JP6201971B2 - How to cut the bullion of the converter - Google Patents

Description

  The present invention relates to a furnace mouthpiece for a converter and a method for cutting a metal.

  In the steelmaking process of steelworks, a converter is used as a refining facility for oxidizing and refining hot metal. When performing blow smelting treatment, which is oxidative refining, in the converter, bullion scattered from the steel bath inside the converter adheres to the furnace port of the converter and the skirt of the exhaust gas duct. Furthermore, by repeating the blowing process, the accumulation of metal at the furnace port and the skirt portion proceeds. The bullion deposited at the furnace opening hinders each processing operation when the acid is fed into the furnace or when the auxiliary material is added. Moreover, if the metal deposited on the skirt portion is connected to the metal deposited on the furnace port, the tilting operation of the converter furnace body is hindered. For this reason, the operation | work which strips off the metal | bulb adhering to a furnace port or a skirt part using a scrap chute | shoot etc. between blowing processes is performed.

In addition, as a method for preventing the adhesion of metal to the vicinity of the furnace opening and melting and removing the metal that has adhered to the vicinity of the furnace opening, a gas injection nozzle is provided on the circumference in the gap between the converter furnace opening and the upper skirt. A method is known in which an inert gas is ejected from a nozzle during blowing and oxygen gas is ejected from the nozzle after blowing (Patent Document 1).
Furthermore, as a method for melting and removing the metal bar attached to the furnace port and the inside of the converter, a method is known in which oxygen gas is injected and removed from the tip of the lance inserted into the furnace from the furnace port ( Patent Document 2).
Furthermore, as a method of efficiently suppressing the adhesion of the furnace mouth bullion while suppressing damage to the furnace refractory, oxygen from the metal melting nozzle provided in the lance for blowing during the first half of the blowing period. A method is known in which purge gas is supplied from a nozzle for melting a metal in the later stage of the blowing period (Patent Document 3).

JP-A-11-264909 JP-A-11-350015 JP 2000-96119 A

Here, in a normal converter structure, there is a case in which the bullion attached to and deposited on the furnace mouth metal provided in the furnace throat is connected to the bullion attached to and deposited in the furnace. In such a case, the method of stripping the metal from the furnace port using a scrap chute makes it difficult to sufficiently remove the metal from the furnace port, which increases the time required for removing the metal. Was a problem.
Further, in the method described in Patent Document 1, the number of nozzles on the side portion of the furnace mouth metal and the injection condition of the inert gas are not clarified, and blockage due to the accumulation of metal at the nozzle outlet or between the nozzles. May occur. For this reason, when metal deposits occur at the nozzle outlet or between the nozzles, the metal that adheres or accumulates on the furnace mouth metal and the metal that adheres or accumulates in the furnace are connected, which can be used to remove the metal. The problem was that the time required increased.

Furthermore, in the methods described in Patent Documents 2 and 3, since there is a concern about melting of the furnace mouth metal by the oxygen gas injected to dissolve the metal, it is possible to dissolve the metal attached near the furnace mouth. It was difficult. For this reason, the bullion attached / deposited to the furnace mouth metal and the bullion attached / deposited in the furnace are connected to each other, and it takes a long time to remove the bullion.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and it is possible to shorten the time required for removing the metal that has adhered to the furnace port of the converter. The purpose is to provide hardware and bullion cutting methods.

In order to achieve the above object, a furnace mouthpiece of a converter according to an aspect of the present invention has a plurality of nozzles on a surface facing the central axis of the converter, and the converter is moved in a direction from the nozzle toward the central axis. An inert gas is ejected from the nozzle at an injection speed equal to or higher than the superficial velocity at the furnace port of the converter calculated from the exhaust gas flow rate of the furnace and the diameter of the furnace port.
Further, a method for cutting a metal bar of a converter according to an aspect of the present invention includes a plurality of nozzles provided on a surface facing the central axis of the converter, at least during the blowing process of the converter, from the nozzle to the central axis. The inert gas is jetted at a jetting speed equal to or higher than the superficial velocity at the furnace port of the converter, which is calculated from the exhaust gas flow rate of the converter and the diameter of the furnace port.

  According to the furnace metal fitting and the metal cutting method according to the present invention, it is possible to shorten the time required to remove the metal attached to the furnace furnace opening.

It is explanatory drawing which shows the structure of the converter which concerns on one Embodiment of this invention. It is a top view which shows a furnace mouth metal fitting. It is a top view which shows a part of furnace mouth metal fitting. It is the II arrow directional view of FIG. It is the II-II arrow directional view of FIG. It is the III-III arrow directional view of FIG. It is sectional drawing which shows the adhesion state of the base metal of a furnace mouth metal fitting.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.
<Composition of furnace fitting>
First, with reference to FIGS. 1-6, the structure of the furnace mouthpiece 4 of the converter 1 which concerns on one Embodiment of this invention is demonstrated. As shown in FIG. 1, the converter 1 includes a metal furnace body 2, a refractory 3, a furnace mouthpiece 4, a bottom blowing nozzle 5, a lance 6, a skirt portion 7, and a hood 8. Prepare.

The furnace body 2 has a pear-shaped shape with an open top, and a refractory 3 is provided on the entire inner wall.
The furnace mouth metal 4 is provided so as to cover the outer periphery of a circular furnace mouth which is an open end of the upper part of the furnace body 2 and the refractory 3 and protects the furnace body 2 and the refractory 3. As shown in FIG. 2, the furnace mouthpiece 4 includes eight fan-shaped furnace mouthpiece members 4 a to 4 h, and the outer periphery of the furnace mouth is in a state where the furnace mouthpiece members 4 a to 4 h are arranged adjacent to each other. Is provided. In the center of the furnace mouthpiece 4, a circular opening is formed corresponding to the opening end of the furnace mouth. Hereinafter, the surface on the opening side of the furnace mouthpiece 4 and facing the central axis of the furnace body 2 shown by the one-dot chain line in FIG. 1 is referred to as a furnace mouth inner surface 40a (40).

As shown in FIGS. 3 to 6, the furnace mouthpiece member 4 a includes a gas supply pipe 41 a (41), a header pipe 42 a (42), a plurality of gas supply paths 43 a (43), and a plurality of nozzles 44 a ( 44).
The gas supply piping 41a is provided from the outer peripheral direction of the furnace port to the inside of the furnace port metal member 4a. One end of the gas supply pipe 41a inside the furnace mouthpiece member 4a is connected to the header pipe 42a. The other end of the gas supply pipe 41a is connected to a gas supply device (not shown).
The header pipe 42a is provided in the furnace port metal member 4a so as to extend in the circumferential direction of the furnace port. The header pipe 42a is connected to one end of the gas supply pipe 41a and the plurality of gas supply paths 43a, and supplies an inert gas sent from the gas supply apparatus through the gas supply pipe 41a to the plurality of gas supply paths 43a. Nitrogen gas, argon gas, or the like is used as the inert gas.

The gas supply paths 43a are holes that connect the header pipe 42a and the nozzles 44a, and are provided in the same number as the nozzles 44a.
The nozzle 44a extends from the gas supply path 43a to the furnace port inner surface 40a (40). The nozzle 44a injects the inert gas supplied from the gas supply path 43a from the furnace port inner surface 40a. Further, 20 nozzles 44a are provided side by side at substantially equal intervals in the direction in which the header pipe 42a extends. The tip of each nozzle 44a on the furnace port inner surface 40a side is provided so as to be substantially staggered in two rows in the vertical direction with respect to the furnace port inner surface 40a. That is, as shown in FIG. 5, the adjacent nozzles 44a are arranged such that the tips on the furnace inner surface 40a side of the nozzles 44a excluding the two nozzles 44 at the center are vertically above the furnace inner surface 40a. They are offset from each other. Among these, as shown in FIG. 4, the nozzle 44a whose tip is disposed below the furnace port inner surface 40a is provided to extend in the horizontal direction from the header pipe 42a. Further, as shown in FIG. 6, the nozzle 44a whose tip is disposed above the furnace port inner surface 40a is provided to extend from the header pipe 42a with an inclination with respect to the horizontal direction.

The furnace mouthpiece member 4a having the above-described configuration is formed by providing a plurality of holes from the furnace mouth inner surface 40a to the header pipe 42a after the gas supply pipe 41a and the header pipe 42a are cast into the furnace mouthpiece member 4a. The supply path 43a is formed, and the nozzles 44a are embedded in the formed holes, respectively.
The furnace mouth metal members 4b to 4h have the same shape and configuration as the furnace mouth metal member 4a. That is, each of the furnace mouthpiece members 4b to 4h includes a gas supply pipe 41, a header pipe 42, a plurality of gas supply paths 43, and a plurality of nozzles 44, similarly to the furnace mouthpiece member 4a.

  The gas injection speed of the inert gas injected from the nozzle 44 is set to be equal to or higher than the superficial speed at the furnace port of the converter 1. The superficial velocity is determined from the flow rate of exhaust gas generated by the blowing process of the converter 1 and the diameter of the furnace port. In the present embodiment, by setting the gas injection speed to be equal to or higher than the superficial velocity, the outlet pressure of the nozzle 44 can be set to be equal to or higher than the superficial pressure, which is the differential pressure between the atmosphere in the furnace and the outside air at the furnace port. .

Furthermore, the furnace mouthpiece 4 formed by the furnace mouthpiece members 4a to 4h has a circumferential occupancy ratio A of the nozzle 44 with respect to the length in the circumferential direction of the furnace mouth inner surface 40 represented by the following equation (1): It is preferably 0.20 or more and 0.90 or less. In equation (1), N is the number (number) of nozzles 44 provided around the circumference of the inner surface 40 of the furnace port, d is the diameter (mm) of the nozzle 44, π is the circumference ratio, and E is the furnace mouth metal. 4 indicates the diameter (mm) of the furnace port whose outer periphery is covered.
A = (N · d) / (π · E) (1)

A plurality of bottom blowing nozzles 5 are provided at the bottom of the furnace body 2 from the outer surface of the furnace body 2 to the inner surface including the refractory 3. The bottom blowing nozzle 5 is made of a refractory in which a plurality of pipes for supplying an inert gas are embedded, and the hot metal M accommodated in the furnace is blown into the furnace of the converter 1 through the pipes. Is allowed to stir.
The lance 6 is provided above the furnace body 2 so as to be movable in the vertical direction, and oxidizes and refines the hot metal M accommodated in the furnace by injecting oxygen gas from the tip.
The skirt portion 7 and the hood 8 are part of an OG facility that collects exhaust gas discharged from the furnace. The skirt portion 7 is formed so as to cover the upper part of the furnace port of the furnace body 2 and is connected to the hood 8. The hood 8 is connected to other OG equipment such as a dust collector.

<How to cut bullion>
Next, with reference to FIG. 7, the metal cutting method of the converter 1 which concerns on one Embodiment of this invention is demonstrated. In the converter 1, the blowing process for carrying out the oxidation refining of the hot metal M accommodated in the furnace is performed. In the blowing process, the hot metal M is oxidized mainly by oxygen gas injected from the tip of the lance 6. At this time, in the furnace, a spitting phenomenon in which the metal such as molten iron M or oxidized molten steel scatters, or a slopping phenomenon in which the slag generated by the process is ejected in a state where the metal is mixed in part. . Ingots scattered by spitting and slopping phenomena (including ingots mixed in slag) adhere and accumulate near the furnace entrance.

  In the present embodiment, the inert gas G is injected from the nozzle 44 of the furnace mouthpiece 4 during the blowing process of the converter 1. At this time, as shown in FIG. 7, the inert gas G is injected from the nozzle 44 toward the central axis of the converter 1, thereby preventing adhesion of the metal around the nozzle 44. For this reason, the metal in the vicinity of the furnace port can be in a state of being cut into the furnace metal ingot S1 attached to the upper part of the furnace port and the furnace metal S2 attached in the furnace.

  The blowing process as described above is performed a plurality of times, and when the furnace opening ingot S1 is deposited to some extent, the removal process of the furnace opening ingot S1 is performed. In the removal process, with the furnace body 2 tilted, the tip of the scrap chute is applied to the furnace mouth metal S1, and the furnace mouth metal S1 is scraped off to remove the furnace mouth metal S1. At this time, since the furnace opening ingot S1 is cut off from the furnace ingot S2, the furnace opening ingot S1 can be easily scraped off.

<Modification>
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the said embodiment, although the inert gas G was injected from the nozzle 44 at the time of the blowing process of the converter 1, this invention is not limited to this example. For example, in the non-blowing process, the inert gas G may be injected from the nozzle 44 as in the blowing process. At this time, the injection speed of the inert gas may be lower than that during the blowing process. By injecting the inert gas G during the non-blowing process, the nozzle 44 is cooled, and the nozzle 44 can be prevented from being melted.

Moreover, in the said embodiment, although the nozzle 44 was provided in the upper and lower two rows with respect to the furnace port inner surface 40, this invention is not limited to this example. As long as the furnace opening ingot S1 and the in-furnace ingot S2 can be cut off at the furnace inner surface 40, one or more nozzles 44 may be provided in the vertical direction of the furnace inner surface 40. At this time, by providing a large number of rows of nozzles 44, an area where the furnace opening metal S1 and the furnace metal S2 are edged increases, so that the edge can be surely cut.
Furthermore, the shape of the cross section perpendicular to the longitudinal direction of the nozzle 44 may have a shape other than a circle such as a rectangle.

<Effect of embodiment>
(1) A furnace mouthpiece for a converter according to an embodiment of the present invention has a plurality of nozzles 44 on a surface 40 facing the central axis of the converter 1, and the converter in a direction from the nozzle 44 toward the central axis. The inert gas G is ejected from the nozzle 44 at an injection speed equal to or higher than the superficial velocity at the furnace port of the converter 1 calculated from the exhaust gas flow rate of 1 and the furnace port diameter.

  Here, in the case of not using the furnace mouthpiece having the above configuration, the furnace mouth ingot S1 and the furnace ingot S2 which are attached and deposited by performing the blowing process are connected to each other, and the furnace mouth ingot using a scrap chute is used. Even if it was going to strip off S1, it was difficult to remove the furnace mouth metal S1 sufficiently. At this time, a method of cutting the edges by fusing the connected furnace ingot S1 and in-furnace ingot S2 can be considered, but since the fusing process takes time, the time required for removing the furnace inlet ingot S1. Becomes longer. Moreover, since these bullion removal operations are performed during the non-blowing process, the time required for the bullion removal becomes longer, and the productivity in the converter 1 is greatly reduced. On the other hand, according to the said structure, the inactive gas G injected can prevent metal adhesion to the nozzle 44 periphery. Thereby, the furnace ingot S1 and the in-furnace ingot S2 can be trimmed, and the deposited furnace mouth ingot S1 can be easily removed, so the time required for removing the ingot attached to the furnace mouth Can be shortened. In addition, since it is not necessary to perform a fusing process for cutting the furnace ingot S1 and the in-furnace ingot S2, it is possible to cause melting damage associated with the fusing process of equipment such as the refractory 3 and the furnace mouth metal 4 of the converter 1. The converter 1 can be used stably.

Moreover, in the invention disclosed in FIG. 3 and FIG. 4 of Patent Document 1, it is necessary to provide a nozzle also on the upper surface side of the furnace mouthpiece, and when the metal attached to the inner surface of the upper hood falls, There was a possibility that the nozzle and piping were damaged. Furthermore, in the invention disclosed in FIGS. 3 and 4 of Patent Document 1, there is a problem that the operating state of the nozzle is deteriorated due to blockage or the like due to the metal falling or depositing on the furnace metal fitting. However, according to the said structure, since the nozzle 44 should just be provided in the furnace opening inner surface 40, even if a base metal falls from the upper part of the furnace opening metal fitting 4, the nozzle 44 and piping will not be damaged. For this reason, the prevention effect of the adhesion of the bullion by the furnace mouthpiece 4 can be stably obtained. Further, even if the metal falls or accumulates on the upper surface of the furnace base metal 4, it does not affect the gas injection operation of the nozzle 44, so that the effect of preventing the adhesion of the metal can be stably obtained.
In the above configuration, when the injection speed of the inert gas is less than the superficial velocity, the scattered metal cannot be blown out sufficiently, so that the metal may adhere to the periphery of the nozzle 44. is there. In such a case, if the furnace opening ingot S1 and the in-furnace ingot S2 are connected, the time required for removing the furnace opening ingot S1 becomes longer.

(2) The plurality of nozzles 44 is defined by the following equation (1), and the circumferential occupation ratio A indicating the occupation ratio of the nozzles 44 with respect to the circumferential length of the surface 40 is 0.20 or more and 0.90 or less. .
A = (N · d) / (π · E) (1)
N: Number of nozzles provided per circumference of the surface facing the central axis of the converter (pieces)
d: Nozzle diameter (mm)
π: Circumference ratio E: Furnace port diameter (mm)

  According to the above-described configuration, it is possible to reliably perform the edge cutting between the furnace port metal S1 and the furnace metal S2 while maintaining the strength of the furnace metal 4 sufficiently. When the circumferential occupancy A is less than 0.20, the metal is not blown off by the inert gas G in the vicinity of the nozzle 44, and thus a region where the metal is attached may occur. For this reason, there is a possibility that a sufficient edge cutting effect cannot be obtained. On the other hand, when the circumferential occupation ratio A is more than 0.90, the ratio of the cavities due to the nozzle 44 and the gas supply path 43 in the furnace mouthpiece 4 becomes excessive. For this reason, the satisfactory mechanical strength of the furnace mouthpiece 4 cannot be obtained.

(3) The nozzles 44 are provided in a plurality of stages in the vertical direction with respect to the surface 40. According to the said structure, since the area | region to cut off the edge of the furnace inlet metal S1 and the furnace inner metal S2 can be enlarged, the edge cutting can be more reliably performed.
(4) The method of cutting the metal in the converter according to the embodiment of the present invention includes a plurality of nozzles 44 provided on the surface facing the central axis of the converter 1 at least during the blowing process of the converter 1. Inert gas is ejected in a direction from the nozzle 44 toward the central axis at an injection speed equal to or higher than the superficial velocity at the furnace port of the converter 1 calculated from the exhaust gas flow rate of the converter 1 and the furnace port diameter. According to the said structure, the effect similar to said (1) can be acquired at the time of a blowing process.
(5) When the converter 1 is not blown, an inert gas is ejected from the nozzle 44. According to the above configuration, wear such as melting of the nozzle 44 can be prevented during the non-blowing process.

  Next, examples performed by the present inventors will be described. In the Example, the furnace mouthpiece 4 which concerns on the said embodiment shown in FIGS. 1-6 was used. The circumferential occupation ratio A of the furnace mouthpiece 4 was set to 0.26. The nozzle 44 and the header pipe 42 having the following specifications were used. In addition, the minimum pitch shown in the specification of the following nozzle 44 shows the shortest distance among the distances in the circumferential direction between adjacent nozzles 44.

[Nozzle specifications]
Material: FCD400
Inner diameter: φ5mm
Spray angle: 90 °
Minimum pitch: 48.2mm
[Header tube specifications]
Material: STS370
Size: 100A x Sch160
Length: 2238mm (40 ° bending)

Moreover, in the Example, nitrogen gas was used as the inert gas injected from the nozzle 44, and the injection speed was set to 17 m / s, which is the same as the calculated superficial velocity at the furnace port of the converter 1. The nitrogen gas injection speed of 17 m / s is 24 Nm ³ / min when converted to the gas flow rate in the standard state of nitrogen gas injected from one furnace end member 4a. Under this condition, the pressure on the outlet side of the nozzle 44 is 10 Pa, which is the same as the set superficial pressure in the furnace. In an Example, the inert gas G was always injected during the blowing process in the converter 1 on said injection conditions.

Furthermore, the lift of the fine bullion generated during the blowing process was calculated from the superficial velocity in the example. The lift L of the fine bullion was calculated using the following equation (2). In the formula (2), L is lift (N), ρ is exhaust gas density (kg / m ³ ), u is dust velocity (m / s), A is a dust representative area (m ² ) that is a spherical projection area, C _D represents the resistance coefficient of spherical dust. The dust velocity was calculated as the same as the superficial velocity.

As a result of calculating the lift L using the equation (2), the lift L was 4.0 × 10 ⁻³ kgf when the particle diameter of the fine metal bar was 2 mm. Since this is an excessive value with respect to the dead weight (0.3 × 10 ⁻³ kgf) of the fine ingot having a particle diameter of 2 mm, the inert gas G is injected from the nozzle 44 at an injection speed higher than the superficial velocity. By doing so, it was confirmed that the bullion scattered to the furnace port could be blown away.

Moreover, as a comparative example with respect to the examples, a blowing operation was performed using a normal furnace mouthpiece, and the working time for removing the bullion per day with the examples was compared. In the comparative example, as a normal furnace mouthpiece, a furnace mouthpiece having no gas supply pipe 41, header pipe 42, gas supply path 43, and nozzle 44 configuration was used. Moreover, when removing the furnace opening ingot in the comparative example, the furnace opening ingot was cut off by melting the furnace opening ingot and the furnace ingot, and then scraped off using the scrap chute. The other conditions were the same as in the example.
As a result of the examples and comparative examples, in the comparative example, the work time for removing the bullion per day for one converter was 157 minutes, whereas in the example, it was 123 minutes, and the furnace mouthpiece of the example and By using the bullion cutting method, it was confirmed that the work time for removing the bullion can be greatly shortened.

1: Converter 2: Furnace 3: Refractory 4: Furnace metal fittings 4a to 4h: Furnace metal fittings 40 and 40a: Furnace inner surface 41 and 41a: Gas supply piping 42 and 42a: Header pipe 43 and 43a: Gas Supply path 44, 44a: Nozzle 5: Bottom blowing nozzle 6: Lance 7: Skirt portion 8: Hood

Claims (1)

During the blowing process of the converter, from the plurality of nozzles provided on the surface facing the central axis of the converter, in the direction from the nozzle toward the central axis, from the exhaust gas flow rate and the furnace port diameter of the converter Injecting an inert gas at an injection speed equal to or higher than the superficial velocity at the furnace outlet of the converter ,
During the non blowing process of the converter, bullion cutting method of the converter, characterized in Rukoto is ejected the inert gas from the nozzle.

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