Operation method of converter and blowing control system of converter

Abstract

Provided is a converter operation method for controlling the temperature of molten metal at the time of the mid-course sublance insertion within a range that enables the temperature and composition of the molten metal at the end of blowing to reach the target values through correction under dynamic control. In a converter operation method for controlling the temperature and composition of molten steel at the end of blowing to the target values using static control and dynamic control, during the oxygen blowing of hot metal, the estimated values of the molten metal temperature, i.e., the in-blowing temperature estimated value, and the estimated value of the carbon concentration in the molten metal, i.e., the in-blowing carbon concentration estimated value, are successively estimated (S-4). During a specified period (S-5) before the sublance is inserted, the difference (mid-course temperature difference) between the preset mid-course temperature target value and the predicted value of the molten metal temperature at the sublance insertion time, i.e., the mid-course temperature predicted value, is calculated (S-6). When the absolute value of the calculated mid-course temperature difference is greater than a preset threshold value, before the sublance is inserted, a cooling material or a heating material is added into the converter (S-8, S-10) to control the molten metal temperature at the sublance insertion time.

Description

Technical Field

[0001] The present invention relates to an operation method of a converter for producing molten steel from hot metal by blowing an oxidizing gas from a top-blown lance into the hot metal in the converter, and a blowing control system for the converter. Background Art

[0002] In a converter for producing molten steel from hot metal, decarburization refining of hot metal is performed by oxygen blowing (hereinafter also simply referred to as "blowing") from a top-blown lance to produce molten steel. In this converter operation, as a blowing control method for making the molten steel temperature and the molten steel component concentration at the end of oxygen blowing reach the target values, static control and dynamic control are performed. Among them, static control is the following control: Before the start of blowing, based on the information of the hot metal and iron chips used in this blowing, the supply oxygen amount required to make the molten steel temperature and the molten steel components at the end of stopping blowing reach the target values is calculated, and the amount of auxiliary raw materials to be input to make the molten steel temperature and the molten steel components at the end of stopping blowing reach the target values is calculated.

[0003] Dynamic control is the following control: Based on the information obtained by inserting a sublance (hereinafter also denoted as "midway sublance") into the converter during blowing, that is, the sublance measurement value (molten metal temperature, or both the molten metal temperature and the carbon concentration in the molten metal), the supplied oxygen amount and the input auxiliary raw materials are made appropriate, and the molten steel temperature and the molten steel components at the end of stopping blowing are adjusted to the target values. Conventionally, the sublance is inserted at the timing of supplying the oxygen amount obtained by subtracting a specified amount from the supply oxygen amount obtained by static control to obtain the sublance measurement value.

[0004] By static control, when the deviation between the sublance measurement value of the midway sublance and the target molten steel temperature and the target carbon concentration at the end of stopping blowing becomes large, it is difficult to perform correction under dynamic control. As a result, the molten steel temperature, the carbon concentration and / or the oxygen concentration in the molten steel at the end of stopping blowing deviate greatly from the target values.

[0005] When the molten steel temperature at the end of stopping blowing is higher than the target temperature, cooling materials are added to the furnace, the blowing time becomes longer, productivity deteriorates, and the melting loss of the lining refractory material of the converter becomes larger, increasing the repair cost of the lining refractory material. On the other hand, when the molten steel temperature at the end of stopping blowing is lower than the target temperature, blowing is restarted, and the temperature is increased by the combustion of iron (Fe) in the molten steel. Since blowing is restarted again, the oxygen content in the molten steel at the end of stopping blowing is higher than the target value, and the input amount of metallic aluminum (Al) for deoxidizing the molten steel increases, increasing the manufacturing cost. In this case, by restarting blowing, the carbon content in the molten steel at the end of stopping blowing usually becomes lower than the target value.

[0006] Therefore, a technology is required to make the molten steel temperature and the molten steel components (carbon concentration, oxygen concentration) at the end of stopping oxygen blowing reach the target values.

[0007] In order to make the molten steel temperature and composition reach the target values at the end of blowing using static control and dynamic control, it is necessary to control the measured values of the molten metal temperature and carbon concentration in the molten metal at the time of the mid-course sublance insertion within a range that can easily make the molten steel temperature and composition reach the target values at the end of blowing through correction under dynamic control.

[0008] In the past, as a method for determining the time of mid-course sublance insertion, for example, in Patent Document 1, the time required for dynamic control is determined based on blowing conditions, the amount of oxygen blown in during the determined dynamic control time is calculated, and the time when the amount of oxygen obtained by subtracting the calculated amount of oxygen from the amount of oxygen (predetermined supply amount) obtained by static control is blown in is determined as the time of mid-course sublance insertion.

[0009] In addition, in Patent Documents 2 and 3, the emission spectrum, exhaust gas flow rate, and exhaust gas component concentration observed from the mouth of the converter are measured, and the timing when the decarburization oxygen efficiency decreases is determined as the switching timing between static control and dynamic control, that is, the time of mid-course sublance insertion, by sequentially estimating the carbon concentration in the furnace.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: Japanese Patent Laid-Open No. 2007-327113

[0013] Patent Document 2: Japanese Patent Laid-Open No. 2020-105611

[0014] Patent Document 3: International Publication No. 2019 / 220800 Summary of the Invention

[0015] Problems to be Solved by the Invention

[0016] However, in the method disclosed in Patent Document 1, static control is used to determine the measurement timing of the mid-course sublance. When the blowing conditions change due to external disturbances, the measurement timing of the mid-course sublance also becomes inappropriate. As a result, problems such as the inability to ensure the time for dynamic control, or the need for time from the insertion of the mid-course sublance to the end of blowing, and a decrease in the accuracy of dynamic control may occur.

[0017] In addition, in Patent Documents 2 and 3, regardless of the change in blowing conditions, the insertion timing of the mid-course sublance is determined based on the calculated values sequentially calculated from the measured values. However, even if the mid-course sublance is inserted at the determined timing, the measured molten metal temperature and carbon concentration in the molten metal may not necessarily reach the range that can be corrected by subsequent dynamic control.

[0018] That is, Patent Documents 1 to 3 only determine the timing of inserting the lance during the process, and do not disclose the technical idea of controlling the molten metal temperature and the carbon concentration in the molten metal at the lance insertion time during the process within a range that can easily make the temperature and composition of the molten steel at the end of blowing reach the target values through correction under dynamic control.

[0019] The present invention has been completed in view of the above circumstances, and its object is to provide a method for operating a converter. In the converter operation method of controlling the temperature and composition of the molten steel at the end of blowing to target values using static control and dynamic control, through correction under dynamic control, the molten metal temperature at the lance insertion time during the process can be controlled within a range that can make the temperature and composition of the molten steel at the end of blowing reach the target values. In addition, a blowing control system for a converter for performing the converter operation method is provided.

[0020] Means for solving the problem

[0021] The gist of the present invention for solving the above problems is as follows.

[0022] [1] A method for operating a converter, in which, during blowing for decarburizing and refining hot metal by blowing an oxidizing gas into the hot metal in the converter, a lance is inserted into the furnace and a lance measurement value including at least the molten metal temperature in the furnace is actually measured. Based on the actually measured lance measurement value, the amount of oxygen to be supplied until the end of blowing and whether to insert a cooling material or a heating material and the insertion amount are determined, thereby controlling the temperature and component concentration of the molten steel at the end of blowing to target values. Among them,

[0023] The target value of the molten metal temperature at the lance insertion time, that is, the intermediate temperature target value, is determined, and the confirmation timing for confirming the difference between the intermediate temperature target value and the predicted intermediate temperature value, that is, the intermediate temperature difference, during blowing before the lance insertion time is determined. The predicted intermediate temperature value is the predicted value of the molten metal temperature at the lance insertion time.

[0024] Based on the operating conditions and measurement values of the converter obtained at the start and during blowing, the estimated value of the molten metal temperature at the blowing progress time, that is, the estimated temperature during blowing, and the estimated value of the carbon concentration in the molten metal, that is, the estimated carbon concentration during blowing, are successively estimated.

[0025] And when blowing progresses to the confirmation timing, the intermediate temperature difference is calculated based on the estimated temperature during blowing and the estimated carbon concentration during blowing.

[0026] When the absolute value of the calculated intermediate temperature difference is greater than a preset threshold value, during blowing after the confirmation timing and before inserting the lance, a cooling material or a heating material is inserted into the converter.

[0027] [2]According to the method for operating a converter described in [1] above, wherein the confirmation timing is determined based on the estimated value of the carbon concentration during blowing.

[0028] [3]According to the method for operating a converter described in [2] above, wherein the confirmation timing is determined within a range where the estimated value of the carbon concentration during blowing is 0.6 to 1.4% by mass.

[0029] [4]According to the method for operating a converter described in any one of [1] to [3] above, wherein the preset threshold value is a value selected from values of 10 °C or more.

[0030] [5]According to the method for operating a converter described in any one of [1] to [4] above, wherein when the absolute value of the temperature difference during the process is greater than the preset threshold value, the amount of the cooling material or the amount of the heating material charged during the blowing after the confirmation timing and before the sublance is inserted is determined based on one or more of the estimated value of the temperature during blowing, the target value of the molten steel temperature at the end of blowing, and the amount of quicklime charged into the converter during this blowing.

[0031] [6]According to the method for operating a converter described in any one of [1] to [5] above, wherein the measured values of the converter obtained at the start of blowing and during blowing include either or both of the measured values obtained by an exhaust gas flowmeter and an exhaust gas analyzer.

[0032] [7]According to the method for operating a converter described in any one of [1] to [6] above, wherein the measured values of the converter obtained at the start of blowing and during blowing are measured values related to the optical characteristics of the converter mouth portion during blowing, including the change rate of the emission intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.

[0033] [8]According to the method for operating a converter described in any one of [1] to [7] above, wherein the measured values of the converter obtained at the start of blowing and during blowing include the temperature of hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

[0034] [9]A blowing control system for a converter, comprising:

[0035] A sublance that measures a sublance measurement value including at least the temperature of the molten metal in the furnace during blowing in which an oxidizing gas is blown into the hot metal in the converter to carry out decarburization refining of the hot metal;

[0036] The first computer successively estimates the estimated value of the molten metal temperature at the time of blowing, i.e., the in-blowing temperature estimated value, and the estimated value of the carbon concentration in the molten metal, i.e., the in-blowing carbon concentration estimated value, based on the operating conditions and measured values of the converter obtained at the start and during blowing, and calculates the amount of oxygen to be supplied and whether to input a cooling material or a heating material and the input amount so that the temperature and component concentration of the molten steel at the end of blowing become target values based on the sublance measured values actually measured by the sublance;

[0037] The operation control computer controls the operating conditions in such a way that the temperature of the molten steel and the carbon concentration in the molten steel at the end of blowing become target values based on the amount of oxygen and the input amount of the cooling material or the heating material calculated by the first computer;

[0038] The second computer sets the target value of the molten metal temperature at the sublance input time, i.e., the midway temperature target value, and sets the confirmation timing for confirming the difference between the midway temperature target value and the predicted midway temperature value, i.e., the midway temperature difference, during blowing before the sublance input time, where the predicted midway temperature value is the predicted value of the molten metal temperature at the sublance input time,

[0039] Moreover, the second computer calculates the difference between the midway temperature target value and the predicted midway temperature value, i.e., the midway temperature difference, and determines whether to input a cooling material or a heating material into the converter during blowing after the confirmation timing and before the sublance input based on the absolute value of the calculated midway temperature difference; and

[0040] The third computer calculates the input amount of the cooling material or the input amount of the heating material when the cooling material or the heating material is input.

[0041]

[10] In the blowing control system of the converter according to [9] above, either or both of an exhaust gas flowmeter and an exhaust gas analyzer are provided in the exhaust gas treatment equipment of the converter, and either or both of the exhaust gas data measured by the exhaust gas flowmeter and the exhaust gas analyzer are sent from the exhaust gas flowmeter and the exhaust gas analyzer to the first computer, and the first computer is configured to use the sent exhaust gas data for the successive estimation of the in-blowing temperature estimated value and the in-blowing carbon concentration estimated value.

[0042]

[11] The blowing control system of the converter according to [9] or

[10] above includes: a spectroscopic camera disposed around the converter, which photographs the furnace mouth combustion flame from the gap between the converter and the movable hood; and an image analysis device which records the image data sent from the spectroscopic camera in a removable manner and calculates the emission intensity of the wavelength in the range of 580 - 620 nm of the emission spectrum of the image data,

[0043] The data of the luminous intensity is sent from the image analysis device to the first computer, and the first computer is configured to use the sent data of the luminous intensity for successive estimation of the temperature estimated value during blowing and the carbon concentration estimated value during blowing.

[0044]

[12] The blowing control system of the converter according to any one of the above [9] to

[11] includes a temperature measuring device that optically measures the temperature of hot metal during the period when the hot metal used as a raw material for converter blowing is charged into the converter as the temperature of the hot metal at the time of charging. The data of the temperature measurement value of the temperature measuring device is sent from the temperature measuring device to the first computer, and the first computer is configured to use the sent data of the temperature measurement value for successive estimation of the temperature estimated value during blowing and the carbon concentration estimated value during blowing.

[0045] Effects of the Invention

[0046] According to the present invention, in a converter operation method of controlling the molten steel temperature and the molten steel composition at the time of stopping blowing to a target value by using static control and dynamic control, by the correction under dynamic control, the temperature of the molten metal at the intermediate sublance insertion time is controlled within a range that can make the molten steel temperature and the molten steel composition at the time of stopping blowing reach the target value. Therefore, the molten steel temperature and the molten steel composition at the time of stopping blowing can reach the target value with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Figure 1 FIG. is an example of a flowchart showing a blowing control system that proceeds according to the oxygen blowing process in an embodiment of the present invention.

[0048] Figure 2 Figure 2 FIG. is a schematic diagram of a converter facility having a preferable blowing control system in implementing the present invention.

[0049] Figure 3 Figure 3 FIG. is a schematic diagram for measuring the temperature of hot metal flowing from the hot metal holding container into the converter.

[0050] Figure 4 Figure 4 FIG. is a graph showing the relationship between the temperature of the molten metal and the carbon concentration in the molten metal at the intermediate sublance insertion time in an example of the present invention and a comparative example.

[0051] Figure 5 Figure 5 FIG. is a graph showing the error between the target molten steel temperature at the time of stopping blowing and the actual molten steel temperature at the time of stopping blowing in an example of the present invention and a comparative example. DETAILED DESCRIPTION OF THE INVENTION ​​​​​​​​​​

[0052] Hereinafter, the operation method of the converter of the present invention and the blowing control system of the converter will be described.

[0053] In the converter operation for decarburizing and refining hot metal to produce molten steel by oxygen blowing from a top blowing lance, in order to control the molten steel temperature and molten steel component concentrations such as carbon concentration at the end of oxygen blowing (end) to target values, a blowing control combining static control and dynamic control is performed. In the operation method of the converter of the present invention, static control and dynamic control are also combined to control blowing.

[0054] In static control, using a mathematical model based on heat balance calculation and material balance calculation, the oxygen supply amount and the input amount of cooling material or heating material required to control the molten steel temperature and molten steel component concentrations to target values are determined before the start of blowing. Then, according to the determined oxygen supply amount and the input amount of cooling material or heating material, blowing is started and carried out. After blowing continuously for a certain time (for example, at the moment when 80 - 90% of the oxygen supply amount calculated by static control is blown in, etc.), a sublance is inserted into the furnace. Using this sublance, the temperature of the molten metal in the furnace, or both the temperature and carbon concentration of the molten metal in the furnace are measured. The sublance inserted into the converter during the middle of blowing is also called the "midway sublance".

[0055] In dynamic control, using the sublance measurement values measured by the sublance (molten metal temperature, or both molten metal temperature and carbon concentration in the molten metal), and a mathematical model based on heat balance, material balance, and reaction model, the oxygen supply amount, the input amount of cooling material or heating material determined by static control are corrected, and finally the oxygen supply amount and the input amount of cooling material or heating material until the end of blowing are determined.

[0056] Here, the so-called "molten metal" is hot metal or molten steel. In the oxygen blowing (decarburizing refining) in the converter for producing molten steel from hot metal, the hot metal charged into the furnace becomes molten steel through a decarburization reaction. It is difficult to distinguish between hot metal and molten steel during the middle of oxygen blowing. Therefore, in this specification, hot metal and molten steel are uniformly represented as molten metal. When the distinction between hot metal and molten steel is clear, it is represented as "hot metal" or "molten steel".

[0057] The calculation formula of the heat balance calculation in static control is composed of, for example, an input heat determination term, a heat dissipation determination term, a cooling term or a heating term, an error term, and a temperature correction term by the operator. In addition, the calculation formula of the oxygen supply amount (oxygen supply) is composed of, for example, hot metal components, auxiliary raw material input amount, target molten steel temperature and target molten steel components at the end of blowing.

[0058] However, since static control is ultimately calculated based on the information before the start of blowing, errors occur in static control when the secondary combustion rate and the yield rate of auxiliary raw materials change due to changes in the furnace condition, lance height, and oxygen supply volume. That is, the input timing of the sublance determined by static control may not be accurate. Therefore, in Patent Documents 2 and 3, based on the information of the converter exhaust gas (exhaust gas flow rate, exhaust gas composition) and the spectroscopic information at the furnace mouth, the carbon concentration of the molten metal during blowing is successively estimated, and the sublance is inserted midway when the decarburization oxygen efficiency starts to decrease. Here, the "decarburization oxygen efficiency" refers to the ratio of the oxygen supplied to the furnace that contributes to the decarburization reaction, and the "lance height" refers to the distance from the tip of the top-blown lance to the static bath surface of the hot metal in the converter. In addition, "secondary combustion" refers to the phenomenon in which the CO gas generated in the furnace by the decarburization reaction burns into CO2 gas by the oxygen supplied from the top-blown lance.

[0059] However, in order to control the molten steel temperature and the carbon concentration in the molten steel within the target range at the end of blowing, it is insufficient to perform only the control that estimates the change in the carbon concentration during blowing.

[0060] As a result of repeated intensive research by the inventors of the present application, it was found that the reason for the lack of improvement in the control accuracy of the molten steel temperature at the end of blowing is the deviation in the temperature of the molten metal at the time of inserting the sublance midway. In particular, it was found that when the deviation between the input timing of the sublance midway determined by the start of the decrease in the decarburization oxygen efficiency obtained by successive estimation of the carbon concentration in the molten metal and the input timing of the sublance midway determined by static control is large, the deviation in the temperature of the molten metal at the time of inserting the sublance midway becomes large.

[0061] It is considered that the reason for this deviation in the input timing of the sublance midway is that the oxygen blown in is not used for the reaction with the components or auxiliary raw materials in the molten metal estimated by static control. For example, the deviation in the proportion used for secondary combustion or the combustion of iron in the molten metal becomes the cause of the deviation. However, it is difficult to accurately reflect these deviations in static control.

[0062] Therefore, the inventors of the present application believe that it is possible to not only successively estimate the carbon concentration of the molten metal during blowing, but also successively estimate the temperature of the molten metal, and use the successive estimated value of the molten metal temperature to perform an action (operation) to adjust the temperature of the molten metal before inserting the sublance midway, so that the temperature of the molten metal at the time of inserting the sublance midway is within the range that can be corrected by dynamic control.

[0063] The successive estimation of the carbon concentration of the molten metal in the present invention can apply the methods described in Patent Document 2 and Patent Document 3. That is, based on the measurement results of the temperature and component concentration of the molten metal at least one of before the start of blowing and during blowing, the information on the flow rate and component concentration of the exhaust gas, the information related to the optical characteristics of the mouth part of the converter (mouth part spectroscopic actual situation, mouth part optical characteristic information), the information on the oxygen supply amount and oxygen supply speed, the information on the flow rate of the stirring gas, and the information on the input amount of raw materials (main raw materials, auxiliary raw materials), etc., the carbon concentration in the molten metal is estimated. Here, as the information related to the optical characteristics of the mouth part of the converter, for example, the emission spectrum of the mouth combustion flame ejected from the mouth of the converter or the emission spectrum of the tapping port combustion flame can be measured, and the information on the time change of the emission intensity of the wavelength in the range of 580 to 620 nm of the measured emission spectrum can be calculated.

[0064] The successive estimation of the molten metal temperature in the present invention is carried out as follows. First, based on the oxygen supply amount, the oxygen input amount such as the input iron oxide, and the oxygen output amount obtained from the exhaust gas flow rate and exhaust gas components (CO gas concentration, CO2 gas concentration, O2 gas concentration, etc.), the oxygen amount used for the combustion of carbon in the molten metal is obtained by performing correction calculations in such a way that the oxygen balance in the furnace becomes the minimum. Then, the carbon concentration in the molten metal is estimated from the carbon amount in the combusted molten metal. At this time, the molten metal temperature is estimated by converting the change in the calculated carbon concentration into reaction heat.

[0065] Furthermore, in the estimation calculation of the molten metal temperature, not only the carbon in the hot metal composition is taken as a calculation item, but also the reaction heat of silicon, manganese, phosphorus and iron in the hot metal composition with oxygen, as well as the heat absorption of iron scraps and auxiliary raw materials, the sensible heat of the gas corresponding to the exhaust gas flow rate, and the heat dissipation corresponding to the temperature of the converter scale are taken as calculation items. The above reaction heat is corrected by multiplying the coefficient determined by multiple regression based on past operation results to minimize the error between the measured value of the molten metal temperature by the intermediate sublance and the calculated molten metal temperature.

[0066] When the intermediate sublance is inserted at the timing when the decarburization oxygen efficiency starts to decrease, the error between the molten metal temperature and the estimated molten metal temperature at the insertion time of the intermediate sublance calculated by the previous static control is 19.6 °C in terms of the standard deviation 1σ. In contrast, when the intermediate sublance is inserted at the timing when the decarburization oxygen efficiency starts to decrease, the temperature error between the molten metal temperature and the estimated molten metal temperature at the insertion time of the intermediate sublance obtained by the successive calculation of the molten metal temperature is expressed as 14.4 °C in terms of the standard deviation 1σ. That is, by successively calculating the molten metal temperature to determine the insertion timing of the intermediate sublance, the temperature estimation accuracy at the insertion time of the intermediate sublance is improved.

[0067] For example, when the original unit of quicklime in the furnace is 5 - 15 kg / ton of hot metal, the target range for the molten steel temperature and the carbon concentration in the molten steel at the time of stopping blowing is set as the target molten steel temperature ±10°C and the target carbon concentration ±0.015 mass%. In this case, it was confirmed that if the carbon concentration in the molten metal at the time of the mid-way sublance insertion is 0.1 - 0.3 mass% and the temperature of the molten metal at the time of the mid-way sublance insertion is within the range from "the target temperature at the time of stopping blowing - 35°C" to "the target temperature at the time of stopping blowing - 65°C", the simultaneous compliance rate of the molten steel temperature and the carbon concentration in the molten steel at the time of stopping blowing is high (88%).

[0068] In the present invention, the carbon concentration in the molten metal at the time of the mid-way sublance insertion and the temperature of the molten metal at the time of the mid-way sublance insertion are set within the above ranges.

[0069] Next, an example of the embodiment of the present invention will be described according to the oxygen blowing process. Figure 1 FIG. shows an example of a flowchart of a blowing control system carried out according to the oxygen blowing process.

[0070] First, the hot metal conditions such as the temperature, the charged amount of hot metal, and the hot metal composition to be used or already used in this blowing are obtained (S - 1).

[0071] Next, in this blowing, the following two points are determined (S - 2). The determination time can be any time as long as it is before the confirmation timing in (2) below, but from the viewpoint of having sufficient time, it is preferably determined before about 1 / 2 of the predetermined blowing time, and more preferably determined before the start of blowing.

[0072] (1) Setting of the mid-way temperature target value

[0073] The "mid-way temperature target value" refers to the target value of the temperature of the molten metal at the time of the mid-way sublance insertion.

[0074] (2) Setting of the confirmation timing;

[0075] The "confirmation timing" refers to the timing (period or moment) for confirming the difference, i.e., the "mid-way temperature difference", between the target value of the temperature of the molten metal in the mid-way sublance insertion period, i.e., the "mid-way temperature target value", and the predicted value of the temperature of the molten metal in the sublance insertion period, i.e., the "mid-way temperature predicted value", during the period before the mid-way sublance insertion in the blowing.

[0076] The above-mentioned "midway temperature target value" is preferably determined in consideration of the target molten steel temperature at the end of blowing and the amount of slag in the furnace. For example, as shown in the following formula (1), it is preferably obtained by combining a linear equation of the target molten steel temperature at the end of blowing and a polynomial of the original unit of quicklime to be charged into the furnace during blowing. It should be noted that formula (1) is a combination with a polynomial of the original unit of quicklime to be charged, and the polynomial of the original unit of quicklime to be charged can be replaced with a polynomial of the predetermined amount of slag in the furnace based on the original unit of quicklime to be charged.

[0077] Midway temperature target value (°C) = Target molten steel temperature at the end of blowing (°C) - a×W - b×W 2 - c ··· (1)

[0078] Here, W is the original unit of quicklime during this blowing (kg / ton of hot metal), a (°C×ton of hot metal / kg), b (°C×(ton of hot metal) 2 / kg 2 )), and c (°C) is a coefficient. The coefficients a, b, and c are set using regression calculation based on past operation results to maximize the compliance rate at the end of blowing.

[0079] In addition, the confirmation timing is determined by the successive estimated value of the carbon concentration in the molten metal, for example, when the successive estimated value of the carbon concentration in the molten metal calculated successively during blowing reaches 1.0 mass%. It is particularly preferred to determine the confirmation timing when the successive estimated value of the carbon concentration in the molten metal is in the range of 0.6 to 1.4 mass%.

[0080] When the confirmation timing is determined as the timing when the successive estimated value of the carbon concentration in the molten metal exceeds 1.4 mass%, the confirmation timing is too early, and it may not be possible to cope with changes in the blowing conditions afterwards. On the other hand, when the confirmation timing is determined as the timing when the successive estimated value of the carbon concentration in the molten metal is less than 0.6 mass%, the confirmation timing is too late, and it may be possible to perform measurements using the midway sublance before all the auxiliary materials (cooling materials and heating materials) charged during the period from the confirmation timing to the midway insertion of the sublance react, resulting in a decrease in the accuracy of the subsequent dynamic control.

[0081] During the blowing after the start of blowing, exhaust information such as the flow rate and composition of the converter exhaust is successively obtained. At the same time, oxygen supply information (S - 3) including the oxygen supply amount and oxygen supply rate from the top - blowing lance is also successively obtained.

[0082] In addition, during the blowing process after the start of blowing, a mathematical model based on heat balance calculation and material balance calculation is used. Based on the operating conditions and measured values of the converter obtained at the start of blowing and during blowing in steps (S-1) and (S-3), the successive estimated values of the molten metal temperature at the time of blowing progress, namely the "temperature estimate during blowing", and the successive estimated values of the carbon concentration in the molten metal, namely the "carbon concentration estimate during blowing", are successively estimated (S-4).

[0083] As blowing progresses, the decarburization reaction also proceeds, reaching the "confirmation timing" where the successively calculated carbon concentration estimate during blowing falls within the range of 0.6 to 1.4 mass% (S-5). If blowing proceeds to the confirmation timing, the "midway temperature prediction value", which is the predicted value of the molten metal temperature as the time of sublance insertion, is calculated. The "midway temperature prediction value" determines the confirmation timing through the successive estimated value of the carbon concentration in the molten metal, and when the value of this carbon concentration, that is, the "carbon concentration estimate during blowing", is set as C x (mass%), it is estimated using the following formula (2).

[0084] Midway temperature prediction value (°C) = T(C x ) + d × (C x - C SL ) ··· (2)

[0085] Here, T(C x ) is the "temperature estimate during blowing" (°C) at the time when the "carbon concentration estimate during blowing" is C x (mass%), C x is the "carbon concentration estimate during blowing" (mass%) at the confirmation timing, and C SL is the carbon concentration (mass%) at the scheduled time of midway sublance insertion. d is the molten metal temperature rise rate (°C / mass%) when 1.0 mass% of carbon in the molten metal burns, and preferably the value obtained by multiple regression from the past actual performance of converter blowing is used.

[0086] That is to say, as shown in the above formula (2), the "midway temperature prediction value" is obtained through the "temperature estimate during blowing" and the "carbon concentration estimate during blowing".

[0087] Then, using the obtained "midway temperature target value" and the obtained "midway temperature prediction value", the above-mentioned "midway temperature difference" is calculated (S-6).

[0088] Since the "midway temperature target value" is represented by formula (1) and the "midway temperature prediction value" is represented by formula (2), according to formula (1) and formula (2), the difference between the "midway temperature prediction value" and the "midway temperature target value" at the time of midway sublance insertion, that is, the "midway temperature difference", is represented by the following formula (3).

[0089] Midway temperature difference (°C) = Predicted midway temperature (°C) - Target midway temperature (°C) = T(C x ) + d×(C x -C SL )-[Target tapping temperature of molten metal (°C) - a×W - b×W 2 -c]···(3)

[0090] When the "midway temperature difference" calculated by formula (3) exceeds 0 (zero), the "predicted midway temperature" is higher than the "target midway temperature". On the other hand, when the "midway temperature difference" is less than 0 (zero), it corresponds to the case where the "predicted midway temperature" is lower than the "target midway temperature".

[0091] Therefore, regardless of whether the "midway temperature difference" is positive or negative, when the absolute value of the "midway temperature difference" is large, an action (operation) to correct the molten metal temperature is required. That is, when the absolute value of the "midway temperature difference" is larger than a predetermined threshold, an action is required to make the "predicted midway temperature" after the action approach the "target midway temperature".

[0092] Therefore, it is determined whether the "midway temperature difference" is larger than a predetermined threshold (positive number) (S - 7). When the "midway temperature difference" is positive and exceeds the threshold (positive number), a cooling material is added to lower the molten metal temperature (S - 8).

[0093] When the "midway temperature difference" is less than or equal to the predetermined threshold (positive number), it is determined whether the "midway temperature difference" is smaller than the threshold (negative number) (S - 9). When the "midway temperature difference" is negative and smaller than the threshold (negative number), a heating material is added to increase the molten metal temperature (S - 10).

[0094] When the absolute value of the "midway temperature difference" is less than or equal to the predetermined threshold, no action is taken to adjust the molten metal temperature.

[0095] For example, if the predetermined threshold is set to 15 °C, when the "midway temperature difference" exceeds +15 °C, a cooling material such as scale and iron ore is added to the furnace to cool the molten metal in such a way that the "predicted midway temperature" after the action decreases and approaches the "target midway temperature". The input amount of the cooling material is determined by multiplying the "midway temperature difference" by the cooling coefficient. On the other hand, when the "midway temperature difference" is less than, for example, -15 °C, a heating material such as a carbon material (raising the temperature by the combustion of the contained carbon) and an Fe - Si alloy (raising the temperature by the combustion of the contained silicon (Si)) is added to the furnace to heat the molten metal. The input amount of the heating material is determined by multiplying the "midway temperature difference" by the heating coefficient.

[0096] The threshold value determined in advance as the absolute value of the "midway temperature difference" can be appropriately determined according to the situation of individual steelmaking plants, but is preferably a value selected from values of 10°C or more. For example, it is determined to be 15°C.

[0097] If the absolute value of the "midway temperature difference" is less than 10°C, then during the blowing after the confirmation timing and before the sublance is inserted, even if no cooling material or heating material is inserted into the converter, correction can be performed by dynamic control. Therefore, the predetermined threshold value only needs to be a value of 10°C or more. In addition, in the case where the absolute value of the "midway temperature difference" is larger, during the blowing after the confirmation timing and before the sublance is inserted, by increasing the input amount of the cooling material or heating material inserted into the converter, the amount of correction under dynamic control becomes smaller, and it is easy to make the molten steel temperature and molten steel composition at the end of blowing reach the target values. Therefore, it is not necessary to determine the upper limit of the absolute value.

[0098] Then, based on the "carbon concentration estimation value during blowing" which is the successive estimation value of the carbon concentration in the molten metal, the timing when the decarburization oxygen efficiency starts to decrease (as described later, the moment when the "carbon concentration estimation value during blowing" is about 0.45 mass%) is obtained, and the midway sublance is inserted at this timing.

[0099] After the midway sublance is inserted, according to the sublance measurement values measured by the midway sublance, dynamic control is implemented, and the operations indicated by the dynamic control are performed to end the oxygen blowing.

[0100] By performing the above operations, compared with the prior art, the temperature control of the molten metal at the midway sublance insertion moment becomes easier, and through the subsequent dynamic control, the molten metal temperature at the end of blowing can be controlled at the target value with high precision.

[0101] In the embodiment of the present invention, the key point for further reflecting the effect is to more accurately perform the successive estimation of the "temperature estimation value during blowing" and the "carbon concentration estimation value during blowing". Therefore, as the measurement values of the converter obtained at the start of blowing and during blowing, it is preferable to use either or both of the measurement value of the exhaust gas flow rate of the exhaust gas flowmeter provided in the flue of the exhaust gas treatment equipment of the converter and the measurement values of the exhaust gas components (CO gas concentration, CO2 gas concentration, O2 gas concentration, etc.) using the exhaust gas analyzer. Furthermore, it is preferable to use them in combination and adopt other measurement values useful for the successive estimation of the "temperature estimation value during blowing" and the "carbon concentration estimation value during blowing".

[0102] For example, as the measured value of the converter adopted, it is preferable to adopt the measured value of the optical characteristics of the converter mouth part during blowing, that is, the change rate of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag. By adopting this value, the successive estimation accuracy of the carbon concentration in the molten metal during blowing is improved. Specifically, as the optical characteristics of the converter mouth part, the maximum value of the luminous intensity in the wavelength band (spectrum) of light emitted along with the decarburization reaction, for example, in the wavelength band of 550 to 650 nm, is detected through the reduction reaction of iron oxide in the slag shown by the reaction formula of the following formula (4), and this measured value is used.

[0103] FeO +C→Fe+CO· · · (4)

[0104] When the carbon concentration in the molten metal reaches near the critical carbon concentration through oxygen supply decarburization, the efficiency (decarburization oxygen efficiency) of the decarburization reaction shown by the formula (4) decreases, and thus the luminous intensity in the wavelength range of 550 to 650 nm also decreases. Here, the so-called "critical carbon concentration" refers to the carbon concentration in the molten metal at the boundary where the decarburization reaction rate of oxygen supply decarburization changes from the state determined by the oxygen supply rate to the state determined by the movement (diffusion) of carbon in the molten metal. In other words, the "critical carbon concentration" is the carbon concentration in the molten metal at the moment when the decarburization oxygen efficiency begins to decrease. It should be noted that the critical carbon concentration varies depending on the stirring force of the top-blown gas and the bottom-blown gas on the molten metal and the flow rate of the oxidizing gas, and is approximately 0.45 mass%.

[0105] Therefore, in the embodiment of the present invention, it is preferable to calculate the change rate of the luminous intensity of the maximum value of the luminous intensity in the above-mentioned wavelength band and reflect it in the successive estimation of the carbon concentration in the molten metal during blowing. For example, the timing when the change rate of the luminous intensity changes from a positive value to a negative value can be detected as the timing when the carbon concentration in the molten metal reaches the critical carbon concentration.

[0106] In addition, for example, the measured value preferably adopted includes the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows into the converter from the hot metal holding container. By adopting this value, the successive estimation accuracy of the "temperature estimated value during blowing" is improved.

[0107] Specifically, as the initial value of the "estimated temperature during blowing", it is preferably a value determined based on the temperature of the hot metal measured when the hot metal flows from the hot metal holding vessel into the converter. Generally, as this initial value, the temperature measured by immersing a thermocouple in the hot metal filled in the hot metal holding vessel before charging it into the converter is used. However, after the temperature of the hot metal in the hot metal holding vessel is measured, during the period until it is charged into the converter, the temperature of the hot metal in the hot metal holding vessel drops, and the amount of the drop also varies depending on the charging, so the accurate hot metal temperature is not reflected as the initial value. Therefore, it is preferable to measure the temperature of the hot metal during the period when the hot metal is charged into the converter, and use the value determined based on this temperature as the initial value of the "estimated temperature during blowing". The initial value of the "estimated temperature during blowing" can directly use the temperature of the hot metal measured when the hot metal flows from the hot metal holding vessel into the converter, or can also use the value obtained by correcting the temperature of the hot metal measured when the hot metal flows from the hot metal holding vessel into the converter considering the time from tapping of the previous charge to the charging of the hot metal this time, that is, the empty furnace time, the amount of iron chips charged, etc.

[0108] The temperature of the hot metal when it flows from the hot metal holding vessel into the converter is measured using a non-contact optical method. Specifically, as this optical method, it is preferably to use a so-called two-color thermometer, which measures the emission spectrum radiated by the hot metal, and calculates the temperature of the hot metal from the ratio of the emission energies of two different wavelengths selected from the measured emission spectrum. This is because, by using a two-color thermometer as the temperature measuring device for optically measuring the temperature of the hot metal, even when the emissivity of the temperature measurement object changes, as long as the relationship between the two spectral emissivities with different wavelengths changes in a proportional relationship, the ratio of the two spectral emissivities depends only on the temperature and accurate temperature measurement can be performed without depending on the change in emissivity.

[0109] Here, when the two different wavelengths used in the two-color thermometer are set as λ1 and λ2 (λ2>λ1), it is preferable that both λ1 and λ2 are in the range of 400 nm to 1000 nm. When λ1 and λ2 are less than 400 nm, since the wavelength is short, it is difficult to detect the emission energy with a normal spectroscopic camera. On the other hand, when λ1 and λ2 exceed 1000 nm, since the wavelength is long, the influence of the change in the emissivity ratio becomes large. In addition, the absolute value of the difference between λ1 and λ2 is preferably 50 nm or more and 600 nm or less. When the absolute value of the difference between λ1 and λ2 is less than 50 nm, since the wavelengths of λ1 and λ2 are close, it is difficult to perform spectroscopy with a normal spectroscopic camera, so it is not preferable. On the other hand, when the absolute value of the difference between λ1 and λ2 exceeds 600 nm, one wavelength (λ2) must be selected from the long wavelength range. Since the wavelength is long, the influence of the change in the emissivity ratio becomes large, so it is not preferable.

[0110] When the temperature of hot metal measured by a non-contact optical method when the hot metal used as a raw material for blowing is poured from the hot metal holding vessel into the converter is used as the initial value of the "estimated temperature during blowing", the temperature error between the molten metal temperature when the intermediate lance is inserted at the timing when the decarburization oxygen efficiency starts to decrease and the "estimated temperature during blowing" at the time of inserting the intermediate lance obtained by successive calculation of the molten metal temperature is reduced to 12.9 °C in terms of the standard deviation 1σ. That is, by using the value determined based on the temperature of the hot metal measured by a non-contact optical method when flowing into the converter as the initial value of the "estimated temperature during blowing", the temperature estimation accuracy at the time of inserting the intermediate lance is further improved.

[0111] As the measured values of the converter adopted, in the case of including both the measured value of the optical characteristics of the converter mouth part during blowing (the change rate of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag) and the temperature of the hot metal measured when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter, either measurement can be handled by a spectroscopic camera. That is, both can be measured with one spectroscopic camera. Here, a spectroscopic camera generally refers to a general term for a camera that can capture spectroscopic data in addition to a planar image for measuring temperature such as a so-called thermal imager. It should be noted that spectroscopic data refers to data obtained by separately collecting multiple wavelengths included in the emitted light for each wavelength.

[0112] Hereinafter, with reference to the drawings, the structure of a converter apparatus having a preferred blowing control system in terms of the operation method of the converter for implementing the present invention will be described. Figure 2 A schematic diagram showing a converter apparatus preferred in terms of implementing the present invention.

[0113] A converter apparatus 1 preferred in terms of implementing the present invention includes a converter 2; a top blowing lance 3; a bottom blowing tuyere 4; an intermediate lance 5; a spectroscopic camera 7 disposed around the converter 2 and capable of photographing the furnace mouth combustion flame 18; an image analysis device 8 that records the photographed image taken by the spectroscopic camera 7 in a removable manner and analyzes the photographed image; a first computer 9 that inputs the data analyzed by the image analysis device 8; and an operation control computer 12 that inputs the data analyzed by the first computer 9.

[0114] In addition, there is a second computer 10 that inputs the data analyzed by the first computer 9, and a third computer 11 that inputs the data analyzed by the second computer 10. The data analyzed by the second computer 10 and the data analyzed by the third computer 11 are input to the operation control computer 12. The first computer 9, the second computer 10, and the third computer 11 may also be constituted by one computer. The operation control computer 12 sends a control signal based on the data input from the first computer 9 and the third computer 11.

[0115] Furthermore, there are provided a lance height control device 13, a sublance lifting control device 14, an oxidizing gas flow control device 15, a bottom-blow gas flow control device 16, and a submaterial input control device 17, which are configured to operate independently according to control signals sent from the operation control computer 12. The lance height control device 13 is a device for adjusting the lance height of the top-blow lance 3, and the sublance lifting control device 14 is a device for controlling the lowering and raising of the sublance 5. The oxidizing gas flow control device 15 is a device for adjusting and measuring the flow rate of the oxidizing gas ejected from the top-blow lance 3. The bottom-blow gas flow control device 16 is a device for adjusting the flow rate of the stirring gas blown in from the bottom-blow tuyere 4, and the submaterial input control device 17 is a device for controlling the type and input amount of the submaterials stored in the furnace charging hopper 24.

[0116] For feedback control, the actual values of these control devices are input to the operation control computer 12. Here, the submaterials refer to the general term of fluxing agents such as quicklime, cooling materials such as iron ore, and heating materials such as carbon materials. Relative to the submaterials, the main materials are hot metal and iron scraps.

[0117] In addition, an exhaust gas flowmeter 22 for measuring the flow rate of the exhaust gas discharged from the converter 2 and a gas analyzer 23 for analyzing the composition of the exhaust gas (CO gas, CO2 gas, O2 gas, etc.) are provided on the flue 29 for exhausting the exhaust gas, which is provided above the furnace mouth 20. The measured values of the exhaust gas flowmeter 22 and the gas analyzer 23 are input to the first computer 9.

[0118] The converter 2 used in the present invention is configured to be able to blow the stirring gas from the bottom-blow tuyere 4 at the bottom of the furnace while ejecting the oxidizing gas jet 19 from the top-blow lance 3 into the hot metal 6 in the furnace. As the oxidizing gas ejected from the top-blow lance 3, pure oxygen (industrial pure oxygen) or a mixed gas of oxygen and an inert gas is used. Usually, pure oxygen is used as the oxidizing gas.

[0119] Data such as the composition (C, Si, Mn, P, S, etc.), temperature, mass of the hot metal 6 used in the blowing (charging), and the mass (charged amount) of the iron scraps during the blowing are input from a converter process computer (not shown) to the first computer 9. In addition, the measured values of the sublance 5, that is, the measured value of the molten metal temperature or the measured values of both the molten metal temperature and the carbon concentration in the molten metal, are input to the first computer 9. Moreover, the target values of the molten steel temperature and the target values of the molten steel component concentrations such as the carbon concentration at the end of the oxygen blowing are input from the converter process computer to the first computer 9. It should be noted that the target values of the molten steel temperature and the target values of the molten steel component concentrations such as the carbon concentration at the end of the oxygen blowing can also be directly set in the first computer 9.

[0120] Before the start of the blowing process, the first computer 9 performs static control using a mathematical model based on heat balance calculation and material balance calculation, based on the target values of the molten steel temperature and the molten steel composition concentration at the end of the blowing process, which are input, and the composition, temperature, mass of the hot metal 6, and the mass of the iron filings, which are input. Further, the first computer 9 calculates the oxygen supply amount, the flux input amount, and the input amount of the cooling material or the heating material required to control the molten steel temperature and the molten steel composition concentration at the end of the blowing process to the target values, as the data for static control. That is, the first computer 9 performs static control before the start of the blowing process.

[0121] The data for static control performed by the first computer 9 is input to the operation control computer 12. Based on the data for static control input from the first computer 9, the operation control computer 12 sends control signals to the lance height control device 13, the oxidizing gas flow control device 15, the bottom blowing gas flow control device 16, and the auxiliary material input control device 17, respectively, so that the molten steel temperature and the molten steel composition concentration at the end of the blowing process become the target values. In this way, the blowing process based on static control is started.

[0122] During the blowing process after the start of the blowing process, the first computer 9 uses a mathematical model based on heat balance calculation and material balance calculation, and based on the operation conditions and measured values of the converter obtained at the start and during the blowing process, sequentially estimates the sequential estimated value of the molten metal temperature at each moment during the blowing process, i.e., the "in-blowing temperature estimated value", and the sequential estimated value of the carbon concentration in the molten metal, i.e., the "in-blowing carbon concentration estimated value".

[0123] As a method for sequentially estimating the "in-blowing carbon concentration estimated value", for example, the supply amount of the oxidizing gas input from the oxidizing gas flow control device 15, the carbon concentration of the hot metal 6 before oxygen blowing input from the converter process computer, the measured value of the exhaust gas flow input from the exhaust gas flowmeter 22, and the measured value of the exhaust gas composition input from the gas analyzer 23 are used to perform the material balance calculation of carbon and oxygen in the decarburization reaction, and the carbon concentration of the molten metal in the furnace is estimated.

[0124] The second computer 10 sets the aforementioned "midway temperature target value" and the "confirmation timing". The "midway temperature target value", which is the target value of the molten metal temperature at the midway sublance insertion time, is calculated using the above formula (1). The setting time can be any time as long as it is before the "confirmation timing", but it is preferably determined about 1 / 2 of the predetermined blowing time before, and more preferably determined before the start of the blowing process.

[0125] Here, as described above, the "confirmation timing" refers to the timing of confirming the "midway temperature difference", which is the difference between the above-mentioned "midway temperature target value" and the predicted value of the molten metal temperature during the period when the sublance is inserted midway during the blowing process, i.e., the "midway temperature predicted value". It should be noted that the confirmation timing is preferably determined as the timing when the "carbon concentration during blowing estimated value" of the successive estimated values calculated by the first computer 9 is within the range of 0.6 to 1.4 mass%.

[0126] After the blowing process proceeds and the "carbon concentration during blowing estimated value" successively calculated by the first computer 9 reaches the "confirmation timing", the first computer 9 inputs the signal of the "carbon concentration during blowing estimated value" to the second computer 10. If the "confirmation timing" is input from the first computer 9, the second computer 10 calculates the "midway temperature predicted value" using the aforementioned formula (2). Then, using the calculated "midway temperature predicted value" and the above-mentioned "midway temperature target value" that has already been calculated, the "midway temperature difference" is calculated through the above formula (3).

[0127] Based on the absolute value of the calculated "midway temperature difference", the second computer 10 determines whether to input cooling materials or heating materials into the converter during the blowing process before the sublance is inserted. Specifically, for example, the threshold value of the absolute value of the "midway temperature difference" is set to 15°C. When the "midway temperature difference" exceeds +15°C, it is determined that cooling materials such as scale and iron ore are input into the furnace. On the other hand, when the "midway temperature difference" is less than -15°C, it is determined that heating materials such as carbon materials and Fe-Si alloys are input into the furnace. In this case, if the absolute value of the "midway temperature difference" is 15°C or less, the input of cooling materials and heating materials is not implemented. When the "midway temperature difference" is a positive number exceeding +15°C, cooling materials are input. When the "midway temperature difference" is a negative number exceeding -15°C, heating materials are input. Therefore, the absolute value of the "midway temperature difference" at the time of the subsequent sublance insertion becomes smaller. That is, by inputting cooling materials or heating materials, the difference between the midway temperature target value and the midway temperature predicted value at the sublance insertion time becomes smaller. The second computer 10 sends the presence or absence of the input of cooling materials or heating materials to the third computer 11 and the operation control computer 12.

[0128] If the third computer 11 receives a signal indicating the input of a cooling material or a heating material from the second computer 10, it calculates the input amount of the cooling material or the heating material. The input amounts of the cooling material and the heating material are calculated based on the absolute value of the "intermediate temperature difference". For example, if the cooling material is iron ore, when the "intermediate temperature difference" exceeds +15°C and is +20°C or less, the cooling material is input at a rate of 2.7 kg / ton of hot metal. When the "intermediate temperature difference" exceeds +20°C and is +25°C or less, the cooling material is input at a rate of 3.6 kg / ton of hot metal, etc. When the "intermediate temperature difference" is positive, the larger the "intermediate temperature difference", the greater the input amount of the cooling material. On the other hand, when the "intermediate temperature difference" is negative, the larger the absolute value of the "intermediate temperature difference", the greater the input amount of the heating material.

[0129] The calculated input amounts of the cooling material and the heating material are sent from the third computer 11 to the operation control computer 12. The operation control computer 12, which has received the signals of the input amounts of the cooling material and the heating material from the third computer 11, sends a control signal to the auxiliary raw material input control device 17 to input a specified amount of the cooling material or the heating material into the furnace. The auxiliary raw material input control device 17, which has received this control signal, inputs a specified amount of the cooling material or the heating material into the furnace.

[0130] Then, if the "estimated carbon concentration during blowing" successively calculated by the first computer 9 reaches the carbon concentration (about 0.45 mass%) at which the decarburization oxygen efficiency starts to decrease, the first computer 9 sends this signal to the operation control computer 12. The operation control computer 12, which has received this signal, sends a control signal for inserting the sublance to the sublance lifting control device 14. The sublance lifting control device 14, which has received this control signal, inserts the sublance 5 into the furnace.

[0131] The sublance 5 measures the molten metal temperature, or measures both the molten metal temperature and the carbon concentration in the molten metal. Here, the molten metal temperature is measured by a thermocouple in the sublance probe provided at the tip of the sublance 5. In addition, the carbon concentration in the molten metal is obtained from the cooling curve when the molten metal collected by the molten metal sampler in the sublance solidifies in the molten metal sampler. The sublance measurement value of the sublance 5, that is, the measured value of the molten metal temperature, or the measured values of both the molten metal temperature and the carbon concentration in the molten metal are sent to the first computer 9.

[0132] Based on the sublance measurement value actually measured by the sublance 5, the first computer 9 calculates the amount of oxygen to be supplied in order to make the temperature and composition concentration of the molten steel reach the target value when blowing stops, and whether it is necessary to input a cooling material or a heating material and the input amount. That is, the first computer 9 performs dynamic control after the sublance is inserted.

[0133] The dynamically controlled signal of the first computer 9 is sent to the operation control computer 12. The operation control computer 12 that receives the dynamically controlled signal of the first computer 9 sends a control signal to the oxidizing gas flow control device 15 to supply a specified amount of oxidizing gas into the furnace. At the same time, a control signal is sent to the auxiliary raw material input control device 17 to input a specified amount of cooling material or heating material into the furnace. The oxidizing gas flow control device 15 that receives this control signal supplies a specified amount of oxygen into the furnace. In addition, the auxiliary raw material input control device 17 that receives the control signal from the operation control computer 12 inputs a specified amount of cooling material or heating material into the furnace.

[0134] If the supply of oxygen amount and the input of cooling material or heating material based on the dynamic control of the first computer 9 are completed, the oxygen blowing is terminated.

[0135] With the blowing control system configured as described above, compared with the prior art, the molten metal temperature control at the intermediate sublance insertion time becomes easier, and through subsequent dynamic control, the molten metal temperature at the end of blowing can be accurately controlled to the target value with high precision.

[0136] In the present invention, in order to more accurately perform successive estimation of the "temperature estimated value during blowing" and the "carbon concentration estimated value during blowing", as described above, as the measured values of the converter obtained at the start and during blowing, it is preferable to use the measured value of the optical characteristics of the converter furnace mouth part during blowing and / or the measured value of the molten iron temperature measured by a non-contact optical method when the molten iron flows from the molten iron holding container into the converter.

[0137] In the converter equipment 1 used in the present invention, in order to measure the measured value of the optical characteristics of the converter furnace mouth part and the measured value of the molten iron temperature measured by a non-contact optical method, as Figure 2 shown, a spectroscopic camera 7 is provided. Figure 2 In the figure, reference numeral 25 is the input chute for auxiliary raw materials, reference numeral 26 is the oxidizing gas supply pipe for the top-blown lance, reference numeral 27 is the cooling water supply pipe for the top-blown lance, and reference numeral 28 is the cooling water discharge pipe for the top-blown lance.

[0138] Around the converter 2, a spectroscopic camera 7 is installed at a position where the emission spectrum of the furnace mouth combustion flame 18 of the converter can be measured. Through the installed spectroscopic camera 7, the furnace mouth combustion flame 18 seen from the gap between the furnace mouth 20 of the converter and the movable hood 21 is photographed. The photographed image (image data) taken by the spectroscopic camera 7 is successively sent to the image analysis device 8. In the image analysis device 8, the sent photographed image (image data) is recorded, and line analysis is performed on an arbitrary scan line of the image data to analyze the emission wavelength and the emission intensity of each wavelength.

[0139] The image data of the combustion flame 18 at the furnace mouth after analysis is sent to the first computer 9 each time. When the first computer 9 successively estimates the "estimated value of the carbon concentration during blowing" through the material balance calculation of oxygen and carbon, it uses the analysis image data of the emission spectrum of the combustion flame 18 at the furnace mouth input from the image analysis device 8 to successively estimate the "estimated value of the carbon concentration during blowing". Thus, the estimation accuracy of the "estimated value of the carbon concentration during blowing" is improved.

[0140] Here, the so-called "combustion flame at the furnace mouth" refers to the flame in the furnace blown out from the furnace mouth 20 of the converter 2 upward into the flue 29. The emission spectrum of the combustion flame 18 at the furnace mouth contains information related to CO gas and CO2 gas generated by the decarburization reaction in the converter, and information related to FeO* (intermediate product) from iron atoms evaporated from the fire point in the furnace. The above CO2 gas is generated by the spontaneous combustion caused by the mixing of a part of the CO gas with the air attracted at the converter furnace mouth part.

[0141] The inventors of the present application confirmed that in this emission spectrum, for wavelengths in the range of 580 - 620 nm, by measuring the emission intensity of each wavelength in real time, the in-furnace condition of the converter can be easily estimated in real time. Furthermore, the inventors of the present application confirmed that when FeO* is generated, an absorption peak is confirmed in this wavelength region, and on the other hand, when FeO* disappears, an emission peak is confirmed in the same wavelength region, where the emission intensity is linked to the disappearance rate of FeO*.

[0142] What is monitored is the electromagnetic wave of a specific wavelength emitted or absorbed during the electronic state transition of FeO* mainly generated at the fire point of the molten iron bath in the melting furnace. Since FeO* merges with the flame rising from the furnace, for example, when the decarburization reaction is approaching the end, the generation amount and reaction amount of FeO* decrease. Therefore, if the emission spectrum of this flame is spectroscopically analyzed, the emission intensity of wavelengths in the range of 580 - 620 nm decreases. That is, if the decarburization reaction rate is limited by the mass transfer rate of carbon in the molten metal, the formation of FeO is dominant compared to the reduction of FeO, and the emission intensity of wavelengths in the range of 580 - 620 nm drops sharply.

[0143] Next, a method for measuring the temperature of the molten iron 6 when the molten iron 6 used in this blowing flows from the molten iron holding container 30 into the converter 2 using the spectroscopic camera 7 will be described.

[0144] Figure 3Schematic diagram showing the measurement of the temperature of hot metal flowing from the hot metal holding vessel into the converter. When hot metal 6 used as the raw material for this blowing process flows from the hot metal holding vessel 30 into the converter 2, in the case of measuring the temperature of the hot metal, the spectroscopic camera 7 is installed, for example, in front of the furnace on the charging side of the converter, and can observe the location of the injection flow when the hot metal 6 flows from the hot metal holding vessel 30 into the converter 2. It is preferable to set the spectroscopic camera 7 at an angle looking up at the injection flow, as it is not easily affected by the dust generated during the charging of the hot metal. In the spectroscopic camera 7, during the period from the start to the end of the hot metal charging, two-color temperature information is collected at a preset sampling rate (for example, every 1 second).

[0145] The two-color temperature information collected by the spectroscopic camera 7 is sent to the image analysis device 8, and the hot metal temperature is calculated by the image analysis device 8. The calculated hot metal temperature is input to the first computer 9, and the first computer 9 uses the value determined based on the input hot metal temperature as the initial value of the "temperature estimation value during blowing" and performs successive calculations of the "temperature estimation value during blowing".

[0146] By using the value determined based on the hot metal temperature measured by the spectroscopic camera 7 as the initial value of the "temperature estimation value during blowing", the temperature estimation accuracy at the intermediate sublance insertion time is further improved.

[0147] As a method for measuring two-color temperature information using the spectroscopic camera 7, the spectroscopic camera 7 can collect multiple wavelength data, and the image analysis device 8 etc. can extract any two wavelength data from the obtained data. If the camera has a band-pass filter inside the spectroscopic camera, any two wavelengths can be extracted using this band-pass filter. In addition, most of the shooting of the spectroscopic camera 7 is carried out by a CCD element, but multiple CCD elements can also be installed, and each CCD element measures a different wavelength range.

[0148] The spectroscopic camera 7 can be set separately to measure the optical characteristics of the converter mouth during blowing (the rate of change of the spectral emission intensity caused by the reduction reaction of iron oxide in the slag) and to measure the temperature of the hot metal charged into the converter, or it can be shared. In the case of sharing, it is set at a location where both the furnace mouth combustion flame 18 visible through the gap between the furnace mouth 20 of the converter 2 and the movable hood 21 and the injection flow when the hot metal 6 flows from the hot metal holding vessel 30 into the converter 2 can be observed. Alternatively, a moving mechanism can be set so that it is set at a location where the injection flow when the hot metal 6 flows from the hot metal holding vessel 30 into the converter 2 can be observed during the hot metal charging, and can move to a location where the furnace mouth combustion flame 18 visible through the gap between the furnace mouth 20 of the converter 2 and the movable hood 21 can be observed after the hot metal charging and before the start of blowing.

[0149] As described above, according to the present invention, in a converter operation method for controlling the molten steel temperature and molten steel composition at the time of stopping blowing to a target value using static control and dynamic control, by correction under dynamic control, the molten metal temperature at the time of inserting the sublance midway is controlled within a range that enables the molten steel temperature and molten steel composition at the time of stopping blowing to reach the target value. Therefore, the molten steel temperature and molten steel composition at the time of stopping blowing can reach the target value with high precision.

[0150] Example

[0151] After subjecting hot metal to desulfurization treatment and dephosphorization treatment in advance, a top-bottom blown converter (top blown oxygen, bottom blown argon) with a capacity of 350 tons as shown in Figure 2 is used to perform oxygen blowing on 300 - 350 tons of hot metal through static control, midway sublance insertion, and dynamic control, and decarburization refining of the hot metal is carried out to produce molten steel. The target molten steel temperature at the time of stopping blowing varies depending on each blowing and is in the range of 1660 - 1700 °C. The range for reaching the target molten steel temperature at the time of stopping blowing in each blowing is the target molten steel temperature ±10 °C. The chemical composition and hot metal temperature of the hot metal used during blowing are shown in Table 1.

[0152] [Table 1]

[0153]

[0154] Based on the exhaust gas flowmeter and exhaust gas analyzer installed in the flue of the exhaust gas treatment equipment of the converter, and the relationship between the amount of oxygen supplied by the top blown lance and the amount of solid oxygen (such as iron ore) input, the combustion amount of the furnace interior components is determined in such a way that the oxygen balance error in the furnace becomes the minimum. The obtained reaction amount of the furnace interior components is converted into reaction heat, and the "temperature estimation value during blowing" is calculated successively. In addition, through the material balance calculation of oxygen and carbon, the "carbon concentration estimation value during blowing" is successively estimated.

[0155] At the time of charging hot metal into the converter, the hot metal seen between the converter furnace mouth and the hot metal holding container is photographed with a spectroscopic camera. In the obtained emission spectrum of the hot metal, the hot metal temperature at the time of charging into the converter is calculated from the emission intensities at wavelengths of 550 nm and 850 nm. In addition, during blowing, the emission spectrum of the furnace mouth combustion flame is photographed with a spectroscopic camera, and for wavelengths in the range of 580 - 620 nm in the emission spectrum, the emission intensity at each wavelength is measured in real time. The wavelength used is 610 nm. One spectroscopic camera is used, and it is installed at a location where it can observe the furnace mouth combustion flame and the injection flow of the hot metal flowing from the hot metal holding container into the converter using a moving mechanism.

[0156] In the example of the present invention, the molten iron temperature measured at the time of charging molten iron into the converter is used as the initial value of the "in-blowing temperature estimated value", and the successive calculation of the "in-blowing temperature estimated value" is carried out. In addition, when the "in-blowing carbon concentration estimated value" is estimated by using the material balance calculation of oxygen and carbon, the analysis image data of the luminous spectrum of the furnace mouth combustion flame is used together to carry out the successive estimation of the "in-blowing carbon concentration estimated value".

[0157] In addition, in the example of the present invention, the moment when the "in-blowing carbon concentration estimated value" reaches 1.2 mass% is determined as the "confirmation timing", and the "midway temperature target value" is obtained by the above formula (1) according to the target molten steel temperature at the end of each blowing. The "midway temperature target value" is within the range from "the target molten steel temperature at the end of blowing - 35°C" to "the target molten steel temperature at the end of blowing - 65°C".

[0158] Moreover, in the example of the present invention, at the moment when the "in-blowing carbon concentration estimated value" reaches 1.2 mass%, the "midway temperature difference" is obtained by using formula (3). When the obtained "midway temperature difference" exceeds +15°C, before the midway sublance is inserted, iron ore as a cooling material is charged into the furnace. On the other hand, when the "midway temperature difference" is lower than -15°C, before the midway sublance is inserted, a carbon material (carbon content 75 mass% or more) as a heating material is charged into the furnace.

[0159] The charging amounts of the iron ore as the cooling material and the carbon material as the heating material are the values obtained by multiplying the "midway temperature difference" by the cooling coefficient and the heating coefficient respectively. The cooling coefficient and the heating coefficient are obtained by multiple regression respectively from the past blowing calculation results. The cooling coefficient uses -0.18 [(iron ore·kg) / (molten iron·ton×°C)], and the heating coefficient uses +0.25 [(carbon material·kg) / (molten iron·ton×°C)].

[0160] Then, based on the "in-blowing carbon concentration estimated value" which is the successive estimated value of the carbon concentration in the molten metal, the timing when the decarburization oxygen efficiency starts to decrease (molten metal carbon concentration ≈ 0.45 mass%) is obtained, and the midway sublance is inserted at this timing.

[0161] After the midway sublance is inserted, according to the measured values of the molten metal temperature and the molten metal carbon concentration of the midway sublance, dynamic control is implemented, and the operations shown by the dynamic control are carried out to end the oxygen blowing.

[0162] On the other hand, in the comparative example, the molten iron temperature measured at the time of charging the molten iron into the converter is not used as the initial value of the "temperature estimation value during blowing", but the molten iron temperature measured by immersing a thermocouple in the molten iron filled in the molten iron holding vessel before charging into the converter is used as the initial value of the "temperature estimation value during blowing", and the successive calculation of the "temperature estimation value during blowing" is performed. In addition, the analysis image data of the luminous spectrum of the furnace mouth combustion flame is not used in combination, and the "carbon concentration estimation value during blowing" is estimated using the material balance calculation of oxygen and carbon.

[0163] Then, at the moment when the "carbon concentration estimation value during blowing" reaches 0.45% by mass, the sublance is inserted. Based on the measured values of the molten metal temperature and the carbon concentration in the molten metal measured by the sublance in the middle, dynamic control is implemented, and the operations shown by the dynamic control are performed to end the oxygen blowing.

[0164] Table 2 shows the test conditions and test results of the example of the present invention and the comparative example.

[0165] [Table 2]

[0166]

[0167] *1: The ratio of the measured value of the molten metal temperature using the sublance in the middle to satisfy the "midway temperature target value" of the sublance insertion period ±15°C and the measured value of the carbon concentration is 0.1 - 0.3% by mass

[0168] *2: The ratio of the molten steel temperature at the end of blowing to satisfy the target temperature ±10°C and the carbon concentration in the molten steel at the end of blowing is ±0.015% by mass

[0169] It can be confirmed that the passing rate of the example of the present invention at the end of blowing is as high as 87%, and compared with the comparative example, the passing rate at the end of blowing is greatly improved.

[0170] Figure 4 It is a graph showing the relationship between the molten metal temperature and the carbon concentration in the molten metal at the moment of inserting the sublance in the example of the present invention and the comparative example. From Figure 4 It can be seen that in the example of the present invention, it can be confirmed that the deviation of the molten metal temperature at the moment of inserting the sublance from the target molten steel temperature at the end of blowing becomes smaller, and the molten metal temperature at the moment of inserting the sublance is controlled.

[0171] Figure 5 It is a graph showing the error between the target molten steel temperature at the end of blowing and the actual molten steel temperature at the end of blowing in the example of the present invention and the comparative example. As Figure 5 shown, it can be confirmed that according to the present invention, the molten steel temperature at the end of blowing can be accurately controlled within the target molten steel temperature.

[0172] Explanation of reference numerals

[0173] 1 Converter equipment

[0174] 2 Converter

[0175] 3 Top-blowing lance

[0176] 4 Bottom-blowing tuyere

[0177] 5 Sub-lance

[0178] 6 Hot metal

[0179] 7 Spectrographic camera

[0180] 8 Image analysis device

[0181] 9 First computer

[0182] 10 Second computer

[0183] 11 Third computer

[0184] 12 Computer for operation control

[0185] 13 Lance height control device

[0186] 14 Sub-lance lifting control device

[0187] 15 Oxidizing gas flow control device

[0188] 16 Bottom-blowing gas flow control device

[0189] 17 Auxiliary material input control device

[0190] 18 Furnace mouth combustion flame

[0191] 19 Oxidizing gas jet

[0192] 20 Furnace mouth

[0193] 21 Movable hood

[0194] 22 Exhaust gas flowmeter

[0195] 23 Gas analyzer

[0196] 24 Furnace charging hopper

[0197] 25 Auxiliary material input chute

[0198] 26 Oxidizing gas supply pipe for top-blowing lance

[0199] 27 Cooling water supply pipe for top-blowing lance

[0200] 28 Cooling water discharge pipe for top-blowing lance

[0201] 29 Flue

[0202] 30 Hot metal holding vessel

Claims

1. A method for operating a converter, in which, during the blowing for decarburizing refining of hot metal by blowing an oxidizing gas into the hot metal in the converter, a sublance is inserted into the furnace and sublance measurement values including at least the temperature of the molten metal in the furnace are actually measured, and based on the actually measured sublance measurement values, the amount of oxygen to be supplied until the blowing is stopped and whether to insert a cooling material or a heating material and the insertion amount are determined, whereby the temperature and composition concentration of the molten steel at the end of blowing are controlled to target values, wherein, a target value of the molten metal temperature at the sublance insertion time, i.e., the intermediate temperature target value, is determined, and a confirmation timing for confirming the difference between the intermediate temperature target value and the predicted intermediate temperature value, i.e., the intermediate temperature difference, during the blowing before the sublance insertion time is determined, and the predicted intermediate temperature value is a predicted value of the molten metal temperature at the sublance insertion time. Based on the operating conditions and measurement values of the converter obtained at the start and during the blowing, the estimated value of the molten metal temperature at the blowing progress time, i.e., the in-blowing temperature estimated value, and the estimated value of the carbon concentration in the molten metal at the blowing progress time, i.e., the in-blowing carbon concentration estimated value, are successively estimated. And when the blowing progresses to the confirmation timing, the intermediate temperature difference is calculated based on the predicted intermediate temperature value obtained from the in-blowing temperature estimated value and the in-blowing carbon concentration estimated value and the determined intermediate temperature target value. When the absolute value of the calculated intermediate temperature difference is greater than a preset threshold value, during the blowing after the confirmation timing and before inserting the sublance, a cooling material or a heating material is inserted into the converter.

2. The operating method of the converter according to claim 1, wherein, The confirmation timing is determined based on the in-blowing carbon concentration estimated value.

3. The operation method of the converter according to claim 2, wherein, The confirmation timing is determined within the range where the in-blowing carbon concentration estimated value is 0.6 to 1.4 mass%.

4. The operating method of the converter according to any one of claims 1 to 3, wherein, The preset threshold value is a value selected from values of 10°C or more.

5. The operating method of the converter according to any one of claims 1 to 3, wherein, When the absolute value of the intermediate temperature difference is greater than the preset threshold value, the amount of the cooling material or the heating material inserted during the blowing after the confirmation timing and before inserting the sublance is determined based on one or more of the in-blowing temperature estimated value, the target value of the molten steel temperature at the end of blowing, and the amount of quicklime inserted into the converter during this blowing.

6. The operating method of the converter according to claim 4, wherein, When the absolute value of the intermediate temperature difference is greater than the preset threshold value, the amount of the cooling material or the heating material inserted during the blowing after the confirmation timing and before inserting the sublance is determined based on one or more of the in-blowing temperature estimated value, the target value of the molten steel temperature at the end of blowing, and the amount of quicklime inserted into the converter during this blowing.

7. The operating method of the converter according to any one of claims 1 to 3, wherein, The measurement values of the converter obtained at the start and during the blowing include either or both of the measurement values obtained by an exhaust gas flowmeter and an exhaust gas analyzer.

8. The operation method of the converter according to claim 4, wherein, The measurement values of the converter obtained at the start and during the blowing include either or both of the measurement values obtained by an exhaust gas flowmeter and an exhaust gas analyzer.

9. The operating method of the converter according to claim 5, wherein, The measurement values of the converter obtained at the start and during the blowing include either or both of the measurement values obtained by an exhaust gas flowmeter and an exhaust gas analyzer.

10. The operating method of the converter according to claim 6, wherein, The measured values of the converter obtained at the start and during the blowing include either or both of the measured values obtained by an exhaust gas flowmeter and an exhaust gas analyzer.

11. The operation method of the converter according to any one of claims 1 to 3, wherein, The measured values of the converter obtained at the start and during the blowing are measured values related to the optical characteristics of the mouth part of the converter during blowing, and include the rate of change of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.

12. The operating method of the converter according to claim 4, wherein, The measured values of the converter obtained at the start and during the blowing are measured values related to the optical characteristics of the mouth part of the converter during blowing, and include the rate of change of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.

13. The operating method of the converter according to claim 5, wherein, The measured values of the converter obtained at the start and during the blowing are measured values related to the optical characteristics of the mouth part of the converter during blowing, and include the rate of change of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.

14. The operating method of the converter according to claim 7, wherein, The measured values of the converter obtained at the start and during the blowing are measured values related to the optical characteristics of the mouth part of the converter during blowing, and include the rate of change of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.

15. The operation method of the converter according to any one of claims 1 to 3, wherein, The measured values of the converter obtained at the start and during the blowing include the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

16. The operating method of the converter according to claim 4, wherein, The measured values of the converter obtained at the start and during the blowing include the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

17. The operating method of the converter according to claim 5, wherein, The measured values of the converter obtained at the start and during the blowing include the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

18. The operating method of the converter according to claim 7, wherein, The measured values of the converter obtained at the start and during the blowing include the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

19. The method for operating a converter according to claim 11, wherein, The measured values of the converter obtained at the start and during the blowing include the temperature of the hot metal measured by a non-contact optical method when the hot metal used as the raw material for this blowing flows from the hot metal holding vessel into the converter.

20. Blowing control system for a converter, having: A sublance that, during blowing for decarburizing and refining hot metal by blowing an oxidizing gas into the hot metal in the converter, actually measures sublance measurement values including the temperature of the molten metal in the furnace; A first computer that, based on the operating conditions and measured values of the converter obtained at the start and during the blowing, sequentially estimates the estimated value of the molten metal temperature at the time of blowing progress, i.e., the estimated temperature during blowing, and the estimated value of the carbon concentration in the molten metal, i.e., the estimated carbon concentration during blowing, and calculates, based on the sublance measurement values actually measured by the sublance, the amount of oxygen to be supplied and whether to input a cooling material or a heating material and the input amount so that the temperature and composition concentration of the molten steel at the end of blowing become target values; An operation control computer that controls the operating conditions in such a way that the temperature of the molten steel and the carbon concentration in the molten steel at the end of blowing become target values, based on the amount of oxygen and the input amount of the cooling material or the heating material calculated by the first computer; A second computer that sets a target value of the molten metal temperature at the time of sublance insertion, i.e., the intermediate temperature target value, and sets a confirmation timing for confirming the difference between the intermediate temperature target value and the predicted intermediate temperature, i.e., the intermediate temperature difference, during the blowing before the sublance insertion time. The predicted intermediate temperature is the predicted value of the molten metal temperature at the time of sublance insertion. Furthermore, the second computer calculates the difference between the set intermediate temperature target value and the predicted intermediate temperature obtained from the temperature estimated value during blowing and the carbon concentration estimated value during blowing, i.e., the intermediate temperature difference, and determines whether to input a cooling material or a heating material into the converter during the blowing after the confirmation timing and before the sublance insertion, based on the absolute value of the calculated intermediate temperature difference; and A third computer that calculates the input amount of the cooling material or the heating material when the cooling material or the heating material is input.

21. The blowing control system of the converter according to claim 20, wherein, In the exhaust gas treatment equipment of the converter, there is either one or both of an exhaust gas flow meter and an exhaust gas analyzer. Data of the exhaust gas measured by either one or both of the exhaust gas flow meter and the exhaust gas analyzer are sent from the exhaust gas flow meter and the exhaust gas analyzer to the first computer, and the first computer is configured to use the sent exhaust gas data for the sequential estimation of the temperature estimated value during blowing and the carbon concentration estimated value during blowing.

22. The blowing control system for a converter according to claim 20 or 21, comprising: a spectroscopic camera that is arranged around the converter and captures the furnace mouth combustion flame from the gap between the converter and the movable hood; an image analysis device that records the image data sent from the spectroscopic camera in a removable manner and calculates the emission intensity of wavelengths in the range of 580 - 620 nm of the emission spectrum of the image data. Data of the emission intensity are sent from the image analysis device to the first computer, and the first computer is configured to use the sent data of the emission intensity for the sequential estimation of the temperature estimated value during blowing and the carbon concentration estimated value during blowing.

23. The blowing control system for a converter according to claim 20 or 21, comprising a temperature measuring device that optically measures the temperature of the hot metal as the temperature of the hot metal at the time of charging during the period when the hot metal used as the raw material for converter blowing is charged into the converter. Data of the temperature measurement value of the temperature measuring device are sent from the temperature measuring device to the first computer, and the first computer is configured to use the sent data of the temperature measurement value for the sequential estimation of the temperature estimated value during blowing and the carbon concentration estimated value during blowing.

24. The blowing control system of a converter according to claim 22, which includes a temperature measuring device that optically measures the temperature of hot metal as the temperature of the hot metal at the time of charging during the period when the hot metal used as a raw material for blowing in the converter is charged into the converter. The data of the temperature measurement value of the temperature measuring device is sent from the temperature measuring device to the first computer, and the first computer is configured to use the sent data of the temperature measurement value in the successive estimation of the temperature estimation value and the carbon concentration estimation value during blowing.

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