JP5277979B2 - Top blowing lance for molten metal refining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a top-blowing lance for the refinement of a molten metal, which can not only reduce a variation of a dynamic pressure in a circumferential direction but also optimize a distribution of the dynamic pressure in a radial direction, and thereby further can reduce a spitting quantity. <P>SOLUTION: The top-blowing lance 1 for the refinement of the molten metal has 3 or more holes of nozzles 2 arranged on the same circumference at equal spaces. In an XYZ rectangular coordinate system which is determined so that a lance center axis is regarded as a Z-axis and an outlets of the nozzles are positioned on an X-axis, when angles formed by respective projected lines of the nozzle axis onto a YZ plane and an XZ plane and Z axis are defined as &alpha; and &beta; respectively, the angles satisfy 0&lt;tan&alpha;/tan&beta;&lt;2.75, and a ratio of the cross sectional area of the center hole 3 arranged in the central part of the nozzles with respect to the total cross sectional area of the nozzles, &gamma;=(d<SB>1</SB><SP>2</SP>/(d<SB>1</SB><SP>2</SP>+n&times;d<SB>2</SB><SP>2</SP>))&times;100, satisfies 3.2 to 10, wherein d<SB>1</SB>represents a diameter (mm) of the center hole; d<SB>2</SB>represents diameters (mm) of other holes; and n represents the number of other arranged holes. In the case of a lance with multiple holes having different diameters, in which the diameters of other holes are not equal, (d<SB>1</SB><SP>2</SP>+n&times;d<SB>2</SB><SP>2</SP>) is replaced with (d<SB>1</SB><SP>2</SP>+4S/&pi;), where the total cross sectional area of the nozzles except the center hole is represented by S. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an upper blowing lance for molten metal refining used for blowing a refining gas to molten metal in a steelmaking converter, for example.

  In recent years, due to the widespread use of hot metal pretreatment facilities such as de-Si and de-P, the main role of the converter is decarburization only. For this reason, in the steelmaking factory which has these facilities, the less slag blowing which hardly adds an auxiliary raw material is performed. In order to improve productivity in the steelmaking process, it is a problem how to shorten the converter decarburization treatment for all molten steel. That is, it is important to shorten the blowing time by increasing the acid feed rate.

  However, when the hot metal is decarburized at high speed in the converter, spitting and dust due to the top blown oxygen jet increase, resulting in a decrease in iron yield and an operation hindrance due to adhesion of metal to the furnace mouth. In order to reduce this spitting, it is effective to make the lance porous, which can disperse the energy when the oxygen gas jet collides with the bath surface. In the current steelmaking converter, a porous lance is used. Is common. Perforated lances are nozzles with three or more holes on the same circumference and are inclined at regular intervals and usually so that the extension of each nozzle axis intersects at one point on the center axis of the lance. is there.

  In the porous lance, the larger the number of nozzles, the greater the effect of dispersing the collision energy of the oxygen gas jet, which is advantageous for reducing spitting. However, the increase in the number of nozzles in the porous lance is naturally limited. That is, if the number of nozzles becomes too large, cavities corresponding to the nozzles (the dents in the bath surface due to the collision of the oxygen gas jet) are overlapped, which may promote spitting.

  In order to solve this problem, Patent Document 1 discloses an invention in which spit is reduced by arranging a plurality of sub-injection holes on the inner surface of the outlet part of the main injection hole and smoothing the flow velocity distribution of the jet. Has been.

  However, in order to implement the invention disclosed in Patent Document 1, it is necessary to increase the number of oxygen flow paths in the lance, and the tip shape of the lance becomes complicated, which increases the manufacturing cost of the lance. There is a problem.

  Therefore, the applicant of the present invention, according to Patent Document 2, relates to a molten metal refining top blow lance (hereinafter referred to as “twist lance”) that can smooth the flow velocity distribution of the jet without complicating the shape of the tip of the lance. The invention was proposed. FIG. 1A is a schematic diagram showing the tip of a normal porous lance, and FIG. 1B is a schematic diagram showing the tip of a torsion lance. In FIG. 1 (a) and FIG. 1 (b), reference numeral 1 is a lance and reference numeral 2 is a nozzle.

  In the normal porous lance 1, as shown in FIG. 1A, each nozzle 2 is inclined so that the extension of the central axis thereof intersects at one point on the central axis of the lance 1. As shown in FIG. 1B, the torsion lance 1 is arranged so that each nozzle 2 is inclined so that the extensions of the central axes thereof are twisted with respect to each other.

  In this Patent Document 2, in a six-hole twisted lance, the distribution of the dynamic pressure of the jet in the radial direction from the center axis of the lance is investigated, and the direction in which the dynamic pressure is maximum when viewed from the center of the lance Twist so that the peak dynamic pressure value in each direction is close to the direction corresponding to the boundary with the nozzle (the direction where the dynamic pressure is the smallest), that is, the dynamic pressure fluctuation in the circumferential direction is small A range of degrees δ was proposed. And it was disclosed that the amount of spitting can be reduced by this torsion lance.

JP-A-8-269530 Japanese Patent No. 3396522 JP-A-60-165313

  According to the torsion lance proposed by Patent Document 2, the dynamic pressure fluctuation in the circumferential direction is reduced, so that the amount of spitting is reduced. Here, the dynamic pressure distribution of the jet in the radial direction also affects the spitting amount. However, this torsion lance does not consider the suppression of the dynamic pressure fluctuation of the jet in the radial direction. That is, in the torsion lance proposed in Patent Document 2, if the radial dynamic pressure distribution can be optimized, the amount of spitting can be further reduced.

  The object of the present invention is to not only reduce the dynamic pressure fluctuation in the circumferential direction in the torsion lance proposed by Patent Document 2, but also to optimize the dynamic pressure distribution in the radial direction. An object is to provide an upper blowing lance for molten metal refining that can further reduce the amount of spitting.

  In Patent Document 2, a small-diameter hole that hardly interferes with jets from other nozzles may be arranged at the center of the lance. That is, in Patent Document 2, it is recommended that the jet from the central hole should not interfere with the jet from the other hole.

  However, as described above, the dynamic pressure distribution in the radial direction also affects spitting. In order to change the dynamic pressure distribution in the radial direction, it is effective to make the jet from the central hole positively interfere with the jet from the other hole. The present invention is based on such novel findings that are not disclosed in Patent Document 2.

  According to the present invention, in a top lance for metal refining having nozzles having three or more holes arranged at equal intervals on the same circumference, the center axis of the lance is set to the Z axis, and the outlet position of the nozzle is set to the X axis. In the XYZ orthogonal coordinate system, when the angles formed by the projection of the nozzle axis on the YZ plane and the XZ plane with respect to the Z axis are α and β, respectively, α and β satisfy the following expression (1), and the nozzle center The upper blow lance for molten metal refining is characterized in that the ratio γ of the cross-sectional area of the central hole installed in the section to the total cross-sectional area of the nozzle satisfies the following formulas (2) and (3).

tan10 ° ≦ tanα / tanβ ≦ tan60 ° (1)
3.2 ≦ γ ≦ 10 (2)
γ = (d ₁ ² / (d ₁ ² + n × d ₂ ² )) × 100 (3)
In the formula (3), d ₁ is the diameter (mm) of the center hole, d ₂ is the diameter (mm) of the other hole, n is the number of other holes, and the different-diameter porous where the diameter of the other hole is not constant. In the case of a lance, S is the total cross-sectional area of the nozzle excluding the center hole, and (d ₁ ² + n × d ₂ ² ) in equation (3) is replaced with (d12 + 4S / π).

  By using the upper blow lance for molten metal refining according to the present invention in a refining process of blowing a refining gas on the molten metal bath surface, not only can the dynamic pressure fluctuation in the circumferential direction be reduced, but also in the radial direction. As a result, the amount of spitting loss can be greatly reduced.

  Thereby, while improving the refined iron yield, generation | occurrence | production of operation troubles, such as adhesion of a furnace neck metal, can be avoided and productivity can be improved.

FIG. 1A is a schematic diagram showing a tip portion of a normal porous lance, and FIG. 1B is a schematic diagram showing a tip portion of a torsion lance disclosed in Patent Document 2. As shown in FIG. FIG. 2 is a schematic diagram showing an example of a tip portion of an upper blow lance for molten metal refining according to the present invention, where FIG. 2 (a) is a plan view, and FIG. 2 (b) is a B- in FIG. FIG. 7C is a projection view of the B section on the yz plane, and FIG. 10C is a projection view of the CC section of FIG. FIG. 3 is a schematic diagram showing a geometrical positional relationship between one nozzle and a corresponding hot spot when the top blow lance for molten metal refining according to the present invention is used in a molten metal refining furnace. FIG. 4 is a schematic view showing a water model experimental apparatus with a scale of 1/10. FIG. 5 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of the 6-hole lance where the twist δ is 0 ° and the cross-sectional area ratio γ of the center hole is 0%. FIG. 6 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance central axis of the 6-hole lance having a twist degree δ of 0 ° and a cross-sectional area ratio γ of 4%. FIG. 7 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of the 6-hole lance having a twist degree δ of 30 ° and a cross-sectional area ratio γ of 0%. FIG. 8 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of the 6-hole lance having a twist degree δ of 30 ° and a cross-sectional area ratio γ of 5.5%. FIG. 9 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of the 6-hole lance having a twist degree δ of 70 ° and a cross-sectional area ratio γ of 0%. FIG. 10 is a graph showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of a 6-hole lance with a twist degree δ of 70 ° and a cross-sectional area ratio γ of the center hole of 5.5%.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.
FIG. 2 is a schematic diagram showing an example of the tip of the upper blow lance 1 for molten metal refining according to the present invention, where FIG. 2 (a) is a plan view, and FIG. 2 (b) is B in FIG. 2 (a). FIG. 4C is a projection view of the −B cross section onto the yz plane, and FIG. 4C is a projection view of the CC cross section of FIG. That is, in FIG. 2, description will be made using an XYZ orthogonal coordinate system in which the lance center axis is the Z axis and the outlet position of the nozzle 2 is on the X axis.

  The lance 1 corresponds to an angle α (hereinafter referred to as “nozzle turning angle”) formed by the projection of the nozzle axis on the YZ plane, which corresponds to the twist of the nozzle, and the inclination in the outer direction of the nozzle. Six nozzles 2 having a projection of the nozzle axis on the XZ plane and an angle β formed by the Z axis (hereinafter referred to as “nozzle inclination angle”) are arranged on the axis object at equal intervals around the lance axis. . Similarly to the torsion lance disclosed in Patent Document 2, in order to reduce spitting by reducing the dynamic pressure fluctuation in the circumferential direction, the angles α and β are expressed by the following equation (1): 0 <tan α / The relationship of tan β <2.75 is satisfied.

  Note that in a normal porous lance where the nozzle axis intersects at one point on the Z axis (for example, disclosed in Patent Document 3), the angle α is 0 °, and the angle β is the angle of the nozzle in the normal lance. It corresponds to.

In the lance 1, the ratio γ of the cross-sectional area of the central hole 3 installed in the center of the nozzle to the total cross-sectional area of the nozzle is represented by the following expression (2): 3.2 ≦ γ ≦ 10, and (3): γ = (D ₁ ² / (d ₁ ² + n × d ₂ ² )) × 100 is satisfied. However, in (3), _{d 1} is the center hole 3 diameter (mm), _{d 2} is the nozzle 2 is another pore diameter (mm), n is the number of installed other hole, other holes In the case of a different diameter porous lance with a non-constant diameter, the total cross-sectional area of the nozzle 2 excluding the center hole 3 is S, and (d ₁ ² + n × d ₂ ² ) in the equation (3) is (d ₁ ² + 4S). / Π).

Hereinafter, the reason will be described.
FIG. 3 is a schematic diagram showing the geometrical positional relationship between one nozzle 2 and the corresponding fire point 5 when the torsion lance 1 is used in a molten metal refining furnace.

As shown in the figure, the angle formed by the projection of the perpendicular line drawn from the center of the fire point 5 (the position where the extension of the nozzle axis intersects the molten metal bath surface 4) to the Z axis on the XY plane and the X axis is a twist degree. When defined as δ, (δ, α, β, torsion lance 1−bath surface distance H ₀ , and the distance D between the outlet position of the nozzle 2 and the center axis of the lance (see FIG. 2B) ( 4) The relationship of the formula is established.

tan δ = H ₀ tan α / (H ₀ tan β + D) (4)
In this equation (4), if the distance D is sufficiently smaller than the distance H ₀ , δ can be obtained approximately by equation (5).

δ = tan ⁻¹ (tan α / tan β) (5)
The distance R between the center of the hot spot 5 on the bath surface and the lance center axis position is given by the equation (6).

R = H ₀ (tan ² α + tan ² β) ^1/2 (6)
Next, in the same-diameter porous lance in which the diameters of the nozzles 2 are the same, the ratio γ of the cross-sectional area of the central hole 3 and the cross-sectional area of all the holes 2 is defined by equation (7).

γ = (d ₁ ² / (d ₁ ² + n × d ₂ ² )) × 100 (7)
In equation (7), d ₁ indicates the diameter of the center hole 3, d ₂ indicates the diameter of the nozzle 2 that is another hole, and n indicates the number of other holes installed. In the case of a different-diameter porous lance, the total cross-sectional area of the nozzle 2 excluding the center hole 3 is S, and (d ₁ ² + n × d ₂ ² ) in the equation (7) is (d ₁ ² + 4S / π) Replace with

And about this twist lance 1, the influence which the twist degree (delta) of the nozzle 2 and the cross-sectional area ratio (gamma) of a center hole have on the droplet scattering speed was investigated by water model experiment.
FIG. 4 is a schematic view showing a water model experimental apparatus with a scale of 1/10. In FIG. 4, reference numeral 6 indicates scattered droplets, and reference numeral 7 indicates water supply paper for measurement.

  As the torsion lance 1 shown in FIG. 4, 6-hole lances 1 to 19 having the specifications shown in Table 1 were prepared, and a water model experiment was performed for each.

  In Table 1, the lance No. Reference numerals 1 and 2 are lances corresponding to the conventional type in which the central axis of each nozzle 2 intersects at one point on the Z-axis, and only the cross-sectional area ratio γ of the central hole 3 is changed to 0% and 4%. is there. In Table 1, the lance No. Reference numerals 3 to 19 denote lances in which the directions of the nozzles 2 excluding the center hole 3 are twisted with respect to each other. As in 1 and 2, it is constant at 98 mm, and the twist degree δ in the formula (2) is 10 to 70 ° and the cross-sectional area ratio γ of the center hole is 0 to 7.5%.

  In this water model experiment, in FIG. 4, the distance between the lance 1 and the water surface 4 was set to 270 mm, and compressed air was blown upward from the lance 1 at a flow rate of 1000 Nl / min. Meanwhile, the water absorbent paper 7 was placed at a position 800 mm above the water surface 4, and the scattering speed Sp of the droplet 6 was calculated from the weight change before and after that. This droplet 6 assumes spitting in a converter.

  However, the measured droplet scattering speed Sp is the lance No. The value at 3 was indexed as 1 and compared. The evaluation of those having an Sp value of 0.8 or less was evaluated as ◯, and the evaluation of those having an Sp value exceeding 0.8 was evaluated as ×. Under the same conditions, the flow velocity distribution of the jet on the plane corresponding to the water surface was measured by the dynamic pressure distribution by the Pitot tube. The spitting measurement results are also shown in Table 1.

For a lance having a twist degree δ of 10 ° to 60 ° and a cross-sectional area ratio γ of the center hole 3 of 3.2% to 10%, the Sp value was 0.80 or less.
On the other hand, when the twist degree δ was 0 ° and 70 °, the Sp value greatly exceeded 1 even if the cross-sectional area ratio γ was 4%.

  5 to 10 are graphs showing the dynamic pressure distribution of the jet in the radial direction from the lance center axis of the 6-hole lance, and FIG. 5 shows the cross-sectional area ratio γ of the center hole when the twist δ is 0 °. 6 shows a case where the twist degree δ is 0 ° and the cross-sectional area ratio γ is 4%, and FIG. 7 shows a cross-sectional area where the twist degree δ is 30 °. 8 shows a case where the ratio γ is 0%, FIG. 8 shows a case where the twist degree δ is 30 ° and the cross-sectional area ratio γ is 5.5%, and FIG. 9 shows a case where the twist degree δ is 70 °. In both cases, the case where the cross-sectional area ratio γ is 0% is shown, and FIG. 10 shows the case where the twist degree δ is 70 ° and the cross-sectional area ratio γ of the center hole is 5.5%. The graphs of FIGS. 5 to 10 show only the measurement results in the radial direction with respect to the azimuth where the dynamic pressure takes the maximum value and the azimuth where the minimum value as seen from the center of the lance.

  First, as shown in the graphs of FIGS. 5 and 6, in the conventional lance 1 having a twist degree δ of 0 °, the jet from the central hole 3 and the jet from the other nozzle 2 are obtained even if the cross-sectional area ratio γ is 4%. However, the maximum dynamic pressure value of the jet from the other hole remained high.

  On the other hand, as shown by graphs in FIGS. 7 and 8, in the lance 1 having a twist degree δ of 30 °, the cross-sectional area ratio γ is set to 5.5% so that the jet from the central hole 3 and the other nozzle 2 It can be seen that there is a region where the dynamic pressure is almost constant due to interference with the jets from.

  Further, as shown in graphs in FIGS. 9 and 10, in the lance 1 having a twist degree δ of 70 °, the jet from the center hole 3 and the jet from the other nozzle 2 excessively interfere with each other and are close to the lance center axis. The maximum value of dynamic pressure was found at the position.

  As described with reference to the graphs of FIGS. 5 to 10, according to this water model experiment, when the twist δ is 30 ° and the cross-sectional area ratio γ is 5.5%, the dynamic pressure distribution is in the circumferential direction. In addition to the smoothness in the radial direction, the droplet scattering speed Sp decreases as a result. And, from the effect of reducing the droplet scattering speed Sp shown in Table 1, in the lance where the twist δ is 10 ° or more and 60 ° or less and the cross-sectional area ratio γ is 3.2% or more and 10% or less, The dynamic pressure distribution becomes smooth not only in the circumferential direction but also in the radial direction, and as a result, the droplet scattering speed Sp decreases.

Furthermore, when the twist degree δ is 70 °, the coalescence due to the mutual interference between the jets proceeds rapidly, and as a result, the droplet scattering speed is increased.
Next, the case where the lance according to the present invention is blown at a converter with an inner diameter of 7 m at 270 tons / charge and an acid feed rate of 60000 Nm ³ / hour is taken as an example, the nozzle inclination angle, the lance height and the center hole A method for determining the cross-sectional area ratio γ will be described.

As shown in the examples described later, the spitting amount increases when the twist degree δ of the nozzle obtained by the equation (6) is 70 ° or more. This is because the interference coalescence between jets is strengthened and the effect of smoothing the dynamic pressure distribution is diminished. Therefore, the twist degree δ is determined to be less than 70 °. That is, the relationship between α, β, and δ is 0 ° <tan ⁻¹ (tan α / tan β) <70 °, that is, 0 <tan α / tan β <2.75.

Next, the distance H ₀ between the lance 1 and the liquid level will be described. If the distance H0 is too small, the lance will be easily melted and thermally deformed due to molten steel scattering, and the lance life will be shortened. On the other hand, if the distance H ₀ is too large spread of the jet is increased, similarly to when too large a nozzle inclination angle, the problem of the two-o'clock combustion and refractory wear CO gas is produced. For the above reasons, in an actual converter, the distance H ₀ is desirably 2200 mm or more and 3500 mm or less.

  In the upper blow lance 1 for molten metal refining according to the present invention, the number of nozzles 2 excluding the center hole 3 is 3 or more. This is because if the number of nozzles 2 is 2 or less, the symmetry of the reaction in the converter is lost. The upper limit of the number of nozzles 2 is not particularly defined, but if the number of nozzles 2 is excessive, the structure of the tip of the lance 1 becomes complicated, and the momentum of the jet per nozzle 2 becomes too small. For reasons such as this, it is desirable to set it to 10 or less.

  In addition, although it is suitable to use the top blowing lance 1 for molten metal refining which concerns on this invention for the steelmaking process by a top bottom blowing converter, it is not limited to this and uses only a top blowing lance. It can be applied to steelmaking processes and other metal refining processes that supply refining gas from top blowing lances such as AOD furnaces and copper refining furnaces.

  In this way, by using the upper blow lance for molten metal refining according to the present invention in a refining process in which a refining gas is sprayed on the molten metal bath surface, only the dynamic pressure fluctuation in the circumferential direction can be reduced. In addition, since the dynamic pressure distribution in the radial direction can be optimized, the amount of spitting loss can be greatly reduced.

The present invention will be described more specifically with reference to examples.
In an upper bottom blowing converter with a molten steel amount of 270 tons / charge, low carbon steel was melted using the top blow lance for molten metal refining according to the present invention, and the amount of spitting loss (Sp loss) was investigated.

Blowing is all slag blowing using P-removal (slag amount is 30 to 35 kg per ton of molten steel), top flow oxygen flow rate is 55000 Nm ³ / hr, bottom blowing gas is CO ₂ 2000 Nm ^{3 /} hr, lance The height was fixed at about 2.7 m. The end point [C] was constant at about 0.05%.

  As the lance, a conventional lance without twist or a lance in which the directions of the nozzles are twisted with respect to each other and provided with a center hole, the twist degree δ is 10 to 70 °, and the sectional area ratio γ of the center hole is 0. -11%.

  Table 2 shows the number of nozzles, nozzle diameter, angle α, angle β, torsion δ and cross-sectional area ratio γ of Examples 1 to 9 and Comparative Examples 1 to 11, and the amount of spitting loss during operation. Show. These values are average values when 10 to 20 charges are used for each lance.

  With respect to the amount of spitting loss, the amount of increase / decrease relative to Comparative Example 3 was indicated by weight%. And it was considered effective when the Sp loss was reduced by 0.2% or more.

  First, Comparative Examples 1 and 2 will be described. When the twist δ was 0 °, the spitting loss amount was as high as +1.25 to 1.28% even when the cross-sectional area ratio γ was 5.5%. In a state where there is no twist, it was not possible to reduce the amount of spitting loss by properly interfering the jet from the central hole and the jet from other nozzles.

  Next, Comparative Examples 3 to 8 will be described. Even when the twisting degree δ was applied at 10 to 60 °, the spitting loss amount could be reduced only by 0.08% or less when the cross-sectional area ratio γ was as small as 0 to 2.5%. Since the cross-sectional area ratio γ is small, the interference between the jet from the central hole and the jet from the other nozzles is weak, and a smooth dynamic pressure distribution in the radial direction cannot be obtained.

  Next, Comparative Examples 9 to 11 will be described. Even when the twisting degree δ is given in the range of 10 to 60 °, if the cross-sectional area ratio γ is excessively 11%, the amount of spitting loss has rather increased. When the cross-sectional area ratio γ is excessively large, the jet from the center hole interferes with the jets from other nozzles, and the maximum dynamic pressure position moves near the center axis. Therefore, the amount of spitting scattered vertically upward has increased.

  Next, Examples 1 to 9 will be described. By setting the twist δ to 10 to 60 ° and the cross-sectional area ratio γ to 3.2 to 10%, the amount of spitting loss could be reduced by 0.2% or more. By setting both the torsion δ and the cross-sectional area ratio γ within the appropriate ranges, the jet from the center hole and the jet from the other nozzles interfere moderately, and smooth movement not only in the circumferential direction but also in the radial direction. A pressure distribution was obtained, and as a result, the amount of spitting loss could be significantly reduced.

  From the above results, the upper blow lance for molten metal refining according to the present invention, that is, the twist lance having a twist degree δ of more than 0 and less than 70 ° and a cross-sectional area ratio γ of 3.2% or more and 10% or less is determined. It can be seen that this is the optimal lance for suppressing the amount of ting loss.

DESCRIPTION OF SYMBOLS 1 Lance 2 Nozzle 3 Center hole 4 Bath surface 5 Fire point 6 Droplet 7 Absorbent paper α Nozzle turning angle β Nozzle inclination angle δ Twist degree γ Cross-sectional area ratio D Nozzle outlet and lance center distance H ₀

Claims (1)

XYZ Cartesian coordinates determined so that the center axis of the lance is on the Z axis and the exit position of the nozzle is on the X axis in a metal refining top lance having nozzles with three or more holes arranged at equal intervals on the same circumference In the system, when the angles formed by the projection of the nozzle axis on the YZ plane and the XZ plane with respect to the Z axis are α and β, respectively, α and β satisfy the following formula (1), and the nozzle axis is installed at the center of the nozzle. An upper blow lance for molten metal refining, wherein the ratio γ of the cross-sectional area of the center hole to the total cross-sectional area of the nozzle satisfies the following expressions (2) and (3):
tan10 ° ≦ tanα / tanβ ≦ tan60 ° (1)
3.2 ≦ γ ≦ 10 (2)
γ = (d ₁ ² / (d ₁ ² + n × d ₂ ² )) × 100 (3)
In the formula (3), d ₁ is the diameter (mm) of the center hole, d ₂ is the diameter (mm) of the other hole, n is the number of other holes, and the different-diameter porous where the diameter of the other hole is not constant. In the case of a lance, S is the total cross-sectional area of the nozzle excluding the center hole, and (d ₁ ² + n × d ₂ ² ) in equation (3) is replaced with (d ₁ ² +4 S / π).

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