Weir, blast furnace runner, and molten iron removal method

Abstract

To provide a weir, a blast furnace runner, and a molten iron removal method that can suppress occurrence of vortex behind the weir and reduce mixing of molten iron into a slag flow S.SOLUTION: A weir 1 is installed upstream of an entrance to a slag runner 30 of a blast furnace runner 20, and has a downstream slope faced downward at a downstream side in a direction of a slag flow.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dam, a blast furnace runner, and a method for removing molten iron in the steelmaking field. [Background technology]

[0002] The pig iron produced in the blast furnace flows out of the tap hole of the blast furnace as a tapping flow, which contains a slag flow S and a molten iron flow P. Because the specific gravity of the slag flow S is smaller than that of the molten iron flow P, the molten iron flow P and the slag flow S that flow out of the tap hole are separated into two layers, with the molten iron flow P in the lower layer and the slag flow S in the upper layer.

[0003] A skimmer damper capable of blocking the molten iron flow P and the slag flow S is provided at a position in the blast furnace runner horizontally away from the blast furnace. Only the molten iron flow P, which has a high specific gravity, passes under the skimmer damper and flows out to the downstream side of the blast furnace runner, while the slag flow S, which has a low specific gravity, is blocked by the skimmer damper and flows into the slag runner upstream of the skimmer damper.

[0004] Here, the separation of the molten pig iron flow P and the slag flow S is not complete, and some of the molten pig iron flow P may be mixed into the slag flow S as molten pig iron. Since most of the slag flow S flowing out of the slag runner is water-cooled and granulated to become a cement raw material, if the molten pig iron is mixed into the slag flow S, there is a concern that the quality of the cement raw material may be reduced due to iron contamination. In addition, the mixing of the molten pig iron into the slag flow S reduces the durability of the slag runner. Furthermore, there is also the problem of a decrease in yield due to the molten pig iron that should have become a product raw material flowing out as the slag flow S. Therefore, the removal of the molten pig iron from the slag flow S is important in blast furnace operation.

[0005] In order to promote the separation of the two fluid layers of the slag flow S and the molten iron flow P in the blast furnace runner, for example, JP-A-10-273706, JP-A-4-044350, and JP-A-8-176628 disclose the provision of a weir upstream of the slag runner. The provision of the weir reduces the flow energy of the fluid flowing along the weir, slows down the flow velocity, and calms the undulations, promoting the separation of the slag flow S and the molten iron flow P. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-273706 [Patent Document 2] Publication number 4-044350 [Patent Document 3] Japanese Patent Application Publication No. 8-176628 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when a weir as disclosed in the above-mentioned prior art document is placed in the slag flow S, a large vortex may be generated behind the weir (downstream side), and the generated vortex may swirl up the molten iron flow P, increasing the amount of molten iron mixed into the slag flow S.

[0008] Therefore, a weir, a blast furnace runner, and a molten iron removal method that can suppress the generation of vortexes behind the weir and reduce the mixing of molten iron into the slag flow S are needed. [Means for solving the problem]

[0009] The weir of the present invention is a weir that is installed upstream of the entrance to a slag trough of a blast furnace trough and is characterized by having a downstream slope that faces downward downstream in the direction of the slag flow.

[0010] Furthermore, the blast furnace runner of the present invention is a blast furnace runner equipped with a weir installed upstream of the inlet of the slag runner, characterized in that the weir has a downstream slope facing downward downstream in the flow direction of the slag flow.

[0011] Furthermore, the molten iron removal method of the present invention is a method for removing molten iron from a slag flow of a tapping stream flowing through a blast furnace runner, and is characterized in that it includes flowing at least a part of the slag flow along a weir in a portion of the blast furnace runner upstream of the inlet of the slag runner, and the weir has a downstream slope facing downward downstream in the flow direction of the slag flow.

[0012] These configurations can reduce the generation of vortexes behind the weir and reduce the mixing of molten iron into the slag flow.

[0013] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited to the preferred embodiments described below.

[0014] The weir according to the present invention preferably has a downwardly convex curved surface connected to the lower end of the downstream slope.

[0015] According to this configuration, the generation of vortexes behind the weir can be further reduced, and the mixing of molten iron into the slag flow can be further reduced.

[0016] The weir according to the present invention preferably has an upstream slope facing downwards upstream in the direction of flow of the slug flow.

[0017] According to this configuration, the molten iron that comes into contact with the upstream slope is guided downward and moves toward the downward molten iron flow due to inertia, thereby further reducing the mixing of molten iron into the slag flow.

[0018] In the dam according to the present invention, it is preferable that the downstream slope has at least one of a concave portion and a convex portion.

[0019] According to this configuration, the generation of vortexes behind the weir can be further reduced, and the mixing of molten iron into the slag flow can be further reduced.

[0020] In the blast furnace runner according to the present invention, it is preferable that an upper surface of the weir is located at a height equal to or higher than the slag line.

[0021] According to this configuration, most of the slag flow can be guided along a path that follows the downstream slope of the weir, thereby further reducing the mixing of molten iron into the slag flow.

[0022] In the blast furnace runner according to the present invention, it is preferable that the lower end of the weir is located higher than the metal line.

[0023] According to this configuration, the phenomenon in which molten iron is lifted up from the molten iron flow into the slag flow by vortexes is unlikely to occur.

[0024] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings. [Brief description of the drawings]

[0025] [Figure 1] FIG. [Diagram 2] FIG. 2 is a cross-sectional view of a blast furnace trough (a cross-sectional view taken along line II-II in FIG. 1). [Diagram 3] FIG. 2 is a front view of the weir. [Figure 4] FIG. 1 is a top view of the weir. [Diagram 5] FIG. 2 is a side view of the weir. [Figure 6] FIG. 6 is a diagram showing a cross-sectional shape of the dam according to the first embodiment (an end view taken along line VI-VI in FIG. 3). [Figure 7] FIG. 11 is a diagram showing a cross-sectional shape of a dam according to a second embodiment. [Figure 8] FIG. 11 is a front view of a dam according to a second embodiment. [Figure 9] FIG. 11 is a diagram showing a cross-sectional shape of a dam according to a third embodiment. [Figure 10]FIG. 13 is a diagram showing a cross-sectional shape of a dam according to a fourth embodiment. [Figure 11] FIG. 11 is a diagram showing another embodiment of the dimple. [Figure 12] FIG. 13 shows another embodiment of a weir. [Figure 13] FIG. 4 is a diagram showing the installation position of a dam according to the embodiment. [Figure 14] FIG. 1 is a diagram showing the cause of vortex currents occurring in a dam according to the prior art. [Figure 15] FIG. 2 is a schematic diagram of a CFD simulation result of Example 1. [Figure 16] FIG. 1 is a schematic diagram of a CFD simulation result of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] [Configuration of blast furnace trough] The blast furnace runner 20 is a runner-shaped member provided to allow the flow of tapping iron flowing out from the tap hole Fo of the blast furnace BF. Fig. 1 shows a perspective view of the blast furnace runner 20, and Fig. 2 shows a vertical cross-sectional view of the blast furnace runner 20 along the direction in which the blast furnace runner 20 extends from the blast furnace BF side. Note that the flow direction, width direction, and downward direction of the blast furnace runner 20 are as shown in Fig. 1.

[0027] The pig iron produced in the blast furnace BF flows out of the tap hole Fo of the blast furnace BF as a tapping flow. At this time, the tapping flow contains a slag flow S and a molten pig iron flow P. Since the specific gravity of the slag flow S is smaller than that of the molten pig iron flow P, the molten pig iron flow P and the slag flow S that flow out of the tap hole Fo are separated into two layers, with the molten pig iron flow P in the lower layer and the slag flow S in the upper layer. Therefore, in the blast furnace runner 20, a two-layer flow of the molten pig iron flow P and the slag flow S is formed (Figure 2).

[0028] 1 and 2, the skimmer damper SD is provided so as to be able to dam the molten iron flow P and the slag flow S flowing through the blast furnace runner 20. Here, the lower end of the skimmer damper SD is provided at a position lower than the metal line ML, which is the interface between the molten iron flow P and the slag flow S, which are separated into two layers due to the difference in specific gravity. As a result, only the molten iron flow P passes below the skimmer damper SD.

[0029] On the other hand, the slag flow S blocked by the skimmer damper SD flows out into the slag runner 30 extending to the side of the direction in which the blast furnace runner 20 extends (the direction in which the tapping flow flows). To enable such outflow, the lower end of the inlet 31 of the slag runner 30 is located at a position lower than the slag line SL, which is the uppermost surface of the two-layer flow formed on the upstream side of the blast furnace runner 20.

[0030] Here, in order to promote separation of the two layers of the slag flow S and the molten iron flow P, a weir 1 is provided upstream of the inlet of the slag runner 30. In the blast furnace runner 20 according to this embodiment, a weir 1 having a unique shape is provided to suppress vortexes behind the weir 1 (downstream side), enhancing the layer separation effect. Four embodiments of possible shapes of the weir 1 are shown below. The weir 1 according to each embodiment is characterized mainly by the shape of the cross section along the flow direction of the tapping iron flow. In the following description, when the cross-sectional shape of the weir 1 is mentioned, it refers to the shape of the cross section along the flow direction of the tapping iron flow, unless otherwise specified.

[0031] [Weir structure] (Common matters) First, matters common to the weir 1 according to the four embodiments will be described. As shown in Fig. 3 to Fig. 6, the weir 1 is supported by two supports 2 and installed on the blast furnace runner 20. All of the weirs 1 according to the four embodiments have substantially the same cross-sectional shape at any position in the width direction of the blast furnace runner 20.

[0032] Since the weir 1 mainly comes into contact with the slag, the material of the weir 1 is a refractory material having high corrosion resistance to slag well known to those skilled in the art, such as a SiC-based refractory material.

[0033] The pillars 2 are plate-shaped and are provided at both ends of the weir 1. The two pillars 2 are provided along the side surfaces of both sides of the blast furnace runner 20, and the weir 1 is provided across the upper parts of these two pillars 2. That is, the weir 1 and the two pillars 2 form a gate-like structure, and the slag flow S and the molten iron flow P flow through this gate. The length LP of the plate-shaped pillar 2 along the flow direction is the same as the length L of the weir 1 along the flow direction. The height HP of the pillar 2 in the vertical direction is the height at which the weir 1 provided on the blast furnace runner 20 comes into contact with the slag flow S. The width WP of the pillar 2 in the direction facing the flow is set taking into consideration both the resistance to the flow and the strength to support the weir 1, and the width WP of one of the pillars may be, for example, about 1 / 9 of the width of the blast furnace runner 20. Furthermore, the shape of the horizontal cross section of the support 2 is not limited to a rectangle, and may be, for example, a streamlined cross section in consideration of the resistance of the tapping flow. The material of the support 2 is preferably the same as or similar to the material of the side surface of the blast furnace trough 20 to be installed.

[0034] Hereinafter, an embodiment of the present invention will be described based on a cross-sectional structure (end view taken along line VI-VI) of a central portion in the width direction of the blast furnace trough 20 of the weir 1.

[0035] (First embodiment) The weir 1a has an upper surface 11, a front surface 13, a curved surface 14, a downstream slope 15, and a rear surface 16 (Fig. 6). The upper surface 11 is a horizontal surface facing upward, and the front surface 13 is a vertical surface extending downward from the front end of the upper surface 11 and facing upstream in the flow direction. A curved surface 14 is provided that curves backward from the lower end of the front surface 13, and the curved surface 14 is continuously connected to the downstream slope 15. The rear end of the upper surface 11 and the rear end of the downstream slope 15 are connected by the rear surface 16, which is a curved surface that is convex downward in the flow direction. The front surface 13 and the curved surface 14 are connected at a connection part a, the curved surface 14 and the downstream slope 15 are connected at a connection part b, the downstream slope 15 and the rear surface 16 are connected at a connection part c, and the rear surface 16 and the upper surface 11 are connected at a connection part d.

[0036] The downstream slope 15 is a flat slope facing downward downstream of the flow direction. That is, the horizontal component of the normal to the downstream slope 15 faces the same direction as the flow direction, and the vertical component of the normal faces downward.

[0037] The curved surface 14 is a part of a cylindrical surface having a predetermined radius of curvature and is convex downward.

[0038] In the following description of other embodiments, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted or simplified. In addition, the description of the first embodiment applies to matters not specifically mentioned.

[0039] Second embodiment The weir 1b has a structure in which dimples 3, which are an example of recesses, are provided on the surfaces of the curved face 14, downstream slope 15 and rear face 16 of the weir 1a according to the first embodiment (FIGS. 7 and 8).

[0040] The dimples 3 are hemispherical recesses of radius r0 recessed from the surface of the weir 1b. Multiple rows of dimples 3 perpendicular to the flow direction are provided at approximately equal intervals on the curved surface 14, downstream slope 15 and rear surface 16 (10 rows in this embodiment). The dimples 3 are provided at equal intervals in each row, and the positions of the dimples 3 in two adjacent rows are offset from each other.

[0041] Third embodiment Weir 1c has an upper surface 11, a front surface 13, a downstream slope 15, a bottom surface 18, an upstream slope 17, and a rear surface 16 (FIG. 9). Instead of the curved surface 14 of weir 1a according to the first embodiment, weir 1c has an upstream slope 17 and a bottom surface 18. Also, whereas in the first embodiment, rear surface 16 is a curved surface that is convex downward in the flow direction, rear surface 16 in this embodiment is a vertical surface that faces downstream.

[0042] The upstream slope 17 is a flat slope facing downward on the upstream side of the flow direction. That is, the horizontal component of the normal to the upstream slope 17 faces the opposite direction to the flow direction, and the vertical component of the normal faces downward.

[0043] (Fourth embodiment) The weir 1d has an upper surface 11, a front surface 13, a curved surface 14, and a rear surface 16 (FIG. 10). The configuration of the rear surface 16 is the same as in the third embodiment. The cross-sectional shape of the weir 1d is axisymmetric with respect to the center line X. The front surface 13 and the curved surface 14 may be continuous or discontinuous at the connection part i. The same applies to the connection part l between the rear surface 16 and the curved surface 14.

[0044] (Other embodiments) In the above embodiment, the weir 1 is supported by two supports 2 and installed in the blast furnace runner 20. However, the weir 1 does not have to be supported by two supports 2. For example, the weir 1 may be arranged in the blast furnace runner 20 so as to span the width direction of the blast furnace runner 20 without using the supports 2, and the periphery of the part of the weir 1 that contacts the side of the blast furnace runner 20 may be fixed with a castable refractory such as a spraying material or mortar. The material of the castable refractory is preferably the same as or similar to the side of the blast furnace runner 20 to be installed. The weir 1 may also be supported by one, three, or any number of supports. Furthermore, the weir 1 may be installed in the blast furnace runner 20 in a suspended manner.

[0045] In the above embodiment, in the case where the upstream slope 17 is provided, a configuration (third embodiment) has been described in which a flat bottom surface 18 is provided between the downstream slope 15 and the upstream slope 17. However, a curved surface 14 may be provided between the downstream slope 15 and the upstream slope 17 ( FIG. 12 ), and the downstream slope 15 and the upstream slope 17 may be connected to each other.

[0046] In the above embodiment, a configuration has been described in which the weir 1 has the front surface 13, which is a vertical surface extending downward from the upper surface 11. However, if the weir 1 has the curved surface 14 or the upstream slope 17, it does not have to have the front surface 13. In this case, the upper end of the curved surface 14 or the upstream slope 17 is connected to the front end of the upper surface 11.

[0047] In the above embodiment, the weir 1 has been described as having the rear surface 16. However, the weir 1 does not have to have the rear surface 16. In this case, the rear end of the downstream slope 15 is connected to the rear end of the upper surface 11.

[0048] In the above embodiment, the weir 1 has been described in which the curved surface 14 has a constant radius of curvature r. However, the radius of curvature of the curved surface 14 may vary depending on the location. For example, the radius of curvature of the curved surface 14 may be gradually increased as it approaches the downstream slope 15, and the curved surface 14 may be smoothly connected to the downstream slope 15. Also, the curved surface 14 and the downstream slope 15 may be continuous curved surfaces. In other words, there may be no clear connection between the curved surface 14 and the downstream slope 15. The same applies to the case where the curved surface 14 and the upstream slope 17 are connected.

[0049] In the above second embodiment, the weir 1 is described in which the dimples 3, which are an example of recesses, are provided on the surfaces of the curved surface 14, the downstream slope 15, and the rear surface 16. However, when recesses are provided, the locations at which the recesses are provided are not limited. However, providing a recess on the downstream slope 15 is preferable because it is easier to obtain the effect of suppressing the generation of vortex currents.

[0050] In the above second embodiment, a configuration has been described in which the dimple 3 is a hemispherical recess that is recessed from the surface of the weir 1. However, the shape of the dimple 3 is not limited. For example, taking into consideration that the surface of the weir 1 is worn away, the dimple 3 may be configured to have a hemispherical portion 3a and a cylindrical portion 3b (FIG. 11). Furthermore, the dimple 3 may be in the shape of an ellipsoid, cone, polygonal pyramid, or teardrop recessed from the surface of the weir 1, a groove recessed along the flow direction, or the like.

[0051] In the above second embodiment, the weir 1 is described as being provided with dimples 3 as an example of recesses in order to obtain a straightening effect in a portion close to the surface of the weir 1. However, in order to obtain a straightening effect, protrusions may be provided. The protrusions may be provided on the curved surface 14, the bottom surface 18, or the surface of the downstream side slope 15. Specific examples of the shape of the protrusions include a hemisphere, an ellipsoid, a cone, a polygonal pyramid, a teardrop shape, and a rib protruding in the flow direction. Both recesses and protrusions may be provided.

[0052] In the above fourth embodiment, the weir 1 is described in which the front surface 13 and the curved surface 14 are directly connected, and the curved surface 14 and the rear surface 16 are directly connected. However, in the weir 1, the upstream slope 17 may be present between the front surface 13 and the curved surface 14, and the downstream slope 15 may be present between the curved surface 14 and the rear surface 16 (FIG. 12). In addition, in the first and third embodiments, the downstream slope 15 and the upstream slope 17 are described as flat surfaces, but as shown in FIG. 12, both the downstream slope 15 and the upstream slope 17 may be curved surfaces. The radii of curvature of these curved surfaces may be constant or may be partially different. The direction of the normal varies depending on the position on the downstream slope 15, but at any position, the horizontal component of the normal faces the same direction as the flow direction, and the vertical component of the normal faces downward. The direction of the normal line varies depending on the position on the upstream slope 17, but at any position, the horizontal component of the normal line faces the opposite direction to the flow direction, and the vertical component of the normal line faces downward. Furthermore, the downstream slope 15 and the curved surface 14 may have a common tangent at the connection part k, that is, the downstream slope 15 and the curved surface 14 may form a continuous curved surface. The same applies to the connection part j between the upstream slope 17 and the curved surface 14.

[0053] In the above embodiment, a configuration has been described in which the cross-sectional shape of the weir 1 is substantially the same at any position in the width direction of the blast furnace runner 20. However, the cross-sectional shape of the weir 1 does not have to be constant in the width direction of the blast furnace runner 20.

[0054] [Weir dimensions] The following describes preferred numerical ranges for the dimensions of the weir 1. The definitions of the dimensions such as height H mentioned below are as shown in Figs.

[0055] (Weir 1) The vertical height H of the weir 1 is defined as the difference in height from the upper end to the lower end of the weir 1 in the vertical direction when the weir 1 is installed in the blast furnace runner 20. The length L of the weir 1 in the flow direction is defined as the horizontal distance from the front end of the weir 1 facing the flow to the rear end facing the downstream side of the flow when the weir 1 is installed in the blast furnace runner 20.

[0056] The vertical height H of the weir 1 is preferably 30% or more of the depth of the slag flow S, and more preferably 40% or more. When the height H is 30% or more of the depth of the slag flow S, it is easy to reduce the flow energy of the fluid flowing along the weir, and it is easy to promote the separation of the two layers of fluid. The height H is preferably 90% or less of the depth of the slag flow S, more preferably 80% or less, and even more preferably 70% or less. When the height H is 90% or less of the depth of the slag flow S, it is easy to prevent the slag that has descended upstream of the weir 1 from being mixed into the molten iron, and it is also easy to prevent the molten iron from being entrained in the rising flow of slag downstream of the weir 1. Note that, as will be described later, when the upper surface of the weir 21 is installed at a position higher than the upper surface of the slag line SL, the height H is the height of the part of the weir 21 that is immersed in the slag flow S.

[0057] The length L of the weir 1 in the flow direction is preferably 300 mm or more, more preferably 400 mm or more, and even more preferably 500 mm or more. When the length L is 300 mm or more, it is easy to ensure the area of ​​the downstream slope 15 and to suppress the generation of vortex currents. The length L is preferably 1000 mm or less, more preferably 900 mm or less, and even more preferably 750 mm or less. When the length L is 1000 mm or less, it is possible to avoid an increase in the size of the weir 1, and the weir 1 is easy to manufacture and install.

[0058] (Downstream slope 15) The height H2 of the downstream slope 15 is defined as the difference in height between the lower end and the upper end of the downstream slope 15. The length L2 of the downstream slope 15 is defined as the horizontal distance between the lower end and the upper end of the downstream slope 15. When the curved surface 14 and the downstream slope 15 are directly connected, H2 and L2 are calculated by taking the lower end of the curved surface 14 as the lower end of the downstream slope 15. The angle α between the downstream slope 15 and the horizontal direction is defined as the angle between the horizontal direction and a virtual plane connecting the lower end and the upper end of the downstream slope 15. When the downstream slope 15 is a curved surface and the curved surface 14 and the downstream slope 15 are directly connected, the angle α is calculated by taking the lower end of the curved surface 14 as the lower end of the downstream slope 15.

[0059] The angle α between the downstream slope 15 and the horizontal direction is preferably 15 degrees or more, and more preferably 30 degrees or more. When the angle α is 15 degrees or more, the length L2 of the downstream slope 15 can be reduced, making it easier to reduce the dimensions of the weir 1. The angle α is preferably 75 degrees or less, and more preferably 60 degrees or less. When the angle is 75 degrees or less, it is easier to gently guide the flow and to reduce the generation of vortexes behind the weir 1.

[0060] The height H2 of the downstream side slope 15 is preferably 30% or more of H, more preferably 40% or more of H, and even more preferably 50% or more of H. When the height H2 is 30% or more of H, it is easy to ensure the area of ​​the downstream side slope 15 and to obtain the effect of suppressing vortex currents. The height H2 is preferably 80% or less of H, more preferably 70% or less of H, and even more preferably 60% or less of H. When the height H2 is 80% or less of H, it is easy to ensure a place to provide a structure such as the curved surface 14 or the rear surface 16.

[0061] (Curved surface 14) The radius of curvature r of the curved surface 14 is preferably 500 mm or less, more preferably 300 mm or less, and even more preferably 200 mm or less. When the radius of curvature r is 500 mm or less, the flow near the lower end B of the weir 1 is more likely to be gently guided by the curved surface 14, making it easier to obtain a vortex suppression effect. The radius of curvature r is preferably 50 mm or more, and more preferably 100 mm or more. When the radius of curvature r is 50 mm or more, the curve of the lower end B of the weir 1 becomes smooth and is less likely to wear down.

[0062] The radius of curvature r of the curved surface 14 is preferably 80% or less of H, more preferably 70% or less of H, and even more preferably 60% or less of H. When the radius of curvature r is 80% or less of H, the flow near the lower end B of the weir 1 is easily guided gently by the curved surface 14, and a vortex suppression effect is easily obtained. The radius of curvature r is preferably 30% or more of H, and more preferably 40% or more of H. When the radius of curvature r is 30% or more of H, the curve of the lower end B of the weir 1 becomes smooth and is less likely to wear out. When the curved surface 14 has a concave or convex portion, the radius of curvature r of the curved surface 14 is preferably 50 mm or more regardless of the ratio to H.

[0063] (Upstream slope 17) The height H3 of the upstream slope 17 is defined as the difference in height between the lower end and the upper end of the upstream slope 17. The length L3 of the upstream slope 17 is defined as the horizontal distance between the lower end and the upper end of the upstream slope 17. When the curved surface 14 and the upstream slope 17 are directly connected, H3 and L3 are calculated by taking the lower end of the curved surface 14 as the lower end of the upstream slope 17. The angle β between the upstream slope 17 and the horizontal direction is defined as the angle between the horizontal direction and a virtual plane connecting the lower end and the upper end of the upstream slope 17. When the upstream slope 17 is a curved surface and the curved surface 14 and the upstream slope 17 are directly connected, the angle β is calculated by taking the lower end of the curved surface 14 as the lower end of the upstream slope 17.

[0064] The angle β between the upstream slope 17 and the horizontal direction is preferably 15 degrees or more, more preferably 30 degrees or more, and even more preferably 45 degrees or more. When the angle β is 15 degrees or more, the length L3 of the upstream slope 17 can be reduced, making it easier to reduce the dimensions of the weir 1. The angle β is preferably 75 degrees or less, and more preferably 60 degrees or less. When the angle β is 75 degrees or less, the flow tends to flow gently downward along the upstream slope 17, making it easier to make the flow downstream of the weir 1 gentler.

[0065] The height H3 of the upstream slope 17 is preferably 10% or more of H, more preferably 20% or more of H, and even more preferably 30% or more of H. When the height H3 is 10% or more of H, it is easy to ensure the area of ​​the upstream slope 17, and it is easy to obtain the effect of guiding the molten iron downward. The height H3 is preferably 80% or less of H, more preferably 70% or less of H, and even more preferably 60% or less of H. When the height H3 is 80% or less of H, it is easy to ensure a place to provide a structure such as the front surface 13 or the curved surface 14.

[0066] (Dimple 3) The radius r0 of the dimple 3 is preferably 50 mm or less, and more preferably 35 mm or less. When the radius r0 is 50 mm or less, it is easy to avoid the occurrence of turbulent flow near the surface of the weir 1. The radius r0 is preferably 10 mm or more, and more preferably 25 mm or more. When r0 is 10 mm or more, it is easy to maintain the flow straightening effect even if the surface of the weir 1 is partially worn away by the slug flow S or clogged.

[0067] [Location of the dam in the blast furnace trough] The weir 1 is installed in the blast furnace runner 20 so that at least a portion of it is immersed in the slag flow S. The preferred range of the vertical height at which the weir 1 is immersed in the slag flow S is as described above with respect to the vertical height H of the weir 1.

[0068] In one embodiment, the upper surface 11 of the weir 1 is located at a height equal to or higher than the slag line SL. By installing the upper surface 11 of the weir 1 at a height equal to or higher than the slag line SL, most of the slag flow S can be guided along a path along the downstream slope 15 of the weir 1, thereby further reducing the mixing of molten iron into the slag flow S.

[0069] In one embodiment, the lower end B of the weir 1 (if the weir 1 has a bottom surface 18, the bottom surface 18 is the lower end B of the weir 1; the same applies below) is located higher than the metal line ML. When the lower end B of the weir 1 is located higher than the metal line ML and away from the molten iron flow P, it is easy to suppress the swirling of the molten iron caused by the vortex on the back side of the weir 1.

[0070] In one embodiment, the lower end B of the weir 1 is located lower than the lower end of the entrance 31 of the slag trough 30. As shown by the arrow q in Fig. 13, part of the slag flow S flowing between the lower end B of the weir 1 and the metal line ML flows downstream of the weir 1 without coming into contact with the weir 1, but if the lower end B of the weir 1 is located lower than the lower end of the entrance 31 of the slag trough 30, the molten iron, which has a higher specific gravity than the slag, is less likely to float from the position of the lower end B of the weir 1 to the entrance 31 of the slag trough 30, making it easier to prevent the molten iron from mixing with the slag flowing into the slag trough 30.

[0071] [Hot metal removal method] In the molten iron removal method of this embodiment, in the portion upstream of the entrance 31 of the slag trough 30 of the blast furnace trough 20, at least a portion of the slag flow S is caused to flow along a weir 1 having a downstream slope 15 facing downward downstream in the flow direction.

[0072] By making at least a part of the slag flow S flow along the weir 1 before the slag flow S flows into the inlet 31 of the slag trough 30, the flow energy of the flowing fluid is reduced, promoting separation of the two fluid layers and making it easier to remove the molten iron contained in the slag flow S. In addition, by providing the weir 1 with the downstream slope 15, it is possible to prevent the vortex on the back side of the weir 1 from lifting up the molten iron from the molten iron flow P into the slag flow S, making it easier to remove the molten iron contained in the slag flow S.

[0073] As shown in Figure 14, the weir disclosed in the prior art document has a rectangular cross section. When a slug flow S flows along a weir with a rectangular cross section, the area of ​​the flow path suddenly widens as the slug flow S passes through the downstream corner of the lower end of the weir. At this time, the slug flow S moves straight ahead due to inertia (arrow n), making it difficult for a flow toward the back side of the weir (arrow m) to occur. As a result, a space is created behind the weir to which the slug flow S is difficult to be supplied, and the pressure in this space becomes lower than the surrounding area. It is believed that this pressure difference causes the slug flow S to flow into this space from the surrounding area, resulting in a vortex.

[0074] In contrast, in the weir 1 according to this embodiment, by providing the downstream slope 15, the increase in the flow path area downstream of the lower end B of the weir 1 is gentler, making it easier for the slag flow S to flow along the weir 1. This makes it difficult for pressure changes to occur behind the weir 1, making it difficult for vortexes to occur, and making it easier to suppress the lifting up of molten iron.

[0075] When the weir 1 according to this embodiment has an upstream slope 17, the slag flow S is guided obliquely downward by the upstream slope 17. The molten iron contained in the slag flow S has a higher specific gravity than the slag, and therefore has a greater inertia during movement than the slag. Therefore, when the slag flow S is guided downward along the upstream slope 17, the inertia of the molten iron moving downward is greater than the inertia of the slag moving downward. In other words, a difference occurs in the downward propulsive force between the molten iron and the slag, and due to this difference, only the molten iron merges with the molten iron flow P. This makes it easier to separate the molten iron contained in the slag flow S.

[0076] When the weir 1 according to this embodiment has a curved surface 14, the descent and ascent of the slag flow S at the lower end B of the weir 1 is gently guided by the curved surface 14, making it more difficult for vortexes to occur on the back side and easier to remove the molten iron from the slag flow S. The downstream portion of the curved surface 14, like the downstream slope 15, has the effect of suppressing the occurrence of vortexes on the back side of the weir 1, and the upstream portion of the curved surface 14, like the upstream slope 17, has the effect of guiding the molten iron in the slag flow S downward.

[0077] Furthermore, in the weir 1 according to this embodiment, by providing at least one of a concave portion and a convex portion on the downstream slope 15, small turbulence can be generated near the surface of the downstream slope 15. This makes it even more difficult for vortexes to be generated behind the weir 1, making it even easier to remove molten iron from the slag flow S.

[0078] In the weir 1 according to this embodiment, when the rear face 16 is made inclined instead of vertical as in the first and second embodiments, the effect of guiding the slag flow S gently upward can also be obtained at the rear face 16. By replacing a part of the downstream side of the downstream slope 15 with a rear face 16 that slopes upward at an angle greater than α, the length L of the weir 1 can be reduced. EXAMPLES

[0079] The present invention will be further described below with reference to examples, but the present invention is not limited to the following examples.

[0080] 1.Conditions for CFD simulation A CFD simulation was performed on the flow of the slag flow S near the weir when the weir was placed in the slag flow S of the blast furnace runner 20. However, in this simulation, in order to reduce the calculation load, a molten iron model was not set, and a slag model was used instead of the molten iron model. In other words, in this simulation, a model was placed in which an object with the same fluid properties as the slag flows in the part corresponding to the molten iron flow P.

[0081] The CFD calculation conditions were as follows:

[0082] As a model of slag, density is 2800kg / m 3 The fluid was set to have a viscosity of 0.224 Pa s and a flow velocity of 0.04 m / s. The surface layer was set to air (20°C, 1 atm), the turbulent flow model was K-ε, and the free surface model was the VOF method. The number of meshes was approximately 110,000 for Examples 1, 3 to 5 and Comparative Examples 1 and 2, and approximately 140,000 for Example 2 having dimples 3.

[0083] A model of the blast furnace runner 20 near the part where the weir 1 is installed was set up with a length of 10,904 mm (corresponding to the part between 7,699 mm and 18,603 mm from the tap hole Fo), a width of 900 mm, and a depth of 1,000 mm. The thickness of the air layer on the surface of the slag was set to 300 mm. The front end of the weir 1 facing the upstream side was installed 16,000 mm from the tap hole Fo. The overall width of the weir 1 was set to 900 mm, and the width WP of the support 2 was set to 100 mm. Therefore, the width of the part below the weir 1 through which the slag flow S passes was set to 700 mm.

[0084] Simulations were performed under the above conditions for each of the examples and comparative examples, and the results were output as a flow velocity distribution diagram in a vertical section (a section along the flow direction) at the center of the width direction of the blast furnace trough 20. For the flow velocity distribution diagram, the vertical section flow velocity was displayed as a vector, and the flow velocity and flow direction were compared. Schematic diagrams of the simulation results are shown in Figures 15 and 16.

[0085] Based on the observation results of the flow velocity distribution diagram, the magnitude of the vortex flow behind the weir was evaluated on a five-level scale of AA, A to D for each of the examples and comparative examples. AA: Under calculation conditions with a mesh count of approximately 140,000, almost no vortex currents are observed behind the weir. A: Under calculation conditions with a mesh count of approximately 110,000, almost no vortexes are observed behind the weir. B: Whirlpools can be seen behind the weir, but their extent does not extend beyond the bottom of the weir. C A small vortex was observed behind the weir, and the area in which the vortex occurred extended beyond the bottom of the weir. D A large vortex is occurring behind the weir.

[0086] Of these, ratings AA, A and B were deemed effective in preventing the intrusion of molten iron, while ratings C and D were deemed ineffective in preventing the intrusion of molten iron.

[0087] In the following examples and comparative examples, the reference numerals of the respective faces constituting the end face of the weir are the same as those in the above-mentioned embodiments, and each example corresponds to one of the above-mentioned four embodiments.

[0088] 2. Model shapes and evaluation results for each example Example 1 A weir model was created according to the first embodiment (FIGS. 6 and 15). In this example, the height H of the weir 1 was 300 mm, and the length L was 600 mm. The height H1 of the front surface 13 was 150 mm, the radius of curvature r of the curved surface 14 was 150 mm, and the location of θ=30 degrees downstream from the lower end B of the curved surface 14 was the connection part b. The angle α of the downstream side slope 15 was 30 degrees, and the height H2 was 180 mm. In addition, the radius of curvature R of the rear surface 16 connecting the connection part c and the connection part d was 300 mm.

[0089] Example 1 was rated an A.

[0090] Example 2 A weir model was created according to the second embodiment (FIGS. 7 and 8). In Example 2, a weir model was created in which dimples 3 were provided on the weir 1 of Example 1. The radius r0 of the dimples 3 was set to 25 mm. Ten rows of dimples 3 were provided on the curved surface 14, downstream slope 15, and rear surface 16. Of these, the horizontal distance L0 of the row of dimples 3 on the downstream slope 15 was set to 75 mm. Within each row, the minimum distance H0 between adjacent dimples 3 was set to 50 mm. The offset H00 between two adjacent rows of dimples 3 was set to 50 mm.

[0091] Example 2 was rated AA.

[0092] Example 3 A weir model according to the first embodiment was set up (FIGS. 6 and 15). The length L of the weir 1 was 600 mm, the same as in Example 1, but the height H was 550 mm, higher than in Example 1. The height H1 of the front surface 13 was 400 mm, the radius of curvature r of the curved surface 14 was 150 mm, and the location at θ=60 degrees downstream from the lower end B of the curved surface 14 was the connection part b. The angle α of the downstream side slope 15 was 60 degrees, and the height H2 was 380 mm. The radius of curvature R of the rear surface 16 connecting the connection part c and the connection part d was 300 mm.

[0093] Example 3 was rated a B.

[0094] Example 4 A weir model according to the third embodiment was set up (Fig. 9). The height H of the weir 1 was set to 550 mm, and the length L was set to 400 mm. The angle α of the downstream slope 15 was set to 34 degrees, the height H2 was set to 100 mm, and the length L2 was set to 150 mm. The angle β of the upstream slope 17 was set to 40 degrees, the height H3 was set to 150 mm, and the length L3 was set to 300 mm.

[0095] Example 4 was rated a B.

[0096] Example 5 A weir model according to the third embodiment was created (Fig. 9). The height H of the weir 1 was 550 mm, and the length L was 600 mm. The angle α of the downstream slope 15 was 40 degrees, the height H2 was 250 mm, and the length L2 was 300 mm. The angle β of the upstream slope 17 was 34 degrees, the height H3 was 100 mm, and the length L3 was 150 mm.

[0097] Example 5 was rated a B.

[0098] Example 6 A weir model according to the fourth embodiment was created (Fig. 10). The height H of the weir 1 was set to 550 mm, and the length L was set to 600 mm. The radius of curvature r of the curved surface 14 was set to 305 mm, and the distance H4 from the center o of the curved surface 14 to the upper surface 11 was set to 245 mm.

[0099] Example 6 was rated a B.

[0100] Comparative Example 1 A model of a weir with a rectangular cross section was created (Fig. 16). The weir had a top surface, a front surface, a bottom surface, and a rear surface. The distance from the top surface to the bottom surface, i.e., the height H of the weir in the vertical direction, was set to 550 mm, and the distance from the front surface to the rear surface, i.e., the length L of the weir in the flow direction, was set to 600 mm.

[0101] Comparative Example 1 was rated D.

[0102] Comparative Example 2 A model of a weir with a rectangular cross section was created (FIG. 16). The settings were the same as those in Comparative Example 1, except that the height H of the weir in the vertical direction was set to 300 mm.

[0103] Comparative Example 2 was rated C. [Industrial Applicability]

[0104] The present invention can be used, for example, in a blast furnace runner for circulating molten iron flowing out of a blast furnace. [Explanation of symbols]

[0105] 20 Blast furnace trough 30 Slag trough 31 Slag gutter entrance BF blast furnace Fo tap hole P hot metal flow Slug flow SD Skimmer Damper ML Metal Line SL Slug Line 1 Weir 2 pillars 3 Dimples 14 Curved Surfaces 15 Downstream slope 17 Upstream slope 13 Front 16 Rear 11 Top side 18 Bottom

Claims

1. A weir installed upstream of the entrance of a slag trough of a blast furnace trough, A downstream slope facing downward in the direction of flow of the slug flow; Weir.

2. A curved surface that is convex downward and connected to the lower end of the downstream side slope is provided. The dam of claim 1.

3. The slug flow has a downwardly facing upstream slope in the direction of flow of the slug flow. The dam of claim 1.

4. The dam according to any one of claims 1 to 3, wherein the downstream slope has at least one of a concave portion and a convex portion.

5. A blast furnace runner having a weir installed upstream of the inlet of the slag runner, The weir has a downstream slope facing downward downstream in the direction of flow of the slug flow. Blast furnace trough.

6. The blast furnace trough according to claim 5 , wherein an upper surface of the weir is located at a height equal to or higher than the slag line.

7. The blast furnace runner according to claim 5 or 6, wherein a lower end of the weir is located higher than a metal line.

8. 1. A method for removing molten iron from a slag stream of a tapping stream flowing through a blast furnace runner, comprising the steps of: In a portion upstream of the inlet of the slag runner of the blast furnace runner, directing at least a portion of the slug stream along a weir; The weir has a downstream slope facing downward downstream in the direction of flow of the slug flow. Hot metal removal method.

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