JP2013231219A - Immersed pipe of vacuum degassing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersed pipe of a vacuum degassing apparatus favorable for suppressing a tendency that a core opens in the radially outer direction due to the influence of thermal expansion and the like and suppressing the occurrence of a crack in a refractory layer, during the use of the immersed pipe.SOLUTION: An immersed pipe 1 includes a core 2 and a cylindrical refractory layer 3 arranged on the inner circumference side of the core 2, the outer circumference side of the core 2, and the lower side of the core 2 so as to form a longitudinal molten metal passage 30. The core 2 has a buried stud 5 buried under the lower part of the refractory layer 3. The buried stud 5 is directed in the radially inner direction of the core 2 and fixed to the core 2 so as to protrude towards the molten metal passage 30. The buried stud 5 has a bar member 50 fixed to the core 2 in the inner circumference side of the core 2 so as to protrude towards the molten metal passage 30 and an engaging part 53 which is formed at the tip part of the bar member 50 and engaged with the refractory layer 3.

Description

  The present invention relates to a dip tube of a vacuum degassing apparatus.

  Conventionally, a dip tube used in a vacuum degassing apparatus has been provided (Patent Document 1). This dip tube is a refractory layer coated on the core metal so as to form a cylindrical core metal around the central axis along the vertical direction and a vertical molten metal passage passing through the central axis. And.

  During use, the dip tube is exposed to high temperatures because high-temperature molten metal passes through the molten metal passage. Furthermore, since the dip tube receives heat from the molten metal below the dip tube, the dip tube is also exposed to a high temperature in this sense. For this reason, the lower end portion of the cored bar of the dip tube tends to open outwardly due to the influence of thermal expansion or the like. As a result, the refractory layer covering the core metal may be cracked.

JP 2005-226092 A

  The present invention has been made in view of the above-described circumstances, and suppresses the tendency of the cored bar to open in the radially outward direction due to the effects of thermal expansion and the like, thereby suppressing the occurrence of cracks in the refractory layer. It is an object of the present invention to provide a dip tube for a vacuum degassing apparatus that is advantageous for extending the life of a layer.

  The present invention is a dip tube used in a vacuum degassing apparatus, wherein (i) a cylindrical cored bar that is wound around a central axis along the longitudinal direction, and (ii) a vertical pipe that passes through the central axis. A cylindrical refractory layer disposed on the inner peripheral side of the cored bar forming the molten metal passage in the direction, the outer peripheral side of the cored bar, and the lower side of the cored bar, (iii) A buried stud which is oriented in the radial direction of the core metal and is fixed to the core metal so as to protrude toward the molten metal passage and which is embedded in a lower part of the refractory layer and engages with the refractory layer. It is characterized by having. The buried stud is engaged with the refractory layer formed at the tip of the rod-shaped member and the rod-shaped member fixed to the core metal in the radial direction of the core metal so as to protrude toward the molten metal passage. Having a part is preferred.

  The buried stud has a rod-shaped member and an engaging portion. The engaging portion preferably has a V shape, a U shape, or a T shape. For this reason, even when the lower part of the metal core is about to open to the outer peripheral side, the embedded stud exhibits resistance because the engaging portion of the embedded stud is engaged with the refractory layer. Therefore, the problem that the lower part of the cored bar tries to open in the radially outward direction due to the influence of thermal expansion or the like is suppressed.

  Furthermore, it is preferable that a coating mortar layer is laminated on at least a part of the surface of the cored bar. The coated mortar layer is sandwiched between the cored bar and the refractory layer. The coating mortar layer is composed of mortar that is formed on the surface of the core metal by applying a trowel, brush, spray, or the like. The coating mortar layer is formed by a forming means different from that of the refractory layer, and is directly formed on the surface of the cored bar. For this reason, heat or cracks transmitted through the refractory during use are also transmitted to the cored bar through the coated mortar layer, and damage to the cored bar is suppressed accordingly. The coated mortar layer may be formed on the surface of the stud.

  The coated mortar layer preferably contains heat-resistant reinforcing fibers. That is, the coated mortar layer is preferably a high-strength layer reinforced with fibers. Thereby, the function which the crack which arose in the refractory stops at an application mortar layer becomes high. The coated mortar layer is preferably a heat insulating mortar. That is, it is preferable that the coated mortar layer has higher heat insulation than a refractory formed by castable.

  Furthermore, the thickness of the coated mortar layer is preferably thinner than the thickness of the cored bar. If the thickness of the coating mortar layer can be reduced, the thickness of the core metal or the refractory layer is ensured. Even if the coated mortar layer is formed on at least a part of the surface of the cored bar, the coated mortar layer suppresses damage such as a temperature rise in the part of the cored bar formed. The portion of the core bar where the temperature rise is most likely to be damaged is a portion embedded in the lower portion of the dip tube immersed in the molten metal. Therefore, the coated mortar layer is preferably formed on at least the lower part of the surface of the cored bar.

When the coating mortar layer is 100% by mass, the coating mortar layer preferably contains 1 to 30% of heat-resistant reinforcing fibers. Examples of heat-resistant reinforcing fibers include artificial mineral fibers, natural mineral fibers, and synthetic fibers. Artificial mineral fibers are those obtained by melting glass, rocks, etc. into fibers, and mainly include glass wool, rock wool, slag wool, and long glass fibers. Rock wool is one that uses rock as the main raw material and has good heat resistance. Slag wool is made from slag. The long glass fiber has a straight cylindrical shape and a diameter of 3 to 20 micrometers. Natural mineral fibers are naturally occurring fibrous minerals, and mainly include wollastonite, sepiolite, attapulgite and the like. Wollastonite is a silicon-oxygen chain (SiO ₃ ) with an infinite basic structure, and calcium cations are connected to this long chain. This is called wollastonite (calcium silicate), and is mainly composed of SiO ₂ and CaO. As an ingredient. Wollastonite has a needle shape, is cleaved, has excellent heat resistance, and has a low coefficient of thermal expansion. Sepiolite is magnesium silicate and has fine pores. Attapulgite is basically a magnesium silicate with magnesium replaced by aluminum or iron. Attapulgite has a hollow needle shape and good heat resistance.

  The coated mortar layer is advantageous for suppressing damage such as a red heat state of the cored bar and extending the life of the cored bar and thus extending the life of the dip tube or the lower tank. That is, the coated mortar layer covered with the cored bar can separate the refractory layer and the cored bar, suppress deterioration of the cored bar, increase the durability of the cored bar, and protect the cored bar. For this reason, the selection range of the material for the refractory layer is widened. For example, the material for the refractory layer can be prioritized over the refractory material having high corrosion resistance over the refractory material having high heat insulation.

  According to the present invention, when the dip tube is used, the embedded stud having the engaging portion can function as a resistor when the core metal tends to open radially outward due to the influence of thermal expansion or the like. As a result, at the time of using the dip tube, it is advantageous to suppress the tendency of the core bar to open outwardly due to the influence of thermal expansion or the like, and to suppress the occurrence of cracks in the refractory layer. As a result, the life of the refractory layer can be extended.

1 is a cross-sectional view of a dip tube according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a dip tube according to the second embodiment. FIG. 10 is a cross-sectional view of a dip tube according to the third embodiment. FIG. 10 is a cross-sectional view of a dip tube according to the fourth embodiment. FIG. 10 is a cross-sectional view of a dip tube according to the fifth embodiment. FIG. 10 is a cross-sectional view of a dip tube according to the sixth embodiment. It is sectional drawing of the vacuum degassing apparatus which concerns on an application form and the dip tube was mounted. It is sectional drawing of a dip tube in connection with a comparative example.

(Embodiment 1)
FIG. 1 shows the concept of the first embodiment. FIG. 1 shows only the right half of the central axis 1p, and the left half of the central axis 1p is omitted, but is symmetrical with respect to the central axis 1p. This embodiment is applied to a dip tube 1 used in a vacuum degassing apparatus. The dip tube 1 includes a cored bar 2 having a cylindrical shape that extends around a central axis 1p along the vertical direction, and a refractory layer 3 that forms a vertical molten metal passage 30 that passes through the central axis 1p. ing.

  The refractory layer 3 has a cylindrical shape, and the inner peripheral side of the cored bar 2, the outer peripheral side of the cored bar 2, and the cored bar 2 of the cored bar 2 so as to form a vertically oriented molten metal passage 30 passing through the central axis 1p. Located on the lower side. The core metal 2 has a cylindrical inner core metal 20 and a cylindrical outer metal core 22 that are coaxial with each other, and a ring shape that fixes the inner metal core 20 and the upper ends of the outer metal core 22 by welding or bolt fastening. A fixed flange portion 24 formed, and an arm-shaped or flange-shaped support portion 26 projecting radially inwardly on the inner metal core 20 of the metal core 2 so as to support the lower portion of the regular brick layer 31 are provided. The support portion 26 is positioned above the lower end 20d of the inner cored bar 20.

  As shown in FIG. 1, the cored bar 2 is formed of a metal (for example, carbon steel or alloy steel). The core metal 2 functions as a core body of the refractory layer 3. Further, when the dip tube 1 is used (at the time of vacuum degassing treatment), the molten metal passage 30 side is decompressed. For this reason, the cored bar 2 made of metal that is continuous in the circumferential direction has an outside air blocking property, and has an intake air suppressing function that suppresses the intake of outside air existing on the outer peripheral side of the dip tube into the molten metal passage 30 side. Have.

  Accordingly, the refractory layer 3 includes a regular brick layer 31 disposed in a cylindrical shape on the inner peripheral side of the inner core metal 20, an outer refractory layer 32 disposed on the outer peripheral side of the outer core metal 22, and the inner core metal. 20 and a bottom refractory layer 33 disposed on the lower side of the outer cored bar 22. The bottom refractory layer 33 has a lower surface 33d.

  As can be understood from FIG. 1, the inner peripheral portion 31 i of the shaped brick layer 31 and the inner peripheral portion 33 i of the bottom refractory layer 33 form a molten metal passage 30 through which a high-temperature molten metal (for example, molten steel) passes. The outer refractory layer 32 is a castable layer in which a castable material having fluidity is poured and dried and solidified. The bottom-side refractory layer 33 is a castable layer in which a castable material having fluidity is poured and dried and solidified. The second castable layer 320 is also loaded between the inner core bar 20 and the outer core bar 22. The third castable layer 330 is also loaded between the inner peripheral surface of the inner metal core 20 and the outer peripheral surface of the refractory brick layer 31.

  As shown in FIG. 1, the cored bar 2 has a Y-shaped embedded stud 5. The buried stud 5 is buried under the bottom refractory layer 33 of the refractory layer 3. The embedded stud 5 is fixed to the lower part of the outer metal core 22 of the metal core 2 by welding or bolt fastening so as to be directed in the inner radial direction (arrow D direction) of the metal core 2 and to protrude toward the molten metal passage 30. And embedded in the refractory portion so as to engage with the refractory portion of the bottom refractory layer 33.

  Specifically, as shown in FIG. 1, the embedded stud 5 is made of metal (for example, carbon steel or alloy steel) and includes a rod-shaped member 50 and an engaging portion 53. The rod-shaped member 50 is fixed to the lower portion 22d of the outer core metal 22 so as to be directed inwardly in the radial direction (arrow D direction) of the cylindrical core metal 2 and to protrude toward the molten metal passage 30. . The engaging portion 53 has engaging elements 53a and 53c so as to form a V shape or a U shape formed at the tip end portion (end portion facing in the radial direction) of the rod-shaped member 50. Since the rod-like member 50 has a predetermined length, the engaging portion 53 of the embedded stud 5 can be separated from the inner peripheral portion of the cored bar 2 toward the inner diameter direction, and the engaging portion 53 can be separated from the bottom refractory layer. It is possible to approach the inner peripheral portion 33 i of 33.

  FIG. 1 shows a longitudinal section cut in a direction along the central axis 1p. In FIG. 1, the engaging elements 53a and 53c are visually recognized. The rod-shaped member 50 extends along the horizontal direction. Since the engaging part 53 engages with the bottom refractory layer 33, even if the cored bar 2 tries to spread in the radially outward direction (arrow F direction), the spread can be suppressed.

  As shown in FIG. 1, a plurality of second engaging portions 57 made of V studs are fixed by welding or the like over substantially the entire outer peripheral portion of the outer metal core 22 of the metal core 2. The second engaging portion 57 is embedded in the outer refractory layer 32 and suppresses its falling off. A plurality of the embedded studs 5 are arranged on the inner peripheral side of the cored bar 2 at intervals in the circumferential direction so as to make one round around the central axis 1p.

  As described above, according to the present embodiment, the embedded stud 5 has a Y shape and is oriented in the inner radial direction (arrow D direction) of the cored bar 2 and protrudes toward the molten metal passage 30. A rod-like member 50 fixed to the lower part of the outer cored bar 22 of the gold 2 and an engagement portion 53 having a V shape or a U shape formed at the tip end portion (end portion facing inward in the radial direction) of the rod-like member 50. Have. The rod-shaped member 50 has a predetermined length and extends along the horizontal direction. The engaging portion 53 engages with the refractory portion 33x existing on the inner peripheral side of the core metal 2 in the bottom refractory layer 33, and functions as a resistor. For this reason, even if the cored bar 2 tries to spread in the radially outward direction (the direction of the arrow F shown in FIG. 1), the spread can be suppressed. When the dip tube 1 is used, the tendency of the cored bar 2 to open in the radially outward direction (the direction of arrow F shown in FIG. 1) due to the influence of thermal expansion or the like is suppressed. Therefore, it is advantageous to suppress the occurrence of cracks in the refractory layer 3, particularly the bottom refractory layer 33. The engaging portion 53 is not limited to a V shape or a U shape, and may be a T shape.

(Dimension example)
As shown in FIG. 1, the height dimension of the dip tube 1 is A. Let B be the height dimension of the regular brick layer 31. Let C be the shortest distance dimension from the inner periphery of the cored bar 2 to which the embedded stud 5 is fixed to the inner periphery 31 i of the shaped brick layer 31. Let E be the shortest distance from the rod-like member 50 of the buried stud 5 to the lower surface 33d of the bottom refractory layer 33 of the refractory layer 3. Further, the shortest distance dimension from the tip 53e of the engaging portion 53 of the buried stud 5 to the inner peripheral portion 33i of the bottom refractory layer 33 is LB, and the length of the buried stud 5 is LA.

  When this inventor experimented in each steelworks, in order to suppress the crack in the bottom side refractory layer 33 of the refractory layer 3, generally, E is preferable to ensure 50 millimeters or more. When the shortest distance dimension (LA + LB) from the inner peripheral portion of the core metal 2 that fixes the embedded stud 5 to the inner peripheral portion 33i of the bottom refractory layer 33 is 100, the length of LA, that is, the embedded stud 5 The length is 40-80, more preferably 50-70. The length of LB is 60 to 20, more preferably 50 to 30. Furthermore, when LB / C was less than 0.2, cracks were easily formed in the refractory layer 3. When LB / C was 0.2 to 0.6, particularly 0.3 to 0.5, cracks were hardly formed in the refractory layer 3.

  FIG. 8 shows a comparative example of basically the same size as in the first embodiment. According to the comparative example shown in FIG. 8, since the embedded stud according to the present invention is not embedded in the bottom refractory layer 33, the lower end of the core metal 2 opens in the radially outward direction (arrow F direction). Due to the deformation, cracks MA often occur in the refractory layer.

(Embodiment 2)
FIG. 2 shows the concept of the second embodiment. This embodiment basically has the same configuration and the same function and effect as the first embodiment. A plurality of second engaging portions 57 formed of V studs are fixed to almost the entire outer peripheral portion of the outer cored bar 22 constituting the cored bar 2. Further, a third engagement portion 58 is fixed to the lower part of the outer core metal 22 constituting the core metal 2. The third engaging portions 58 are fixed at intervals along the circumferential direction of the cored bar 2. Further, as shown in FIG. 2, the third engaging portion 58 formed of a V-shaped (or U-shaped) stud is fixed downward to the lower portion 22 d of the outer metal core 22, and the refractory layer 3. Are embedded in the outer refractory layer 32 or the bottom refractory layer 33. In addition, the third engaging portion 58 is fixed at an interval in the circumferential direction around the central axis 1 p at the lower portion of the outer cored bar 22. The end of the rod-shaped member 50 of the embedded stud 5 is connected to the third engagement portion 58 by welding or bolt fastening.

  The embedded stud 5 (length: LA) is directed to the inner diameter direction (arrow D direction) of the core metal 2 and protrudes toward the molten metal passage 30, and the tip of the rod member 50 (inward diameter direction). And an engagement portion 53 having a V shape or a U shape formed at an end portion facing the surface. A plurality of the buried studs 5 are arranged at intervals (for example, within a range of 10 to 45 °) in the circumferential direction so as to make one round around the central axis 1p.

  According to the present embodiment, the buried stud 5 is fixed to the lower part of the outer cored bar 22 via the lower third engaging portion 58, so that the bottom refractory layer 33 extends from the lower end 22 d of the outer cored bar 22. The buried stud 5 can reinforce the bottom refractory layer 33 while ensuring the thickness Ta of the bottom refractory layer 33 up to the lower surface 33d of the bottom.

(Embodiment 3)
FIG. 3 shows the concept of the third embodiment. This embodiment basically has the same configuration and the same function and effect as the first embodiment. A buried stud 5 is fixed to the lower part of the inner core bar 20 by welding or bolt fastening. The embedded stud 5 is fixed to the lower portion 20d of the inner core metal 20 so as to be directed inwardly in the radial direction (arrow D direction) of the core metal 2 and to protrude along the horizontal direction toward the molten metal passage 30. And an engaging portion 53 having a V shape or a U shape formed at the tip end portion (the end portion facing in the radially inward direction) of the rod-shaped member 50. A plurality of the buried studs 5 are arranged at intervals (for example, within a range of 10 to 45 °) in the circumferential direction so as to make one round around the central axis 1p.

(Embodiment 4)
FIG. 4 shows the concept of the fourth embodiment. This embodiment is different from Embodiment 1 described above in that the cored bar 2 has a single structure. However, basically, this embodiment has the same function and effect as the first embodiment. Since the cored bar 2 has a single structure, the structure of the cored bar becomes simple.

  An embedded stud 5 is fixed to the lower part 2d of the core metal 2 by welding or the like. The embedded stud 5 is directed to the inner diameter direction (arrow D direction) of the core metal 2 and is fixed to the lower part of the core metal 2 so as to protrude along the horizontal direction toward the molten metal passage 30. And a first engagement portion 53 having a V shape or a U shape formed at the distal end portion (the end portion radially inward) of the first rod-shaped member 50.

  As shown in FIG. 4, the first engaging portion 53 is engaged with a castable layer that constitutes the bottom refractory layer 33.

  A plurality of the buried studs 5 are arranged at intervals (for example, within a range of 10 to 45 °) in the circumferential direction so as to make one round around the central axis 1p.

(Embodiment 5)
FIG. 5 shows the concept of the fifth embodiment. This embodiment is different from the fourth embodiment in that the coating mortar layer 6 is formed on the surfaces of the core metal 2 and the studs 5 and 57.

  The coating mortar layer 6 is composed of mortar that is formed on the surface of the core bar by applying it with a trowel, brush, spray, or the like. The coating mortar layer 6 is formed by a forming means different from the refractory layer 3 and is directly formed on the surface of the cored bar 2. For this reason, heat or cracks transmitted through the refractory layer 3 during use are also transmitted to the cored bar 2 through the coated mortar layer 6, and damage to the cored bar 2 is suppressed accordingly. The same can be said for the studs 5 and 57, and heat or cracks transmitted through the refractory layer 3 during use are also transmitted to the studs 5 and 57 through the coated mortar layer 6, and the studs. Damage of 5, 57 is suppressed.

(Embodiment 6)
FIG. 6 shows the concept of the sixth embodiment. This embodiment basically has the same configuration and the same function and effect as the first embodiment. The cored bar 2 has a single structure. A first embedded stud 5F is fixed to the lower part 2d of the core metal 2 by welding or the like. The first embedded stud 5F is fixed to the lower part of the metal core 2 so as to be directed in the radial direction (arrow D direction) of the metal core 2 and to protrude along the horizontal direction toward the molten metal passage 30. It has a rod-shaped member 50F and a first engagement portion 53F having a V shape or a U shape formed at the tip end portion (the end portion facing in the radially inward direction) of the first rod-shaped member 50F.

  As shown in FIG. 6, the first engaging portion 53 </ b> F is engaged with the castable layer that forms the bottom refractory layer 33. The second embedded stud 5S is located below the first embedded stud 5F. The first embedded stud 5F and the second embedded stud 5S are arranged as two upper and lower stages in the height direction. The second embedded stud 5S is a second rod shape that is fixed to the lower portion of the core metal 2 so as to be directed in the radial direction (arrow D direction) of the core metal 2 and to protrude along the horizontal direction toward the molten metal passage 30. It has a member 50S and a second engaging portion 53S having a V shape or a U shape formed at the tip end portion (end portion facing in the radial direction) of the second rod-like member 50S. The second engaging portion 53 </ b> S is engaged with the castable layer constituting the bottom refractory layer 33. Since the second rod-shaped member 50S has a bent portion 500 bent at an angle θ and has a vertical portion 501 and a horizontal portion 502, it can contribute to ensuring the thickness of the bottom refractory layer 33. .

  A plurality of first embedded studs 5F and second embedded studs 5S are arranged at intervals (for example, within a range of 10 to 45 °) in the circumferential direction so as to make one round around the central axis 1p. A plurality of the first embedded stud 5F and the second embedded stud 5S are arranged at intervals in the circumferential direction so as to make one round around the central axis 1p. The circumferential phase of the two embedded studs 5S may be the same phase or a different phase.

(Application form)
FIG. 7 shows an application form. As shown in this figure, the vacuum degassing apparatus is a reflux type, and includes an upper tank 100 that is depressurized to a high vacuum state, a lower tank 110, and a pair of dip tubes 1R and 1L. During operation, the dip tubes 1R and 1L are set in the ladle. In this state, the molten metal 230 (molten steel) of the ladle 200 as a container ascends the molten metal passage 30 of one dip pipe 1L (rising pipe) and descends the molten metal path 30 of the other dip pipe 1R (down pipe). Then, the molten metal 230 is refluxed so as to return to the ladle 200. Thus, degassing of the molten metal in the ladle 200 proceeds by refluxing the molten metal in the ladle 200 through the dip tubes 1R and 1L. The gas discharged from the molten metal is discharged in the direction of arrow W.

  (Others) The present invention is not limited to the embodiment described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist.

  1 is a dip tube, 1p is a central axis, 2 is a core, 20 is an inner core, 22 is an outer core, 3 is a refractory layer, 30 is a molten metal passage, 31 is a shaped brick layer, and 32 is an outer refractory layer , 33 is a bottom refractory layer, 5 is a buried stud, 50 is a rod-shaped member, 53 is an engaging portion, 58 is a third engaging portion, and 6 is a coating mortar layer.

Claims (2)

A dip tube used in a vacuum degassing apparatus, wherein the cored bar forms a cylindrical cored bar around a central axis along a vertical direction and a vertical molten metal passage passing through the central axis A cylindrical refractory layer disposed on the inner peripheral side, the outer peripheral side of the cored bar, and the lower side of the cored bar,
The cored bar is fixed to the cored bar so as to be directed in the radial direction of the cored bar and protrude toward the molten metal passage, and embedded in a lower part of the refractory layer, A dip tube for a vacuum degassing apparatus, characterized by having an embedded stud to be engaged.   The embedded stud is formed with a rod-shaped member fixed to the core metal in a radially inward direction of the core metal so as to protrude toward the molten metal passage, and a refractory layer formed at a tip portion of the rod-shaped member. The dip tube of the vacuum degassing apparatus according to claim 1, further comprising an engaging portion having a V shape or a U shape to be engaged.

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