A method for evaluating the permeability of blast furnace soft melting zone

Abstract

The present invention discloses a method for evaluating the air permeability of a blast furnace soft melting zone. According to the cross temperature measurement data of the blast furnace and the radial position of the furnace throat, a shape function of the cross temperature measurement is obtained by using polynomial fitting; according to the shape function of the cross temperature measurement, a shape function of the soft melting zone is obtained by using coordinate transformation; according to the focus window position and shape function of the soft melting zone, the diameter of each layer of the focus window inside the soft melting zone is obtained; according to the focus window diameter and thickness, the focus window area is calculated; the air permeability of the soft melting zone is characterized by the ratio of the total area of ​​the focus window of the soft melting zone to the cross-sectional area of ​​the furnace waist, and the air permeability index of the soft melting zone is calculated. The present invention characterizes the air permeability of the soft melting zone by the ratio of the total area of ​​the focus window of the soft melting zone to the cross-sectional area of ​​the furnace waist. This method is simple and effective, and is convenient for production operators to calculate and analyze.

Description

Technical Field

[0001] The invention relates to a permeability evaluation method, in particular to a blast furnace soft melting zone permeability evaluation method, belonging to the technical field of blast furnace ironmaking. Background Art

[0002] The soft melting zone is composed of coke and molten ore. The coke and ore are distributed in layers, and the coal gas mainly passes through the coke layer. Therefore, the soft melting zone is the area with the worst permeability in the blast furnace. Studies have shown that the pressure loss in the soft melting zone accounts for more than 50% of the total pressure difference of the blast furnace. Therefore, the permeability of the soft melting zone has a huge impact on the operation status of the blast furnace. Since the blast furnace is a black box, many parameters are difficult to quantify. In the prior art, no evaluation index has been established for the permeability of the soft melting zone. Therefore, it is necessary to design an evaluation method for the permeability of the blast furnace soft melting zone, so as to evaluate the permeability of the blast furnace soft melting zone to better monitor the operation status of the blast furnace. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for evaluating the permeability of a blast furnace soft melting zone, wherein the permeability of the soft melting zone is characterized by the ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for evaluating the air permeability of a blast furnace soft melting zone, characterized by comprising the following steps:

[0006] Step 1: Based on the blast furnace cross temperature measurement data and the radial position of the furnace throat, the shape function of the cross temperature measurement is obtained by polynomial fitting;

[0007] Step 2: Based on the shape function of the cross temperature measurement, the shape function of the soft melting zone is obtained by coordinate transformation;

[0008] Step 3: According to the focal window position and shape function of the soft melting zone, the diameter of each focal window inside the soft melting zone is obtained;

[0009] Step 4: Calculate the focal window area based on the focal window diameter and thickness;

[0010] Step 5: Use the ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist to characterize the permeability of the soft melting zone and calculate the permeability index of the soft melting zone.

[0011] Furthermore, the step 1 is specifically as follows:

[0012] The average temperature T of the cross temperature measurement at the throat position within the set time beam,j , j = 1, 2, ... k, where j = 1 represents the edge, j = k represents the center, and the corresponding throat radial position x beam,j, using polynomial fitting we can get:

[0013] T beam =f(x beam ) (1)

[0014] In the formula, x beam It indicates the radial position of the furnace throat at each point of the cross temperature measurement. The center point of the furnace throat is the coordinate origin. The horizontal axis is the furnace throat diameter and the vertical axis is the temperature displayed by the cross temperature measurement. f(x beam ) is a polynomial function of the throat radial position and temperature.

[0015] Furthermore, the step 2 is specifically as follows:

[0016] Establish a soft melting zone shape coordinate system, with the origin of the coordinate system being the center point of the bottom of the soft melting zone, the horizontal axis being the bottom diameter, and the vertical axis being the height of the soft melting zone, which is represented by the position of the material line;

[0017]

[0018]

[0019] Where D T is the furnace throat diameter; D L x is the furnace diameter at the lowest point of the soft melting zone; cohesive is the independent variable of the shape function of the soft melting zone, indicating the radial position of the soft melting zone; t d h is the soft melting temperature of the ore; sl h is the dependent variable of the shape function of the soft melting zone, indicating the longitudinal position of the soft melting zone, which is the depth of the material line here; sl,λ is the position of the material line at the root of the soft melting zone, which can be calculated based on the static pressure distribution of the blast furnace or the temperature distribution of the cooling wall; T beam,1 is the cross temperature measurement edge temperature;

[0020] Substituting formulas (2) and (3) into the cross temperature measurement shape function (1), the shape function of the soft melting zone can be obtained:

[0021]

[0022] Furthermore, the step three is specifically as follows:

[0023] The material line position h of each focal window is calculated based on the batch volume and the material line position at the bottom of the soft melting zone. sl,i , i = 1, 2, 3...n, where n is the number of focus windows in the soft melting zone, and the radial position corresponding to the material line position of each focus window is x cohesive,i , then the diameter of the inner focal window inside the soft melting zone is:

[0024] D cohesive,i =2·|x cohesive,i |

[0025] (5).

[0026] Furthermore, the step 4 is specifically as follows:

[0027] Calculate the focal window area based on the focal window diameter and thickness:

[0028]

[0029] Where, L i is the thickness of the i-th layer focal window, which is calculated based on the coke batch volume and the material line position.

[0030] Furthermore, the step five is specifically as follows:

[0031] The ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist is used to characterize the permeability:

[0032]

[0033] Where, K is the air permeability index of the soft melting belt. The larger the K value, the better the air permeability of the soft melting belt. c S is the coke window area of ​​the blast furnace soft melting zone; b is the cross-sectional area of ​​the blast furnace waist.

[0034] Compared with the prior art, the present invention has the following advantages and effects: the evaluation method of the blast furnace soft melting zone permeability of the present invention characterizes the soft melting zone permeability by the ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist. This method is simple and effective, and is convenient for production operators to calculate and analyze. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flow chart of a method for evaluating the air permeability of a blast furnace soft melting zone.

[0036] Figure 2 It is a schematic diagram of the shape and parameters of the soft melting zone in the furnace according to an embodiment of the present invention.

[0037] Figure 3 Schematic diagram of cross temperature measurement temperature distribution in an embodiment of the present invention.

[0038] Figure 4 It is a schematic diagram of the distribution of the focal window area in the soft melting zone of the furnace according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to elaborate on the technical scheme adopted by the present invention to achieve the predetermined technical purpose, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments, and the technical means or technical features in the embodiments of the present invention can be replaced without paying creative work. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0040] like Figure 1 As shown, a method for evaluating the air permeability of a blast furnace soft melting zone of the present invention comprises the following steps:

[0041] Step 1: Based on the blast furnace cross temperature measurement data and the radial position of the furnace throat, the shape function of the cross temperature measurement is obtained by polynomial fitting.

[0042] The average temperature T of the cross temperature measurement at the throat position within the set time beam,j , j = 1, 2, ... k, where j = 1 represents the edge, j = k represents the center, and the corresponding throat radial position x beam,j , using polynomial fitting we can get:

[0043] T beam =f(x beam ) (1)

[0044] In the formula, x beam It indicates the radial position of the furnace throat at each point of the cross temperature measurement. The center point of the furnace throat is the coordinate origin. The horizontal axis is the furnace throat diameter and the vertical axis is the temperature displayed by the cross temperature measurement. f(x beam ) is a polynomial function of the throat radial position and temperature.

[0045] Figure 3 The cross temperature measurement temperature distribution, the furnace throat diameter is 8.2m, -4.2m≤x beam ≤4.2m, the first point of the cross temperature measurement is 300mm away from the furnace wall, and the cross temperature measurement is fitted using a polynomial, requiring the R square value to be greater than 0.98, and the calculation results are:

[0046]

[0047] Step 2: Based on the shape function of the cross temperature measurement, the shape function of the soft melting zone is obtained by coordinate transformation.

[0048] Establish a soft melting zone shape coordinate system, with the origin of the coordinate system being the center point of the bottom of the soft melting zone, the horizontal axis being the bottom diameter, and the vertical axis being the height of the soft melting zone, which is represented by the position of the material line;

[0049]

[0050]

[0051] Where D T is the furnace throat diameter; D L x is the furnace diameter at the lowest point of the soft melting zone; cohesive is the independent variable of the soft melting zone shape function, indicating the radial position of the soft melting zone, t d h is the soft melting temperature of the ore; sl h is the dependent variable of the shape function of the soft melting zone, indicating the longitudinal position of the soft melting zone, which is the depth of the material line here; sl,λ is the position of the material line at the root of the soft melting zone, which can be calculated based on the static pressure distribution of the blast furnace or the temperature distribution of the cooling wall; T beam,1 is the edge temperature of the cross temperature measurement.

[0052] In this embodiment, D L The example value of is 13.1m. d The example value is 1400℃. sl,λ According to the example, the temperature distribution of the cooling wall is calculated to be 18.9m.

[0053] Substituting formulas (2) and (3) into the cross temperature measurement shape function (1), the shape function of the soft melting zone can be obtained:

[0054]

[0055] In this embodiment,

[0056]

[0057] Step 3: According to the focal window position and shape function of the soft melting zone, the diameter of each focal window layer inside the soft melting zone is obtained.

[0058] like Figure 2 As shown in the figure, the material line position h of each focal window is calculated based on the batch volume and the material line position at the bottom of the soft melting zone. sl,i , i = 1, 2, 3...n, where n is the number of focus windows in the soft melting zone, and the radial position corresponding to the material line position of each focus window is x cohesive,i , then the diameter of the inner focal window inside the soft melting zone is:

[0059] D cohesive,i =2|x cohesive,i | (5).

[0060] Known feed line position h sl,i Then, the shape function of the soft melting zone is introduced and the equation can be solved by the dichotomy method.

[0061] Step 4: Calculate the focal window area based on the focal window diameter and thickness:

[0062]

[0063] Where, L i is the thickness of the i-th layer focal window, which is calculated based on the coke batch volume and the material line position.

[0064] Step 5: Calculate the permeability index of the soft melting zone. The permeability is characterized by the ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist:

[0065]

[0066] Where, K is the air permeability index of the soft melting belt. The larger the K value, the better the air permeability of the soft melting belt. c S is the coke window area of ​​the blast furnace soft melting zone; b It is the cross-sectional area of ​​the blast furnace waist, which can be calculated from the furnace size.

[0067] Figure 4 To calculate the focal window area of ​​each layer of the soft melting zone, the sum of the focal window areas is the total focal window area of ​​the soft melting zone. Further, the permeability index of the soft melting zone can be calculated based on the cross-sectional area of ​​the furnace waist.

[0068] The evaluation method of the blast furnace soft melting zone permeability of the present invention characterizes the soft melting zone permeability by the ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist. The method is simple and effective, and is convenient for production operators to calculate and analyze.

[0069] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for evaluating the permeability of a blast furnace soft melting zone, characterized in that The following steps are involved: Step 1: Based on the blast furnace cross temperature measurement data and the radial position of the furnace throat, the shape function of the cross temperature measurement is obtained by polynomial fitting; The step 1 is specifically as follows: The average temperature T of the cross temperature measurement at the throat position within the set time beam,j , j = 1, 2, ... k, where j = 1 represents the edge, j = k represents the center, and the corresponding throat radial position x beam,j , using polynomial fitting we can get: T beam =f(x beam ) (1) In the formula, x beam Indicates the radial position of the furnace throat at each point of the cross temperature measurement. The center point of the furnace throat is the coordinate origin. The horizontal axis is the furnace throat diameter and the vertical axis is the temperature displayed by the cross temperature measurement. f(x beam ) is a polynomial function of throat radial position and temperature; Step 2: Based on the shape function of the cross temperature measurement, the shape function of the soft melting zone is obtained by coordinate transformation; The step 2 is specifically as follows: Establish a soft melting zone shape coordinate system, with the origin of the coordinate system being the center point of the bottom of the soft melting zone, the horizontal axis being the bottom diameter, and the vertical axis being the height of the soft melting zone, which is represented by the position of the material line; Where D T is the furnace throat diameter; D L x is the furnace diameter at the lowest point of the soft melting zone; cohesive is the independent variable of the shape function of the soft melting zone, indicating the radial position of the soft melting zone; t d h is the soft melting temperature of the ore; sl h is the dependent variable of the shape function of the soft melting zone, indicating the longitudinal position of the soft melting zone, which is the depth of the material line here; sl,λ is the position of the material line at the root of the soft melting zone, which can be calculated based on the static pressure distribution of the blast furnace or the temperature distribution of the cooling wall; T beam,1 is the cross temperature measurement edge temperature; Substituting formulas (2) and (3) into the cross temperature measurement shape function (1), the shape function of the soft melting zone can be obtained: Step 3: According to the focal window position and shape function of the soft melting zone, the diameter of each focal window inside the soft melting zone is obtained; The step three is specifically as follows: The material line position h of each focal window is calculated based on the batch volume and the material line position at the bottom of the soft melting zone. sl,i , i = 1, 2, 3...n, where n is the number of focus windows in the soft melting zone, and the radial position corresponding to the material line position of each focus window is x cohesive,i , then the diameter of the inner focal window inside the soft melting zone is: D cohesive,i =2·|x cohesive,i | (5); Step 4: Calculate the focal window area based on the focal window diameter and thickness; The step 4 is specifically as follows: Calculate the focal window area based on the focal window diameter and thickness: Where, L i is the thickness of the i-th layer focal window, which is calculated based on the coke batch volume and the position of the material line; Step 5: The ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist is used to characterize the permeability of the soft melting zone, and the permeability index of the soft melting zone is calculated; The step five is specifically as follows: The ratio of the total area of ​​the soft melting zone coke window to the cross-sectional area of ​​the furnace waist is used to characterize the permeability: In the formula, K is the air permeability index of the soft melting belt. The larger the K value, the better the air permeability of the soft melting belt. S c is the coke window area of ​​the blast furnace soft melting zone; S b is the cross-sectional area of ​​the blast furnace waist.

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