Method for judging physical heat matching of blast furnace molten iron

Abstract

The present application relates to the field of steel smelting. A method for judging the physical heat matching of blast furnace molten iron, P(KFTP)=(T-1150)×(1-FR / 800)×(1-[Si] / 4) / 50, wherein P(KFTP) is the physical heat matching index of molten iron; T is the average daily value of molten iron temperature measurement, unit ℃; FR is the fuel ratio per ton of iron, unit kg / t.Fe, if FR is greater than 800 kg / t.Fe, 800 kg / t.Fe is substituted for calculation; [Si] is the silicon content of molten iron, if [Si] is greater than 4%, 4% is substituted for calculation; when P(KFTP) is greater than or equal to 2.5: the matching is excellent, the heat balance in the furnace is stable, the physical heat of molten iron is sufficient and adapts to fuel consumption and silicon content, and there is no need to adjust the production process parameters; when 2.1≤P(KFTP) is less than 2.5: the matching is good, the furnace condition is basically stable, the current blast parameters can be maintained, and the blast parameters include blast temperature and oxygen content.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting. Background Technology

[0002] The physical-thermal matching of blast furnace hot metal, simply put, is whether the temperature of the hot metal is "in sync" with the smelting requirements. It directly affects the hearth heat, slag-iron fluidity, and subsequent steelmaking efficiency, and is a key indicator for optimizing blast furnace operation.

[0003] The core functions of physical heat matching include: Hearth heat balance: Physical heat must maintain the hearth to prevent underheating and ensure slag-iron fluidity. Smelting efficiency and cost: Insufficient physical heat leads to furnace condition fluctuations and increased fuel consumption; excessive heat may waste energy. Steelmaking process integration: High-temperature, low-silicon molten iron can shorten converter blowing time and reduce steelmaking energy consumption.

[0004] Currently, there are two main methods in the industry for judging the physical-thermal compatibility of molten iron: one is the direct observation method, which uses the appearance of molten iron and the characteristics of slag samples in combination with silicon and sulfur content for qualitative judgment; the other is the instrument monitoring and model prediction method, which relies on temperature measurement data or blasting conditions to estimate the temperature trend of molten iron.

[0005] However, existing technologies have obvious limitations: First, the evaluation dimensions are singular, relying only on single parameters such as temperature or silicon content, which cannot fully reflect the matching; second, the key parameter of fuel ratio per ton of iron is not included, while the fuel ratio is directly related to the heat balance in the furnace, causing the evaluation to deviate from the actual process; third, there is a lack of quantitative capabilities, with most of the descriptions being qualitative, making it difficult to accurately judge critical operating conditions, resulting in lagging control and high energy consumption.

[0006] The deficiencies in judging the physical-thermal matching of blast furnace hot metal have become a bottleneck for precise control of blast furnaces, and will also increase coke consumption and affect the quality of hot metal. Summary of the Invention

[0007] The technical problem to be solved by this invention is: how to accurately judge the physical-thermal matching of molten iron, so as to avoid abnormal furnace conditions and reduce energy consumption.

[0008] The technical solution adopted in this invention is a method for determining the physical-thermal compatibility of blast furnace molten iron. P(KFTP)=(T-1150)×(1-FR / 800)×(1-[Si] / 4) / 50 Wherein, P(KFTP) is the physical-thermal matching index of molten iron; T is the daily average temperature of molten iron, in °C; FR is the fuel ratio per ton of iron, in kg / t.Fe. If FR is greater than 800 kg / t.Fe, it is calculated based on 800 kg / t.Fe; [Si] is the mass percentage of silicon content in molten iron. If [Si] > 4%, it is calculated based on 4%. When P(KFTP)≥2.5: excellent matching, stable heat balance in the furnace, sufficient physical heat of molten iron and suitable for fuel consumption and silicon content, no need to adjust production process parameters; When 2.1≤P(KFTP)<2.5: the matching is good, the furnace condition is basically stable, and the current blast parameters can be maintained, including blast temperature and oxygen content; When 1.8≤P(KFTP)<2.1: the matching is critical, and there is a risk of heat imbalance, including low furnace temperature, high fuel consumption, or poor hearth activity. Heating measures need to be taken to increase the fuel ratio per ton of iron by 10-15 kg / t.Fe. When P(KFTP) < 1.8: poor matching, furnace condition is on the verge of abnormality, which may lead to a cold hearth, difficulty in slag-iron separation, poor hearth activity, and the need to take measures to increase the heat, increase the fuel ratio per ton of iron by 10-15 kg / t.Fe, and take measures to reduce the load and increase the coke ratio by 10-15 kg / t.Fe. The P(KFTP) value is calculated daily to form a continuous matching monitoring curve. When the P(KFTP) value is less than 1.8 for three consecutive days, it is judged that the physical and thermal matching of the blast furnace hot metal is extremely poor and does not meet the thermal regime requirements. Emergency control measures such as increasing heat, reducing load, and decreasing alkalinity need to be taken.

[0009] Data on daily blast furnace output, daily coke consumption, daily pulverized coal consumption, daily average silicon content (mass percentage) in molten iron, and daily average temperature of molten iron under blast furnace operating conditions were collected. Then, the calculation was performed according to FR = (daily blast furnace output + converted daily pulverized coal consumption) / daily blast furnace output, where the units for daily blast furnace output and converted daily pulverized coal consumption are kg, and the unit for daily blast furnace output is t. The converted daily pulverized coal consumption = daily pulverized coal consumption × conversion factor, with the conversion factor for daily pulverized coal consumption being 0.8-0.85. The mass percentage of silicon content in molten iron was taken as the daily average of silicon content in molten iron.

[0010] The beneficial effects of this invention are as follows: This invention overcomes the shortcomings of traditional methods by incorporating the "fuel ratio per ton of iron" into the evaluation system for the first time. It combines molten iron temperature measurement and silicon content to form a three-dimensional evaluation dimension, covering "heat output (temperature) - chemical thermal characterization (silicon content) - energy consumption and heat input (fuel ratio)," which better aligns with the complex heat balance logic within the furnace. Traditional formulas for calculating the physical-thermal matching of molten iron rely solely on two parameters: "molten iron temperature measurement" and "molten iron silicon content," neglecting the crucial indicator of the "fuel ratio per ton of iron." This fuel ratio directly relates to the heat output and heat balance of carbon combustion within the furnace; its fluctuations reflect the activity level of the hearth, directly affecting the compatibility between the physical-thermal matching of molten iron and furnace conditions. Consequently, traditional formulas fail to reflect the coupling relationship between energy consumption and physical-thermal matching, resulting in evaluation results that are detached from actual production. Furthermore, traditional methods lack outlier handling mechanisms (such as in scenarios with high silicon content and high fuel ratios) and can only calculate single values, lacking clear matching grading standards, making it difficult to guide specific furnace condition control and other issues.

[0011] This invention offers a more comprehensive and accurate evaluation: by integrating three-dimensional parameters—fuel ratio per ton of iron, silicon content in molten iron, and temperature measurement of molten iron—it overcomes the shortcomings of traditional methods, which rely solely on temperature and silicon content and lack standards for handling abnormal parameters and quantitative grading. Furthermore, it adds boundary handling rules for abnormal parameters, effectively avoiding evaluation distortions under scenarios of high fuel ratio, normal silicon content, and normal molten iron temperature measurement. This better aligns with the actual logic of the coupling of heat balance and energy consumption within the furnace, significantly improving the accuracy of judgments.

[0012] The control guidance of this invention is more operational: the calculation results are converted into four matching levels, each level corresponding to specific control measures, which solves the problem of the traditional method of "only producing numerical values ​​without guidance", and makes furnace condition control shift from "experience judgment" to "quantitative drive", which greatly shortens the abnormal response time and reduces the risk of abnormalities such as hearth cooling and difficulty in slag-iron separation.

[0013] This invention achieves cost reduction and efficiency improvement: accurate physical and thermal matching judgment can reduce ineffective fuel consumption, and combined with the periodic verification mechanism to continuously optimize the process, it can significantly reduce the fuel ratio per ton of iron and the furnace condition abnormality rate, while stabilizing the quality of molten iron, providing reliable support for the efficient and low-consumption operation of the blast furnace. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram illustrating the trend of the physical-thermal matching index of traditional molten iron. Detailed Implementation

[0015] In April and May of a certain year, the physical-thermal matching index of molten iron in a steel company was calculated using both the traditional method and the method of this invention.

[0016] The traditional method for evaluating the physical-thermal compatibility of blast furnace hot metal is as follows: P(KTP) =((T-1400) / 100) 2 / [Si] Wherein, P(KTP) is the physical-thermal matching index of molten iron; T is the daily average temperature value of molten iron in °C; and [Si] is the mass percentage of silicon content in molten iron.

[0017] The results are shown in Table 1 below.

[0018] The trend of traditional molten iron physical-thermal matching index is as follows: Figure 2 As shown, the physical-thermal matching of molten iron deteriorated on May 3, 2004, requiring adjustment. In reality, the blast furnace condition had already deteriorated in terms of physical-thermal matching of molten iron since April 11, 2024, exhibiting a significant increase in the fuel ratio. By May 3, the blast furnace coke ratio had increased from the normal 350 kg / t to 480 kg / t, and on May 8, it switched to full coke load, restoring furnace condition. The actual results demonstrate the distortion of traditional blast furnace physical-thermal matching evaluation under scenarios of high fuel ratio, normal silicon content, and normal molten iron temperature measurement.

[0019] like Figure 1 As shown, the physical-thermal matching index of molten iron is calculated according to the method of the present invention.

[0020] P(KFTP)=(T-1150)×(1-FR / 800)×(1-[Si] / 4) / 50 Wherein, P(KFTP) is the physical-thermal matching index of molten iron; T is the daily average temperature of molten iron, in °C; FR is the fuel ratio per ton of iron, in kg / t.Fe. If FR is greater than 800 kg / t.Fe, it is calculated based on 800 kg / t.Fe; [Si] is the mass percentage of silicon content in molten iron. If [Si] > 4%, it is calculated based on 4%. When P(KFTP)≥2.5: excellent matching, stable heat balance in the furnace, sufficient physical heat of molten iron and suitable for fuel consumption and silicon content, no need to adjust production process parameters; When 2.1≤P(KFTP)<2.5: the matching is good, the furnace condition is basically stable, and the current blast parameters can be maintained, including blast temperature and oxygen content; When 1.8≤P(KFTP)<2.1: the matching is critical, and there is a risk of heat imbalance, including low furnace temperature, high fuel consumption, or poor hearth activity. Heating measures need to be taken to increase the fuel ratio per ton of iron by 10-15 kg / t.Fe. When P(KFTP) < 1.8: poor matching, furnace condition is on the verge of abnormality, which may lead to a cold hearth, difficulty in slag-iron separation, poor hearth activity, and the need to take measures to increase the heat, increase the fuel ratio per ton of iron by 10-15 kg / t.Fe, and take measures to reduce the load and increase the coke ratio by 10-15 kg / t.Fe. The P(KFTP) value is calculated daily to form a continuous matching monitoring curve. When the P(KFTP) value is less than 1.8 for three consecutive days, it is judged that the physical and thermal matching of the blast furnace hot metal is extremely poor and does not meet the thermal regime requirements. Emergency control measures such as increasing heat, reducing load, and decreasing alkalinity need to be taken.

[0021] Data on daily blast furnace output, daily coke consumption, daily pulverized coal consumption, daily average silicon content (mass percentage) in molten iron, and daily average temperature of molten iron under blast furnace operating conditions were collected. Then, the calculation was performed according to FR = (daily blast furnace output + converted daily pulverized coal consumption) / daily blast furnace output, where the units for daily blast furnace output and converted daily pulverized coal consumption are kg, and the unit for daily blast furnace output is t. The converted daily pulverized coal consumption = daily pulverized coal consumption × conversion factor, with the conversion factor for daily pulverized coal consumption being 0.8-0.85. The mass percentage of silicon content in molten iron was taken as the daily average of silicon content in molten iron.

[0022] The results are shown in Table 2 below.

[0023] The deteriorating trend in the physical-thermal matching of molten hot metal as of April 1, 2004, necessitates timely adjustments. This aligns with the actual deterioration in the physical-thermal matching of molten hot metal under blast furnace conditions.

[0024] Traditional methods suffer from inaccuracies in evaluation under conditions of high fuel ratio, normal silicon content, and normal molten iron temperature measurement. This invention corrects the inaccuracies in traditional methods for evaluating the physical-thermal compatibility of molten iron in blast furnaces.

[0025] Under normal fuel ratios, the trends of this invention and traditional evaluation methods are consistent. Compared with traditional methods, the physical-thermal matching evaluation of blast furnace hot metal in this invention is more in line with the furnace operation trend, and is more accurate in evaluating blast furnace thermal regime adjustments and furnace conditions. It is also more representative than traditional evaluation methods.

Claims

1. A method for determining the physical-thermal compatibility of blast furnace hot metal, characterized in that: P(KFTP)=(T-1150)×(1-FR / 800)×(1-[Si] / 4) / 50 Wherein, P(KFTP) is the physical-thermal matching index of molten iron; T is the daily average temperature of molten iron, in °C; FR is the fuel ratio per ton of iron, in kg / t.Fe. If FR is greater than 800 kg / t.Fe, it is calculated based on 800 kg / t.Fe; [Si] is the mass percentage of silicon content in molten iron. If [Si] > 4%, it is calculated based on 4%. When P(KFTP)≥2.5: excellent matching, stable heat balance in the furnace, sufficient physical heat of molten iron and suitable for fuel consumption and silicon content, no need to adjust production process parameters; When 2.1≤P(KFTP)<2.5: the matching is good, the furnace condition is basically stable, and the current blast parameters can be maintained, including blast temperature and oxygen content; When 1.8≤P(KFTP)<2.1: the matching is critical, and there is a risk of heat imbalance, including low furnace temperature, high fuel consumption, or poor hearth activity. Heating measures need to be taken to increase the fuel ratio per ton of iron by 10-15 kg / t.Fe. When P(KFTP) < 1.8: poor matching, furnace condition is on the verge of abnormality, which may lead to a cold hearth, difficulty in slag-iron separation, poor hearth activity, and the need to take measures to increase the heat, increase the fuel ratio per ton of iron by 10-15 kg / t.Fe, and take measures to reduce the load and increase the coke ratio by 10-15 kg / t.Fe. The P(KFTP) value is calculated daily to form a continuous matching monitoring curve. When the P(KFTP) value is less than 1.8 for three consecutive days, it is judged that the physical and thermal matching of the blast furnace hot metal is extremely poor and does not meet the thermal regime requirements. Emergency control measures such as increasing heat, reducing load, and decreasing alkalinity need to be taken.

2. The method for determining the physical-thermal compatibility of blast furnace hot metal according to claim 1, characterized in that: Data on daily blast furnace output, daily coke consumption, daily pulverized coal consumption, daily average silicon content (mass percentage) in molten iron, and daily average temperature of molten iron under blast furnace operating conditions were collected. Then, the calculation was performed according to FR = (daily blast furnace output + converted daily pulverized coal consumption) / daily blast furnace output, where the units for daily blast furnace output and converted daily pulverized coal consumption are kg, and the unit for daily blast furnace output is t. The converted daily pulverized coal consumption = daily pulverized coal consumption × conversion factor, with the conversion factor for daily pulverized coal consumption being 0.8-0.

85. The mass percentage of silicon content in molten iron was taken as the daily average of silicon content in molten iron.

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