JP2023065224A - Method for estimating real flow rate of inert gas fed to molten steel in immersion nozzle - Google Patents

Abstract

To provide a method for estimating a real flow rate of an inert gas fed to a molten steel in an immersion nozzle upon continuous casting of the molten steel.SOLUTION: A method for estimating a real flow rate of an inert gas fed to a molten steel in an immersion nozzle when the molten steel is fed from an intermediate container to a mold via a sliding gate and an immersion nozzle at a time of continuous casting of the molten steel, and, when an inert gas is blown into the immersion nozzle, includes: previously obtaining a relation between the real flow rate of the inert gas fed to the molten steel in the immersion nozzle and an opening degree of the sliding gate in accordance with the throughput of the molten steel; and estimating the real flow rate of the inert gas fed to the molten steel in the immersion nozzle from the opening degree of the sliding gate, the throughput of the molten steel and the previously obtained relation at the time of continuous casting of the molten steel.SELECTED DRAWING: Figure 3

Description

In the present application, during continuous casting of molten steel, molten steel is supplied from the tundish to the mold through a sliding gate (hereinafter sometimes abbreviated as "SG") and an immersion nozzle, and an undesired state is formed in the immersion nozzle. A method is disclosed for estimating the actual flow rate of inert gas supplied to molten steel in a submerged nozzle when active gas is blown.

In Patent Document 1, during continuous casting of molten steel, when molten steel is supplied from a tundish to a mold through a sliding gate and an immersion nozzle and an inert gas is blown into the immersion nozzle, the sliding gate is opened. A method is disclosed for controlling a valve that regulates the flow rate of inert gas based on the change in temperature to adjust the flow rate of inert gas blown into a submerged nozzle.

JP-A-6-031413

In a continuous casting machine, inert gas leaks from a fitting portion between a refractory and an inert gas blowing mechanism. However, the actual amount of leakage is unknown, and it is currently impossible to measure the actual flow rate of the inert gas supplied to the molten steel in the submerged nozzle. Therefore, even if the flow rate of the inert gas blown into the submerged nozzle is adjusted by the method disclosed in Patent Document 1, the inert gas is not supplied to the molten steel in the submerged nozzle at the targeted flow rate. I don't know if In this regard, there is a need for a method of estimating the actual flow rate of the inert gas supplied to the molten steel in the submerged nozzle.

This application, as one of the means for solving the above problems,
During continuous casting of molten steel, when the molten steel is supplied from an intermediate vessel to the mold through a sliding gate and an immersion nozzle, and an inert gas is blown into the immersion nozzle, the molten steel in the immersion nozzle A method for estimating the actual flow rate of the inert gas supplied with
The relationship between the actual flow rate of the inert gas supplied to the molten steel in the immersion nozzle and the opening degree of the sliding gate (hereinafter sometimes abbreviated as "SG opening degree") is the throughput of the molten steel. (Through Put, hereinafter sometimes abbreviated as "TP"), and
During continuous casting of the molten steel, the actual flow rate of the inert gas supplied to the molten steel in the immersion nozzle is calculated from the opening degree of the sliding gate, the throughput of the molten steel, and the previously obtained relationship. to estimate,
disclose a method comprising

In the method of the present disclosure, the relationship may be obtained in advance by model experiments using low-melting-point metals.

According to the technique of the present disclosure, it is possible to estimate the actual flow rate of the inert gas supplied to the molten steel within the submerged nozzle.

1 schematically shows a state in which molten steel is supplied from an intermediate vessel to a mold through a sliding gate and an immersion nozzle during continuous casting of molten steel, and an inert gas is blown into the immersion nozzle. 2 shows the flow of the method of the present disclosure; 4 schematically shows the relationship between the opening degree of the sliding gate and the inert gas supply flow rate at a given molten steel throughput. The configuration of a model experimental device using a low-melting-point metal is schematically shown. FIG. 4 is a schematic diagram for explaining measurement of pressure loss; FIG. 4 is a schematic diagram for explaining a concept of a method for estimating an actual flow rate of inert gas supplied to a flow path; FIG. 4 is a schematic diagram for explaining a concept of a method for estimating an actual flow rate of inert gas supplied to a flow path; The relationship between SG opening and pressure loss and the relationship between inert gas flow rate and pressure loss are shown. FIG. 5 is a diagram for explaining an example of a change in SG opening due to inert gas blowing;

The method of the present disclosure, as shown in FIG. This is a method of estimating the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the submerged nozzle 40 when the inert gas 60 is blown inside. As shown in FIG. 2 , the method S10 of the present disclosure determines the relationship between the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the submerged nozzle 40 and the opening degree of the sliding gate 30. Obtaining in advance according to the throughput (step S1), and during continuous casting of the molten steel 10, from the opening degree of the sliding gate 30, the throughput of the molten steel 10, and the previously obtained relationship, the molten steel in the immersion nozzle 40 estimating the actual flow rate of inert gas 60 supplied to 10 (step S2).

1. process S1
In step S<b>1 , the relationship between the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the submerged nozzle 40 and the opening degree of the sliding gate 30 is obtained in advance according to the throughput of the molten steel 10 . "Actual flow rate of inert gas supplied to molten steel in the submerged nozzle" is the flow rate of inert gas blown into the submerged nozzle minus the amount leaked outside the submerged nozzle. Refers to the flow rate actually supplied to the molten steel.

As shown in FIGS. 1 and 3A, in the continuous casting of the molten steel 10, the molten steel 10 surface position M1 in the intermediate container (for example, tundish) ₂₀ and the molten steel 10 surface position in the mold 50 The opening degree of the sliding gate 30 can be controlled so that the throughput TP of the molten steel 10 reaches the target value while maintaining the height H between the position _M2 . For example, by maintaining the opening degree of the sliding gate 30 while maintaining the height H, the throughput TP of the molten steel 10 can be maintained constant. If it is desired to increase the throughput TP of the molten steel 10, the opening degree of the sliding gate 30 is increased while maintaining the height H, and if it is desired to decrease the throughput TP of the molten steel 10, the sliding gate is maintained while maintaining the height H. Decrease the opening of 30.

In such a case, as shown in FIG. 3B, when inert gas 60 is blown into submerged nozzle 40, inert gas 60 actually supplied to molten steel 10 without leaking to the outside A pressure loss occurs by the amount of . That is, in order to maintain the throughput TP of the molten steel 10 when the inert gas 60 is blown into the immersion nozzle 40, the sliding It is necessary to increase the opening of gate 30 . In other words, there is a predetermined correlation between the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the immersion nozzle 40 and the opening degree of the sliding gate 30 according to the throughput TP of the molten steel 10. exist.

The relationship between the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the immersion nozzle 40 and the opening degree of the sliding gate 30 may be obtained from various model experiments, numerical calculations, and the like. In particular, it is possible to obtain the relationship in advance by model experiments using low-melting-point metals (meaning metals with a melting point lower than that of steel, for example, metals with a melting point of 300° C. or lower such as Sn or Sn alloys). In model experiments using low-melting-point metals, it is possible to match non-dimensional numbers such as the Froude number, Reynolds number and Weber number with those in the molten steel system (Patent No. 6750533). It can be said that the flow state can be simulated with high accuracy. In addition, in the apparatus according to the model experiment, it is possible to create an ideal state in which there is substantially no leakage of inert gas. As a result, the relationship between the flow rate of the inert gas actually supplied to the low-melting-point metal in the submerged nozzle (=the flow rate of the inert gas blown into the submerged nozzle) and the opening of the sliding gate can be obtained. By converting this to the molten steel system, the relationship between the actual flow rate of the inert gas 60 supplied to the molten steel 10 in the immersion nozzle 40 and the opening of the sliding gate 30 can be determined. The relationship may be represented by a mathematical formula as a function of the opening degree of the sliding gate 30 and the actual flow rate of the inert gas. Specific forms of model experiments using low-melting-point metals will be described in detail in Examples.

2. process S2
In step S2, during the continuous casting of the molten steel 10, the opening of the sliding gate 30, the throughput of the molten steel 10, and the previously obtained relationship described above determine the inert gas supplied to the molten steel 10 in the submerged nozzle 40. Estimate the actual flow rate of the gas 60 .

According to the method S10 of the present disclosure, during the continuous casting of the molten steel 10, the molten steel 10 in the immersion nozzle 40 can flow into the molten steel 10 only by obtaining the information regarding the opening degree of the sliding gate 30 and the information regarding the throughput TP of the molten steel 10. The actual flow rate of supplied inert gas 60 can be estimated. The degree of opening of the sliding gate 30 and the throughput TP of the molten steel 10 can be directly or indirectly measured or specified by known methods obvious to those skilled in the art.

For example, when the molten steel 10 is continuously cast, the opening of the sliding gate 30 for maintaining a predetermined molten steel throughput TP when no inert gas is blown (FIG. 3(A)) is assumed to be the "initial opening." In this case, when the inert gas is blown while maintaining the throughput TP, the opening of the sliding gate 30 is the initial opening corresponding to the actual flow rate of the inert gas supplied to the molten steel 10 in the submerged nozzle 40. to a predetermined degree (FIG. 3(B)). In addition, even if the actual flow rate of the inert gas supplied to the molten steel 10 in the submerged nozzle 40 changes due to changes in the amount of inert gas blown or leaked, etc., the sliding The opening degree of the gate 30 changes. In other words, according to the method S10 of the present disclosure, while maintaining the throughput TP of the molten steel 10, the degree of opening of the sliding gate 30 and the amount of change in the degree of opening of the sliding gate 30 determine the amount of inert gas supplied to the molten steel 10 in the submerged nozzle 40. It is possible to estimate the flow rate and its variation. That is, "estimating the actual flow rate" in the present application includes not only the form of estimating the actual flow rate itself but also the form of estimating the amount of change in the actual flow rate.

3. Supplement The continuous casting machine and continuous casting conditions employed in method S10 of the present disclosure may be the same as conventional ones. The type (steel type) of the molten steel 10 is also not limited as long as it is an alloy containing iron. Also, the shapes of the intermediate container 20 (eg, tundish), sliding gate 30, submerged nozzle 40 and mold 50 are not particularly limited. The mechanism for blowing the inert gas 60 and the blowing position are not particularly limited. An active gas 60 may be blown, or an inert gas may be blown upstream of the sliding gate 30 . The type of inert gas is also not particularly limited, and may be argon (Ar), for example. According to the method S10 of the present disclosure, it is possible to estimate the above-mentioned actual flow rate Q without particularly introducing new equipment to a conventional continuous casting machine.

The present invention will be further described below while showing model experiments using low-melting-point metals, but the present invention is not limited to the following examples. The present invention can adopt various conditions as long as it achieves its purpose without departing from the gist thereof.

1. 1. Model experiment using low-melting-point metal 1.1 Experimental conditions Figure 4 shows an overview of the equipment used in the model experiment. The position of the sliding gate (SG), the immersion nozzle, the shape of the mold container, etc., simulate an actual continuous casting machine. In the experiment, first, the entire apparatus shown in FIG. 4 was heated and held by a heater, and the simulated tundish (supply tank) was evacuated to fill with molten Sn (melting point: 231.9° C.). The VP suction was manipulated to keep the pressure constant. Molten Sn was circulated by an electromagnetic pump MP, and the generated circulation flow rate was measured by an electromagnetic flow meter MFM. The molten metal level in the simulated mold was measured by a laser level meter LL, and various manual valves were operated to keep the molten mold level in the simulated mold constant. The pressure in the circulation device was measured with a pressure gauge. The melt surface height in the circulator was measured with a microwave level meter ML.

Argon (Ar) as an inert gas was blown from a blowing port above the SG structure attached to the submerged nozzle. The SG structure reproduces a channel in which the SG opening is fixed to a constant SG opening condition (%) as described later.

Here, the "SG opening degree" can be specified based on the stroke amount of the intermediate sliding plate of the three plates, as shown in FIG. 3, for example. Specifically, when the stroke rate of the sliding plate is SR (see formula (I) below), SG opening (%) can be specified as 100-SR. That is, when the circular hole of the sliding plate is fully open to the flow path, the stroke rate is 0% and the SG opening is 100%, and when the circular hole of the sliding plate is fully closed to the flow path, , the stroke rate is 100% and the SG opening is 0%. Similarly, for example, when the stroke rate is 75%, the SG opening is 25%. In this experiment, the SG opening was specified based on the stroke rate, but in addition, the SG opening may be specified based on the area opening. That is, of the total area (A) of the circular hole of the sliding plate, the ratio of the area a (a / A × 100%) of the part facing the flow channel (the part functioning as an opening) is specified as the SG opening You may
SR=X/ _D0 ×100% (I)
D ₀ : Hole diameter of sliding plate (mm)
X: Stroke amount (mm) of the sliding plate, which is 0 when fully open and _D0 when fully closed.

Eight holes of φ0.5 mm were evenly provided on the circumference of the tube inner wall above the SG structure. An air accumulation chamber was provided outside the submerged nozzle so as to cover the entire hole of φ0.5 mm. After the accumulating chamber was filled with Ar, it was evenly blown into the pipe from each hole without breathing. The Ar flow rate was kept constant by using a mass flow controller.

The circulating flow rate, the tundish internal pressure, the molten metal surface height in the tundish and the mold, etc. were measured when the SG opening, the blown Ar flow rate, and the electromagnetic pump output were each changed.

1.2 Measurement of Pressure Loss Amount In the above experimental system, the state before the electromagnetic pump is activated is shown in FIG. 5(A). Let p be the pressure in the tundish at this time, and let h be the height difference between the surface of the molten metal in the tundish and the surface of the mold in the mold. Next, FIG. 5B shows a state in which the electromagnetic pump is operated. The circulation flow rate of Sn circulated by the pump is Q, and the representative speed calculated therefrom is v. The increment/decrement of the tundish internal pressure at this time is Δp, and the increment/decrement of the height difference is Δh. Focusing on the space between the tundish and the mold and using Bernoulli's equation, the energy E of the fluid can be expressed as shown in the following equation (1).

E=(1/2)pv ² +Δp+ρgΔh+ε ₀ (v) (1)

where ρ is the density of the fluid and g is the gravitational acceleration. ε ₀ represents the pressure loss due to the flow path structure such as elbows, expansion/contraction, and wall friction of the flow path, and is generally expressed as a function of velocity v.

Next, the following equation (2) shows the case where the same circulation flow rate Q (that is, the same representative velocity v) as in the above equation (1) is maintained when the SG is closed or when Ar is blown. As an example, the state where SG is closed is shown in FIG. 5(C).

E+ΔE=(1/2)pv ² +Δp′+ρgΔh′+ε ₀ (v) (2)

In this case, pressure loss due to SG or Ar injection is taken into consideration, so the required energy of the fluid increases by ΔE. Therefore, the pressure increment and decrement and the height difference increment and decrement may not match the values shown in equation (1). Therefore, each notation is set to Δp' and Δh'. Considering the difference between the equations (1) and (2), the increment of fluid energy, ie, the pressure loss, can be expressed as shown in the following equation (3).

ΔE=Δp−Δp′+ρg(Δh−Δh′) (3)

In the above experimental system, all the values on the right side of Equation (3) are known or measurable, so pressure loss due to SG or Ar injection can be measured.

2. Concept of method for estimating the actual flow rate of Ar supplied to the flow path The actual flow rate of Ar in the actual machine can be estimated using the pressure loss due to the SG and Ar blowing obtained by the above equation (3). In an actual continuous casting machine, both the mold and the tundish are open to the atmosphere, so the pressure is always constant. In this state, the throughput TP, the melt surface position in the mold, and the melt surface position in the tundish are kept constant by automatic control of the SG opening. That is, the pressure loss term is the only variable term in the above equation (2), and if the other terms are constant, the pressure loss term is also constant. At this time, for example, assume casting when the pressure loss due to SG is ΔE _sg =a [kPa] at a certain throughput TP and SG opening (left side diagram in FIG. 6). Now consider the situation in which Ar is blown which causes the same pressure drop ΔE _ar =a [kPa]. In this case, it is expected that the SG will be fully opened by automatic control of the SG opening to keep the throughput TP, the melt surface position in the mold, the melt surface position in the tundish, and the pressure loss constant (Fig. 6 right side view ).

Next, let us consider a case where the actual flow rate of supplied Ar is unknown, as is the case with the actual machine. Assume casting when a certain throughput TP is maintained and the SG opening is 50%, and the pressure loss due to the SG is ΔE _sg =a [kPa] (left side diagram in FIG. 7). Now consider the situation where an unknown amount of Ar is blown. As a result, it is assumed that the SG opening is changed to 25% by automatic control. At this time, if the pressure loss due to SG is ΔE _sg '=c [kPa], the pressure loss due to the injected Ar is ΔE _ar = ac [ kPa]. That is, it can be seen that the Ar flow rate corresponding to this pressure loss was blown in as the actual flow rate (right side of FIG. 7). In addition, the concept of estimating the actual flow rate requires the SG opening at each throughput and the pressure loss due to Ar injection as reference values, but this is possible by measuring the pressure loss under each condition by model experiments. is.

3. 3. Experimental Results 3.1 Pressure Loss Due to SG Opening and Ar Injection Measured in Experimental System Based on the above concept, the SG opening and pressure loss due to Ar blowing were measured in the model experiment described above. The results are shown in FIGS. 8(A) and (B). As shown in FIGS. 8A and 8B, the pressure loss is about several kPa to several tens of kPa for both SG opening and Ar blowing, and each pressure loss is within a comparable numerical range. It's becoming

As an application example of the above concept, in the initial state (throughput TP = 4.9 [Ton / min] and SG opening = 45 [%]), SG when 0.3 [NL / min] of Ar is blown FIG. 9 shows the expected change in opening. Each numerical value in the figure is based on FIGS. 8A and 8B, which are the measurement results. The pressure loss in the initial state is only 20 [kPa] due to the SG opening (Fig. 9 (1)). From this, it can be seen that when the throughput TP and the melt surface position between the tundish and the mold are maintained by automatic control even after Ar blowing, the pressure loss applied to the system is maintained at 20 [kPa] (Fig. 9 (2) ). On the other hand, the pressure loss due to the blown Ar flow rate=0.3 [NL/min] is 9 [kPa] (FIG. 9 (3)). As a result, the SG opening changes to 52 [%] with a pressure loss of 11 [kPa] so that the sum of the SG opening and the pressure loss due to Ar blowing becomes 20 [kPa] (Fig. 9 ( 4)).

3.2 Summary As described above, in model experiments using low melting point metals, it is possible to measure the amount of pressure loss that occurs when SG is used or when Ar is blown. This is because the experimental system can accurately measure the level of the molten metal in the tundish, the level of the molten metal in the mold, the pressure in the tundish, the Ar flow rate, the SG opening, and the like. On top of that, in a model experiment, we measured the pressure loss when Ar was blown from near the top of the SG, and measured the pressure loss of the SG alone. However, depending on the SG opening, the SG pressure loss is large, so it was found that it is appropriate to estimate the Ar actual flow rate as described above. When applying this result to an actual machine, it can be said that the actual flow rate of Ar supplied to the molten steel in the submerged nozzle can be estimated from the amount of change in the SG opening during Ar blowing. This is based on the idea that the amount of pressure loss in the system is kept constant by controlling the SG opening in the actual machine. The reference values of the SG opening and the pressure loss due to Ar blowing used at this time should be obtained in advance by model experiments using low-melting-point metals as described above.

4. Investigation in Actual Machine It was indirectly confirmed by conducting a continuous casting test in an actual machine that the above estimation of the actual Ar flow rate is appropriate.

First, prior to the continuous casting test, a molten metal model experiment (model experiment using the above low-melting-point metal) simulating the continuous casting test was conducted, and the relationship between the Ar flow rate and the opening of the sliding gate at each throughput was investigated. clarified.

Next, a continuous casting test was conducted using an actual machine corresponding to the model experiment described above. Here, during continuous casting, Ar was blown only through the three-plate type sliding gate. Based on the SG opening and the relationship obtained by the model experiment, the actual flow rate of Ar blown from the sliding gate into the molten steel in the submerged nozzle is estimated, and the estimated value is set to a predetermined value. The amount of (1) nozzle clogging and (2) bubble defects on the surface layer of the cast slab was examined in cases where the blowing of the slab was controlled and when it was not controlled.

In the following continuous casting test, the casting speed of Vc = 1.5 m/min was followed by Ar blowing at 10 NL/min, and the estimated value of the actual flow rate of Ar was 1 NL/min. bottom. Here, the Ar blowing flow rate (10 NL/min) is a flow rate set for constant flow rate control by a mass flow controller installed upstream of the Ar blowing unit. The same applies hereinafter.

(1) Nozzle clogging Observe the inner wall of the submerged nozzle after continuous casting, and in the above "reference", the thickness of the layer attached to the inner wall is set to "1", and the case where there is no layer attached to the inner wall is set to "0". As a result, the thickness was indexed and evaluated as a "occlusion index".

(2) Bubble defects on cast slab surface layer In the above "criteria", the number of bubble defects present in the 10 mm surface layer of the cast slab obtained after continuous casting is set to "1", and the case where there are no bubbles at all is set to "0". After indexing, this was evaluated as the "bubble defect index".

4.1 Example 1
This is an example of the above "reference". In the continuous casting test described above, when 10 NL/min of Ar was blown at a casting speed of Vc=1.5 m/min, the estimated value of the actual flow rate of Ar was 1 NL/min. That is, it was estimated that only 1/10 of the Ar injection amount was injected as an actual flow rate.

4.2 Case of Decreased Sealability 4.2.1 Example 2
A continuous casting test was conducted in the same manner as in Example 1 after intentionally lowering the Ar sealing performance in the continuous casting machine. In this case, in the continuous casting test, when 10 NL/min of Ar was blown at a casting speed of Vc=1.5 m/min, the estimated value of the actual flow rate of Ar was 0.5 NL/min. That is, it was presumed that the actual flow rate of Ar was only 1/2 of Example 1. Continuous casting was performed while maintaining such a state.

4.2.2 Example 3
In the same continuous casting machine as in Example 2, when the Ar blowing flow rate was increased to optimize the estimated value of the actual Ar flow rate, the estimated value was became 1.0 NL/min. Continuous casting was performed while maintaining the estimated value at 1.0 NL/min.

4.3 Case of Enhanced Sealability 4.3.1 Example 4
A continuous casting test was conducted in the same manner as in Example 1 after intentionally enhancing the Ar sealing performance in the continuous casting machine. In this case, in the continuous casting test, when 10 NL/min of Ar was blown at a casting speed of Vc=1.5 m/min, the estimated value of the actual flow rate of Ar was 2 NL/min. That is, it was presumed that Ar was injected at an actual flow rate twice that of Example 1. Continuous casting was performed while maintaining such a state.

4.3.2 Example 5
In the same continuous casting machine as in Example 4, when the Ar injection flow rate was decreased in order to optimize the estimated value of the actual Ar flow rate, the estimated Ar flow rate was reduced to 5 NL / min. The value became 1.0 NL/min. Continuous casting was performed while maintaining the estimated value at 1.0 NL/min.

4.4 Evaluation Results Table 1 below shows the evaluation results of the clogging index and the bubble defect index for Examples 1-5.

As is clear from the results shown in Table 1, regardless of the Ar sealing property in the continuous casting machine, the blockage index can be obtained by changing the Ar blowing set flow rate so that the estimated value of the Ar actual flow rate is 1 NL / min. Similar results to those of reference Example 1 were obtained for both the foam defect index and the bubble defect index (Examples 3 and 5). This can be said to prove that the estimation of the actual Ar flow rate was appropriate.

On the other hand, in Example 2 in which the estimated value of the actual Ar flow rate was maintained at 0.5 NL/min, the bubble defect index decreased and the clogging index increased compared to Example 1 serving as the reference. This can be said to be the result of a decrease in the number of bubbles in the molten steel due to a decrease in the actual flow rate of Ar supplied to the molten steel, and a decrease in the effect of floating and removing inclusions. It can be said that it proved that it was appropriate.

In addition, in Example 4 in which the estimated value of the actual Ar flow rate was maintained at 2 NL/min, the clogging index decreased, but the bubble defect index increased compared to Example 1, which serves as the reference. This can be said to be the result of an increase in the number of bubbles in the molten steel, while the increase in the actual flow rate of Ar supplied to the molten steel improves the effect of removing inclusions and the like. It can be said that it proved that it was.

Based on the above results, the relationship between the actual flow rate of the inert gas supplied to the molten steel in the submerged nozzle and the SG opening is obtained in advance according to the molten steel throughput based on low-melting-point metal model experiments and the like. By doing so, during the actual operation of continuous casting, from the relationship obtained in advance with the SG opening, the throughput of molten steel, and the relationship obtained in advance, a reasonable estimate as the actual flow rate of the inert gas supplied to the molten steel in the submerged nozzle It can be said that the value can be obtained. In this way, according to the technique of the present disclosure, it is possible to appropriately estimate the actual state of inert gas blowing into the molten steel in the submerged nozzle. appropriate blowing becomes possible.

10 Molten Steel 20 Intermediate Container 30 Sliding Gate 40 Immersion Nozzle 50 Mold 60 Inert Gas

Claims (2)

During continuous casting of molten steel, when the molten steel is supplied from an intermediate vessel to the mold through a sliding gate and an immersion nozzle, and an inert gas is blown into the immersion nozzle, the molten steel in the immersion nozzle A method for estimating the actual flow rate of the inert gas supplied with
determining in advance the relationship between the actual flow rate of the inert gas supplied to the molten steel in the immersion nozzle and the opening degree of the sliding gate according to the throughput of the molten steel;
During continuous casting of the molten steel, the actual flow rate of the inert gas supplied to the molten steel in the immersion nozzle is calculated from the opening degree of the sliding gate, the throughput of the molten steel, and the previously obtained relationship. to estimate,
method including. Determine the relationship in advance by a model experiment using a low melting point metal,
The method of claim 1.

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