A method for evaluating and adjusting the permeability state of a blast furnace hearth column

Abstract

The application discloses a method for evaluating and adjusting the liquid permeability state of a blast furnace hearth column, comprising the following steps: step 1, counting and calculating the daily output, tapping data and hearth thermocouple data of the blast furnace in a recent period T; step 2, calculating the average daily output in each of the t days before and after each day in the recent period T, and marking the day if the average daily output exceeds the daily output designed for the blast furnace; step 3, calculating the liquid permeability state index Q of the hearth column of each day; step 4, evaluating and adjusting the liquid permeability of the hearth column according to the index Q, and giving adjustment suggestions when the average value of the index Q in continuous t days is less than 0.8 or the average value of the index Q in continuous 10 days is less than 0.9, which indicates that the liquid permeability of the hearth column is poor. The application is beneficial to timely adjusting the state of the blast furnace hearth, improving the output of the blast furnace, reducing the abnormal fluctuation of the blast furnace and saving production cost.

Description

Technical Field

[0001] This invention relates to the field of blast furnace metallurgy technology, specifically to a method for evaluating and adjusting the liquid permeability of the blast furnace hearth charge column. Background Technology

[0002] Although blast furnace ironmaking has achieved a high level of mechanization and automation, the internal state of a blast furnace is difficult to monitor directly because it is a large, closed, continuous reactor with high internal temperatures and complex physicochemical reactions. As a result, judging the internal state of a blast furnace has always been a key focus and challenge in ironmaking research.

[0003] The blast furnace hearth, located at the bottom of the furnace, is the area where molten iron and slag converge and flow out. The hearth contains a large amount of solid coke as a charge column, and the permeability of this charge column determines the flowability of the molten iron, which is crucial for both blast furnace output and hearth lifespan. Prolonged poor permeability of the charge column in the hearth can lead to hearth buildup, resulting in significant production and economic losses. Furthermore, the assessment of the charge column's permeability in the hearth is typically based on current furnace bottom thermocouple readings or tapping conditions, relying on operator experience. This method is not accurate enough, and the assessment and adjustment of the hearth condition are often delayed.

[0004] In recent years, many large steel plants have conducted research on the state inside the blast furnace hearth. Steel plants such as Taiyuan Iron & Steel, Benxi Steel, and Shougang Jingtang have proposed indices and calculation methods that can reflect the permeability of the material column inside the hearth based on their own blast furnace production practices.

[0005] As early as 2002, Baoshan Iron and Steel Plant proposed the concept of a blast furnace hearth activity index. Its basic principle is to divide the weighted value of the furnace bottom thermocouple temperature by the weighted value of the hearth sidewall thermocouple temperature. Steel plants such as Taiyuan Iron & Steel and Benxi Iron & Steel use similar methods, but the algorithms have been modified and differ. Shougang proposed the concept of a hearth tapping index, using the amount of iron tapped each time to measure changes in the hearth tapping situation, thereby judging changes in the hearth's internal state. Tangshan Iron & Steel proposed a physical-thermal index, using the correspondence between the physical and chemical heat of molten iron to measure whether the physical heat of molten iron is within a reasonable range, monitoring changes in the hearth's state. These methods are relatively simple and easy to apply in practice. However, the hearth thermocouple temperature is greatly affected by the hearth erosion state, and the tapping state is greatly affected by factors such as furnace heat state and slag basicity. Therefore, evaluating the permeability of the charge column inside the hearth solely based on thermocouple status or the current tapping state can easily lead to significant errors.

[0006] Professor Wu Shengli and others from the University of Science and Technology Beijing proposed the Hearth Activity Index, which uses the total resistance coefficient of slag and iron flow, consisting of the resistance coefficients of slag and iron flowing into and out of the hearth, to characterize the activity of the hearth. In principle, this index can accurately reflect the permeability of the material column in the hearth, but in actual production, it is difficult to obtain relevant data such as the resistance coefficient.

[0007] In addition, patent application CN201910694721.X, entitled "A Quantitative Characterization Method for Blast Furnace Hearth Activity," provides a method for quantitatively characterizing blast furnace hearth activity. Based on the slag-iron flow resistance coefficient, it defines the resistance encountered by slag and iron during the flow into and out of the hearth as the resistance coefficient of slag-iron into the hearth and the resistance coefficient of slag-iron into the hearth, respectively. It then analyzes and integrates the hearth activity states corresponding to these three cases to construct a new hearth activity index, thus achieving a quantitative characterization of hearth activity. However, in actual production, it is difficult to obtain the required data. Patent application number 201410641712.1, entitled "A Method for Quantitative Evaluation of Blast Furnace Hearth Activity," discloses a method for quantitatively evaluating blast furnace activity. The method includes selecting blast furnace operating parameters; constructing a quantitative evaluation formula for hearth activity using the weighted sum of the fluctuation values ​​of the blast furnace operating parameters; determining the base values ​​of the blast furnace operating parameters for the quantitative evaluation formula based on the specific blast furnace; inputting the actual values ​​of the blast furnace operating parameters under normal production conditions; inputting the base values ​​and actual values ​​of the blast furnace operating parameters into the quantitative evaluation formula for hearth activity; calculating the hearth activity evaluation index; and comparing intervals to classify the degree of hearth activity to guide blast furnace production. While using blast furnace operating parameters to judge the degree of hearth activity is reasonable, as these parameters are generally more affected by other factors, the results may have significant errors. Patent application CN201810596710.3, entitled "A System, Method, and Apparatus for Detecting the Activity of a Blast Furnace Hearth," provides a system, method, and apparatus for detecting the activity of a blast furnace hearth. Through experimental testing, the calculated slag-iron retention rate can accurately reflect the activity of the blast furnace hearth in real time. However, judging through experimental methods, the difference between the experimental results and the actual internal state of the blast furnace is difficult to determine.

[0008] Although many steel industry professionals in China have conducted extensive research on the permeability of the charge column in the blast furnace hearth and proposed various quantitative indices such as the hearth activity index, a universally accepted calculation method that can reflect the permeability of the charge column in the hearth has not yet been established. Therefore, it is necessary to provide an accurate, simple, and practical method to evaluate and adjust the permeability of the charge column in the blast furnace hearth, based on previous research, to assist in the control of the blast furnace hearth. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for evaluating and adjusting the liquid permeability of the blast furnace hearth charge column, which is beneficial for timely adjustment of the blast furnace hearth state, increasing blast furnace output, reducing abnormal fluctuations in blast furnace output, and saving production costs, in order to address the above-mentioned deficiencies in the existing technology.

[0010] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0011] A method for evaluating and adjusting the liquid permeability of the blast furnace hearth burden column includes the following steps:

[0012] Step 1: Collect and calculate the daily output, tapping data, and hearth thermocouple data of the blast furnace within the recent period T.

[0013] Step 2: Calculate the daily data for the most recent period T, and calculate the average daily output for each day t days before and after each day. If the output exceeds the designed daily output of the blast furnace, mark that day.

[0014] Step 3: Calculate the daily permeability index Q of the furnace hearth charge column;

[0015] Step 4: Evaluate and adjust the permeability of the furnace hearth column based on the index Q. If the average value of the index Q is less than 0.8 for t consecutive days or less than 0.9 for 10 consecutive days, it is judged that the permeability of the furnace hearth column has deteriorated; then adjustment suggestions are given.

[0016] According to the above technical solution, in step 1, the tapping data mainly includes the tap number, molten iron temperature, and silicon content of each tap, while the furnace hearth thermocouple data mainly includes the furnace core temperature.

[0017] According to the above technical solution, the furnace core temperature is the temperature of the thermocouple closest to the radial center point at the top of the furnace bottom. If the thermocouple is damaged due to furnace bottom erosion and the data is missing or abnormal, the temperature of the thermocouple directly below the thermocouple is taken as the furnace core temperature.

[0018] According to the above technical solution, in steps 1 and 2, the time T is one year.

[0019] According to the above technical solution, in steps 2 and 4, t is 4 or 5, or 6.

[0020] According to the above technical solution, in step 3, the permeability index Q of the furnace hearth charge column is...

[0021]

[0022] In the formula, T 芯 The average furnace core temperature for the day. T represents the average core temperature over all these marked days. 铁 It is the average of the absolute values ​​of the temperature difference between each tapping and the previous tapping within the same day. W is the average of the absolute values ​​of the temperature difference between the molten iron tapped each time and the previous tapped time for all the marked days. 硅 It is the average of the absolute values ​​of the difference in water and silica content between each iron tapping session on the same day and the previous iron tapping session. This is the average of the absolute values ​​of the difference in water and silica content between each iron tapping and the previous iron tapping within all marked days.

[0023] Based on the above technical solution, calculate the average furnace core temperature T for that day. 芯 Calculate the average value T of the absolute value of the temperature difference between each tapping and the previous tapping within the same day, following the method in step one. 铁 The average value of the absolute value of the difference between water and silicon content W 硅 .

[0024] Calculate the average core temperature for all marked days. Blast furnaces typically tap iron continuously from opposite sides. Each tapping operation involves a judgment: if the tapping point from the previous tapping is opposite the tapping point of the current tapping, and the time interval between the two tappings does not exceed 4 hours, then the difference in iron temperature and silicon content between the current and previous tappings is calculated. The average of the absolute values ​​of the temperature differences between each tapping and the previous tapping within these marked days is then calculated. The average of the absolute values ​​of the difference between water and silicon content

[0025] According to the above technical solution, in step 4, there are multiple ways to adjust the measures based on the actual situation of the blast furnace, including improving the quality of blast furnace coke, reducing coke load, increasing blast temperature, reducing the air inlet area of ​​the tuyeres, increasing the length of the tuyeres, and reducing the basicity of the slag; select the appropriate adjustment measures and suggestions according to the specific situation.

[0026] According to the above technical solution, it is recommended to adjust the measures until the average permeability index of the furnace hearth column is not less than 1 for 15 consecutive days.

[0027] The present invention has the following beneficial effects:

[0028] Specifically, this invention evaluates the permeability of the blast furnace hearth charge column based on historical and current data of blast furnace hearth thermocouple temperature, molten iron temperature, and molten iron silicon content. When the permeability of the hearth charge column is poor, it proposes adjustments to blast furnace operation to ensure that the permeability of the blast furnace hearth charge column is in a better state. Compared with the traditional method that only judges based on the current furnace bottom thermocouple temperature or iron tapping status, the method provided by this invention considers both historical and current data of thermocouple temperature and iron tapping status, making it more timely and accurate. This facilitates timely adjustments to the blast furnace hearth status, increases blast furnace output, reduces abnormal fluctuations in blast furnace performance, and saves production costs. Attached Figure Description

[0029] Figure 1 This is a 3000m example from an embodiment of the present invention. 3 The change in the permeability index of the hearth charge column over a period of time is calculated using the method of this invention for a blast furnace. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Reference Figure 1 As shown, one embodiment of the present invention provides a method for evaluating and adjusting the liquid permeability of the blast furnace hearth burden column. Applying this method to a 3200m³ blast furnace hearth is illustrated. 3 Blast furnace, the steps are as follows:

[0032] Step 1: Collect and calculate the daily output, tapping data, and core temperature data of the blast furnace for approximately the most recent year (for example, when calculating on June 1, 2021, data from May 22, 2020 to May 31, 2021 were collected as needed). The tapping data mainly includes the tap number, molten iron temperature, and silicon content of each tap. Since the thermocouple closest to the radial center point at the top of the furnace bottom is damaged and unavailable, the temperature of the nearest thermocouple directly below that thermocouple is collected as the core temperature.

[0033] Step 2: Calculate the daily data for the year (e.g., when calculating on June 1, 2021, calculate the daily data from May 27, 2020 to May 26, 2021 according to the data requirements of the calculation method). Calculate the average daily output for each day preceding and following 5 days. The blast furnace is designed to have a daily output of 8000t. If the calculated average daily output exceeds the blast furnace's designed daily output, mark that day (e.g., when calculating on June 1, 2021, a total of 247 days were marked). Calculate the average core temperature for all marked days. (For example, when calculating on June 1, 2021,) In blast furnaces, iron is typically tapped continuously from opposite sides. Each tapping is evaluated; if the tapping point from the previous tapping is opposite the tapping point from the current tapping point, and the time between the two tappings does not exceed 4 hours, then the difference in iron temperature and silicon content between the current and previous tappings is calculated. The average of the absolute values ​​of the temperature differences between each tapping and the previous tapping within these marked days is then calculated. (For example, when calculating on June 1, 2021,) The average of the absolute values ​​of the difference between the water and silicon content (For example, when calculating on June 1, 2021,) ).

[0034] Step 3: Calculate the average furnace core temperature T for the day. 芯 (For example, June 1, 2021 T) 芯 =396.6℃), calculate the average value T of the absolute value of the temperature difference between each tapping and the previous tapping within the same day, following the method in step one. 铁 (For example, June 1, 2021 T) 铁 =9.36℃) and the average value of the absolute value of the difference between the water and silicon content W 硅 (For example, June 1, 2021) The permeability index Q of the furnace hearth column on that day was calculated according to formula (1) in the above invention (e.g., Q = 1.02 on June 1, 2021). The result was obtained by calculating using this method. Figure 1 Chinese data.

[0035] Step 4: Evaluate and adjust the permeability of the hearth burden column based on the index Q. In early June 2021, due to abnormal fluctuations such as the large-scale shedding of blast furnace slag, the permeability of the hearth burden column gradually deteriorated. Figure 1 As shown, by June 12th, the average value of the index Q had been less than 0.9 for 10 consecutive days (the average value dropped to 0.898 from June 2nd to June 11th). The blast furnace began implementing control measures, strengthening coke testing and screening management to ensure coke quality. The coke load decreased from approximately 4.65 to approximately 4.55, while the blast temperature remained above 1180℃, and the tuyeres area decreased from 0.409 m². 2 Reduced to 0.395m 2 Considering the requirements for molten iron desulfurization, the slag basicity was not adjusted. After adjustment, the permeability of the hearth charge gradually improved, and by July 2, the average permeability index of the hearth charge over 15 consecutive days reached 1.002, indicating that the permeability of the hearth charge had recovered.

[0036] Finally, it should be noted that the above specific embodiments are merely illustrative of the technical solutions of the present invention and not limiting thereof. Technical solutions formed by equivalent substitutions based on the technical solutions of the present invention all fall within the protection scope of the present invention.

[0037] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent changes made in accordance with the claims of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method of evaluating and adjusting the state of the permeability of a stock column in the hearth of a blast furnace, characterized in that, The method comprises the following steps: Step 1, statistics and calculation of blast furnace daily output, tapping data and hearth thermocouple data of blast furnace in the recent period T; Step 2, calculation of average daily output in each day data in the recent period T, if it exceeds the daily output of blast furnace design, mark the day; Step 3, calculation of hearth stock column liquid permeability state index Q of each day; Step 4, evaluation and adjustment of hearth stock column liquid permeability according to index Q, if the average value of index Q in continuous t days is less than 0.8 or the average value of index Q in continuous 10 days is less than 0.9, judge that the hearth stock column liquid permeability is poor; then give adjustment suggestion; In the step 1, the tapping data is the iron port number, the temperature of molten iron and the silicon content of molten iron, and the hearth thermocouple data is the core temperature; The core temperature is the temperature of the uppermost thermocouple closest to the radial center point of the hearth bottom, if the current thermocouple has been damaged due to hearth bottom erosion, there is no data or abnormal, then the temperature of the thermocouple closest to the bottom of the thermocouple is taken as the core temperature; In the step 4, the adjustment measures have multiple ways, including improving the quality of blast furnace coke, reducing coke load, improving air temperature, reducing air inlet area of tuyere, increasing tuyere length, reducing slag basicity; In the step 3, the hearth stock column liquid permeability state index Q （1） In the formula, is the average hearth temperature for the day, is the average hearth temperature for the time of all the marked days, is the average of the absolute value of the difference in the temperature of the molten iron for each tapping and the previous tapping within the day, is the average of the absolute value of the difference in the temperature of the molten iron for each tapping and the previous tapping for the time of all the marked days, is the average of the absolute value of the difference in the content of the water silicon for each tapping and the previous tapping within the day, is the average of the absolute value of the difference in the content of the water silicon for each tapping and the previous tapping for the time of all the marked days.

2. The method of evaluating and adjusting the permeability state of a blast furnace hearth column according to claim 1, characterized in that, In the step 1 and step 2, the time T is one year.

3. The method of evaluating and adjusting the permeability state of a blast furnace hearth column according to claim 1, characterized in that, In the step 2 and 4, t is 4 or 5, or 6.

4. The method of evaluating and adjusting the permeability state of a blast furnace hearth column according to claim 1, characterized in that, The adjustment measures are suggested to be implemented until the average hearth stock column liquid permeability index in continuous 15 days is not less than 1.

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