KR20130019562A - Tapping spout structure for converter - Google Patents

Abstract

PURPOSE: A molten metal exit structure is provided to suppress the drop of temperature by reducing tapping time and to reduce a reheating process in a subsequent process. CONSTITUTION: A molten metal exit structure includes steel-tapping holes(100,200) ejecting molten steel from a refine converter(10). The molten metal exit structure comprises two steel-tapping holes departed from each other. If a steel-tapping hole caliber of the converter in which a tapping is completed within 3-6 minutes is called A, the steel-tapping holes departed from each other as described above is between 0.5-1.0A. If the steel-tapping holes described above are B, a distance between the two holes is between 1.5-4.0B. The steel-tapping holes described above are formed in either in parallel or vertical to the steel-tapping hole. The distance between the centers of the steel-tapping holes is either 2.0B or 3.0B.

Description

TRACKING SPOUT STRUCTURE FOR CONVERTER}

The present invention relates to a converter outlet structure, and more particularly, to a converter outlet structure capable of delaying slag outflow by delaying the formation of vortices at the exit port during the converter tapping operation and shortening the tapping time.

In general, molten iron that has undergone preliminary molten iron treatment (delining and desulfurization) is charged into the converter and undergoes a converter refining process called oxygen blowing along with the input of main raw materials such as scrap iron and cold wire and quick raw materials such as quicklime, dolomite and iron ore. do. The total time in the converter takes about 35 ~ 60 minutes of refining time, considering the characteristics of each steel mill, including preparation time for operation. After the converter refining process, the secondary steel refining process is carried out by removing molten steel in a container called a water ladle to remove components, temperature, and impurities, and then the molten steel is sent to a continuous casting process. In the charter preliminary treatment, a charter is used to load the molten steel into the converter by tilting the molten iron loading ladles, in the converter, tapping the molten steel with the taps through the tapping hole, and in the second refining process, through the nozzle of the taps. Tap the molten steel in the first process, Tundish.

The converter tapping process taps the molten steel (3) with the tapping ladle (2) through the tapping hole (5) while tilting the converter (1) at a predetermined angle, as shown in FIG. It takes about 6 minutes to attend.

On the other hand, the slag (4) outflow into the tap opening (5) during the tapping of the steelmaking steel from the converter (1) is largely divided into the beginning, middle, and end of tapping, and in the initial stage, the slag enters the inside of the tap along with the turning of the converter. It appears to be mixed first, it is mainly caused by vortex formation in the middle stage, it is known to occur when molten steel and slag come out together because the amount of molten steel is small.

The slag 4 present in the upper part of the molten steel is mixed into the steel ladle 2 through the tap hole 5, and since the oxidizing elements P 2 O 5, FeO, etc. are present in the slag in a large amount, Al is added in the secondary refining process. Most of the steelworks are reduced to molten steel, which adversely affects the components of the molten steel. Therefore, most steel mills are conducting technology development activities to reduce slag spillage at the steelworks.

Representative methods include the use of suspended solids such as slag checkballs in the past 90s to prevent late slag outflow, the introduction of slag dart during tapping to prevent outgoing and late tapping, and the use of gas during tapping. The method of blasting on the steel top surface, the method of bubbling gas from the refractory during the tapping, the tapping control method of the sliding gate method, and the like are known to date, but all of them have their respective limitations and disadvantages. Currently, most steel mills use dart technology most widely.

On the other hand, Japanese Laid-Open Patent Publication No. 1981-105414 discloses a tap structure consisting of three taps (7, 8) to prevent slag outflow (see Fig. 2), the molten steel is tapping through tap 8, Only the slag is discharged through the outlet 7 (see FIG. 3). In such a configuration, a separate storage means for storing the slag discharged under the outlet 7 is required, which complicates the operation equipment. There is a problem that the production cost increases. In addition, the above patent does not control the diameters or intervals of the taps 7 and 8, and there is a problem that slag outflow due to vortex generation cannot be suppressed or delayed.

In addition, in recent years, activities to cope with global warming and energy reduction have continued at steel mills. In the steelmaking process, low HMR (low hot metal ratio) operation and minimization of temperature reduction among processes are relevant. There is a temperature reduction process of about 10 to 40 degrees even in the above-described converter tapping process. This temperature reduction process is also related to the tapping time. Long tapping times reduce the temperature significantly and, if necessary, must be heated again in a subsequent process to rise to an appropriate temperature. In order to shorten the tapping time, simply increasing the tap size may reduce the temperature and the tapping time, but there is a problem that the slag outflow due to the vortex also increases at the same time.

Japanese Patent Laid-Open No. 1981-105414

One technical problem of the present invention is to provide a converter outlet structure capable of delaying slag outflow by delaying vortex formation at the outlet.

In addition, one technical problem of the present invention is to provide a converter tap structure that can shorten the tapping time to prevent temperature reduction due to tapping to improve productivity.

The converter opening structure according to the embodiment of the present invention,

In the converter gate structure having a tap hole for discharging the molten steel from the converter to take and refine the molten steel, it consists of two mutually spaced taps, the exit diameter of the converter is completed in 3 to 6 minutes When A is referred to, the spaced two exit holes are formed in a size of 0.5A to 1.0A, respectively.

In addition, in the converter gate structure having a tap hole for discharging the molten steel from the converter to take and refine the molten steel, it consists of two taps spaced apart from each other, when the average diameter of the two taps are spaced B The distance between the centers of the two exit holes is formed in the size of 1.5B to 4.0B.

In addition, in the converter gate structure having a tap hole for discharging the molten steel from the converter to take and refine the molten steel, it consists of two taps spaced apart from each other, the tapping of the converter is completed in 3 to 6 minutes When the aperture diameter is A, the spaced two exit holes are 0.5A to 1.0A, respectively. When the average diameter of the spaced two exit holes is B, the distance between the centers of the two exit holes is 1.5B. To 4.0B.

The spaced two taps are preferably formed in a direction parallel to the upright direction of the converter or in a direction orthogonal to the upright direction of the converter.

Preferably, the distance between the two centered exit holes is 2.0B to 3.0B.

In addition, the converter may be manufactured to include the converter outlet structure described above.

According to the embodiment of the present invention as described above, it is possible to implement the vortex canceling effect by adjusting the interval, the distribution between the diameter of each of the double taps and the double taps. Accordingly, it is possible to continuously reduce the increase speed of the rotational flow rate that increases toward the exit port to prevent the slag outflow. In addition, the tapping time can be shortened, so that the temperature decrease during tapping can be suppressed. As a result, the reheating process in subsequent processes can be reduced, and energy saving and productivity can be improved in the steelmaking process.

1 is a diagram illustrating a general converter tapping process;
2 and 3 is a view showing a converter outlet according to the prior art,
4 is a view showing a vortex in which the bath surface of the fluid is settled in a funnel shape,
5 is a diagram showing the principle of vortex generation and the relationship between the rotational speed of the fluid and vortex generation;
6 is a view showing the vortex shape generated in a single tap and the vortex canceling effect in a double tap;
Figure 7 is a cross-sectional view showing the converter outlet structure according to an embodiment of the present invention, (b) and (c) is a view facing the double outlet side from the hot water,
8 is a diagram showing a converter used in the water model experiment;
9 is a graph showing the results of a number model experiment;
10 is a graph showing the vortex generation height according to the change in distance between the center of the tap hole;
11 is a graph showing the numerical analysis results of FIGS. 9 and 10.

Some fluid is contained in a certain container, and the fluid discharged through the outlet at the bottom of the container generates an eccentric force due to the rotation of the earth, which rotates counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. Vortex occurs on the upper surface of the fluid, and at the center of the vortex a vortex (see FIG. 4) occurs in which the bath surface of the fluid settles into a funnel. The rotation of the fluid is determined by the above-mentioned eccentric force when the fluid is maintained for a long time or when all external force is removed, but in practice, the fluid is rotated by a complex element. Finding directions is not easy.

The principle of vortex generation can be interpreted by the law of conservation of angular momentum and Bernoulli's equation. When the outlet is opened in a certain vessel, the angular momentum at any point is preserved, which is expressed as in equation (1) below.

Equation (1): L = mr ² _x wx = constant (L: angular momentum, m: mass of fluid particles, r _x : horizontal distance away from the center of the vessel outlet)

Equation (1) may be represented by Equation (2) as follows: (r1 <r2)

Equation (2): L = mr ₁ V = mr ₂ V = constant

That is, as shown in FIG. 5, as the distance decreases from the point r _{2 to the} point r ₁ in the container, the rotational speed V of the fluid increases, so that the rotational speed of the fluid is the fastest at the top (center area) of the outlet.

Applying Bernoulli ’s equation to it gives the following equation (3).

Equation _{(3): P o + d} s gH s + 1 / 2d l V 2 + d l gH l = constant (P o: atmospheric pressure, d _s, d _l: specific gravity of the slag and the molten steel, H _s, H _l: Height of slag and molten steel)

According to Equation (3), when the fluid is discharged, when the rotational speed V increases, the atmospheric pressure and slag height are constant, so the height H ₁ of the molten steel must decrease. Thus, combining Eq. (2) and Eq. (3), when discharging fluid from any vessel, is the fastest point as the rotational speed of the fluid develops at the point above the outlet, so that the center of fluid is funneled. Vortex in the shape will be generated. In order to minimize the slag outflow due to the vortex phenomenon, it is suggested that the inevitable slag outflow phenomenon can be suppressed to the maximum in at least the same process if the initial rotational flow velocity can be reduced.

Accordingly, the present inventors have devised a method for suppressing or delaying vortex formation as much as possible. As a result, the converter outlet structure is configured in the form of a dual tapping in the form of a conventional single tap, and the vortex canceling effect by adjusting the distance and distribution between the respective apertures and the double taps (Fig. 6). It can be implemented. Accordingly, it is possible to continuously reduce the increasing speed of the rotational flow rate that increases toward the exit port to prevent the slag outflow.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that the same components or parts among the drawings denote the same reference numerals whenever possible. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as not to obscure the subject matter of the present invention.

Figure 7 is a cross-sectional view showing a converter outlet structure according to an embodiment of the present invention, (b) and (c) is a view facing the double exit side from the water surface, Figure 8 is a converter used in the water model experiment 9 is a graph showing the results of the water model experiment, FIG. 10 is a graph showing the vortex generation height according to the distance change between the centers of the exit holes, and FIG. 11 is a graph showing the numerical analysis results of FIGS. 9 and 10. to be.

As illustrated in FIG. 7, the converter outlet structure according to an embodiment of the present invention may include a converter outlet structure including a outlet for discharging the molten steel 30 from the converter 10 that receives and refines molten steel. In this case, it has a double tap hole consisting of two taps 100, 200 spaced apart from each other. Here, the two tapping holes 100 and 200 are formed with the apertures D: D1 and D2 and the interval L optimized by the experiment.

The exit aperture can be formed in various ways depending on the operating environment, and the size of the exit aperture can be defined in various ways. For example, it is possible to set the exit diameter compared to the size of the converter, the size of the exit diameter can be set according to the flow rate / flow size. In addition, the tap size may be defined based on the time when tapping of the converter steel is completed. The start time is inversely proportional to the exit size and proportional to the converter size. If the converter size is fixed, the tap time can be defined by the tap size. In addition, when the tap size is fixed, the tap time may be defined as the converter size. Thus, the time at which the tapping is completed may be defined as a function of tap size and converter size. In this embodiment, the tap size is defined using the time at which tapping is completed as a parameter. For example, if the converter has a capacity of 10 tons and the flow rate of molten steel discharged through the tap is 1 ton / min, the tapping time is 10 minutes. For example, when the capacity of the converter (size of the converter) is 3 tons and the flow rate of the molten steel discharged through the tap hole is 0.6 ton / min, the tapping time is 5 minutes. In the embodiment of the present invention, the exit diameter of the converter, in which tapping is completed between 3 to 6 minutes, is defined as A. In other words, when the converter size is 6 tons, the size of the tap size of the tap opening so that the flow rate of molten steel discharged through the tap is 1.0 ton / min to 2.0 ton / min is defined as A.

When defining A in this way, the diameters D: D1 and D2 of the taps 100 and 200 in the form of double taps are preferably 0.5A to 1.0A. Meanwhile, the aperture D1 of the tap hole 100 and the aperture D2 of the tap hole 200 may be formed differently in the range of 0.5A to 1.0A. When the diameter D of the tap holes 100 and 200 is less than 0.5 A, the slag 40 flow rate is greatly reduced, but it does not contribute to the reduction of the tap time. If it exceeds 1A, the tapping time is reduced, but the tapping flow rate is too high, and the slag flows out together in a large amount, and when the slag leak is detected, no further action is taken. In addition, molten steel components need to be adjusted together with the spilled slag, so that a large amount of ferroalloy is added, because when the alloy iron is dissolved in molten steel, the necessary time is insufficient to cause component variation. Of course, in the level of understanding the steelmaking industry, if additional measures are taken, for example, when the bottom bubbling and slag detection devices are sufficiently utilized during operation, the operation is possible even in the above range.

On the other hand, the two tapping holes 100 and 200 spaced apart may be formed in a direction (vertical direction) parallel to the upright direction of the converter, as shown in Figure 7 (b), or as shown in Figure 7 (c) It may be formed in a direction (horizontal direction) perpendicular to the upright direction of the converter. In the case of manual tapping operation, which is not the actual automated operation, the tapping operator needs to check the tapping flow, so it is formed by selecting one of the vertical direction and the horizontal direction so that the flow of the melt at each tap can be seen in the field of view. It is desirable to. Of course, the present invention is not limited thereto and may be formed in an oblique direction in some cases.

Next, the distance L between the centers of each tapping hole 100 and 200 in the form of a double taping hole will be described. Criteria for setting the distance (L) between the center of the exit can be defined in various ways. The exit diameter of the converter, in which the tapping is completed in 3 to 6 minutes, is called A, and the apertures of the two spaced exits 100 and 200 are selected between 0.5A and 1.0A, and this is defined as B. . For example, when the exit diameter D is set to 0.85A, 1B = 0.85A. On the other hand, when the diameter D1 of the tapping hole 100 and the diameter D2 of the tapping hole 200 are formed different from each other, the average value of the tap opening diameters D1 and D2 is set to B. For example, when the tap-hole diameter D1 is 0.75A and the tap-hole diameter D2 is 0.85A, the average value is 0.8A = 1B. When the diameter of the exit holes 100 and 200 is referred to as B, the distance L between the exit centers may be set to 1.5B to 4.0B. If the distance between the exit center is less than 1.5B, the vortex canceling effect was not large, and at 4.0B or higher, the distance between the exit centers is too far away, which may make it difficult to take the water in the receiving ladle 20. This is because the deviation is large in some cases. The distance between the most preferable tapping zone is 2.0B to 3.0B between tapping centers, and the reason thereof will be described later.

On the other hand, even when the tap structure as a double tap as in the embodiment of the present invention can be expected to prevent the slag outflow effect by the dart (dart) device still used in a single tap. Accordingly, the present invention can also design a double tap and a double dart device applied to each tap. In addition, a slag sensing device and a pneumatic stopper may be implemented in each tap. In some cases, the pneumatic stopper operating system may be driven independently from the detection after the dart.

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

In order to confirm the practical applicability, a well-known numerical model experiment was conducted. Using a 1/8 size acrylic bath of 300 ton converter, simulation of molten steel was carried out using water.

As shown in FIG. 8, the diameter of a single tap was formed to be 26 mm in the male model experiment, and the diameter of the double tap was about 85% of the single tap in a direction perpendicular to the upright direction of the converter. 22 mm corresponding to the size was formed. Meanwhile, the distance between the centers of the two exits in the double exit was set to 1.5 to 3.0 times the diameter of the exit.

9 is a graph showing the results of a number model experiment. Referring to Figure 9, the vortex generation height at the single tap (Single) was about 9.0cm, the vortex generation height at the dual tap (Dual) (33mm distance between the center of the tap is about 6.8cm, about 2.2cm) It was confirmed that the time of vortex generation was delayed due to the height difference of, and the time of tapping was reduced by 10 ~ 20%. Since the tap time depends on the tap size, the tap size can be adjusted in the range of 0.5A to 1.0A.

10 is a graph showing the vortex generation height according to the change in distance between the centers of the taps. Referring to FIG. 10, when the distance between the centers of the exit holes is 1.5 times the diameter of the exit hole, the vortex generation height is about 6.8 cm, and when 2.0 times, the vortex generation height is about 6.5 cm, and when 2.5 times, the vortex generation height is At about 6.3 cm and 3.0 times, the vortex generation height was about 5.4 cm. From this, when the distance between the center of the tap hole is 2.0 times to 3.0 times, the vortex generation height is lower than that of other sections, so that the effect of the vortex generation time delay is large, and a uniform vortex generation height without deviation can be obtained.

On the other hand, as shown in Figure 11 and 10 through the numerical analysis, as shown in Figure 11, in the case of a single tap (Single), the linear velocity of the molten steel is about 52cm / s, the distance between the center of the tap Is 2.0 times the double tap hole (Dual_2B), the linear speed of the molten steel is about 29cm / s, the double tap (Dual_4B) with a distance of 4.0 times the center of the tap, the molten steel is about 23cm / s appear. Therefore, as compared with the single tap, it was confirmed that in the case of the double tap, the linear velocity of the molten steel was reduced to about 40 to 50%. This decrease in linear velocity of the molten steel suggests a decrease in the rotational flow rate, thereby suppressing or delaying the generation of vortices causing the slag outflow.

As described above with reference to the drawings illustrating a converter outlet structure according to the present invention, the present invention is not limited by the embodiments and drawings disclosed herein, but to those skilled in the art within the technical scope of the present invention Of course, various modifications can be made.

10: converter 20: course ladle
30: molten steel 40: slag
100, 200: exit door
D: Exit diameter L: Distance between exit centers

Claims (6)

In the converter outlet structure having a tap hole for discharging the molten steel from the converter for taking molten steel to refine;
It consists of two mutually spaced exits,
When the exit diameter of the converter is completed in 3 minutes to 6 minutes, A, the spaced two exit diameters of the converter is 0.5A to 1.0A, respectively.
In the converter outlet structure having a tap hole for discharging the molten steel from the converter for taking molten steel to refine;
It consists of two mutually spaced exits,
When the average diameter of the two outlets spaced apart as B, the distance between the center of the two outlets is 1.5B to 4.0B.
In the converter outlet structure having a tap hole for discharging the molten steel from the converter for taking molten steel to refine;
It consists of two mutually spaced exits,
When the exit diameter of the converter, in which the tapping is completed in 3 to 6 minutes, is A, the spaced two exit diameters are 0.5A to 1.0A, respectively.
When the average diameter of the two outlets spaced apart as B, the distance between the center of the two outlets is 1.5B to 4.0B.
The method according to any one of claims 1 to 3,
The spaced two taps are formed in a direction parallel to the upright direction of the converter or in a direction perpendicular to the upright direction of the converter.
The method according to claim 2 or 3,
A converter gate structure in which the distance between the two centered exit holes is 2.0B to 3.0B.
A converter comprising the converter hatch structure of any one of claims 1 to 3.

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