JP5848735B2 - Almost circular molten steel container - Google Patents

Description

  The present invention relates to a molten steel container having a substantially oval horizontal cross-sectional shape for containing molten steel.

  The RH type vacuum degassing device used for the production of high-purity steel is composed of a vacuum chamber in which molten steel is accommodated and subjected to vacuum degassing treatment, and a vacuum tank immersed in the molten steel in the ladle and between the vacuum chamber and the ladle. A pair of dip tubes for circulating the molten steel. The vacuum chamber usually has a substantially circular horizontal cross-section, and includes a cylindrical iron skin and a plurality of refractory bricks lined with the iron skin. The refractory bricks are quadrangular columns whose horizontal cross-sectional shapes are substantially isosceles trapezoids, and are arranged in an annular shape along the inner surface of the iron skin.

  In that case, the refractory bricks have the side corresponding to the longer base of the isosceles trapezoid facing the outer side of the substantially circular vacuum chamber (facing the iron shell) and correspond to the shorter base. The side surfaces corresponding to the adjacent refractory bricks and the isosceles trapezoidal legs are brought into contact with each other while facing the inward side of the vacuum chamber, and are arranged along the iron skin (see Patent Document 1). . Therefore, this refractory brick is tapered toward the inner side of the vacuum chamber.

  Further, there is known an RH vacuum degassing apparatus including a vacuum chamber whose horizontal cross-sectional shape is substantially oval (see FIG. 12). If the horizontal cross-sectional shape of the vacuum chamber is substantially oval, the cross-sectional area of the dip tube can be increased, so that the processing efficiency of the vacuum degassing process by the RH vacuum degassing apparatus can be improved. Therefore, the RH type vacuum degassing apparatus including such a vacuum tank whose horizontal cross-sectional shape is substantially oval is suitable for production of high purity steel.

  When the horizontal cross-sectional shape of the vacuum chamber is approximately circular, as described above, the refractory bricks are arranged in an annular shape, but when the horizontal cross-sectional shape of the vacuum chamber is approximately oval, it is annular (arc-shaped). There are a part arranged in a straight line and a part arranged in a straight line. In other words, the iron shell of the vacuum chamber whose horizontal cross-sectional shape is substantially oval is composed of a linear portion that extends linearly and two arc portions that are continuous from both ends of the linear portion, and is therefore lined inside the arc portion. The refractory bricks are arranged in an arc shape along the arc-shaped iron skin as in the case of the vacuum tank having a substantially circular horizontal cross section, but the refractory bricks lined on the inner side of the straight portion. Are arranged in a straight line along a straight iron skin.

  The refractory brick lined on the arc part of the iron skin is a quadrangular column whose horizontal cross-sectional shape forms a substantially isosceles trapezoid, as in the case of a vacuum tank whose horizontal cross-sectional shape is approximately circular. It has a shape with a width that tapers inward. If it is such a shape, since adjacent refractory bricks compete with each other, it is difficult for the refractory bricks to fall off inward of the vacuum chamber. In addition, even if cracks occur in the refractory bricks, and cracks occur in the inner and outer directions, the inner side of the vacuum chamber of the inner part of the refractory bricks due to the competition between the refractory bricks Peeling (spalling) is unlikely to occur.

  On the other hand, the refractory brick lined on the straight part of the iron skin is a rectangular column with a rectangular horizontal cross section, so there is no competition between adjacent refractory bricks, and the refractory brick is a vacuum chamber It is easy to fall out to the inside. Moreover, when a crack etc. generate | occur | produce in a refractory brick and the crack and the division | segmentation of the inside / outside direction arise, the inner side part of a refractory brick tends to peel to the inner side of a vacuum chamber.

Therefore, the refractory bricks lined on the straight part of the iron shell are made into square pillars having a shape as shown in FIG. Techniques for suppressing this have been proposed. That is, the refractory brick of FIG. 13 is a quadrangular prism body having a substantially trapezoidal horizontal cross-sectional shape, and only one of the two side surfaces 100 in contact with the adjacent refractory brick is provided with a slope, It has a shape with a width that tapers toward the inside of the vacuum chamber.
By using the refractory bricks in such a shape, competition between adjacent refractory bricks occurs, so the refractory bricks lined on the straight part of the iron shell fall off to the inside of the vacuum chamber. And spalling can be reduced.

Japanese Utility Model Publication No. 5-62562

However, in the above-described conventional technology, although the falling and spalling of the refractory bricks lined in the straight part of the iron shell (aligned in a straight line) to the inner side of the vacuum chamber are reduced, The effect was not sufficient, and compared to the refractory bricks lined up in the arc part of the iron shell (arranged in an arc shape), falling out and spalling to the inner side of the vacuum chamber were easy to occur.
Therefore, the present invention solves the above-mentioned problems of the prior art, and the refractory bricks lined up in a straight line portion of the iron shell and arranged in a straight line fall off the inner side of the molten steel container. It is an object of the present invention to provide a substantially oval molten steel container in which poling hardly occurs.

  In order to solve the above-described problems, an aspect of the present invention has the following configuration. That is, a substantially oval molten steel container according to one aspect of the present invention includes a cylindrical iron shell having a substantially oval horizontal cross-sectional shape, and a plurality of refractory bricks lined with the iron shell, A substantially oval molten steel container in which a molten steel accommodating portion for accommodating molten steel is formed inside a plurality of bricks made of refractory, wherein the iron skin is continuous from both ends of the linear portion and the linear portion. The horizontal cross-sectional shape is substantially oval, and the refractory bricks lined on the straight portion are arranged in a straight line along the straight iron skin. The refractory bricks lined on the arc portion are arranged in an arc along the arc-shaped iron skin, and the refractory bricks lined on the straight portion have a horizontal cross-sectional shape. It is a quadrangular prism that has a substantially trapezoidal shape. The width of the inner side edge part of the molten steel container is smaller than that, the width of the molten steel container is tapered toward the inner side of the molten steel container, and the brick group consisting of the refractory bricks lined on the straight part is The overall horizontal cross-sectional shape is substantially trapezoidal, the width of the inner end of the molten steel container is smaller than the width of the outer end of the molten steel container of the brick group, and the width tapers toward the inner side of the molten steel container. It is characterized by having a shape to become.

In this substantially oval molten steel container, the refractory brick lined on the straight portion is provided with a gradient on at least one of two side surfaces in contact with the adjacent refractory brick so that the inner side of the molten steel container The angle between the imaginary line orthogonal to the outer end surface of the molten steel container and the side surface provided with the gradient may be 0.5 ° or more and 6 ° or less.
In addition, a part of the refractory bricks lined on the straight portion has a slope in the same direction on two side surfaces in contact with the adjacent refractory bricks, and the angle of the slope is different. The shape may be such that the width tapers toward the inner side of the molten steel container.
Further, the substantially oval molten steel container may be a vacuum tank of a vacuum degassing apparatus.

  The substantially oval molten steel container according to the present invention is a refractory brick lined on a straight portion of an iron shell, is a quadrangular column whose horizontal cross-sectional shape is substantially trapezoidal, and from the width of the outer end of the molten steel container Also, the width of the inner end of the molten steel container is small, the width is tapered toward the inner side of the molten steel container, and the brick group consisting of refractory bricks lined on the straight part of the iron skin is In general, the horizontal cross-sectional shape is substantially trapezoidal, the width of the inner end of the molten steel container is smaller than the width of the outer end of the molten steel container of the brick group, and the width tapers toward the inner side of the molten steel container. Therefore, it is difficult for the refractory bricks lined up inside the straight part of the iron shell to be lined up in the molten steel container and to be spalled out.

It is a longitudinal cross-sectional view which shows the structure of the vacuum tank of the RH type vacuum degassing apparatus which is one Embodiment of the substantially oval molten steel container which concerns on this invention. It is a horizontal sectional view showing the structure of the vacuum tank of the RH type vacuum degassing apparatus which is one embodiment of the substantially oval molten steel container concerning the present invention. It is a top view of the brick made from a refractory lined by the circular arc part of the iron skin. It is a top view of the brick made from a refractory lined by the straight part of the iron skin. It is a top view of the brick made from a refractory lined by the straight part of the iron skin. It is a top view of the brick made from a refractory lined by the straight part of the iron skin. It is a top view of the brick made from a refractory lined by the straight part of the iron skin. It is a top view of the brick made from a refractory lined by the straight part of the iron skin. It is a top view of the refractory brick for connection. It is a top view of the refractory brick for connection. It is a graph which shows the wear rate of refractory bricks. It is a horizontal sectional view which shows the structure of the vacuum chamber of the conventional RH type vacuum degassing apparatus. It is a top view which shows the shape of the brick made from a refractory lining the linear part of the vacuum chamber of FIG.

An embodiment of a substantially oval molten steel container according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the structure of a vacuum tank of an RH vacuum degassing apparatus which is an embodiment of a substantially oval molten steel container according to the present invention, and FIG. 2 is an RH vacuum degassing of FIG. It is a horizontal sectional view of the vacuum chamber of the apparatus.
The vacuum degassing apparatus of FIGS. 1 and 2 includes a vacuum chamber 1 in which molten steel is accommodated and vacuum degassing is performed, and a vacuum is immersed in the molten steel in a ladle (not shown) below the vacuum chamber 1. A pair of dip tubes 2 and 2 for circulating the molten steel between the tank 1 and the ladle are provided.

The vacuum chamber 1 has a substantially oval horizontal cross-sectional shape, and has a cylindrical iron skin 11 having a substantially oval horizontal cross-sectional shape and a permanent refractory or a permanent refractory that is a permanent refractory 12. A plurality of refractory bricks 13 (standard refractory) lined on the skin 11.
The refractory bricks 13 are arranged endlessly along the circumferential direction of the iron skin 11 inside the cylindrical iron skin 11, and the iron skin is placed on the refractory bricks 13 arranged endlessly. Refractory bricks 13 arranged endlessly along the circumferential direction of 11 are further stacked. In this way, the refractory bricks 13 arranged endlessly are stacked in a plurality of stages in the vertical direction, so that the inner side of the iron skin 11 is covered with the refractory bricks 13 and these refractory bricks are lined. The molten steel accommodating part 15 which accommodates molten steel is formed inside 13.

  The iron skin 11 has a linear portion extending linearly and an arc portion continuous from both ends of the linear portion, and the horizontal cross-sectional shape is substantially oval. The refractory bricks 13A, 13B, 13C (13D, 13E) thus formed are arranged in a straight line along the straight iron skin, and the refractory brick 13Z lining the arc portion of the iron skin 11 is They are arranged in an arc along the arcuate iron skin 11.

  The refractory brick 13Z lined on the arc portion of the iron shell 11 is a quadrangular prism body whose horizontal cross-sectional shape forms a substantially isosceles trapezoid (see FIG. 3), and all the refractory bricks 13Z are substantially the same. It has a shape. Then, the side surface 13a corresponding to the longer base of the isosceles trapezoid (hereinafter referred to as “outer side end surface 13a”) faces the outer side of the vacuum chamber 1 (facing the iron shell 11), and the shorter base Side surface 13c (hereinafter referred to as "inner side end surface 13b") corresponding to the refractory brick 13 and the side surface 13c corresponding to the isosceles trapezoidal leg (hereinafter referred to as "the inner side end surface 13b"). The contact side surfaces 13 c ”are in contact with each other and are arranged along the iron skin 11. Therefore, the refractory brick 13Z lined on the arc portion of the iron shell 11 has a width at the inner end that is smaller than the width at the outer end, and faces the inner side of the vacuum chamber 1. The width is tapered.

  Next, the refractory bricks 13 </ b> A to 13 </ b> E lined on the straight portion of the iron skin 11 will be described. A plurality of refractory bricks 13A, 13B, 13C (13D, 13E) are lined on the straight portion of the iron skin 11, and the refractory bricks 13A, 13B, 13C (13D, 13E) are formed. The brick group 30 has a substantially trapezoidal horizontal cross-sectional shape as a whole, the width of the inner side end portion is smaller than the width of the outer side end portion of the brick group 30, and the width toward the inner side of the vacuum chamber 1. Is tapered (see FIG. 2).

  Moreover, although all the refractory bricks 13A, 13B, 13C (13D, 13E) constituting the brick group 30 are square pillars having a horizontal trapezoidal shape (see FIGS. 4 to 8), The shape differs depending on the arrangement location in the brick group 30. The detailed shapes of the individual refractory bricks 13A to 13E will be described in detail later, but each refractory brick 13A to 13E is similar to the refractory brick 13Z lined on the arc portion of the iron shell 11, A side surface 13a (corresponding to the “melting steel container outer side end surface” which is a constituent element of the present invention, and hereinafter referred to as “outer side end surface 13a”) corresponding to the bottom of the trapezoidal longer side of the vacuum chamber 1 The refractory bricks adjacent to each other while facing the inner side of the vacuum chamber 1 with the side surface 13b (hereinafter referred to as "inner side end surface 13b") corresponding to the shorter bottom side facing (to face the iron skin 11) The side surfaces 13 c (hereinafter referred to as “contact side surfaces 13 c”) corresponding to the legs of 13 A to 13 E and the isosceles trapezoid are brought into contact with each other and are arranged along the iron skin 11. Therefore, the refractory bricks 13 </ b> A to 13 </ b> E lined on the straight portion of the iron skin 11 are inner than the width of the outer side end portion, similarly to the refractory brick 13 </ b> Z lined on the arc portion of the iron skin 11. The width of the side end portion is reduced, and the width is tapered toward the inner side of the vacuum chamber 1.

  Between the refractory bricks 13Z lined on the arc portion of the iron skin 11 and the refractory bricks 13A to 13E lined on the straight portion of the iron skin 11, both the refractory bricks 13A to 13E are provided. , 13Z for connection of refractory bricks 13Y is arranged. The refractory brick 13Y for connection is a quadrangular prism body whose horizontal cross-sectional shape is substantially isosceles trapezoid like the refractory brick 13Z lined on the arc portion of the iron shell 11 (FIGS. 9 and 10). See).

  Here, the shape of the refractory bricks 13 </ b> A to 13 </ b> E lined on the straight portion of the iron skin 11 will be described. The number of the refractory bricks 13 constituting the brick group 30 is not particularly limited, but the shape pattern differs depending on whether it is an odd number or an even number. First, the shape of the refractory bricks 13 in the case where the number of the refractory bricks 13 constituting the brick group 30 is an odd number will be described by taking the case of five as an example. When the number of the refractory bricks 13 constituting the brick group 30 is an odd number, the shape differs between the central refractory brick 13A and the other refractory bricks 13B and 13C.

  The refractory brick 13A at the center is a quadrangular prism body whose horizontal cross-sectional shape forms a substantially isosceles trapezoid like the refractory brick 13Z lined on the arc portion of the iron shell 11. That is, as shown in FIG. 4, the two contact side surfaces 13 c and 13 c of the quadrangular prism body are inclined at the same angle (for example, 1.3 °) in the opposite direction. The width is tapered toward the side. The slope angle is an angle formed between a virtual line orthogonal to the outer side end face 13a of the refractory brick 13 and the contact side face 13c having a slope.

On the other hand, the four refractory bricks 13B and 13C other than the center are quadrangular columns whose horizontal cross-sections are substantially trapezoidal, but as shown in FIGS. , 13c are provided with gradients having different angles in the same direction, and the angles of the gradients are different, thereby forming a shape that is axisymmetric and tapered toward the inner side of the vacuum chamber 1. .
And in the refractory brick 13 which comprises the brick group 30, the angle of the gradient of the contact side surface 13c which the adjacent two refractory bricks 13 oppose is the same angle.

For example, the inclination angles of the two contact side surfaces 13c of the refractory brick 13B are 1.3 ° and 2.5 °, and the inclination angles of the two contact side surfaces 13c of the refractory brick 13C are 2.5 ° and 3.8 °.
In addition, the two refractory bricks 13B and 13B (see FIG. 5) arranged next to the central refractory brick 13A are symmetrical with respect to the central refractory brick 13A. Similarly, the two refractory bricks 13C and 13C (see FIG. 6) at both ends have a shape that is line-symmetric with respect to the central refractory brick 13A.

  As described above, the brick group 30 configured by arranging these five refractory bricks 13A, 13B, and 13C in a line has a substantially trapezoidal horizontal cross section as a whole, and the brick group 30 is located on the outer side of the brick group 30. The width of the inner side end is smaller than the width of the end, and the width is tapered toward the inner side of the vacuum chamber 1.

Next, the shape of the refractory bricks 13 in the case where the number of the refractory bricks 13 constituting the brick group 30 is an even number will be described by taking four cases as an example. When the number of the refractory bricks 13 constituting the brick group 30 is an even number, the shape differs between the central two refractory bricks 13D and 13D and the other refractory bricks 13E and 13E.
The two refractory bricks 13D and 13D (see FIG. 7) in the center are quadrangular columns whose horizontal cross-sectional shapes are substantially trapezoidal, and are inclined only on one of the two contact side surfaces 13c and 13c of the quadrangular column. The other is orthogonal to the outer side end face 13a and the inner side end face 13b, has a shape that is axisymmetric and tapers inward toward the inner side of the vacuum chamber 1.

  On the other hand, the two refractory bricks 13E and 13E (see FIG. 8) at the end are quadrangular columns whose horizontal cross-sectional shapes are substantially trapezoidal, but the refractory bricks 13 constituting the brick group 30 are It is the same shape as the refractory bricks 13B, 13C other than the center in the case of an odd number, and the two contact side surfaces 13c, 13c of the quadrangular prism body are provided with gradients of different angles in the same direction, Due to the difference in the angle of the gradient, the shape is non-linearly symmetric and the width tapers toward the inner side of the vacuum chamber 1.

And in the refractory brick 13 which comprises the brick group 30, the angle of the gradient of the contact side surface 13c which the adjacent two refractory bricks 13 oppose is the same angle.
As an example, the slope angle of the contact side surface 13c with the slope of the refractory brick 13D is 2.5 °, and the slope angle of the two contact side surfaces 13c of the refractory brick 13E is 2 °. .5 ° and 3.8 °.

The two refractory bricks 13D and 13D at the center have a shape that is line-symmetric with each other, and the two refractory bricks 13E and 13E at the end have a shape that is also line-symmetric with each other. .
As described above, the brick group 30 constituted by arranging these four refractory bricks 13D and 13E in a line has a substantially trapezoidal horizontal cross section as a whole, and the outer side end portion of the brick group 30 is formed. The width of the inner side end portion is smaller than the width of the vacuum chamber 1, and the width is tapered toward the inner side of the vacuum chamber 1.

  As described above, the refractory bricks 13 arranged endlessly are stacked in a plurality of stages in the vertical direction. In that case, the refractory bricks 13A, 13B, 13C lined on the straight portion of the iron shell 11 are stacked. About (13D, 13E), it is preferable that the number of the refractory bricks 13 constituting the brick group 30 is alternately stacked with an odd number of steps and an even number of steps. Thereby, it can avoid that the position of the boundary of the adjacent refractory bricks 13 overlaps in the upper and lower stages.

  In FIG. 2, the brick group 30 on the upper side of the vacuum chamber 1 is composed of an odd number of refractory bricks 13, and the brick group 30 on the lower side of the sheet is composed of an even number of refractory bricks 13. The two brick groups 30 are illustrated as being located on the same stage, but are illustrated in this manner for convenience of explanation, and the two brick groups 30 are located at different stages in the vacuum chamber 1. It is.

In the vacuum tank 1 configured in this manner, in all the refractory bricks 13, the contact side faces 13c of the adjacent refractory bricks 13 are inclined (the refractory brick 13D is one of the contact side faces). 13c only). Therefore, not only the refractory brick 13Z lined on the arc portion of the iron skin 11, but also the refractory bricks 13A, 13B, 13C (13D, 13E) lined on the straight portion of the iron skin 11 are adjacent to each other. Refractory bricks 13 compete with each other. Therefore, any refractory brick 13 is unlikely to fall out to the inner side of the vacuum chamber 1.
Moreover, even if a crack etc. generate | occur | produce in the refractory brick 13 and it breaks and the division | segmentation of the inside / outside direction arises, the vacuum tank 1 of the inner side part of the refractory brick 13 by the competition between refractory bricks 13 mutually. Peeling (spoling) to the inner side is less likely to occur.

  Furthermore, since the refractory brick 13 does not slip or fall out during the construction of the vacuum chamber 1 and can be constructed easily, the construction time can be greatly shortened, and the refractory brick over time. Even if the wear and tear of No. 13 progresses and the remaining size decreases, it is difficult for the vacuum chamber 1 to fall out inward, so that the life of the vacuum chamber 1 can be extended and stable operation can be achieved. Furthermore, since the frequency of the repair work that has been carried out for damage or falling off of the refractory brick 13 can be reduced, and the amount of repair material used in the repair work can be reduced, the vacuum chamber 1 Operating costs can be reduced.

Here, the vacuum chamber (shown in FIG. 2) of the present embodiment as described above and the conventional vacuum chamber (refractory brick shown in FIG. The wear rate due to spalling or the like of the inner side portion of the refractory brick was compared with that of an oblong vacuum chamber. The results are shown in the graph of FIG.
In the vacuum chamber of this embodiment, the wear rate of the refractory bricks lined on the straight part of the iron skin was 12% lower than that of the conventional vacuum chamber. Note that the wear rate of the refractory brick lined on the arc portion of the iron shell is not different between the vacuum chamber of the present embodiment and the conventional vacuum chamber, and is therefore collectively shown in the graph of FIG. .

  In the refractory bricks 13A to 13E lined on the straight part of the iron skin 11, in order to sufficiently cause the competition between adjacent refractory bricks 13A to 13E, in any of the refractory bricks 13A to 13E However, the angle (gradient angle) formed between the imaginary line orthogonal to the outer side end face 13a and the contact side surface 13c provided with the gradient is preferably 0.5 ° or more and 6 ° or less, and preferably 1 ° or more and 4 More preferably, it is not more than 0 °.

  When the angle of the gradient is less than the lower limit, competition is not likely to occur sufficiently, and the refractory bricks 13A to 13E may be easily dropped or spalled. On the other hand, when the angle of the gradient exceeds the upper limit, it may be difficult to perform construction in the furnace. In addition, if the angle of a gradient is in the said numerical range, the effect that there is little damage to the refractory bricks 13A-13E by the influence of heat is also show | played.

In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment.
For example, the inner side end surface 13b of some refractory bricks 13 is formed on the outer side end surface 13a so that the inner peripheral surface of the endless refractory bricks 13 has a smooth curved surface and no step is generated. It may be a non-parallel inclined surface.

  For connecting the refractory bricks 13 between the refractory bricks 13Z lined on the arc part of the iron skin 11 and the refractory bricks 13A to 13E lined on the straight part of the iron skin 11 Refractory bricks 13Y (two each in the example of FIG. 2) are arranged, and the refractory bricks 13Y for connection and the refractory bricks in contact with the refractory bricks (lined on the arc portion of the iron skin 11) The refractory bricks 13Z and the refractory bricks 13C and 13E lined on the straight portions of the iron skin 11 are not aligned with the corners of the inner side end portions, so that the refractories arranged endlessly. The inner side end face of the brick 13 is not smoothly continuous and a step is formed, and spalling is likely to occur at the corner of the step (see FIG. 12).

  Therefore, for example, as shown in FIG. 2, a refractory brick 13Y for connection (see FIG. 10) that contacts the refractory brick 13Z lining the arc portion of the iron shell 11, and a refractory made of connection. For the refractory bricks 13C and 13E lined on the straight portion of the iron skin 11 in contact with the brick 13Y, the inwardly facing end surface 13b is an inclined surface that is not parallel to the outwardly facing end surface 13a, and the refractory bricks that are in contact with each other. If the corners of the inner side end portions of 13 coincide with each other, the inner side end surface 13b of the refractory bricks 13 arranged endlessly smoothly continues, so that no step is generated. Therefore, it is difficult for spalling to occur at the inner end of the refractory brick 13.

  Further, the refractory bricks 13A to 13E lined on the straight portion of the iron skin 11 are thicker than the refractory brick 13Z lined on the arc portion of the iron shell 11 (the inner side end face 13b and the outer side). It is preferable to increase the distance between the side end face 13a. If it does so, even if spalling arises in the inner side part of refractory bricks 13A-13E, since many parts remain, the lifetime of the vacuum chamber 1 can be extended. Furthermore, since friction with the adjacent refractory bricks 13A to 13E is increased, the refractory bricks 13A to 13E are unlikely to fall out inward of the vacuum chamber 1.

  Furthermore, the refractory brick 13 preferably has a high thermal conductivity. If it does so, it will become difficult to produce the crack and crack resulting from the temperature difference of the inner side part of the refractory brick 13 and an outer side part. In order to improve the thermal conductivity of the refractory brick 13, it is preferable to add a component having a high thermal conductivity such as carbon.

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 11 Iron skin 13 Refractory brick 13a Outer side end surface 13b Inner side end surface 13c Contact side surface 13A-13E Refractory brick 1313 lined in the linear part of the iron skin Refractory bricks 30 bricks

Claims (4)

A molten steel container that includes a cylindrical iron shell having a substantially oval horizontal cross-sectional shape and a plurality of refractory bricks lined on the iron shell, and accommodates molten steel inside the plurality of refractory bricks. A substantially oval molten steel container formed with a portion,
The iron skin has a linear portion extending linearly and a circular arc portion continuous from both ends of the linear portion, and the horizontal cross-sectional shape is substantially oval, and the fireproof lined on the linear portion. The product bricks are arranged in a straight line along the straight iron skin, and the refractory bricks lined on the arc part are arranged in an arc along the arc shaped iron skin. The refractory brick lined on the straight portion is a quadrangular prism having a substantially trapezoidal horizontal cross section, and the width of the inner end of the molten steel container is wider than the width of the outer end of the molten steel container. The brick group consisting of the above-mentioned refractory bricks lined on the straight part has a substantially trapezoidal horizontal cross section as a whole. The width of the outer edge of the molten steel container of the brick group A substantially oval molten steel container characterized in that the inner end of the molten steel container has a small width and tapers toward the inner side of the molten steel container.   The refractory brick lined on the straight portion has a shape in which the width is tapered toward the inner side of the molten steel container by providing a gradient on at least one of two side surfaces in contact with the adjacent refractory brick. The angle formed by the imaginary line orthogonal to the outer side end surface of the molten steel container and the side surface with the gradient is 0.5 ° or more and 6 ° or less. A generally oval molten steel container.   A part of the refractory bricks lined on the straight part is inclined in the same direction on two side surfaces in contact with the adjacent refractory bricks, and the angle of the gradient is different, so that the molten steel The substantially oval molten steel container according to claim 1 or 2, wherein the container has a shape in which a width is tapered toward an inner side of the container.   It is a vacuum tank of a vacuum degassing apparatus, The substantially oval molten steel container as described in any one of Claims 1-3 characterized by the above-mentioned.

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