JP7307305B2 - Gas injection device and gas injection method for electric furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas ejection device and a gas ejection method for an electric furnace.

A known technique is to blow gas containing oxygen into the furnace body from a nozzle hole at the tip of a lance in order to accelerate the melting of solid metal materials charged into the furnace body of an electric furnace and to refine the molten metal material in the furnace body. (See Patent Documents 1 to 3, for example).

In such a technique, when the jet of gas comes into contact with the electrode, the electrode may be worn due to the thermal effect of the jet. Here, in order to avoid wear of the electrode, it is conceivable to eject the jet at a position away from the electrode. parts may be damaged.

Japanese Patent No. 3148966 Japanese Patent No. 2912834 Japanese Patent No. 2824955 JP-A-8-109408

The present invention has been made in view of the above circumstances, and an object of the present invention is to achieve both suppression of electrode wear and suppression of wear of the peripheral wall portion of the furnace body.

A gas ejection device according to an aspect of the present invention is applied to an electric furnace comprising a container-shaped furnace body and a cylindrical electrode arranged vertically in a central portion of the furnace body, wherein the electrode is arranged at a position above the peripheral wall side of the furnace body and above the lower end of the electrode, and the tip is inclined with respect to the vertical direction so as to face the central part side and the lower side of the furnace body, a lance for ejecting oxygen-containing gas into the furnace body from at least one tip nozzle hole in order to accelerate the melting of the solid metal material charged into the furnace body and to refine the molten metal material in the furnace body, Let D _E be the shortest distance in the horizontal direction between the central axis of the gas jet jetted from the tip nozzle hole and the central axis of the electrode, r _E be the radius of the electrode, and the central axis of the jet and the radius along the shortest distance DE in the spread of the jet in the horizontal direction centered on the point on the central axis of the jet where the distance along the horizontal direction from the central axis of the _electrode is the shortest where r _J satisfies the formula (1) and is along the horizontal direction between the center of the fire point, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace body. Let _DW be the shortest distance, and r be the radius along the shortest distance _DW in the spread of the jet in the horizontal direction centering on the center of the ignition point when the jet contacts the bath surface of the molten metal material. When _H , the gas is ejected so as to satisfy the formula (2).
D _E >r _E +r _J (1)
D _W > r _H (2)

According to the gas ejection device according to one aspect of the present invention, the shortest distance along the horizontal direction between the central axis of the jet and the central axis of the electrode is D _E , the radius of the electrode is r _E , and the central axis of the jet is and the radius along the shortest distance _DE in the spread of the jet in the horizontal direction centered on the point on the center axis of the jet where the distance along the horizontal direction with the center axis of the electrode is _the shortest. In this case, the gas is ejected from the tip nozzle hole so as to satisfy the formula (1).
D _E >r _E +r _J (1)

As a result, it is possible to prevent the jet from contacting the electrodes, thereby suppressing wear and tear on the electrodes.

In addition, when the gas is ejected in this way, the shortest distance along the horizontal direction between the center of the ignition point, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace body. _DW , and _rH is the radius along the shortest distance _DW in the spread of the jet in the horizontal direction centering on the fire point center when the jet comes into contact with the bath surface of the molten metal material, the formula ( 2) should be satisfied.
D _W > r _H (2)

As a result, the jet can be prevented from coming into contact with the peripheral wall of the furnace body, and wear of the peripheral wall of the furnace body can be suppressed.

A gas injection method according to an aspect of the present invention is applied to an electric furnace comprising a container-shaped furnace body and a cylindrical electrode arranged vertically in the central part of the furnace body, wherein the electrode is arranged at a position above the peripheral wall side of the furnace body and above the lower end of the electrode, and the tip is inclined with respect to the vertical direction so as to face the central part side and the lower side of the furnace body, A lance for ejecting a gas containing oxygen into the furnace body from at least one tip nozzle hole is used to accelerate the melting of the solid metal material charged into the furnace body and to refine the molten metal material in the furnace body, Let D _E be the shortest horizontal distance between the central axis of the gas jet jetted from the tip nozzle hole and the central axis of the electrode, r _E be the radius of the electrode, and r E be the central axis of the jet. , the radius along the shortest distance DE in the spread of the jet in the horizontal direction centered on the point on the central axis of the jet where the distance along the horizontal direction from the central axis of the _electrode is the shortest (1) is satisfied, and the shortest distance along the horizontal direction between the fire point center, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace _body . Let _DW be the distance, and _rH be the radius along the shortest distance _DW in the spread of the jet in the horizontal direction around the center of the ignition point when the jet comes into contact with the bath surface of the molten metal material. , the gas is jetted so as to satisfy the expression (2).
D _E >r _E +r _J (1)
D _W > r _H (2)

According to the gas ejection method according to one aspect of the present invention, the shortest distance along the horizontal direction between the central axis of the jet and the central axis of the electrode is D _E , the radius of the electrode is r _E , and the central axis of the jet is and the radius along the shortest distance _DE in the spread of the jet in the horizontal direction centered on the point on the center axis of the jet where the distance along the horizontal direction with the center axis of the electrode is _the shortest. In this case, the gas is ejected from the tip nozzle hole so as to satisfy the formula (1).
D _E >r _E +r _J (1)

As a result, it is possible to prevent the jet from contacting the electrodes, thereby suppressing wear and tear on the electrodes.

In addition, when the gas is ejected in this way, the shortest distance along the horizontal direction between the center of the ignition point, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace body. _DW , and _rH is the radius along the shortest distance _DW in the spread of the jet in the horizontal direction centering on the fire point center when the jet comes into contact with the bath surface of the molten metal material, the formula ( 2) should be satisfied.
D _W > r _H (2)

As a result, the jet can be prevented from coming into contact with the peripheral wall of the furnace body, and wear of the peripheral wall of the furnace body can be suppressed.

According to one aspect of the present invention, it is possible to achieve both suppression of electrode wear and suppression of wear of the peripheral wall portion of the furnace body.

FIG. 3 is a plan view showing the positional relationship between the lance and the electrodes of the gas ejection device according to one embodiment of the present invention; 1 is a side cross-sectional view showing the overall configuration of an electric furnace to which a gas ejection device according to one embodiment of the present invention is applied; 1 is a perspective view showing a positional relationship between a lance, a peripheral wall portion of a furnace body, and an electrode of a gas ejection device according to an embodiment of the present invention; FIG. FIG. 4 is a plan view of FIG. 3; 1 is a plan view showing a first example of a gas ejecting device according to an embodiment of the present invention when formulas (1) and (2) are satisfied; FIG. FIG. 5 is a plan view showing a second example of the gas ejection device according to one embodiment of the present invention in which formulas (1) and (2) are satisfied; FIG. 10 is a plan view showing a third example of the gas ejection device according to one embodiment of the present invention, which satisfies formulas (1) and (2). FIG. 6 is a plan view showing a comparative example in which the gas ejection device according to one embodiment of the present invention does not satisfy the formula (1). FIG. 10 is a plan view showing a comparative example in which the gas ejection device according to one embodiment of the present invention does not satisfy Expression (2).

An embodiment of the present invention will be described below.

As shown in FIG. 2 (see also FIG. 1 as appropriate), a gas ejection device 10 (a gas ejection device for an electric furnace) according to one embodiment of the present invention is applied to an electric furnace 30 . The electric furnace 30 includes a container-shaped furnace body 32 that opens upward, and a columnar electrode 34 that is vertically arranged in the center of the furnace body 32 . A solid metallic material 36 and a molten metallic material 38 are charged in the furnace body 32 . In this embodiment, as an example, the solid metallic material 36 is iron scrap and the molten metallic material 38 is hot metal. The electrode 34 is arranged at a height such that the tip thereof faces the bath surface 38A of the molten metal material 38 . A surface layer portion of the electrode 34 is made of, for example, graphite.

The gas ejection device 10 has a straight round bar-shaped lance 12 and a gas supply section 14 for supplying gas to the lance 12 . The lance 12 is inserted into the furnace body 32 from, for example, the upper portion of the peripheral wall portion 32A of the furnace body 32 or the peripheral edge portion of a cover (not shown) provided on the upper side of the furnace body 32, thereby allowing the furnace body 32 to move closer to the furnace than the electrode 34. It is arranged on the peripheral wall portion 32A side of the body 32 and above the lower end of the electrode 34 . The lance 12 is of a water-cooled type that is water-cooled by circulating water. The lance 12 is inclined with respect to the vertical direction so that the tip 12A faces toward the central portion of the furnace body 32 and downward.

At least one tip nozzle hole 16 is formed in the tip 12A of the lance 12 . For example, one, two, three, or four tip nozzle holes 16 may be formed at the tip 12A of the lance 12 . As shown in FIG. 1, in this embodiment, as an example, two tip nozzle holes 16 are formed at the tip 12A of the lance 12. As shown in FIG. These two tip nozzle holes 16 are arranged symmetrically with respect to the central axis A2 of the lance 12 in plan view.

A central axis A1 of the tip nozzle hole 16 forms an acute angle with a central axis A2 of the lance 12 in plan view. Hereinafter, the angle formed by the central axis A1 of the tip nozzle hole 16 and the central axis A2 of the lance 12 in plan view will be referred to as a nozzle angle α. Further, as shown in FIG. 2, the center axis A1 of the tip nozzle hole 16 forms an acute angle with the horizontal direction when viewed from the side. Hereinafter, the inclination angle of the center axis A1 of the tip nozzle hole 16 with respect to the horizontal direction is referred to as a nozzle angle β.

In the gas ejection device 10, when the gas supply unit 14 is activated to promote the dissolution of the solid metal material 36 and to refine the molten metal material 38, the gas is supplied from the gas supply unit 14 to the lance 12, and the tip nozzle A gas containing oxygen is ejected from the hole 16 into the furnace body 32 .

By the way, when the gas is ejected from the tip nozzle hole 16 in this way, if the gas jet comes into contact with the electrode 34, the electrode 34 may be worn due to the thermal effect of the jet. Here, in order to avoid wear of the electrode 34, it is conceivable to eject the jet at a position away from the electrode 34. In this case, the jet contacts the peripheral wall portion 32A of the furnace body 32, There is a possibility that the peripheral wall portion 32A of the furnace body 32 is worn.

Here, the inventors conducted an experiment using a DC electric furnace 30 with a steel output of 100 tons. First, 65 tons of scrap was charged into the electric furnace 30, and about 30 to 40% of the scrap was melted. A water-cooled lance 12 is inserted into the furnace body 32 from the operation port at the top of the furnace body 32, and oxygen necessary for desiliconization, decarburization, and dephosphorization is supplied to hot metal and unmelted scrap at a rate of 6000 Nm ³ /hr. , and the composition of the molten steel after oxygen feeding was adjusted to C: 0.1% or less and P: 0.015% or less. During the treatment, the distance between the tip 12A of the lance 12 and the bath surface 38A (apparent hot metal surface) was appropriately controlled within the range of 0.1 to 3.0 m.

Then, in the above process, conditions for achieving both suppression of wear of the electrode 34 and suppression of wear of the peripheral wall portion 32A of the furnace body 32 were earnestly studied. As a result, we thought that the following conditions were necessary.

(Conditions for Suppressing Wear of Electrodes 34)
First, conditions for suppressing wear of the electrode 34 will be described. FIG. 3 shows the positional relationship between the lance 12, the peripheral wall portion 32A of the furnace body 32, and the electrode 34, and FIG. 4 is a plan view of FIG. In this study, for the sake of convenience, only one tip nozzle hole 16 of the two tip nozzle holes 16 (see FIG. 1) will be focused on. In this study, the shortest horizontal distance between the central axis A3 of the gas jet 18 and the central axis A4 of the electrode 34 is defined as _DE . Also, as shown in FIG. 4, the radius of the electrode 34 is _rE . Also, let E be a point on the central axis A3 of the jet 18 where the distance along the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is the shortest. Furthermore, the radius along the shortest distance D _E in the spread of the jet 18 in the horizontal direction centered on the point E is r _J . When the ignition point center O is on the opposite side of the lance 12 from the electrode 34 (see FIG. 4), the point E is located on the lance 13 side of the ignition point center O. In this case, the expanding shape of the jet 18 in the horizontal direction centering on the point E is circular. On the other hand, when the ignition point center O is closer to the lance 12 than the electrode 34, the point E coincides with the ignition point center O (see FIG. 5, which will be described later). In this case, the shape of the horizontal spread of the jet 18 centered on the point E is the same as the shape of the horizontal spread of the jet 18 centered on the firing point O, and is thus elliptical. Then, in order to suppress the wear of the electrode 34, it was thought that the gas should be ejected from the tip nozzle hole 16 so as to satisfy the expression (1). If this formula (1) is satisfied, the jet 18 does not come into contact with the electrode 34, and wear of the electrode 34 can be suppressed.
D _E >r _E +r _J (1)

(Conditions for suppressing wear of the peripheral wall portion 32A of the furnace body 32)
Next, conditions for suppressing wear of the peripheral wall portion 32A of the furnace body 32 will be described. In this study, _DW is the shortest distance along the horizontal direction between the fire point center O, which is the intersection of the central axis A3 of the jet 18 and the bath surface 38A of the molten metal material 38, and the peripheral wall 32A of the furnace body 32. do. Also, let O be the center of the ignition point when the jet 18 contacts the bath surface 38A of the molten metal material 38 . Furthermore, let _rH be the radius along the shortest distance _DW in the spread of the jet 18 in the horizontal direction centering on the ignition point O. The expanding shape of the jet 18 in the horizontal direction around the ignition point O is elliptical. Then, in order to suppress the wear of the peripheral wall portion 32A of the furnace body 32, it was thought that the gas should be ejected from the tip nozzle hole 16 so as to satisfy the expression (2). If this formula (2) is satisfied, the jet 18 does not contact the peripheral wall portion 32A of the furnace body 32, and wear of the peripheral wall portion 32A of the furnace body 32 can be suppressed.
D _W > r _H (2)

ただし、ａは楕円の長辺の長さ［ｍ］、ＬＨはランス高さ［ｍ］、ｂは楕円の短辺の長さ［ｍ］、φは噴流１８の中心軸Ａ３と最短距離Ｄ_Ｅに沿った線分が成す角度である。
（Ｃ）「水平方向への噴流１８の拡がりにおける最短距離Ｄ_Ｗに沿った半径ｒ_Ｈ」は、噴流１８の直進距離をＬとした場合に、Ｌ×ｔａｎθ／ｓｉｎ（β－θ）で求められるものとする。ただし、θは、噴流１８の拡がり角度であり、ここでは、１５°とする。
（Ｄ）「溶融金属材料３８の浴面３８Ａ」は、１処理毎の平均総装入量の固体金属材料３６及び溶融金属材料３８が全て溶融したと仮定したときの静止溶融材料面とする。
（Ｅ）「溶融金属材料３８の浴面３８Ａの形状」は、炉体３２の周壁部３２Ａの内径Ｒと同じ円とする。 Each term in the above conditions is defined as follows.
(A) The “jet stream 18” is assumed to advance straight in parallel with a straight line extending from the center axis A1 of the tip nozzle hole 16 .
(B) “Radius r _J along the shortest distance D _E in the spread of the jet 18 in the horizontal direction” is , the shape of the horizontal spread of the jet 18 centered on the point E is circular. However, θ is the divergence angle of the jet 18 and is set to 15° here. On the other hand, when the ignition point center O is closer to the lance 12 than the electrode 34 (see FIG. 5), the shape of the jet 18 extending in the horizontal direction around the point E is elliptical. In this case, the shortest distance _DE corresponds to the distance between the center axis A4 of the electrode 34 and the center O of the ignition point. The radius _rJ corresponds to the distance between the ignition point center O and the intersection of the line segment connecting the ignition point center O and the central axis A4 of the electrode 34 and the ellipse. The shortest distance D _E ′ corresponds to the shortest distance between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 . In this case, "the radius r _J along the shortest distance D _E in the spread of the jet 18 in the horizontal direction" shall be obtained by the following equation.

where a is the length of the long side of the ellipse [m], LH is the lance height [m], b is the length of the short side of the ellipse [m], and φ is the shortest distance from the central axis A3 of the jet 18 to D _E is the angle formed by a line segment along
(C) “Radius r _H along the shortest distance D _W in the spread of the jet 18 in the horizontal direction” is obtained by L×tan θ/sin (β−θ), where L is the straight-ahead distance of the jet 18. shall be provided. However, θ is the divergence angle of the jet 18 and is set to 15° here.
(D) "Bath surface 38A of molten metal material 38" is the static molten material surface assuming that the average total charge of solid metal material 36 and molten metal material 38 per process has all melted.
(E) “The shape of the bath surface 38A of the molten metal material 38” is the same circle as the inner diameter R of the peripheral wall 32A of the furnace body 32 .

By the way, in the above definition, the spreading angle θ of the jet 18 is set to 15°, and the grounds for this are as follows. That is, the divergence angle θ of the jet 18 is said to be 8 to 12° according to a fluid visualization experiment. However, when the divergence angle .theta. of the jet 18 was estimated to be 12.degree. From this, it was found that the heat-affected zone of the jet 18 is affected to the outside of the spread range of the jet 18 . Therefore, when the range of influence was experimentally estimated, θ=15°, which was adopted.

Next, an example of a gas jetting method according to an embodiment of the present invention will be described.

A gas ejection method according to the present embodiment (a gas ejection method for an electric furnace) is performed using the gas ejection device 10 described above. In this example, for the sake of convenience, only one tip nozzle hole 16 of the two tip nozzle holes 16 (see FIG. 1) is focused, but the other tip nozzle hole 16 is also supplied with gas in the same manner as described below. It should squirt out. Moreover, even when the number of tip nozzle holes 16 is three or more, gas may be ejected from each tip nozzle hole 16 in the same manner as described below.

In the gas ejection method according to this embodiment, as shown in FIGS. 3 and 4, first, three-dimensional coordinates are set in the gas ejection device 10 as follows. That is, let the center of the bath surface 38A be the origin (0, 0, 0) of the three-dimensional coordinates. The positive side of the Z-axis is the upper side in the vertical direction. The Y-axis is parallel to a line obtained by projecting the central axis A2 of the lance 12 onto the bath surface 38A, and the side away from the lance 12 is the plus side. The X-axis is perpendicular to the Y-axis when viewed from above in the vertical direction, and the side away from the lance 12 is the positive side.

The lance 12 moves up and down along the axial direction of the lance 12 . Let the upper limit coordinates of the tip nozzle hole 16 be (X _U , _YU , Z _U ) and the lower limit coordinate of the tip nozzle hole 16 be ( _XL , _YL , Z _L ). The coordinates of the tip nozzle hole 16 are based on the opening center of the tip nozzle hole 16 . Since the lance 12 is inclined with respect to the Z-axis (vertical direction), the Y coordinate changes as the lance 12 moves up and down. A central axis A4 of the electrode 34 coincides with the Z-axis. The nozzle angle α (see FIG. 4) corresponds to the angle [deg] formed by the straight line extending from the center axis A1 of the tip nozzle hole 16 and the YZ plane, and the nozzle angle β (see FIG. 3) is the angle of the tip nozzle hole 16. It corresponds to the angle [deg] formed by the straight line extending the central axis A1 and the XY plane.

Then, when the three-dimensional coordinates are set as described above, the conditions shown in the above equations (1) and (2) are determined. That is, by setting the height H of the tip nozzle hole 16 (the height from the bath surface 38A to the opening center of the tip nozzle hole 16 as shown in FIG. 3) at an arbitrary position, the tip nozzle hole 16 can be Coordinates (X, Y, Z) are determined. From the coordinates (X, Y, Z) of the tip nozzle hole 16, the nozzle angle α (see FIG. 4), and the nozzle angle β (see FIG. 3), the coordinates (x, y, z) of the ignition point center O are decide.

Also, from the coordinates (X, Y, Z) of the tip nozzle hole 16 and the coordinates (x, y, z) of the ignition center O, the direction vector of the central axis A3 of the jet 18 ejected from the tip nozzle hole 16 is is determined, and a linear vector formula for the central axis A3 of the jet 18 is obtained. The direction vector of the central axis A4 of the electrode 34 is (0, 0, 1) and passes through the origin, so the linear vector formula of the central axis A4 of the electrode 34 is self-explanatory. The shortest horizontal distance _DE between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is obtained from these two linear vector equations. In this example, the central axis A4 of the electrode 34 passes through the center of the bath surface 38A, but may pass through a position off the center of the bath surface 38A.

In addition, before obtaining the shortest distance D _E along the horizontal direction, the distance along the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is the shortest on the central axis A3 of the jet 18 The coordinates ( _XE , _YE , _ZE ) of point E are obtained. As a result, the distance _LE between the coordinates (X, Y, Z) of the tip nozzle hole 16 and the coordinates ( _XE , _YE , _ZE ) of the point _E is obtained. , (3), the radius r _J along the shortest distance D _E in the spread of the jet 18 in the horizontal direction centered on the point E can be obtained.
r _J =L _E ×tan θ (3)

Then, by combining the radius _{rE of} the electrode 34, which is obtained in advance as an equipment condition, and the radius _rJ along the shortest distance DE in the spread of the jet 18 in the horizontal direction, the above equation (1) is obtained. , determine the conditions for suppressing the wear of the electrode 34 . That is, the shortest distance _DE should be longer than the sum of the radius _rE and the radius _rJ .

Also, the distance L _O between the coordinates (X, Y, Z) of the tip nozzle hole 16 and the coordinates (x, y, z) of the ignition point center _O is obtained. A radius _rH along the shortest distance _DW in the spread of the jet 18 in the horizontal direction centered on is determined. As a result, the coordinates (x, y, z) of the ignition point center O, the coordinates (0, 0, 0) of the center of the bath surface 38A, and the inner diameter R of the peripheral wall portion 32A of the furnace body 32 obtained in advance as the equipment conditions. , the shortest distance D _W along the horizontal direction between the firing point center O and the peripheral wall portion 32A of the furnace body 32 (the circle on the XY plane with the radius R centered on the origin and the firing point center O on the XY plane (shortest distance along the horizontal direction) is obtained.

Then, with the radius _rH along the shortest distance _DW in the spread of the jet 18 in the horizontal direction and the shortest distance _DW along the horizontal direction, the furnace Conditions for suppressing wear of the peripheral wall portion 32A of the body 32 are determined. That is, the shortest distance _DW should be longer than the radius _rH .

In the gas ejection device 10 according to the present embodiment, the nozzle angle α (see FIG. 4), the nozzle angle β (see FIG. 3), and Radius r _J along the shortest distance D _E in the spread of the jet in the horizontal direction around the point E and along the shortest distance D _W in the spread of the jet 18 in the horizontal direction around the center O of the firing point Radius _rH is set. That is, the orientation of the tip nozzle hole 16 is set so that the nozzle angles α and β satisfy the conditions shown in the above equations (1) and (2). Further, the opening area of the tip nozzle hole 16 and the flow rate of the gas injected from the tip nozzle hole 16 are determined so that the radius _rJ and the radius _rH that satisfy the conditions shown in the above formulas (1) and (2) are obtained. etc. are set.

Then, in the gas ejection method according to the present embodiment, gas is ejected from the tip nozzle hole 16 so as to simultaneously satisfy the conditions shown in the above formulas (1) and (2).

Here, FIGS. 5 to 9 show a plurality of examples when the height of the lance 12, the nozzle angle α, and the nozzle angle β are varied. In the examples shown in FIGS. 5 to 9, other conditions (the opening area of the tip nozzle hole 16, the flow rate of the gas injected from the tip nozzle hole 16, etc.) are the same.

First, an example that does not satisfy formula (1) will be described. FIG. 8 shows, as a comparative example, an example in which the formula (1) is not satisfied. That is, in the example shown in FIG. 8, D _E <r _E +r _J. In this case, the jet 18 may come into contact with the electrode 34 and the electrode 34 may be worn due to the thermal effect of the jet 18 .

Next, an example that does not satisfy Expression (2) will be described. FIG. 9 shows, as a comparative example, an example in which Expression (2) is not satisfied. That is, in the example shown in FIG. 9, the jet 18 is ejected at a position away from the electrode 34 in order to avoid wear of the electrode 34, but D _W <r _H. In this case, the jet flow 18 may come into contact with the peripheral wall portion 32A of the furnace body 32, and the peripheral wall portion 32A of the furnace body 32 may be worn.

Next, an example that satisfies formulas (1) and (2) will be described as an example. In the example shown in FIG. 5, the height of the lance 12 is lowered with respect to the example shown in FIG. In the example shown in FIG. 5, the spark point center O is positioned closer to the lance 12 than the central axis A4 of the electrode 34 in plan view. As a result, the point E on the central axis A3 of the jet 18 where the distance along the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is the shortest coincides with the center O of the firing point. . The shortest distance _DE is the distance in the horizontal direction between the ignition point center O and the central axis A4 of the electrode 34 . In the example shown in FIG. 5, D _E >r _E +r _J and D _W >r _H , satisfying the conditions shown in the above equations (1) and (2) at the same time.

In the example shown in FIG. 6, the nozzle angle α is enlarged with respect to the example shown in FIG. In the example shown in FIG. 6, the ignition point center O is located closer to the peripheral wall 32A side of the furnace body 32 than the central axis A4 of the electrode 34 in plan view. In the example shown in FIG. 6, D _E >r _E +r _J and D _W >r _H , satisfying the conditions shown in the above equations (1) and (2) at the same time.

In the example shown in FIG. 7, the nozzle angle β (see FIG. 3) is enlarged with respect to the example shown in FIG. In the example shown in FIG. 7, similarly to the example shown in FIG. 5, the spark point center O is positioned closer to the lance 12 than the central axis A4 of the electrode 34 in plan view. As a result, the point E on the central axis A3 of the jet 18 where the distance along the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is the shortest coincides with the center O of the firing point. . The shortest distance _DE is the distance in the horizontal direction between the ignition point center O and the central axis A4 of the electrode 34 . In the example shown in FIG. 7, D _E >r _E +r _J and D _W >r _H , which simultaneously satisfy the conditions shown in the above equations (1) and (2).

As described above, under the condition expressed by the above formula (1), the larger the nozzle angle α, the further the central axis A3 of the jet 18 is from the electrode 34, which increases the shortest distance _DE . Interference between the influence range and the electrode 34 becomes less likely. Further, the radius _rJ increases as the height of the lance 12 increases, and the influence range of the jet 18 tends to interfere with the _electrode 34. and the electrode 34 are less likely to interfere with each other.

Regarding the condition expressed by the above formula (2), as the nozzle angle β increases, the central axis A3 of the jet 18 moves away from the peripheral wall 32A of the furnace body 32, and the shortest distance _DW increases. The influence range and the peripheral wall portion 32A of the furnace body 32 are less likely to interfere with each other. Also, as the height of the lance 12 increases, the radius _rH increases, and the influence range of the jet 18 tends to interfere with the electrode 34. However, if the nozzle angle β increases, the shortest distance _DW increases. and the peripheral wall portion 32A of the furnace body 32 are unlikely to interfere with each other.

Next, the action and effect of one embodiment of the present invention will be described.

As described in detail above, according to this embodiment, the shortest distance along the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 is D _E , and the radius of the electrode 34 is r _E. , the shortest distance in the horizontal direction between the central axis A3 of the jet 18 and the central axis A4 of the electrode 34 in the horizontal direction centering on the point E on the central axis A3 of the jet 18. Gas is ejected from the tip nozzle hole 16 so as to satisfy the formula (1), where _rJ is the radius along the distance _DE .
D _E >r _E +r _J (1)

As a result, the jet 18 can be prevented from contacting the electrode 34, and wear of the electrode 34 can be suppressed.

In this way, when the gas is jetted out, the horizontal line between the fire point center O, which is the intersection of the central axis A3 of the jet stream 18 and the bath surface 38A of the molten metal material 38, and the peripheral wall portion 32A of the furnace body 32 The shortest distance along the direction is _DW , and the shortest distance _DW in the spread of the jet 18 in the horizontal direction centered on the ignition point O when the jet 18 contacts the bath surface 38A of the molten metal material 38. (2) is satisfied, where _rH is the radius.
D _W > r _H (2)

As a result, the jet 18 can be prevented from coming into contact with the peripheral wall portion 32A of the furnace body 32, so that the wear of the peripheral wall portion 32A of the furnace body 32 can be suppressed.

Thus, according to this embodiment, it is possible to achieve both suppression of wear of the electrode 34 and suppression of wear of the peripheral wall portion 32A of the furnace body 32 .

Next, verification tests conducted on examples of one embodiment of the present invention and comparative examples will be described.

Table 1 shows the results of verification tests conducted on examples and comparative examples of one embodiment of the present invention. "Electrode wear index" represents the ratio of electrode wear based on "Comparative Example 1", and "Furnace wall wear index" represents the wear rate of the peripheral wall of the furnace body based on "Comparative Example 1". represents.

"Condition 1" corresponds to the condition shown in formula (1), and "Condition 2" corresponds to the condition shown in formula (2). Regarding "Condition 1" and "Condition 2", "O" indicates that the conditions are satisfied, and "X" indicates that the conditions are not satisfied. "Evaluation" corresponds to whether or not the electrode wear index and furnace wall wear index satisfy predetermined values. Regarding "Evaluation", "○" indicates that the electrode wear index and the furnace wall wear index satisfy the predetermined values, and "X" indicates that the electrode wear index and the furnace wall wear index do not satisfy the predetermined values. represent.

As shown in Table 1, in "Comparative Example 1" to "Comparative Example 6", either "Condition 1" or "Condition 2" is "x", so the "evaluation" is also "x". . On the other hand, in "Example 1" to "Example 9", "Condition 1" and "Condition 2" are both "○", so the "Evaluation" is also "○". Thus, the usefulness of one embodiment of the present invention could be confirmed from the results of the verification test.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and it goes without saying that various modifications can be made in addition to the above without departing from the scope of the invention. is.

10 gas ejection device 12 lance 16 tip nozzle hole 18 jet 30 electric furnace 32 furnace body 32A peripheral wall 34 electrode 36 solid metal material 38 molten metal material 38A bath surface A1 tip nozzle hole central axis A2 lance central axis A3 jet center Axis A4 the central axis of the electrode

Claims (2)

a container-shaped furnace body;
a cylindrical electrode arranged along the vertical direction in the central part of the furnace body;
applied to electric furnaces with
It is arranged at a position closer to the peripheral wall of the furnace body than the electrode and above the lower end of the electrode, and is inclined with respect to the vertical direction so that the tip points toward the central part of the furnace body and downward. It ascends and descends along the axial direction, with the tip facing the electrode in a plan view, for accelerating the melting of the solid metal material charged into the furnace body and for refining the molten metal material in the furnace body, having a lance for ejecting oxygen-containing gas into the furnace body from a plurality of tip nozzle holes,
Let _DE be the shortest distance along the horizontal direction between the central axis of the gas jet jetted from the tip nozzle hole and the central axis of the electrode,
Let the radius of the electrode be r _E ,
The shortest distance DE in the spread of the jet in the horizontal direction centered on a point on the central axis of the jet where the distance along the horizontal direction between the central axis of the jet and the central axis of the electrode _is the shortest satisfies equation (1), where r _J is the radius along
D _E >r _E +r _J (1)
Let _DW be the shortest distance in the horizontal direction between the center of the ignition point, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace body,
When the radius along the shortest distance _DW in the spread of the jet in the horizontal direction centering on the fire point center when the jet comes into contact with the bath surface of the molten metal material is _rH , the formula ejecting the gas so as to satisfy (2);
D _W > r _H (2)
Gas ejection device in an electric furnace. a container-shaped furnace body;
a cylindrical electrode arranged along the vertical direction in the central part of the furnace body;
applied to electric furnaces with
It is arranged at a position closer to the peripheral wall of the furnace body than the electrode and above the lower end of the electrode, and is inclined with respect to the vertical direction so that the tip points toward the central part of the furnace body and downward. It ascends and descends along the axial direction, with the tip facing the electrode in a plan view, for accelerating the melting of the solid metal material charged into the furnace body and for refining the molten metal material in the furnace body, Using a lance that ejects oxygen-containing gas into the furnace body from a plurality of tip nozzle holes,
Let _DE be the shortest distance along the horizontal direction between the central axis of the gas jet jetted from the tip nozzle hole and the central axis of the electrode,
Let the radius of the electrode be r _E ,
When the distance along the horizontal direction between the central axis of the jet and the central axis of the electrode is the shortest, and the radius along the shortest distance _DE in the spread of the jet in the horizontal direction is _rJ , satisfies the formula (1),
D _E >r _E +r _J (1)
Let _DW be the shortest distance in the horizontal direction between the center of the ignition point, which is the intersection of the central axis of the jet and the bath surface of the molten metal material, and the peripheral wall of the furnace body,
When the radius along the shortest distance _DW in the spread of the jet in the horizontal direction centering on the fire point center when the jet comes into contact with the bath surface of the molten metal material is _rH , the formula ejecting the gas so as to satisfy (2);
D _W > r _H (2)
Gas injection method in electric furnace.

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