Method for measuring height of melt in blast furnace, device for measuring height of melt in blast furnace, and method for operating blast furnace

Abstract

A method for measuring the height of a melt in a blast furnace according to the present invention comprises: a measurement step for measuring a vibration frequency distribution in the height direction of a furnace body of the blast furnace using a plurality of vibrometers arranged at predetermined intervals in the height direction of the furnace body; a vibration intensity calculation step in which the vibration intensity of the frequency range originating from the blowing air at each measurement position is calculated by Fourier transform of the vibration frequency distribution; a numerical analysis step for calculating the maximum vibration intensity distribution of the lower part of the blast furnace using a numerical analysis model using the height of the melt in the blast furnace and the amount of blowing air as variables; and a melt height calculation step for calculating the melt height at which the difference between the vibration intensity calculated in the vibration intensity calculation step and the maximum vibration intensity distribution calculated in the numerical analysis step is minimum, and using the calculated melt height as the position of the melt height in the blast furnace.

Description

Technical Field

[0001] The present invention relates to a method for measuring the height of a melt in a blast furnace, a device for measuring the height of a melt in a blast furnace, and a method for operating a blast furnace. Background Art

[0002] In the ironmaking industry, the blast furnace is located at the most upstream process, so the stabilization technology of its operation is given attention. It is important to ensure good air permeability in the furnace for the stable operation of the blast furnace. As one of the factors hindering the air permeability in the furnace, the rise in the liquid level of molten iron and slag (hereinafter, the two are collectively referred to as the melt) retained in the filling layer at the bottom of the furnace can be cited. The rise in the liquid level of the melt (hereinafter, simply referred to as the melt height) causes the gas flow path in the furnace to be narrowed, which may become a direct cause of the increase in the air supply pressure. In addition, when the melt height reaches the air supply tuyere height, it may become the cause of major faults such as melt loss of the air supply tuyere, and then blockage of the air supply tuyere, and slag return (the phenomenon of the melt flowing back from the air supply tuyere). Therefore, in order to achieve stable operation of the blast furnace, the melt height should be reliably prevented from reaching the air supply tuyere height.

[0003] Against this backdrop, methods have been proposed to evaluate the amount of molten material remaining in the blast furnace based on the material balance according to various blast furnace operating specifications. Specifically, Patent Document 1 describes a method that uses the actual volume of material charged to the furnace and a theoretical volume calculated based on the operating specifications to determine the theoretical amount of molten material discharged from the blast furnace. The theoretical amount of molten material discharged is then compared to the actual amount of molten material discharged to estimate the amount of molten material remaining in the furnace. Furthermore, Patent Document 2 describes a method that estimates the molten material height in the furnace by assigning parameters representing the properties of the blast furnace's constituent materials, including the molten material height, to a general equation related to continuous ambient strain. The method then solves for variables measured by multiple strain gauges installed in the furnace body.

[0004] In addition, Patent Document 3 describes a method utilizing the so-called Bernoulli theorem, which calculates the discharge velocity of the molten material from the taphole of a blast furnace based on the discharge distance, discharge angle, and discharge height of the molten material, and uses this to infer the molten material height within the furnace. The accuracy of this method's inference depends on the accuracy of the calculation of the discharge velocity of the molten material from the taphole. In this method, the discharge velocity is estimated by image analysis of images captured by a camera. Furthermore, Patent Document 4 describes a method that measures the vibration intensity of the furnace wall at the bottom of the furnace and infers the molten material height within the furnace based on a previously determined relationship between the vibration intensity in a specific frequency band and the molten material height.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-302709

[0006] Patent Document 2: Japanese Patent Application No. 2015-528905

[0007] Patent Document 3: Japanese Patent No. 7056813

[0008] Patent Document 4: International Publication No. 2022 / 201717

[0009] However, the method described in Patent Document 1 does not consider the porosity of the filling layer below the furnace or the shape of the solidified layer. Therefore, even if the amount of melt remaining in the furnace can be estimated, estimating the melt level, which is crucial for stable blast furnace operation, remains a challenge. Furthermore, due to the influence of various weighing errors, estimation errors accumulate in large-volume blast furnace processes, raising the concern that estimation accuracy may decrease over time.

[0010] In addition, the method described in Patent Document 2 has the following problems. It is known that in addition to the furnace shell and cooling stage on the surface of the blast furnace, there are also refractory bricks and a solidified layer formed by the cooling and solidification of the melt in the furnace in the lower part of the furnace. Moreover, refractory bricks deteriorate over the years due to wear and thermal stress, and the range of the solidified layer changes every day depending on the thermal conditions in the lower part of the furnace. Therefore, it is extremely difficult to grasp the existence state of these constituent materials. Therefore, in the method described in Patent Document 2, it is essentially impossible to exclude unknown parameters other than the melt height representing the constituent materials of the blast furnace from the general equation. Therefore, it is difficult to say that the accuracy of the melt height inferred based on the general equation can be satisfied.

[0011] In addition, in the method described in Patent Document 3, a large amount of dust is generated during the discharge of the high-temperature melt during the tapping operation, so the possibility of being able to use a camera to clearly capture the discharge behavior of the melt is low. Moreover, opening errors represented by transverse holes are inevitably generated during the tapping operation, which also contributes to the reduction in the frequency of inference of the discharge behavior of the melt. In addition, the shape of the opening is different each time the iron is tapped, so it is very difficult to quantify the friction force on the path from the furnace to the discharge port. In summary, the method described in Patent Document 3 can be said to be extremely difficult to measure the height of the melt with high precision.

[0012] Furthermore, the method described in Patent Document 4 presents the following issues. The vibration intensity of an actual furnace body is significantly affected by fluctuations in air flow, as well as changes in the shape of structures such as furnace fillings, furnace bottom bricks, and the solidified layer, exceeding the melt height. Therefore, in blast furnace processes where operating conditions fluctuate constantly, it is impossible to establish a one-to-one correlation between furnace body vibration intensity and melt height. Consequently, the method described in Patent Document 4 is effective only under ideal conditions, where furnace conditions other than melt height are stable, making it difficult to achieve long-term, stable melt height measurement. Summary of the Invention

[0013] The present invention has been made to solve the above-mentioned problems, and its object is to provide a method and device for measuring the melt height in a blast furnace that can accurately measure the melt height in the blast furnace regardless of the blast furnace operating conditions. Furthermore, another object of the present invention is to provide a blast furnace operating method that enables stable and eco-friendly blast furnace operation.

[0014] The method for measuring the melt height in a blast furnace involved in the present invention includes: a measuring step, using a plurality of vibrometers arranged at prescribed intervals along the height direction of the furnace body of the blast furnace to measure the vibration frequency distribution in the height direction of the furnace body; a vibration intensity calculating step, calculating the vibration intensity of the frequency range originating from the air supply at each measuring position by performing Fourier transform on the above-mentioned vibration frequency distribution; a numerical analysis step, using a numerical analysis model with the melt height and the air supply volume in the blast furnace as variables to calculate the maximum vibration intensity distribution of the lower part of the blast furnace; and a melt height calculating step, calculating the above-mentioned melt height at which the difference between the vibration intensity calculated in the above-mentioned vibration intensity calculating step and the maximum vibration intensity distribution calculated in the above-mentioned numerical analysis step is minimized, and using the calculated melt height as the position of the melt height in the blast furnace.

[0015] The above-mentioned vibration meter can be set between the height of the iron outlet and the height of the tuyere of the furnace body.

[0016] The frequency range of the above-mentioned air supply may be in the range of 700 to 900 Hz.

[0017] The device for measuring the melt height in a blast furnace involved in the present invention comprises: a plurality of vibrometers arranged at prescribed intervals along the height direction of the furnace body of the blast furnace, for measuring the vibration frequency distribution in the height direction of the furnace body; and an information processing device, for calculating the vibration intensity of the frequency range originating from the air supply at each measurement position by performing Fourier transform on the above-mentioned vibration frequency distribution, calculating the maximum vibration intensity distribution of the lower part of the blast furnace using a numerical analysis model with the melt height and the air supply volume in the blast furnace as variables, calculating the above-mentioned melt height at which the difference between the above-mentioned vibration intensity and the above-mentioned maximum vibration intensity distribution is minimized, and using the calculated melt height as the position of the melt height in the blast furnace.

[0018] The blast furnace operating method according to the present invention includes the step of operating the blast furnace based on the melt height measured using the method for measuring the melt height in the blast furnace according to the present invention.

[0019] The method and device for measuring the melt height in a blast furnace according to the present invention can accurately measure the melt height in the blast furnace regardless of the blast furnace operating conditions. Furthermore, the blast furnace operating method according to the present invention enables stable and eco-friendly blast furnace operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic cross-sectional view showing the structure of a blast furnace to which an apparatus for measuring the level of a melt in a blast furnace, which is one embodiment of the present invention, is applied.

[0021] Figure 2 This is a diagram showing the calculation flow of a numerical analysis model related to vibration.

[0022] Figure 3 is a diagram representing the structure of a computational grid.

[0023] Figure 4 It is a diagram showing an analysis example of a two-dimensional vibration model.

[0024] Figure 5 This is a graph showing the results of plotting the vibration intensity due to air blowing measured by a plurality of vibration meters when the melt height is changed, against the height of the measurement position relative to the melt height.

[0025] Figure 6 This is a graph showing the temporal change in the measured values ​​of the melt height from the initial stage to the final stage of tapping.

[0026] Figure 7 This graph shows the results of fitting the vibration intensity measured using an actual machine and the maximum vibration intensity predicted by the numerical analysis model according to the melt height. DETAILED DESCRIPTION

[0027] Hereinafter, a method for measuring the melt level in a blast furnace, an apparatus for measuring the melt level in a blast furnace, and a blast furnace operating method according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0028] 〔structure〕

[0029] First, refer to Figure 1 The structure of a device for measuring the melt level in a blast furnace according to one embodiment of the present invention will be described.

[0030] Figure 1 1 is a schematic cross-sectional view showing the structure of a blast furnace to which a device for measuring the height of a melt in a blast furnace according to an embodiment of the present invention is applied. Figure 1 As shown, a blast furnace 1 as one embodiment of the present invention comprises: a generally cylindrical furnace body 2; an air supply tuyere (hereinafter referred to as a tuyere) 3 provided below the furnace body 2; and a taphole 4 provided in the furnace body 2 below the tuyere 3. The bottom of the blast furnace 1 is formed of furnace bottom bricks 5 and furnace wall bricks 6, and the inner and outer wall surfaces of the furnace wall bricks 6 are covered by a cooling sleeve 7 and a furnace shell 8, respectively.

[0031] Furthermore, a blast furnace 1, as one embodiment of the present invention, includes a plurality of vibration meters 9, a data logger 10, and an information processing device 11 as devices for measuring the melt level within the blast furnace. Each vibration meter 9 is positioned at equal intervals along a straight line perpendicular to a tangent to the circumference of the furnace body 2 and extending along the surface of the furnace shell 8, from the height of the tap hole 4 to the height of the tuyere 3. Each vibration meter 9 measures the vibration value of the furnace body 2 as a current value and outputs an electrical signal representing the measured current value to the data logger 10.

[0032] The data logger 10 converts the current value measured by each vibration meter 9 into a vibration value based on the electrical signal output from each vibration meter 9. The information processing device 11 calculates the vibration intensity of the furnace body 2 at the location where each vibration meter 9 is installed by performing a Fourier transform on the time-lapse data of the vibration value at the location (measurement location) of each vibration meter 9 generated by the data logger 10. The information processing device 11 then calculates the melt height within the blast furnace by using the calculated vibration intensity to perform the following method for measuring the melt height within the blast furnace.

[0033] The result of the actual machine measurement is that it is confirmed that the vibration of the furnace body 2 has all vibration frequency bands, among which the peak value is particularly high and the vibration with the peak value confirmed at all measurement positions is the frequency band of 700 to 900 Hz. For the vibration in the frequency band of 700 to 900 Hz, since it is confirmed that there is a general trend of showing high values ​​at positions close to the tuyere 3, it is considered to be the vibration caused by the air supply 23 from the tuyere 3 (vibration derived from the air supply). Therefore, in the present invention, the vibration intensity confirmed in the frequency range of 700 to 900 Hz corresponding to the vibration derived from the air supply is used to measure the melt height. However, it is confirmed that the frequency band of the vibration derived from the air supply may vary depending on the shape of the furnace body 2, the influence of the foundation, etc., and there is no conclusive evidence that any blast furnace can be evaluated in the same frequency band. Therefore, when the present invention is expanded to other blast furnaces, it is expected that the basic vibration frequency band analysis will be performed each time.

[0034] exist Figure 1 In the blast furnace 1 shown, raw materials, iron ore 21 and coke 22, are loaded into the furnace body 2 in layers from the furnace top. They are then reduced by blast (hot air) 23, pressure-fed from the tuyere 3, to form a melt 24. The melt 24 then accumulates at the furnace bottom and is discharged from the tap hole 4 as an iron-slag mixture 25 by perforating the tap hole 4 at predetermined intervals. A device for measuring the melt level within a blast furnace, as one embodiment of the present invention, measures the liquid level of the melt 24 at the bottom of the furnace as the melt level.

[0035] [Measurement method]

[0036] Next, refer to Figures 2 to 5A method for measuring the melt height in a blast furnace according to one embodiment of the present invention will be described.

[0037] In a method for measuring the melt height within a blast furnace, one embodiment of the present invention, an information processing device 11 first measures the vibration intensity in the height direction perpendicular to a tangent line in the circumferential direction of the furnace body 2 and executes a numerical analysis model related to vibration to infer the maximum vibration intensity distribution of the furnace body 2. The numerical analysis model requires melt height and air flow rate as input information. However, in this embodiment, the former is treated as a variable used to fit the measured vibration intensity distribution data with the numerical analysis results, while the latter is sequentially obtained from blast furnace operating data. This allows the melt height to be determined by fitting the measured vibration intensity distribution data with the numerical analysis results.

[0038] The numerical analysis model related to vibration is explained. The numerical analysis model related to vibration is a physical model that estimates the maximum vibration intensity distribution in the lower part of the furnace, which is composed of the furnace shell area and the filling layer area. Figure 2 The calculation process of the numerical analysis model related to vibration is shown in FIG. Figure 2 As shown, when executing a numerical analysis model related to vibration, the mesh conditions required for setting up the calculation mesh, the analysis time step, and the density and Young's modulus as physical properties of the furnace shell and filling layer are first set. Furthermore, the air flow rate to the blast furnace 1, considered as a vibration source, is input as an operating specification (step S1).

[0039] Next, if Figure 3 As shown, the information processing device 11 divides a two-dimensional region 31 in the lower portion of the blast furnace 1, which is composed of a furnace shell and a filling layer, into a plurality of element regions 32, defining an axis object (step S2). In this model, each element region 32 is connected by a spring 33 and a damper 34. Acceleration applied to a particular element region 32 is propagated to the surrounding element regions 32 via the spring 33 and the damper 34. The spring 33 represents the restoring force that describes the vibration phenomenon, while the damper 34 represents the attenuation force that causes the vibration energy to disappear due to various energy conversions during the vibration propagation process. Furthermore, in this model, the melt level (melt height) L is taken into account, and the buoyancy and resistance of the melt are applied to the element regions 32 with a center of gravity below the melt level L.

[0040] Return to Figure 2Next, the information processing device 11 calculates the spring constant k of each element region 32 using the mathematical formula (1) shown below (step S3). In the mathematical formula (1), E is the Young's modulus, A is the cross-sectional area of ​​the element region 32 in the direction perpendicular to the spring 33, and L is the length of the element region 32 in the same direction as the spring 33. In this embodiment, the numerical analysis model is a two-dimensional analysis model, so A is the square of the length of the element region 32 perpendicular to the spring 33. In addition, the spring constant k as the material characteristic of each element region 32 is obtained, and the average value of the spring constants k of the two element regions 32 to be combined is given as the spring constant of the spring 33 that combines the element regions 32.

[0041] [Formula 1]

[0042] k=EA / L…(1)

[0043] Next, the information processing device 11 calculates the viscosity coefficient c of each element region 32 using the following mathematical formula (2) (step S4). In mathematical formula (2), m represents the mass of each element region 32. The volume of each element region 32 is given as the product of A and L. In addition, the viscosity coefficient c is calculated as a material property of each element region 32, and the average value of the viscosity coefficients c of the two connected element regions 32 is given as the viscosity coefficient of the damper 34 connecting the element regions 32.

[0044] [Formula 2]

[0045]

[0046] Next, the information processing device 11 uses the processing results of steps S2 and S3 to create a vibration equation based on vibration engineering theory for each element area 32 as shown in the following mathematical formula (3) (step S5). In mathematical formula (3), x represents the displacement of each element area 32, t represents time, and C d represents the liquid resistance, F represents the buoyancy and air supply external force. In addition, if Figure 3 As shown, the subscript I represents the radial position of the two-dimensional region 31, and the subscript J represents the height position of the two-dimensional region 31.

[0047] [Formula 3]

[0048]

[0049] The above mathematical formula (3) is based on Newton's equation of motion. The left side takes into account the inertial force of each element area 32, and the right side takes into account the restoring force, damping force, liquid resistance, buoyancy, and external force of airflow acting on each element area 32. In addition, the formula is created under the assumption that the restoring force is proportional to the magnitude of the displacement of each element area 32 and the damping force is proportional to the speed of each element area 32. In addition, the liquid resistance C d The Kozeny-Carman formula is used to calculate the external air supply force as the product of the pressure loss before the air inlet calculated by the Ergun formula and the surface area of ​​the raceway calculated based on the depth inference formula of the raceway.

[0050] It is known that a general solution of the differential equation of the above-mentioned mathematical formula (3) is represented by the following mathematical formula (4): a represents the maximum acceleration of each element region 32, i represents an imaginary unit, and ω represents the vibration frequency.

[0051] [Formula 4]

[0052] x=ae iωt …(4)

[0053] Therefore, if the mathematical formula (4) is substituted into the mathematical formula (3) and the maximum acceleration a is rearranged, the mathematical formula (5) shown below is obtained.

[0054] [Formula 5]

[0055] [0.5(k I，J-1 +k I，J )]·a I，J-1 +[0.5iω(d I-1，J +d I，J )+0.5(k I-1，J +k I，J )]·a I-1，j +[mω 2 -iωC d -0.5iω(d I-1，J +2d I，J +d I+1，J )-0.5(k I，J-1 +k I-，J +4k I，J +k I+1，J +k I，J+1 )]·a I，J +[0.5iω(d I，J +d I+1，J )+0.5(k I，J +k I+1，J )]·a I+1，j +[0.5(k I，J +k I，J+1 )]·a I，J+1

[0056] =-F I，J

[0057] …(5)

[0058] The above mathematical formula (5) is an equation related to the maximum acceleration of the element area 32 represented by the coordinates of interest (I, J) and the four element areas 32 around it. If the above mathematical formula (5) is created for all element areas 32, it becomes a simultaneous equation related to the maximum acceleration a of all element areas 32. The maximum acceleration a of each element area 32 can be calculated by solving it using the BiCG-Stab method. Therefore, the information processing device 11 calculates the maximum acceleration a of each element area 32, and substitutes the calculated maximum acceleration a into the mathematical formula (4), thereby calculating the maximum vibration intensity distribution of the furnace body 2 (step S6). Then, the information processing device 11 repeatedly performs this process until the maximum vibration intensity distribution of the furnace body 2 reaches a stable state (step S7). In this embodiment, the average value of the measured vibration frequency of 700 to 900 Hz from the air supply, that is, 800 Hz, is set as the vibration frequency ω.

[0059] According to the above, the maximum vibration intensity distribution of the lower part of the furnace, which is composed of the furnace shell and the filling layer, can be inferred based on the vibration engineering theory, but the melt height remains as an unknown parameter. The range of liquid resistance and buoyancy in mathematical formula (3) changes due to the setting of the melt height, so the melt height also affects the calculation result of the maximum vibration intensity distribution. Therefore, next, the information processing device 11 uses the melt height as a variable and determines the melt height in a manner that minimizes the error between the vibration intensity distribution measured multiple times in the height direction of the furnace body 2 and the maximum vibration intensity distribution inferred by this numerical analysis model. Thus, regardless of the operating conditions of the blast furnace, the melt height in the blast furnace can be measured with high precision. In addition, the rise in the melt height can be detected in advance, and the increase in the reduced material ratio caused by the increase in ventilation resistance due to the increase in the melt height can be prevented before it happens, thereby enabling stable and eco-friendly blast furnace operation.

[0060] Figure 4 This shows an analysis example of a two-dimensional vibration model. Figure 4 As shown, it can be confirmed that the following situation: the air supply vibration generated in the vortex zone space where the coke burns violently and is constrained by the air supply pressure gradually dissipates energy and decays during the process of propagating to the surrounding area. Figure 4 In the analysis example shown, it can be confirmed that although it is assumed that the melt surface exists in the region of 2 / 3 of the distance from the furnace bottom to the tuyere 3, the vibration intensity is discontinuously attenuated at the interface. Figure 5The results are obtained by plotting the vibration intensity from the blown air measured by a plurality of vibrometers 9 against the height of the relative measurement position of the vibrometer 9 relative to the melt height (the vibrometer height based on the liquid level) when the melt height is changed using a cold model simulating the lower part of the blast furnace 1. Figure 5 As shown in the figure, the vibration intensity caused by the air supply varies discontinuously on the surface of the melt. Figure 4 The results of the numerical analysis model shown are qualitatively consistent. In addition, this experiment includes the results of multiple scenarios that simulate factors that can change in an actual blast furnace, such as the physical properties of the melt, air supply volume, filling particle size, and particle size distribution of the filling particles. However, none of the scenarios overturned the results. Figure 5 Furthermore, even in experiments that simulated factors that are considered to be interference-generated vibration fluctuations, such as vibrations during raw material charging, changes in the total weight of the furnace filling due to changes in the ratio of reduced materials in the blast furnace, structural changes due to aging caused by wear of furnace bottom bricks, and the installation conditions of the furnace body, the same trend was confirmed. Figure 5 According to the above, it is believed that Figure 5 The discontinuous fluctuation in vibration intensity on the melt surface observed in FIG is a phenomenon that can be uniformly observed under all operating conditions.

[0061] Example

[0062] In this embodiment, the capacity is about 5000m 3 In a large blast furnace, pulverized coal was injected through the tuyere using a standard charge material. Vibrometers were installed at equal intervals on a line perpendicular to the circumferential tangent of the furnace body, extending from the taphole (2 m) to the tuyere. The molten material level within the blast furnace was measured. Table 1 shows the operating conditions for Examples 1 and 2. Figure 6 The time variation of the measured value of the melt height from the initial stage of tapping to the final stage of tapping is shown. Figure 7 The results of fitting the vibration intensity measured by the actual machine and the maximum vibration intensity estimated by the numerical analysis model according to the melt height are shown. Figure 6 As shown in FIG. 1 , the melt height of Examples 1 and 2 is finally equal to the tap hole height. Thus, according to the present invention, it is confirmed that the melt height can be measured with high precision. Figure 7 As shown in (a), at the beginning of tapping, the molten material height is set to about 4.0m, so that the difference between the actual value and the estimated value is the smallest. Figure 7 As shown in (b), at the end of tapping, the height of the remaining slag is set to 2.0 m, so that the difference between the actual value and the estimated value is minimized.

[0063] [Table 1]

[0064] (Table 1)

[0065] Example 1 Example 2 Coke ratio (kg / t) 345 330 Pulverized coal ratio (kg / t) 220 235 Reducing material ratio (kg / t) 565 565 Iron output (t / d) 9698 9712 Iron tapping temperature (℃) 1524 1526

[0066] While the embodiments of the invention developed by the present inventors have been described above, the present invention is not limited to the description and drawings that constitute part of the disclosure of the invention based on these embodiments. In other words, other embodiments, examples, and application techniques developed by those skilled in the art based on these embodiments are all within the scope of the present invention.

[0067] Industrial applicability

[0068] According to the present invention, a method and device for measuring the melt height in a blast furnace can be provided, which can accurately measure the melt height in the blast furnace regardless of the blast furnace operating conditions. Furthermore, according to the present invention, a blast furnace operating method can be provided, which can stably and eco-friendlyly operate the blast furnace.

[0069] Description of Reference Numerals

[0070] 1… blast furnace; 2… furnace body; 3… air duct and tuyere; 4… taphole; 5… furnace bottom bricks; 6… furnace wall bricks; 7… cooling sleeve; 8… furnace shell; 9… vibration meter; 10… data recorder; 11… information processing device; 21… iron ore; 22… coke; 23… air duct; 24… melt; 25… iron-slag mixture; 31… two-dimensional region; 32… element region; 33… spring; 34… damper.

Claims

1. A method for measuring the height of a melt in a blast furnace, characterized in that: include: a measuring step of measuring a vibration frequency distribution in the height direction of the furnace body using a plurality of vibrometers arranged at predetermined intervals along the height direction of the furnace body of the blast furnace; a vibration intensity calculation step of calculating the vibration intensity of the frequency range originating from the blown air at each measurement position by performing Fourier transform on the vibration frequency distribution; a numerical analysis step of calculating a maximum vibration intensity distribution in a lower portion of the blast furnace using a numerical analysis model with a melt height and an air supply rate in the blast furnace as variables; and The melt height calculation step calculates the melt height at which the difference between the vibration intensity calculated in the vibration intensity calculation step and the maximum vibration intensity distribution calculated in the numerical analysis step is minimized, and uses the calculated melt height as the position of the melt height in the blast furnace.

2. The method for measuring the melt height in a blast furnace according to claim 1, wherein: The vibration meter is arranged between the height of the iron outlet and the height of the tuyere of the furnace body.

3. The method for measuring the melt height in a blast furnace according to claim 1 or 2, characterized in that: The frequency range of the air supply is within the range of 700 to 900 Hz.

4. A device for measuring the height of a melt in a blast furnace, characterized in that: have: a plurality of vibrometers are arranged at predetermined intervals along the height direction of the furnace body of the blast furnace to measure the vibration frequency distribution in the height direction of the furnace body; and An information processing device calculates the vibration intensity of the frequency range originating from the air supply at each measuring position by performing Fourier transform on the vibration frequency distribution, calculates the maximum vibration intensity distribution of the lower part of the blast furnace using a numerical analysis model with the melt height and the air supply volume in the blast furnace as variables, calculates the melt height at which the difference between the vibration intensity and the maximum vibration intensity distribution is minimized, and uses the calculated melt height as the position of the melt height in the blast furnace.

5. A method for operating a blast furnace, characterized in that: The steps include: The blast furnace is operated based on the melt level measured using the method for measuring the melt level in a blast furnace according to claim 1 or 2.

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