JP2015101734A - Converter blowing top-blow lance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converter blowing top-blow lance capable of improving secondary combustion ratio.SOLUTION: A converter blowing top-blow lance 1 generates interference between adjacent two jets, and suppresses reduction of a side surface area of a jet by preventing condensation of all jets to one, and includes a nozzle part 1a by having plural nozzles A, A'. In the converter blowing top-blow lance 1, in the respective nozzles A, A', in a right hand system xyz orthogonal coordinate system in which outlets 3 of the nozzles A, A' are positioned on a positive side on an x-axis, a central axis of the converter blowing top-blow lance 1 is a z-axis, a positive direction of the z-axis is an upstream side of top-blow gas jetted from the outlets of the nozzles A, A', when an angle formed by a projection line of the central axis of the nozzles A, A' to an xy plane and the x-axis is α, the nozzle A having the α angle and the nozzle A' having -α angle are alternately disposed so that the respective kinds of nozzles are disposed more than two.

Description

  The present invention relates to an upper blowing lance used when a refining gas and powder are sprayed onto a hot metal bath surface in a steelmaking converter.

  There is a smelting reduction iron making method as an iron making method without using a blast furnace. As one type of the smelting reduction iron manufacturing method, there is a method using an upper bottom blowing type converter vessel. In this method, the hot metal produced is partly left as hot water for the next charge, iron ore and a heat source such as coal are charged into it, and oxygen is blown into the hot metal from the top blowing lance. There is a method of granting.

  Although it is possible to use a lance used in a normal converter as the top blowing lance, the main purpose of the top blowing is not decarburization reaction of hot metal, but C and H supplied from a heat source such as coal. It is required to have characteristics that can promote the secondary combustion, by causing the secondary combustion to actively generate secondary combustion and applying heat.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 5-239525), Patent Document 2 (Japanese Patent Laid-Open No. 11-21610), and the like have proposed nozzles that can improve secondary combustion / heat application efficiency. These lances are different in nozzle shape from the lances used in ordinary converters. The lance nozzle proposed in Patent Document 1 is non-circular, and the nozzle proposed in Patent Document 2 has a special structure for imparting a swirling flow to the jet. For this reason, the lances proposed in these patent documents are very expensive as compared with the lances used in ordinary converters.

  In addition, in order to stabilize the operation at the time of high-speed blowing using secondary combustion, studies have been made to suppress the attenuation of the jet sprayed from the nozzle. For example, Patent Document 3 (Japanese Patent Laid-Open No. 2006-328432) proposes a lance in which a sub nozzle is arranged around a main nozzle. According to Patent Document 3, since the jet ejected from the sub nozzle forms a high temperature zone by secondary combustion, the density of the ambient gas around the jet ejected from the main nozzle is reduced, and the jet ejected from the main nozzle This reduces the amount of atmospheric gas entrained in the jet, suppresses jet attenuation, and increases the dynamic pressure of the jet.

JP-A-5-239525 Japanese Patent Laid-Open No. 11-21610 JP 2006-328432 A

  However, in the lance disclosed in Patent Document 3, a secondary combustion zone is formed immediately below the sub nozzle, so that the efficiency of heat application to the bath is low, and the refractory melt damage may deteriorate. Providing the sub nozzle increases the side area of the jet, which may be effective in increasing secondary combustion, but the jet ejected from the sub nozzle is very likely to cause secondary combustion. This is the cause of the problems such as the reduction of ignition efficiency and the deterioration of refractory melting as described above. Further, in the invention described in Patent Document 3, secondary combustion is increased only directly under the nozzle in order to reduce the entrainment of atmospheric gas into the jet ejected from the main nozzle. It is considered that the increase in the secondary combustion rate cannot be expected.

  An object of the present invention is to provide an upper blowing lance for converter blowing that can suppress a significant increase in manufacturing cost when compared with an ordinary blowing upper lance for converter and can promote secondary combustion. .

  In the present invention, the secondary combustion efficiency was examined without increasing the secondary combustion promoting sub nozzle like the lance disclosed in Patent Document 3. As a result, it was found that the interference between jets was caused by jets ejected from two nozzles.

  By doing so, secondary combustion just below the nozzle is suppressed like the sub nozzle, while the jet interferes downstream from the nozzle just below (near the slag) and activates secondary combustion. it can. In conventional porous lances, when jets from all nozzles interfere with each other, the jets condense into one, so the side area of the jet is reduced and the secondary combustion rate is increased due to the effect. It will be suppressed.

  Therefore, in order to complete the present invention, a shape that increases the secondary combustion rate by suppressing the reduction of the side area by preventing all the jets from condensing together while causing two adjacent jets to interfere with each other. investigated.

  As a result, the knowledge that the total number of nozzles is at least 4 or more is obtained because the gas flow in the furnace is not symmetrical in the case of 2 holes and the refractory melting rate may be increased. .

  In order to increase the symmetry of the jet ejected from the lance, it is desirable that the nozzles be arranged on the same circumference with the central axis of the lance as the center.

  Also, from the viewpoint of securing the cross-sectional area of the cooling water channel of the lance, and in order to avoid an increase in the difficulty of manufacturing the lance, the total number of nozzles on the same circumference is 16 holes or less, and the nozzles to the xy plane When the angle formed by the projected straight line of the central axis and the x axis is the twist angle α (deg), the twist angle α is preferably 60 ° or less.

  Further, similarly from the above viewpoints, in each nozzle, when the angle between the central axis of the nozzle and a straight line parallel to the z-axis passing through the center of the outlet of the nozzle is an inclination angle β (deg), the inclination is The angle β is preferably 30 ° or less.

  As for the nozzle diameter and the inclination angle β, it is desirable that the two types of nozzles be the same because the lance is easily manufactured, and there is no need to provide a difference.

  A center hole may be provided in the top blowing lance in order to prevent adhesion of the metal to the center of the lance. When the throat cross-sectional area of the center hole is increased, the jets are united together by causing interference with the surrounding holes. For this reason, it is desirable that the ratio of the throat cross-sectional area of the central hole to the total throat cross-sectional area of all nozzles is 5.0% or less.

The present invention has been devised from the above idea.
That is, according to the present invention, (1) in an upper blowing lance for converter blowing comprising a nozzle portion having a plurality of nozzles, the central axis of the upper blowing lance for converter blowing is the z axis in each nozzle. A right-hand system determined such that the positive direction of the z-axis is on the upstream side of the upper blowing gas ejected from the outlet of the nozzle, and the outlet of the nozzle is positioned on the positive side of the x-axis In the xyz Cartesian coordinate system, when the angle formed by the projection axis of the central axis of the nozzle on the xy plane and the x axis is defined as α, two types of nozzles having an angle of α and a nozzle having an angle of −α No. 2 nozzles are alternately disposed, and the top blowing lance for converter blowing is characterized by the above.

In the present invention, α does not include 0 °.
As a preferred embodiment of the present invention, (2) the upper blowing lance for converter blowing according to the above (1), wherein α is more than 0 ° and not more than 60 °.

  (3) In each nozzle, when the angle formed by a straight line passing through the center of the nozzle outlet and the z-axis and the central axis of the nozzle is an inclination angle β (deg), the inclination angle β is 30 ° or less. The top blowing lance for converter blowing according to (1) or (2) above, wherein

  (4) The upper blowing lance for converter blowing according to (3) above, wherein the inclination angles β of the nozzles are the same.

  (5) The upper blow lance for converter blowing, which is any one of (1) to (4) above, wherein the nozzles have the same nozzle shape.

  (6) Each said nozzle is arrange | positioned on the same circumference centering on the center axis | shaft of the said upper blowing lance for converter blowing continuous, Any of said (1) to said (5) characterized by the above-mentioned. It is an upper blowing lance for converter blowing.

  (7) The converter blowing upper lance has a center hole, and the center hole is arranged in the nozzle portion so that the center axis overlaps the center axis of the converter blowing upper lance. A top blow lance for converter blowing, which is any one of (1) to (6) above.

  (8) The blast cross-sectional area of the central hole is 5.0% or less with respect to the total throat cross-sectional area of all nozzles, and the top blow for converter blowing according to (7) above Lance.

  By using the top blowing lance for converter blowing according to the present invention, while causing interference between two adjacent jets, all the jets are not condensed into one, thereby reducing the side area of the jets. Suppressing the secondary combustion rate can be dramatically increased.

FIG. 1 is a schematic cross-sectional view of a tip portion of an upper blowing lance for converter blowing according to the present invention. FIG. 1 (a) is a plan view of the upper blowing lance for converter blowing according to the present invention. 1B is a cross-sectional view taken along the line bb ′ of FIG. 1A, FIG. 1C is a cross-sectional view taken along the line cc ′ of FIG. 1A, and FIG. It is d 'sectional drawing.

  The top blowing lance for converter blowing according to the present invention is used when a jet, which is mainly an oxygen-containing gas, is sprayed on the hot metal charged in the converter and blown. Hereinafter, the top blowing lance of this invention is explained in full detail using FIG.

  FIG. 1 is a schematic cross-sectional view of a tip portion of an upper blowing lance 1 of the present invention, FIG. 1 (a) is a plan view of the upper blowing lance 1 of the present invention, and FIG. 1 (b) is a plan view of FIG. FIG. 1C is a sectional view taken along line bb ′ of FIG. 1A, and FIG. 1D is a sectional view taken along line dd ′ of FIG. In FIG. 1B, FIG. 1C, and FIG. 1D, one nozzle A is shown for easy explanation of the upper blow lance 1 of the six holes.

  As shown in FIG. 1A, the upper blowing lance 1 includes a nozzle portion 1a having a plurality of nozzles A and A ′. Specifically, the nozzle portion 1a includes two sets of nozzles A and A ′. Have. Moreover, as shown in FIG.1 (b), FIG.1 (c), and FIG.1 (d), the upper blowing lance 1 has the lance inner pipe | tube 1b other than the nozzle part 1a. The lance inner pipe 1b has a flow path of an oxygen-containing gas or the like sprayed on the hot metal accommodated in the converter type refining vessel. The flow path has a tubular shape with a substantially uniform inner diameter up to the nozzle portion 1a, and is generally shaped so that the cross-sectional area of the flow path does not change rapidly with respect to the gas and powder traveling directions. Have been made. The nozzle A of the nozzle portion 1a extends so as to communicate with the flow path of the nozzle inner tube 1b. The oxygen-containing gas that has passed through the flow path enters from the inlet 2 of the nozzle A and is ejected from the outlet 3 toward the molten steel.

  As shown in FIGS. 1A to 1D, the upper blowing lance 1 is configured such that, in the nozzle A, the central axis of the upper blowing lance 1 is the z axis, and the positive direction of the z axis is the nozzle A. In the right-handed xyz Cartesian coordinate system determined so that it is located upstream of the upper blowing gas ejected from the outlet 3 and the outlet 3 of the nozzle A is positioned on the positive side on the x axis, When the angle between the projection line of the central axis of the nozzle A and the x axis is defined as α, the two types of nozzles, the nozzle A having the angle α and the nozzle A ′ having the angle −α, are alternately 2 More than one are arranged.

  As shown in FIGS. 1A and 1D, the upper blowing lance 1 includes three nozzles A having α (hereinafter, referred to as “twist angle α” as appropriate) and an inclination angle β, and a twist angle. Three nozzles A ′ having −α and an inclination angle β are alternately arranged on the same circumference. The nozzle A having a twist angle of α and the nozzle A ′ having a twist angle of −α are disposed adjacent to each other. Since the central axes of the nozzle A and the nozzle A ′ intersect, the jets ejected from the nozzles also interfere with each other and the oscillation increases. At the same time, the upper blowing lance 1 has three sets of such nozzles A and A ′. Therefore, since the jets interfere with each other and the reduction of the side area of the jet is minimized, the secondary combustion rate is dramatically improved.

  The twist angle α is larger than 0 ° in order to cause the jets ejected from the nozzles to interfere with each other. In addition, it is desirable that the position where the jets interfere with each other is in the vicinity of the slag, which is downstream of the nozzles, from the viewpoint of activating secondary combustion. For this reason, the twist angle α is desirably 10 ° or more. Moreover, in order to ensure the cross-sectional area of the cooling water channel currently piped by the outer cylinder of a lance, and to avoid that the difficulty of lance manufacture increases, it is desirable that the twist angle (alpha) is 60 degrees or less.

  Each nozzle preferably has an inclination angle β of 30 ° or less, where an angle formed by a straight line parallel to the z-axis passing through the center of the nozzle outlet and the central axis of the nozzle is an inclination angle β (deg). . By providing this angle, it is possible to secure the cross-sectional area of the cooling water channel of the lance and avoid an increase in the difficulty of manufacturing the lance. It is desirable that the inclination angle β of each nozzle is the same in order to reduce the difficulty of manufacturing the lance.

  The total number of nozzles of the top blowing lance 1 needs to be 4 or more. When the top blow lance 1 of the present invention is used, interference is caused between two adjacent jets, and all jets are not condensed into one, thereby suppressing a reduction in side area and increasing a secondary combustion rate. Can do. Further, the total number of nozzles on the same circumference increases the refractory erosion rate by eliminating the symmetry of the gas flow in the furnace in the case of two holes. It is necessary to have more than pairs. Therefore, the top blowing lance 1 needs to have two or more nozzles for making the jets interfere with each other, that is, the total number of nozzles is four or more. Moreover, in order to ensure the cross-sectional area of the cooling water channel currently piped by the outer cylinder of a lance, and to avoid that the difficulty of lance manufacture increases, it is desirable that the total number of nozzles is 16 holes or less.

  The shape of the nozzles A and A ′ may be a cylindrical shape (straight nozzle) or a so-called Laval shape (Laval nozzle). In the case of a cylindrical shape, the area of the cross section is the area of the cross section at any position from the inlet 2 to the outlet 3 in FIGS. 1 (b) to 1 (d). In the case of the Laval type that is commonly used in the top blowing lance, the cross-sectional area of the nozzle throat is defined as the area of the cross section of the nozzle A. The nozzle shape of each nozzle is preferably the same in order to reduce the difficulty of lance production. Each nozzle is preferably arranged on the same circumference around the central axis of the upper blowing lance 1 in order to improve the productivity by improving the symmetry of the jet ejected from the lance.

  As shown in FIG. 1A, the top blowing lance 1 of the present invention may be provided with a center hole 4 in order to prevent the adhesion of the metal to the center of the lance. The center hole 4 extends in communication with the flow path of the lance inner pipe 1b, like the nozzles A and A '. The center hole 4 may have a cylindrical shape or a Laval shape like the nozzle A in order to avoid an increase in the difficulty of manufacturing the lance. The cross-sectional area is the same as nozzles A and A '. Further, the center hole 4 is disposed in the nozzle portion 1 a so that the center axis overlaps the center axis of the upper blowing lance 1. If the cross-sectional area of the central hole is large, it causes interference with the surrounding holes and causes the jets to merge together. For this reason, the cross-sectional area of the center hole 4 is desirably 5.0% or less with respect to the total cross-sectional area of all the nozzles A.

  A 2.5t test converter was charged with 2.0t of hot metal at 1400 ° C as seed water, 10kg of lump lime as auxiliary materials, and 6kg of lump meteorite, and while blowing oxygen from the top blowing lance against this hot metal, Lump coke and lump iron ore were added each time from the top of the furnace in the first half of blowing so that the hot metal temperature remained in the range of 1400 ° C to 1450 ° C.

The components of the hot metal used as the seed bath are [C] = 4.3 mass%, [Si] <0.01 mass%, [Mn] = 0.03 mass%, and [P] = 0.03 mass%. In addition, Ar gas was blown from the bottom blowing tuyere at 0.5 Nm ³ / min for stirring the molten iron. The upper blowing lance was separately blown for the case where a normal lance was used (comparative example) and the case where the lance according to the present invention was used (example). Table 1 shows the shape of the lance used in the comparative examples and the examples, and the distance between the tip of the lance and the bath surface (lance height) during blowing.

The oxygen flow rate is 4.0 Nm ³ / min, and the lance height is set so that the ratio L / L ₀ of the bath dent depth L to the bath depth L ₀ by the jet as an index of the top blowing stirring strength is 0.16. Each height was adjusted with a lance. In addition, the dent depth L was calculated | required by (1) Formula.

vd = 0.73 (L + h) L ^1/2 (1)
Here, v: vertical component (m / s) of the apparent jet velocity at the nozzle tip, d: nozzle diameter (mm), L: depth of recess (mm), and h: lance height (mm).

  In each of the comparative examples and examples, the blowing was performed for 15 minutes, and after the blowing, it was confirmed that the added lump ore and lump coke did not remain unreacted, and the oxygen gas supplied during blowing The average secondary combustion rate during blowing was calculated by mass balance with the amount, hot metal before and after blowing, and slag composition. Table 1 shows the average secondary combustion rate.

  In Comparative Examples 1 to 6, the torsion angle α was 0 °, so the secondary combustion rate was in the 30% range, whereas in the examples using the top blowing lance according to the present invention, the torsion angle α Was 10 to 60 °, the secondary combustion rate could be increased to the 40% range. Moreover, the difference was not looked at by the melting rate of the refractory by the comparative example and the Example.

DESCRIPTION OF SYMBOLS 1 Top blowing lance 2 Nozzle inlet 3 Nozzle outlet 4 Center hole 5 Nozzle center axis 6 A straight line parallel to the z-axis passing through the center of the nozzle outlet

Claims (1)

In an upper blowing lance for converter blowing comprising a nozzle portion having a plurality of nozzles,
In each of the nozzles, the central axis of the converter blowing upper blow lance is the z axis, and the positive direction of the z axis is upstream of the upper blown gas ejected from the outlet of the nozzle. In the right-handed xyz orthogonal coordinate system determined so that the outlet of the nozzle is positioned on the positive side on the x-axis,
When the angle formed by the projection axis of the central axis of the nozzle on the xy plane and the x axis is defined as α,
An upper blowing lance for converter blowing, wherein two or more nozzles having an angle of α and a nozzle having an angle of −α are alternately arranged in two or more.

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