JP2016065306A - Furnace bottom structure of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the externally lining material of a carbonaceous brick by leaving the lining material of an oxide-based brick even after operation in the side wall part of the furnace bottom structure in a blast furnace.SOLUTION: In the furnace bottom 10 of a blast furnace in which an annular side wall part 30 is provided on a platy hearth part 20, the side wall part 30 comprises an externally lined carbonaceous brick 31 and an oxide-based brick 32 internally lined inside the carbonaceous brick 31. When the thermal conductivity of the oxide-based brick 32 is a critical thermal conductivity or less, the thickness of the brick 32 is set to a prescribed thickness. When the thermal conductivity of the brick 32 is higher than the critical one, the thickness of the brick 32 is thicker than the prescribed thickness and is set based on the thermal conductivity of the carbonaceous brick 31 and that of the oxide-based brick 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bottom structure of a blast furnace, and more specifically, to a bottom refractory structure of a blast furnace in which a refractory is lined to store a high-temperature metal melt.

  Furnace bottom refractories in blast furnaces, electric furnaces, or furnaces lined with refractories to store high-temperature metal melts similar to these (in the following explanation, “blast furnace” is used as an example) It is exposed to the flow of water and gradually erodes in the process of long-term operation. On the other hand, once the operation of the furnace bottom of the blast furnace is started by firing, it is technically difficult to repair such as transshipment during the subsequent operation period. For this reason, in order to extend the life of the bottom of the blast furnace, there is actually no choice but to deal with it by performing operations that can mitigate the progress of erosion.

  As in recent years, the life (operation period) of the blast furnace reaches 20 years or more, or in order to achieve a life longer than that, it is necessary to accurately estimate the erosion line at the bottom of the blast furnace, It has become more important than ever to employ a bottom structure that can effectively mitigate the progress of erosion based on estimation results.

  Conventionally, the erosion line at the bottom of the blast furnace is based on the temperature and distance between two points and the bottom of the furnace between them based on the thermocouples embedded in the refractory of the blast furnace that is actually in operation. The heat flux is calculated from the thermal conductivity of the brick, and is estimated by a method of calculating the remaining thickness assuming that the temperature of the working surface in the furnace is the wear limit temperature of the material.

  Patent Document 1 discloses a method of calculating the remaining thickness of the bottom brick by performing a heat transfer analysis by a boundary element method using temperature measurement values around a furnace body as a constraint.

  All of these methods for estimating the bottom erosion line use the measured temperature data to determine the current bottom erosion line and estimate the tendency of subsequent erosion based on the obtained erosion data. Is. It is not possible to predict how far the bottom brick erosion will progress before the start of operation by fire.

  If the flow of hot metal at the bottom of the furnace, the heat transfer phenomenon in the region including the brick, and the wear conditions of the brick are clear, a mathematical model describing them will be constructed, and if these are solved in time, The time transition of the wear line of bricks can be estimated. Based on this idea, the present applicant previously solved the material balance, momentum balance, and energy balance of the entire furnace bottom in Patent Document 2 and determined erosion based on the erosion limit temperature of the brick. The furnace bottom erosion line was estimated before the start of operation by fire. And the furnace bottom structure which can suppress the erosion of a furnace bottom brick as much as possible was disclosed.

  Specifically, the method according to the patent invention disclosed by Patent Document 2 includes: (a) generating an initial structure of a bottom brick and generating a lattice; (b) molten iron melted in a brick-lined furnace. Calculating the temperature distribution of bricks and the flow and temperature distribution of hot metal on the bottom of the furnace based on the mass balance equation, momentum balance equation, and energy balance equation of the entire region including brick, (c ) Determining the temperature distribution of each grid as time progresses, (d) Determining that the bricks of the grid exceeding the limit temperature of the bricks are worn based on the calculated temperature distribution, (e) Wear (F) Replacing the brick determined to have occurred with hot metal, (f) Repeating the above operations (c) to (e) until the brick wear stops, the background and the wear loss of the bottom brick. Line and push To be a furnace bottom estimating method of erosion lines consisting of.

  As described above, the method disclosed in Patent Document 2 repeats the calculation of the bottom erosion line until the bottom brick erosion stops, so that the background of the bottom brick erosion and the equilibrium wear line are fired. It becomes possible to predict before the start of operation.

  In addition, in the patent document 3, the inventors reflect the lower end level of the core coke accompanying the furnace bottom brick erosion and the shape thereof in the evaluation, thereby improving the prediction accuracy with respect to the patent document 2. The estimation method of erosion line is given. Further, Patent Document 3 shows a furnace bottom structure in which a carbonaceous brick having a thickness set by using this estimation method is used as an outer covering material, and a clay brick is used as an inner covering material.

  Further, Patent Document 4 proposes a furnace bottom structure in which a carbonaceous brick is used as an outer lining and a clay brick is used as a lining in a ceramic bottom lining of a blast furnace hearth.

JP-A-60-184606 Japanese Patent No. 3385831 Japanese Patent No. 5381892 Special table 2014-501328 specification

  However, in the above-described invention, a design guideline is given for the structure of the bottom of the clay brick in which the carbonaceous brick is used as the outer material and the clay brick is used as the inner material. It is not a thing.

  The object of the present invention is to leave the oxide-based brick lining material after the start-up operation of the blast furnace at the side wall portion of the furnace bottom structure using the carbonaceous brick as the outer material and the oxide-based brick as the lining material. It is to present requirements for the lining of oxide bricks, which can protect the outer material of carbonaceous bricks.

  The inventors of the present invention have used the method of estimating the bottom erosion line described in Patent Document 3 to use a carbonaceous brick as an outer covering material and an oxide brick as a lining material in a side wall portion of the furnace bottom structure. The equilibrium wear line was calculated over a wide range of conditions. As a result, the inventors have found requirements for oxide bricks to leave the lining material. In addition, the oxide brick of this invention includes what is called a clay-type brick so that it may mention later.

  Specifically, it was found that there is a critical value of the thermal conductivity of oxide bricks that does not wear the oxide bricks until the thermal equilibrium is reached at the furnace bottom after the blast furnace is started. That is, when the thermal conductivity of the oxide brick is equal to or less than the above critical value, the oxide brick does not wear and remains at a predetermined predetermined thickness.

  In addition, when the thermal conductivity of the oxide brick exceeds the critical value, it was found that the limit thickness of the oxide brick can be defined by the thermal conductivity of the carbon brick and the thermal conductivity of the oxide brick. . The limit thickness of the oxide brick is a limit thickness at which the oxide brick is worn and becomes zero when the furnace bottom is in thermal equilibrium, and the carbon brick is not eroded. And if the thickness (initial thickness at the time of starting of a blast furnace) of an oxide type brick is set more than the said limit thickness, an oxide type brick can be made to remain.

  Based on such knowledge, the present invention provides a furnace bottom structure of a blast furnace in which an annular side wall is provided on a plate-shaped hearth, and the side wall includes an outer carbon-based brick, It comprises an oxide brick lined on the inside of the carbonaceous brick, and when the thermal conductivity of the oxide brick is equal to or lower than the critical thermal conductivity, the thickness of the oxide brick is set to a predetermined thickness, When the thermal conductivity of the oxide brick is larger than the critical thermal conductivity, the thickness of the oxide brick is larger than the predetermined thickness, and the thermal conductivity of the carbonaceous brick and the oxide brick. It is characterized in that it is set based on the thermal conductivity.

  In addition, when the thermal conductivity of the oxide brick is larger than the critical thermal conductivity, the critical thickness of the oxide brick that does not erode the carbon brick is set as an objective variable, and the thermal conductivity of the carbon brick. The thickness of the oxide brick may be set using a regression equation that includes the rate and the thermal conductivity of the oxide brick as explanatory variables. Furthermore, as the thermal conductivity of the oxide brick becomes larger than the critical thermal conductivity, the thickness of the oxide brick may be set larger.

  In addition, the present inventors have found that the critical thermal conductivity increases as the thermal conductivity of the carbonaceous brick increases.

  The upper end position of the side wall portion may coincide with the lower end position of the tap hole.

  Furthermore, the present inventors use the furnace bottom erosion line estimation method described in Patent Document 3 to lay a clay-based brick as a lining material with respect to a carbonaceous brick as a lining material. In terms of the equilibrium wear line was calculated over a wide range of conditions. As a result, the present inventors have found requirements regarding the laying area of oxide bricks for leaving carbonaceous bricks and oxide bricks. Specifically, it has been found that the necessary laying region for the oxide-based brick is a region having a central angle in plan view of 30 degrees or less starting from the center of the taphole in the side wall portion.

  According to the present invention, it is possible to leave the oxide brick of the lining material even in a stable operation state after the blast furnace is started up, and it is possible to prevent the carbonaceous brick of the outer material from being melted. Further, the thickness of the oxide brick is minimized, and the carbonaceous brick has the maximum furnace bottom structure, so that the furnace bottom structure having the best cooling capacity is obtained.

It is explanatory drawing of the longitudinal cross-section which shows the furnace bottom structure of the blast furnace concerning this Embodiment. It is a simulation result in case the thermal conductivity of a carbonaceous brick is 18.0 kcal / mh ° C., and shows the remaining thickness of the oxide brick with respect to the initial thickness of the oxide brick. It is a simulation result in case the heat conductivity of a carbonaceous brick is 23.0 kcal / mh degreeC, and shows the residual thickness of the oxide brick with respect to the initial thickness of an oxide brick. It is a simulation result in case the thermal conductivity of a carbonaceous brick is 28.4 kcal / mh degree C, and shows the remaining thickness of the oxide brick with respect to the initial thickness of the oxide brick. It is a simulation result at the time of fluctuating the thermal conductivity of a carbonaceous brick, and shows the limit thickness of an oxide brick with respect to the thermal conductivity of an oxide brick. It is explanatory drawing of the longitudinal cross-section which shows the furnace bottom structure of the blast furnace concerning other embodiment. It is explanatory drawing of the cross section which shows the furnace bottom structure of the blast furnace concerning other embodiment. It is a simulation result at the time of changing the laying area | region of an oxide type brick, and shows the relationship between the center angle of the laying area | region of the said oxide type brick, and the total remaining thickness of the brick of a hearth part. It is a simulation result at the time of fluctuating the laying area | region of an oxide type brick, and shows the total remaining thickness of the brick in the circumferential direction (angle from a taphole direction) of a side wall part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1. Blast furnace bottom structure>
FIG. 1 is an explanatory diagram showing a blast furnace bottom structure according to the present embodiment. A furnace bottom 10 of the blast furnace includes a hearth part 20 and a side wall part 30. A dotted line in FIG. 1 indicates a boundary line between the hearth portion 20 and the side wall portion 30.

  The hearth part 20 is provided in a flat plate shape on the bottom surface of the furnace bottom 10. The hearth part 20 includes a carbonaceous brick 21 that is externally stretched on the bottom side of the furnace floor, and an oxide brick 22 that is a lining material that is lined inside the carbonaceous brick 21. .

  The side wall part 30 is provided in an annular shape on the outer peripheral part of the hearth part 20. The lower end of the side wall part 30 is located on the upper surface of the hearth part 20, and the upper end of the side wall part 30 is located at the lower end of the tap hole 40. The side wall portion 30 includes a carbonaceous brick 31 that is externally stretched on the iron skin side, and an oxide brick 32 that is a lining material that is lined inside the carbonaceous brick 31.

  The carbonaceous bricks 21 and 31 are made of a carbonaceous material such as natural graphite, artificial graphite, coke, anthracite, or the like as a main raw material, and bricks manufactured using a binding material such as tar and pitch, and clay-like bricks. It is a general term for bricks made by blending raw materials with graphite.

The oxide bricks 22 and 32 include clay bricks in addition to oxide bricks such as ASC bricks (Al ₂ O ₃ —SiC—C). Clay-based brick is a general term for refractory bricks whose main raw material is a refractory raw material having a similar chemical composition, such as refractory clay or wax.

<2. Requirements for oxide bricks on side walls>
In the side wall 30, the initial thickness Lce of the oxide brick 32 at the time of starting up the blast furnace is constant in the vertical direction (Z-axis direction in FIG. 1). The thickness Lce of the oxide brick 32 is set by the following equation (1).

ここで、
k₁=1.04-0.0205λca
k₂=2.59-0.0869λca+0.00201λca²
k₃=2.01-0.0386λca
Ｌce：酸化物系レンガ３２の厚み（ｍ）
λca：カーボン質系レンガ３１の熱伝導率（ｋｃａｌ／ｍｈ℃）
λce：酸化物系レンガ３２の熱伝導率（ｋｃａｌ／ｍｈ℃）
但し、max[a, b, c,…]は、a, b, c,…の中の最大の要素をあらわす。

here,
k ₁ = 1.04-0.0205λca
k ₂ = 2.59-0.0869λca + 0.00201λca ²
k ₃ = 2.01-0.0386λca
Lce: thickness of oxide brick 32 (m)
λca: thermal conductivity of carbonaceous brick 31 (kcal / mh ° C.)
λce: thermal conductivity of oxide brick 32 (kcal / mh ° C.)
However, max [a, b, c,...] Represents the maximum element in a, b, c,.

  The necessary requirement of the oxide brick 32 set by the above equation (1) is that the oxide brick at the time when thermal equilibrium is achieved at the furnace bottom 10 (corresponding to the time when the blast furnace starts up and shifts to stable operation). The limit thickness of the brick 32 is derived from the results of studying various cases. In other words, the expression (1) was derived based on the following two findings obtained by the inventors. Details of the derivation of equation (1) will be described in the first embodiment.

  The first finding is that there is a critical thermal conductivity λce-critical of the thermal conductivity λce of the oxide brick 32 so that the oxide brick 32 does not wear during the blast furnace startup. That is, when the thermal conductivity λce of the oxide brick 32 is less than or equal to the critical thermal conductivity λce-critical, the oxide brick 32 does not wear and remains with a predetermined thickness set initially. In the present embodiment, the predetermined thickness is 0.1 m, but this predetermined thickness can be arbitrarily set. The predetermined thickness is set to a minimum thickness required for actual operation of the blast furnace, for example.

  The second finding is that when the thermal conductivity λce of the oxide brick 32 exceeds the critical thermal conductivity λce-critical, the limit thickness of the oxide brick 32 is set to the thermal conductivity λca of the carbonaceous brick 31 and It can be defined by the thermal conductivity λce of the oxide brick 32. The limit thickness of the oxide brick 32 is the minimum value of the initial thickness of the oxide brick 32 at which the oxide brick 32 is worn and becomes zero when the furnace bottom 10 is in thermal equilibrium. If the thickness Lce of the oxide brick 32 is set to be equal to or greater than the above-mentioned limit thickness, the oxide brick 32 can be left during thermal equilibrium, and the carbonaceous brick 31 is not eroded.

  From the above, when the thermal conductivity λce of the oxide brick 32 is less than or equal to the critical thermal conductivity λce-critical, the minimum value of the thickness Lce of the oxide brick 32 is set in the right term within the max in the equation (1). Is done. On the other hand, when the thermal conductivity λce of the oxide-based brick 32 is larger than the critical thermal conductivity λce-critical, the minimum value of the thickness Lce of the oxide-based brick 32 is set in the left term within the max in the equation (1). The

  In other words, when the thermal conductivity λce of the oxide brick 32 is small, the thickness Lce of the oxide brick 32 can be reduced. As will be described later, as the thermal conductivity λca of the carbonaceous brick 31 increases, the critical thermal conductivity λce-critical increases. For this reason, when the thermal conductivity λca of the carbonaceous brick 31 is large, the thickness Lce of the oxide brick 32 can be reduced.

<3. Adjustment method for thermal conductivity of carbonaceous brick and oxide brick>
Generally, a carbonaceous brick 31 having a high thermal conductivity is used for the side wall portion 30 of the bottom 10 of the blast furnace in order to effectively function the cooling and protect the portion. Since the possibility of erosion increases when the carbonaceous brick 31 is in direct contact with the hot metal, the present inventors appropriately put an oxide brick 32 having an appropriate thermal conductivity between the hot metal and the carbonaceous brick 31. It recalled that the carbonaceous brick 31 can be protected by interposing in thickness. Even in this case, from the viewpoint of cooling protection, it is usually preferable to make the carbonaceous brick 31 thick and the oxide brick 32 thin.

Here, the thermal conductivity λca of the carbonaceous brick 31 and the thermal conductivity λce of the oxide brick 32 can be controlled by changing the raw material, the molding method, and the firing method. However, the oxide brick 32 that protects the carbonaceous brick 31 of the side wall portion 30 is required not only to control the amount of heat transfer but also to the hot metal and the corrosion resistance against hot metal. Here, the hot metal and the corrosion resistance of the brick to the hot metal are resistance to the hot metal and chemical action by the hot metal, and can be controlled by changing the components of the brick. Therefore, bricks having a low thermal conductivity λce and high corrosion resistance, for example, ASC bricks (Al ₂ O ₃ —SiC—C) are used for the oxide bricks 32.

  As described above, the combination of the carbonaceous brick 31 having a large thermal conductivity λca and the oxide brick 32 having a small thermal conductivity λce is appropriately selected from the viewpoints of thermal conductivity, corrosion resistance to cocoons, cost, and the like. And by determining the thickness of the oxide brick 32 based on this invention, in the arbitrary combination of the carbonaceous brick 31 and the oxide brick 32, the thickness of the oxide brick 32 is made minimum necessary. be able to. On the other hand, since the thickness of the carbonaceous brick 31 can be ensured to the maximum, a furnace bottom structure with the best cooling capacity can be realized.

<4. Laying area of oxide brick on side wall>
The requirement for the oxide brick 32 described above is a requirement that is necessary at a location where the speed of the hot metal flow in the vicinity of the tap outlet 40 is high. On the other hand, in the region away from the spout 40, the hot metal flow rate is reduced, so the requirements for the oxide brick 32 can be relaxed. Therefore, the present inventors have studied the requirements of the oxide brick 32 in the circumferential direction of the side wall portion 30 and have derived a necessary laying region of the oxide brick 32.

  Specifically, as shown in FIGS. 6 and 7, the necessary laying region of the oxide-based brick 32 is horizontal in the side wall portion 30 where the central angle θce in a plan view starts from the center 40 c of the spout 40. It is an area within 30 degrees on both sides. In other words, in the region where the central angle θce is larger than 30 degrees from the center 40c of the tap 40, it is only necessary to provide the carbonaceous brick 31 in the side wall portion 30, and it is not necessary to provide the oxide brick 32. . The reason why the threshold value of the required laying region of the oxide brick 32, that is, the central angle θce is 30 degrees will be described in the second embodiment.

  In such a case, the oxide brick 32 provided in the necessary laying area satisfies the above-described requirements, and it is possible to leave the oxide brick 32 of the lining material even in a stable operation state after the blast furnace is started up. Thus, it is possible to prevent the carbonaceous brick 31 as the outer material from being melted. In addition, since the expensive oxide brick 32 is laid only in the necessary area, the life of the blast furnace can be extended more economically.

  Hereinafter, the result of the heat transfer simulation at the bottom of the blast furnace that has led to the present invention will be described.

In the heat transfer simulation, the furnace bottom erosion line estimation method described in Patent Document 3 was used. And based on the said estimation method, various structures of the side wall part 30 of the furnace bottom 10 which uses the carbonaceous brick 31 as an outer material and the oxide brick 32 as an inner material in a blast furnace having a furnace volume of 5500 m ³ class are set. The amount of equilibrium wear of the carbonaceous brick 31 and the oxide brick 32 estimated in this case was evaluated. Table 1 shows the conditions regarding the thickness Lce of the carbonaceous brick 31 and the thickness Lca of the oxide brick 32, Table 2 shows the conditions regarding the thermal conductivity λce of the oxide brick 32, and Table 3 shows other conditions.

  The results of the heat transfer simulation are shown in FIGS. FIG. 2 shows a simulation result when the thermal conductivity λca of the carbonaceous brick 31 is 18.0 kcal / mh ° C., and FIG. 3 shows a case where the thermal conductivity λca of the carbonaceous brick 31 is 23.0 kcal / mh ° C. FIG. 4 shows the simulation result when the thermal conductivity λca of the carbonaceous brick 31 is 28.4 kcal / mh ° C.

  2 to 4, six graphs (a) to (f) of Cases 1 to 6 in which the thermal conductivity λce of the oxide brick 32 is changed as shown in Table 2 are shown. 2 to 4, the horizontal axis represents the initial thickness Lce of the oxide brick 32 shown in Table 1, and the vertical axis represents the remaining oxide brick 32. It is thickness. A solid line in the graph indicates a boundary line between the oxide brick 32 and the carbonaceous brick 31 when the furnace bottom 10 is in thermal equilibrium.

Referring to FIGS. 2 to 4, the following was found.
(1) If there is an oxide brick 32 having a certain thickness, the carbonaceous brick 31 can be protected.
(2) Even if the initial thickness Lce of the oxide brick 32 is excessive, the oxide brick 32 remains only at a substantially constant level during thermal equilibrium.
(3) The larger the thermal conductivity λce of the oxide brick 32, the more easily the oxide brick 32 is eroded. When the initial thickness Lce of the oxide brick 32 is less than a certain value, the carbonaceous It is estimated that erosion proceeds to the brick 31.
(4) The amount of equilibrium wear of the oxide brick 32 also depends on the thermal conductivity λca of the carbonaceous brick 31, and the thermal conductivity of the oxide brick 32 increases as the thermal conductivity λca of the carbonaceous brick 31 increases. λce can be relaxed to a larger value.

  FIG. 5 summarizes each graph in FIGS. That is, in each graph (a) to (c) of FIG. 5, the thermal conductivity λca of the carbonaceous brick 31 varies to 18.0 kcal / mh ° C., 23.0 kcal / mh ° C., and 28.4 kcal / mh ° C., respectively. A graph is shown. In each graph (a) to (c) in FIG. 5, the horizontal axis is the thermal conductivity λce of the oxide brick 32, and the vertical axis is the limit thickness (required lower limit thickness) of the oxide brick 32. .

Referring to FIG. 5, the following was found.
(1) There is a critical thermal conductivity λce-critical of the oxide brick 32 with which the oxide brick 32 does not wear at all with respect to the carbonaceous brick 31 having various thermal conductivities λca.
(2) The oxide brick 32 having a thermal conductivity λce equal to or lower than the critical thermal conductivity λce-critical can be set to a practical minimum value of 0.1 m.
(3) In the oxide brick 32 that exceeds the critical thermal conductivity λce-critical, it is necessary to increase the thickness of the oxide brick 32 as the thermal conductivity λce of the oxide brick 32 increases.
(4) As the thermal conductivity λca of the carbonaceous brick 31 increases, the critical thermal conductivity λce-critical can be relaxed to the larger side.

  Then, when the relationship shown in FIG. 5 is formulated, the above-described equation (1) is derived. That is, when the thermal conductivity λce of the oxide brick 32 is less than or equal to the critical thermal conductivity λce-critical, the thickness of the oxide brick 32 can be 0.1 m. When the thermal conductivity λce of the oxide brick 32 is larger than the critical thermal conductivity λce-critical, the graph of FIG. A regression equation including the thermal conductivity λca of the brick 31 and the thermal conductivity λce of the oxide brick 32 as explanatory variables was derived. Then, the minimum value of the thickness Lce of the oxide brick 32, that is, the right side of the equation (1), which can leave the oxide brick 32 even when the furnace bottom 10 is in thermal equilibrium, was derived.

  Note that the regression analysis method when the thermal conductivity λce of the oxide brick 32 is larger than the critical thermal conductivity λce-critical is not limited to the above, and various regression equations can be derived.

  Next, the result of the heat transfer simulation regarding the necessary laying region of the oxide brick 32 described above will be described.

In the heat transfer simulation, the furnace bottom erosion line estimation method described in Patent Document 3 was used. And based on the said estimation method, various structures of the side wall part 30 of the furnace bottom 10 which uses the carbonaceous brick 31 as an outer material and the oxide brick 32 as an inner material in a blast furnace having a furnace volume of 5500 m ³ class are set. The estimated amount of equilibrium wear was evaluated. Table 4 shows conditions regarding the laying region of the oxide brick 32 (center angle θce of the laying region), and Table 5 shows other conditions. Here, in view of safety in design, the output ratio is 3.0 t / d. An output amount equivalent to m ³ was assumed.

  The results of the heat transfer simulation are shown in FIGS. FIG. 8 shows the relationship between the central angle θce of the laying region of the oxide brick 32 that is the lining material and the total remaining thickness of the bricks 21 and 22 in the hearth part 20. The total remaining thickness shown in the figure indicates the total thickness of the carbonaceous brick 21 and the oxide brick 22. Referring to FIG. 8, when the central angle θce of the laying region of the oxide brick 32 is smaller than 30 degrees starting from the center 40 c of the taphole 40, the remaining thickness of the bricks 21 and 22 of the hearth portion 20 is small. I understand that

  FIG. 9 shows the total remaining thickness of the bricks 31 and 32 in the circumferential direction of the side wall portion 30. Specifically, for Cases 1 to 6, the thickness of the carbonaceous brick 31 and the oxide brick 32 at a position from the center 40c of the taphole 40 (described as an angle from the taphole orientation in FIG. 9). The total thickness (total remaining thickness) is shown. Referring to FIG. 9, when the central angle θce of the laying region of the oxide brick 32 is smaller than 30 degrees starting from the center 40 c of the taphole 40, the total remaining thickness of the bricks 31 and 32 on the side wall 30 is small. I understand that

  From the above results, in the structure of the side wall portion 30 of the furnace bottom 10 in which the carbonaceous brick 31 is used as the outer covering material and the oxide brick 32 is used as the inner covering material, the necessary laying region of the oxide brick 32 is seen in a plan view. It has been found that the central angle θce at is a region within 30 degrees on both sides in the horizontal direction starting from the center 40c of the tap 40.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

  INDUSTRIAL APPLICABILITY The present invention is useful when installing a side wall portion in which a carbonaceous brick is used as an outer material and an oxide brick is used as an inner material in a blast furnace bottom structure.

DESCRIPTION OF SYMBOLS 10 Furnace bottom 20 Hearth part 21 Carbonaceous brick 22 Oxide brick 30 Side wall part 31 Carbonaceous brick 32 Oxide brick 40 Outlet

Claims (6)

In the blast furnace bottom structure in which an annular side wall is provided on a plate-shaped hearth,
The side wall includes a carbonaceous brick that is lined outside, and an oxide brick that is lined inside the carbonaceous brick,
If the thermal conductivity of the oxide brick is less than or equal to the critical thermal conductivity, the thickness of the oxide brick is set to a predetermined thickness,
When the thermal conductivity of the oxide brick is larger than the critical thermal conductivity, the thickness of the oxide brick is larger than the predetermined thickness, and the thermal conductivity of the carbonaceous brick and the oxide brick. A bottom structure of a blast furnace, which is set based on the thermal conductivity of the blast furnace. When the thermal conductivity of the oxide brick is larger than the critical thermal conductivity, the critical thickness of the oxide brick that does not erode the carbonaceous brick is a target variable, and the thermal conductivity of the carbon brick is The furnace bottom structure of a blast furnace according to claim 1, wherein the thickness of the oxide brick is set using a regression equation including the thermal conductivity of the oxide brick as an explanatory variable. The bottom structure of a blast furnace according to claim 2, wherein the thickness of the oxide brick is set to be larger as the thermal conductivity of the oxide brick becomes larger than the critical thermal conductivity. . The blast furnace bottom structure according to any one of claims 1 to 3, wherein the critical thermal conductivity increases as the thermal conductivity of the carbonaceous brick increases. The bottom structure of a blast furnace according to any one of claims 1 to 4, wherein an upper end position of the side wall portion coincides with a lower end position of the tap hole. 6. The oxide brick according to claim 1, wherein a central angle in a plan view is provided in a region within 30 degrees starting from the center of the tap hole in the side wall portion. The bottom structure of a blast furnace as described in 1.

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