JPS60251214A - Gas blowing nozzle for melting and refining furnace or reactive vessel - Google Patents

Abstract

PURPOSE:To obtain the titled nozzle less in fluctuation of the quantity of blowing gas and small in wear of base material by inserting plural metallic pipes small in diameter into the nozzle main body consisting of refractory compositions and providing a heat insulating layer to the outer peripheral surface of the nozzle main body. CONSTITUTION:A nozzle main body consisting of a refractory 3 wherein the base material is MgO-C is provided to the upper end of an air accumulator 2 which is provided to the upper end of a gas feeding pipe 1. Plural metallic pipes 4 small in diameter are inserted into the refractory 3 on concentric circles at equal intervals and the lower ends of these pipes 4 are respectively opened to the inside of the air accumulator 2 and the upper ends are opened to the inside of a melting and refining furnace or a reactive vessel at the tip of the nozzle. A heat insulating layer 5 consisting essentially of metallic oxides which have high corrosion resistance for slag and low heat conductivity is provided to the outside peripheral surface of the nozzle in about 0.1-5mm. layer thickness. Thereby, the nozzle having a long life can be obtained and the operation is stably performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a gas injection nozzle for refining, and in particular, the present invention relates to a gas injection nozzle for refining, and in particular, the present invention relates to a refining gas injection nozzle for injecting a reaction gas and/or into a melting and refining furnace or a metallurgical reaction vessel.
Or related to a refining gas injection ± nozzle for blowing an inert gas (background art) Conventionally, a reactive gas and/or an inert gas is injected into a molten metal in a melting and refining furnace or a metallurgical reaction vessel. Refining, degassing, or stirring of molten metal is carried out by blowing directly into the side or bottom of the molten metal container. Conventionally, nozzles such as those described in A and B below are known.

N. A nozzle that is attached to the bottom of a reaction vessel in which molten metal is charged, and is made of a refractory and is surrounded by a plurality of small-diameter metal pipes through which the blown gas passes.

B. A nozzle made of a refractory that is attached to the bottom of a melting and refining furnace such as a converter, and in which MgO-C, which is a highly durable material, is used as the base refractory that constitutes the nozzle.

The above-mentioned nozzle consists of dozens of small-diameter entertainment pipes with an inner diameter of about 0.1 to 5 m encircled in a refractory, and can pass a large amount of gas, as well as blow gas. There is an advantage that the opening of the pipe opening into the furnace will not be blocked by molten metal even if the amount approaches zero.

In addition, in the nozzle B, Mg is a highly durable material.
Since O-c refractory is used as the base material, it has the advantage of being excellent in fire resistance.

The present inventors believe that if Mg0-C, which is a highly durable material used in the nozzle B, is used in a nozzle made of multiple small-diameter metal pipes loaded on the refractory of the previous EA, Considering the advantages of using the A and B nozzles, namely, that the pipe opening will not be blocked by molten metal even if the gas flow rate varies over a wide range, and that a nozzle with excellent fire resistance can be obtained, this idea was developed. A nozzle along the lines was fabricated, installed in a converter, and subjected to practical tests.

However, the prototype nozzle did not achieve the designed bottom-blowing gas flow rate, contrary to expectations, and was unable to fully demonstrate its function as a bottom-blowing nozzle.

(Object and Structure of the Invention) An object of the present invention is to provide a nozzle that eliminates and improves the drawbacks of the conventionally structured nozzle and the nozzle that was subjected to practical tests by the inventors of the present invention. This object can be achieved by providing a gas blowing nozzle according to the claims.

That is, the present invention is a refining gas blowing nozzle,
A refining gas injection nozzle comprising a plurality of small diameter metal pipes stacked in a nozzle body made of a refractory composition, wherein a heat insulating layer is provided on the outer peripheral surface of the refractory constituting the nozzle body. It relates to gas blowing nozzles.

Next, the present invention will be explained in detail.

In order to overcome the above-mentioned drawbacks, the present inventors conducted a detailed study on the situation in which gas is blown from the nozzle during furnace operation. It was observed that the actual amount of gas that could be produced decreased.

As a result of detailed analysis of the phenomenon in which the gas amount decreases and the nozzle capacity decreases, the inventors found that Mgo-C refractories are superior in terms of fire resistance, but compared to conventional nozzle refractories. However, because of its high thermal conductivity, nozzles using Mg0-C refractories experience rapid temperature rise of the refractory over time after the start of use, and the gas flowing inside the pipe is heated and expands, causing the inside of the pipe to expand. We have come to the conclusion that a so-called thermal choke phenomenon occurs, in which the actual amount of gas flowing is reduced.

A table test using a small diameter gold volume pipe confirmed that the actual amount of gas that can flow through the pipe varies depending on the external equipment. The present inventors believe that, in order to prevent the thermal choke phenomenon, it is necessary to suppress heating of the gas injection pipe due to heat transfer from molten steel as much as possible, and to do so, the outer periphery of the nozzle refractory must be This invention was completed based on the new finding that thermal choke phenomenon in gas injection pipes can be significantly prevented by providing a heat insulating layer to prevent heat transfer from molten steel.

The invention will now be explained in detail with reference to the drawings.

Figure 1 is a longitudinal sectional view of the gas blowing nozzle of the present invention, Figure 2'
1m is a plan view taken along the arrow 11-I in FIG.

In the nozzle of the present invention, an air storage chamber 2 that serves as a surge tank for supply gas is configured at the upper end of a gas supply pipe 1. A plurality of small-diameter metal pipes (5) and pipes 4 are stacked inside the pipe 3, and the lower ends of the plurality of small-diameter metal pipes 4 each open into the air storage chamber 2, and the upper ends are the tips of nozzles that can be used inside the furnace or It opens into the container.

A heat insulating layer 5 is provided on the outer peripheral surface of the nozzle.

The heat insulating layer 5 can be made of a material mainly made of metal oxide, which has high corrosion resistance against the slag in the furnace and has low thermal conductivity. In order to coat the outer peripheral surface of the nozzle with the heat insulating material 5, the nozzle is immersed in the oxide in a slurry state, or
Alternatively, applying the oxide in a slurry state to the nozzle,
This can be carried out by a method in which the thickness of the heat insulating coating layer is approximately 0.1 to 5 m. Other metal oxides with low thermal conductivity include alumina, zirconia, and silica, and these can be used alone or as a composite depending on the usage conditions. Water glass can also be used as a binder.

Example What is the furnace frequency and maximum gas flow rate for the nozzle installed in a 180-ton converter in a steel factory? Check the relationship with 'Jm'/mln (
6) Ta. The relationship is shown in FIG. In Fig. 3, the vertical axis shows the gas flow rate, and the horizontal axis shows the number of refining times using the furnace with updated support (hereinafter referred to as the number of furnaces).1~ The state in which the flow rate changes depending on the number of furnaces when a conventional nozzle is used. with a,
The shape was the same as that of a conventional nozzle, but the nozzle was operated by adding resin to a single MgO powder to form a slurry, and then immersing the nozzle, which has an integral pipe structure, in this slurry to form a heat insulating layer. b indicates the state in which the flow rate changes depending on the number of times the furnace is used. According to the figure, the conventional nozzle has a period in which the gas flow rate significantly decreases in the middle range of the number of furnace ports, but the nozzle with the heat insulating layer of the present invention can be operated without causing a drop in gas flow rate in the middle range. It is clear that

c) Effects of the present invention) As described above, in a melting and refining furnace or a reaction vessel equipped with the blow nozzle of the present invention, there is little variation in the amount of gas blown into the reactor, and stable operation is possible. Wear and tear can also be reduced, making it possible to obtain a nozzle with a long life. In addition, since the nozzle of the present invention has small diameter metal pipes arranged concentrically at approximately equal intervals,
The distribution of thermal stress that occurs in the refractory is the same, preventing the occurrence of cracks, reducing the rate of nozzle wear, and almost preventing troubles caused by hole clogging.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the gas injection nozzle of the present invention, FIG. 2 is a plan view taken along the line M-I in FIG. . l...Gas supply pipe, 2...Air storage chamber, 3...Refractory material, 4...Small diameter metal pipe, 5...Insulating layer. Patent applicant Kawasaki Steel Corporation Patent applicant Kawasaki Rozai Co., Ltd. Representative Patent attorney Mura 1) Political patent attorney Takuya Hatano Figure 2 Figure 3 Number of times

Claims (1)

[Claims] / A gas injection nozzle for refining, which comprises a nozzle body made of a refractory composition and a plurality of small diameter metal pipes encircled therein, wherein the refractory gas injection nozzle constituting the nozzle body is A gas injection nozzle for refining that has a heat insulating layer on the outer surface of the object.