molten steel are attached to the spout at the bottom of the tundish, and an immersion nozzle 14 for injecting molten steel into the mold 13 is connected to the lower part thereof.

15 is a hole for injecting molten steel into the mold 13.

In addition, the weir of the tanditshu is not a single wall that connects the tanditshu cover 7 and the bottom part 9 of the tanditshu as described above (it is divided into upper and lower parts and is staggered to improve the flow of molten steel and eliminate inclusions). There is a double weir structure designed to promote floating.

In the conventional tundish mentioned above, inert gas or air is blown from the bottom of the tundish in order to promote its function.

FIG. 12 is a longitudinal sectional view showing gas blowing by a plug, and in the same figure, reference numeral 16 is a gas blowing plug provided on the tundish bottom 9.

Figure 13 is a longitudinal sectional view showing gas blowing using a lance.
17 is a lance for blowing gas.

Note that illustrated arrows in FIGS. 12 and 13 indicate the flow of molten steel.

[Problems to be Solved by the Invention] In the conventional gas injection method as described above, a plug or lance is set for gas injection in the tundish separately from the weir, molten steel pouring hole, and air seal pipe. There is a need for a place or space for this purpose, but there is not enough room, especially in a small tandish.

Furthermore, conventionally, 5
Since this is a gas blowing method using a thin tube with a diameter of 0 to 100 mm, the molten steel surface rises due to the local floating pressure of the gas, causing so-called local molten steel level fluctuations, resulting in insufficient uniformity of the temperature and composition of the molten steel. There was a problem that.

This invention was made to solve these problems, and in particular, it is possible to uniformly stir molten steel even in a small tundish, equalize the temperature and composition of molten steel, and effectively float and separate non-metallic inclusions. The purpose is to obtain a method for blowing gas that can be carried out.

[Means for Solving the Problems] A method for blowing gas into a tundish according to the present invention is to embed a gas introducing vibrator communicating with the outside of the tundish in a forward direction, and inject the gas into the molten steel from the tip of the pipe. This is a method of blowing inert gas, and the tip of the pipe is located below the flow of molten steel, such as below the weir, below the through hole of the weir, or above the footwear, and the tip is wide. This method blows gas through a large number of distributed pores.

[Function] In this invention, the gas is blown upward over the entire lower surface of the flow of molten steel in the tundish, so that the molten steel is uniformly stirred by the wide dispersion of the gas bubbles.

[Embodiment] FIG. 1 is a front view of a weir showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. 1.

In these figures, lO is the through hole of the weir provided in a staggered manner over five stages of upper and lower stages, and these through holes 10 are as follows:
The diameter is 60 mm, the interval is 120 mm, and it is inclined at 65 degrees with respect to the horizontal direction, and serves as a passage for the flow of molten steel.

Reference numeral 18 denotes a stainless steel gas introduction pipe with a diameter of 9 mm embedded inside the weir, communicating with the outside at its upper part and connected to a gas supply device (not shown).

19 is the tip of the gas introduction vibrator 18, which extends horizontally in the length direction of the weir at a position 70 mm from the lower end of the weir, and 20' indicates a large number of gas inlet pipes communicating with this lower end in a right angle direction. The blowing tube is 2.0 mm in diameter in the example.

Figure 3 is an enlarged sectional view of the lower end of Figure 2.

21 is a gas blowing hole communicating with the gas blowing thin tube 20. Fig. 4 is a partially enlarged view of Fig. 3, and 22 is a nylon wire with a diameter of 0.8 mm that was inserted from the gas blowing capillary to the outside of the weir during construction of the weir in order to form gas blowing pores. After curing, the gas is extracted to form gas blowing pores, and 23 is a gas discharge port.

FIG. 5 is a perspective view illustrating the gas blowing mechanism of the above embodiment, where 24 is the long side wall of the tundish, 25 is the molten steel surface, and the molten steel passes through the through hole 11 in the right direction from the indicated pressure. It's in flux.

The gas supplied to the gas introduction vibrator 18 flows horizontally at the tip 19, and in a direction perpendicular to this (thickness direction of the weir).
15 gas blowing tubes on one side and 20 gas blowing tubes on both sides connected to
o. Gas is discharged into the molten steel from the gas discharge port 23 through the gas discharge hole 21. That is, the discharged gas is passed through the through hole 11.
The molten steel flows from below into fine bubbles that are uniformly dispersed over a wide area and rise up.

6 and 7 are a front view and a sectional view of a weir showing another embodiment in which gas is blown from the lower end of the weir,
A porous brick 26 is connected to the tip 19 and installed along the lower end side of the weir, and this porous brick allows gas to be widely discharged into the molten steel through open pores having a pore diameter of 20 to 1100 u. In addition, this porous brick 26
can also be installed on both sides of the weir in the thickness direction.

Figures 8 and 9 show yet another embodiment in which the horizontal tip 19 of the gas introduction vibrator is installed not only at the lower end of the weir (but also at the lower side of each of the multi-stage through holes). These are communicated with gas discharge ports 23 bored at the bottom of each through hole, and the gas is blown out from the bottom of each through hole, that is, from the bottom of each molten steel passage.

No. 10rA shows an embodiment in the case of multiple weirs, and the figure is a vertical cross-sectional view of the weir in the longitudinal direction of the tanditsu, 27 is the lower weir, and 28 is the lower weir. The gas introduction pipe tip portion 19 extends above each lower weir 27 and is connected to the gas blowing thin tube 20 to discharge gas upward from the bottom of the molten steel passage. In this case as well, a large number of gas discharge ports 23 are provided along the upper surface of each lower weir 27, so that the gas can be dispersed over the entire surface of the flow of molten steel.

[Effects of the Invention] As explained above, the present invention embeds the gas introduction vibrator and its tip inside the weir, provides a large number of gas discharge ports in the weir itself, provides a gas blowing function, and blows the gas into the molten steel. Since gas bubbles are uniformly dispersed by blowing up from below over the entire surface of the flow, there is no need for a separate place or space for gas blowing, and it can be applied to small tundishes, and the flow of molten steel is uniform. This has the effect of promoting the floating of non-metallic inclusions, improving the uniformity of the temperature of the molten steel and the composition of the molten steel, and ultimately improving the quality of the steel.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is an enlarged view of the lower part of FIG.
4 is a partially enlarged view of FIG. 3, FIG. 5 is a perspective view illustrating the gas blowout Ia structure of the above embodiment, FIGS. 6 and 7 are front views and sectional views showing other embodiments, 8 and 9 are a front view and a sectional view showing still another embodiment, FIG. 10 is a sectional view showing an embodiment in a multiple weir, and FIG.
FIG. 1 is a sectional view showing a tundish and its peripheral equipment, and FIGS. 12 and 13 are sectional views showing a conventional gas blowing method. In each figure, dan...Tandish weir, 1o...Tandish weir, 11...through hole, 18...gas introduction vibrator, 19
- Gas introduction vibrator tip, 20- Gas blowing thin tube, 2 1... Gas blowing pore, 23- Gas discharge port, 26- Porous brick, 27... Lower layer, 28...・ Lower dam.

Claims (1)

[Scope of Claims] 1. A gas introduction pipe communicating with the outside is buried inside the tundish weir for continuous casting, and molten steel is discharged from gas blowing pores widely distributed at the tip of the pipe and below the flow of molten steel. A method for blowing gas into a tundish, which is characterized by blowing an inert gas into the tundish. 2. The method for blowing gas into a tundish according to claim 1, wherein the inert gas is blown out from a pore provided at the bottom of the weir. 3. The method for blowing gas into a tundish according to claim 1, wherein the inert gas is blown out from a pore provided below the through hole of the weir. 4. The method for blowing gas into a tundish according to claim 1, wherein the inert gas is blown out from a pore provided above the lower dam.