JP3758718B2 - Porous lance tuyere for steel making - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a steelmaking porous lance tuyere used for converter blowing or the like, and more particularly to an improvement in the structure of a cooling water channel for cooling a heat receiving surface of a steelmaking porous lance tuyere.
[0002]
[Prior art]
Converter smelter lance tuyere is used to eject high pressure oxygen toward molten steel at a close distance of 1.5 to 4.0 meters from the hot molten steel surface. For this reason, the tuyere receives intense radiant heat from the molten steel, and further receives a significant heat load because metal is also attached. Therefore, in general, the lance tuyere has a triple tube structure of an outer tube, an intermediate tube, and an inner tube. High-pressure oxygen flows through the inner tube, and cooling water flows between the inner tube and the inner tube. It flows toward the tip, the flow moves between the middle pipe and the outer pipe at the tip of the lance, cools the inside of the heat receiving surface facing the molten steel at the tip of the lance, and rises between the middle pipe and the outer pipe. The cooling water comes back. Here, when the oxygen hole is porous, there is a problem that in the cooling of the heat receiving surface, there is a wall of the oxygen hole in the cooling water channel between the middle pipe and the outer pipe, so that the stagnation of the flow occurs and the cooling cannot be sufficiently performed. It was. Many improvements have been proposed. For example, (1) the gap between the inner surface of the tip and the middle tube is narrowed so that the linear velocity of the cooling water on the heat receiving surface is 18 m / sec or more (Japanese Patent Laid-Open No. 3-229814)
(2) Forming a flow in one direction without stagnation (Japanese Patent Laid-Open No. 48-103405)
(3) A cooling water outlet is provided asymmetrically and a spiral is generated at the center of the tuyere (Japanese Patent Laid-Open No. 1-312023)
(4) A plurality of cooling water inlets installed along the front end of the oxygen hole (Japanese Patent Laid-Open No. 61-15911)
(5) Cooling water swirls in opposite directions to prevent flow interference (Japanese Patent Laid-Open No. 53-90109)
and so on.
[0003]
[Problems to be solved by the invention]
However, in the inventions of JP-A-3-229814 and JP-A-48-103405, the stagnation region on the back of the oxygen hole is not lost, so that sufficient cooling cannot be performed. The inventions disclosed in Japanese Patent Application Laid-Open No. 61-15911 and Japanese Patent Application Laid-Open No. 53-90109 have a problem that the structure is complicated and the manufacturing cost increases. Therefore, when the oxygen hole is porous, in cooling the heat receiving surface, the stagnation of the flow due to the presence of the wall of the oxygen hole in the cooling water channel between the middle tube and the outer tube is eliminated, and a cooling water channel that is sufficiently cooled is provided. It was difficult to realize at low cost.
[0004]
Therefore, the present invention eliminates the stagnation of the flow due to the presence of the wall of the oxygen hole in the cooling water channel between the middle pipe and the outer pipe when cooling the heat receiving surface when the oxygen hole is porous, and sufficiently cools the heat receiving surface. A porous lance tuyere for steel making that can realize a cooling water channel at low cost is provided.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a cooling water channel between the outer tube and the middle tube of the lance behind the curved surface (heat receiving surface) where the porous oxygen hole at the tip of the tuyere opens. In the cooling water channel outside the conical surface passing through the central axis of the oxygen hole and inside the circumscribed conical surface common to all oxygen holes, along the streamline, in the vertical direction of the lance It is characterized in that straight ribs are installed in the curved or lance vertical direction . Moreover, it is preferable that the number of divisions of the cooling water channel is 3 to 5.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a steel-made porous lance tuyere having five oxygen holes will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a steel-made porous lance tuyere with five oxygen holes and a transverse sectional view of a flow path of cooling water 9 between an intermediate tube 4 and an outer tube 6 along a heat receiving surface 8. . The lance tuyere has a triple tube structure of an outer tube 6, an intermediate tube 4, and an inner tube 2, and the inner tube 2 is an oxygen passage 1 through which high-pressure oxygen flows. The supply cooling water 3 flows between the inner tube 2 and the middle tube 4 toward the heat receiving surface 8 at the tip of the tuyere, and the flow 9 moves between the middle tube 4 and the outer tube 6 at the tip of the tuyere, and the tip of the lance. The inner side of the heat receiving surface 8 facing the molten steel is cooled, and the cooling water 9 is returned between the intermediate tube 4 and the outer tube 6. FIG. 2 is a proof diagram showing both the conventional tuyere 11 and the tuyere 12 of the present invention. In FIG. 2, in the conventional lance tuyere without the rib 16, when the oxygen hole 7 is porous, the wall of the oxygen hole 7 is provided in the cooling water channel between the middle tube 4 and the outer tube 6 in cooling the heat receiving surface 8. Therefore, the stagnation of the flow 10 occurred and the cooling could not be performed sufficiently.
[0007]
In order to eliminate the problem of flow stagnation 10, as shown in the region 12, a curved surface (heat receiving surface 8) in which the oxygen hole 7 at the tip of the tuyere opens between the outer tube 6 and the middle tube 4 of the lance. In the cooling water channel behind the inside of the cooling water channel outside the conical surface 14 passing through the central axis of all the oxygen holes and inside the circumscribed conical surface 15 common to all the oxygen holes 7, along the streamline, to divide the cooling water channel is installed a linear rib in the vertical direction of the curved or lance in a vertical direction of the lance.
[0008]
Here, the division number of the flow path is preferably 3 to 5 in consideration of an increase in pressure loss and production efficiency.
As a specific form, for example, in the method of dividing the flow path into three equal parts, the distance AB and A′B ′ between the rib start point B and the oxygen hole 7 and the distance BB ′ between the rib start points satisfy the equation (1), The end points C and C ′ of the ribs are placed on a part FCC′F ′ of the circumscribed conical surface 15 of each oxygen hole so as to be plane-symmetric with respect to the plane that bisects the two oxygen holes 7. In order to satisfy the equation (2), the plane is symmetrical with respect to a plane that bisects the two oxygen holes 7. Note that the point F is an intersection of the oxygen hole 7 and the conical surface 15 on the cross section of FIG.
[0009]
AB = BB ′ = B′A ′ (1)
FC = CC '= C'F' (2)
The starting point B and the ending point C of the rib are between the two conical surfaces 14 and 15 and satisfy the expression (3). The points D and G are the center point and end point of the cooling water channel narrowed most by the walls of the two oxygen holes 7, and the point E is the intersection of the straight line passing through the point D and the center of the lance and the conical surface 15. is there.
[0010]
0.1 × DE ≦ BC ≦ DE (3)
The effect of the lance tuyere will be described with reference to FIGS. As described above, FIG. 2 also compares the flow velocity distributions of the conventional tuyere 11 and the tuyere 13 of the present invention. In the cross section DG between the oxygen hole 7 and the oxygen hole 7, the cross-sectional area is small, so the flow rate is large and there is no problem of stagnation. On the other hand, since the cross-sectional area rapidly increases at the downstream cross-section EF ″, not only does the flow velocity decrease rapidly at the conventional tuyere, but also the flow velocity decreases greatly at the F ″ side. On the other hand, in the present invention, since the flow velocity distribution is equalized by the ribs, the uneven flow velocity distribution is eliminated as in E′F ′ of the tuyere 13 of the present invention in FIG. Also, the rib is located between the outer tube and the middle tube of the lance, outside the conical surface passing through the central axis of all oxygen holes in the cooling water channel behind the curved surface (heat receiving surface) where the oxygen holes at the tip of the tuyere open. In the cooling water channel inside the circumscribed conical surface common to all oxygen holes, it is installed in the vertical direction of the lance so as to divide the cooling water channel along the streamline. The itch of the flow is also eliminated.
[0011]
3 compares the flow velocity distributions in the EF ″ and E′F ′ cross sections of FIG. 2 when the conventional method and the present invention are applied. In the conventional method, the flow velocity is high between ECs and slow between CFs. However, the flow is distributed by the ribs, and an almost uniform flow is realized.
As described above, when the lance tuyere oxygen hole is porous, in the cooling of the heat receiving surface, the stagnation of the flow due to the presence of the wall of the oxygen hole in the cooling water channel between the middle pipe and the outer pipe can be eliminated and the cooling can be sufficiently performed. A cooling water channel can be provided at low cost.
[0012]
【Example】
Hereinafter, an embodiment in which the water channel of the present invention is simply divided will be described in detail with reference to FIGS. The diameter of the lance tuyere used was 0.6 m and there were 5 oxygen holes. The diameter of each oxygen hole is 0.2 m, and the diameter of the concentric circle 14 is 0.3 m. The cooling water flows at 20 m / s in the center of FIG. In this case, in the conventional method, a portion (flow stagnation 10 in FIG. 2) where the flow rate is 5 m or less per second is generated outside the oxygen hole 7. Here, the shape when the water channel is divided into three by ribs in FIG. 2 is determined by the equations (4) to (7).
[0013]
AB = B′A ′ = 0.035 [m] (4)
BB '= 0.03 [m] (5)
FC = CC ′ = C′F ′ = 0.17 [m] (6)
BC = 0.2 × DE = 0.02 [m] (7)
When this lance tuyere is used, in the cooling of the heat receiving surface, there is no stagnation of the flow rate at which the flow velocity is 5 m / s or less due to the existence of the oxygen hole wall in the cooling water channel between the middle pipe and the outer pipe. I was able to cool it. In addition, because it can be cooled sufficiently, damage due to radiant heat from molten steel and a significant heat load due to adhesion of metal is reduced, and the replacement period of tuyere is changed from the conventional 100 times to 250 times as shown in FIG. Prolonged life.
[0014]
With reference to the same drawings, an embodiment of the water channel of the present invention divided equally will be described in detail. Here, the number of divisions was similarly set to three, and the shape of the ribs in FIG. 2 was determined by equations (8) to (10).
AB = BB ′ = B′A ′ = 0.03 [m] (8)
FC = CC ′ = C′F ′ = 0.17 [m] (9)
BC = 0.3 × DE = 0.03 [m] (10)
When this lance tuyere was used, in the cooling of the heat receiving surface, there was no stagnation of the flow rate caused by the presence of oxygen holes between the middle tube and the outer tube, and the flow rate became 5 m / s or less, and the heat receiving surface was sufficiently cooled. In addition, because it can be cooled sufficiently, damage due to radiant heat from molten steel and a significant heat load due to adhesion of metal is reduced, and the replacement period of tuyere is changed from the conventional 100 times to 250 times as shown in FIG. I knew it would prolong life.
[0015]
【The invention's effect】
When the porous lance tuyere for steel making of the present invention is used, when the oxygen hole is porous, in the cooling of the heat receiving surface, the stagnation of the flow due to the presence of the wall of the oxygen hole in the cooling water channel between the middle pipe and the outer pipe Thus, it is possible to provide a cooling water channel that sufficiently cools at low cost.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a (a) longitudinal sectional view and (b) a transverse sectional view of a porous lance tuyere for steel making having five oxygen holes according to the present invention.
FIG. 2 is an explanatory diagram of a difference in flow velocity distribution between a tuyere according to the present invention and a conventional tuyere.
FIG. 3 is a diagram showing the position of the flow velocity distribution according to the present invention in comparison with the conventional method.
FIG. 4 is a diagram showing the effect of the present invention in comparison with a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Oxygen channel 2 ... Inner pipe | tube 3 ... Supply cooling water 4 ... Middle pipe | tube 5 ... Return cooling water 6 ... Outer pipe | tube 7 ... Oxygen hole 8 ... Heat receiving surface 9 ... Cooling water flow direction 10 ... Flow stagnation 11 ... Conventional tuyere (Part) and flow velocity distribution 12 ... the tuyere of the present invention (part)
13 ... Flow velocity distribution 14 in the tuyere of the present invention ... Conical surface 15 passing through the central axis of all oxygen holes 7 ... circumscribed conical surface 16 common to all oxygen holes 7 ... ribs

Claims (2)

Inside the cooling water channel between the outer and middle tubes of the lance behind the curved surface (heat receiving surface) where the porous oxygen hole at the tip of the tuyere opens, outside the conical surface passing through the central axis of all oxygen holes And ribs that are curved in the vertical direction of the lance or linear in the vertical direction of the lance so as to divide the cooling water channel along the streamline in the cooling water channel inside the circumscribed conical surface common to all oxygen holes Perforated lance tuyere for steel making, characterized in that it is installed. The perforated lance tuyere for steel making according to claim 1, wherein the number of divisions of the cooling water passage is 3 to 5.

Images