JP2014037584A - Lower tank in rh vacuum degasification equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deformation of a circulation tube of a lower tank to a truncated chevron shape by suppressing nonuniform dilation of a base plate of the lower tank and the circulation tube caused by radiant heat from molten steel in a ladle.SOLUTION: A circulation tube 11 installed in a basilar part of a lower tank 1 of RH vacuum degasification equipment is made a cylindrical body shape having a diameter smaller than a diameter of the lower tank 1. A pair of immersion tubes 3 of two of molten steel ascent use and molten steel descent use are installed in a basilar part of the cylindrical body shaped circulation tube 11. A lining refractory 11d of a bond part 11c of the circulation tube 11 with the immersion tubes 3 is made to be divided by an isometric degree from a center of a cross section of the bond part 11c with the immersion tube 3. In the lining refractory 11d, inside parts 11a adjacent to each other of the bond part 11c with two immersion tubes 3 are made an integrated type structure without a horizontal joint, and outside parts 11b are made an upper and lower two-step structure. A heat receiving area of a base plate of the lower tank becomes small, thereby nonuniform dilation of a base plate and the circulation tube and deformation of the circulation tube to truncated chevron shape caused by radiant heat from ladle molten steel can be suppressed.

Description

  The present invention relates to a lower tank in an RH vacuum degassing facility, and particularly to a structure of a reflux pipe installed at the bottom of the lower tank.

  While the molten steel stays in the lower tank of the RH vacuum degassing facility, as shown in FIG. 5, the iron shell at the bottom of the lower tank 1 (hereinafter referred to as a bottom plate and denoted by reference numeral 1a). The two recirculation pipes 2 which attach the immersion pipe 3 immersed in the molten steel in a ladle are installed like a leg.

  As shown in FIG. 6, the lower tank 1 of such an RH vacuum degassing facility has an adjacent portion of two reflux pipes 2 and two reflux flows by radiant heat from the molten steel in the ladle at the time of molten steel treatment. The temperature of the bottom plate 1a portion between the tubes 2 rises to a high temperature. On the other hand, the portions of the two reflux tubes 2 located on the outer peripheral side of the bottom plate 1a and the outer peripheral side portion of the bottom plate 1a are not affected by the radiant heat or are not affected by them.

  Accordingly, the bottom plate 1a of the lower tub 1 has a non-uniform thermal expansion at each position, the bottom plate 1a is deformed, and the adjacent portion of the reflux tube 2 is thermally expanded. As a result, the outer periphery of the bottom plate 1a in the reflux tube 2 There is a problem that the portion located on the side opens in the direction indicated by the white arrow and deforms into a square shape.

  As shown in FIG. 7 (a), the brick 2a that is stacked in the vertical direction without gaps on the inner side of the reflux pipe 2 is positioned on the outer peripheral side of the bottom plate 1a in the reflux pipe 2 as a result of such a C-shaped deformation. In the part to be performed, the horizontal joint between the bricks 2a is opened at the position indicated by the white arrow in FIG. Then, the furnace life is shortened due to the influence of steel leakage due to the insertion of the metal into this open joint. In addition, since the bottom plate 1a is deformed due to thermal influence, the replacement frequency of the bottom plate 1a increases.

  As a result, it will affect the operation of the molten steel treatment, so the deformation of the reflux pipe and the bottom plate due to thermal expansion and the prevention of horizontal joint opening of the brick lined inside the reflux pipe are anxious and various proposals have been made. It was made.

  For example, in Patent Document 1, for the purpose of preventing deformation of the bottom plate of the lower tank, as shown in FIG. 8, a ladle is provided at a portion between the reflux pipes 2 of the bottom plate 1 a of the lower tank 1 of the RH vacuum degassing equipment. There has been proposed a technique for installing a heat insulating plate 4 that shields radiant heat from the heat.

  However, in the case of the technique proposed in Patent Document 1, since the heat insulating plate itself is deformed by the radiant heat from the molten steel in the ladle, it is necessary to repair or replace the heat insulating plate. There is a problem that interferes with the processing work. In addition, the influence of radiant heat transmitted to the bottom plate of the lower tank and the adjacent part of the reflux tube through the gap between the heat shield and the reflux tube cannot be ignored, and avoid the deformation of the reflux tube into a C shape. I can't.

  Moreover, in patent document 2, as shown in FIG. 9, the temperature of the baseplate 1a by the radiant heat from the molten steel in a ladle is sprayed on the part between the reflux pipes 2 of the baseplate 1a of the lower tank 1. A technique for preventing deformation of the bottom plate of the lower tank has been proposed to alleviate the non-uniformity of the bottom tank. In addition, 5 in FIG. 9 is a header pipe which supplies the gas body sprayed on the part between the reflux pipes 2 of the bottom plate 1a of the lower tank 1. FIG.

  However, simply spraying a gas body on the bottom plate of the lower tank cannot completely mitigate the uneven expansion of the bottom plate due to the radiant heat from the molten steel in the ladle, and the radiant heat transmitted to the adjacent part of the reflux tube Since there is no influence, it cannot be avoided that the reflux tube is deformed into a C shape.

JP 2010-95766 A Japanese Patent Laid-Open No. 10-287914

  The problem to be solved by the present invention is that the bottom plate deformation prevention technology proposed in Patent Documents 1 and 2 completely eliminates uneven expansion of the bottom plate and the reflux tube due to radiant heat from the molten steel in the ladle. The fact that it cannot be mitigated and the C-shaped deformation of the reflux tube cannot be avoided.

The lower tank in the RH vacuum degassing facility of the present invention is
In order to avoid uneven expansion of the bottom tube of the lower tank and the reflux tube due to radiant heat from the molten steel in the ladle and to prevent the reflux tube from deforming into a C shape,
The reflux pipe installed at the bottom of the lower tank is formed into a cylindrical body having a diameter smaller than the diameter of the lower tank. The main feature is the installation of a set of dip tubes.

In the present invention,
The lining refractory at the joint portion between the cylindrical circulatory pipe and the two dip tubes is divided at an equal angle from the center of the cross section of the joint portion with the dip tube. Of these, it is desirable that the adjacent inner side of the joint portion with the two dip tubes has an integral structure without a horizontal joint and the outer side has a two-stage structure.

  In the present invention, since the two reflux tubes that have been conventionally installed at the bottom of the lower tank are changed to one having a cylindrical shape with a diameter smaller than the diameter of the bottom of the lower tank, the heat receiving of the bottom plate of the lower tank The area becomes smaller. Therefore, the non-uniform expansion of the bottom plate and the reflux pipe due to the radiant heat from the molten steel in the ladle can be suppressed, and the circular pipe can also be prevented from being deformed into a C shape by the radiant heat of the molten steel in the ladle.

  At that time, among the lining refractories of the joint portion between the two dip tubes of the reflux tube having a cylindrical shape, the inner side adjacent to the joint portion with the two dip tubes has an integral structure without a horizontal joint. In this case, the horizontal joint of the part is not opened, and the refractory is not cracked by the metal bar.

It is the perspective view which looked at the lower tank of RH vacuum degassing equipment which has the structure of the present invention from the lower part. It is the figure which looked at the lower tank of RH vacuum degassing equipment which has this invention structure from the side. (A) is the figure which looked at the reflux tube part of FIG. 1 from the lower surface, (b) is the longitudinal cross-sectional view which expands and shows the junction part with the dip tube of a reflux tube. It is the figure which compared the distortion amount which generate | occur | produces in the bottom plate center part of the lower tank of this invention, and the conventional lower tank. It is a figure explaining the conventional structure of the lower tank of RH vacuum degassing equipment. It is a figure explaining the problem of the lower tank of RH vacuum degassing equipment. (A) (b) is a figure explaining the problem at the time of the outer peripheral side part of the baseplate of the lower tank in the reflux tube installed in the lower tank deform | transformed into the C shape. It is a figure explaining the deformation | transformation prevention technique of the lower tank bottom board proposed by patent document 1. FIG. It is a figure explaining the deformation | transformation prevention technique of the lower tank bottom board proposed by patent document 2. FIG.

  The purpose of the present invention is to prevent uneven deformation of the bottom plate of the lower tank and the reflux pipe due to radiant heat from the molten steel in the ladle and to prevent the reflux pipe from being deformed into a letter C shape at the bottom of the lower tank. This was realized by making the reflux tube into a cylindrical shape with a diameter smaller than the diameter of the lower tank.

Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is a perspective view of a lower tank of an RH vacuum degassing facility having the structure of the present invention as viewed from below, FIG. 2 is a view of the same as in FIG. 1, and FIG. It is the longitudinal cross-sectional view of the junction part of the figure seen and the dip tube of a reflux tube.

  Reference numeral 11 denotes a reflux pipe installed at the bottom of the lower tank 1 in the RH vacuum degassing equipment. In the present invention, one cylindrical body having a diameter smaller than the diameter of the lower tank 1 is provided, and the bottom of the lower tank 1 is used. Are installed concentrically, and a pair of dip pipes 3 are installed in a leg shape at the bottom of the reflux pipe 11 for raising the molten steel and lowering the molten steel. In addition, the diameter of the reflux tube 11 should just be the length which is smaller than the diameter of the lower tank 1, and can install the two dip tubes 3. FIG.

  In this invention, the center part of the bottom plate 1a of the lower tank 1 where the influence of the radiant heat from the molten steel in a ladle is large by making the reflux tube 11 into a cylindrical shape having a diameter smaller than the diameter of the lower tank 1 in this way. Is blocked by the reflux tube 11, the influence of the radiant heat on the bottom plate 1a is reduced.

  By the way, as a result of investigating the amount of strain generated in the central part of the bottom plate of the conventional structure and the bottom plate of the structure of the present invention, the inventors have adopted the structure of the present invention as shown in FIG. It was confirmed that the amount of distortion generated at the center of the bottom plate of the lower tank can be suppressed.

  However, the radiant heat from the molten steel in the ladle is transmitted to the coupling portion 11c of the reflux pipe 11 with the two dip pipes 3. In that case, the adjacent inner part 11a (refer FIG. 3 (a)) of the coupling | bond part 11c with the two dip pipes 3 of the reflux pipe 11 has the influence of the radiant heat from molten steel in a ladle compared with the outer part 11b. It becomes the same as the lower tank 1 of a conventional structure that becomes large.

  Accordingly, in the case where the lining refractory 11d of the joint portion 11c of the reflux pipe 11 connected to the two dip pipes 3 is stacked in the vertical direction as in the conventional case, the inner part 11a is the same as the conventional reflux pipe. The iron skin may expand due to thermal expansion.

  In order to prevent the opening of the horizontal joint, in this embodiment, as shown in FIG. 3, the radiant heat from the molten steel in the ladle among the lining refractories 11 d of the joint portion 11 c of the circulating pipe 11 and the dip pipe 3 is used. The inner portion 11a having a large influence is made into an integrated structure without a horizontal joint.

  With such a configuration, even if the influence of the radiant heat from the molten steel in the ladle becomes large, the horizontal joint does not open, so that no metal is inserted into the portion where the horizontal joint is open. In the conventional structure, horizontal joint opening frequently occurred at 100 to 120 heat, but the joint opening suppressing effect equivalent to that of the cylindrical integrated brick was obtained by the structure of the present invention. Further, since the horizontal joint does not open, distortion of the iron skin of the inner portion 11a is also suppressed.

  If the distortion of the coupling portion 11c of the reflux tube 11 with the dip tube 3 is increased, the two dip tubes 3 cannot be mounted in parallel when the dip tube 3 is attached. The leveling of 11c is performed so that the two dip tubes 3 are attached in parallel.

  In the case of the present invention in which the inner portion 11a has an integrated structure without a horizontal joint, the number of leveling operations is as shown in Table 1 below as compared with the conventional structure in which the structure is stacked in the vertical direction. Decreased significantly.

  On the other hand, among the lining refractories 11d of the joint portion 11c of the circulating pipe 11 and the dip pipe 3, the outer part 11b is not greatly affected by the radiant heat from the molten steel in the ladle. It is assumed that there is a horizontal joint 11e as a structure.

  In addition, in this embodiment, the lining refractory material 11d of the coupling portion 11c of the reflux tube 11 and the dip tube 3 is divided at an equal angle from the center of the cross section of the coupling portion 11c of the dip tube 3. ing. Such a structure eliminates the need for special equipment and molds necessary for manufacturing an integral cylindrical refractory, and reduces the cost burden.

  Needless to say, the present invention is not limited to the above-described examples, and the embodiments may be appropriately changed within the scope of the technical idea described in the claims.

  For example, in the above embodiment, in order to prevent deformation due to thermal expansion of the bottom plate and the reflux pipe and to more effectively suppress the C-shaped deformation of the dip pipe installed in the reflux pipe, the diameter of the lower tank is reduced. Among the refractory lining the joint portion between the two dip tubes of the reflux tube in the shape of a small-diameter cylindrical body, the inner side adjacent to the joint portion with the two dip tubes has an integral structure without a horizontal joint. Shows what you did.

  However, the inside of the adjoining joint portion of the refractory lined with the circulator tube only in the shape of a cylindrical body having a diameter smaller than the diameter of the lower tank or the dip tube of the circulator tube is a horizontal joint. Needless to say, even an integrated structure having no structure is effective in preventing deformation due to thermal expansion of the bottom plate and the reflux tube and suppressing the C-shaped deformation of the dip tube installed in the reflux tube.

DESCRIPTION OF SYMBOLS 1 Lower tank 1a Bottom plate 3 Immersion pipe 11 Circulation pipe 11a Inner part 11b Outer part 11c Coupling part 11d Lined refractory 11e Horizontal joint

Claims (3)

A lower tank in an RH vacuum degassing facility,
The reflux pipe installed at the bottom of the lower tank is formed into a cylindrical body having a diameter smaller than the diameter of the lower tank, and two pipes for raising the molten steel and lowering the molten steel are provided at the bottom of the reflux pipe having the cylindrical shape. A lower tank in an RH vacuum degassing facility, characterized in that a set of dip tubes are installed. A lower tank in an RH vacuum degassing facility,
Two lined refractories at the bottom of the lower tub, which are connected to the dip tube of the reflux tube installed in a leg shape, are divided at equal angles from the center of the cross section of the reflux tube. A lower tank in an RH vacuum degassing facility, wherein two adjacent dip tubes have an integrated structure without horizontal joints and an outer structure having two upper and lower stages.   The lining refractory at the joint portion between the cylindrical circulatory pipe and the two dip tubes is divided at an equal angle from the center of the cross section of the joint portion with the dip tube. 2. In the RH vacuum degassing equipment according to claim 1, wherein the adjacent inner side of the coupling portion with the two dip tubes has an integrated structure without a horizontal joint and the outer side has a two-stage structure. Lower tank.

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