KR100605689B1 - Method for measuring naked eye size of molten steel in ladle - Google Patents

Abstract

The present invention relates to a method for measuring the size of the hot water when the molten steel contained in the ladle in the steelmaking process during the steelmaking process by a low odor method, by using the radiant heat radiated from the ladle in which molten steel is taken The aim is to provide a method for measuring molten steel size accurately and more economically.

The present invention is a method for measuring the size of the Natang using the heat radiated from the upper ladle, the difference between the temperature of the solution coming in through the tube and the temperature of the solution going out, using the flow rate of the solution to calculate the radiant heat absorbed by the solution per hour The main point is to measure the size of the molten steel in the ladle using the relation between the radiant heat and the size of the tang.

Ladle, Natang, Low Odor, Stirring, Molten Steel, Radiant Heat

Description

METHOD FOR MEASURING NAKED EYE SIZE OF MOLTEN STEEL IN LADLE}

Figure 1 is a schematic diagram showing the appearance of the rattles when the gas blowing operation

Figure 2 is a schematic diagram for explaining that the gas leaked to the outside in the actual blowing operation

3 is a schematic diagram showing an example of a molten metal measuring device for implementing the present invention;

Figure 4 is a graph showing the correlation between the Natang size measured value and the actual measured value in accordance with the present invention

         Explanation of symbols on main parts of drawing

1 ... ladle 2 ... molten steel 3 ... slag 4 ... Natang

10 Tube 11 Entrance thermometer 12 Exit thermometer

14 ... radiant heat shield 20 ... Thermocouple for molten steel temperature measurement

30 ... thermocouple for slag measurement

The present invention relates to a method for measuring the size of the hot water when stirring the molten steel contained in the ladle in the steelmaking process of the steelmaking process by a low odor method, more specifically, the hot water generated during low stirring of the molten steel contained in the ladle It relates to a method of measuring the size using radiant heat.

In general, in the steelmaking process, more specifically in the secondary refining process, it is a key to the technology to accurately control the composition and temperature of the molten steel.

In order to achieve the above object, the ferroalloy is added or a cooling operation or a temperature raising operation is performed.

The task that must always be accompanied is the uniformity of temperature and components.

As a means of the above-mentioned homogeneous operation, a gas may be blown in from the top using a lance, or a porous nozzle may be installed at the bottom of the ladle and blown through the nozzle.

In general, the latter method (hereinafter referred to as "low odor method") is widely used in consideration of the molten steel component, the temperature uniformity ability, and the degree of improvement of molten steel cleanliness.

At this time, the molten steel must be stirred within the appropriate stirring force range to secure the desired molten steel quality.

The desired stirring force is usually determined by the amount of gas used for stirring, and the purpose is usually achieved by adjusting the flow rate of the gas even when the stirring force is adjusted.

However, in the case of the low odor method, abnormal conditions such as occurrence of leakage phenomenon in the gas delivery pipe and deterioration of nozzle integrity occur frequently, and in this case, the agitation force cannot be exhibited by the gas flow rate.

Therefore, the operator visually observes the upper part of the molten steel 2 received in the ladle 1 as shown in FIG. 1 to determine the agitation degree from the size of the molten steel 4 generated in the upper part of the molten steel.

Reference numeral 3 in FIG. 1 represents slag.

In performing such a process, the information is not automatically acquired, and unnecessary work of lifting and lowering the cover is added for the operator's visual observation, and the work position is shifted and one auxiliary worker is added to secure an easy viewing field. It is accompanied by problems such as necessity.

The present inventors have conducted research and experiments to improve the above-mentioned problems of the prior art, and based on the results, the present invention has been proposed, and the present invention is more objective by using radiant heat radiated from the steel-laid ladle. And to provide a more accurate and more economical way to measure the size of molten steel molten steel, its purpose is to.

The present invention is a method for stirring the molten steel contained in the ladle by a low odor method,

Providing a tube over the ladle so that at least a portion thereof absorbs the radiant heat of the ladle, and each having a thermocouple capable of measuring the temperature of the molten steel and the temperature of the slag;

The gas is drawn through the bottom of the ladle in which the molten steel is taken, the molten steel is agitated, and the Ao _steel is measured while supplying a liquid having a known specific heat through the tube at a constant flow rate (V), and the ladle Measuring the temperature (T ₁ ) of the liquid before the radiant heat is absorbed and the temperature (T ₂ ) of the liquid after the radiant heat of the ladle is absorbed to obtain a solution temperature difference (ΔT);

Obtaining a radiated amount of heat (Q _rad ) by the following formula (1) using the flow rate (V) and the solution temperature difference (ΔT) of the liquid;

Q _rad = Specific Heat × V × ΔT

Obtaining a constant (C) by the following formula (2) using the calorific value (Q _rad ) obtained as described above, the temperature of the molten steel and the slag temperature and the ao _steel size measured by the thermocouple; And

[A _Ladle : Upper Area of _Ladle ]

Measure the flow rate (V) of the liquid passing through the tube during actual ground measurement, calculate the temperature difference (ΔT) and the heat absorbed heat (Q _rad ) as above, and substitute the values in the following equation (3) ,

The present invention relates to a method for measuring the size of molten steel in a ladle including a step of obtaining a size of a _steel (A _steel ).

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

If the position and specifications of the nozzle through which the gas is discharged are the same, the uniformity of molten steel is directly related to the stirring power. The stirring power is expressed by the following formula (4).

[ε: stirring power on molten steel

Q ₀ : flow rate of molten steel

P ₂ : Pressure at the nozzle outlet

T ₁ : temperature at gas blowing

T ₂ : temperature of molten steel]

As can be seen from Equation (4), if all conditions are the same, the flow rate must be increased to increase the stirring power.

However, when blowing gas through a porous plug installed in the bottom of the ladle, it is difficult to know the blown flow rate.

That is, as shown in FIG. 2, the porous plug is actually caused by the outflow of the gas through the joint 5 of the pipe, the outflow of the gas at the nozzle connection 6, the outflow of the gas through the crack 7 inside the nozzle, and the like. The flow rate of the gas blown through is different from the value shown through the flow meter. However, the actual flow rate has an important meaning because it is necessary to know the flow rate of the gas actually blown so that the operation can be controlled within the appropriate stirring power range as shown in Equation (4) above.

Therefore, even though it is impossible to directly grasp the actual flow rate, it is necessary to know the value of the flow rate introduced through indirect information.

When gas is blown through the nozzle, a gas-liquid coexistence region of the type shown in FIG. 1 is generated.

The spread angle of the gas-liquid coexistence region of FIG. 1 has a relationship with the actual flow rate of the blown gas as shown in Equation (5) below.

[θ: spread angle (rad) of gas-liquid coexistence area

v: linear velocity of gas at the tip of nozzle

g: acceleration of gravity

H: depth from the molten steel upper surface to the nozzle

ρ _g, ρ _1: density of gas and molten steel, respectively

D: diameter of the upper surface of the molten steel

d _n : nozzle diameter]

In addition, the upper portion of the gas-liquid coexistence area is a slag where the slag is pushed out due to the upward flow and only molten steel and bubbles exist.

The size of the grains depends on the spread angle of the gas-liquid coexistence region by the relationship of equation (5), and the spread angle of the gas-liquid coexistence region depends on the actual blowing flow rate.

Therefore, knowing the size of the molasses has the same effect as knowing the actual flow rate value. In practice, when the molten steel is stirred by the low odor method, the size of the molasses is often used as the working standard.

In other words, the above theory is briefly explained, because the power for homogenizing the molten steel depends on the flow rate of the molten steel when the other conditions are constant, and when the molten steel flow rate is the same, the size of the molten metal generated on the surface of the molten steel becomes the same. In order to control the stirring power of molten steel, it is used as a criterion to grasp the size of the rattle which is relatively easy to identify.

However, as described above, the size of the yaktang is currently determined only by the naked eye, and its determination accuracy is low, and the operator must move to the point where it is easy to observe.

The above problems can be solved by automatically measuring the object by a method so that the operator can receive information quickly at the workplace.

Therefore, the present invention will be described in detail with reference to Figure 3 to solve the above problems are as follows.

According to the present invention, in order to measure the size of the molten steel at the time of low stirring of the molten steel received on the ladle, at least a part of the ladle absorbs the radiant heat of the ladle 1 in which the molten steel 2 is received. The tube 10 is provided on (1), and the thermocouples 11 and 12 which can measure the temperature of the molten steel 20 and the temperature of the slag 30 are provided, respectively.

An entrance thermometer 11 for measuring the temperature T1 of the liquid before the radiant heat of the ladle 1 is absorbed and for measuring the temperature T2 of the liquid after the radiant heat of the ladle 1 is absorbed. The pipe 10 is provided with an exit thermometer 12 and a flow meter 13 for measuring the flow rate of the solution.

In addition, it is preferable to provide a radiant heat shield plate 14 below the entrance thermometer 11 and the exit thermometer 12 so that radiant heat of molten steel is not directly transmitted to the thermometer.

It is preferable to use an aluminum plate as the radiation shielding plate.

In Fig. 3, reference numeral 15 denotes a valve and 16 and 17 denote support members.

Next, the molten steel is stirred through the bottom of the ladle 1 in which the molten steel 2 is received, and the molten steel is agitated, and the liquid level while supplying a liquid having a known specific heat through the pipe 10 at a constant flow rate V. The size (Ao _steel ) is measured, and the temperature T1 of the liquid before the radiant heat of the ladle is absorbed by the entrance thermometer 11, and the temperature T2 of the liquid after the radiant heat of the ladle is absorbed. The exit thermometer 12 is measured and the solution temperature difference ΔT is obtained.

It is preferable to use water as the liquid.

Next, using the flow rate (V) and the solution temperature difference (ΔT) of the liquid, the amount of heat absorbed (Q _rad ) radiated by the following equation (1) is obtained.

(Equation 1)

Q _rad = Specific Heat × V × ΔT

Using the heat quantity (Q _rad ) obtained as described above, the temperature of the molten _steel (T _steel ) and the slag temperature (T _slag ) and Natang size (Ao _steel ) measured by the thermocouple according to the formula (2) Obtain C)

(Equation 2)

In practice, the flow rate (V) of the liquid passing through the pipe is measured using the flowmeter (13), and the temperature difference (ΔT) and the radiation absorbed heat quantity (Q _rad ) are obtained as described above, and the values are obtained. Substituting into the following Equation (3), Natang size (A _steel ) is obtained.

(Equation 3)

As can be seen from FIG. 4 which shows the correlation between the measured value of molten steel of molten steel and the actually measured value according to the present invention, the measured value of molten steel of molten steel according to the present invention and the value actually measured show a fairly good correlation. have.

As described above, the present invention has the effect of measuring the size of molten steel more objectively, more accurately and more economically by using radiant heat radiated from the ladle in which molten steel is taken.

Claims (1)

In the method of stirring the molten steel contained in the ladle by a low odor method, Providing a tube over the ladle so that at least a portion thereof absorbs the radiant heat of the ladle, and each having a thermocouple capable of measuring the temperature of the molten steel and the temperature of the slag; The gas is drawn through the bottom of the ladle in which the molten steel is taken, the molten steel is agitated, and the Ao _steel is measured while supplying a liquid having a known specific heat through the tube at a constant flow rate (V), and the ladle Measuring the temperature (T ₁ ) of the liquid before the radiant heat is absorbed and the temperature (T ₂ ) of the liquid after the radiant heat of the ladle is absorbed to obtain a solution temperature difference (ΔT); Obtaining a radiated amount of heat (Q _rad ) by the following formula (1) using the flow rate (V) and the solution temperature difference (ΔT) of the liquid; (Equation 1) Q _rad = Specific Heat × V × ΔT Obtaining a constant (C) by the following formula (2) using the calorific value (Q _rad ) obtained as described above, the temperature of the molten steel and the slag temperature and the ao _steel size measured by the thermocouple; And (Equation 2)

[Where, Ao _steel : measurement size of tongue, T _steel : temperature of molten _steel , T _slag : temperature of slag, Q _rad : amount of heat absorbed by radiation, A _Ladle : upper area of _ladle ] Measure the flow rate (V) of the liquid passing through the tube during actual ground measurement, calculate the temperature difference (ΔT) and the heat absorbed heat (Q _rad ) as above, and substitute the values in the following equation (3) , (Equation 3)

[Where, A _steel : Natang size, T _steel : Molten _steel temperature, T _slag : Slag temperature, Q _rad : Radiation absorbed heat, A _Ladle : _Ladle upper area] Method for measuring the size of molten steel in the ladle comprising the step of obtaining the size of the _steel (A _steel )

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