JPH04308020A - Lance for removing stuck metal to furnace opening part in converter - Google Patents

Abstract

PURPOSE:To efficiently melt a stuck metal to a furnace opening part by providing plural nozzle holes for injecting oxygen on the lower part of a lance. CONSTITUTION:On the lower part of lance 1, plural nozzle holes 8 penetrating cooling water passages 6, 7 and injecting the oxygen, are provided as a radial state. The nozzle holes 8 have the inclination of 0-30 deg. to a horizontal line downward in the injection direction of oxygen. Shape of the nozzle hole is desirably Laval nozzle. Further, it is desirable to protect the lance by making outer face in outer cylinder 2 Cr plating.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special lance for melting and removing bare metal adhering to the mouths of converters by means of oxygen injection.

0002

BACKGROUND OF THE INVENTION In converter steel manufacturing, molten steel is scattered during blowing due to spitting, etc., and this scattered material adheres to the mouth of the converter and solidifies. And this solidified material (base metal)
If it grows and its thickness exceeds a certain limit, it may interfere with the charging of hot metal or scrap, and sometimes it may flake off and fall, causing sudden disturbances in refining due to a drop in temperature. It may also damage the refractories of the furnace. Therefore,
When the thickness of the metal reaches a certain limit, the operation of the converter is temporarily stopped and the metal is removed.

[0003] Conventional techniques for removing furnace mouth metal include:
There is one disclosed in Japanese Unexamined Patent Publication No. 1-136923. In this technology, a special jig is attached to the lower part of the main blowing lance so that oxygen can be injected into the base metal attached to the furnace mouth. 8 and 9 show the jig attached to the main lance for blowing, FIG. 8 is a longitudinal sectional view, and FIG. 9 is a bottom view. 20 indicates the main lance for blowing. The jig 30 is configured to be attachable to and detachable from the main blowing lance 20, and includes a plurality of spacers 33 arranged radially between a disk 31 and an annular body 32. The jig 30 is attached by a hook bolt 35 inserted into an oxygen jet hole 34 of the main lance 20 for blowing. 36 is a nut, and a white arrow indicates the flow direction of oxygen.

In the blowing main lance 20 to which the jig 30 as described above is attached, the oxygen ejected downward from the oxygen ejection hole 34 collides with the disk 31 and crosses the flow direction. direction, and is ejected radially from the gap between the disc 31 and the annular body 32.

[0005] When using the blowing main lance 20 to which the jig 30 as described above is attached to remove the base metal adhering to the converter mouth, the lance 20 is inserted to a predetermined position in the furnace mouth. , inject oxygen to begin melting the metal. The lance 20 is pulled up in stages to sequentially melt and remove the metal in each predetermined range.

[0006]

Problems to be Solved by the Invention When cutting bare metal with oxygen gas, it is desirable that the oxygen gas be injected at a high flow rate.

However, in the above-mentioned prior art, the oxygen injection flow rate is low and it takes a long time to dissolve the deposited metal.

That is, the oxygen injection hole 3 of the main blowing lance 20
The oxygen supplied from 4 is injected from a nozzle hole-shaped space surrounded by a disk 31, an annular body 32, and a spacer 33. Since the number of hook bolts 34 is small, (the number of hook bolts 35 to be inserted)
), the oxygen injection flow rate cannot exceed a certain flow rate.

Furthermore, even if an attempt is made to narrow the nozzle hole-shaped space by increasing the number of spacers 33 attached, the position of the spacers 33 with respect to the oxygen ejection hole 34 of the main lance for blowing will be random. This causes turbulence in the oxygen jet, and the flow rate of oxygen injected from each nozzle hole-shaped space differs, so that oxygen is injected uniformly over the entire circumference of the converter mouth. It is not possible.

[0010] For this reason, it takes a long time to melt and remove the base metal adhering to the furnace mouth, or excessive oxygen is injected into specific parts of the furnace mouth, damaging the refractories and iron sheathing. Conditions may also occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lance for removing metal that can efficiently melt metal that adheres to the mouth of a converter in a short period of time.

0012

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a plurality of nozzle holes for injecting oxygen are provided radially from the inside to the outside in the lower part, and the nozzle holes The slope is downward from the inside to the outside in a range of 0° to 30°.

The shape of the nozzle hole is preferably a Laval nozzle. It is also desirable that the outer surface be chrome plated.

[0014]

[Operation] Since the lance of the present invention is used exclusively for removing metal, a dedicated nozzle hole is provided at its lower part for injecting oxygen for melting metal. The number of nozzle holes arranged and the inner diameter thereof can be appropriately selected, and oxygen can be injected uniformly over the entire circumference of the converter mouth.

[0015] The nozzle hole is required to be at least horizontal, and usually needs to be sloped downward toward the outside (in the direction of oxygen injection). This is because when melting the ingot adhered to the upper end of the converter mouth, oxygen cannot be injected into the adhered ingot unless the nozzle hole is at least horizontal.

[0016] Furthermore, when the nozzle hole is formed downward, oxygen is injected to the deposited metal from an upper oblique direction. Therefore, even if oxygen is injected from the same position, a wide range of metal can be melted by obliquely scraping it off, and the time required to remove the metal can be shortened. In order to melt the base metal by scraping it off, the slope of the nozzle hole (
angle) must be within an appropriate range, and the slope of the nozzle hole is preferably within a range of no more than 30°. If a lance with a nozzle hole slope of more than 30° is used to melt bare metal, oxygen will be injected into the refractory from which the bare metal has already been removed, damaging the refractory.

Since it is desirable that the oxygen injection flow velocity be in the supersonic range, the shape of the nozzle hole is preferably a Laval nozzle (medium-sized nozzle).

Furthermore, even during the base metal removal operation, splash of molten base metal adheres to the base metal removal lance, but this adhesion can be prevented by applying chrome plating to the outer surface. .

[0019]

[Embodiment] FIGS. 1 and 2 show the lower part of an embodiment according to the present invention, FIG. 1 is a schematic sectional view, and FIG. 2 is an I-I in FIG.
It is an arrow view. In FIGS. 1 and 2, a metal melting lance 1 includes an outer cylinder 2, a middle cylinder 3, and an inner cylinder 4, and has a water-cooled structure with a bottom. 5 is an oxygen flow path, 6 is a cooling water inlet flow path, and 7 is a cooling water outlet flow path. Further, in the lower part thereof, a large number of nozzle holes 8 are provided to penetrate the outer cylinder 2, middle cylinder 3, and inner cylinder 4 and inject oxygen. This nozzle hole 8
are arranged radially from the inside to the outside. Therefore, the entire lance 1 including the nozzle hole 8 is water-cooled.

The nozzle hole 8 is provided at least horizontally, and its slope (angle) is normally inclined downward from the inside of the lance to the outside (oxygen injection direction). The angle θ is set within a range not exceeding 30°.

Oxygen for melting the metal is preferably injected at a high flow rate, and the preferred oxygen injection flow rate is about 400 m/sec to 500 m/sec at the exit of the nozzle hole 8. In this way, since oxygen injection is performed at a flow velocity in the supersonic region, the shape of the nozzle hole 8 is preferably a Laval nozzle. Therefore, the diameter of the nozzle hole 8 is determined so that the oxygen injection flow rate falls within the above range.

The number of nozzle holes 8 to be arranged varies depending on the size of the lance 1, the diameter of the nozzle holes 8, the scale of the converter, etc. However, in general, the spread angle of the gas flow injected from the Laval nozzle is 10° to 13° on one side (2 degrees on both sides).
0° to 26°), the number of nozzle holes 8 needs to be about 14 to 18 in order to spray the injected gas flow seamlessly all around the furnace mouth (360°).

Although not shown, it is desirable that the outer surface of the outer cylinder 2 be chrome plated. When chrome plating is applied, a dense chrome oxide layer is formed on the surface to protect the lance. Furthermore, as mentioned above, molten metal is scattered during the metal removal operation, but since chrome has a high heat transfer coefficient, the scattered materials solidify instantaneously, causing the lance 1 to It will not fuse.

In the figure, the shape of the nozzle hole 8 is shown as a Laval nozzle, but the shape is not limited to the Laval nozzle, and if the oxygen injection is not at a high flow rate exceeding the speed of sound, it can be a normal nozzle. A straight nozzle is sufficient.

The melting operation of the furnace mouth ingot using the ingot melting and removal lance of the above embodiment is carried out as follows. Insert the metal melting lance to a position where oxygen can be sprayed to the lower end of the adhered metal (taking into consideration the inclination angle of the nozzle hole), and start dissolving the adhered metal by spraying oxygen. Then, the lance is pulled up in stages to sequentially melt and remove the metal in each predetermined range.

As mentioned above, the lance of the present invention is a lance exclusively for removing deposited metal, and the method of using it will be explained. FIG. 3 is an explanatory diagram of the preparation status of the metal removal lance during blowing, and FIG. 4 is an explanatory diagram of the status of ingot melting. 3 and 4, 1 is a lance for metal removal, 20 is a main lance for blowing, 40 is a traversing truck, 41 is a lifting truck, 4
2 is a guide for the lifting cart, and 43 is a lance hoist. Further, 21 is a converter, 22 is an attached metal, and 23 is a molten steel.

As shown in FIG. 3, the metal melting lance 1 is always set at the preliminary suspension point of the traversing cart 40, and the amount of metal 22 adhering to the furnace mouth increases and it becomes necessary to remove it. If this occurs, be ready to immediately carry out removal work.

[0028] After the blowing is completed, the main lance for blowing 20 is
is pulled up, the metal melting lance 1 is inserted to a predetermined position, and oxygen is injected to start melting the metal 22.

In addition, in FIGS. 3 and 4, one traverse truck 40 is equipped with a metal melting lance 1 and a blowing main lance 20.
Although the explanation has been given on the case where the metal melting lance 1 is attached, the attachment for using the bullion melting lance 1 may be done on another traversing trolley.

Next, a description will be given of the results of removing ingots adhering to the mouth of a converter with a refining capacity of 250 T/heat using the ingot melting lance shown in FIGS. 1 and 2.

(Example 1) The configuration of the nozzle is as follows, and the insertion position of the lance (distance from the upper end of the converter mouth to the nozzle hole) and the oxygen supply amount (oxygen feeding amount) are The conditions were as shown in FIG. 5, and about 40 T of attached metal was melted and removed. Further, the back pressure in the nozzle hole was adjusted to about 4 kg/cm2 to 7 kg/cm2.

Nozzle configuration Nozzle hole shape Laval nozzle Number of nozzle holes
Throat inner diameter of 16 nozzle holes 1
5mm nozzle hole angle θ
5°

FIG. 5 is a diagram showing the implementation conditions and the completion time of the metal melting, and as shown in this diagram, the time required for the metal melting was only 7 minutes. Furthermore,
The adhered metal was melted uniformly over the entire surface.

(Example 2) The configuration of the nozzle was as follows, and the conditions for the insertion position of the lance and the amount of oxygen supplied were as shown in Figure 6, and approximately 40T of adhered metal was melted and removed. did. Further, the back pressure in the nozzle hole was adjusted to about 4 kg/cm2 to 7 kg/cm2.

[0035] Nozzle configuration: Shape of nozzle hole
Laval nozzle Number of nozzle holes and nozzle hole angle θ 6 nozzle holes of 10° and 6 nozzle holes of 25° arranged alternately Nozzle hole throat inner diameter
14.5mm

FIG. 6 is a diagram showing the implementation conditions and the completion time of the metal melting. As shown in this diagram, the metal melting was completed in 10 minutes. The deposited metal was dissolved uniformly over the entire surface.

(Conventional example) Using a lance fitted with the jig shown in FIGS. 8 and 9, the conditions for inserting the lance and the amount of oxygen supplied are as shown in FIG. was dissolved and removed. As a result, as shown in FIG. 7, it took 15 minutes to dissolve and remove the adhered metal, and Example 1
Approximately twice as much time was required as compared to the case of . In addition, damage to the bricks was observed in a part of the furnace mouth.

[0038]

[Effects of the Invention] In the present invention, a plurality of nozzle holes for injecting oxygen are provided radially in the lower part of the nozzle.
Oxygen can be injected uniformly over the entire circumference of the converter mouth. In addition, since the slope of this nozzle hole is downward from 0° to 30°, it is possible to melt a wide range of base metal by scraping it off obliquely from above, which significantly shortens the time required to remove the base metal. , damage to refractories is avoided.

Furthermore, when the shape of the nozzle hole is a Laval nozzle, the oxygen injection flow velocity can be set in a supersonic range suitable for cutting the bare metal, and the time required for removing the bare metal can be further shortened.

Furthermore, when the surface of the lance is plated with chrome, fusion of molten and scattered metal does not occur, and the life of the lance is extended.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the lower part of an embodiment according to the present invention.

FIG. 2 is a view taken along the line II in FIG. 1;

FIG. 3 is an explanatory diagram showing the preparation state of the bullion melting lance during blowing.

FIG. 4 is an explanatory diagram showing a state in which metal is melted by the metal melting lance of the present invention after blowing is completed.

FIG. 5 is a diagram showing implementation conditions and metal melting completion time in Example 1.

FIG. 6 is a diagram showing implementation conditions and metal melting completion time in Example 2.

FIG. 7 is a diagram showing implementation conditions and metal melting completion time in a conventional example.

FIG. 8 is a longitudinal sectional view showing a state in which a jig is attached to the main lance for blowing.

FIG. 9 is a bottom view of FIG. 8;

[Explanation of symbols]

1　Lance for metal removal 5 Oxygen flow path 8 Nozzle hole 21 Converter 22 Bullion attached to the furnace mouth

Claims (3)

[Claims] Claim 1: A plurality of nozzle holes for injecting oxygen are provided in the lower part radially from the inside to the outside, and the slope of the nozzle holes is 0° downward from the inside to the outside.
A lance for removing metal adhered to the mouth of the converter within a range of 30 degrees from 2. The lance for removing metal deposited at the mouth of a converter according to claim 1, wherein the nozzle hole has a Laval nozzle shape. [Claim 3]Claim 1 in which the outer surface is chrome plated.
Or the lance for removing metal deposited at the mouth of a converter according to claim 2.