CN116547392A - Converter operation method and converter converting control system - Google Patents
Converter operation method and converter converting control system Download PDFInfo
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- CN116547392A CN116547392A CN202180081579.7A CN202180081579A CN116547392A CN 116547392 A CN116547392 A CN 116547392A CN 202180081579 A CN202180081579 A CN 202180081579A CN 116547392 A CN116547392 A CN 116547392A
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- 238000000034 method Methods 0.000 title claims abstract description 54
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 307
- 238000007664 blowing Methods 0.000 claims abstract description 304
- 229910052742 iron Inorganic materials 0.000 claims abstract description 152
- 229910052751 metal Inorganic materials 0.000 claims abstract description 149
- 239000002184 metal Substances 0.000 claims abstract description 149
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 131
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 130
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 109
- 239000010959 steel Substances 0.000 claims abstract description 109
- 239000000463 material Substances 0.000 claims abstract description 102
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 86
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 86
- 239000001301 oxygen Substances 0.000 claims abstract description 86
- 238000001816 cooling Methods 0.000 claims abstract description 58
- 238000010438 heat treatment Methods 0.000 claims abstract description 49
- 239000007789 gas Substances 0.000 claims description 98
- 238000005259 measurement Methods 0.000 claims description 37
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 34
- 238000012790 confirmation Methods 0.000 claims description 33
- 239000002994 raw material Substances 0.000 claims description 30
- 230000001590 oxidative effect Effects 0.000 claims description 22
- 230000003287 optical effect Effects 0.000 claims description 20
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 15
- 230000008859 change Effects 0.000 claims description 15
- 238000010191 image analysis Methods 0.000 claims description 12
- 239000002893 slag Substances 0.000 claims description 8
- 235000012255 calcium oxide Nutrition 0.000 claims description 7
- 239000000292 calcium oxide Substances 0.000 claims description 7
- 238000006722 reduction reaction Methods 0.000 claims description 7
- 238000001228 spectrum Methods 0.000 claims description 7
- 238000009529 body temperature measurement Methods 0.000 claims description 4
- 238000011017 operating method Methods 0.000 claims description 3
- 230000003068 static effect Effects 0.000 abstract description 32
- 239000000203 mixture Substances 0.000 abstract description 22
- 238000012937 correction Methods 0.000 abstract description 11
- 238000005261 decarburization Methods 0.000 description 29
- 238000004364 calculation method Methods 0.000 description 22
- 238000002485 combustion reaction Methods 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 18
- 238000000295 emission spectrum Methods 0.000 description 15
- 230000007423 decrease Effects 0.000 description 13
- 230000008569 process Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000003575 carbonaceous material Substances 0.000 description 6
- 238000005266 casting Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 239000000498 cooling water Substances 0.000 description 4
- 238000007670 refining Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000013178 mathematical model Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910000676 Si alloy Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
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- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 230000001373 regressive effect Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000001748 luminescence spectrum Methods 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
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- 239000002904 solvent Substances 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/527—Charging of the electric furnace
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C2005/5288—Measuring or sampling devices
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Analogue/Digital Conversion (AREA)
Abstract
A converter operation method for controlling the temperature of molten metal at the time of feeding a sublance in the middle to a range in which the temperature and composition of molten metal at the time of stopping blowing can be brought to target values by correction under dynamic control is provided. In a converter operation method for controlling the temperature and composition of molten steel at the time of stopping blowing to target values by using static control and dynamic control, in oxygen blowing of molten iron, a temperature estimate value in blowing, which is an estimate value of a molten metal temperature, and a carbon concentration estimate value in blowing, which is an estimate value of a carbon concentration in molten metal, are successively estimated (S-4), a difference (intermediate temperature difference) between a preset intermediate temperature target value and an intermediate temperature estimate value, which is an estimate value of a molten metal temperature at the time of sub-gun introduction, is obtained (S-6), and when the absolute value of the obtained intermediate temperature difference is greater than a preset threshold value, a cooling material or a heating material is introduced into a converter before sub-gun introduction (S-8, S-10), and the molten metal temperature at the time of sub-gun introduction is controlled.
Description
Technical Field
The present invention relates to a method of operating a converter for producing molten steel from molten iron by blowing oxidizing gas into molten iron in the converter from a top-blowing lance and oxygen blowing, and a blowing control system for the converter.
Background
In a converter for producing molten steel from molten iron, molten steel is produced by decarburization refining of molten iron by oxygen blowing (hereinafter also simply referred to as "blowing") from a top-blowing lance. In this converter operation, static control and dynamic control are performed as a blowing control method for making the molten steel temperature and the molten steel component concentration at the time of stopping the oxygen blowing (at the time of ending) reach target values. Wherein, the static control is as follows: before the start of the blowing, the amount of oxygen to be supplied to the molten steel and the molten steel components at the time of stopping the blowing are calculated based on the information of the molten iron and the scrap iron used for the blowing, and the amount of auxiliary raw material to be charged to the molten steel and the molten steel components at the time of stopping the blowing are calculated to be target values.
The dynamic control is as follows: based on information obtained from a sublance placed in a converter during blowing (hereinafter also referred to as "intermediate sublance"), that is, a sublance measurement value (molten metal temperature, or both of the molten metal temperature and the carbon concentration in the molten metal), the amount of oxygen to be supplied and the amount of the placed auxiliary raw material are optimized, and the molten steel temperature and the molten steel composition at the time of stopping blowing are adjusted to target values. Conventionally, a sublance measurement value is obtained by charging a sublance at a timing when an oxygen amount obtained by subtracting a predetermined amount of oxygen amount from a supplied oxygen amount obtained by static control is supplied.
By the static control, when the deviation between the sub-gun measurement value of the sub-gun and the target molten steel temperature and the target carbon concentration at the time of stopping blowing becomes large, it is difficult to perform correction under the dynamic control. As a result, the molten steel temperature, the carbon concentration in the molten steel, and/or the oxygen concentration at the time of stopping blowing greatly deviate from the target values.
When the molten steel temperature at the time of stopping blowing is higher than the target temperature, the blowing time becomes longer and productivity becomes worse, and the melting loss of the lining refractory of the converter becomes larger, and the repair cost of the lining refractory increases, due to the addition of the cooling material into the furnace. On the other hand, when the molten steel temperature at the time of stopping the blowing is lower than the target temperature, the blowing is restarted, and the temperature is raised by the combustion of iron (Fe) in the molten steel. Since the blowing is restarted, the oxygen content in the molten steel at the time of stopping the blowing is higher than the target value, the amount of aluminum (Al) metal for deoxidizing the molten steel is increased, and the manufacturing cost is increased. In this case, by restarting the blowing, the carbon content in the molten steel at the time of stopping the blowing generally becomes lower than the target value.
Therefore, a technique for achieving target values of the molten steel temperature and the molten steel components (carbon concentration and oxygen concentration) at the time of stopping the oxygen blowing is demanded.
In order to achieve the target values of the molten steel temperature and the molten steel composition at the time of stopping the blowing by using the static control and the dynamic control, it is necessary to control the molten metal temperature at the time of charging the sub-lance in the middle and the sub-lance measurement value of the carbon concentration in the molten metal to be within a range that can easily achieve the target values of the molten steel temperature and the molten steel composition at the time of stopping the blowing by the correction under the dynamic control.
Conventionally, as a method for determining the time to throw in a sub-gun in the middle, for example, in patent document 1, a time required for dynamic control is determined based on blowing conditions, an amount of oxygen to be blown in during the determined dynamic control time is calculated, and a time to blow in an amount of oxygen obtained by subtracting the calculated amount of oxygen from an amount of oxygen (a predetermined supply amount) obtained by static control is determined as the time to throw in a sub-gun in the middle.
In patent documents 2 and 3, the emission spectrum, the exhaust gas flow rate, and the exhaust gas component concentration observed from the mouth of the converter are measured, and the carbon concentration in the converter is successively estimated, whereby the timing at which the decarburization oxygen efficiency is reduced is determined as the switching timing between the static control and the dynamic control, that is, the timing at which the sublayers are put in the middle.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2007-327113
Patent document 2: japanese patent laid-open No. 2020-105611
Patent document 3: international publication No. 2019/220800
Disclosure of Invention
Problems to be solved by the invention
However, in the method disclosed in patent document 1, the measurement timing of the intermediate sub-gun is determined using static control, and when the blowing condition changes due to external disturbance, the measurement timing of the intermediate sub-gun becomes inappropriate. As a result, there is a possibility that a time for which dynamic control is not ensured or a time required from the time of putting the sublance in the middle to the time of stopping the blowing may be required, and the accuracy of dynamic control may be lowered.
In patent documents 2 and 3, the timing of putting in the sub-gun in the middle is determined based on a calculated value calculated successively from measured values, regardless of a change in the blowing condition. However, even when the sublance is in the middle of the feeding at the determined timing, the measured molten metal temperature and the measured carbon concentration in the molten metal do not necessarily reach the ranges that can be corrected by the dynamic control after the passing.
That is, patent documents 1 to 3 disclose no technical idea of controlling the molten metal temperature and the carbon concentration in the molten metal at the time of feeding the intermediate sublayers to be within a range that can easily bring the molten steel temperature and the molten steel composition at the time of stopping blowing to target values by the correction under dynamic control only at the time of feeding the intermediate sublayers.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a converter operation method in which a molten steel temperature and a molten steel composition at the time of stopping blowing are controlled to target values by using static control and dynamic control, and in which the molten metal temperature at the time of mid-gun charging can be controlled within a range in which the molten steel temperature and the molten steel composition at the time of stopping blowing can be brought to target values by correction under dynamic control. Further, a converter converting control system for performing the converter operating method is provided.
Means for solving the problems
The gist of the present invention for solving the above problems is as follows.
[1] In a method for operating a converter in which a sublance is charged into the converter during blowing of molten iron into the converter by blowing an oxidizing gas to decarburize the molten iron, a sublance measurement value including at least the molten metal temperature of the molten metal in the converter is measured, and the amount of oxygen to be supplied until the blowing is stopped and whether or not a cooling material or a heating material and the charge amount are charged are determined based on the measured sublance measurement value, whereby the temperature and the component concentration of the molten steel at the time of stopping the blowing are controlled to target values,
A target value of the molten metal temperature at the time of the sub-gun charging, that is, a target value of the intermediate temperature, is determined, and a timing for confirming a difference between the target value of the intermediate temperature and a predicted value of the intermediate temperature, which is a predicted value of the molten metal temperature at the time of the sub-gun charging, in converting before the time of the sub-gun charging is determined,
based on the operating conditions and measured values of the converter obtained at the start of the blowing and during the blowing, an estimated value of the temperature of the molten metal at the time of the progress of the blowing, that is, an estimated value of the temperature during the blowing and an estimated value of the carbon concentration in the molten metal, that is, an estimated value of the carbon concentration during the blowing,
and when the blowing is performed to the confirmation timing, calculating the intermediate temperature difference based on the in-blowing temperature estimation value and the in-blowing carbon concentration estimation value,
when the absolute value of the calculated intermediate temperature difference is greater than a preset threshold value, the cooling material or the heating material is charged into the converter during blowing after the confirmation timing and before charging into the sublance.
[2] The method of operating a converter according to the above [1], wherein the confirmation timing is determined based on the estimated value of the carbon concentration in the converting.
[3] The method of operating a converter according to the above [2], wherein the confirmation timing is determined in a range of 0.6 to 1.4 mass% of the estimated value of the carbon concentration during the blowing.
[4] The method for operating a converter according to any one of the above [1] to [3], wherein the predetermined threshold value is a value selected from values of 10 ℃ or higher.
[5] The method of operating a converter according to any one of [1] to [4], wherein when the absolute value of the intermediate temperature difference is greater than a preset threshold value, the amount of cooling material or the amount of heating material to be charged during the blowing after the confirmation timing and before charging into the sublance is determined based on 1 or 2 or more of the estimated value of the temperature during the blowing, the target value of the molten steel temperature at the time of stopping the blowing, and the amount of quicklime to be charged into the converter during the blowing.
[6] The method for operating a converter according to any one of the above [1] to [5], wherein the measurement values of the converter obtained at the start of blowing and during blowing include any one or both of measurement values obtained by an exhaust gas flow meter and an exhaust gas analyzer.
[7] The method of operating a converter according to any one of the above [1] to [6], wherein the measured value of the converter obtained at the start of blowing and during blowing is a measured value related to the optical characteristics of the mouth of the converter during blowing, including the rate of change in the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag.
[8] The method of operating a converter according to any one of the above [1] to [7], wherein the measured values of the converter obtained at the start of blowing and during blowing include a molten iron temperature measured using a non-contact optical method when molten iron used as a raw material for the blowing flows into the converter from a molten iron holding container.
[9] A blowing control system for a converter, comprising:
a sublance for measuring a measured value of a sublance including at least a molten metal temperature of a molten metal in a converter in blowing in which an oxidizing gas is blown into molten iron in the converter to decarburize and refine the molten iron;
a 1 st computer that sequentially estimates an estimated value of a temperature during blowing, which is an estimated value of a temperature of molten metal at a time of blowing and an estimated value of a carbon concentration in molten metal, which is an estimated value of a carbon concentration during blowing, based on operating conditions and measured values of a converter obtained at a start of blowing and during blowing, and calculates an amount of oxygen to be supplied for bringing a temperature and a component concentration of molten steel at a time of stopping blowing to target values, and whether or not a cooling material, a heating material, and an amount of charge are to be charged based on a sublance measured value measured by the sublance;
an operation control computer that controls an operation condition so that a molten steel temperature and a carbon concentration in molten steel at the time of stopping blowing become target values, based on the oxygen amount and the amount of the cooling material or the heating material calculated by the 1 st computer;
A 2 nd computer that sets a target value of the molten metal temperature at the time of the sub-gun charging, that is, a target value of the intermediate temperature, and sets a timing for confirming a difference between the target value of the intermediate temperature and a predicted value of the intermediate temperature, that is, a predicted value of the molten metal temperature at the time of the sub-gun charging, in converting before the time of the sub-gun charging,
the 2 nd computer calculates a midway temperature difference, which is a difference between the midway temperature target value and the midway temperature predicted value, and determines whether or not to perform the cooling material or the heating material in the converter during the blowing after the confirmation timing and before the sublance is put in, based on the calculated absolute value of the midway temperature difference; and
and a 3 rd computer for calculating the amount of the cooling material or the amount of the heating material to be charged when the cooling material or the heating material is charged.
[10] The blowing control system of a converter according to item [9] above, wherein an exhaust gas flow meter and an exhaust gas analyzer are provided in an exhaust gas treatment facility of the converter, data of the exhaust gas measured by the exhaust gas flow meter and the exhaust gas analyzer are transmitted from the exhaust gas flow meter and the exhaust gas analyzer to the 1 st computer, and the 1 st computer is configured to use the transmitted data of the exhaust gas for successive estimation of an estimated temperature during blowing and an estimated carbon concentration during blowing.
[11] The blowing control system of a converter according to the above [9] or [10], comprising: a spectroscopic camera arranged around the converter and shooting a burner flame from a gap between the converter and the movable cover; an image analysis device for removably recording image data transmitted from the spectroscopic camera and calculating the emission intensity of the image data at a wavelength ranging from 580 to 620nm,
the data of the emission intensity is transmitted from the image analysis device to the 1 st computer, and the 1 st computer is configured to use the transmitted data of the emission intensity for successive estimation of the temperature estimation value during blowing and the carbon concentration estimation value during blowing.
[12] The blowing control system of a converter according to any one of the above [9] to [11], comprising a temperature measuring device for optically measuring a temperature of molten iron used as a raw material for blowing by the converter during a period in which the molten iron is charged into the converter as a molten iron temperature at the time of charging, wherein data of a temperature measurement value of the temperature measuring device is transmitted from the temperature measuring device to the 1 st computer, and wherein the 1 st computer is configured to use the transmitted data of the temperature measurement value in a successive estimation of an in-blowing temperature estimation value and an in-blowing carbon concentration estimation value.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, in the converter operation method in which the molten steel temperature and the molten steel composition at the time of stopping blowing are controlled to the target values by using the static control and the dynamic control, the molten metal temperature at the time of feeding the sub-lance in the middle is controlled to be within the range in which the molten steel temperature and the molten steel composition at the time of stopping blowing can be brought to the target values by the correction under the dynamic control, and therefore, the molten steel temperature and the molten steel composition at the time of stopping blowing can be brought to the target values with high accuracy.
Drawings
Fig. 1 is a diagram showing an example of a flow chart of a blowing control system for performing a process of oxygen blowing in the embodiment of the present invention.
Fig. 2 is a schematic view of a converter facility equipped with a preferable converting control system in the practice of the present invention.
Fig. 3 is a schematic view of measuring the temperature of molten iron flowing from the molten iron holding vessel into the converter.
FIG. 4 is a graph showing the relationship between the temperature of molten metal and the concentration of carbon in molten metal at the time of charging the sublance in the middle of the present invention and the comparative example.
Fig. 5 is a graph showing an error between a target molten steel temperature at the time of stopping blowing and an actual molten steel temperature at the time of stopping blowing in examples of the present invention and comparative examples.
Detailed Description
Hereinafter, a method of operating a converter and a converting control system of the converter according to the present invention will be described.
In a converter operation for producing molten steel by decarburization refining of molten iron by oxygen blowing from a top-blowing lance, blowing control is performed in which static control and dynamic control are combined so that the molten steel component concentration such as the molten steel temperature and the carbon concentration at the time of stopping the oxygen blowing (at the end of the blowing) is controlled to be target values. In the method of operating a converter according to the invention, the converting is also controlled by a combination of static and dynamic control.
In the static control, a mathematical model based on the heat balance calculation and the mass balance calculation is used, and the amount of oxygen supplied and the amount of cooling material or heating material charged to control the molten steel temperature and the molten steel component concentration to target values are determined before the start of blowing. Then, the blowing is started based on the determined amount of oxygen supplied and the determined amount of cooling material or heating material to be charged, and after the blowing is continued for a certain period of time (for example, at the time of blowing 80 to 90% of the amount of oxygen supplied calculated by the static control, etc.), a sublance is charged into the furnace. Using the sublance, the temperature of the molten metal in the furnace, or both the temperature and the carbon concentration of the molten metal in the furnace, are measured. The sublance put into the converter during blowing is also referred to as a "midway sublance".
In the dynamic control, a sublance measurement value (molten metal temperature or both molten metal temperature and carbon concentration in molten metal) measured by a sublance and a mathematical expression model based on a thermal balance, a mass balance and a reaction model are used to correct the amount of oxygen supplied, the amount of cooling material or the amount of heating material to be charged determined by the static control, and finally the amount of oxygen supplied and the amount of cooling material or heating material to be charged until the blowing is stopped are determined.
The term "molten metal" as used herein means molten iron or molten steel. In decarburization refining, which is oxygen blowing in a converter for producing molten steel from molten iron, molten iron charged into the converter is changed into molten steel by decarburization. Since molten iron and molten steel are difficult to be distinguished from each other during oxygen blowing, molten iron and molten steel are collectively referred to as molten metal in this specification. When the distinction between molten iron and molten steel is clear, it is denoted as "molten iron" or "molten steel".
The calculation formula of the heat balance calculation in the static control is composed of, for example, an input heat determination term, a heat dissipation determination term, a cooling term or a temperature increase term, an error term, and a temperature correction term of the operator. The calculation formula of the oxygen supply amount (oxygen supply amount) includes, for example, a molten iron component, a sub-raw material input amount, a target molten steel temperature at the time of stopping blowing, and a target molten steel component.
However, since the static control is calculated based on information before the start of converting, when the post combustion rate and the yield of the secondary raw material change due to a change in the furnace conditions, the lance height, and a change in the oxygen supply amount, an error occurs in the static control. That is, the timing of the input of the sub-gun determined by the static control may be inaccurate. Accordingly, in patent document 2 and patent document 3, the information (exhaust gas) based on the converter exhaust gas (exhaust gasFlow rate, exhaust gas component) and spectroscopic information of the furnace mouth, the carbon concentration of the molten metal during blowing is successively estimated, and the sublance is put in the middle at the timing when the decarburization oxygen efficiency starts to decrease. Here, "decarburization oxygen efficiency" means a ratio of oxygen contributing to a decarburization reaction among oxygen supplied into the furnace, and "lance height" means a distance from a tip end of the top-blown lance to a stationary bath surface of molten iron in the converter. In addition, "post combustion" means that CO gas generated in the furnace by the decarburization reaction is burned into CO by oxygen supplied from a top-blowing lance 2 Gas phenomenon.
However, in order to control the temperature of molten steel and the carbon concentration in molten steel within the target range when blowing is stopped, it is not sufficient to perform only control using estimation of the carbon concentration transition during blowing.
As a result of intensive studies, the inventors of the present application have found that there is a deviation in the molten metal temperature at the time of the sub-gun input in the middle of the process, as a cause of no improvement in the accuracy of controlling the molten steel temperature at the time of stopping blowing. In particular, it was found that, when the timing of the input of the intermediate sublayers, which is determined by the timing of the start of the decrease in decarburization oxygen efficiency and is obtained by the successive estimation of the carbon concentration in the molten metal, is greatly deviated from the timing of the input of the intermediate sublayers, which is determined by the static control, the deviation of the molten metal temperature at the time of the input of the intermediate sublayers becomes large.
The reason for this deviation in the time of the sub-gun input is considered that the deviation in the ratio of the oxygen to be injected, for example, for post combustion or iron combustion in the molten metal, which is not used for the reaction with the components or sub-raw materials in the molten metal estimated by the static control, is a cause of the deviation. However, it is difficult to reflect these deviations to static control with high accuracy.
Accordingly, the inventors of the present application considered that not only the carbon concentration of the molten metal during blowing but also the temperature of the molten metal may be estimated successively, and that the operation (action, operation) of adjusting the temperature of the molten metal may be performed before the sub-gun is put in the middle by using the successively estimated value of the temperature of the molten metal so that the temperature of the molten metal at the time of putting in the middle is within a range that can be corrected by dynamic control.
The method described in patent document 2 and patent document 3 can be applied to the successive estimation of the carbon concentration of the molten metal in the present invention. That is, the carbon concentration in the molten metal is estimated based on the measurement results of the temperature and the component concentration of the molten metal before the start of the blowing or at least one of the blowing, the information on the flow rate and the component concentration of the exhaust gas, the information on the optical characteristics of the mouth of the converter (the actual conditions of the mouth spectroscopic system and the information on the optical characteristics of the mouth), the information on the oxygen supply amount and the oxygen supply speed, the information on the flow rate of the stirring gas, the information on the amount of the raw materials (main raw material and sub-raw material) charged, and the like. Here, as information related to the optical characteristics of the furnace mouth of the converter, for example, information of measuring the emission spectrum of the furnace mouth combustion flame or the emission spectrum of the tap hole combustion flame emitted from the furnace mouth of the converter, and calculating the temporal change in the emission intensity of the wavelength in the range of 580 to 620nm of the measured emission spectrum can be used.
The successive estimation of the molten metal temperature in the present invention is performed as follows. First, the oxygen input amount such as the oxygen-fed amount and the input amount of iron oxide, and the flow rate and the exhaust gas composition (CO gas concentration, CO 2 Concentration of gas, O 2 Gas concentration, etc.), the oxygen amount used for combustion of carbon in the molten metal is obtained by performing correction calculation so as to minimize the oxygen balance in the furnace. Then, the carbon concentration in the molten metal is estimated from the carbon amount in the burned molten metal. At this time, the calculated change in the carbon concentration is converted into reaction heat, and the molten metal temperature is estimated.
Further, in the estimation calculation of the molten metal temperature, not only carbon of the molten iron component but also the heat of reaction of silicon, manganese, phosphorus, iron and oxygen of the molten iron component, and also the heat absorption of scrap iron and sub-raw materials, the sensible heat of gas according to the flow rate of exhaust gas, and the heat release according to the temperature of the iron scale of the converter are used as calculation items. The reaction heat is corrected by multiplying the coefficient determined by the regressive according to the past operation result so as to minimize the error between the measured value of the molten metal temperature of the intermediate sublance and the calculated molten metal temperature.
The error between the molten metal temperature at the time of feeding the intermediate sublance at the time of starting the decrease in decarburization oxygen efficiency and the estimated molten metal temperature at the time of feeding the intermediate sublance calculated by the conventional static control was 19.6 ℃ in terms of the standard deviation 1σ. In contrast, the temperature error between the molten metal temperature at the time of feeding the intermediate sublance at the time of starting the decrease in decarburization oxygen efficiency and the estimated molten metal temperature at the time of feeding the intermediate sublance obtained by successive calculation of the molten metal temperature was expressed as 14.4 ℃. That is, the timing of the input of the intermediate sub-gun is determined by successively calculating the molten metal temperature, thereby improving the accuracy of temperature estimation at the time of the input of the intermediate sub-gun.
For example, when the raw unit of quicklime in the furnace is 5 to 15 kg/ton of molten iron, the target molten steel temperature.+ -. 10 ℃ and the target carbon concentration.+ -. 0.015 mass% are set as the molten steel temperature and the carbon concentration in the molten steel at the time of stopping blowing. In this case, it was confirmed that if the carbon concentration in the molten metal at the time of the intermediate sublance input was 0.1 to 0.3 mass%, and the molten metal temperature at the time of the intermediate sublance input was in the range of "target temperature at the time of stopping blowing-35 ℃ to" target temperature at the time of stopping blowing-65 ℃, the simultaneous achievement rate of the molten steel temperature at the time of stopping blowing and the carbon concentration in the molten steel was high (88%).
In the present invention, the carbon concentration in the molten metal at the time of the intermediate sublance charging and the molten metal temperature at the time of the intermediate sublance charging are set within the above ranges.
Next, an example of the embodiment of the present invention will be described in terms of the oxygen blowing process. Fig. 1 shows an example of a flow chart of a blowing control system according to the oxygen blowing process.
First, molten iron conditions such as the temperature of molten iron, the amount of molten iron charged, and the composition of molten iron to be used or used for the blowing are obtained (S-1).
Next, in the converting, the following 2 points are determined (S-2). The timing to be determined may be any timing before the timing to be determined in the following (2), but is preferably determined before the time reaches about 1/2 of the predetermined converting time, more preferably before the start of converting, from the viewpoint of having a sufficient time.
(1) Setting of intermediate temperature target value
The "intermediate temperature target value" refers to a target value of the molten metal temperature at the time of the input of the intermediate sublance.
(2) Confirming the setting of the time;
the "confirmation timing" refers to a timing (timing or moment) at which a difference between a target value of the molten metal temperature in the casting period of the intermediate sublance, that is, a "intermediate temperature target value", and a predicted value of the molten metal temperature in the casting period of the sublance, that is, a "intermediate temperature difference", is confirmed in a period before the casting of the intermediate sublance in blowing.
The "intermediate temperature target value" is preferably determined in consideration of the target molten steel temperature and the slag amount in the furnace when the blowing is stopped. For example, as in the following formula (1), it is preferable that the primary formula of the target molten steel temperature at the time of stopping the blowing and the polynomial formula of the raw quicklime unit to be charged into the furnace during the blowing are combined and obtained. The formula (1) is a combination of a polynomial of a prescribed charged quicklime raw unit, and the polynomial of the prescribed charged quicklime raw unit may be replaced with a polynomial of a prescribed slag amount in the furnace based on the prescribed charged quicklime raw unit.
Target intermediate temperature (c) =target molten steel temperature for stopping blowing (c) -a×w-b×w 2 －c···(1)
Here, W is the raw lime unit (kg/molten iron-ton) during the blowing, a (DEG C. Times.molten iron-ton/kg), b (DEG C. Times.molten iron-ton) 2 /kg 2 ) C (. Degree. C.) is a coefficient. The coefficient a, the coefficient b, and the coefficient c are set by using regression calculation based on the past operation result so that the standard reaching rate is the highest when the blowing is stopped.
The confirmation timing is determined from the successive estimated value of the carbon concentration in the molten metal, for example, as the timing at which the estimated value of the carbon concentration in the molten metal calculated successively during blowing reaches 1.0 mass%. In particular, it is preferable to determine the timing at which the successive estimated value of the carbon concentration in the molten metal is in the range of 0.6 to 1.4 mass% as the confirmation timing.
When a timing at which the successively estimated value of the carbon concentration in the molten metal exceeds 1.4 mass% is determined as a confirmation timing, the confirmation timing is too early to cope with a change in the subsequent converting conditions. On the other hand, when the timing at which the successively estimated value of the carbon concentration in the molten metal is less than 0.6 mass% is determined as the confirmation timing, the confirmation timing is too late, and there is a possibility that measurement is performed by the intermediate sublayers before all the auxiliary materials (the cooling material and the heating material) charged in the period from the confirmation timing to the intermediate sublayers are reacted, and therefore, there is a possibility that the accuracy of dynamic control performed later is lowered.
In converting after the start of converting, exhaust gas information such as the flow rate and the components of the converter exhaust gas is acquired successively. At the same time, oxygen supply information (S-3) of the oxygen supply amount and the oxygen supply speed from the top-blowing lance is also successively acquired.
In addition, in the blowing after the start of the blowing, a mathematical expression model based on the heat balance calculation and the mass balance calculation is used, and based on the operating conditions and the measured values of the converter obtained at the start of the blowing and during the blowing obtained in the step (S-1) and the step (S-3), the "estimated value of the temperature during the blowing" which is the estimated value of the temperature of the molten metal at the time of the progress of the blowing, and the "estimated value of the carbon concentration during the blowing" which is the estimated value of the carbon concentration during the blowing are estimated successively (S-4).
As the blowing proceeds, the decarburization reaction proceeds, and the estimated value of the carbon concentration in the blowing calculated successively reaches a "confirmation timing" in the range of 0.6 to 1.4 mass% (S-5). If blowing is performed at the confirmation timing, a "midway temperature predicted value" which is a predicted value of the molten metal temperature at the time of the sublance input is calculated. The "predicted intermediate temperature value" determines the timing of confirmation from the successive estimated value of the carbon concentration in the molten metal, and the value of the carbon concentration, that is, the "estimated value of the carbon concentration during blowing" is defined as C x When (mass%) is calculated, the following expression (2) is used.
Predicted value of intermediate temperature (degree C) =t (C x )+d×(C x －C SL )···(2)
Here, T (C x ) Is' pushing carbon concentration in convertingThe constant value is C x (mass%) time "temperature estimate during blowing" (. Degree.C.), C x C is the "estimated value of carbon concentration in converting" (mass%) at the timing of confirmation SL The concentration of carbon (mass%) at the middle of the gun is set to a predetermined level. d is a rate of rise in the temperature of the molten metal (c/mass%) when 1.0 mass% of carbon in the molten metal is burned, and is preferably a value obtained by regressive using the results of conventional converter blowing.
That is, as shown in the above formula (2), the "intermediate temperature predicted value" is obtained from the "during-blowing temperature estimated value" and the "during-blowing carbon concentration estimated value".
Then, the "intermediate temperature difference" is calculated using the "intermediate temperature target value" thus obtained and the "intermediate temperature predicted value" thus obtained (S-6).
Since the "intermediate temperature target value" is represented by the formula (1) and the "intermediate temperature predicted value" is represented by the formula (2), the difference between the "intermediate temperature predicted value" and the "intermediate temperature target value" at the time of the intermediate sub-gun delivery, that is, the "intermediate temperature difference", is represented by the following formula (3) according to the formulas (1) and (2).
Intermediate temperature difference (C) =intermediate temperature predicted value (C) -intermediate temperature target value (C) =t (C) x )+d×(C x －C SL ) - [ stop blowing target molten steel temperature (. Degree.C.) -a-W-b-W ] 2 －c]···(3)
When the "intermediate temperature difference" calculated by the expression (3) exceeds 0 (zero), the "intermediate temperature predicted value" is higher than the "intermediate temperature target value", and when the "intermediate temperature difference" is smaller than 0 (zero), the "intermediate temperature predicted value" is lower than the "intermediate temperature target value".
Therefore, no matter whether the "intermediate temperature difference" is a positive number or a negative number, an operation (action, operation) of correcting the molten metal temperature is required when the absolute value of the "intermediate temperature difference" is large. That is, when the absolute value of the "intermediate temperature difference" is larger than the predetermined threshold value, it is necessary to take an action of bringing the "intermediate temperature predicted value" after the action closer to the "intermediate temperature target value".
Therefore, it is determined whether or not the "intermediate temperature difference" is greater than a predetermined threshold (positive number) (S-7). When the "intermediate temperature difference" exceeds the threshold value (positive number) by a positive number, a cooling material is charged for lowering the molten metal temperature (S-8).
When the "intermediate temperature difference" is equal to or smaller than a predetermined threshold (positive number), it is determined whether or not the "intermediate temperature difference" is smaller than the threshold (negative number) (S-9). When the "intermediate temperature difference" is negative and smaller than the threshold value (negative), a temperature increasing material is charged for increasing the molten metal temperature (S-10).
When the absolute value of the "intermediate temperature difference" is equal to or less than a predetermined threshold value, an operation for adjusting the temperature of the molten metal is not performed.
For example, if the predetermined threshold is set to 15 ℃, when the "intermediate temperature difference" exceeds +15 ℃, the cooling material such as scale or iron ore is charged into the furnace to cool the molten metal so that the "intermediate temperature predicted value" after the operation is lowered and approaches the "intermediate temperature target value". The amount of the cooling material to be charged is determined by multiplying the "intermediate temperature difference" by the cooling coefficient. On the other hand, when the "intermediate temperature difference" is smaller than, for example, -15 ℃, a temperature-increasing material such as a carbon material (the temperature is increased by combustion of carbon contained therein) or an fe—si alloy (the temperature is increased by combustion of silicon (Si) contained therein) is charged into the furnace so that the "intermediate temperature predicted value" after the operation increases and approaches the "intermediate temperature target value", and the temperature of the molten metal is increased. The amount of the heating material to be charged is determined by multiplying the "intermediate temperature difference" by the heating coefficient.
The threshold value that is predetermined as the absolute value of the "intermediate temperature difference" may be appropriately determined in accordance with the individual steel-making plant, but is preferably a value selected from values of 10 ℃ or higher. For example, 15 ℃.
If the absolute value of the "intermediate temperature difference" is less than 10 ℃, the correction can be performed by dynamic control even if the cooling material or the heating material is not charged into the converter during the blowing after the confirmation timing and before the charging into the sublance. Therefore, the predetermined threshold value may be 10℃or higher. In addition, in the case where the absolute value of the "intermediate temperature difference" is larger, in the blowing after the confirmation timing and before the sublance is put into operation, the amount of cooling material to be put into the converter or the amount of heating material to be put into the converter is increased, so that the amount of correction under dynamic control becomes smaller, and the molten steel temperature and the molten steel composition at the time of stopping the blowing can be easily brought to the target values, and therefore, it is not necessary to determine the upper limit of the absolute value.
Then, a timing at which the decarburization efficiency starts to decrease (as described later, a timing at which the "estimated value of the carbon concentration during blowing" is about 0.45 mass%) is determined based on the "estimated value of the carbon concentration during blowing", which is a successive estimated value of the carbon concentration in the molten metal, and the sublance is put in the middle of the timing.
After the intermediate sublance is put in, dynamic control is performed based on the sublance measurement value measured by the intermediate sublance, and an operation indicated by the dynamic control is performed to terminate the oxygen blowing.
By performing the above operation, the control of the molten metal temperature at the time of the sub-gun feeding in the middle becomes easier than in the prior art, and the molten metal temperature at the time of stopping blowing can be controlled to the target value with high accuracy by the dynamic control thereafter.
In the embodiment of the present invention, the point for further exhibiting 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 value of the converter obtained at the start of blowing and during blowing, it is preferable to use the measurement value of the exhaust gas flow rate of the exhaust gas flow meter provided in the flue of the exhaust gas treatment device of the converter and the measurement value of the exhaust gas component (CO gas concentration, CO 2 Gas concentration, O2 gas concentration, etc.). Further, it is preferable to use these in combination, and to use other measurement values useful for the successive estimation of the "temperature estimation during blowing" and the "carbon concentration estimation during blowing".
For example, as the measurement value of the converter to be used, a measurement value of the optical characteristic of the converter mouth during converting, that is, the rate of change of the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in slag is preferably used. By using this value, the accuracy of successive estimation of the carbon concentration in the molten metal during blowing is improved. Specifically, as the optical characteristics of the converter mouth, the maximum value of the emission intensity in a wavelength band (spectrum) such as a wavelength 550 to 650nm of light emitted in a wavelength band (spectrum) associated with the decarburization reaction is detected by the reduction reaction of iron oxide in slag represented by the following reaction formula (4), and the measured value is used.
FeO +C→Fe+CO· · · (4)
When the carbon concentration in the molten metal reaches a value near the critical carbon concentration by oxygen decarburization, the efficiency of the decarburization reaction (decarburization oxygen efficiency) represented by the formula (4) is lowered, and the emission intensity at a wavelength of 550 to 650nm is also lowered. Here, the "critical carbon concentration" refers to the carbon concentration in the molten metal at the boundary where the decarburization reaction rate of the oxygen-fed decarburization moves from a state where the rate is determined by the oxygen supply rate to a state where the rate is determined by the carbon movement (diffusion) in the molten metal. In other words, the "critical carbon concentration" is the carbon concentration in the molten metal at the time when the decarburization oxygen efficiency starts to decrease. The critical carbon concentration varies according to 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 about 0.45 mass%.
Therefore, in the embodiment of the present invention, it is preferable that the change rate of the emission intensity of the maximum value of the emission intensities in the above-mentioned wavelength band is calculated and reflected in the successive estimation of the carbon concentration in the molten metal during blowing. For example, the timing at which the change rate of the emission intensity changes from a positive value to a negative value may be detected as the timing at which the carbon concentration in the molten metal reaches the critical carbon concentration.
For example, the measured value preferably includes a temperature of molten iron measured by a non-contact optical method when the molten iron used as a raw material for the blowing flows from the molten iron holding vessel into the converter. By using this value, the accuracy of successive estimation of the "temperature estimation value during blowing" is improved.
Specifically, as the initial value of the "temperature estimate during blowing", a value determined based on the temperature of molten iron measured when flowing from the molten iron holding container into the converter is preferably used. Generally, as the initial value, a temperature measured by immersing a thermocouple in molten iron filled in a molten iron holding vessel before charging into a converter is used. However, since the temperature of the molten iron in the molten iron holding vessel decreases in the period from the measurement of the temperature of the molten iron in the molten iron holding vessel to the charging of the molten iron into the converter, the amount of decrease varies depending on the charging, and thus the accurate temperature of the molten iron is not reflected as an initial value. Therefore, it is preferable to measure the temperature of the molten iron during the period in which the molten iron is charged into the converter, and to use a value determined based on the temperature as an initial value of the "estimated temperature during blowing". The initial value of the "temperature estimated value during blowing" may be a value obtained by directly using the temperature of molten iron measured when the molten iron flows into the converter from the molten iron holding vessel, or a value obtained by correcting the temperature of molten iron measured when the molten iron flows into the converter from the molten iron holding vessel in consideration of the time from tapping of the previous charge to the charging of the molten iron at that time, that is, the empty time, the amount of iron pieces charged, and the like.
The measurement of the temperature of molten iron when the molten iron flows from the molten iron holding vessel into the converter is performed using a non-contact optical method. As the optical method, a so-called 2-color thermometer is preferably used, which measures the emission spectrum emitted from the molten iron and calculates the temperature of the molten iron from the ratio of the radiant energy of different 2 wavelengths selected from the measured emission spectra. This is because, by using a 2-color thermometer as a temperature measuring device for optically measuring the temperature of molten iron, even when the emissivity of the object to be measured varies, the ratio of the 2 spectral emissivity depends only on the temperature and can be accurately measured without depending on the variation of the emissivity, as long as the relationship of the 2 spectral emissivity having different wavelengths varies while maintaining a proportional relationship.
Here, when different 2 wavelengths used in the 2-color thermometer are set to λ1 and λ2 (λ2> λ1), it is preferable that both λ1 and λ2 are in the range of 400nm to 1000 nm. In the case where λ1 and λ2 are smaller than 400nm, it is difficult to detect the radiant energy with a usual spectroscopic camera because of the short wavelength. On the other hand, when λ1 and λ2 exceed 1000nm, the influence of the change in emissivity ratio becomes large because the wavelength is long. The absolute value of the difference between λ1 and λ2 is preferably 50nm to 600 nm. When the absolute value of the difference between λ1 and λ2 is smaller than 50nm, the wavelengths of λ1 and λ2 are close to each other, so that it is difficult to perform light splitting with a normal light splitting camera, which is not preferable. On the other hand, when the absolute value of the difference between λ1 and λ2 exceeds 600nm, one wavelength (λ2) is inevitably selected from the long wavelength range, and the influence of the emissivity ratio fluctuation becomes large due to the long wavelength, which is not preferable.
When the temperature of molten iron, which is measured by a non-contact optical method when molten iron, which is used as a raw material for converting, flows into a converter from a molten iron holding vessel, is used as an initial value of an "in-process temperature estimate value", a temperature error between a molten metal temperature at the time of feeding the intermediate sublance at the time of starting a decrease in decarburization oxygen efficiency and the "in-process temperature estimate value" at the time of feeding the intermediate sublance, which is obtained by successive calculation of the molten metal temperature, is reduced to 12.9 ℃ in terms of a standard deviation 1 sigma. That is, by using a value determined based on the temperature of molten iron measured by a non-contact optical method at the time of flowing into the converter as an initial value of the "during-blowing temperature estimation value", the accuracy of temperature estimation at the time of mid-gun introduction is further improved.
In the case where the measured value of the converter to be used includes both the measured value of the optical characteristic of the converter mouth during converting (the change rate of the luminous intensity of the spectrum due to the reduction reaction of the iron oxide in the slag) and the molten iron temperature measured when the molten iron used as the raw material for the converting flows into the converter from the molten iron holding container, either measurement may be handled by a spectroscopic camera. That is, both can be measured by 1 spectroscopic camera. Here, the spectroscopic camera is generally a general term for a camera that can capture spectroscopic data in addition to a planar image of a measured temperature such as a thermal imager. The spectroscopic data is data obtained by collecting a plurality of wavelengths included in the emitted light separately for each wavelength.
Hereinafter, a description will be given of a structure of a converter plant including a preferable converting control system in terms of a method of operating a converter according to the present invention with reference to the accompanying drawings. Fig. 2 shows a schematic view of a converter plant preferred in the practice of the invention.
The converter plant 1 preferred in the practice of the present invention comprises a converter 2; a top-blowing lance 3; a bottom blowing port 4; a sub-gun 5; a spectroscopic camera 7 disposed around the converter 2 and capable of capturing a furnace mouth combustion flame 18; an image analysis device 8 for removably recording the photographed image photographed by the spectroscopic camera 7 and analyzing the photographed image; a 1 st computer 9 for inputting the data analyzed by the image analyzer 8; an operation control computer 12 for inputting the data analyzed by the 1 st computer 9.
Further, the computer system includes a 2 nd computer 10 for inputting data analyzed by the 1 st computer 9, and a 3 rd computer 11 for inputting data analyzed by the 2 nd computer 10. The data analyzed by the 2 nd computer 10 and the data analyzed by the 3 rd computer 11 are input to the operation control computer 12. The 1 st computer 9, the 2 nd computer 10, and the 3 rd computer 11 may be 1 computer. The operation control computer 12 transmits a control signal based on the data input from the 1 st computer 9 and the 3 rd computer 11.
Further, the gun height control device 13, the sub-gun elevation control device 14, the oxidizing gas flow control device 15, the bottom-blown gas flow control device 16, and the sub-raw material charging control device 17 are configured to be individually operable in response to a control signal transmitted from the operation control computer 12. The lance height control device 13 is a device for adjusting the lance height of the top-blowing lance 3, and the sub-lance elevation control device 14 is a device for controlling the lowering and the raising of the sub-lance 5. The oxidizing gas flow rate control device 15 is a device for adjusting and measuring the flow rate of the oxidizing gas injected from the top-blowing lance 3. The bottom blowing gas flow rate control device 16 is a device for adjusting the flow rate of the stirring gas blown in from the bottom blowing port 4, and the auxiliary raw material charging control device 17 is a device for controlling the type and charging amount of the auxiliary raw material stored in the furnace charging hopper 24.
For feedback control, the actual values are input from these control devices to the operation control computer 12. The secondary raw material is a generic term for a medium such as quicklime, a coolant such as iron ore, and a heating material such as a carbon material. The main raw materials are molten iron and scrap iron relative to the auxiliary raw materials.
Further, an exhaust gas flow meter 22 for measuring the flow rate of the exhaust gas discharged from the converter 2 and a device for analyzing the composition of the exhaust gas (CO gas, CO 2 Gas, O 2 Gas, etc.) gas analyzer 23. The measured values of the exhaust gas flowmeter 22 and the gas analyzer 23 are input to the 1 st computer 9.
The converter 2 used in the present invention is configured such that the oxidizing gas jet 19 is injected from the top-blowing lance 3 into the molten iron 6 in the furnace and the stirring gas is blown from the bottom blowing port 4 in the bottom of the furnace. As the oxidizing gas discharged from the top-blowing lance 3, pure oxygen (industrial pure oxygen) or a mixed gas of oxygen and an inert gas is used. Pure oxygen is generally used as the oxidizing gas.
Data such as the composition (C, si, mn, P, S and the like) of the molten iron 6 used for the blowing (charging), the temperature, the mass (charging amount) of the scrap iron during the blowing, and the like are input from a converter process computer (not shown) to the 1 st computer 9. Further, a sub-gun measurement value of the sub-gun 5, that is, a measurement value of the molten metal temperature, or a measurement value of both the molten metal temperature and the carbon concentration in the molten metal is input to the 1 st computer 9. Then, a target value of the molten steel temperature and a target value of the molten steel component concentration such as the carbon concentration at the time of stopping the oxygen blowing (at the end) are input from the converter process computer to the 1 st computer 9. The target value of the molten steel temperature and the target value of the molten steel component concentration such as the carbon concentration at the time of stopping the oxygen blowing may be directly set in the 1 st computer 9.
Before the start of blowing, the 1 st computer 9 performs static control using a mathematical model based on a heat balance calculation and a mass balance calculation based on the inputted target value of the molten steel temperature and the target value of the molten steel component concentration at the time of stopping blowing, and the inputted composition, temperature, mass, and mass of the molten iron 6. The 1 st computer 9 calculates, as data for static control, an amount of oxygen supplied, an amount of medium solvent charged, and an amount of cooling material or heating material charged, which are required to control the molten steel temperature and the molten steel component concentration at target values at the time of stopping blowing. That is, the 1 st computer 9 performs static control before the start of converting.
The data of the static control by the 1 st computer 9 is input to the operation control computer 12. The operation control computer 12 transmits 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 raw material charging control device 17, respectively, based on the data of the static control input from the 1 st computer 9, so that the molten steel temperature and the molten steel component concentration at the time of stopping the blowing become target values. In this way, blowing based on static control is started.
The 1 st computer 9 uses a mathematical model based on heat balance calculation and mass balance calculation in the blowing after the start of the blowing, and successively estimates "in-blowing temperature estimated value" and "in-blowing carbon concentration estimated value" which are successively estimated values of the molten metal temperature at each time point when the blowing is performed based on the operation conditions and measured values of the converter obtained at the start of the blowing and during the blowing.
As a method of successively estimating the "estimated value of the carbon concentration during blowing", for example, the mass balance calculation of carbon and oxygen during the decarburization reaction is performed using the supply amount of the oxidizing gas inputted from the oxidizing gas flow rate control device 15, the carbon concentration of the molten iron 6 before oxygen blowing inputted from the converter process computer, the measured value of the exhaust gas flow rate inputted from the exhaust gas flow meter 22, and the measured value of the exhaust gas composition inputted from the gas analyzer 23, and the carbon concentration of the molten metal in the furnace is estimated.
The 2 nd computer 10 sets the aforementioned "intermediate temperature target value" and "confirmation timing". The "intermediate temperature target value" which is the target value of the molten metal temperature at the intermediate sub-gun charging time is calculated using the above equation (1). The set time period may be any time before the "confirmation timing", but is preferably determined before about 1/2 of the predetermined converting time is performed, and more preferably is determined before the start of converting.
Here, as described above, the "confirmation timing" refers to a timing at which the "intermediate temperature difference" is confirmed between the "intermediate temperature target value" and the "intermediate temperature predicted value" which is the predicted value of the molten metal temperature in the time period of the casting of the sublayers, that is, the "intermediate temperature difference", at a time period before the casting of the sublayers in the process of blowing. The confirmation timing is preferably determined to be a timing at which the "estimated value of carbon concentration during blowing" of the successive estimated values obtained by the 1 st computer 9 is in the range of 0.6 to 1.4 mass%.
After the blowing is performed and the "estimated value of carbon concentration during blowing" calculated successively by the 1 st computer 9 is performed to the "confirmation timing", the 1 st computer 9 inputs a signal of the "estimated value of carbon concentration during blowing" to the 2 nd computer 10. If the "confirmation timing" is input from the 1 st computer 9, the 2 nd computer 10 calculates the "intermediate temperature predicted value" using the aforementioned equation (2). Then, using the calculated "intermediate temperature predicted value" and the calculated "intermediate temperature target value", the "intermediate temperature difference" is calculated by the above formula (3).
Based on the absolute value of the "intermediate temperature difference" obtained, the 2 nd computer 10 determines whether or not to charge the cooling material or the heating material into the converter during the blowing before the sublance charge. Specifically, for example, the threshold value of the absolute value of the "intermediate temperature difference" is set to 15 ℃, and when the "intermediate temperature difference" exceeds +15 ℃, it is determined that a cooling material such as an oxide scale or iron ore is charged into the furnace, whereas when the "intermediate temperature difference" is smaller than-15 ℃, it is determined that a heating material such as a carbon material or an fe—si alloy is charged into the furnace. In this case, if the absolute value of the "intermediate temperature difference" is 15 ℃ or less, the cooling material and the heating material are not added. When the "intermediate temperature difference" exceeds a positive number of +15 ℃, the cooling material is charged, and when the "intermediate temperature difference" exceeds a negative number of-15 ℃, the heating material is charged, so that the absolute value of the "intermediate temperature difference" at the time of charging the subsequent sublance becomes smaller. That is, by adding the cooling material or the heating material, the difference between the target value of the intermediate temperature and the predicted value of the intermediate temperature at the time of adding the sub-gun becomes small. The 2 nd computer 10 transmits the presence or absence of the input of the cooling material or the heating material to the 3 rd computer 11 and the operation control computer 12.
If a signal indicating the addition of the cooling material or the heating material is input from the 2 nd computer 10, the 3 rd computer 11 calculates the addition amount of the cooling material or the addition amount of the heating material. The amount of the cooling material and the heating material to be charged is calculated based on the absolute value of the "intermediate temperature difference". For example, if the cooling material is iron ore, 2.7 kg/iron-ton of the cooling material of the original unit is charged when the "intermediate temperature difference" exceeds +15 ℃ and +20 ℃, 3.6 kg/iron-ton of the cooling material of the original unit is charged when the "intermediate temperature difference" exceeds +20 ℃ and +25 ℃, and the amount of the cooling material charged is increased as the "intermediate temperature difference" is larger when the "intermediate temperature difference" is positive. On the other hand, when the "intermediate temperature difference" is negative, the larger the absolute value of the "intermediate temperature difference", the larger the amount of the heating material to be charged.
The calculated amount of the cooling material and the calculated amount of the heating material to be charged are transmitted from the 3 rd computer 11 to the operation control computer 12. The operation control computer 12, which receives the signals of the amounts of the cooling material and the heating material to be charged from the 3 rd computer 11, transmits a control signal to the auxiliary raw material charging control device 17 so as to charge a predetermined amount of the cooling material or the heating material into the furnace. The auxiliary raw material charging control device 17 that receives the control signal charges a predetermined amount of cooling material or heating material into the furnace.
Then, if the "estimated value of carbon concentration during blowing" calculated successively by the 1 st computer 9 reaches the carbon concentration (about 0.45 mass%) at which the decarburization oxygen efficiency starts to decrease, the 1 st computer 9 sends the signal to the operation control computer 12. The operation control computer 12 that has received this signal transmits a control signal for inputting the sub-gun to the sub-gun elevation control apparatus 14. The sublance lifting control device 14 that receives the control signal inputs the sublance 5 into the furnace.
The sublance 5 measures the molten metal temperature, or both the molten metal temperature and the carbon concentration in the molten metal. Here, the molten metal temperature is measured by a thermocouple provided in a sublance probe at the tip of the sublance 5. The carbon concentration in the molten metal is obtained from a cooling curve of the molten metal collected by the molten metal sampler in the sub-gun when the molten metal is solidified in the molten metal sampler. The sub-gun measurement value of the sub-gun 5, that is, the measurement value of the molten metal temperature, or the measurement value of both the molten metal temperature and the carbon concentration in the molten metal is sent to the 1 st computer 9.
The 1 st computer 9 calculates the amount of oxygen to be supplied to achieve the target values of the temperature and the component concentration of the molten steel at the time of stopping blowing, and whether or not the cooling material, the heating material, and the amount of charge need to be charged, based on the measured values of the sublayers measured by the sublayers 5. That is, the 1 st computer 9 performs dynamic control after the sublance is put in.
The 1 st computer 9 transmits a signal for dynamic control to the operation control computer 12. The operation control computer 12, which receives the signal of the dynamic control of the 1 st computer 9, transmits a control signal to the oxidizing gas flow rate control device 15 so as to supply a predetermined amount of oxidizing gas into the furnace. At the same time, a control signal is sent to the auxiliary raw material charging control device 17 to charge a predetermined amount of cooling material or heating material into the furnace. The oxidizing gas flow rate control device 15 that receives the control signal supplies a predetermined amount of oxygen into the furnace. The auxiliary-raw-material-charging control device 17, which receives a control signal from the operation control computer 12, charges a predetermined amount of cooling material or heating material into the furnace.
If the supply of the oxygen amount and the feeding of the cooling material or the heating material based on the dynamic control of the 1 st computer 9 are completed, the oxygen blowing is ended.
With the blowing control system having the above-described configuration, the temperature of the molten metal at the time of the input of the sub-gun in the middle is easier to control than in the prior art, and the temperature of the molten metal at the time of stopping the blowing can be controlled to the target value with high accuracy by the dynamic control thereafter.
In the present invention, in order to more accurately perform the successive estimation of the "during-blowing temperature estimation value" and the "during-blowing carbon concentration estimation value", as described above, as the measurement value of the converter obtained at the start of the blowing and during the blowing, it is preferable to use a measurement value of the optical characteristics of the mouth of the converter during the blowing and/or a measurement value of the temperature of the molten iron measured by a non-contact optical method when the molten iron flows from the molten iron holding container into the converter.
In the converter equipment 1 used in the present invention, a spectroscopic camera 7 is provided as shown in fig. 2 in order to measure a measured value of an optical characteristic of a converter mouth and a measured value of a temperature of molten iron measured by a non-contact optical method. In fig. 2, reference numeral 25 denotes a charging chute for the auxiliary raw material, reference numeral 26 denotes an oxidizing gas supply pipe of the top-blown lance, reference numeral 27 denotes a cooling water supply pipe of the top-blown lance, and reference numeral 28 denotes a cooling water discharge pipe of the top-blown lance.
Around the converter 2, a spectroscopic camera 7 is mounted at a position where the emission spectrum of the burner flame 18 of the converter can be measured. The furnace mouth combustion flame 18, which is seen from the gap between the furnace mouth 20 and the movable cover 21 of the converter, is captured by the attached spectroscopic camera 7. The captured image (image data) captured by the spectroscopic camera 7 is sequentially sent to the image analysis device 8. The image analysis device 8 records the transmitted captured image (image data), and performs line analysis on any scanning line of the image data to analyze the emission wavelength and the emission intensity for each wavelength.
The image data of the analyzed burner flame 18 is transmitted to the 1 st computer 9 each time. The 1 st computer 9 successively estimates the "estimated value of the carbon concentration during blowing" by using the analysis image data of the emission spectrum of the burner flame 18 inputted from the image analysis device 8 at the time of successively estimating the "estimated value of the carbon concentration during blowing" by the mass balance calculation of oxygen and carbon. This improves the estimation accuracy of the "estimated value of the carbon concentration during blowing".
The "furnace mouth combustion flame" herein means a flame in the furnace blown out from the furnace mouth 20 of the converter 2 to the upper flue 29. The emission spectrum of the burner flame 18 contains CO gas and CO generated by the decarburization reaction in the converter 2 Information on gas, information on FeO (intermediate product) of iron atoms evaporated from a fire in the furnace, and information on CO 2 The gas is generated by spontaneous combustion caused by mixing a part of the CO gas with air sucked into the converter mouth portion.
The inventors of the present application confirmed that, in the light emission spectrum, the internal condition of the converter can be easily estimated in real time by measuring the light emission intensity for each wavelength in real time for wavelengths ranging from 580 to 620 nm. Further, the present inventors have confirmed that, when FeO is generated, a light absorption peak is observed in the wavelength region, and when FeO is disappeared, a light emission peak is observed in the same wavelength region, wherein the light emission intensity is linked to the disappearing speed of FeO.
What is monitored is the emission or absorption of electromagnetic waves of a specific wavelength mainly upon the transition of the electronic state of FeO generated at the fire point of the molten iron bath in the melting furnace. Since FeO is integrated with the flame rising from the furnace, for example, the amount of FeO generated and the amount of FeO reacted decrease near the end of the decarburization reaction, and therefore, when the light emission spectrum of the flame is split, the emission intensity at a wavelength of 580 to 620nm decreases. That is, if the decarburization reaction rate is limited by the mass transfer rate of carbon in the molten metal, feO is produced predominantly compared with the reduction of FeO, and the emission intensity at a wavelength of 580 to 620nm is rapidly decreased.
Next, a method of measuring the temperature of the molten iron 6 when the molten iron 6 used in the blowing by the spectroscopic camera 7 flows from the molten iron holding vessel 30 into the converter 2 will be described.
Fig. 3 is a schematic view showing measurement of the temperature of molten iron flowing from the molten iron holding vessel into the converter. When the molten iron 6 used as the raw material for the converting flows into the converter 2 from the molten iron holding vessel 30, the spectroscopic camera 7 is provided, for example, in front of the charging side of the converter in the case of measuring the temperature of the molten iron, and the site of the injection flow when the molten iron 6 flows into the converter 2 from the molten iron holding vessel 30 can be observed. If the spectroscopic camera 7 is provided at an angle of looking up the injection flow, it is not easily affected by dust generated when molten iron is charged, and therefore, it is preferable. In the spectroscopic camera 7, 2-color temperature information is collected at a predetermined sampling rate (for example, every 1 second) from the start to the end of molten iron charging.
The 2-color temperature information acquired by the spectroscopic camera 7 is sent to the image analysis device 8, and the molten iron temperature is calculated by the image analysis device 8. The calculated molten iron temperature is input to the 1 st computer 9, and the 1 st computer 9 performs successive calculations of the "during-blowing temperature estimated value" using a value determined based on the input molten iron temperature as an initial value of the "during-blowing temperature estimated value".
By using a value determined based on the molten iron temperature measured by the spectroscopic camera 7 as an initial value of the "during-blowing temperature estimation value", the accuracy of temperature estimation at the time of mid-gun input is further improved.
As a method for measuring 2-color temperature information by the spectroscopic camera 7, a plurality of wavelength data may be collected by the spectroscopic camera 7, and any 2-wavelength data may be extracted from the obtained data by the image analysis device 8 or the like, and if the spectroscopic camera has a band-pass filter therein, any 2-wavelength data may be extracted by the band-pass filter. In addition, the spectroscopic camera 7 usually takes an image with a CCD element, but a plurality of CCD elements may be mounted, and each CCD element may measure a different wavelength range.
The spectroscopic camera 7 may be provided separately for measuring the optical characteristics of the converter mouth during converting (the rate of change in the luminous intensity of the spectrum caused by the reduction reaction of iron oxide in the slag) and the temperature of molten iron charged into the converter, or may be used in common. In the case of sharing, the device is provided in a place where both the furnace mouth combustion flame 18, which is seen from the gap between the furnace mouth 20 and the movable cover 21 of the converter 2, and the injection flow of the molten iron 6 when flowing into the converter 2 from the molten iron holding container 30 can be observed. Alternatively, the moving mechanism may be provided so that the molten iron charging is performed at a position where the injection flow of the molten iron 6 from the molten iron holding vessel 30 into the converter 2 can be observed, and the molten iron charging is performed at a position where the burner flame 18, which is seen from the gap between the mouth 20 of the converter 2 and the movable cover 21, can be observed before the start of the blowing.
As described above, according to the present invention, in the converter operation method in which the molten steel temperature and the molten steel composition at the time of stopping blowing are controlled to the target values by using the static control and the dynamic control, the molten metal temperature at the time of mid-gun charging is controlled to be within the range in which the molten steel temperature and the molten steel composition at the time of stopping blowing can be brought to the target values by the correction under the dynamic control, and therefore, the molten steel temperature and the molten steel composition at the time of stopping blowing can be brought to the target values with high accuracy.
Examples
After desulfurization and dephosphorization of molten iron, 300 to 350 tons of molten iron was subjected to oxygen blowing by static control, intermediate sublance charging, and dynamic control using a top-bottom blowing converter (top-bottom blowing oxygen gas, bottom blowing argon gas) having a capacity of 350 tons as shown in fig. 2, and decarburization refining was performed on the molten iron to produce molten steel. The target molten steel temperature at the time of stopping blowing is varied depending on the blowing, and is in the range of 1660 to 1700 ℃. The target molten steel temperature at the time of stopping the blowing in each blowing was reached within a range of + -10 deg.C of the target molten steel temperature. The chemical composition of the molten iron used in the blowing and the temperature of the molten iron are shown in table 1.
TABLE 1
The amount of combustion of the components in the furnace is determined so that the error in the balance of oxygen in the furnace is minimized, based on the relationship between the amount of oxygen supplied from the top-blown lance and the amount of solid oxygen (iron ore or the like) in the exhaust gas flow meter and the exhaust gas analyzer provided in the flue of the exhaust gas treatment facility of the converter. The obtained reaction amount of the furnace components is converted into reaction heat, and the "estimated value of the temperature during blowing" is calculated successively. Further, the "estimated value of carbon concentration during blowing" was estimated successively by calculating the mass balance of oxygen and carbon.
At the time of charging molten iron into the converter, molten iron that is seen between the converter mouth and the molten iron holding vessel is photographed by a spectroscopic camera. The temperature of molten iron at the time of charging into the converter was calculated from the luminescence intensities of 550nm and 850nm in the luminescence spectrum of the obtained molten iron. In converting, a spectroscopic camera is used to capture the emission spectrum of the burner flame, and the emission intensity of each wavelength is measured in real time for wavelengths ranging from 580 to 620nm in the emission spectrum. The wavelength used was 610nm. The spectroscopic camera was provided at a location where the furnace mouth combustion flame and the injection flow of molten iron from the molten iron holding vessel into the converter were observed using a moving mechanism using 1 spectroscopic camera.
In the present embodiment, the temperature of molten iron measured at the time of charging molten iron into the converter is used as an initial value of the "estimated temperature during blowing", and the "estimated temperature during blowing" is successively calculated. Further, when the "estimated value of carbon concentration during blowing" is estimated by using the calculation of the mass balance of oxygen and carbon, the "estimated value of carbon concentration during blowing" is estimated successively by using the analysis image data of the emission spectrum of the burner combustion flame.
In the present example, the time at which the "estimated value of the carbon concentration during blowing" reached 1.2 mass% was determined as the "confirmation time", and the "intermediate temperature target value" was obtained by the above formula (1) based on the target molten steel temperature at the time of stopping the blowing. The "intermediate temperature target value" is in the range from "target molten steel temperature at the time of stopping blowing-35 ℃ to" target molten steel temperature at the time of stopping blowing-65 ℃.
In the present example, the "intermediate temperature difference" was obtained by using the formula (3) at the time when the "estimated value of the carbon concentration during blowing" reached 1.2 mass%. When the determined "intermediate temperature difference" exceeds +15℃, iron ore as a cooling material is charged into the furnace before the intermediate sublance is charged. On the other hand, when the "intermediate temperature difference" is lower than-15 ℃, a carbon material (carbon content 75 mass% or more) as a heating material is charged into the furnace before the intermediate sublance is charged.
The amounts of iron ore as a cooling material and carbon material as a temperature raising material to be charged are obtained by multiplying the "intermediate temperature difference" by the cooling coefficient and the temperature raising coefficient, respectively. The cooling coefficient and the heating coefficient were obtained from the past blowing calculation results by weight regression, and the cooling coefficient was-0.18 [ (iron ore. Kg)/(molten iron. Ton. Times.) ], and the heating coefficient was +0.25[ (carbon material. Kg)/(molten iron. Ton. Times.) ].
Then, based on the "estimated value of carbon concentration during blowing", which is a successive estimated value of carbon concentration in the molten metal, a timing at which the decarburization efficiency starts to decrease (carbon concentration in the molten metal: 0.45 mass%) was determined, and a sublance was put in the middle of the timing.
After the intermediate sublance is thrown in, dynamic control is performed based on the measured values of the molten metal temperature and the carbon concentration in the molten metal of the intermediate sublance, and an operation shown by the dynamic control is performed to terminate oxygen blowing.
On the other hand, in the comparative example, the molten iron temperature measured at the time of charging the molten iron into the converter was not used as the initial value of the "temperature estimate during blowing", but the molten iron temperature measured by immersing the thermocouple in the molten iron filled in the molten iron holding container before charging into the converter was used as the initial value of the "temperature estimate during blowing", and the "temperature estimate during blowing" was successively calculated. Further, the "estimated value of carbon concentration during blowing" is estimated by calculating the mass balance of oxygen and carbon without using the analytical image data of the emission spectrum of the burner flame.
Then, the sublance was charged at the time when the "estimated value of carbon concentration during blowing" reached 0.45 mass%. Based on the measured values of the molten metal temperature and the carbon concentration in the molten metal measured by the intermediate sublance, dynamic control is performed, and the operation indicated by the dynamic control is performed, thereby ending the oxygen blowing.
Table 2 shows the test conditions and test results of the inventive examples and comparative examples.
TABLE 2
*1: a ratio in which the measured value of the molten metal temperature by the intermediate sublance satisfies a "intermediate temperature target value" + -15 ℃ at the intermediate sublance charging period and the measured value of the carbon concentration is 0.1 to 0.3 mass%
*2: the ratio of the carbon concentration in the molten steel at the time of stopping blowing to the carbon concentration of + -0.015 mass% at the time of stopping blowing at + -10deg.C, which is a target temperature
It was confirmed that the standard reaching rate at the time of stopping the blowing (end point) in the present example was as high as 87%, and the standard reaching rate at the time of stopping the blowing (end point) was significantly improved as compared with the comparative example.
Fig. 4 is a graph showing a relationship between a molten metal temperature and a carbon concentration in the molten metal at a time of a sub-gun charging in the middle of the present invention example and the comparative example. As is clear from fig. 4, in the example of the present invention, it was confirmed that the deviation of the molten metal temperature at the time of the midway sub-gun charging from the target molten steel temperature at the time of stopping blowing was reduced, and the molten metal temperature at the time of the midway sub-gun charging was controlled.
Fig. 5 is a graph showing an error between a target molten steel temperature at the time of stopping blowing and an actual molten steel temperature at the time of stopping blowing in examples of the present invention and comparative examples. As shown in fig. 5, it was confirmed that the molten steel temperature at the time of stopping blowing can be controlled to the target molten steel temperature with high accuracy according to the present invention.
Description of the reference numerals
1 converter plant
2 converter
3 top-blowing spray gun
4-bottom blowing port
5 sublance
6 molten iron
7 beam-splitting camera
8 image analysis device
9 st computer 1
10 nd computer 2
11 rd computer 3
12 computer for controlling operation
13 spray gun height control device
Lifting control device for 14 sublance
15 oxidizing gas flow control device
16 bottom blowing gas flow control device
17 auxiliary raw material input control device
18 burner combustion flame
19 jet of oxidizing gas
20 furnace mouth
21 movable cover
22 exhaust flowmeter
23 gas analyzer
24 furnace charging hopper
25-pair raw material input chute
Oxidizing gas supply pipe of 26 top-blowing spray gun
Cooling water supply pipe of 27 top-blowing spray gun
Cooling water discharge pipe of 28 top-blowing spray gun
29 flue
30 molten iron holding vessel
Claims (12)
1. In a method for operating a converter in which a sublance is charged into the converter during blowing of molten iron into the converter by blowing an oxidizing gas to decarburize the molten iron, a sublance measurement value including at least the molten metal temperature of the molten metal in the converter is measured, and the amount of oxygen to be supplied until the blowing is stopped and whether or not a cooling material or a heating material and the charge amount are charged are determined based on the measured sublance measurement value, whereby the temperature and the component concentration of the molten steel at the time of stopping the blowing are controlled to target values,
A target value of the molten metal temperature at the time of the sub-gun charging, that is, a target value of the intermediate temperature, is determined, and a timing for confirming a difference between the target value of the intermediate temperature and a predicted value of the intermediate temperature, which is a predicted value of the molten metal temperature at the time of the sub-gun charging, in converting before the time of the sub-gun charging is determined,
based on the operating conditions and measured values of the converter obtained at the start of the blowing and during the blowing, an estimated value of the temperature of the molten metal at the time of the progress of the blowing, that is, an estimated value of the temperature during the blowing and an estimated value of the carbon concentration in the molten metal, that is, an estimated value of the carbon concentration during the blowing,
and when the blowing is performed to the confirmation timing, calculating the intermediate temperature difference based on the in-blowing temperature estimation value and the in-blowing carbon concentration estimation value,
when the absolute value of the calculated intermediate temperature difference is greater than a preset threshold value, the cooling material or the heating material is charged into the converter during blowing after the confirmation timing and before charging into the sublance.
2. The method according to claim 1, wherein the confirmation timing is determined based on an estimated value of the carbon concentration in the converting.
3. The method for operating a converter according to claim 2, wherein the confirmation timing is determined within a range of 0.6 to 1.4 mass% of the estimated value of the carbon concentration in the blowing.
4. A method of operating a converter according to any one of claims 1 to 3, wherein the predetermined threshold value is a value selected from values above 10 ℃.
5. The method according to any one of claims 1 to 4, wherein, when the absolute value of the intermediate temperature difference is greater than a preset threshold value, the amount of cooling material or the amount of heating material to be charged during the blowing after the confirmation timing and before charging into the sublance is determined based on 1 or 2 or more of the estimated value of the temperature during the blowing, the target value of the molten steel temperature at the time of stopping the blowing, and the amount of quicklime to be charged into the converter during the blowing.
6. The method according to any one of claims 1 to 5, wherein the measurement values of the converter obtained at the start of blowing and during blowing include any one or both of measurement values obtained by an exhaust gas flow meter and an exhaust gas analyzer.
7. The operating method of a converter according to any one of claims 1 to 6, wherein the measured value of the converter obtained at the start of blowing and in blowing is a measured value related to an optical characteristic of a converter mouth in blowing, including a rate of change in luminous intensity of a spectrum caused by a reduction reaction of iron oxide in slag.
8. The operating method of a converter according to any one of claims 1 to 7, wherein the measured values of the converter obtained at the start of blowing and during blowing include a molten iron temperature measured using a non-contact optical method when molten iron used as a raw material for the blowing flows into the converter from a molten iron holding container.
9. A blowing control system for a converter, comprising:
a sublance for measuring a measured value of a sublance including at least a molten metal temperature of a molten metal in a converter in blowing in which an oxidizing gas is blown into molten iron in the converter to decarburize and refine the molten iron;
a 1 st computer that sequentially estimates an estimated value of a temperature during blowing, which is an estimated value of a temperature of molten metal at a time of blowing and an estimated value of a carbon concentration in molten metal, which is an estimated value of a carbon concentration during blowing, based on operating conditions and measured values of a converter obtained at a start of blowing and during blowing, and calculates an amount of oxygen to be supplied for bringing a temperature and a component concentration of molten steel at a time of stopping blowing to target values, and whether or not a cooling material, a heating material, and an amount of charge are to be charged based on a sublance measured value measured by the sublance;
an operation control computer that controls an operation condition so that a molten steel temperature and a carbon concentration in molten steel at the time of stopping blowing become target values, based on the oxygen amount and the amount of the cooling material or the heating material calculated by the 1 st computer;
A 2 nd computer that sets a target value of the molten metal temperature at the time of the sub-gun charging, that is, a target value of the intermediate temperature, and sets a timing for confirming a difference between the target value of the intermediate temperature and a predicted value of the intermediate temperature, that is, a predicted value of the molten metal temperature at the time of the sub-gun charging, in converting before the time of the sub-gun charging,
the 2 nd computer calculates a midway temperature difference, which is a difference between the midway temperature target value and the midway temperature predicted value, and determines whether or not to perform the cooling material or the heating material in the converter during the blowing after the confirmation timing and before the sublance is put in, based on the calculated absolute value of the midway temperature difference; and
and a 3 rd computer for calculating the amount of the cooling material or the amount of the heating material to be charged when the cooling material or the heating material is charged.
10. The converting control system of a converter according to claim 9, wherein an exhaust gas treatment facility of the converter includes an exhaust gas flowmeter and an exhaust gas analyzer, and data of the exhaust gas measured by the exhaust gas flowmeter and the exhaust gas analyzer is transmitted from the exhaust gas flowmeter and the exhaust gas analyzer to the 1 st computer, and the 1 st computer is configured to use the transmitted data of the exhaust gas for successive estimation of an in-converting temperature estimation value and an in-converting carbon concentration estimation value.
11. The converting control system of a converter according to claim 9 or 10, comprising: a spectroscopic camera arranged around the converter and shooting a burner flame from a gap between the converter and the movable cover; an image analysis device for removably recording image data transmitted from the spectroscopic camera and calculating the emission intensity of the image data at a wavelength ranging from 580 to 620nm,
the data of the emission intensity is transmitted from the image analysis device to the 1 st computer, and the 1 st computer is configured to use the transmitted data of the emission intensity for successive estimation of the temperature estimation value during blowing and the carbon concentration estimation value during blowing.
12. The converter blowing control system according to any one of claims 9 to 11, comprising a temperature measuring device for optically measuring a temperature of molten iron used as a raw material for converter blowing during a period in which the molten iron is charged into the converter as a molten iron temperature at the time of charging, wherein data of a temperature measurement value of the temperature measuring device is transmitted from the temperature measuring device to the 1 st computer, and wherein the 1 st computer is configured to use the transmitted data of the temperature measurement value in a successive estimation of an in-process temperature estimation value and an in-process carbon concentration estimation value.
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| JP2020-205676 | 2020-12-11 | ||
| JP2020205676 | 2020-12-11 | ||
| PCT/JP2021/042572 WO2022124050A1 (en) | 2020-12-11 | 2021-11-19 | Converter operation method and converter blowing control system |
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| CN116547392A true CN116547392A (en) | 2023-08-04 |
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| JP (1) | JP7088439B1 (en) |
| KR (1) | KR20230098852A (en) |
| CN (1) | CN116547392A (en) |
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| CN115522011A (en) * | 2022-09-02 | 2022-12-27 | 包头钢铁（集团）有限责任公司 | Method for improving smelting heat balance of converter by adjusting adding time of temperature raising agent coke of converter |
| CN115232907B (en) * | 2022-09-23 | 2022-12-20 | 北京科技大学 | Method and system for predicting oxygen blowing amount in converter steelmaking |
| CN116067900B (en) * | 2023-03-29 | 2023-06-16 | 北京科技大学 | Method and device for analyzing temperature and composition data of autonomous luminous monitoring molten pool in fire spot area |
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| JP4677955B2 (en) * | 2006-06-08 | 2011-04-27 | 住友金属工業株式会社 | Converter blowing control method, converter blowing control device, and computer program |
| JP5527180B2 (en) * | 2010-11-29 | 2014-06-18 | 新日鐵住金株式会社 | Converter blowing method and converter blowing system |
| JP5924186B2 (en) * | 2011-08-23 | 2016-05-25 | Ｊｆｅスチール株式会社 | Method of decarburizing and refining hot metal in converter |
| CN110809629B (en) * | 2017-06-30 | 2022-04-05 | 杰富意钢铁株式会社 | Method for monitoring operation of converter and method for operating converter |
| JP7043949B2 (en) * | 2018-04-10 | 2022-03-30 | 日本製鉄株式会社 | T. Fe estimation method, T.I. Fe control method, converter blow control device, and program |
| US11966669B2 (en) | 2018-05-14 | 2024-04-23 | Jfe Steel Corporation | Molten metal component estimation device, method of estimating molten metal component, and method of manufacturing molten metal |
| JP6954262B2 (en) | 2018-12-28 | 2021-10-27 | Ｊｆｅスチール株式会社 | How to operate the converter |
| CN113512620B (en) * | 2020-04-10 | 2024-04-26 | 北京凯德恒源科技发展有限公司 | Dynamic control method for endpoint carbon in whole converter smelting process of gas analysis and sublance |
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| JPWO2022124050A1 (en) | 2022-06-16 |
| TWI804075B (en) | 2023-06-01 |
| TW202225418A (en) | 2022-07-01 |
| KR20230098852A (en) | 2023-07-04 |
| WO2022124050A1 (en) | 2022-06-16 |
| JP7088439B1 (en) | 2022-06-21 |
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