JPH02432Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a lance pipe that is immersed in molten metal and injects inert gas, and in particular a lance pipe discharge port in which a porous brick is fitted horizontally in the gas discharge part. Regarding the improvement of

Prior Art As is well known, in the steel industry, for example, impurities in molten steel are quickly floated to the surface and removed in order to obtain clean molten steel with few non-metallic inclusions, or additives such as deoxidizers are used in ladles. To promote this process, inert gas is blown into the molten steel from the bottom of the ladle or from the tip of the lance pipe, and the energy that causes the inert gas to rise is absorbed. The molten steel is stirred by

As shown in the longitudinal cross-sectional side view in Fig. 2, the conventionally used lance pipe for stirring molten steel has a round steel core pipe (hereinafter abbreviated as core pipe) 1 for gas introduction with a closed end and a required length. The outer periphery and bottom of the proximal end (large diameter) side, which communicates with the core tube 1 and is formed into a truncated conical shape, is surrounded by an iron plate case 2 in a direction substantially perpendicular to the tip, and a gas supply pipe 3 is connected to the bottom. The provided porous brick 4 is disposed, and the core tube 1 and the porous brick 4 are
The outer periphery of the refractory is lined with a monolithic refractory 5 such as high alumina castable. For example, when this lance pipe is immersed in molten steel in a ladle and inert gas is discharged from the tip (small diameter side) of the porous brick 4, the inert gas discharged into the molten steel becomes fine bubbles and a small amount of inert gas is discharged into the molten steel. This allows bubbling treatment with a high stirring effect to be achieved using active gas.

Problems to be solved by the invention However, the service life of the lance pipe is limited by peeling due to the thermal gradient of the porous bricks 4, not by the monolithic refractories 5, or by the iron plate case surrounding the proximal outer periphery and bottom of the porous bricks 4. Vertical cracks occur in the monolithic refractories 5 due to the thermal expansion of the porous bricks 4 and the monolithic refractories 5 due to the vertical cracks, and this is determined by the degree of damage around the porous bricks 4, such as separation between the porous bricks 4 and the monolithic refractories 5. Furthermore, even if the degree of damage such as peeling, vertical cracking, or skin separation in the 4 parts of the porous bricks is slight, the gas supply pipe 3 connecting the porous bricks 4 to the core pipe 1 is
A length of ~50m/m is required. Therefore, the length of porous brick 4 can only be increased to a maximum of 100 m/m compared to the shape of the lance pipe, and even if porous brick 4, which has excellent spalling resistance, is used, it will cause wear and tear. The speed was 4.0 to 4.5 mm/charge, and the minimum effective length of the porous brick 4 was about 50 to 60 m/m, so only about 9 to 12 charges could be used.

In addition, the effect of thermal expansion of the iron plate case 2 surrounding the proximal outer periphery and bottom of the porous brick 4 is large, and not only skin separation occurs, but also a gap between the porous brick 4 and the monolithic refractory 5. ,
Molten steel enters through this gap and melts the steel plate case 2, causing the porous bricks 4 to often fall off, resulting in a short life.

Means for Solving the Problems The present invention was made with the aim of solving these problems, and it is possible to extend the length of the porous bricks by arranging the porous bricks below the core tube. The purpose of the present invention is to provide a lance pipe discharge port that can significantly improve the service life.

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in FIG. 1, and parts common to those in FIG. 2 are denoted by the same reference numerals.

The discharge port of the lance pipe according to the present invention has a length comparable to the lower end radius of the lance pipe in which a porous brick 4 is fitted horizontally in the gas discharge part, as shown in the longitudinal side view in Fig. 1. A porous brick 4 having a size of 4 is disposed below the core tube 1, and the lower end of the core tube 1 and the proximal end of the porous brick 4 are connected by a gas flow curved tube 6.

The porous brick 4 has the diameter dimension at least on the tip (small diameter) side the same as the conventional one in order to equalize the discharge area of the inert gas, and the length dimension further extends from the lower end radius of the lance pipe to the outer radius of the core pipe 1. After setting the dimensions within the added range and manufacturing a predetermined truncated conical shape, the outer periphery and bottom of the proximal end (large diameter) side are surrounded by an iron plate case 2.

The height of the iron plate case 2 that surrounds the outer periphery of the porous bricks 4 needs to be large enough to securely hold the porous bricks 4, and is generally about 2/5 or more of the length of the porous bricks 4. However, if a gap is created between the porous brick 4 and the monolithic refractory 5 due to the difference in thermal expansion between the steel plate case 2 and the porous brick 4, molten steel may enter and melt the steel plate case 2. Therefore, it is desirable to keep the length to the minimum necessary, and to make it about 1/3 to 1/2 of the length of the porous brick 4. and,
An air chamber 7 is provided between the iron plate case 2 surrounding the proximal end surface and the bottom of the porous brick 4 in order to uniformly disperse the inert gas, but the iron plate case 2 is extended to the tip of the porous brick 4. Sometimes it is surrounded by In addition, as a method of surrounding the porous bricks 4 with the iron plate case 2, there is a method by shrink fitting, and the height of the iron plate case 2 surrounding the outside,
There are no restrictions on the structure and surrounding method of the air chamber 7.

Then, the porous brick 4 whose outer periphery and bottom part are surrounded by the iron plate case 2 is placed below the tip (lower end) side of the core tube 1 of the required length with the tip closed in a direction perpendicular to the extension line of the core tube 1. The lower end of the core tube 1 and the proximal end of the porous brick 4 are connected by means such as screwing or welding using a gas flow bent tube 6, and the core tube 1 and the gas A monolithic refractory material 5 such as high alumina castable is poured into the outer periphery of a porous brick 4 whose outer periphery and bottom are surrounded by a flow curved pipe 6 and an iron plate case 2, and is lined in a predetermined shape.

Function The lance pipe of the present invention configured as described above is
For example, when the tip end is immersed in molten steel in a ladle and inert gas is blown into it, the inert gas passes from the lower end of the core tube 1 into the gas flow bent tube 6 and is uniformly dispersed in the air chamber 7. It enters the pores of the porous brick 4, and the discharge port 8
The bubbles are discharged into the molten steel to form fine bubbles, and a bubbling process with a high stirring effect can be performed using a small amount of inert gas.By placing the porous brick 4 below the core pipe 1, the outer diameter of the lance pipe can be The length of the porous brick 4 can be increased without changing the dimensions.
By locating the iron plate case 2 surrounding the porous bricks 4 at the axis of the lance pipe where the temperature is least likely to rise, vertical cracks in the monolithic refractory 5 caused by thermal expansion of the iron plate case 2 and the porous bricks 4 can be prevented. Factors that inhibit life extension, such as separation of the monolithic refractories 5, can be reduced.

Example The porous brick 4 was manufactured into a truncated cone shape of 40〓 to 60〓 x 160 m/m, and the base end side outer periphery (height 55 m/m) and bottom part were surrounded by the iron plate case 2. , are arranged laterally below a core tube 1 having an outer diameter of 48.6〓m/m, and after connecting the lower end of the core tube 1 and the proximal end of the porous brick 4 with a gas flow curved tube 6, these By pouring high alumina castable monolithic refractory 5 around the outer periphery of the lance pipe and lining it, a lance pipe of the present invention having an outer diameter of 300 m/m at the lower end was obtained.

As a comparative example, porous brick 4 is 40〓~55〓×
It has a truncated cone shape of 100 m/m, and the outer periphery (height 40 m/m) and the bottom are surrounded by an iron plate case 2 with a gas supply pipe 3. m/m) are connected perpendicularly to the lower ends of these parts, and then a high alumina castable monolithic refractory material 5 is poured around these outer peripheries and lined with a conventional structure with an outer diameter of 300〓m/m. I prepared a lance pipe. Then, using the lance pipe of this invention and the lance pipe of conventional structure,
An actual furnace test was conducted by immersing the steel in molten steel in a ladle and blowing inert gas at a rate of 40 minutes.

As a result, the lance pipe with the conventional structure was greatly affected by the thermal expansion of the steel plate case 2, causing vertical cracks in the monolithic refractory 5 and skin separation between the monolithic refractory 5 and the porous bricks 4, resulting in 8 However, the lance pipe of this invention sustained only minor damage around the porous bricks 4 and could be used continuously up to 14 times.

Effects of the invention As explained above, according to the invention, the porous brick is arranged below the core tube, and the lower end of the core tube and the proximal end of the porous brick are connected by a gas flow curved pipe. The effective length of the porous brick can be increased without changing the outside diameter of the pipe, and even if the wear rate of the porous brick is the same as before, the service life can be significantly extended to 1.5 to 1.8 times that of the conventional one. It can prolong life. In addition, damage to the area around the porous bricks caused by thermal expansion of the iron plate case surrounding the outer periphery and bottom of the porous bricks is reduced.
By being able to prevent the intrusion of molten steel, the accidents of porous bricks falling off are reduced, which reduces the chance of short-lived bricks, resulting in significant practical effects such as significant cost reductions.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional side view showing an embodiment of the present invention;
Figure 2 is a vertical cross-sectional side view of a conventional lance pipe, and the symbols in the figure are as follows. 1... Core pipe, 2... Steel plate case, 3... Gas supply pipe, 4... Porous brick, 5... Monolithic refractory, 6... Gas distribution curved pipe, 7... Air chamber, 8... Outlet.

Claims (1)

[Scope of utility model registration request] In a lance pipe in which a porous brick 4 is fitted horizontally in the gas discharge part, a porous brick 4 having a length dimension comparable to the lower end radius of the lance pipe is arranged below the core pipe 1, and the porous brick 4 is disposed below the core pipe 1. A discharge port of a lance pipe characterized in that a lower end portion and a base end side of a porous brick 4 are connected by a gas flow curved pipe 6.