JPH0813018A - Oxygen lance nozzle for converter blowing - Google Patents

Abstract

PURPOSE:To improve the oxygen efficiency and extend the thermal tolerance of a converter by arranging an oxygen spouting hole of stripe shape having a specified ratio of length to width or of a curved shape. CONSTITUTION:One or more oxygen spouting holes 2 are arranged at the tip end part of a lance nozzle body 1. The oxygen spouting hole 2 is made into a stripe shape having ratio of >=5 of the length to the width or into a curved state. Or, the curved stripe shaped spouting hole 2 is arranged around the circular spouting hole 2. The oxygen jet spouted from the stripe shaped oxygen spouting hole has large attenuation of the jetting speed. Therefore, the low speed of the oxygen jetting can be obtd. on the molten steel surface. Thus, the gas flow rate can be changed during gas-spouting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lance nozzle for blowing molten steel in a converter.

[0002]

2. Description of the Related Art It is well known that if the jet velocity of the top-blown oxygen on the surface of the molten steel increases, the iron yield loss due to spitting increases, and if the jet velocity decreases, the amount of spitting decreases. Is. On the other hand, in converter blowing, the role of top-blown oxygen is to supply molten steel with oxygen,
There was slag agitation, but with the recent technological development to provide bottom-blown agitation force and the spread of hot metal pretreatment, it is possible to increase the jet flow velocity of top-blown oxygen on the surface of molten steel to perform strong agitation of molten steel and slag. Is not necessarily the necessary situation.

Therefore, as described in, for example, Japanese Patent Application Laid-Open No. 57-92123 and Japanese Utility Model Laid-Open No. 1-142441, the oxygen jet flow velocity on the molten steel surface for the purpose of reducing spitting in a converter. In order to reduce the height, measures have been taken to make the oxygen ejection holes of the blowing lance nozzle porous or increase the height of the oxygen blowing lance nozzle. Thus, when refining molten steel by oxygen jet in the converter, the reaching gas jet flow velocity on the molten steel surface is an important factor.To control this gas jet flow velocity, back pressure, gas At least one of the flow rate and the distance from the nozzle tip to the target must be controlled.

Further, it is difficult to control the back pressure and the gas flow rate during the blowing because the Laval nozzle is used.
The distance from the tip of the oxygen nozzle to the surface of the molten steel, which is the target, is forced to be selected with a narrow degree of freedom due to the adhesion of metal to the nozzle and the melting damage of the converter refractory due to gas impact. Therefore, the oxygen jet velocity must be selected within a narrow range during blowing.

[0005]

However, with respect to making the oxygen ejection holes of the blowing lance nozzle porous, there is a drawback that the structure of the lance nozzle becomes complicated due to the porosity and there is a risk of insufficient cooling in the lance nozzle. Have
Regarding the rise of the height of the oxygen blowing lance nozzle, increasing the height of the lance nozzle increases the spread of the oxygen jet, causing collision of the jet with the wall of the converter furnace and causing the unit price of the refractory in the converter furnace to rise. Has the drawback of being worse.

The present invention solves the above-mentioned drawbacks and has a simple structure as compared with a porous lance nozzle, and a low oxygen flow rate can be obtained in a state where the height of the lance nozzle is relatively low, and a wide area fire point can be secured. It is an object of the present invention to provide a lance nozzle for converter blowing which is capable of achieving high secondary combustion. In addition, the back pressure of the nozzle, the gas flow rate, the distance from the nozzle tip to the target object are constant, and the gas flow velocity can be changed during gas ejection. An object of the present invention is to provide a converter blowing lance nozzle capable of changing a gas flow velocity larger than in the past in combination with a change in a distance to an object.

[0007]

The summary of the present invention for achieving the above-mentioned object is as follows. (1) An oxygen lance nozzle for blowing a converter, characterized in that it has at least one strip-shaped or curved oxygen ejection hole having a length-width ratio of 5 or more at its tip.

(2) A gas ejection nozzle having a movable core, wherein the movable core is rotationally moved to change the shape of the gas ejection hole, and two or more gas jets ejected from the gas ejection hole. An oxygen lance nozzle for blowing a converter, characterized in that the maximum velocity of the gas jet when reaching the target is controlled by merging or conversely.

[0009]

FIG. 1 is a view showing an example of an oxygen ejection surface of an oxygen lance nozzle for converter blowing according to the present invention. FIG. 1 (a),
In (b) and (c), 1 is a lance nozzle body,
Reference numeral 2 is an oxygen ejection hole. As an embodiment, as shown in (a), a strip-shaped oxygen ejection hole 2 is arranged, and as in (b), the ejection hole 2 is formed in an arc shape in order to ensure axial symmetry of the ejection flow.
It is conceivable that the rectangular ejection holes 2 are arranged around the conventional circular ejection hole as in (c).

It is known that the oxygen jet ejected from the strip-shaped oxygen ejecting holes has a larger velocity attenuation than the oxygen jet ejected from the conventional circular jet. Therefore, by using the lance nozzle of the present invention, it is possible to obtain a low oxygen jet flow velocity on the molten steel surface at the same oxygen supply speed and the same lance nozzle height as the conventional lance nozzle. If the ratio of length to width is smaller than 5, the above effect cannot be remarkably obtained.

2 and 3 are views showing examples of the nozzle according to the present invention. First, what is shown in FIG. 2 is a nozzle in which a movable part (core) 13 which can be rotated and moved as shown by an arrow is arranged in the central part of the nozzle body 11, and in FIG. ) 13 and the nozzle body 11 contact each other, the gas ejection holes 12 are cut off, and the gas ejection flows are ejected from the four gas ejection holes 12. FIG. 2B shows a state in which the movable part (core) 13 is rotated to a position where it does not contact the nozzle body 1. At this time, the gas ejection holes become annular, and the gas jets coalesce immediately after being ejected from the nozzle, and the jet velocity increases. At this time, the gas jets coalesce immediately after being jetted because a negative pressure region is formed in the central portion of the nozzle. Further, FIG. 3 shows a core moving mechanism in a lance nozzle having these movable cores. As shown in the figure, the movable portion (core) 23 of the nozzle is rotationally moved by the drive device 24 that allows vertical movement or rotational movement at the upper end of the lance.

[0012]

EFFECTS OF THE INVENTION By using the oxygen lance nozzle for blowing a converter of the present invention to blow oxygen by ejecting oxygen from a strip-shaped oxygen ejection hole, iron yield due to spitting is generated in the converter. It is possible to reduce loss, increase oxygen efficiency by securing a wide-area fire point area, and increase the converter thermal tolerance due to the high secondary combustion rate.

Further, by using the oxygen lance nozzle for converter blowing of the present invention which can change the shape of the gas injection hole and change the jet velocity during blowing, the back pressure of the nozzle, the gas flow rate,
While the distance from the nozzle tip to the target is constant, the gas flow velocity can be changed during gas ejection, and in combination with the back pressure of the nozzle, the gas flow rate, and the change from the nozzle tip to the target, It is possible to change the gas flow velocity more drastically than before.

[Brief description of drawings]

FIG. 1 is a view showing an example of an oxygen ejection surface of an oxygen lance nozzle for converter blowing according to the present invention. 1 Lance nozzle body 2 Oxygen ejection hole

FIG. 2 is a view showing an oxygen lance nozzle for converter blowing having a movable part (core) of the present invention, in which (a) is the movable part (core).
Shows a state of contacting the outer wall of the nozzle, and (b) is a diagram showing a state where the movable part (core) rotates and does not contact the outer wall of the nozzle. 11 Nozzle body 12 Gas jet ejection hole 13 Movable part (core)

FIG. 3 is an explanatory diagram showing an outline of a drive mechanism of a movable part (core) of a lance nozzle. 21 Lance Nozzle Body 22 Oxygen Ejection Hole 23 Movable Part (Core) 24 Movable Part (Core) Drive Device

Claims (2)

[Claims] 1. An oxygen lance nozzle for blowing a converter, wherein the tip has at least one strip-shaped or curved oxygen jet hole having a length-width ratio of 5 or more. 2. A gas ejection nozzle having a movable core, wherein the movable core is rotationally moved to change the shape of the gas ejection hole, and two or more gas jets ejected from the gas ejection hole are formed. An oxygen lance nozzle for blowing a converter, characterized in that the maximum velocity of a gas jet when reaching a target is controlled by combining or vice versa.