JP2009052082A - Method for deciding oxygen feeding flow rate pattern in converter dephosphorization blowing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for deciding an oxygen feeding flow rate pattern in converter dephosphorization blowing, with which an oxygen feeding quantity is dynamically controlled in accordance with the operating conditions during blowing without fixing an oxygen feeding flow rate pattern, and concentration of phosphorous in a molten steel at the end point of converter blowing is made to accurately hit the target value in a maintenance free state. <P>SOLUTION: Before the start of converter blowing, from molten iron conditions, blowing conditions and target conditions, a vector indicating the characteristics of the charge is obtained. The similar vector similar to the charge is selected from the past actual result database. an approximate model obtaining the optimum oxygen feeding flow rate is created. The optimum oxygen feeding flow rate patter in the charge is calculated using the created approximate model, and the optimum oxygen feeding flow rate pattern is decided as the oxygen feeding flow rate pattern in the charge. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for determining an acid feed amount pattern in converter dephosphorization blowing.

“Charging” one process from supplying main raw materials and auxiliary raw materials to blowing equipment, spraying oxygen, and outputting steel with the desired composition and temperature at the end of blowing (end point). ".

  The composition and temperature of pig iron and scrap supplied to the blow smelting equipment vary from charge to charge. Therefore, in order to produce the desired steel over the entire charge, it is necessary to implement optimum blowing control for each charge. There is.

  Pig iron contains various components, and phosphorus (phosphorus, P), which is the subject of the present invention, may be removed alone or may be removed together with other components. In blowing operation, it is an important issue to appropriately control the phosphorus concentration (end point P concentration) at the end of blowing (converter end point control).

  Until now, in dephosphorization blowing in converters, there are methods to calculate the required oxygen amount by static material balance calculation, and to estimate and control the amount of FeO in molten steel correlated with de-P from exhaust gas information. Proposed. The operating method is determined by selecting an empirically semi-immobilized acid feed pattern from the hot metal conditions before blowing and maintaining it.

Further, Patent Document 1 proposes a database model method in which similar results are extracted from past results in a decarburization furnace and a model is created by regression calculation each time.
JP 2006-233324 A

However, the method of calculating the amount of oxygen by static material balance calculation and the method disclosed in Patent Document 1 cannot sufficiently reflect operational fluctuations and changes with time, and have the following problems.
Since a fixed pattern is used, the amount of acid sent cannot be controlled dynamically depending on the operating state during blowing. In addition, it is necessary to maintain the pattern following the change with time, and if it is not sufficient, the optimum operation cannot be performed.

  The present invention has been made in view of such a problem, and dynamically controls the amount of acid fed according to the operating state during blowing without fixing the acid flow rate pattern, and is the maintenance-free converter blowing end point. It is an object of the present invention to provide a method for determining an acid flow rate pattern of converter dephosphorization blowing that can accurately target the phosphorus concentration in molten steel to a target value.

  The invention according to claim 1 of the present invention is similar to the charge from the past performance database, obtaining the vector representing the characteristics of the charge from the hot metal condition, the blowing condition, and the target condition before the start of the converter blowing. A similar vector is extracted, an approximate model for obtaining the optimal oxygen delivery flow rate is created based on the extracted similar vector, and an optimum oxygen delivery flow rate pattern for the charge is calculated using the created approximate model. This is a method for determining an acid flow rate pattern for converter dephosphorization blowing, wherein the flow rate is determined to be an acid flow rate pattern for the charge.

  The invention according to claim 2 of the present invention estimates the carbon concentration in the molten steel, the oxygen concentration in the molten steel, the phosphorus concentration in the molten steel, and the molten steel temperature based on the exhaust gas information during the dephosphorization blowing of the converter. Then, the vector representing the characteristics of the charge is obtained, a similar vector similar to the charge is extracted from the past performance database, and an approximate model for obtaining the optimal oxygen flow rate is created based on the extracted similar vector, and the created approximate model Is used to calculate the optimum acid flow rate pattern of the charge and to change the acid flow rate pattern of the charge after the calculation timing with the optimum acid flow rate pattern. This is a flow rate pattern determination method.

  Further, the invention according to claim 3 of the present invention is the method of determining the oxygen flow rate pattern of converter dephosphorization blowing according to claim 1 or 2, wherein the similar vector is extracted in the method of extracting the similar vector and the past performance blowing. A method for determining an acid flow rate pattern for converter dephosphorization blowing, wherein a similar vector is extracted based on a norm of deviation from a smelting vector.

  The invention according to claim 4 of the present invention is the method for determining an acid flow rate pattern of converter dephosphorization blowing according to any one of claims 1 to 3, wherein the approximation model is a regression of the similar vector. This is a method for determining an acid flow rate pattern of converter dephosphorization blowing, characterized in that it is created as an equation.

  The invention according to claim 5 of the present invention is the method for determining the flow rate of acid flow for converter dephosphorization blowing according to any one of claims 1 to 3, wherein the approximate model is used for each stage of blowing. This is a method for determining an acid feed flow rate pattern of converter dephosphorization blowing, characterized in that it is created as a sum of loads corresponding to the distance between the charge of the actual acid feed performance and a similar charge.

  Furthermore, the invention according to claim 6 of the present invention is configured to send an acid flow rate pattern determined using the method for determining the oxygen feed flow rate pattern of converter dephosphorization blowing according to any one of claims 1 to 5. It is a converter blowing end point control method characterized by controlling the acid flow rate to obtain a desired composition and temperature at the end of blowing.

  Since the present invention is configured as described above, the dynamic control model can be applied based on the exhaust gas information, so that the phosphorus concentration in the molten steel at the end of the converter blowing can be accurately targeted at the target value. It becomes possible. Further, the maintenance of the fixed pattern, which has been performed manually by the user, becomes unnecessary by updating the constructed database each time, and the optimum state can be maintained. As a result, not only the product quality and the iron yield are improved, but also a ripple effect such as a life extension effect of the converter refractory and an inability to reduce secondary refining is obtained, and an industrially beneficial effect is brought about.

  Hereinafter, the present invention will be specifically described with reference to the drawings. FIG. 1 is a block diagram showing a processing procedure 1 of a method for determining an acid flow rate pattern of converter dephosphorization blowing according to the present invention. This processing procedure 1 shows a processing procedure before the start of blowing, and will be described below with reference to this block diagram.

Step01: Define blowing condition vector (hot metal condition)
From new blowing conditions such as hot metal conditions, a new blowing condition vector Va is defined as in the following equation (1).

_{Va = (x 1, x 2} , x 3, x 4, x 5, x 6, x 7, x 8, ..., x n) ····· (1)
However, since the charge to be newly implemented is before blowing, there is no information at the end point, so the target value or the like is input to the end point actual temperature x ₆ , end point C concentration x ₇ and end point P concentration x ₈ . Further, the actual value x ₁ for each item of 1~n in charge of implementing the _{new, x 2, x 3, x} 4, x 5, x 6, x 7, x 8, ..., x n , the operator In some cases, it may be given by a host computer.

Step02: blowing conditions results in the charge record which is stored in the vector generating blowing record database of past results _{[x 1, x 2, x} 3, x 4, x 5, x 6, x 7, x 8, ..., x _n ] (for example, blowing conditions, actual results of acid feeding in each stage of blowing, accuracy of accuracy after blowing, etc.) are defined as actual blowing vector Vb as shown in equation (2).
_{Vb = (x 1, x 2} , x 3, x 4, x 5, x 6, x 7, x 8, ..., x n) ····· (2)

Following this, the actual values x _i (i = 1, 2,..., N) of the items 1 to n stored in the blowing performance database are averaged over all charges, the average value u _i and the standard Deviation σ _i is calculated. Next, the value x _i (i = 1, 2,..., N) of each item in the actual blowing conditions in each charge is normalized. The value x _ib of each item of the normalized vector is calculated by the following equation (3).
x _ib = (x _i −u _i ) / σ _i (3)

Next, the actual blown normalized vector Vbo shown in the equation (4) in which each item value x _i of the actual blown vector Vb for each charge is replaced with the normalized value x _ib is defined.
Vbo = (x _1b , x _2b , x _3b , x _4b , x _5b , x _6b , x _7b , x _8b ,..., X _nb ) (4)

Step03: The charge vectors created yet, under each item value x _^'i of the novel blowing vector Va of the charge, using the mean value and standard deviation were calculated from the values of blowing results database described above expression (5 ) To normalize.
x _ia = (x ^′ _i −u _i ) / σ _i (5)
Then, by replacing with each normalized value, a new blowing normalization vector Vao is defined as in equation (6).
Vao = (x _1a , x _2a , x _3a , x _4a , x _5a , x _6a , x _7a , x _8a ,..., X _na ) (6)

Step 04: Extract similar results Next, each deviation vector ΔVab between this new blowing normalization vector Vao and each actual blowing normalization vector Vbo is set as shown in equation (7).
ΔVab = Vao−Vbo (7)

A norm | ΔVab | is calculated as a quantitative evaluation criterion of the degree of similarity between the vectors Vao and Vbo. The norm calculation method is shown in the following equation (8).
| ΔVab | = [w ₁ (x _1a −x _1b ) ² + w ₂ (x _2a −x _2b ) ² +... + W _n (x _na −x _nb ) ² ] ^1/2 ... (8)
_{Here, w 1, w 2, ...} , w n is a weighting factor for each item of blowing conditions. In addition, although the example of the norm showing the distance between the charge and the similar charge is shown here as a quantitative evaluation standard of the similarity, the present invention is not limited to this, and other evaluation standards are used. Also good.

  Charges corresponding to k (predetermined) norms | ΔVab | are selected from the smaller ones of the calculated norms | ΔVab |, and a vector of the selected similar charges is read.

Step 05: Calculate the optimum oxygen delivery flow rate pattern Using the similar charge vector, create an approximate model for obtaining the optimum delivery oxygen flow rate Qs. The approximate model is, for example, the regression equation (9) shown below. Here, the explanatory variable is each item of the vector, or c ₀ , c ₁ , c ₂ , c ₃ , c ₄ , c ₆ , c ₇ , c ₈ ,..., C _n are coefficients and are selected The actual charge data is adjusted so that the estimation accuracy is high.
Qs = c ₀ + c ₁ x ₁ + c ₂ x ₂ + c ₃ x ₃ + c ₄ x ₄ + c ₆ x ₆ + c ₇ x ₇ + c ₈ x ₈ +… + c _n x _n (9)

By substituting each item of the new blowing condition vector into the created approximate model, the optimum oxygen delivery flow rate pattern is calculated.
In addition, the approximate model for obtaining the optimum acid delivery flow rate Qs can be a load sum corresponding to the distance between the charge and the similar charge of the actual acid delivery performance in each stage of blowing. FIG. 3 is a diagram for explaining the calculation of the optimum acid flow rate pattern before the start of blowing. The optimal oxygen delivery flow rate pattern is obtained by calculating the load sum corresponding to the similarity of the oxygen delivery flow rate patterns of three similar charges.

Step 06: Determining the acid delivery flow rate pattern The optimum acid delivery flow rate pattern obtained above is determined as the acid delivery flow rate pattern for the charge.

  FIG. 2 is a block diagram showing the processing procedure 2 of the method for determining the acid flow rate pattern for converter dephosphorization blowing according to the present invention. This processing procedure 2 shows the processing procedure during blowing, and is different from the processing procedure 1 of FIG. 1 in that Step 01 and Step 06, and Step 01 to Step 06 are repeated at a constant cycle. Description of the same processing is omitted, and only different processing is described.

Step01: Define blowing condition vector (estimated component in molten steel from exhaust gas information)
A blowing condition vector is defined using on-line estimation results of in-furnace components, temperature, FeO amount, and the like based on exhaust gas information measured during blowing.

Step 06: Change the oxygen delivery flow rate pattern FIG. 4 is a diagram for explaining the calculation of the optimum oxygen delivery flow rate pattern during blowing. If the extracted similar vector is different from the previously extracted similar vector based on the exhaust gas information measured during blowing, the optimum flow rate of oxygen delivery calculated was calculated last time (if this is the first time after the start of blowing, It is different from the optimal oxygen delivery flow rate pattern. FIG. 4 also shows that the similar charge 3 is different from the previous time, and the optimum oxygen delivery flow rate pattern different from the previous time is obtained as the latest pattern. Therefore, the oxygen delivery flow rate pattern after the calculated timing is changed.

  Then, Step 01 to Step 06 are repeated at regular intervals or irregularly by obtaining exhaust gas information. By finely setting the calculation cycle, it is possible to sequentially obtain and update the optimum amount of acid sent from the operation with the fixed pattern so far.

  Then, the converter blowing end point control is performed under the management of the operation procedure so that the acid flow rate pattern determined in the processing procedure 1 and the processing procedure 2 is obtained.

  As described above, since the dynamic control model can be applied based on the exhaust gas information, it is possible to accurately target the phosphorus concentration in the molten steel at the end point of the converter blowing to the target value. Further, the maintenance of the fixed pattern, which has been performed manually by the user, becomes unnecessary by updating the constructed database each time, and the optimum state can be maintained. As a result, not only the product quality and the iron yield are improved, but also the ripple effect such as the life extension effect of the converter refractory and the inability to reduce the secondary refining is obtained, and the industrially excellent effect is achieved.

It is a block diagram which shows the process procedure 1 of the acid feeding flow rate pattern determination method of the converter dephosphorization blowing which concerns on this invention. It is a block diagram which shows the process procedure 2 of the acid sending flow rate pattern determination method of the converter dephosphorization blowing which concerns on this invention. It is a figure explaining the optimal acid-feed flow pattern calculation before blowing. It is a figure explaining the optimal oxygen delivery flow rate pattern calculation during blowing.

Claims (6)

Prior to the start of converter blowing, the vector representing the characteristics of the charge is obtained from the hot metal conditions, blowing conditions, and target conditions, a similar vector similar to the charge is extracted from the past performance database, and the extracted similar vector is obtained. Create an approximate model for determining the optimal oxygen delivery flow rate based on the calculated approximate delivery rate flow pattern for the charge using the approximate model and determine the optimum acid delivery flow rate pattern as the charge delivery flow rate pattern for the charge. A method for determining an acid flow rate pattern of converter dephosphorization blowing. During converter dephosphorization, the carbon concentration in the molten steel, the oxygen concentration in the molten steel, the phosphorus concentration in the molten steel, and the molten steel temperature are estimated based on the exhaust gas information, and the vector representing the characteristics of the charge is obtained. Then, a similar vector similar to the charge is extracted from the past performance database, an approximate model for obtaining the optimum oxygen delivery flow rate based on the extracted similar vector is created, and the optimum acid delivery flow rate pattern of the charge is calculated using the created approximate model. A method for determining an acid flow rate pattern for converter dephosphorization blowing, wherein the oxygen flow rate pattern of the charge after the calculation timing is changed using the optimum oxygen flow rate flow pattern. In the method for determining the acid flow rate pattern of the converter dephosphorization blowing according to claim 1 or 2,
In extracting the similar vector,
A method for determining an oxygen flow rate pattern for converter dephosphorization blowing, wherein a similar vector is extracted based on a norm of a deviation between the vector and a past performance blowing vector. In the method for determining the acid flow rate pattern of converter dephosphorization blowing according to any one of claims 1 to 3,
The approximate model is created as a regression equation of the similar vector, and a method for determining an acid flow rate pattern for converter dephosphorization blowing. In the method for determining the acid flow rate pattern of converter dephosphorization blowing according to any one of claims 1 to 3,
A method for determining an acid flow rate pattern for converter dephosphorization blowing, wherein the approximate model is created as a load sum corresponding to a distance between the charge and the similar charge of the actual acid transfer performance in each stage of blowing. The oxygen feed flow rate is controlled by the acid feed flow rate pattern determined using the method for determining the oxygen feed flow rate pattern of converter dephosphorization blowing according to any one of claims 1 to 5, and at the end of blowing. A converter blowing end point control method characterized by having a desired composition and temperature.

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