KR101588092B1 - Apparatus and method for predicting aluminum quantity in vacuum oxygen decarburization - Google Patents

Abstract

The present invention relates to a method for producing a chromium-containing molten steel, comprising the steps of: preparing a molten steel containing chrome by decarburizing and decarburizing oxygen and deoxidizing the molten steel by using aluminum; Setting a first relationship between the amount of chromium oxide produced and the amount of aluminum for chromium oxide reduction; Setting a second relational expression between an amount of dissolved oxygen in the molten steel after the oxygen blowing and an amount of aluminum for removing the dissolved oxygen; Setting a third relationship between a target aluminum concentration of the molten steel and an amount of aluminum for component adjustment; And deriving a regression equation for predicting the amount of aluminum input in the deoxidation step by regression analysis of the first through third relational expressions and the process factors considered in the VOD process, and a method for predicting the aluminum injection amount in the vacuum refining process to provide.

Description

TECHNICAL FIELD The present invention relates to a method for predicting the amount of aluminum in a vacuum refining process,

The present invention relates to a method and an apparatus for predicting the amount of aluminum to be introduced during a deoxidation process using aluminum in a vacuum refining process with aluminum.

In a vacuum refining process (Vacuum Oxygen Decarburization (VOD)) for producing ferritic stainless steels containing chromium, stainless steel containing chromium supplies oxygen to molten steel for decarburization, in which not only carbon but also chromium . In addition, a part of the supplied oxygen flows into the molten steel and exists. Therefore, after the decarburization process, a deoxidizing agent is added to reduce the oxidized chromium, and a deoxidation step is performed to remove oxygen present in the molten steel.

At this time, setting of the amount of aluminum, which is a deoxidizer to be added for deoxidation, is important. If the amount of aluminum is insufficient, the cleanliness of the steel becomes poor due to dissolved oxygen. If the amount of aluminum is excessive, the manufacturing cost rises more than necessary. Further, since the aluminum must be removed by blowing oxygen again, And reacts again with the re-injected oxygen, which causes the degree of cleanliness of molten steel due to a large amount of aluminum oxide to become poor.

In order to solve the problems of the prior art as described above, the present invention provides a method and apparatus for predicting the amount of aluminum in a VOD process for efficiently predicting the amount of aluminum to be supplied in a deoxidation process using aluminum in a VOD process.

Other objects of the present invention will be apparent to those skilled in the art from the following examples.

In order to accomplish the above object, according to a preferred embodiment of the present invention, there is provided a method of manufacturing a molten steel containing chromium by vacuum-degassing (Oxygen Decarburization) Setting a first relational expression between the amount of chromium oxide oxidized by using the concentration of chromium in the molten steel before and after the oxygen blowing and the amount of aluminum for chromium oxide reduction in the process; Setting a second relational expression between an amount of dissolved oxygen in the molten steel after the oxygen blowing and an amount of aluminum for removing the dissolved oxygen; Setting a third relationship between a target aluminum concentration of the molten steel and an amount of aluminum for component adjustment; And deriving a regression equation for predicting the amount of aluminum in the deoxidation step by regression analysis taking into consideration the first through third relational expressions and the process parameters considered in the VOD process, and estimating aluminum input amount in a vacuum refining process Method is provided.

The process parameters may include at least one of the molten steel temperature before and after the oxygen blowing, the amount of the temperature raising agent, the amount of slag excluded from the molten steel before the VOD process, and the number of uses of the molten steel during the VOD process.

The dissolved oxygen amount can be calculated by excluding the amount of the heated oxygen amount, the amount of decarbonated oxygen, the amount of unreacted oxygen, and the amount of chromium oxide in the total oxygen supplied amount in the VOD process.

The amount of temperature-elevated oxygen oxide may be calculated using the amount of the temperature-elevator supplied to the molten steel.

The decarbonized oxygen amount can be calculated using the carbon concentration before and after the oxygen blowing.

The regression equation for predicting the input amount of aluminum can be calculated as follows.

[Regression formula]

The amount of aluminum supplied = -R 1 + R 2 × (concentration of chromium before oxygen drawing (%) - concentration of chromium (%) after oxygen drawing) + R 3 × amount of aluminum dissolved oxygen - R 4 × target aluminum concentration + R 5 × amount of molten steel + The temperature of the molten steel before shunting + R7 × the amount of heating agent input - R8 × the amount of slag excluded + R9 × the temperature of the molten steel after the blasting of oxygen - R10 × the number of uses of ladle. Where R1 to R10 are coefficients obtained by regression analysis.

Obtaining at least one of data on the amount of molten steel before the oxygen blowing, the concentration of carbon in the molten steel and the chromium concentration, the temperature of the molten steel before the melting, the amount of the temperature raising agent, the excluded slag amount, And obtaining at least one of the carbon concentration and the chromium concentration in the molten steel after the oxygen blowing and the total oxygen supplied amount, the target aluminum concentration, and the temperature of the molten steel after the blowing.

And estimating an input amount of aluminum using the obtained data and the first to third relational expressions and the regression formula.

According to another embodiment of the present invention, there is provided a method for producing a chromium-containing molten steel, comprising the steps of: (a) vacuum-deoxidizing (VOD) A first relational expression between the amount of chromium oxide oxidized by using the chromium concentration in molten steel and the amount of aluminum for chromium oxide reduction; A second relational expression between an amount of dissolved oxygen in the molten steel after the oxygen blowing and an amount of aluminum for removing the dissolved oxygen; And a relational expression setting unit for setting a third relational expression between the target aluminum concentration of the molten steel and the aluminum amount for adjusting the composition; And a regression equation deriving unit for deriving a regression equation for predicting the amount of aluminum in the deoxidation step by regression analysis considering the first through third relational expressions and process factors considered in the VOD process.

According to the present invention, by predicting the aluminum input amount in consideration of the VOD process factors, excessive aluminum is prevented from being input in the deoxidation step.

FIG. 1 is a graph showing the relationship between the measured temperature and the amount of aluminum input after oxygen-blowing in accordance with an embodiment of the present invention.
FIG. 2 is a graph showing a relationship between the amount of slag and the amount of dissolved oxygen present in the steel for VOD process according to an embodiment of the present invention. Referring to FIG.
FIG. 3 is a graph showing a relationship between the number of times the molten steel is used in the VOD process and the amount of aluminum input in the deoxidation step according to an embodiment of the present invention.
4 is a diagram illustrating an apparatus for predicting the amount of aluminum depleted in a VOD process according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating an embodiment of a method for predicting aluminum depletion in a VOD process according to an embodiment of the present invention. Referring to FIG.
6 is a graph showing the relationship between the input amount of aluminum predicted by using the regression equation according to an embodiment of the present invention and the amount of aluminum injected in the actual deoxidization step.

The details of other embodiments are included in the detailed description and drawings.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

A method and apparatus for predicting the amount of aluminum charged during deoxidation in a Vacuum Oxygen Decarburization (hereinafter referred to as VOD) process in which oxygen is blown and decarburized to produce molten steel containing chromium and deoxidation is performed using aluminum .

In more detail, a regression equation for efficiently estimating the input amount of aluminum is calculated, and the data obtained at the start of operation in the VOD process, the data acquired after oxygen blasting, and the regression equation are used to calculate the total amount of aluminum Is calculated.

During the VOD process, the decarbonization of the molten steel is mainly performed by the supplied oxygen in the high carbon region which is the initial stage of the blowing process, but the oxidation reaction of the chromium in the molten steel is mainly performed in the low carbon region which is the end of the blowing process. The chromium oxide generated by the oxidation reaction is also used for the decarburization reaction as an oxygen source of molten steel.

In the deoxidation step of removing oxygen in the molten steel, the deoxidation process is carried out with aluminum or silicon according to various components. The present invention relates to the case where aluminum is used as a deoxidizer, and the present invention will be described below based on aluminum.

First, the amount of aluminum introduced in the deoxidation step can be expressed by the following equation (1).

[Equation 1]

Aluminum input amount = amount of aluminum for chromium oxide reduction + amount of aluminum for removing dissolved oxygen + amount of aluminum for adjusting component of molten steel

That is, as can be seen from Equation (1), the amount of aluminum to be added in the deoxidation step depends on the amount of aluminum to reduce the chromium oxide, the amount of aluminum to remove dissolved oxygen remaining in the molten steel, Can be determined by the amount of aluminum for adjustment.

In the above formula (1), the amount of aluminum for chromium oxide reduction can be calculated using the reaction formula of chromium and aluminum after converting the amount of oxygen (volume) used for chromium oxidation into the molecular weight in molar units, The chromium concentration before and after oxygen blowing can be calculated and converted into the amount of gas per mole.

That is, the amount of aluminum for chromium oxide reduction can be calculated through a first relational expression between the amount of chromium oxide oxidized by using the chromium concentration in the molten steel before and after oxygen blowing, which can be expressed by the following equation (2).

&Quot; (2) "

Amount of aluminum for chromium oxide reduction = amount of chromium oxide / 33.6 x (27 x 2)

The amount of chromium oxide oxidized = (the chromium concentration before oxygen toughening (%) - the chromium concentration (%) after oxygen toughening) / 100 x amount of molten steel x (33.6 / 104)

As can be seen from the above equation (2), in order to determine the amount of aluminum for chromium oxide reduction, data of chromium concentration and molten amount in molten steel before and after oxygen blowing in the VOD process are required.

Then, the amount of aluminum for removing dissolved oxygen in Equation (1) is an amount that is required to be put in order to react and remove oxygen remaining in the molten steel with aluminum, and the amount of dissolved oxygen (volume) , And a reaction formula of aluminum and oxygen.

That is, the amount of dissolved oxygen for removing dissolved oxygen can be calculated through a second relationship with the amount of dissolved oxygen in the molten steel after oxygen blowing, which can be expressed by the following equation (3).

&Quot; (3) "

Amount of aluminum for removing dissolved oxygen = dissolved oxygen amount / 33.6 x (27 x 2)

Here, the relational expression for the dissolved oxygen amount can be expressed by Equation (4) below.

&Quot; (4) "

Dissolved oxygen amount = total oxygen supply amount - (amount of oxygenated oxygen + amount of decarbonated oxygen + amount of unreacted oxygen + amount of chromium oxide)

Aluminum can be used as the temperature-raising agent shown in Equation (4), and the relational expression for the amount of heated oxygen oxide, decarbonized oxygen, and unreacted oxygen can be expressed by Equation (5) below.

&Quot; (5) "

The amount of oxygenated oxygen at the time of heating = the amount of the heated oxygen amount × 33.6 / 54

Decarbonized oxygen amount = (carbon concentration before oxygen toughening (%) - carbon concentration (%) after oxygen toughening) / 100 x amount of molten steel x (22.4 / 12)

Unreacted oxygen amount = total oxygen supply amount 占 0.1%

Here, the temperature-elevated oxygen oxidizing amount is calculated by converting the amount of oxygen used for oxidizing the introduced heating oxidizing amount into the amount of gas per mole. The decarbonized oxygen amount is calculated by converting the amount of oxygen used to oxidize it to the amount of gas per mole based on the carbon concentration before and after the oxygen toughening. The amount of unreacted oxygen can not contribute to decarburization or chromium oxidation in the amount of oxygen supplied through the oxygen uptake lance of the VOD facility, and is assumed to be 0.1% of the total oxygen supply amount in the present invention. However, depending on the environment of the VOD equipment Can be set differently.

As can be seen from the above equations (3) to (5), in order to obtain the amount of aluminum for removing dissolved oxygen, data of total oxygen supply amount, amount of temperature increase agent, carbon concentration before and after oxygen addition, amount of molten steel, .

Next, the amount of aluminum for component adjustment in Equation (1) can be calculated through a third relational expression between the target aluminum concentration and the amount of molten steel, which can be expressed by Equation (6) below.

&Quot; (6) "

Amount of aluminum for composition adjustment = target aluminum concentration (%) / 100 × amount of molten steel

However, the amount of aluminum introduced during deoxidization, calculated using Equation 1 using the first relationship (Equation 2), the second relation (Equation 3) and the third relation (Equation 6) Due to various conditions such as facilities, the rate of error of aluminum input is not 100%. Therefore, there is a need to consider additional VOD process factors related to aluminum input in addition to the above relationship.

FIG. 1 is a graph showing the relationship between the measured temperature and the amount of aluminum input after oxygen-blowing in accordance with an embodiment of the present invention.

Referring to FIG. 1, it can be seen that the higher the temperature of the molten steel after oxygen blowing, the greater the amount of aluminum introduced in the deoxidation step. Since the molten steel temperature after the oxygen blowing is also related to the temperature of the molten steel before the oxygen blowing, the amount of the molten steel after the oxygen blowing should be taken into consideration in consideration of the amount of aluminum supplied in the deoxidation step. These factors can be obtained as process data in the VOD process.

FIG. 2 is a graph showing a relationship between the amount of slag and the amount of dissolved oxygen present in the steel for VOD process according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 2, since the amount of dissolved oxygen is higher as the amount of discharged slag is higher, the amount of slag discharged should be considered when considering the amount of aluminum in the deoxidation step. This data can also be obtained from the process data before the VOD process.

FIG. 3 is a graph showing a relationship between the number of times the molten steel is used in the VOD process and the amount of aluminum input in the deoxidation step according to an embodiment of the present invention.

Referring to FIG. 3, it can be seen that the greater the number of times the ladle is used, the more the amount of aluminum is reduced in the deoxidation step. This is because aluminum oxide used in the previous step remains on the ladle, and thus the amount of aluminum is gradually decreased. Therefore, the number of ladle cycles used in determining the amount of aluminum input in the deoxidation step is a factor to be considered, which can be obtained from the VOD process data.

1 to 3, in order to accurately calculate the amount of aluminum to be supplied during the deoxidation, in addition to the relational formulas 1 to 3, the molten steel temperature before and after the oxygen blowing process, the amount of the temperature increase agent, At least one of the amount of slag to be excluded and the number of times the molten steel is used in the VOD process.

In the present invention, Equation (7), which is a regression equation for predicting the amount of aluminum input in the deoxidation step, is derived as follows by regression analysis in consideration of the first to third relational expressions and the third relational expression and process factors.

&Quot; (7) "

The amount of aluminum supplied = -R 1 + R 2 × (concentration of chromium before oxygen drawing (%) - concentration of chromium (%) after oxygen drawing) + R 3 × amount of aluminum dissolved oxygen - R 4 × target aluminum concentration + R 5 × amount of molten steel + Temperature of pre-casting molten steel + R7 × amount of heating agent -R8 × amount of slag excluded + R9 × temperature of molten steel after oxygen blowing - R10 × number of times of use of ladle.

Here, R1 to R10 are coefficients obtained by regression analysis. R1 is -8404, R2 is 87, R3 is 0.124, R4 is 1.37, R5 is 0.0158, R6 is 1.21, R7 is 0.864, R8 is 0.0162, R9 is 3.39 , And R10 was 2.95.

In addition, R-Sq = 91.8 (%) and R-Sq (adj) = 79.4 in the regression equation.

FIG. 4 is a diagram illustrating an apparatus for predicting the amount of aluminum depleted in a VOD process according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a method for predicting the amount of aluminum depleted in a VOD process according to an embodiment of the present invention. Fig.

The aluminum deoxidation prediction apparatus 100 may include a relational expression setting unit 110, a regression formula deriving unit 120, a data obtaining unit 130, and an aluminum injection amount predicting unit 140, Will be described with reference to Fig.

Referring to FIG. 6, in step S100, the relational expression setting unit 110 sets a first relational expression between the amount of chromium oxygen calculated using the chromium concentration in the molten steel before and after the oxygen blowing and the amount of aluminum for chromium oxide reduction. Here, the first relational expression may be set as in Equation (2).

In step S200, the relational expression setting unit 110 sets a second relational expression between the amount of dissolved oxygen in the molten steel after the oxygen blowing and the amount of aluminum for removing the dissolved oxygen. Here, the second relational expression may be set as in Equation (3).

In step S300, the relational expression setting unit 110 sets a third relational expression between the target aluminum concentration of the molten steel and the aluminum amount for component adjustment. Here, the third relation can be set as shown in Equation (6).

In step S400, the regression derivation unit 120 derives a regression equation for predicting the amount of aluminum input in the deoxidation step by regression analysis in consideration of the first through third relational expressions and process factors considered in the VOD process.

Here, the process parameters may include at least one of molten steel temperature before and after oxygen blowing, amount of temperature raising agent, amount of slag removed from the molten steel before the VOD process, and the number of times the molten steel is used in the VOD process .

In step S500, the data acquiring unit 130 acquires the amount of molten steel before the oxygen blowing, the carbon concentration and chromium concentration in the molten steel, the temperature of the molten steel before the blowing, the amount of the temperature raising agent, the amount of slag to be excluded, And acquires at least one of the number of times.

In step S600, the data obtaining unit 130 obtains at least one of the carbon concentration and the chromium concentration in the molten steel after the oxygen sweeping, the total amount of supplied oxygen, the target aluminum concentration, and the temperature of the molten steel after the sweeping .

In step S700, the aluminum injection amount predicting unit 140 predicts the input amount of aluminum using the data obtained in the steps S500 and S600, the first to third relational expressions and the regression formula.

6 is a graph showing the relationship between the input amount of aluminum predicted by using the regression equation according to an embodiment of the present invention and the amount of aluminum injected in the actual deoxidization step.

Referring to FIG. 6, it can be seen that the amount of aluminum introduced by the regression equation is substantially equal to the amount of aluminum actually injected.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: Aluminum deoxidation amount predicting apparatus 110: Relation setting unit
120: regression formula setting unit 130: data obtaining unit
140: Aluminum charge prediction unit

Claims (13)

In a Vacuum Oxygen Decarburization (VOD) process in which oxygen is blown and decarburized to produce molten steel containing chromium and deoxidation is performed using aluminum,
Setting a first relationship between the amount of chromium oxide oxidized by using the chromium concentration in the molten steel before and after the oxygen blowing and the amount of aluminum for chromium oxide reduction;
Setting a second relational expression between an amount of dissolved oxygen in the molten steel after the oxygen blowing and an amount of aluminum for removing the dissolved oxygen;
Setting a third relationship between a target aluminum concentration of the molten steel and an amount of aluminum for component adjustment; And
Deriving a regression equation for predicting the amount of aluminum in the deoxidation step through a regression analysis taking into consideration the first through third relational expressions and process factors considered in the VOD process,
Wherein the dissolved oxygen amount is calculated by subtracting the amount of heated oxygen oxide, the amount of decarbonized oxygen, the amount of unreacted oxygen, and the amount of chromium oxide in the total oxygen supply amount in the VOD process. The method according to claim 1,
Wherein the process parameter includes at least one of a molten steel temperature before and after the oxygen blowing, a temperature raising agent input amount, a slag amount excluded from the molten steel before the VOD process, and a use frequency of the molten steel during the VOD process A method for predicting the amount of aluminum input in a vacuum refining process. delete The method according to claim 1,
Wherein the amount of temperature-elevated oxygen oxide is calculated using an amount of the temperature-elevator supplied to the molten steel. The method according to claim 1,
Wherein the decarbonized oxygen amount is calculated using the carbon concentration before and after the oxygen blow-in. 3. The method of claim 2,
Wherein the regression equation for predicting the input amount of aluminum is calculated as follows.
[Regression formula]
The amount of aluminum supplied = -R 1 + R 2 × (concentration of chromium before oxygen drawing (%) - concentration of chromium (%) after oxygen drawing) + R 3 × amount of aluminum dissolved oxygen - R 4 × target aluminum concentration + R 5 × amount of molten steel + The temperature of the molten steel before shunting + R7 × the amount of heating agent input - R8 × the amount of slag excluded + R9 × the temperature of the molten steel after the blasting of oxygen - R10 × the number of uses of ladle.
Where R1 to R10 are coefficients obtained by regression analysis. The method according to claim 6,
Obtaining at least one of data on the amount of molten steel before the oxygen blowing, the concentration of carbon in the molten steel and the chromium concentration, the temperature of the molten steel before the melting, the amount of the temperature raising agent, the excluded slag amount, And
Further comprising the step of obtaining at least one of the carbon concentration and the chromium concentration in the molten steel after the oxygen blowing and the total oxygen supplied amount, the target aluminum concentration, and the temperature of the molten steel after the blowing, A method for predicting aluminum doses in a. 8. The method of claim 7,
And estimating an input amount of aluminum using the obtained data and the first to third relational expressions and the regression formula. In a Vacuum Oxygen Decarburization (VOD) process in which oxygen is blown and decarburized to produce molten steel containing chromium and deoxidation is performed using aluminum,
A first relational expression between the amount of chromium oxide oxidized by using the chromium concentration in the molten steel before and after oxygen blowing and the amount of aluminum for chromium oxide reduction; A second relational expression between an amount of dissolved oxygen in the molten steel after the oxygen blowing and an amount of aluminum for removing the dissolved oxygen; And a relational expression setting unit for setting a third relational expression between the target aluminum concentration of the molten steel and the aluminum amount for adjusting the composition;
And a regression equation deriving unit for deriving a regression equation for predicting the amount of aluminum in the deoxidation step by regression analysis in consideration of the first through third relational expressions and process factors considered in the VOD process,
Wherein the dissolved oxygen amount is calculated by subtracting the amount of heat-oxidized oxygen, the amount of decarbonated oxygen, the amount of unreacted oxygen, and the amount of chromium oxide in the total oxygen supplied amount in the VOD process. 10. The method of claim 9,
Wherein the process parameter includes at least one of a molten steel temperature before and after the oxygen blowing, a temperature raising agent input amount, a slag amount excluded from the molten steel before the VOD process, and a use frequency of the molten steel during the VOD process An apparatus for predicting the amount of aluminum in a vacuum refining process 11. The method of claim 10,
Wherein the regression equation for predicting the input amount of aluminum is calculated as follows.
[Regression formula]
The amount of aluminum supplied = -R 1 + R 2 × (concentration of chromium before oxygen drawing (%) - concentration of chromium (%) after oxygen drawing) + R 3 × amount of aluminum dissolved oxygen - R 4 × target aluminum concentration + R 5 × amount of molten steel + The temperature of the molten steel before shunting + R7 × the amount of heating agent input - R8 × the amount of slag excluded + R9 × the temperature of the molten steel after the blasting of oxygen - R10 × the number of uses of ladle.
Where R1 to R10 are coefficients obtained by regression analysis. 12. The method of claim 11,
At least one of data on at least one of the amount of molten steel before the oxygen blowing, the concentration of carbon in the molten steel and the chromium concentration, the temperature of the molten steel before the blowing, the amount of the temperature raising agent, the amount of slag to be excluded,
Further comprising a data acquiring section for acquiring data of at least one of a carbon concentration and a chromium concentration in the molten steel after the oxygen is blown, a total oxygen supply amount blown, a target aluminum concentration, and a temperature of the molten steel after the blowing, An apparatus for predicting the amount of aluminum in a process. 13. The method of claim 12,
Further comprising an aluminum injection amount predicting unit for predicting an input amount of aluminum by using the obtained data and the first to third relational expressions and the regression formula.

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