JP5962070B2 - Control method and control device for hot metal blowing process - Google Patents

Description

  The present invention relates to a control method and a control device for hot metal blowing process in which the concentration of phosphorus in hot metal is controlled by adding powdered lime and massive lime to hot metal during the hot metal blowing process. .

  In the hot metal blowing process using a converter, the concentration of phosphorus in the hot metal is reduced by adding massive lime as a dephosphorizing agent to the hot metal. In such a blowing process, in order to promote the dephosphorization reaction, the massive lime needs to hatch (melt). However, since the hot metal temperature during the dephosphorization reaction is in a low temperature range of about 1300 to 1400 ° C., the massive lime is not easily hatched in the hot metal. For this reason, in the conventional blowing process, fluorite was added to the molten iron as a hatching accelerator in order to rapidly hatch the massive lime. In recent years, however, the use of solvents containing fluorine such as fluorite has been restricted. For this reason, there has been proposed a method capable of promoting lime hatching without using fluorite. Specifically, Patent Document 1 describes a method of promoting the hatching of lime by replacing a part of the massive lime required for hot metal dephosphorization with powdered lime that is easy to hatch. ing.

JP 2009-114494 A

  By the way, since powdery lime is manufactured by pulverizing massive lime, it is more expensive than massive lime. Moreover, since powdery lime is gas-transported via piping, such as a lance, the quantity which can be projected on hot metal has restrictions. From such a background, in the conventional blowing process in which massive lime and powdered lime are added, while adding a predetermined amount of powdered lime, massive lime so that hot metal dephosphorization is performed reliably. Was thrown in. However, when extra lump of lime is added, the amount of slag produced in the blowing process increases. In addition, when extra lump of lime is added, the hot metal temperature decreases, so that many heat sources are required to maintain the hot metal temperature at a temperature suitable for the dephosphorization reaction. For this reason, provision of the technique which evaluates the dephosphorization effect by powdery lime and can control appropriately the addition amount of block-like lime based on the evaluation result was anticipated.

  The present invention has been made in view of the above problems, and its purpose is to evaluate the dephosphorization effect of powdered lime, and based on the evaluation result, the hot metal that can appropriately control the addition amount of massive lime. It is providing the control method and control apparatus of a blowing process.

  In order to solve the above problems and achieve the object, the method for controlling the hot metal blowing process according to the present invention adds powdered lime and massive lime to the hot metal during the hot metal blowing process. A control method of hot metal blowing process for controlling the concentration of phosphorus in hot metal, using index data representing the dephosphorization effect by the powdery lime using the past data of past blowing process for each actual data A set value calculating step for calculating and determining a set value of the index value for each blowing condition from the index value of each performance data using the t test, and the index corresponding to the blowing condition in the blowing process to be performed from now on Based on the set value of the value, based on the prediction step of predicting the dephosphorization effect due to the powdery lime in the blowing process to be performed from now on, and the dephosphorization effect due to the powdery lime predicted in the prediction step Lump to be poured into the hot metal Characterized by comprising a control step of controlling the amount of lime, the.

  The control method of the hot metal blowing process according to the present invention is the above-described invention, wherein the past result data of the blowing process includes the past data and the lump of the blowing process using both powdery lime and lump lime. It includes the performance data of the blowing process using only lime.

  The control method of the hot metal blowing process according to the present invention is the above invention, wherein the blowing condition is at least one of phosphorus concentration of hot metal, hot metal temperature, hot metal silicon concentration, basicity of slag, and blowing temperature. It is characterized by being one.

  In order to solve the above problems and achieve the object, the control device for hot metal blowing process according to the present invention adds powdered lime and massive lime to the hot metal during the hot metal blowing process. A control device for a hot metal blowing process for controlling the phosphorus concentration in the hot metal, and for each of the performance data, an index value representing the dephosphorization effect by the powdered lime using the past data of the past blowing process. A set value calculating means for determining a set value of an index value for each blowing condition from an index value of each performance data using t-test, and the index corresponding to the blowing condition in the blowing process to be performed from now on Based on the set value of the value, based on the dephosphorization effect by the powdery lime predicted by the prediction step, predicting means for predicting the dephosphorization effect by the powdery lime in the blowing process to be performed from now Of massive lime to be put into the hot metal Characterized in that it comprises a control means for controlling the.

  According to the control method and control device for hot metal blowing process according to the present invention, the dephosphorization effect by powdery lime can be evaluated, and the amount of lump lime added can be appropriately controlled based on the evaluation result.

FIG. 1 is a schematic diagram showing a configuration example of a blowing process facility to which a blowing control system according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing a configuration of a blowing control system according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of blowing performance data stored in the blowing performance database shown in FIG. FIG. 4 is a diagram showing an example of lime projection effect data stored in the lime projection effect database shown in FIG. FIG. 5 is a flowchart showing the flow of lime projection effect calculation processing according to an embodiment of the present invention. FIG. 6 is a flowchart showing the flow of the blowing control process according to an embodiment of the present invention.

  Hereinafter, the configuration and operation of a blowing control system according to an embodiment of the present invention will be described with reference to the drawings.

[Configuration of blow smelting treatment equipment]
First, with reference to FIG. 1, the structure of the blowing process equipment to which the blowing control system which is one Embodiment of this invention is applied is demonstrated.

FIG. 1 is a schematic diagram showing a configuration example of a blowing process facility to which a blowing control system according to an embodiment of the present invention is applied. As shown in FIG. 1, a blowing process equipment 1 to which a blowing control system according to an embodiment of the present invention is applied includes a hot metal ladle 3 that accommodates a hot metal 2 inside, and an inside of the hot metal ladle 3 in the vertical direction. And an upper blowing lance 4 that is movable. The top blowing lance 4 sprays oxygen (O ₂ ) gas onto the hot metal 2 accommodated in the hot metal ladle 3 and also supplies a solid oxygen source 7 accommodated in the storage tank 6 using oxygen (O ₂ ) gas as a carrier gas. Is sprayed onto the hot metal 2. Moreover, the top blowing lance 4 has a multi-pipe structure and also has a cooling water pipe (not shown) for water supply and drainage.

  The blowing process facility 1 further includes a hopper 10, a transport device 11, and a chute 12. The hopper 10 accommodates massive lime (bulk lime) 13 inside, and cuts the massive lime 13 to the conveying device 11 side. The conveying apparatus 11 conveys the lump lime cut out from the hopper 10 to the chute 12 side. The chute 12 throws the lump lime 13 transported by the transport device 11 into the hot metal 2 in the hot metal pan 3.

[Configuration of blowing control system]
Next, with reference to FIG. 2 thru | or FIG. 4, the structure of the blowing control system which is one Embodiment of this invention is demonstrated. FIG. 2 is a block diagram showing a configuration of a blowing control system according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of blowing performance data stored in the blowing performance database shown in FIG. FIG. 4 is a diagram showing an example of lime projection effect data stored in the lime projection effect database shown in FIG.

  As shown in FIG. 2, the blowing control system 100 which is one Embodiment of this invention is equipped with the blowing performance database 101, the blowing control apparatus 102, and the lime projection effect database 103. As shown in FIG. Blowing performance database 101 stores blowing condition data regarding past charges as blowing performance data. More specifically, as shown in FIG. 3, the blowing performance database 101 includes unique identification information (charge ID) given for each past charge and the amount of powdered lime added during the blowing process. (Powdered lime input), Amount of lump added during blowing process (Lumped lime input), Phosphorus concentration in molten steel after blowing process, Phosphorus concentration in hot metal before blowing process, Blowing The information relating the hot metal temperature before the treatment, the silicon concentration in the hot metal before the blowing process, the basicity of the slag, and the blowing temperature is stored as the blowing result data. The blowing performance data stored in the blowing performance database 101 is updated as needed by a host computer such as a process computer. In addition, a charge means the process unit when performing the hot metal blowing process, and is equivalent to the hot metal 2 for 3 cups of the hot metal ladle shown in FIG.

  The blowing control device 102 is configured by an information processing device such as a personal computer or a workstation. The blowing control device 102 functions as a lime projection effect calculation unit 102a and a lime supply amount control unit 102b when an arithmetic processing device such as a CPU inside the information processing device executes a computer program. The functions of these units will be described later. The lime projection effect calculation unit 102a functions as a set value calculation unit and a prediction unit according to the present invention, and the lime supply amount control unit 102b functions as a control unit according to the present invention.

The blowing control device 102 evaluates the dephosphorization ability of the powdered lime for each blowing condition, and stores the evaluation result in the lime projection effect database 103 as lime projection effect data. Specifically, as shown in FIG. 4, the lime projection effect database 103 includes the ratio of the dephosphorization effect of the powdered lime to the dephosphorization effect of the lump of molten iron and the lump lime at each temperature (the ratio in the example shown in FIG. 4). R _{1 to} R ₆ ) are stored as lime projection effect data. And the blowing control apparatus 102 refers to the lime projection effect data stored in the lime projection effect database 103, and controls the addition amount of lump lime in the blowing process equipment 1 according to blowing conditions.

  The blowing control apparatus system 100 having such a configuration controls the amount of lump lime added in the blowing process by executing the following lime projection effect calculation process and blowing control process. Hereinafter, with reference to the flowcharts shown in FIGS. 5 and 6, the operation of the blowing control system 100 when executing the lime projection effect calculation process and the blowing control process will be described.

[Lime projection effect calculation processing]
First, with reference to FIG. 5, operation | movement of the blowing control system 100 at the time of performing a lime projection effect calculation process is demonstrated. FIG. 5 is a flowchart showing the flow of lime projection effect calculation processing according to an embodiment of the present invention. The flowchart shown in FIG. 5 starts at the timing when the blowing performance data in the blowing performance database 101 is updated, and the lime projection effect calculation processing proceeds to the processing of step S1.

In the process of step S1, the lime projecting effect calculation unit 102a uses the blasting result database 101 for the charge using both powdered lime and lump lime, and an index of the dephosphorization effect of lime combining the powdered lime and lump lime. The value α _mixture (β) and the proportion β of the powdered lime in the total input amount of lime are calculated. Specifically, assuming that the ratio of the dephosphorization effect by powdered lime to the dephosphorization effect by bulk lime is R, the amount b (ton) of bulk lime to be charged when powdered lime is projected a (ton) is as follows: It can be calculated from the mathematical formula (1) shown. On the other hand, when the index value α _powder and α _lump of the dephosphorization effect of powdered lime and lump lime are respectively formulated by the following formulas (2) and (3), the ratio R is expressed by the following formula (4). Can be represented. Moreover, the hot metal phosphorus concentration and the molten steel phosphorus concentration in the formulas (2) and (3) indicate the phosphorus concentration before and after the dephosphorization treatment, respectively.

Therefore, the ratio R is calculated from the formulas (2) to (4) using the blow performance data of the charge using only the powdered lime and the charge using only the lump lime, and the calculated ratio R is expressed by the formula (1). ) Can be calculated to calculate the amount b (ton) of lump lime to be charged when powdered lime is projected a (ton). However, in actual operation, there are cases where the blowing process cannot be performed using only powdered lime due to restrictions on equipment and operation, in which case the index value α _powder of the dephosphorization effect of powdered lime may be calculated. As a result, the ratio R cannot be calculated.

Therefore, the lime projection effect calculation unit 102a combines the powdered lime and the lump lime from the charge blowing performance data using the powdered lime and the lump lime using the following formulas (5) and (6). The index value α _mixture (β) of the dephosphorization effect of lime and the proportion β of powdered lime in the total amount of lime input are calculated. In addition, the ratio (beta) of the powdered lime which occupies for the total input amount of lime can be expressed as the following formula (7) using the index value α _powder and α _mass of the dephosphorization effect of powdered lime and lump lime. Thereby, the process of step S1 is completed and a lime projection effect calculation process progresses to the process of step S2.

In the process of step S2, the lime projection effect calculation unit 102a reads charge blowing result data using only lump lime from the blowing record database 101, and the lump input amount in the read blowing result data, By substituting the molten iron phosphorus concentration and molten steel phosphorus concentration data into the formula (3), the index value α _lump of the dephosphorization effect of lump lime is calculated. Thereby, the process of step S2 is completed and the lime projection effect calculation process proceeds to the process of step S3.

In the process of step S3, the lime projection effect calculation unit 102a sets the index value α _mixture (β) of the dephosphorization effect of lime, which is a combination of the powdered lime and the lump lime calculated by the process of step S1, and the total lime input amount. by substituting the index value α _mass dephosphorization effect mass lime calculated by the processing of the ratio β and the step S2 flour lime in equation (7) occupying the index value α _powder dephosphorization effect powder lime Approximate calculation. Thereby, the process of step S3 is completed and the lime projection effect calculation process proceeds to the process of step S4.

In the process of step S4, lime projection effect calculating unit 102a is an indication of dephosphorization effect of the calculated powder lime by treatment of the index value α _masses and step S3 of dephosphorization effect mass lime calculated by step S2 By substituting the value α _powder into Equation (4), the ratio R of the dephosphorization effect by the powdered lime to the dephosphorization effect by the lump lime is calculated as an index value R representing the effect of the lime projection. Thereby, the process of step S4 is completed and the lime projection effect calculation process proceeds to the process of step S5.

In the process of step S5, the lime projection effect calculation unit 102a calculates a value R representing the effect of lime projection for all charge blowing performance data using powdered lime stored in the blowing performance database 101. It is determined whether or not. As for the charge using only flour lime, it is possible to directly calculate the index value α _powder dephosphorization effect powder lime using Equation (2). As a result of the determination, when the value R is not calculated for all charge blowing performance data, the lime projection effect calculation unit 102a returns the lime projection effect calculation process to the process of step S1. On the other hand, when the value R is calculated for all charge blowing performance data, the lime projection effect calculation unit 102a advances the lime projection effect calculation process to the process of step S6.

  In the process of step S6, the lime projection effect calculation part 102a determines the value R which should be actually set for every blowing condition from the some value R calculated by the process of step S4. That is, since the value R calculated by the above processing includes an error, the value R cannot be used as a set value as it is. Therefore, the lime projection effect calculation unit 102a determines a value R to be actually set from a plurality of values R for each blowing condition using a t test. The t test is a method for testing an average value when the population variance is unknown, and is a method used particularly when the number of samples is small. By using the t-test, the set value of the value R can be determined with an arbitrary reliability even with respect to the blowing conditions with variations and a small number of actual samples.

Specifically, the lime projection effect calculation unit 102a determines the set value of the value R from the plurality of values R by performing the following calculation. Assuming that the actual values of the N values R calculated by the process of step S4 are x _i (i = 1, 2,..., N), the sample average x _av and the standard deviation s are expressed by the following equation (8). , (9), and the t statistic at this time is expressed as the following formula (10). Note that the parameter μ in the equation (10) indicates a population average.

  The t statistic shown in Equation (10) follows a distribution called t distribution with degrees of freedom (N−1). Therefore, first, the lime projection effect calculating unit 102a calculates the t statistic assuming the population average μ, and how much probability the actual value of the value R can occur based on the calculated t statistic. To evaluate. When the target reliability is, for example, 95% (error rate 0.05), the lime projection effect calculation unit 102a is a value that occurs only with a probability that the actual value of the value R is less than 5%. It is determined that the assumed population mean μ is incorrect.

  In general, this determination is performed using a t-test table shown in Table 1 below. That is, the lime projection effect calculation unit 102a rejects the assumed mother average μ if the calculated t statistic is larger than the value shown in Table 1 below, and adopts the assumed mother average μ if it is smaller. In this way, the lime projection effect calculation unit 102a evaluates the validity of the population mean μ, and the largest value R in the range of the reliable population mean μ (this value is referred to as the upper limit of the confidence interval) is the value R. Determine the setting value. And the lime projection effect calculation part 102a stores the setting value of the value R for every blowing condition in the lime projection effect database 103 as lime projection effect data. Thereby, the process of step S6 is completed and a series of lime projection effect calculation processes are complete | finished.

(Blowing control process)
Next, the operation of the blowing control system 100 when executing the blowing control process will be described with reference to FIG. FIG. 6 is a flowchart showing the flow of the blowing control process according to an embodiment of the present invention. The flowchart shown in FIG. 6 starts at the timing of setting the amount of lump lime added, and the blowing control process proceeds to the process of step S11.

  In the process of step S11, the lime supply amount control unit 102b acquires blowing condition data such as hot metal phosphorus concentration and temperature and the amount of powdered lime added from a host computer such as a process computer. Thereby, the process of step S11 is completed and a blowing control process progresses to the process of step S12.

  In the process of step S12, the lime supply amount control unit 102b acquires the set value of the value R corresponding to the blowing condition data acquired by the process of step S11 from the lime projection effect database 103. Thereby, the process of step S12 is completed and a blowing control process progresses to the process of step S13.

  In the process of step S13, the lime supply amount control unit 102b substitutes the data of the added amount of powdered lime acquired by the process of step S11 and the set value of the value R acquired by the process of step S12 into the formula (1). Thus, the amount of lump lime added is calculated. Thereby, the process of step S13 is completed and a blowing control process progresses to the process of step S14.

  In the process of step S14, the lime supply amount control unit 102b blows and treats the addition amount of powdered lime acquired by the process of step S11 and the addition amount of lump calculus calculated by the process of step S13. 1 is controlled. Thereby, the process of step S14 is completed and a series of blowing control processes are complete | finished.

  As is clear from the above description, in the blowing control system 100 according to an embodiment of the present invention, the blowing control device 102 uses the past performance data of the blowing process to improve the dephosphorization effect by powdered lime. The index value R is calculated for each performance data, and the t-test is used to determine the setting value of the index value R for each blowing condition from the index value R of each performance data, and the blowing condition in the blowing process to be executed from now on Based on the setting value of the index value R corresponding to, the amount of lump lime that is predicted in the dephosphorization effect by powdered lime in the blowing process to be performed from now on and is put into the hot metal based on the predicted dephosphorization effect by powdered lime To control. That is, the blowing control apparatus 102 evaluates the dephosphorization effect by the powdered lime based on the blowing conditions, and controls the amount of lump lime introduced into the molten iron based on the evaluation result. Thereby, the addition amount of lump lime can be controlled appropriately, and the heat source for maintaining the production amount of the slag and the hot metal temperature in the blowing process at a temperature suitable for the dephosphorization reaction can be reduced.

〔Example〕
Table 2 below shows the number of samples, the average value, and the standard deviation of the phosphorus concentration of hot metal and the value R for each temperature calculated by the method of the present invention. Table 3 below shows the result of applying the t test to the value R shown in Table 2.

In general, the smaller the value R representing the effect of lime projection, the greater the total amount of lump lime that should be input. When the amount of lump lime to be charged in the actual operation is unknown, the operator performs operation safely by adding a large amount of lump lime and performing extra dephosphorization. That is, in the conventional blowing process which does not evaluate by changing the effect of powdered lime according to the blowing conditions, the minimum value (1.41) of the value R shown in Table 3 is applied to all blowing conditions. On the other hand, according to the method of the present invention, the effect of lime projection can be changed according to the blowing conditions, and blowing larger than the minimum value R can be performed. For example, when the hot metal phosphorus concentration is 120 (10 ⁻³ %) or more and the hot metal temperature is 1215 ° C. or less, the value R is set to 1.49 shown in Table 3 in the method of the present invention. . Accordingly, when 4 (tons) of powdered lime is projected on one charge, the amount of lump lime used is reduced by 0.32 (= 4 × (1.49-1.41)) (ton) per charge. be able to. As a result, the heat source for maintaining the amount of slag produced and the hot metal temperature in the blowing process at a temperature suitable for the dephosphorization reaction can be reduced.

  Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the description and the drawings that form a part of the disclosure of the present invention according to this embodiment. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Blowing treatment equipment 2 Hot metal 3 Hot metal ladle 4 Top blowing lance 6 Storage tank 7 Solid oxygen source 10 Hopper 11 Conveying device 12 Chute 13 Lumped lime (lump lime)
DESCRIPTION OF SYMBOLS 100 Blowing control system 101 Blowing performance database 102 Blowing control apparatus 102a Lime projection effect calculation part 102b Lime supply amount control part 103 Lime projection effect database

Claims (4)

A method for controlling a hot metal blowing process in which the phosphorus concentration in hot metal is controlled by adding powdered lime and massive lime to the hot metal during the hot metal blowing process,
An index value representing the dephosphorization effect by the powdery lime is calculated for each of the actual data using the past data of the blowing process, and the blowing condition is determined from the index value of each of the actual data using the t test. A set value calculation step for determining a set value of each index value;
Based on the setting value of the index value corresponding to the blowing conditions in the blowing process to be executed from now on, a prediction step for predicting the dephosphorization effect by the powdery lime in the blowing process to be executed from now on,
A control step of controlling the amount of massive lime to be introduced into the hot metal based on the dephosphorization effect by the powdery lime predicted in the prediction step;
A control method of hot metal blowing process characterized by including.   The past performance data of the blowing process includes the past data of the blowing process using both powdered lime and the massive lime and the past data of the blowing process using only the massive lime. The method for controlling the hot metal blowing process according to claim 1, wherein the hot metal blowing process is performed.   3. The blowing method according to claim 1, wherein the blowing condition is at least one of hot metal phosphorus concentration, hot metal temperature, hot metal silicon concentration, slag basicity, and blowing temperature. Control method of hot metal blowing process. A control device for hot metal blowing process that controls the phosphorus concentration in hot metal by adding powdered lime and lump lime to hot metal during the hot metal blowing process,
An index value representing the dephosphorization effect by the powdery lime is calculated for each of the actual data using the past data of the blowing process, and the blowing condition is determined from the index value of each of the actual data using the t test. A setting value calculating means for determining a setting value of each index value;
Prediction means for predicting the dephosphorization effect by the powdery lime in the blowing process to be performed based on the setting value of the index value corresponding to the blowing conditions in the blowing process to be performed from now on,
Control means for controlling the amount of massive lime to be introduced into the hot metal based on the dephosphorization effect by the powdery lime predicted by the prediction step;
An apparatus for controlling a hot metal blowing process.

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