JP6665743B2 - Blast furnace bosh section structure and blast furnace design method - Google Patents

Description

  The present invention relates to a blast furnace bosh section structure and a blast furnace design method.

Conventionally, the morning glory of the blast furnace is made of steel, cooling staves provided inside the steel (hereinafter simply referred to as staves), and refractory bricks provided inside the staves to protect the staves. , Is provided. A castable or the like is appropriately filled between the steel bar and the stave.
With the operation of the blast furnace, the internal structure of the morning glory described above is worn. First, the refractory brick is worn out, and subsequently the stave is eroded. As the wear of the stave progresses, the steel shell cannot be protected, and the deformation and cracks caused by the increase in the temperature of the steel shell cause the morning glory of the blast furnace to reach its end of life.

In a blast furnace, operation management is performed so as to obtain an appropriate operation state while taking into consideration a huge number of parameters. However, in many blast furnaces, large fluctuations in operation results occur during one furnace cost, that is, about 15 years, which is the life span. In particular, it is known that a period during which several years have passed since the start of operation of the blast furnace after the burn-in of the blast furnace significantly reduces the operation results.
It is considered that such a decrease in the operation results of the blast furnace is due to the fact that structures such as refractory bricks on the inner surface of the furnace of the blast furnace are worn away with the operation after burning, and the profile of the inner surface of the furnace changes.
That is, in the initial operation state immediately after burning of the blast furnace, the shape of the furnace inner surface is defined by the surface of the refractory bricks stacked inside the furnace. As time elapses from the start of operation of the blast furnace, local wear of refractory bricks proceeds. As a result, the profile (contour shape appearing in the vertical section) of the furnace inner surface becomes inappropriate, and the circumferential balance (the circumferential shape appearing in the horizontal section) may become non-uniform. If the surface shape in the blast furnace is inappropriate, the gas flow and the distribution of the contents in the furnace become unstable, which causes a decrease in the operation results.

After such an unstable period, a period of stable operation of the blast furnace continues. This is considered to be because most of the refractory bricks have disappeared, and an approximately proper profile or circumferential balance close to the initial stage of burning can be obtained by the attached layer formed on the inner surface of the stave furnace.
Most of the refractory brick installed inside the blast furnace disappears due to thermal shock and wear from the time the blast furnace is fired until the stable operation. However, it is considered that a deposit layer due to the charge is formed on the stave surface inside the furnace, and this deposit layer compensates for a worn portion of the furnace inner surface (self-fringing effect).
Among the blast furnaces, the surfaces inside the furnace, especially in the bosh section and the abdomen, are exposed to a high-temperature cohesive zone (the ore in the charge begins to soften and melt, and the semi-molten ores fuse together to form a plate. Because it comes into contact with the root of the (connected area), it is subject to wear due to high heat. That is, when the root of the cohesive zone comes into contact with the stave body, thermal load and wear occur on the stave body. The deposits generated on the stave surface in the blast furnace during the above-mentioned stable operation of the blast furnace have a protective action against the thermal load and wear, and repair the lost portion of the refractory brick in the furnace. It is thought that if this repair can maintain the appropriate thickness of the deposit layer and the furnace profile, further long-term stable operation and long life of the blast furnace will be possible.

Patent Literature 1 is known as a technique for avoiding inappropriate profile or circumferential balance of the furnace inner surface due to damage to the refractory brick of the blast furnace as described above. Patent Literature 1 discloses that a refractory brick is not installed on the inner surface of a stave, and the inner surface of the stave is used as a furnace inner wall, thereby preventing a change in a furnace inner surface shape due to wear of the refractory brick. Is described.
Further, Patent Document 2 discloses that a cooling member is installed near a tuyere in order to positively guide the deposits generated on the stave surface.
According to these techniques, by omitting the refractory brick inside the stave, it is possible to avoid a rapid change in the furnace inner surface shape due to wear of the refractory brick from after the blast furnace is burned until the operation is stabilized. In addition, it is possible to suppress the wear of the stave even without the refractory brick due to the induction of the deposit.

However, in Patent Literatures 1 and 2, it is difficult to stably generate the furnace inner surface shape formed by the deposit layer on the stave surface in the height direction and the furnace circumferential direction of the blast furnace for a long time. In addition, the profile in the blast furnace changes due to changes in the charge and operating conditions during the operation of the blast furnace. In particular, when the circumferential balance of the furnace inner surface profile in the furnace circumferential direction of the blast furnace changes, the stable operation of the blast furnace is impaired, and the productivity is reduced.
Further, in the structure of the blast furnace in which no refractory brick is installed inside the stave as in the structure described in Patent Document 1, the stave and the steel shell are rapidly heated from room temperature to a high temperature of about 1500 to 2000 ° C. when the blast furnace is fired. . For this reason, there is a possibility that the stave may be damaged due to heat shock, that is, sudden heat fluctuation. Therefore, it is desirable to cover the inner surface of the stove with refractory bricks when constructing the blast furnace. Even when such a refractory brick is provided, there is a demand for a blast furnace capable of stably maintaining an appropriate furnace surface profile over a long period without a sudden change in the furnace surface profile in the early stage of operation after burning.

In response to these demands, in the early stage of operation after burning the blast furnace, after the refractory brick on the inner surface of the stave has disappeared due to thermal shock or wear, a deposit layer should be quickly formed on the inner surface of the stave. Thus, a blast furnace bosh section structure capable of forming a furnace surface profile having a favorable operation stable period while suppressing a rapid change in the furnace inner surface profile, and a design method thereof have been developed.
The blast furnace bosh section of Patent Literature 3 is provided between the tuyere part of the blast furnace and the furnace abdomen, and has a tubular bosh section having a diameter that increases vertically upward. An iron shell, a copper or copper alloy morning glory stave provided on the inner periphery of the iron shell, and a refractory brick provided on an inner periphery of the morning glory stave; The horizontal thickness of the refractory brick at the position is 50 to 250 mm; the horizontal thickness of the refractory brick at the lower edge position of the bosh is 200 to 500 mm; when the bosh is viewed in a cross section including its axis. The narrow angle between the surface of the morning glory stave and the horizontal plane is 75 to 82 °.
With this configuration, in the early stage of operation after burning of the blast furnace, the inclination angle of the deposit that naturally occurs on the furnace inner surface of the stave after the refractory bricks disappears is close to the inclination angle (about 75 °) in the above-described stable operation period of the blast furnace. You can do so. This can suppress a rapid change in the furnace inner surface profile that occurs from the initial operation after burning of the blast furnace to the stable operation of the blast furnace, so that instability of the operation and reduction in productivity can be avoided.

JP 2002-115007 A JP 2005-194567 A Japanese Patent No. 4575960

Patent Literature 3 has made it possible to stabilize the operation of a blast furnace and improve productivity, but it has been found that there are further problems when actually operated.
In particular, in the upper part of the tuyere, it was found that the fluctuation of the initial brick or the formation of the deposits falling or reforming was more remarkable than expected, and that the influence hindered the stabilization of the operation and the improvement of the productivity.

That is, in the bosh section of the blast furnace based on Patent Document 3, by setting the narrow angle between the surface of the bosh section stave and the horizontal plane to be 75 to 82 °, an appropriate deposit layer is formed on the bosh section stave. Thus, it is possible to form a good furnace inner surface profile in a stable operation period while suppressing a rapid change in the furnace inner surface profile.
In contrast, in the lower part of the bosh section, a firebrick having a conventional thickness is stacked between the bosh section stave and the tuyere.

Because of the refractory brick portion, the thickness of the deposits generated during operation varies greatly just above the tuyere by the thickness of the refractory brick, and changes in the furnace inner surface profile, including the circumferential balance, occur. It is thought that the influence of the above is likely to occur.
However, the refractory brick having the above-mentioned conventional thickness in the lower part of the bosh section is provided for the purpose of avoiding damage to the tuyere (hot metal attack) due to the high-viscosity molten iron mass falling in the furnace, and is omitted. Difficult to do.
Therefore, in the blast furnace disclosed in Patent Document 3, it is required to stabilize the furnace inner surface profile including the circumferential balance immediately above the tuyere while protecting the tuyere.

  An object of the present invention is to provide a blast furnace bosh section structure and a method of designing a blast furnace that can stabilize a furnace inner surface profile including a circumferential balance even immediately above the tuyere while protecting the tuyere. .

  The blast furnace bosh section structure of the present invention is provided between the tuyere part of the blast furnace and the furnace abdomen, and is a blast furnace bosh section structure that constitutes a cylindrical bosh section that expands in diameter vertically upwards, The bosh section has an annular steel shell, a copper or copper alloy bosh section stave provided on the inner periphery of the iron shell, and a firebrick provided on the inner periphery of the bosh section stave. A tuyere cooling box capable of inserting a tuyere nozzle from the outside of the furnace is provided below the bosh section, and an upper furnace inner surface and a lower furnace inner surface are formed on a furnace inner surface of the bosh section stave. The upper furnace inner surface has an inclination angle of 75 to 82 ° with respect to a horizontal plane, and the lower furnace inner surface has an inclination angle with respect to a horizontal plane that is smaller by 2 to 15 ° than the inclination angle of the upper furnace inner surface with respect to a horizontal plane. It is characterized by the following.

In the present invention, the inclination angle with respect to the horizontal plane is set to 75 to 82 ° in the upper furnace inner surface among the furnace inner surfaces of the bosh section stave, so that the appropriate furnace according to Patent Document 3 described above can be obtained. It is possible to realize the generation of deposits and to stabilize the furnace inner surface profile including the circumferential balance.
On the other hand, on the lower furnace inner surface, by making the inclination angle with respect to the horizontal plane smaller by 2 to 15 ° than the inclination angle of the upper furnace inner surface with respect to the horizontal plane, the inclination becomes more gentle than the upper furnace inner surface. It is possible to positively induce the accumulation of deposits on the upper part. This makes it possible to sufficiently protect the tuyere with the bosh section stave and the deposits on the surface thereof. As a result, it is no longer necessary to install a refractory brick having a conventional thickness between the bosh section stave and the tuyere, and the furnace inner surface profile including the circumferential balance can be stabilized just above the tuyere. be able to.

In the present invention, a plurality of staves for a bosh section may be provided in a vertical direction in an area to be a bosh section of a blast furnace.
The upper furnace inner surface and the lower furnace inner surface may be formed over a plurality of staves in the vertical direction, respectively.
The boundary between the upper furnace inner surface and the lower furnace inner surface may be set in the middle of the same stave, or may be aligned with the boundary between staves.
The upper end of the upper furnace inner surface does not need to be aligned with the upper end edge of the bosh stave, and the upper furnace inner surface may be formed downward from the middle of the stave.
The lower end of the bosh section stave (the lower end of the lower furnace inner surface) may be located away from the tuyere cooling box. It is desirable to fill the gap between the lower end of the bosh section stave and the tuyere cooling box with refractory bricks. At this time, it is desirable that the furnace inner surface of the refractory brick is continuous with the lower furnace inner surface formed on the bosh section stave.
The inclination angle of both the upper furnace inner surface and the lower furnace inner surface may be 75 °. In this case, the upper furnace inner surface and the lower furnace inner surface are continuous on the same plane.
However, in view of the function of accelerating the formation of deposits immediately above the tuyere, it is desirable that the inclination angle of the lower furnace inner surface be smaller (slower) than the inclination angle of the upper furnace inner surface.

  In the blast furnace bosh section structure of the present invention, it is preferable that the lower furnace inner surface is located at a position crossing a position of 0 to 300 mm from the front end of the tuyere cooling box to the outside of the furnace when extended.

  According to the present invention, the tuyere cooling stove having the lower furnace inner surface and the deposits thereon can cover the tuyere cooling box more widely than before without affecting the injection of the tuyere. Sufficient protection performance can be obtained for the mouth cooling box.

  In the blast furnace bosh section structure of the present invention, it is preferable that an upper end of the upper furnace inner surface is arranged at 4300 to 5500 mm from a center height of the tuyere nozzle.

The inner surface of the blast furnace bosh section supports the root of the cohesive zone of the charge descending in the furnace and plays a role in maintaining stable operation of the blast furnace.
Therefore, by setting the height of the upper edge position of the morning glory stave to the above range, even when the height position of the root portion of the cohesive zone of the charged material fluctuates due to a change in the operation state of the blast furnace, the feathers are set. The bosh section stave is placed above the mouth at an appropriate inclination angle (the angle between the lower furnace inner surface and upper furnace inner surface described above), and the vertical direction from the center of the tuyere to the upper edge position of the bosh section is set. By setting the dimension to a sufficient length, the root of the cohesive zone can be stably supported.

The method for designing a blast furnace according to the present invention includes a tuyere portion, a furnace belly portion, and a tubular bosh section provided between the tuyere portion and the furnace belly portion and having a diameter that increases vertically upward. The part has an annular steel shell, a copper or copper alloy bosh section stave provided on the inner circumference of the steel shell, and a firebrick provided on the inner circumference of the bosh section stave, A method for designing a blast furnace having a tuyere cooling box into which a tuyere nozzle can be inserted from the outside of the furnace, wherein the upper surface of the bosh section and the lower furnace are provided on the inner surface of the stave for the bosh section. Arranging the upper reference position at a position above the predetermined height from the center height of the tuyere nozzle and extending the inner surface of the stave located in the belly of the furnace downward, Below the upper reference position and inside the furnace, the upper side with an inclination angle of 75 to 82 ° with respect to the horizontal plane Forming the upper furnace inner surface along the reference plane, setting a lower reference position at a predetermined distance from the furnace inner end of the tuyere cooling box to the furnace outside, and setting the furnace upper and lower sides from the lower reference position The lower furnace inner surface is formed along a lower reference plane having an inclination angle with respect to a horizontal plane that is smaller than the inclination angle of the upper reference plane with respect to the horizontal plane by 2 to 15 °.
According to such a blast furnace design method of the present invention, the above-described blast furnace bosh section structure of the present invention can be appropriately designed, and the operational effects as described in the blast furnace bosh section structure can be obtained.

  According to the present invention, there is provided a blast furnace bosh section structure and a blast furnace design method which can stabilize a furnace inner surface profile including a circumferential balance even immediately above the tuyere while protecting the tuyere. be able to.

Sectional drawing which shows one Embodiment of the blast furnace based on this invention. Sectional drawing which shows the blast furnace bosh section structure of the said embodiment. The schematic diagram which shows the design procedure of the blast furnace morning glory part of the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[Overall configuration of blast furnace]
In FIG. 1, a blast furnace 1 has a tubular furnace body 2 constructed on a foundation ground.
The furnace body 2 is divided into a furnace port portion S1, a shaft portion S2, a furnace belly portion S3, a morning glory portion S4, a tuyere portion S5, and a furnace bottom portion S6 sequentially from the upper gas collecting mantel 3. Generally, the inner diameter of the shaft portion S2 expands downward, the inner diameter of the furnace belly portion S3 is the maximum diameter, and the inner diameter of the bosh section S4 decreases downward. The bosh section S4 has a tubular shape, is provided between the tuyere section S5 and the furnace belly section S3, and expands in diameter vertically upward.

In the furnace body 2, a charging device is usually installed in a gas collecting mantel 3, and a granular charging material 4 is charged into the furnace from the charging device. As the charge 4, an ore charge having a particle size of about 8 to 25 mm and a coke charge having a particle size of about 20 to 55 mm are alternately charged in layers. As a result, a massive band 4A in which iron ore and coke are alternately layered is formed in the furnace opening S1 and the shaft S2 in the furnace.
The tuyere 5 is installed in the furnace body 2 above the furnace bottom S6, from which hot air 5A is blown. The hot air 5A causes the coke in the massive band 4A to burn and become hotter, and the raceway 5B (high-speed gas is blown from the tuyere 5 to flow coke in front of the tuyere 5) by hot gas near the tuyere 5. (A space having a high porosity). Due to the high heat of the raceway 5B, the iron ore in the massive band 4A is melted.

The coke combustion and the melting of the iron ore proceed sequentially in the lower part of the massive zone 4A, and a substantially conical fusion zone 4B is formed in the furnace from the bosh section S4 to the lower part of the shaft section S2.
The iron 6A melted in the cohesive zone 4B passes through the dripping zone 4C, drops toward the furnace bottom S6, and accumulates as hot metal 6B in the furnace bottom S6. Coke and the like that have not been completely burned in the cohesive zone 4B pass through the dripping zone 4C and descend, pile up on the furnace bottom S6, and form a conical furnace core 4D on the hot metal 6B.
In the furnace body 2, a tap hole 6 is provided at a furnace bottom portion S <b> 6, and the hot metal 6 </ b> B accumulated in the furnace bottom portion S <b> 6 is taken out of the blast furnace 1 by the tap hole 6.

The furnace body 2 has a steel shell 2A on the outermost periphery, and a cooling stave and a refractory brick 2D are stretched inside the steel shell 2A.
A stave 2B for a shaft is stretched from an upper portion of the shaft portion S2 to a region S7 facing the middle block 4A. In this region S7, since the granular charges 4 contained in the massive band 4A descend sequentially while contacting the surface of the stave 2B, mechanical wear may occur on the surface of the stave 2B.
A stave 2C for a morning glory portion is extended from a lower portion of the shaft portion S2 to an area S8 including a furnace abdomen portion S3 and a morning glory portion S4. In this region S8, a cohesive zone 4B made of the high-temperature charge 4 (a region where the ore in the charge 4 starts to soften and melt, and ores in a semi-molten state are fused to each other and connected in a plate shape). ), The roots 4E descend sequentially while contacting with each other, so that the surface of the stave 2C inside the blast furnace 1 may wear due to high temperature.
Refractory bricks 2D are provided on the furnace inner surfaces of these staves 2B and 2C as needed.
The refractory brick 2E is piled up thickly on the furnace bottom S6 where the hot metal 6B is stored.

[Configuration of morning glory stave]
A morning glory stave 10 as shown in FIG. 2 is used as the morning glory stave 2C installed in the region S8 including the furnace abdomen S3 and the morning glory S4 in FIG.
In FIG. 2, the bosh section stave 10 has a thin plate-shaped stave body 11 cut out from a copper or copper alloy plate material. A plurality of rows of horizontally extending projections 12 are formed on the inner surface of the furnace of the stave body 11, and a recess 13 that is recessed toward the outside of the furnace of the blast furnace 1 is formed therebetween. A refractory 13 </ b> A is fitted in the recess 13.
In the bosh section stave 10, when the bosh section stave 10 is stretched in the furnace, the protrusions 12 at the same height position are continuous with each other. Form a complete torus.
The tip surface of the projection 12 may be coated with a high hardness material such as TiN, TiC, WC, Ti-Al-N, or the like.
The protrusion amount of the protrusion 12 (height from the bottom surface of the recess 13) is 50 to 150 mm (a protrusion amount of about 1 to 3 times the maximum particle diameter of the coke-based charge having a large average particle size of 55 mm), and is adjacent to the protrusion 12. The interval between the projections 12 is about 300 to 1000 mm, more preferably 400 to 700 mm.

In the bosh section stave 10, a cooling pipe (not shown) is formed inside the stave body 11, and a cooling pipe 16 is connected to the back side of the stave body 11. Cooling water from a cooling pipe 16 is passed through a cooling pipe inside the stave body 11. By adjusting the flow rate of the cooling water, the stave body 11 of the bosh section stave 10 and the protrusion 12 having a tip serving as a reference plane are provided. , And the recess 13 are cooled and adjusted to appropriate temperatures.
Such an appropriate cooling promotes the growth of the deposit 7 layer of the charge 4 (see FIG. 3), and the thickness of the deposit 7 layer on the surface of the bosh section stave 10 in the blast furnace 1 is appropriately adjusted. It can be adjusted to a coated state.
The bosh section stave 10 is not limited to a machined product, but may be a casting in which the stave body 11, the protrusion 12 and the recess 13 are collectively cast with copper or a copper alloy.

2, a tuyere cooling box 51, a tuyere nozzle 52, and a tuyere pipe 53 constituting the tuyere 5 are installed in the tuyere part S5.
The tuyere cooling box 51 is a frustoconical cylindrical body that is installed at the opening of the steel shell 2A of the tuyere part S5 and protrudes inside the furnace.
The tuyere nozzle 52 is a conical nozzle formed at the tip of the tuyere pipe 53. The tuyere nozzle 52 is exposed from inside the furnace by inserting the tuyere cooling box 51 from outside the furnace.
The tuyere pipe 53 is supplied with hot air from a hot stove through an annular pipe (not shown), and blows this hot air from the tuyere nozzle 52 into the furnace.

[Blast furnace bosh section structure]
In the present embodiment, a blast furnace bosh section structure 9 according to the present invention is configured in a region S9 extending from the lower part of the furnace belly S3 to the tuyere 5 of the tuyere section S5 via the bosh section S4.
In the region S9, the blast furnace bosh section structure 9 includes a plurality of stages of bosh section staves 10 in the height direction. In the present embodiment, two stages of morning glory staves 10U and 10L are provided above and below the region S9.
The number of staves 10 for the bosh section provided in the blast furnace bosh section structure 9 is not limited to two. For example, three or more staves 10 for the bosh section are arranged between the staves 10U and 10L for the bosh section. You may.

An upper furnace inner surface 19U and a lower furnace inner surface 19L are set on the furnace inner surface of the bosh section stave 10 (10U, 10L) arranged in the region S9.
In addition, when the bosh section staves 10 arranged in the area S9 are, for example, three stages, the section from the upper bosh section stave 10U to the middle height of the middle bosh section stave 10 is defined as the upper furnace inner surface 19U, The section from the intermediate height of the bosh section stave 10 to the lower bosh section stave 10L can be the lower furnace inner surface 19L.
As described above, the upper furnace inner surface 19U and the lower furnace inner surface 19L are surfaces that vertically divide the furnace inner surface side of the region S9 where the blast furnace bosh section structure 9 is installed. However, on the furnace inner surface side of the region S9, there may be a blank portion which does not correspond to the upper furnace inner surface 19U above the upper furnace inner surface 19U, and may be lower than the lower furnace inner surface 19L. There may be a blank portion where the surface 19L does not correspond, and there may be a blank portion between the upper furnace inner surface 19U and the lower furnace inner surface 19L.

Of the bosh section staves 10 arranged in the region S9, the upper bosh section stave 10U is provided with the upper furnace at a position slightly below the upper end of the furnace inner surface (the surface enclosing the tip of the projection 12). An upper reference position PU serving as a reference for the inner surface 19U is set.
The upper reference position PU is a position where the furnace inner surface of the bosh section stave 10 of the furnace abdomen S3 is extended downward, and is located at a height HU from the center height HO of the tuyere nozzle 52. In the present embodiment, the height HU is set to 4300 to 5500 mm.

The portion above the upper reference position PU of the bosh section stave 10U is arranged in the region of the furnace abdomen S3, and the furnace inner surface of that portion is in contact with the furnace inner surface of the bosh section stave 10 installed in the furnace abdomen S3. They are formed on the same surface.
A portion below the upper reference position PU of the bosh section stave 10U is arranged in the bosh section S4 and is an upper furnace inner surface 19U whose furnace surface is inclined with respect to a horizontal plane.
The upper furnace inner surface 19U is constituted by the furnace inner surface of the bosh section stave 10U, and the angle formed by the upper furnace inner surface 19U and the horizontal plane, that is, the upper inclined angle AU is 75 to 82 °, preferably 75 to 78 °. is there.

Among the bosh section staves 10 arranged in the region S9, the lower bosh section stave 10L has an upper end part which constitutes a part of the upper furnace inner surface 19U, but the remaining part is a lower furnace inner surface. 19L.
The lower furnace inner surface 19L is constituted by the furnace inner surface of the bosh section stave 10L (the surface enclosing the tip of the projection 12), and forms an angle between the lower furnace inner surface 19L and a horizontal plane, that is, a lower tilt angle. AL is an angle smaller than the upper furnace inner surface 19U by 2 to 15 °, more preferably 2 to 7 °. Here, a specific value of the lower inclination angle AL is 68 to 75 °, preferably 68 to 72 °. However, the lower inclination angle AL becomes 74 to 75 ° when the upper inclination angle AU is 76 ° or more and 77 ° or more (angle difference 2 to 15 °).

In order to determine the lower furnace inner surface 19L, a lower reference position PL serving as a reference for the lower furnace inner surface 19L is set in the tuyere cooling box 51 of the tuyere 5.
The lower reference position PL is set at a distance EL from the front end position PO of the tuyere cooling box 51 to the outside of the furnace. The distance EL is set in a range of 0 to 300 mm.
When extended, the lower furnace inner surface 19L is formed at a position passing through the lower reference position PL. That is, the lower furnace inner surface 19L can be determined by extending the above-described lower inclination angle AL from the lower reference position PL.

The lower end of the lower bosh section stave 10L is the upper end position of the stave 2C that cools around the tuyere 5. The upper end of the stave 2C that cools the periphery of the tuyere 5 needs to be disposed above the tuyere 5 in order to connect the cooling pipe 16 above the tuyere 5. For this reason, the lower end of the lower bosh section stave 10 </ b> L is installed at an interval from the tuyere 5.
A refractory brick 2D is provided between the lower bosh section stave 10L and the tuyere cooling box 51 of the tuyere 5. The refractory brick 2D installed in this portion is formed so that the surface is continuous with the lower furnace inner surface 19L.
The height of the refractory brick 2D, that is, the distance between the lower bosh section stave 10L and the tuyere cooling box 51 of the tuyere 5 is desirably small. Therefore, the lower morning glory stave 10L may be extended downward so as to approach the tuyere cooling box 51.

[Blast furnace bosh section design method]
The above-described blast furnace bosh section structure 9 of the present embodiment can be simply designed by the following procedure.
As shown in FIG. 3, an upper furnace inner surface 19 </ b> U and a lower furnace inner surface 19 </ b> L are set on the furnace inner surface of the bosh section stave 10 constituting the blast furnace bosh section structure 9.

As a reference of the upper furnace inner surface 19U, first, a reference of the furnace inner surface of the bosh section stave 10 which is located above the center height HO of the tuyere nozzle 52 by a predetermined height HU and is disposed in the furnace abdomen S3. The upper reference position PU is set at a position where the surface RS extends downward.
Next, an upper reference plane RU having an inclination angle of 75 to 82 ° with respect to a horizontal plane is set downward and inside the furnace from the upper reference position PU.

As a reference of the lower furnace inner surface 19L, first, a lower reference position PL is set at a position of a predetermined distance EL from the furnace inner end position PO of the tuyere cooling box 51 to the furnace outer side.
Next, from the lower reference position PL to the upper side of the furnace, the lower reference plane RL whose inclination angle with respect to the horizontal plane is smaller than the inclination angle of the upper reference plane 19U with respect to the horizontal plane by 2 to 15 ° (for example, 68 to 75 °) is set. Set.

When the upper reference plane RU and the lower reference plane RL are obtained, a position where these two planes intersect is defined as an intersection position PC.
Then, an upper furnace inner surface 19U is formed above the morning glory stave 10U or the morning glory stave 10L within the range of the intersection position PC from the upper reference plane RU along the upper reference plane RU.
Further, a lower furnace inner surface 19L is formed on the bosh section stave 10L in a range of the intersection position PC from the lower reference plane RL along the lower reference plane RL.
As described above, the upper furnace inner surface 19U and the lower furnace inner surface 19L having a predetermined inclination can be easily formed.

[Function and effect of the blast furnace bosh section]
According to the blast furnace bosh section structure 9 of the present embodiment, of the furnace inner surfaces of the bosh section staves 10U and 10L, the upper furnace inner surface 19U has an inclination angle of 75 to 82 ° with respect to the horizontal plane, so that an appropriate angle is obtained. The generation of deposits in the furnace can be realized, and the furnace surface profile including the circumferential balance can be stabilized.
On the other hand, in the lower furnace inner surface 19L, the inclination angle with respect to the horizontal plane is set to an angle smaller than the inclination angle of the upper furnace inner surface 19U with respect to the horizontal plane by 2 to 15 °, so that the inclination becomes more gentle than the upper furnace inner surface 19U. Thus, the accumulation of deposits directly above the tuyere 5 can be positively induced.

  Thereby, the tuyere 5 can be sufficiently protected by the bosh section stave 10L and the deposits on the surface thereof. As a result, it is no longer necessary to install a refractory brick having a conventional thickness between the bosh section stave 10L and the tuyere 5, and the furnace inner surface profile including the circumferential balance can be stabilized immediately above the tuyere 5. Can be achieved.

In the present embodiment, sufficient protection performance can be obtained for the tuyere cooling box 51 of the tuyere 5 by the bosh section stave 10L having the lower furnace inner surface 19L and the attached matter.
In particular, since the lower reference position PL is set in the tuyere cooling box 51, the tuyere cooling box 51 can be widely covered within a range that does not affect the blowing of the tuyere 5, and the protection for the tuyere cooling box 51 is ensured. Can be

  In the present embodiment, by setting the height HU of the upper edge position of the bosh section stove 10U in the above-described range, the height position of the root portion of the cohesive zone of the charge is changed due to a change in the operation state of the blast furnace 1. Even if it fluctuates, the bosh section staves 10U, 10L are arranged above the tuyere S5 at an appropriate inclination angle (the above-described inclination angles AL, AU of the lower furnace inner surface 19L and the upper furnace inner surface 19U). By setting the vertical dimension from the center HO of the tuyere 5 to the upper edge position of the bosh section S4 to a sufficient length, the root of the cohesive zone can be stably supported.

(Modification)
Note that the present invention is not limited to the configuration of the above-described embodiment, and modifications and the like within a range that can achieve the object of the present invention are included in the present invention.
As described above, the bosh section staves 10 arranged in the area S9 to form the blast furnace bosh section structure 9 may be installed in two or more stages, or in three or more stages. Usually, a plurality of steps are required to cover the area S9, that is, the area including the morning glory S4 and up to the center of the tuyere 5, but only one stave may be used.

As described above, the upper furnace inner surface 19U and the lower furnace inner surface 19L are not fixedly set to each of the bosh section staves 10U and 10L, and are not fixed to the bosh section stave 10 arranged in the region S9. It can be set separately from the boundary.
Further, the upper and lower furnace inner surfaces 19U and 19L are provided with upper and lower and middle surfaces of the inner surface of the furnace where appropriate, ie, a blank region, that is, a furnace inner surface having a shape deviating from the conditions of the upper and lower furnace inner surfaces 19U and 19L. Is also good.
In short, the upper furnace inner surface 19U and the lower furnace inner surface 19L are vertically arranged in the region S9 to be the blast furnace bosh section structure 9, and the total area of the upper furnace inner surface 19U and the lower furnace inner surface 19L is equal to the entire region S9. 80% or more of the area.

The inclination angles AU and AL of the upper furnace inner surface 19U and the lower furnace inner surface 19L may both be 75 °. In this case, the upper furnace inner surface 19U and the lower furnace inner surface 19L are continuous on the same surface.
However, due to the function of accelerating the formation of deposits immediately above the tuyere 5, the inclination angle AL of the lower furnace inner surface 19L is smaller than the inclination angle AU of the upper furnace inner surface 19U (to be gentler). ) Is desirable.

The height of the intersection position PC between the upper furnace inner surface 19U and the lower furnace inner surface 19L, or the horizontal position between the lower reference position PL and the upper reference position PU is within a range in which the configuration of the present invention can be secured. It is not particularly limited as long as it is within the range, and is appropriately set based on the furnace inside tip position PO of the tuyere cooling box 51, the upper reference position PU of the upper furnace inner surface 19U, the positional relationship between the respective parts of the blast furnace, and the like. Can be.
In addition, in the blast furnace bosh section structure 9 or the blast furnace 1, each material quality, detailed shape, and the like can be appropriately selected in practice.

  INDUSTRIAL APPLICABILITY The present invention can be used for a blast furnace bosh section structure and a blast furnace design method.

  DESCRIPTION OF SYMBOLS 1 ... Blast furnace, 10, 10L, 10U ... Stave for morning glory, 11 ... Stave body, 12 ... Protrusion, 13 ... Recess, 13A ... Refractory, 16 ... Cooling pipe, 19L ... Lower furnace inner surface, 19U ... Upper furnace inner surface, 2 ... furnace body, 2A ... steel, 2B ... stave, 2C ... stave, 2D ... fire brick, 2E ... fire brick, 3 ... gas collecting mantel, 4 ... charged material, 4A ... mass band , 4B: fusion zone, 4C: drip zone, 4D: furnace core, 4E: root, 5: tuyere, 51: tuyere cooling box, 52: tuyere nozzle, 53: tuyere piping, 5A: hot air, 5B ... Raceway, 6 ... Tap hole, 6A ... Iron, 6B ... Hot metal, 9 ... Blast furnace bosh section, AL ... Lower slope angle, AU ... Lower slope angle, EL ... Distance from the tip of the tuyere cooling box, HO: Tuyere center, PC: Intersection position, PL: Lower reference position, PO: Furnace inner tip position, PU ... Side reference position, RL: lower reference plane, RU: upper reference plane, RS: reference plane of the inner surface of the furnace belly, S1: furnace mouth, S2: shaft, S3: furnace belly, S4: morning glory, S5: Tuyere, S6: Furnace bottom, S7, S8: Area, S9: Blast furnace bosh section structure installation area.

Claims (4)

A blast furnace bosh section structure that is provided between the tuyere part of the blast furnace and the abdomen of the furnace and constitutes a tubular bosh section that expands in diameter vertically upward,
The bosh section includes an annular steel shell, a copper or copper alloy bosh section stave provided on the inner periphery of the steel shell, and a firebrick provided on the inner periphery of the bosh section stave. And
A tuyere cooling box capable of inserting a tuyere nozzle from the outside of the furnace is installed below the bosh section,
An upper furnace inner surface and a lower furnace inner surface are formed on a furnace inner surface of the bosh section stave,
The upper furnace inner surface has an inclination angle of 75 to 82 ° with respect to a horizontal plane,
The blast furnace bosh section structure, wherein an inclination angle of the lower furnace inner surface with respect to a horizontal plane is smaller than an inclination angle of the upper furnace inner surface with respect to a horizontal plane by 2 to 15 °. The blast furnace bosh section structure according to claim 1,
The blast furnace bosh section structure, wherein the lower furnace inner surface is located at a position extending from the inner end of the tuyere cooling box to the outer side of the furnace at a distance of 0 to 300 mm when extended. In the blast furnace bosh section structure according to claim 1 or claim 2,
The blast furnace bosh section structure, wherein an upper end of the upper furnace inner surface is arranged at 4300 to 5500 mm from a center height of the tuyere nozzle. A tuyere portion, a furnace belly portion, and a tubular bosh section provided between the tuyere portion and the furnace belly portion and having a diameter that increases in a vertical upward direction, wherein the bosh section is an annular steel bar, A copper or copper alloy bosh section stave provided on the inner periphery of the steel shell, and a firebrick provided on the inner periphery of the bosh section stave, and a tuyere nozzle, A method for designing a blast furnace having a tuyere cooling box insertable from outside the furnace,
On the furnace inner surface of the bosh section stave, the upper furnace inner surface and the lower furnace inner surface are arranged,
The upper reference position is set at a position above the center height of the tuyere nozzle and at a predetermined height above the furnace inner surface of the stave arranged at the furnace belly, extending downward.
Forming the upper furnace inner surface along an upper reference plane having an inclination angle of 75 to 82 ° with respect to a horizontal plane, from the upper reference position downward and inside the furnace,
A lower reference position is set at a position at a predetermined distance from the furnace inside tip of the tuyere cooling box to the furnace outside,
Forming the lower furnace inner surface along a lower reference plane whose inclination angle with respect to a horizontal plane is 2 to 15 ° smaller than the inclination angle of the upper reference plane with respect to the horizontal plane, from the lower reference position upward and outside the furnace. A blast furnace design method characterized by the following.

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