Carbon brick residual thickness calculation method based on single-point hearth brick lining temperature measurement

Abstract

The invention relates to a carbon brick residual thickness calculation method based on single-point hearth brick lining temperature measurement, the carbon brick residual thickness is calculated according to a thermodynamic Fourier formula, and the method comprises the following steps: S1, estimating the carbon brick hot surface temperature T2 initial under different carbon brick residual thicknesses; s2, according to the estimated T2, preliminarily determining the residual thickness range of the carbon brick in combination with a blast furnace hearth carbon brick hot surface temperature empirical value; s3, according to the corresponding heat conductivity coefficients measured in the laboratory under different temperature conditions, the carbon brick hot surface temperatures under different carbon brick residual thicknesses are calculated again; s4, determining the residual thickness range of the carbon brick again according to the temperature value calculated in the step S3, calculating the heat conductivity coefficients corresponding to different residual thicknesses of the carbon brick under the temperature value calculated in the step S3 in the residual thickness range of the carbon brick, and averaging the heat conductivity coefficients; and calculating the residual thickness of the carbon brick by using a thermodynamic Fourier formula. The method has the advantage that the residual thickness of the carbon brick can be calculated under the condition that only one normal couple is left at the same position of the blast furnace hearth brick lining.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnace smelting, and in particular relates to a carbon brick residual thickness calculation method based on single-point furnace brick lining temperature measurement. Background Art

[0002] In steel enterprises, the main problems of blast furnaces are high efficiency and longevity, and longevity is the key to the sustainable development of ironmaking. Extending the life of blast furnaces can not only save hundreds of millions of yuan in overhaul costs, but also improve the production efficiency of blast furnaces, reduce fixed costs in costs, thereby reducing production costs and improving corporate competitiveness. According to incomplete statistics, since 2003, more than 30 blast furnaces across the country have experienced hearth burnout accidents, causing significant economic losses to enterprises, and some even causing personal injury accidents. In order to ensure the safe production of blast furnace hearths, avoid hearth burnout accidents, and extend the life of blast furnaces, it is particularly important to accurately judge the degree of erosion of hearth brick linings. That is, the residual thickness of the hearth brick lining is obtained through thermodynamic calculations, and effective furnace protection measures are taken in time according to the degree and trend of brick lining erosion, to promote the formation of the hearth protective layer and slow down the erosion rate of the hearth brick lining. The installation method of the furnace brick lining thermocouple is a one-hole double-branch or three-branch thermocouple. The current calculation method requires the temperature data of two or more thermocouples at the same position of the furnace brick lining, and the residual thickness of the brick lining is calculated by the Fourier formula. For example, patent application number: CN201810789527.5 discloses a method for judging the residual thickness of carbon bricks in a blast furnace hearth.

[0003] In actual blast furnace production, due to various reasons, the furnace brick lining couple is damaged, and only one couple at the same position of the brick lining is normal, that is, only one point in a couple hole shows normal temperature. In this case, the traditional method cannot calculate the residual thickness of the brick lining here. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for calculating the residual thickness of carbon bricks based on single-point furnace cylinder brick lining temperature measurement, which can calculate the residual thickness of carbon bricks when only one normal thermocouple remains at the same position of the blast furnace furnace brick lining.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement comprises the following steps:

[0007] S1: Based on the thermal conductivity of the furnace carbon brick design and the corresponding thermal conductivity under different temperature conditions measured in the laboratory, the thermal conductivity of the carbon brick at a certain temperature is first assumed, and the single-point couple temperature T1 of the carbon brick is substituted by the thermodynamic Fourier formula to estimate the hot surface temperature of the carbon brick under different residual thicknesses of the carbon brick;

[0008] S2: Based on the hot surface temperature of carbon bricks at different residual thicknesses estimated by S1 and the empirical value of hot surface temperature of carbon bricks in the blast furnace hearth, the range of residual thickness of carbon bricks is preliminarily determined;

[0009] S3: Calculate the hot surface temperature of carbon bricks under different residual thicknesses again according to the corresponding thermal conductivity under different temperature conditions measured in the laboratory;

[0010] S4: according to the calculation result of S3, the range of residual thickness of carbon bricks is determined again. Within this range of residual thickness of carbon bricks, the thermal conductivity corresponding to different residual thickness of carbon bricks at the hot surface temperature of carbon bricks under different residual thickness of carbon bricks described in S3 is calculated, and the average value of thermal conductivity is taken;

[0011] S5: Using the average value of thermal conductivity obtained in S4, the residual thickness of the carbon brick is finally calculated.

[0012] The residual thickness of carbon bricks in S1 increases in units of 100 mm. The empirical value of the hot surface temperature of carbon bricks in the blast furnace hearth described in S2 is 800-1550°C. The hot surface temperature range of carbon bricks under different residual thicknesses of carbon bricks estimated in S1 is greater than 800-1550°C, otherwise the range of the residual thickness of carbon bricks is expanded.

[0013] The thermodynamic Fourier formula is:

[0014] L=L1+L2=L1+(T2-T1)*λ / q (1)

[0015] In formula (1), L is the residual thickness of carbon brick, m; T1 is the internal temperature of carbon brick, °C; T2 is the hot surface temperature of carbon brick, °C; L1 is the distance between the internal temperature measuring point of carbon brick and the cold surface of carbon brick, m; L2 is the distance between the internal temperature measuring point of carbon brick and the hot surface of carbon brick, m; λ is the thermal conductivity of carbon brick, w / (m·℃); q is the heat flux intensity of furnace cooling wall, kw / m 2 .

[0016] S1 estimates the hot surface temperature T of carbon bricks at different residual thicknesses 2初 :

[0017] T 2初 = T 1初 +q*(L 估 -L 1初 ) / λ 测 (2)

[0018] In formula (2): 测 is the measured value of thermal conductivity of carbon brick, w / (m·℃); L 1初 is the initial design value of the distance between the thermocouple temperature measuring point inside the carbon brick and the cold surface of the carbon brick, m; T 2初 is the estimated range of carbon brick hot surface temperature, ℃; T 1初is the internal design temperature of the carbon brick, ℃; L 估 is the estimated residual thickness of carbon bricks, m; the calculation formula of the heat flux intensity q of the furnace cooling wall is:

[0019]

[0020] In formula (3), w1 is the furnace cooling wall water pipe flow rate corresponding to the location of the thermocouple temperature measurement point inside the carbon brick, m 3 / h, which can be obtained by reading the flow meter installed on the furnace cooling wall water pipe; t1 and t2 are the actual measured temperature values ​​of the thermometers installed at the inlet and outlet of the furnace cooling wall water pipe, ℃; d is the outer diameter of the furnace cooling wall water pipe, m; h is the length of the furnace cooling wall water pipe, m.

[0021] In S2, the empirical value range of the hot surface temperature of carbon bricks in the blast furnace hearth is taken from the carbon brick hot surface temperature range value estimated in S1, and the carbon brick residual thickness range corresponding to the empirical value range of the hot surface temperature of carbon bricks in the blast furnace hearth is preliminarily determined in the carbon brick residual thickness range estimated in S1.

[0022] Calculation of hot surface temperature of carbon bricks at different residual thickness of carbon bricks as described in S3:

[0023]

[0024] In formula (4) and (5), q is the heat flux intensity of the furnace cooling wall, kw / m 2 ; i T 1i Thermal conductivity of carbon brick at temperature, w / (m.℃); T 1i is the internal couple temperature of carbon brick at different temperatures, °C; T 2i is the hot surface temperature of the carbon brick at different temperatures, ℃; L1 is the distance between the internal thermocouple temperature measuring point of the carbon brick and the cold surface of the carbon brick, m; L2 is the distance between the internal thermocouple temperature measuring point of the carbon brick and the hot surface of the carbon brick.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention can calculate the residual thickness of carbon bricks when only one normal electric couple remains at the same position of the blast furnace hearth brick lining and the traditional method cannot calculate the degree of carbon brick erosion. The residual thickness of carbon bricks obtained by the method of the present invention guides the blast furnace operator to take effective furnace protection measures in time to avoid the blast furnace hearth burning through and extend the life of the blast furnace. DETAILED DESCRIPTION

[0027] The present invention is described in detail below, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0028] A method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement comprises the following steps:

[0029] S1: According to the designed thermal conductivity of the furnace hearth carbon bricks and the corresponding thermal conductivity under different temperature conditions measured in the laboratory, first assume the thermal conductivity of the carbon bricks at a certain temperature, use the thermodynamic Fourier formula, substitute the single-point electric couple temperature T1 of the carbon bricks, and estimate the hot surface temperature of the carbon bricks under different residual thicknesses of the carbon bricks; among them, the residual thickness of the carbon bricks increases in units of 100mm, and the empirical value of the hot surface temperature of the blast furnace hearth carbon bricks described in S2 is 800-1550℃. The hot surface temperature range of the carbon bricks under different residual thicknesses of the carbon bricks estimated in S1 is greater than 800-1550℃, otherwise the value range of the residual thickness of the carbon bricks is expanded.

[0030] S2: Based on the hot surface temperature of carbon bricks at different residual thicknesses estimated by S1 and the empirical value of the hot surface temperature of carbon bricks in the blast furnace hearth, the range of residual thickness of carbon bricks is preliminarily determined.

[0031] S3: Calculate the hot surface temperature of carbon bricks under different residual thicknesses again according to the corresponding thermal conductivity under different temperature conditions measured in the laboratory;

[0032] S4: according to the calculation result of S3, the range of residual thickness of carbon bricks is determined again. Within this range of residual thickness of carbon bricks, the thermal conductivity corresponding to different residual thickness of carbon bricks at the hot surface temperature of carbon bricks under different residual thickness of carbon bricks described in S3 is calculated, and the average value of thermal conductivity is taken;

[0033] S5: Using the average value of thermal conductivity obtained in S4, the residual thickness of the carbon brick is finally calculated.

[0034] The specific calculation method of carbon brick residual thickness based on single-point furnace brick lining temperature measurement is to calculate the carbon brick residual thickness according to the thermodynamic Fourier formula:

[0035] L=L1+L2=L1+(T2-T1)* λ / q (1)

[0036] In formula (1), L is the residual thickness of carbon brick, mm; T1 is the internal temperature of carbon brick, °C; T2 is the hot surface temperature of carbon brick, °C; L1 is the distance between the internal temperature measuring point of carbon brick and the cold surface of carbon brick, mm; L2 is the distance between the internal temperature measuring point of carbon brick and the hot surface of carbon brick, mm; λ is the thermal conductivity of carbon brick, w / (m·℃); q is the heat flux intensity of furnace cooling wall, kw / m 2 , specifically including the following steps:

[0037] S1 estimates the residual thickness L of carbon bricks using the thermodynamic Fourier formula based on the measured value of thermal conductivity of carbon bricks 估 And the temperature range of the hot surface of the carbon brick is T 2初 ;

[0038] T 2初 = T 1初+q*(L 估 -L 1初 ) / λ 测 (2)

[0039] In formula (2): 测 is the measured value of thermal conductivity of carbon brick; L 1初 is the initial design value of the distance between the thermocouple temperature measuring point inside the carbon brick and the cold surface of the carbon brick; T 2初 T is the estimated range of carbon brick hot surface temperature; 1初 is the internal design temperature of the carbon brick; the calculation formula of the heat flux intensity q of the furnace cooling wall is:

[0040]

[0041] In formula (3), w1 is the furnace cooling wall water pipe flow rate corresponding to the location of the thermocouple temperature measurement point inside the carbon brick, m 3 / h, which can be obtained by reading the flow meter installed on the furnace cooling wall water pipe; t1 and t2 are the actual measured temperature values ​​of the thermometer installed at the inlet and outlet of the furnace cooling wall water pipe, ℃; d is the outer diameter of the furnace cooling wall water pipe, m; h is the length of the furnace cooling wall water pipe, m;

[0042] S2 takes the conventional carbon brick hot surface temperature range value from the carbon brick hot surface temperature range value estimated by S1, and preliminarily determines the carbon brick residual thickness range corresponding to the conventional carbon brick hot surface temperature range value in the carbon brick residual thickness range estimated by step 1);

[0043] S3 accurately calculates the hot surface temperature of the carbon brick according to the thermal conductivity of the carbon brick at different temperatures and the corresponding residual thickness of the carbon brick preliminarily determined by S2;

[0044]

[0045] In formula (4) and (5), q is the heat flux intensity of the furnace cooling wall, kw / m 2 ; i T 1i Thermal conductivity of carbon brick at temperature, w / (m·℃); T 1i is the internal couple temperature of carbon brick at different temperatures, °C; T 2i is the hot surface temperature of the carbon brick at different temperatures, °C; L1 is the distance between the thermocouple temperature measuring point inside the carbon brick and the cold surface of the carbon brick, mm; L2 is the distance between the thermocouple temperature measuring point inside the carbon brick and the hot surface of the carbon brick;

[0046] S4: the carbon brick residual thickness corresponding to the temperature at which embrittlement and alkali metal chemical corrosion start in the carbon brick hot surface temperature calculated by S3 is selected as the minimum carbon brick residual thickness value; the carbon brick residual thickness corresponding to the temperature at which molten iron starts to flow freely in the carbon brick hot surface temperature calculated by step 3) is selected as the maximum carbon brick residual thickness value; within this range, the thermal conductivity is calculated according to the hot surface temperature of the carbon brick at different temperatures, and the average value is taken;

[0047] S5 uses the average thermal conductivity of the carbon bricks obtained in S4, and finally calculates the residual thickness of the carbon bricks using the thermodynamic Fourier formula.

[0048] Example

[0049] Calculation method of carbon brick residual thickness based on single-point furnace brick lining temperature measurement:

[0050] Calculation conditions: single-point thermocouple temperature in carbon brick T1 = 732°C, thermocouple insertion depth in carbon brick L1 = 120 mm, heat flux intensity of furnace cooling wall at corresponding position q = 42.97 kw / m 2 The carbon brick is SGL9RND ultra-microporous carbon brick. The thermal conductivity of this carbon brick at different temperatures is experimentally determined as shown in Table 1:

[0051] Table 1

[0052] Temperature, °C 200 400 600 800 1000 Thermal conductivity, w / (m·K) 23.9 23.3 22.5 20.5 17.8

[0053] 1) Select the thermal conductivity of 20.5w / (m·℃) when the carbon brick embrittlement and alkali metal chemical corrosion start temperature is 800℃, and calculate according to formula (2), T 2初 =T 1初 +q*(L 估 -L 1初 ) / λ 测 , estimate the hot surface temperature T2 of carbon bricks corresponding to different carbon brick residual thicknesses. The results are shown in Table 2:

[0054] Table 2

[0055] L, mm 100 200 300 400 500 600 <![CDATA[T2,℃]]> 690.1 899.7 1109.3 1318.9 1528.5 1738.1

[0056] 2) Since the hot surface temperature of conventional carbon bricks is between 800 and 1550°C, it can be preliminarily determined from Table 2 that the residual thickness of the carbon bricks is between 200 and 500 mm.

[0057] 3) The hot surface temperature of the carbon brick is accurately calculated according to the different thermal conductivity coefficients of the carbon bricks at 600°C, 800°C and 1000°C, using equations (4) and (5). See Tables 3 to 5.

[0058] (1) The thermal conductivity of carbon bricks at 600℃ is 22.5w / (m·℃), and the hot surface temperature T of carbon bricks is calculated. 21 , see Table 3.

[0059] Table 3

[0060] L, mm 200 300 400 450 500 <![CDATA[T 21 ,℃]]> 884.8 1075.8 1266.7 1362.2 1457.7

[0061] (2) The thermal conductivity of the carbon brick at 800℃ is 20.5w / (m·℃), and the hot surface temperature of the carbon brick T is calculated. 22 , see Table 4.

[0062] Table 4

[0063] L, mm 200 300 400 450 500 <![CDATA[T 22 ,℃]]> 899.7 1109.3 1318.9 1423.7 1528.5

[0064] (3) The thermal conductivity of carbon bricks at 1000℃ is 17.8w / (m·℃), and the hot surface temperature of carbon bricks T is calculated. 23 , see Table 5.

[0065] Table 5

[0066] L, mm 200 300 400 450 500 <![CDATA[T 23 ,℃]]> 925.1 1166.5 1407.9 1528.6 1649.3

[0067] 4) When the hot surface temperature of the carbon brick calculated from step 3) is 800°C, the temperature at which embrittlement and alkali metal chemical corrosion begin, the residual thickness of the carbon brick is 200mm; when the hot surface temperature of the carbon brick estimated from step 3) is 1450°C, the temperature at which molten iron begins to flow freely, the residual thickness of the carbon brick is 450mm. Confirm that the residual thickness of the carbon brick ranges from 200 to 450mm, and calculate the thermal conductivity of the carbon brick at different temperatures accordingly, and take the average value, see Table 6.

[0068] Table 6

[0069]

[0070] 5) Using the average thermal conductivity of the carbon bricks obtained in step 4), the residual thickness of the carbon bricks was finally calculated, see Table 7.

[0071] Table 7

[0072] <![CDATA[L1,mm]]> <![CDATA[T 21 ]]> <![CDATA[T 22 ]]> <![CDATA[T 23 ]]> λ, w / (m·℃) L, mm 200 884.8 899.7 925.1 19.3 311 300 1075.8 1109.3 1166.5 19.1 315 400 1266.7 1318.9 1407.9 18.4 322 450 1362.2 1423.7 1528.6 18.1 329

[0073] Taking the average value, the residual thickness of the carbon brick is (311+315+322+329) / 4=319mm.

[0074] The present invention can calculate the residual thickness of carbon bricks when only one normal couple is left at the same position of the blast furnace hearth brick lining. The residual thickness of carbon bricks obtained by the method of the present invention guides the blast furnace operator to take effective furnace protection measures in time to avoid the blast furnace hearth burning through and prolong the life of the blast furnace.

Claims

1. A method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement, characterized in that: The steps include: S1: Based on the thermal conductivity of the furnace carbon brick design and the corresponding thermal conductivity under different temperature conditions measured in the laboratory, the thermal conductivity of the carbon brick at a certain temperature is first assumed, and the single-point couple temperature of the carbon brick is substituted by the thermodynamic Fourier formula to estimate the hot surface temperature of the carbon brick under different residual thicknesses of the carbon brick; S2: Based on the hot surface temperature of carbon bricks at different residual thicknesses estimated by S1 and the empirical value of hot surface temperature of carbon bricks in the blast furnace hearth, the range of residual thickness of carbon bricks is preliminarily determined; S3: Calculate the hot surface temperature of carbon bricks under different residual thicknesses again according to the corresponding thermal conductivity under different temperature conditions measured in the laboratory; S4: according to the calculation result of S3, the range of residual thickness of carbon bricks is determined again. Within this range of residual thickness of carbon bricks, the thermal conductivity corresponding to different residual thickness of carbon bricks at the hot surface temperature of carbon bricks under different residual thickness of carbon bricks described in S3 is calculated, and the average value of thermal conductivity is taken; S5: Using the average value of thermal conductivity obtained in S4, the residual thickness of the carbon brick is finally calculated.

2. According to claim 1, a method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement is characterized in that: The residual thickness of carbon bricks in S1 increases in units of 100 mm. The empirical value of the hot surface temperature of carbon bricks in the blast furnace hearth described in S2 is 800-1550°C. The hot surface temperature range of carbon bricks under different residual thicknesses of carbon bricks estimated in S1 is greater than 800-1550°C, otherwise the range of the residual thickness of carbon bricks is expanded.

3. The method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement according to claim 1 is characterized in that: The thermodynamic Fourier formula is: L=L1+L2=L1+(T2-T1)* λ / q (1) In formula (1), L is the residual thickness of carbon brick, m; T1 is the internal temperature of carbon brick, °C; T2 is the hot surface temperature of carbon brick, °C; L1 is the distance between the internal temperature measuring point of carbon brick and the cold surface of carbon brick, m; L2 is the distance between the internal temperature measuring point of carbon brick and the hot surface of carbon brick, m; λ is the thermal conductivity of carbon brick, w / (m·℃); q is the heat flux intensity of furnace cooling wall, kw / m 2 .

4. The method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement according to claim 1 is characterized in that: S1 estimates the hot surface temperature T of carbon bricks at different residual thicknesses 2初 : T 2初 = T 1初 +q*(L 估 -L 1初 ) / λ 测 (2) In formula (2): 测 is the measured value of thermal conductivity of carbon brick, w / (m·℃); L 1初 is the initial design value of the distance between the thermocouple temperature measuring point inside the carbon brick and the cold surface of the carbon brick, m; T 2初 is the estimated range of carbon brick hot surface temperature, ℃; T 1初 is the internal design temperature of the carbon brick, ℃; L 估 is the estimated residual thickness of carbon bricks, m; the calculation formula of the heat flux intensity q of the furnace cooling wall is: In formula (3), w1 is the furnace cooling wall water pipe flow rate corresponding to the location of the thermocouple temperature measurement point inside the carbon brick, m 3 / h, which can be obtained by reading the flow meter installed on the furnace cooling wall water pipe; t1 and t2 are the actual measured temperature values ​​of the thermometers installed at the inlet and outlet of the furnace cooling wall water pipe, ℃; d is the outer diameter of the furnace cooling wall water pipe, m; h is the length of the furnace cooling wall water pipe, m.

5. The method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement according to claim 1 is characterized in that: In S2, the empirical value range of the hot surface temperature of carbon bricks in the blast furnace hearth is taken from the carbon brick hot surface temperature range value estimated in S1, and the carbon brick residual thickness range corresponding to the empirical value range of the hot surface temperature of carbon bricks in the blast furnace hearth is preliminarily determined in the carbon brick residual thickness range estimated in S1.

6. The method for calculating the residual thickness of carbon bricks based on single-point furnace brick lining temperature measurement according to claim 1 is characterized in that: Calculation of hot surface temperature of carbon bricks at different residual thickness of carbon bricks as described in S3: In formula (4): q is the heat flux intensity of the furnace cooling wall, kw / m 2 ; λ i T 1i Thermal conductivity of carbon brick at temperature, w / (m.℃); T1 is the internal couple temperature of carbon brick, ℃; T 2i is the hot surface temperature of carbon brick under different residual thickness of carbon brick, ℃; L is the residual thickness of carbon brick, m; L1 is the distance between the thermocouple temperature measuring point inside the carbon brick and the cold surface of the carbon brick, m.

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