JPH05748U - Large amount of gas injection dip tube - Google Patents

Abstract

(57) [Abstract] [Purpose] When arranging a large number of tuyere bricks on the dip tube of a vacuum degassing furnace, a means to reduce the life of the dip tube due to wear of the tuyere surface, heat spalling, etc. To find out. [Structure] A plurality of tuyere bricks having gas injection holes are formed on the peripheral wall surface, leaving a portion for forming a downward flow of molten steel, and no gas injection holes are provided in either the circumferential direction or the vertical direction. By installing at least one buffer brick in multiple stages with intervening spaces, it is possible to inject the maximum amount of inert gas, and the mutual expansion of melting loss due to the back attack of the tuyere brick blowing gas and the gas Thermal spalling during blowing can be minimized. Also, since there is little interference of the inert gas emitted from each tuyere, there is little coalescence of the inert gas, and when the gas floats, it makes good contact with the molten steel, and bubbles can be formed on a large area on the surface of the molten steel, so the decarburization reaction Be promoted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an immersion pipe in a vacuum degassing furnace capable of rapid decarburization of molten steel, and more particularly to an arrangement of gas injection tuyere opening on the inner wall of such an immersion pipe.

[0002]

[Prior Art]

 For example, as disclosed in Japanese Patent Application Laid-Open No. 61-130415, Japanese Patent Application Laid-Open No. 2-200721, Japanese Patent Application Laid-Open No. 2-213410, etc., a submerged pipe portion which is immersed in molten steel in a ladle to raise the molten steel. A tuyere is placed on the soaked tube, and an inert gas is blown from the tuyere into the molten steel that rises in the dip tube to increase the vacuum exposure area and increase the refining effect of degassing and decarburizing the molten steel. Degassing furnaces are known.

[0003]

[Problems to be solved by the device]

 In order to improve the refining efficiency such as decarburization by injecting an inert gas from the immersion pipe into this vacuum degassing furnace, a large amount of an inert gas is blown into the molten steel rising in the immersion pipe. It is necessary to form a large amount of foaming active surface on the surface.

Moreover, in order to form a large amount of foaming active surface on the surface of the ascending molten steel in the dip tube, the diameter of the blowing tuyere is reduced to reduce the size of bubbles blown into the molten steel, and It is necessary to blow a large amount of inert gas, and for that purpose, it is necessary to arrange a large number of small tuyere pipes. Furthermore, in order to form a rising and falling circulating flow in the dip tube using a single dip tube, the pipe opening to the inner wall of the dip tube must be formed on one side of the inner wall of the dip tube. Also has the limitation of.

As described above, when a large number of tuyere pipes are arranged concentratedly in a limited area of the inner peripheral wall of the dip tube, the tuyere brick surface is worn due to the rebound of the blown gas brick surface. The so-called back attack promotes the wear of the tuyere surface due to the mutual influence of the wear of the brick.In addition, the concentrated arrangement of many tuyere pipes increases the cooling by the blown gas and increases the temperature inside the brick. There is a problem that heat spalling occurs due to the difference, which shortens the life of the immersion tube.

The problem to be solved in the present invention is to provide a large number of tuyere pipes in the immersion pipe in a vacuum degassing furnace having a large diameter immersion pipe and forming a circulating flow of molten steel in the immersion pipe. The purpose is to find means for reducing the wear of the tuyere surface and the reduction in the life of the immersion pipe due to heat spalling.

[0007]

[Means for Solving the Problems]

 The dipping pipe of the present invention is provided with a plurality of tuyere bricks having gas blowing holes on the peripheral wall surface, which leaves the portion forming the downward flow, and gas blowing holes in both the circumferential direction and the vertical direction. The feature is that at least one buffer brick that does not have is installed in multiple stages with the bricks interposed therebetween.

In FIG. 1 showing the inner surface shape of the tuyere brick, the short side length b of the tuyere brick 8 and the outer peripheral length a of the tuyere pipe 9 embedded substantially at the center of the tuyere brick 8 are shown. In FIG. 2 where the ratio b / a is approximately 3 or more and the tuyere bricks 8 are arranged, the ratio L / b between the adjacent tuyere distances L and the tuyere width b in the dip tube circumferential direction is shown. Is preferably 2 or more in order to reduce the melting loss of tuyere brick.

[0009]

[Action]

 Injecting maximum inert gas by arranging multiple tuyere bricks with gas injection holes and at least one buffer brick without gas injection holes in multiple stages on the peripheral wall. In addition, mutual expansion of melting loss due to back attack of blown gas of tuyere brick and heat spalling at the time of blowing gas can be minimized.

Since the interference of the inert gas emitted from each tuyere is small, the coalescence of the inert gas is also small, the gas is in good contact with the molten steel when it floats, and bubbles are formed on a large area on the surface of the molten steel to decarburize. The reaction is accelerated.

FIG. 3 shows the ratio b / a of the short side length b of the inner surface of the tuyere brick to the outer peripheral length a of the tuyere pipe embedded approximately at the center of the tuyere brick and the melting rate of the tuyere brick. FIG. 3 is a diagram showing the relationship, where there is an inflection point of the erosion rate at a location where the b / a ratio is approximately 3, and the erosion rate is rapid when the b / a ratio is greater than approximately 3. Reduce to.

Further, FIG. 4 shows the relationship between the ratio L / b of the distance L between the tuyere in the circumferential direction of the immersion pipe and the tuyere brick width b and the melting rate, and the ratio of L / b is approximately There is an inflection point of the erosion rate at location 2, and the erosion rate decreases rapidly when the L / b ratio is large from about 2 to a large value.

[0013]

【Example】

 FIG. 5 is a vertical cross-sectional view showing the structure of the immersion tube of the vacuum degassing furnace to which the present invention is applied. FIG. 6 is a plan sectional view showing an arrangement state of tuyere bricks of the dipping tube.

In FIG. 5, a vacuum degassing furnace 10 includes a dip tube 1 having a diameter of 1000 mm or more for dipping in molten steel in a ladle (not shown), and a vacuum tube having a larger diameter than the dip tube 1. It consists of tank 2. Reference numeral 3 denotes an iron shell that defines the outer shape of the vacuum chamber, and this iron shell 3 is continuous with the core material 4 of the dip tube 1. In the dipping tube 1, the inner surface of the core material 4 is formed by a magro type brick 5, and the outer surface side thereof is formed by an irregular refractory material 6. Reference numeral 7 denotes an inert gas supply pipe for supplying the inert gas to the tuyere pipe 9 in the tuyere brick 8. The tuyere bricks 8 have the form shown in FIG. 1, are arranged in two stages on one side of the dip tube 1, and further, as shown in FIG. Within the area, every other ordinary brick 5 is placed as a buffer brick. This region forms the region of the molten steel upflow R in FIG. 5, and the region in which the tuyere bricks 8 are not arranged forms the region of the molten steel downflow D.

FIG. 7 is an internal development view showing the arrangement state of the tuyere bricks of the immersion pipe. The tuyere brick 8 having the tuyere pipe 9 is a buffer brick made of ordinary bricks 5 It is formed in two stages in the direction perpendicular to the circumferential direction.

FIG. 8 shows an example in which tuyere bricks 8 are arranged in a circumferential direction of the dipping tube in three stages with three buffer bricks 5 in the circumferential direction.

Since the immersion pipe 1 of the present embodiment has the above-described structure, as shown in FIG. 3, a ladle (not shown) is placed in the molten steel that has been raised in the immersion pipe 1 by the vacuum in the immersion pipe 1. Inert gas from the porous plug provided at the bottom of the dipping pipe is blown into the side of the dipping tube 1 where the tuyere brick 8 is installed, and the tuyere pipe 9 of the tuyere brick 8 is provided in several stages. By introducing a large amount of gas by adding these inert gases, a thick activated bubble layer BL is formed on the surface of the molten steel, and an ascending flow R and a descending flow D of molten steel are preferably formed in the immersion pipe 1, The degassing and the decarburization treatment are preferably performed.

[0018]

[Effect of the device]

 The present invention has the following effects.

(1) A large amount of inert gas can be blown uniformly and into the molten steel that has risen in the immersion pipe, and the decarburization and degassing reactions are promoted.

(2) Despite the fact that a large amount of inert gas can be blown in, the rate of melting damage of the lining brick can be reduced.

(3) A clear upward flow and a downward flow can be formed in the immersion pipe.

(4) Therefore, the refining effect of the vacuum degassing furnace can be enhanced, and the life of the furnace can be increased.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the relationship between the size of a tuyere pipe formed on a tuyere brick used in the present invention, a brick, and the melting loss of the brick.

FIG. 2 is a diagram for explaining a relationship between an array of tuyere bricks used in the present invention and melting loss of the bricks.

FIG. 3 is a diagram showing the relationship between the size of a tuyere pipe and a brick, and the melting rate of the brick.

FIG. 4 is a diagram showing a relationship between an array of tuyere bricks and a melting rate of bricks.

FIG. 5 is a vertical cross-sectional view showing an example of the structure of a dip tube of a vacuum degassing furnace to which the present invention is applied.

FIG. 6 is a plan cross-sectional view showing an example of an arrangement state of tuyere bricks of the dipping tube.

FIG. 7 is an inner surface development view showing an example of an arrangement state of tuyere bricks of an immersion pipe.

FIG. 8 is an inner surface development view showing another arrangement state of tuyere bricks of the dipping tube.

[Explanation of symbols]

 1 Immersion pipe 2 Vacuum tank 3 Iron skin 4 Core material 5 Brick 6 Amorphous refractory 7 Gas supply pipe 8 Tuyere brick 9 Tuyere pipe 10 Vacuum degassing furnace R Upflow D Downflow BL Activated bubble layer

Claims (1)

[Claims for utility model registration] [Claim 1] A plurality of tuyere bricks having gas injection holes are provided on the circumferential wall surface, leaving the part forming the downward flow, in either the circumferential direction or the vertical direction. A large amount gas-immersed dipping pipe in which at least one buffer brick having no gas-blowing holes is installed in multiple stages with interposing therebetween.