JP2015120955A - Immersion tube for degassing treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersion tube for a degassing treatment device having a long service life.SOLUTION: Provided is a stud comprising: the fine first stud 6 fixed to the upper part of the immersion tube; and the thick second stud 7 fixed to the lower part of the immersion tube. The thick second stud 7 is strong to erosion because of its thickness, exists as a stud, continues to hold unshaped refractories, and has a long service life. Further, since the first stud 6 is fine, it is economical.

Description

  The present invention relates to a dip tube for a degassing apparatus that is used in a degassing apparatus that performs vacuum degassing of molten steel in a steelmaking process and is immersed in molten steel.

  The vacuum degassing process is a process in which decarburization, dehydrogenation, denitrogenation, and the like are further performed from the molten steel that has undergone primary refining.

  The apparatus of the RH method is mainly composed of a vacuum tank having an exhaust port, a pair of dip tubes provided in the lower part thereof, and a ladle for containing molten steel. In the RH method, the vacuum chamber is decompressed and an inert gas is blown from a gas blowing port provided on one side of the dip tube. As a result, the molten steel is sucked into the ladle through the dip tube and degassed in the vacuum chamber. As described above, the RH method is a treatment method in which molten steel is circulated between a ladle and a vacuum tank to perform degassing.

  The apparatus of the DH method is mainly composed of a vacuum chamber, a single dip tube and a ladle provided therebelow. In the DH method, the vacuum chamber is depressurized while molten steel is immersed in a dip tube. Thus, the molten steel is sucked up from the ladle through the dip tube and degassed in the vacuum chamber. As described above, the DH method is a treatment method in which molten steel is relatively raised and lowered between the ladle and the vacuum chamber to perform degassing.

  In general, the dip tube used in the vacuum degassing apparatus is mainly composed of a metal-made tubular cored bar such as steel, and a refractory layer coated on the inside and outside thereof. ing. As the refractory, a standard refractory with better corrosion resistance is used inside the core metal through which molten steel passes, and an irregular refractory that is easy to repair by spraying refractory material is used outside the core metal. Often.

  As a method for supporting such a refractory layer, there is a L-shaped cross-section receiving bracket provided at the lower end of the core metal for a standard refractory, and V-shaped, Y-type, etc. It is common for studs to be implanted in the cored bar.

JP 2008-127777 A

  Since the dip tube is immersed in an extremely high temperature molten steel of 1600 to 1700 ° C., the lower part of the core metal becomes hot at the lower part, and it expands thermally. In general, the coefficient of thermal expansion of a metal cored bar is much larger than that of a refractory. For this reason, the refractory is cracked or peeled by being pressed by the thermally expanding cored bar. Moreover, in the fixed brick which comprises a fixed refractory layer, an opening arises in a joint. Furthermore, since the core metal is softened at a high temperature, it is deformed so that the lower part opens outward by the load of the refractory and the buoyancy received from the molten steel. Such deformation of the metal core also causes further cracking and peeling of the refractory and joint opening of the fixed brick.

  Once the refractory cracks and peels, and the joints of the standard bricks are opened, chemical erosion due to the reaction between the molten steel and molten slag and the refractory, and physical erosion due to the molten steel flowing further progress. It will be easy. Moreover, in the dip tube, heating and cooling are continuously repeated in the required time of 20 to 60 minutes, so that cracking of the refractory further proceeds. And when molten steel penetrate | invades from the crack between extended cracks, joints, etc., a metal core and a stud may melt down, and also a refractory layer may fall out.

  Moreover, even when there is no penetration of molten steel, deterioration of the core metal and stud due to heat reception, particularly deterioration of the stud surface layer occurs, and spurs the stud melting at the time of penetration of the molten steel.

  This invention is made | formed in view of this situation, and makes it a subject to provide the dip tube for degassing processing apparatuses with a long service life which is hard to produce the crack of a refractory.

  The degassing tube for a degassing apparatus according to the present invention covers a tubular cored bar, a plurality of studs attached to the outer peripheral surface of the cored bar, the outer peripheral surface of the cored bar, and is attached to the outer peripheral surface of the cored bar. In a degassing apparatus dip tube comprising: an irregular refractory material supported by the core metal via the stud, and a fixed refractory material fixedly held on an inner peripheral surface of the core metal, the stud Has a thin first stud fixed above the dip tube and a thick second stud fixed below the dip tube.

  According to the above configuration, since the thick second stud is provided in the lower part of the dip tube where the temperature is high and the erosion is likely to occur, the dip tube is strong against the erosion. On the other hand, since the thin first stud is provided in the upper part of the dip tube where the melting loss is relatively low and the amorphous refractory is highly retained.

  Moreover, it is preferable that the outer diameter of the first stud of the dip tube for the degassing apparatus is 5 to 8 mm, and the outer diameter of the second stud is 8 to 13 mm.

  The thicker the stud, the stronger it is against melting. However, the fixed holding property with respect to the irregular refractory is deteriorated. According to the above configuration, the outer diameter of the stud satisfies durability and economy.

  Furthermore, it is preferable that the stud of the dip tube for the degassing apparatus is provided with a third stud that is thinner than the second stud and thicker than the first stud in the middle of the dip tube.

  In this case, there are a thin first stud, a third stud having a middle thickness, and a thick second stud so as to be gradually resistant to melting. That is, the middle third stud is more resistant to melting than the upper first stud, and further, the lower second stud is more resistant to melting than the middle third stud.

  Furthermore, the first stud of the dip tube for the degassing apparatus has an outer diameter of 5 to 7 mm, the second stud has an outer diameter of 9 to 13 mm, and the third stud has an outer diameter of 7 to 9 mm. It is preferable that

  According to the above configuration, the outer diameter of the stud satisfies durability and economy.

  The dip tube for a degassing apparatus of the present invention has a thin first stud fixed above the dip tube and a thick second stud fixed below the dip tube. The thick second stud is stronger than the thin first stud even if the molten steel enters due to a crack of the refractory or the like, and remains as a stud. That is, the second stud continues to hold the irregular refractory. Therefore, the dip tube for the degassing apparatus has a holding effect that the amorphous refractory does not peel off for a longer time, and the service life is extended. Moreover, since the first stud is thin, it is economical.

  Furthermore, the dip tube for a degassing apparatus of the present invention has a third stud that is thinner than the second stud and thicker than the first stud in the middle of the dip pipe for the degassing apparatus. As described above, the thick second stud continues as a stud even when molten steel enters due to cracking of the refractory, etc., and retains the irregular refractory as compared with the thin first stud. Furthermore, since the third stud is located above the dip tube for the degassing apparatus with respect to the second stud, erosion due to molten steel is less likely to occur than the second stud, and the stud can be made thinner than the third stud. . In addition, since the third stud is located below the dip pipe for the degassing apparatus from the first stud, erosion due to molten steel is more likely to occur than the first stud, and by making the stud thicker than the first stud, Even if molten steel invades due to cracks or the like of the object, it can continue as a stud and can continue to hold the irregular refractory. As described above, in the vertical direction of the dip tube for the degassing treatment device, the thickness of the stud is increased stepwise in accordance with the ease of erosion caused by molten steel, so that the amorphous refractory does not peel longer. Has a holding effect. Here, it goes without saying that the thicker one of the studs is more resistant to melting, but by using a thin stud at the upper part of the dip tube for the degassing apparatus, there is an advantage from an economical point of view. Fulfill. That is, the dip tube for the degassing apparatus has a holding effect that the amorphous refractory does not peel off while satisfying the economical efficiency, and the service life is extended.

1 is a simplified cross-sectional view of a dip tube for a degassing apparatus showing a first embodiment of the present invention. It is a simplified sectional view of a dip tube for a degassing apparatus showing a second embodiment of the present invention. The

  A first embodiment of a dip tube for a degassing apparatus according to the present invention will be described with reference to FIG. The dip tube for a degassing apparatus includes a tubular core metal 1, a fixed refractory 2 that covers the inner peripheral surface of the core metal 1, and an atypical refractory 3 that covers the outer peripheral surface of the core metal 1. Yes. Here, the cored bar 1 is made of steel and has a substantially circular cross-sectional shape. Moreover, the metal core 1 is provided with a flange which is a portion protruding from the cylindrical shape above the metal core 1. Furthermore, the cored bar 1 is provided with a supporting part for supporting the fixed refractory 2 inside the cylinder so as not to fall under its own weight. On the other hand, the fixed refractory 2 is made of magnesia-chromium. The indeterminate refractory 3 is made of alumina. Further, the gap between the core metal 1 and the fixed refractory 2 is fixed by a mortar 10. As shown in FIG. 1, the upper side of the degassing apparatus dip tube is a thin first stud 6, and the lower side of the degassing apparatus dip pipe is a thick second stud 7. The shape of these studs is V-shaped as shown in FIG. These studs are obtained by processing a pipe material and have a substantially circular cross section.

  In the present embodiment, the thickness of the first stud 6 is 6 mm, and the thickness of the second stud 7 is 9 mm. At this time, the service life of the dip tube for the degassing apparatus was 80 ch. For comparison, the thickness of all studs was 6 mm. In this case, the service life of the dip tube for the degassing apparatus was 50 ch. That is, by having the thick second stud fixed below the thin first stud, the service life of the dip tube for the degassing apparatus is dramatically improved. Here, “ch” represents the number of ladles, that is, the number of charges until the dip tube for the degassing apparatus can no longer withstand.

  A second embodiment of the dip tube for the degassing apparatus of the present invention will be described with reference to FIG. The dip tube for a degassing apparatus includes a tubular core metal 1, a fixed refractory 2 that covers the inner peripheral surface of the core metal 1, and an atypical refractory 3 that covers the outer peripheral surface of the core metal 1. Yes. Here, the cored bar 1 is made of steel and has a substantially circular cross-sectional shape. Furthermore, the core metal 1 includes a flange that is a portion protruding from the cylindrical shape above the core metal 1. Moreover, the cored bar 1 is provided with a support part for supporting the fixed refractory 2 inside the cylinder so as not to fall under its own weight. On the other hand, the fixed refractory 2 is made of magnesia-chromium. Furthermore, the amorphous refractory 3 is made of alumina. Further, the gap between the core metal 1 and the fixed refractory 2 is fixed by a mortar 10. As shown in FIG. 2, the upper portion of the degassing treatment device dip tube is a thin first stud 6, and the lower portion of the degassing treatment device dip tube is a thick second stud 7, the middle of the degassing treatment device dip tube. A third stud 8 is provided. The shape of these studs is V-shaped as shown in FIG. These studs are obtained by processing a pipe material and have a substantially circular cross section.

  The material of the metal core 1 may be a metal such as an alloy other than steel. Furthermore, the cross-sectional shape of the core metal 1 may be an ellipse other than a substantially circular shape.

  In addition to magnesia-chromium, the standard refractory 2 is made of magnesia-carbon, alumina-chromium, alumina-carbon, alumina-magnesia, alumina-magnesia-carbon, alumina-spinel-carbon. Etc.

  Furthermore, the material of the amorphous refractory 3 may be spinel, alumina-silica, alumina-spinel, alumina-magnesia, etc. in addition to alumina. Further, the irregular refractory material may be a so-called regular brick joined with fire-resistant mortar or the like and joined with open joints.

  The stud shape may be T-shaped, Y-shaped or the like in addition to the V-shaped. That is, anything other than the pipe material can be used as long as it is a rod-shaped material. Furthermore, the cross-sectional shape of the stud may be either an ellipse or a polygon other than a substantially circular shape.

DESCRIPTION OF SYMBOLS 1 Core metal 2 Standard refractory 3 Non-standard refractory 6 First stud 7 Second stud 8 Third stud 9 Distribution channel 10 Mortar

Claims (4)

A tubular core,
A plurality of studs attached to the outer peripheral surface of the core;
Covering the outer peripheral surface of the cored bar, and an indeterminate refractory supported by the cored bar through the stud attached to the outer peripheral surface of the cored bar,
In the dip tube for a degassing apparatus comprising a fixed refractory fixed and held on the inner peripheral surface of the core metal,
The dip tube for a degassing apparatus, wherein the stud has a thin first stud fixed above the dip tube and a thick second stud fixed below the dip tube.   The dip tube for a degassing apparatus according to claim 1, wherein the first stud has an outer diameter of 5 to 8 mm, and the second stud has an outer diameter of 8 to 13 mm.   2. The dip tube for a degassing apparatus according to claim 1, wherein the stud has a third stud thinner than the second stud and thicker than the first stud in the middle of the dip tube.   The degassing apparatus according to claim 3, wherein the first stud has an outer diameter of 5 to 7 mm, the second stud has an outer diameter of 9 to 13 mm, and the third stud has an outer diameter of 7 to 9 mm. Dip tube.

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