KR20000025495A - Complex blown-converter disposed with bottom-blown nozzle to have good stirring power - Google Patents

Abstract

PURPOSE: A method for disposing of a bottom-blown nozzle of a complex blown-converter is provided to raise the stirring power by lowering the reduction of the efficiency of the kneading of a molten iron in an ingot steel caused by the clogging of a nozzle. CONSTITUTION: The bottom-blown nozzles(3,4,5,6,7,8) of the complex blown-converter(1)are positioned with the following steps. A 400 mm interval in both inner side and outer side of the nozzle is put toward the center thereof, while four ones of the nozzles are disposed in the same circumference corresponded to 0.41 times for inner size of the converter. Two ones thereof concerning an apex are disposed then therein in the diagonal direction of a parallelogram. Finally, six bottom-blown nozzles are disposed in the parallelogram state on the bottom of 150 tons or less of a low volume complex blown-converter. Thereby, it is possible to improve the stirring power in the converter to reduce total iron contents of the final sum of oxygen and slag, so as to induce the reduction of the amounts of the antioxidizing agent used therein and the improvements of the occurrence of the defectives in the ingot steel, whereby the reduction of the amounts of the deoxygenates results in the prevention from the contamination of the ingot steel.

Description

Composite blower with low odor nozzle arranged to have excellent stirring power

The present invention relates to a method of arranging a low-nozzle nozzle for stirring molten steel in a furnace at the bottom of a composite blower for refining molten iron with molten steel. More specifically, the present invention relates to a lance from the top in a converter operation mainly using molten iron and scrap metal. In the multiple blower furnace, which supplies oxygen gas into the molten steel through the furnace and inert gas is blown from the bottom through a single tube low odor nozzle, six low odor nozzles are installed in the shape of parallelogram to improve the uniform mixing time and efficiency of the molten steel in the furnace. The present invention relates to a method for arranging a low odor nozzle of a composite blower which has an excellent agitation force, which can be improved.

In general, in the converter operation, the main raw materials such as molten iron and scrap metal are charged into the converter, and the oxygen gas is blown at high speed through a lance to oxidize and remove impurities such as carbon, silicon, manganese, phosphorus, sulfur, and titanium. Slag is made by adding subsidiary materials such as quicklime, formation, dolomite, and sintered ore during the removal.

This converter has a top converter that blows only oxygen gas through the upper lance and a low blower that blows oxygen together with nozzle cooling gas at the bottom of the converter, and oxygen is blown through the lance at the top and at the bottom of the converter. There is a complex blown converter that blows an inert gas to improve blow efficiency.

Among the types of converters described above, the combined blower converter combines the excellent slag control ability of the upper converter and the excellent stirring power of the low converter to promote the reaction between the slag and the metal and the decarburization speed is excellent due to the excellent stirring force. Excellent decarburization rate in the area, suitable for low carbon steel production.

In addition, since the oxygen concentration in the molten steel at the same converter end carbon concentration is low, and the content of iron powder in the slag is also low, most of the recent converters have adopted the composite blow method.

The composite blower converter has a single tube nozzle and a multi-pipe assembly nozzle according to the structure of the low odor nozzle, and a single tube nozzle is mostly used in a small converter.

By the way, in the low-capacity composite blower of 150 tons or less using a single pipe nozzle, four low odor nozzles have been generally used as shown in FIG. 1, but the nozzle clogging occurs frequently due to the characteristics of the single pipe nozzle. The remaining nozzle which does not occur excessively is pressured so that local melt loss occurs in the floor refractory around the nozzle, and the overall flow rate of inert gas should be lowered. Increasing the oxygen concentration and increasing the amount of iron in the slag is acting as a factor of the cost increase.

The present invention has been made to solve the above problems, it is characterized in that the six low-nozzle nozzles arranged in a parallelogram shape to reduce the reduction in the blowing efficiency caused by the nozzle clogging phenomenon and improve the overall stirring force. It is an object of the present invention to provide a method for arranging a low odor nozzle, which has a good stirring power.

1 is a layout view of a conventional smelting furnace low odor nozzle,

2 is a layout view of the composite blowing converter low odor nozzle according to the present invention,

3 is a graph showing a relationship between a low odor gas flow rate and a uniform mixing time of molten steel in a furnace according to a conventional method and the present invention;

4 is a graph showing the relationship between the amount of end point oxygen and the amount of end point carbon according to the conventional method and the present invention;

Fig. 5 is a graph showing the relationship between the amount of train content in the endpoint slag and the endpoint carbon amount according to the conventional method and the present invention.

<Description of the code used in the main part of the drawing>

1: converter, 2: conventional low odor nozzle,

3, 4, 5, 6, 7, 8: Low odor nozzles arranged by the present invention

In order to achieve the above object, the present invention is to arrange the six low-nozzle nozzles in a parallelogram shape at the bottom of the low-capacity composite blower converter of 150 tons or less, but three each on each side so as to be perpendicular to the charging side and the outgoing side of the converter. It provides a composite blower converter having a low odor nozzle is arranged to have an excellent stirring power, characterized in that installed at intervals.

In addition, four low odor nozzles are positioned on the same circumference corresponding to 0.39 to 0.43 times the converter inner diameter, and the other two low odor nozzles corresponding to the diagonal vertices of the parallelogram are 0.44 to 0.47 times the converter inner diameter. It is characterized in that the installation on the same circumference corresponding to.

Hereinafter, the present invention will be described in more detail.

First, in the present invention, the reason for installing six low-nozzle nozzles, which are usually installed in even numbers for stirring the molten steel in the furnace, is less than six. This is because the efficiency is rather reduced due to interference between the nozzles and the like.

As shown in Fig. 2, the low-nozzle nozzles 3, 4, 5, 6, 7, and 8 are not interrupted by the charging hole and the exit port, and thus the low-nozzle nozzles 3, 4, 5, 6, 7, 8 ) Were installed on both sides of the converter in the vertical direction with respect to the charging side and the tapping side, and the distance between each nozzle (3, 4, 5) (6, 7, 8) was kept equal for uniform stirring.

In addition, in order to improve the stirring force, that is, to rotate the furnace molten steel more effectively, the overall shape of the nozzle was arranged in the shape of a parallelogram, and for that reason, among the six low-nozzle nozzles (3, 4, 5, 6, 7, 8). Four low-nozzle nozzles (4, 5, 6, 7) are installed on the same circumference corresponding to the furnace diameter 0.39 to 0.43 times, and the remaining two low-nozzle nozzles (3, 8) corresponding to the diagonal vertices of the parallelogram are It was placed on the same circumference corresponding to the furnace inner diameter 0.44-0.47 times.

On the other hand, the reason why the installation range of the low odor nozzles (3, 4, 5, 6, 7, 8) installed as above is limited to 0.39 to 0.43 times and 0.44 to 0.47 times the furnace inner diameter, respectively, is that the low odor nozzle is 0.39 If less than 0.43 times, the effect of agitation is reduced under the influence of the gas pressure ejected from the odorous oxygen lance, and if it is installed more than 0.44 to 0.47 times in the furnace, it causes severe melting damage in the converter wall. .

Hereinafter, an Example is given and this invention is demonstrated in detail.

<Example>

First, as shown in Figure 2, the low nozzle installation position of the present invention is such that the three nozzles (3, 4, 5) (6, 7, 8) on each side around the charging side and the outgoing side of the furnace are 400 mm apart. In the meantime, two nozzles 4, 5, 6 and 7, that is, four nozzles 4, 5, 6 and 7, were arranged on the same circumference corresponding to 0.41 times the furnace diameter, and the diagonal of the parallelogram Two nozzles 3 and 8 corresponding to the direction vertices were disposed at a position of 0.45 times the furnace inner diameter.

The uniform mixing time was compared by the water model test under the same conditions as above, and the water model test was carried out with an acrylic model converter scaled to 1/8 for 100 ton converter, and water was used instead of molten steel. Nitrogen gas was used.

In addition, 20% KCl solution was injected into the upper surface of the male model converter while the low odor gas was blown to measure the electrical conductivity of the water surface and the bottom of the male model converter. .

As shown in FIG. 3, the conventional homogeneous mixing time is generally shorter as the flow rate of the low odor gas increases, and when the flow rate is 20 Nℓ / min or more, there is no significant difference, but according to the present invention, the homogeneous mixing time is conventional. In addition, shortening and stagnation due to an increase in the low odor gas flow rate did not occur.

This is because the low odor nozzle according to the present invention is arranged in a parallelogram shape and the effect of rotating the low odor gas in the furnace is improved.

After the converter is blown, dissolved oxygen exists in equilibrium with the end point carbon concentration and the dissolved oxygen content at the same end point carbon concentration decreases as the stirring force increases.

Such dissolved oxygen is removed using aluminum or silica sand.

That is, if the dissolved oxygen content in the molten steel is lowered at the end point, the amount of deoxidizer input decreases, thereby reducing the cost.

Dissolved oxygen as described above decreased with increasing the end point carbon content, comparing the end point carbon to the end point oxygen when the conventional low odor nozzle shown in Figure 3 and the low odor nozzle according to the present invention is applied to the actual 100 ton converter As can be seen in the graph, the end point oxygen under the same end point carbon content was reduced by an average of 100 ppm or more in comparison with the conventional method by the low odor nozzle of the present invention, thereby significantly reducing the deoxidizer.

This result is also because the low odor nozzle of the present invention is arranged in a parallelogram shape to enable more effective and uniform stirring of molten steel.

On the other hand, Figure 4 compares the conventional low odor nozzle and the low odor nozzle according to the present invention in comparison with the iron content in the final carbon to slag when applied to a 100 ton converter.

The iron content in slag is closely related to the yield of molten steel. The lower the content, the higher the real rate, and the higher the end carbon concentration, the lower the iron content in the slag.

Referring to Figure 4 on the premise that the iron powder in the slag, but both the conventional method and the present invention showed a tendency to decrease as the content of the end point carbon increases, it can be seen that the case of the present invention is on average 0.7% lower than the conventional method Can be.

Due to the arrangement of the low odor nozzle according to the present invention as described above, by improving the stirring power in the furnace, it is possible to reduce the amount of iron in the terminal oxygen and slag to improve the deoxidizer and the yield of molten steel, and the reduction of the deoxidizer in the molten steel The generation of deoxidation products can be reduced to reduce the contamination of molten steel by the deoxidation layer.

Claims (2)

Six low-nozzle nozzles (3, 4, 5, 6, 7, 8) are arranged in parallelogram shape at the bottom of the low-capacity composite blow converter (1) of 150 tons or less, and the charging side and the tapping side of the converter (1) A composite blower for which a low odor nozzle is disposed to have an excellent stirring force, characterized in that three pieces are installed at equal intervals on each side so as to be vertical. The method of claim 1, Four lower odor nozzles (4, 5, 6, 7) of the lower odor nozzles (3, 4, 5, 6, 7, 8) are positioned on the same circumference corresponding to 0.39 to 0.43 times the converter inner diameter, and have a parallelogram shape. The remaining two low odor nozzles (3, 8) corresponding to the vertices of the diagonal direction are installed on the same circumference corresponding to 0.44 to 0.47 times the converter inner diameter. Lotus line.