JP4770524B2 - Bottom structure of bottom blow converter - Google Patents

Description

  The present invention relates to a bottom structure of a bottom blowing converter in which oxidizing refining gas is blown from the bottom of the furnace, in particular, a bottom structure of a bottom blowing converter formed by laying a plurality of brick rows in parallel. Relates to the bottom structure of a bottom-blown converter having a plurality of tuyere bricks. The bottom blowing converter according to the present invention includes not only a so-called Q-BOP converter in which an oxidizing gas, particularly pure oxygen, is blown only from the bottom of the furnace, but also an upper bottom blowing in which an oxidizing gas is blown through the lance from the furnace port side together with the furnace bottom. A converter is included. The tuyere means a double pipe tuyere in which oxidizing gas is blown from the central part and cooling gas, for example, hydrocarbon gas is blown from the peripheral part.

  Among bottom converters for steel making, top-bottom blow converters and bottom-blowing converters (hereinafter collectively referred to as “bottom blow converters”) are used to oxidize gases such as pure oxygen from the bottom of the furnace during the refining process. Because of this, the molten steel is strongly stirred during the refining process, so the reaction efficiency is high and it is suitable for refining high-quality steel. In this type of bottom-blown converter, as is well known, a tuyeres made of stainless steel or copper are provided at the bottom of the furnace, and an oxidizing gas such as pure oxygen is blown into the converter from there. Yes. In addition, the tuyere tube has a double tube comprising an inner tube through which an oxidizing gas such as pure oxygen is passed and an outer tube surrounding the inner tube through which a cooling gas such as hydrocarbon gas (typically propane) is passed. It has been adopted to cool the tuyere around the refining process. This cooling action is caused by the decomposition of hydrocarbons around the tuyere during the refining process, and as a result, so-called mushrooms are formed around the tuyere, thereby protecting the tuyere pipe and tuyere brick from melting. It has come to be.

  A typical bottom structure of a bottom-blown converter having such tuyere tubes and tuyere bricks is shown in FIG. As shown here, the bottom structure of the bottom-blown converter is to form the furnace bottom by laying a plurality of brick rows in parallel, and the tuyere bricks are almost evenly along the furnace bottom diameter direction, And only one is arranged in each brick row. The tuyere tube is held between the tuyere bricks and maintained in a predetermined position. In other words, it is not done to arrange a plurality of tuyere bricks, and thus a plurality of tuyere tubes, in a particular brick row. The reason is as follows.

  That is, the cooling action caused by the pyrolysis action of hydrocarbon gas extends to the tuyere tube and tuyere bricks sandwiching it, but not directly to the surrounding furnace bottom bricks. Therefore, as shown in FIG. 5 (a), when the bottom bricks 53a, 53b, 53c, 53d and the plurality of tuyere bricks 52a, 52b are arranged in a specific brick row 50, in the refining stage, FIG. As schematically shown in (b), the furnace bottom bricks 53b, 53c between the tuyere bricks 52a, 52b expand in comparison with the tuyere bricks 52a, 52b in the vicinity of the portion in contact with the molten steel, thereby the tuyere tube This is because troubles such as deformation of 54a and 54b occur.

JP2004-285441

For the above reasons, in the furnace bottom structure of a conventional bottom-blown converter, as shown in FIG. 6, a plurality of bricks rows 50 _1, 50 _2, 50 _3, furnace by laying in parallel · · · 50 _n The bottom 51 is formed, and the tuyere bricks 52 ₁ , 52 ₂ , 52 ₃ , 52 _m are arranged almost evenly in the diameter direction of the furnace bottom, and only one brick is arranged in each brick row. There is no arrangement of multiple tuyere bricks in a row. However, such restrictions on arrangement have the following problems in operation.

  That is, when the furnace bottom structure is adopted, it also depends on the shape of the mushroom, but when the distance between the tuyere is small, as shown in FIG. It flows along the joint 55 between the bricks and selectively melts the joint 55. Then, starting from such a selective melted portion, as shown in FIG. 8, a so-called mortar-shaped worn portion 56 is formed between the tuyere bricks 52a and 52b, and the remaining thickness is sufficient in other portions. In spite of this, the entire furnace bottom had to be replaced, which shortened the converter life. Therefore, the conventional furnace bottom structure has a restriction that it is necessary to increase the distance between tuyere, and there is a problem that a large number of tuyere cannot be taken.

  The present invention aims to solve the problems of the furnace bottom structure of the conventional bottom blow converter, and even if the distance between the tuyere is small, there is no deformation of the tuyere due to expansion of the furnace bottom brick, and The purpose of this study is to propose a bottom structure of a bottom-blown converter where the joints between the tuyere bricks are not easily melted.

  The present inventor, when placing the tuyere bricks in a specific brick row in the brick row laid in the furnace bottom diameter direction, if the inter-tuyer bricks are sufficiently cooled by the tuyere bricks, It was found that expansion was suppressed, and in turn, melting of the joints between the tuyere bricks was suppressed, and the life of the bottom blown converter was extended.

  The present invention provides a furnace bottom structure of a bottom blow converter in which a plurality of brick rows are arranged in parallel to form a furnace bottom. Among the brick rows, one specific brick along the furnace bottom diameter is provided. A plurality of tuyere bricks sandwiching tuyere pipes in a row and, when placing the tuyere bricks, one inter-brick brick is interposed between the tuyere bricks. is there.

  In the above invention, the tuyere bricks are preferably arranged evenly in the tuyere arrangement region in the brick row, and are preferably arranged so that the interval between the tuyere is 400 mm or less.

  According to the present invention, even if the bottom blow converter has a small distance between tuyere, there is no deformation of tuyere due to expansion of the bottom brick, and the joints between the tuyere bricks are not easily melted. As a result, it was possible to increase the number of tuyere arranged at the furnace bottom, and to improve the operation efficiency of the converter.

  The converter to which the present invention is applied is a bottom blowing converter. This includes a so-called Q-BOP converter in which oxidizing gas is blown only from the furnace bottom, and an upper bottom blowing converter in which oxidizing gas is blown from the furnace bottom side through a lance together with the furnace bottom. In addition to pure oxygen, the oxidizing gas includes, for example, a mixed gas of oxygen gas and argon gas used at the end of decarburization in the converter operation.

FIG. 1 is a plan view of the bottom structure of the bottom blow converter to which the present invention is applied. As can be understood from FIG. 1, also in the present invention, the brickwork structure at the bottom of the converter furnace is a well-known and normally used form, and a plurality of brick rows 10 ₁ , 10 ₂ , 10 ₃ ,. 10 _n are arranged in parallel. As shown in Patent Document 1, the brick used for the construction of the bottom portion of such a converter furnace is, for example, an MgO-C brick, and the brick stacking structure includes a large number of bricks, as is well known. Brick rows are arranged in a row, and this is laid in parallel to the furnace bottom diameter.

In the example shown in FIG. 1, the tuyere brick 11 ₁ to 11 ₈ are placed in a particular brick column 10 _m of the converter furnace bottom constructed in this manner, the tuyere bricks 11 ₁ to a particular brick column 10 _m 11 ₈ is arranged. The tuyere bricks 11 _{1 to} 11 ₈ are bricks that support the tuyere tube forming the tuyere and are divided into two, and the tuyere tubes are sandwiched in pairs. The material is, for example, MgO-20% C brick. In addition, the specific brick row (10 _{m in the} example shown in FIG. 1) where the tuyere tube is arranged exists along the diameter, that is, substantially on the diameter of the furnace bottom. It is allowed to deviate within the range of the numerical sequence.

The arrangement of the tuyere bricks 11 within a specific brick row 10 _m is shown in FIG. 2, which is a partially enlarged view of FIG. (Hereinafter referred to as “the tuyeres brick”). Specifically, for example, only one furnace bottom brick 12b is interposed between tuyere bricks 11a and 11b in which tuyere tubes 14a and 14b are inserted and supported. As a result, the furnace bottom brick 12b receives the cooling action from the tuyere bricks 10a and 10b, and it is possible to avoid a large temperature rise and thermal expansion even during the blowing operation of the converter. The furnace bottom bricks 53a, 53b (brick between the tuyere) between the tuyere bricks 52a, 52b as explained with reference to Fig. 5 expand in comparison with the tuyere brick in the vicinity of the portion contacting the molten steel, thereby It is possible to avoid the occurrence of obstacles such as deformation of 54a and 54b.

  The reason that the number of inter-tuyere bricks 12 is one is that when there are two or more bricks, cooling from the tuyere bricks 11 is not sufficiently performed due to joints interposed therebetween. Therefore, in order to obtain the effect of the present invention, it is essential that the number of bricks between the tuyere is one or less, but the thickness of the tuyere brick is further adjusted so that the interval between the tuyere is 400 mm or less. It is desirable to be

  FIG. 3 is a relationship diagram of the brick internal temperature with respect to the distance from the tuyere center, that is, the temperature at a position of 100 mm from the top surface of the brick, when the distance between the tuyere is 400 mm and 500 mm. As shown here, when the interval between tuyere exceeds 400 mm, the brick in the center between tuyere is not sufficiently cooled, the brick temperature rises at that part, and as a result, the brick between tuyere Problems such as significant thermal expansion and deformation of the tuyere occur. Therefore, as described above, it is desirable to adjust the thickness of the bricks between tuyere so that the spacing between tuyere is 400 mm or less.

As such a tuyeres brick, a normal furnace bottom brick can be used as it is, but it is desirable to use it by appropriately trimming it in the thickness direction and adjusting its thickness appropriately. As a result, the inter-tuyere brick can be used as a spacer in the construction of the furnace, and the tuyere brick can be arranged in the specific brick row 10 _m without looseness.

  With the above configuration, the bottom structure of the bottom blow converter is realized even when the distance between the tuyere is small, the tuyere is not deformed due to the expansion of the bottom brick, and the joints between the tuyere bricks are not easily melted. However, it is desirable for the converter operation that the tuyere bricks are evenly arranged in the tuyere placement area in a specific brick row. Here, the “tuyere placement area” means a brick row including tuyere bricks and inter-tuyere bricks, and means a region in which tuyere bricks are placed. This refers to the part excluding the furnace bottom brick that touches the periphery of the furnace bottom.

  Therefore, outside the “tuyere placement area”, the bottom brick is constructed so that it is normally adopted. However, the bottom brick constructed in this area is heated to a high temperature during the converter operation. However, there is no compression on the tuyere bricks, so there is no need to pay special attention to the structure.

  FIG. 4 shows the number of times of blowing (also referred to as the number of charges or the number of bottoms) when blowing using the bottom brick array converter of the present invention and the bottom blowing converter having the conventional bottom brick arrangement. It is a relationship figure with the remaining thickness (mm) of a tuyere. Here, the converter life is measured as the number of times of blowing until replacement of the furnace bottom brick, and in this case, it corresponds to when the remaining tuyere thickness becomes 200 mm. According to the result shown in FIG. 4, in the conventional example, the converter life was about 500 times, but it was extended to 630 times according to the present invention.

The specifications of the converter used in the above test are as follows.
(Common subject matter)
Converter type and capacity: Top-bottom blowing converter (nominal 180t)
Furnace bottom diameter: 3100mm

(Example of the present invention)
Furnace bottom style: It has a furnace bottom structure according to FIG. 1 and its main dimensions are as follows.
Number of brick rows: 25 rows Number of tuyer bricks arranged: 14th Row number of tuyer bricks: 16 Size of tuyere bricks: width 115mm x length 1700mm x thickness 120mm
Dimensions between bricks at the tuyere: width 115mm x length 1700mm x thickness 120mm
Distance between tuyere: 345mm

(Conventional example)
Furnace bottom style: It has a furnace bottom structure according to FIG. 6 and its main dimensions are as follows.
Number of brick rows: 25 rows Number of tuyere bricks: 16 Feather brick dimensions: width 115 mm x length 1700 mm x thickness 120 mm
Dimensions between bricks at the tuyere: width 115mm x length 1700mm x thickness 120mm
Distance between tuyere: 345mm

It is a top view of the furnace bottom part structure of the bottom blow converter to which this invention is applied. It is a partially schematic enlarged view of FIG. 1, and is a cross-sectional view of the bottom structure of the bottom blow converter to which the present invention is applied. It is a relationship figure of the brick internal temperature with respect to the distance from a tuyere center. Remaining amount of tuyere (mm) with respect to the number of times of blowing (number of charges) when blown using the bottom-brick array converter of the present invention and the bottom-blow converter having the conventional bottom-brick arrangement FIG. It is a schematic diagram of a failure occurrence situation when a plurality of tuyere bricks are arranged at a distance in a brick row at the furnace bottom. It is a top view of the furnace bottom part structure of the conventional bottom blow converter. It is a schematic diagram which shows the erosion situation of a joint when the distance between tuyere is small in the furnace bottom part structure of the conventional bottom blow converter. It is a schematic diagram which shows the erosion situation of the brick between tuyere in the furnace bottom part structure of the conventional bottom blow converter shown in FIG.

Explanation of symbols

10: Brick row
11: tuyere brick
12: Brick between tuyere
14: tuyere tube
50: Brick row
51: Furnace bottom
52: tuyere brick
53: Furnace bottom brick
54: tuyere tube

Claims (3)

In the bottom blowing structure of the bottom blowing converter formed by arranging a plurality of brick rows in parallel to form the furnace bottom,
Among the brick rows, a plurality of tuyere bricks sandwiching tuyere pipes are arranged in one specific brick row along the furnace bottom diameter, and the tuyere bricks are arranged in arranging the tuyere bricks. A bottom structure of a bottom-blowing converter characterized by interposing one inter-tuyer brick between them.   The bottom structure of a bottom blow converter according to claim 1, wherein the tuyere bricks are evenly arranged in the tuyere arrangement region in the brick row. The bottom structure of a bottom blow converter according to claim 1 or 2, wherein the tuyere bricks are arranged so that the interval between tuyere is 400 mm or less.

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