JPS63266016A - Nozzle for blowing gas - Google Patents

Abstract

PURPOSE:To obtain a nozzle for blowing gas forming stable and suitable mushroom by constituting the nozzle by collecting many small diameter metal pipes and specifying relation between an interval of the metal pipes side by side and an inner diameter thereof. CONSTITUTION:The small diameter metal pipes 1 are collected by >=20 pieces in a non-porous refractory 2 and connected with a gas introducing pipe 5 through a gas equalizing space 6, and thus the nozzle for blowing gas arranging furnace bottom, etc., of a molten metal refining furnace, is obtd. The above nozzle is constituted, so that the relation between the interval (l) of the small diameter metal pipes 1 side by side and the inner diameter (r) thereof satisfies the inequality: l<=4r<9/4> [mm: unit of (r), (l)]. Further the nearest distance between the small diameter metal pipe 1 and the outer circle of the non-porous refractory 2 is to be >=45mm, desirably >=55mm. By this method, even if at the time of blowing only a little quantity of gas, the stable mushroom is formed and erosion of the nozzle caused by the molten steel and clogging of the nozzle caused by the slag are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of a gas blowing nozzle provided at the bottom of a molten metal smelting furnace.

(Prior Art) Conventionally, a gas blowing nozzle in which a large number of small diameter metal tubes are arranged in a non-porous refractory is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-16771.
6 or Japanese Patent Application Laid-open No. 59-31814, non-porous refractories have an inner diameter of 0.
．． A large number of small diameter metal tubes of 11mm to 4.0IIIm are buried.

In recent years, with the above type of nozzle, the inner diameter of the small diameter metal pipe used has been reduced with the goal of lowering the critical flow rate at which molten metal enters the small diameter metal pipe, and during low flow operation, the molten metal is operated at the critical flow rate of the molten metal into the small diameter metal pipe. Often.

On the other hand, when installing a plurality of metal pipes for stirring molten steel as in Publication of Utility Model Publication No. 60-2177, tuyeres with an inner diameter of 0.5 to 6 maφ are used, and the distance between adjacent pipes is determined by It has been proposed that the diameter be 11 times or less the inner diameter of the mouth. However, this technique is aimed at improving the stirring power by bottom blowing gas, and is not intended to facilitate shaping of the pine mushroom and suppress tuyere melting, which is the aim of the present invention.

Further, Japanese Patent Application Laid-Open No. 61-207505 discloses a technique in which the gas injection through holes of the bottom blowing nozzle of a top-bottom blowing converter are arranged so that they are all located at the vertices of an equilateral triangle.

However, although this technique describes the arrangement of nozzles, it does not describe at all how to space the through holes to optimize the shape of the pine mushroom.

(Problems to be Solved by the Invention) As shown in Fig. 3, the smaller the inner diameter of the small diameter metal tube, the smaller the diameter of the solidified metal (hereinafter referred to as pine mushroom) formed on the surface of the small diameter metal tube. As shown in FIG. 4, the pine mushrooms formed in adjacent small diameter metal tubes 1 are connected and grow into a large pine mushroom 3Δ that covers the entire surface of the nozzle where the small diameter metal tube 1 is buried. becomes extremely difficult. 4 in the figure is a pore.

Therefore, if the nozzle has a structure in which the small diameter metal tubes 1 are dispersed throughout the nozzle as shown in FIG. 5, when a low flow h1 is blown, minute amounts of mushrooms will be formed on the surface of each small diameter metal tube 1 as shown in FIG. 6. Only 3B is formed, and a pine mushroom that covers the entire nozzle cannot be formed. As a result, the nozzle erodes at a high rate, and the slag gets stuck in the nozzle. There were problems such as the bottom blowing effect not being achieved.

(Means for Solving the Problems) The present invention has been made to solve the problems of the prior art, and therefore a low flow rate gas blowing operation is carried out using a nozzle in which small diameter metal tubes are assembled. Even when this happens, a stable pine mushroom is formed that covers the entire nozzle surface of the refractory material in which the small-diameter metal pipe is buried.

That is, the gist of the present invention is that in a nozzle in which 20 or more small diameter metal tubes are assembled, the arrangement interval is set so that the distance Q between adjacent small diameter metal tubes and the small diameter metal tube are the same. Furthermore, in addition to this, the shortest distance between the small diameter metal tube and the outer periphery of the non-porous refractory is set to 45ffiI11 or more, preferably 55III+ or more.

The present invention will be described in detail below based on the drawings.

FIGS. 1A and 1B illustrate a longitudinal section and a plan view (operating surface) of the nozzle of the present invention. In the figure, I is a small metal pipe, 2 is a non-porous refractory, 5 is a gas introduction pipe, 6 is a gas pressure equalization chamber, and the small diameter metal pipe 1 is installed in the center of the nozzle. The metal tube has an inner diameter of 0.1 to 3.0 mm and a wall thickness of 0.2 to 3.01 mm. It is preferable that the wall thickness of the small diameter metal tube is as thick as possible. This is because the metal surface, which is the base point for the growth of pine mushrooms, expands, making it possible for larger pine mushrooms to grow.

In the present invention, the interval between adjacent small-diameter metal tubes l is determined for the following reasons.

As shown in Fig. 8, the radius R (mn+) of the pine mushroom formed at the tip of the small diameter metal tube and the inner diameter r (II
llI+), gas flow m F(Q
/1 inch), there is the following relationship based on the results of heat transfer calculations.

Rdr (2) Regarding the critical flow mF' of molten metal intrusion into a small diameter metal pipe, the relationship shown in the following equation can be obtained from the balance between the static pressure of the molten metal and the buoyancy of the gas.

By combining (1), (2), and (3), the radius of the pine mushroom formed at the limit flow rate of molten metal penetration can be found, and it is expressed by the following formula: R=Ar (A is a constant)... (4) Constant Δ was determined by collecting the lining used in the actual operation and measuring the radius of the formed pine mushroom, and obtained A=2.0.

Furthermore, in order for the pine mushrooms formed on adjacent small-diameter metal tubes to connect, e≦2R (5) should be satisfied (4), as is clear from Fig. 8. Combining formula and formula (5), a≦
Therefore, if gas is blown using the above-mentioned nozzle, even when a small amount of gas is blown, the pine mushrooms generated in each metal tube can be interconnected to form a pine mushroom that covers the entire small-diameter metal tube arrangement section.

In the present invention, it is desirable that the shortest distance α between the small diameter metal tube I and the outer periphery of the non-porous refractory 2 is 45 mm or more.

That is, by doing so, it is possible to reduce the possibility that the brick joints (outer periphery of the siding) will be melted in advance due to back attack caused by gas blown from the bottom of the furnace. When the amount of gas blown from the bottom of the furnace becomes large, such as 50ONn+'/It or more, it is desirable to set α to 55 mm or more, considering that the back attack caused by the gas becomes significant.

(Example) As shown in Figure 2 (a) and (b), the inner diameter is 2 mm and the wall thickness is 1 mm.
116 am small diameter metal tubes 1 at intervals of 12a+m, α
When using a nozzle embedded in a non-porous refractory with a diameter of 54 mm, the gas injection amount is 70 to 600 Nn+'/hr (
A range of original pressure of 10 Kg/cm'') was possible, and even when a small amount of gas (7 ONm'/hr) was blown, it was possible to stably form a pine mushroom covering the small-diameter metal tube arrangement part.

Therefore, the erosion rate of the nozzle is Q, l 9 is/ah
Met.

On the other hand, in a comparative example (when using the nozzle shown in Figure 7 (a), port C) where the spacing was 24 am, α was 231II11, and the wall thickness and number were the same, the nozzle erosion rate was 0.5 mm/
It was ch.

Furthermore, since a stable pine mushroom is formed when using the nozzle of the present invention, the problem of embedding of slag due to the slag that occurs when using an inert gas can be solved, and the nozzle can be stably operated more than 2,000 times.

(Effects of the Invention) As described above, according to the nozzle of the present invention, a stable pine mushroom is formed even when a small amount of gas is blown, so that erosion of the nozzle due to molten metal can be extremely suppressed.
In addition, embedding of the nozzle due to slag can be prevented.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are cross-sectional views and plan views illustrating small-diameter metal tubes according to the present invention, and Figures 2 (a) and (b) illustrate examples of arrangement of small-diameter metal tubes according to the present invention. Plan view and enlarged view, Figure 3 is a diagram showing the relationship between the inner diameter of a small metal pipe and the radius of a pine mushroom formed in the molten steel penetration limit area, Figure 4 is a diagram illustrating the state of formation of a large pine mushroom, and Figure 5 is a nozzle. FIG. 6 is a plan view showing an example of arrangement; FIG. 6 is a view illustrating the state of formation of minute mushrooms; FIGS. FIG. 2 is a diagram illustrating the present invention in detail. 1... Small diameter metal tube 2... Non-porous refractories 3A, 3B... Pine mushroom 4... Pore 5... Gas introduction pipe 6...・Gas pressure equalization chamber Fig. 1 (A), / Z Fig. 3 Small A tatami mat 4 Aη "dq strange 2° Fig. 4 Fig. 5 Fig. 6 R Fig. 7 (A) (mouth J Fig. 8

Claims (2)

[Claims] (1) In a nozzle in which 20 or more small-diameter metal tubes are assembled, the relationship between the interval l between adjacent small-diameter metal tubes and the inner diameter r of the small-diameter metal tubes must be arranged so that the following formula is satisfied. A gas blowing nozzle characterized by l≦4r^θ^/^4 (r and l are in mm). (2) The gas blowing nozzle according to claim 1, wherein the shortest distance between the small diameter metal tube and the outer periphery of the non-porous refractory is 45 mm or more, preferably 55 mm or more.