JP2746004B2 - Estimation method of bottom erosion line of blast furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a bottom erosion line of a blast furnace.

[0002]

2. Description of the Related Art At present, the life of a blast furnace such as a blast furnace is as follows.
It is no exaggeration to say that it is determined by the life of the hearth.
Further, if the furnace bottom wear progresses and a hole is formed in the furnace bottom, a large amount of melt in the furnace flows out of the furnace, which may lead to a major disaster. In order to prevent such a situation from occurring, it is extremely important to estimate the refractory bottom erosion line as accurately as possible.

FIG. 4 is a flowchart showing the contents of a conventional method of estimating a bottom erosion line proposed in Japanese Patent Application Laid-Open No. 60-184606, and FIG. 5 schematically shows an initial state of a blast furnace bottom. FIG. As shown in FIGS. 4 and 5, in order to estimate the hearth erosion line 5, first, the furnace bottom (refractory 1, refractory 2, and refractory 3) is divided into elements and then the finite element method (FEM) or After modeling the furnace bottom using the boundary element method (BEM), the boundary conditions are given and the heat transfer analysis is performed.
Compare the calculated temperature of the installation position of the device with the measured temperature. When the difference between the two is greater than a certain value tc, the element division initially set to change the estimated erosion line 5 is changed and the heat transfer analysis is performed again, and the difference becomes equal to or less than the certain value tc. Check whether or not. Such processing is repeatedly performed until the deviation becomes equal to or less than a certain value tc, and the erosion line of the analysis model when the deviation becomes equal to or less than a certain value tc is set as an estimated line. In addition,
In this specification, in FIGS. 8 and 10 to 13 described later, reference numerals 1 to 3 indicate refractories, and reference numeral 4
Denotes a temperature sensor, and reference numeral 5 or 5 'denotes an erosion line, respectively.

FIG. 6 is an explanatory diagram showing an example in which a furnace bottom erosion line is axially symmetrically modeled by dividing the element by the finite element method when the furnace bottom refractory is not worn (initial state). FIG. 8 is an explanatory view showing an example in which the hearth erosion line is axisymmetrically modeled by the boundary element method when there is no wear of the hearth refractory.

In the case of the finite element method shown in FIG. 6, the furnace bottom is divided by a number of elements, and a temperature sensor 4 is provided at some of the vertices (nodes) (circled parts) of each element. ing. On the other hand, in the case of the boundary element method shown in FIG. 8, each element is expressed as a line segment, and both end points of each element are nodes.

[0006] In the finite element method shown in FIG. 6 or the boundary element method shown in FIG.
Both Boundary A: Furnace bottom cooling condition Boundary: Side wall cooling condition Boundary C: Insulation or similar conditions Boundary D: Constant temperature condition (for example, 1150 which is the melting point of pig iron
° C) and boundary D is the erosion line.

[0007]

FIG. 7 is an explanatory diagram showing the state of element division by the finite element method when the erosion line 5 'changes from the initial state shown in FIG. 6 due to the progress of wear of the refractory. 6 and FIG.
As can be understood from the comparison, the element division is changed and the number of elements is changed from the case of the initial state shown in FIG. If the element division is not changed, the change in the heat transfer state due to the wear of the refractory cannot be accurately calculated, and the analysis accuracy is significantly reduced.

[0008] To change such element division, an analyst with specialized knowledge is required. By the way, in recent years, the calculation itself of the heat transfer analysis by the finite element method or the boundary element method has been increased in speed and cost with the development of computers. Therefore, when estimating the erosion line at the furnace bottom, the time and labor occupied by the correction work of the element division have been increasing.

Specifically, consider the case where the erosion line changes due to the progress of wear of the refractory. FIG. 9 shows that the amount of wear of the refractory is relatively small in the boundary element method (erosion line:
5 ') is an explanatory diagram showing a case where no geometrical phase change in element division occurs in the wear portion due to 5'). In the case shown in FIG. 9, the modification of the element division can be performed only by changing the coordinates of some of the nodes (a to c in the figure), so that it is very easy.

However, as shown in FIG. 11, FIG. 12, or FIG. 13, for example, due to the partial remarkable wear of the refractory and the new generation of a solidified layer, the wear portion has a geometrical shape based on element division. When a large phase change occurs, the element division in the initial state must be changed. Therefore, an analyst is required, and a great deal of time and labor is required.

FIG. 10 is an explanatory diagram showing a case in which the amount of wear of the entire refractory is not so large, but significant wear occurs partially in the wear portion, resulting in a geometrical phase change in the boundary element method. In the example shown in the figure, there is a concave area caused by wear in a part of the analysis area, but in general in the boundary element method, if a concave area occurs in the element area (the area surrounded by line elements), the analysis accuracy Is known to decrease. Therefore, usually, as shown in FIG. 11, a new line element 6 is added near the concave area to divide the concave area into two convex areas. A skilled analyst is required to confirm whether or not such a concave area is generated and to add a line element.

FIG. 12 shows a case where the wear of the refractory further progresses and the erosion line 5 'is remarkably changed, and a geometric phase change occurs in the wear portion. In this case, when compared with the initial element division shown in FIG. 8, the geometric phase has changed so much that the element division has to be newly set as a whole, requiring a skilled analyst. And

On the other hand, FIG. 13 shows a case where the melt at the bottom of the furnace is partially solidified and a solidified layer 7 is formed at the worn portion. In this case, the solidified layer 7 needs to be divided into elements as a part of the furnace wall. However, since the solidified layer 7 has a different thermal conductivity from the refractory 3, a new element region needs to be added. This case also requires an analyst.

Although such an analysis is an operation to be performed on a daily basis, the conventional method involves a complicated operation of correcting the element division for the analysis when the erosion line changes. Requires an engineer (analyzer) with specialized knowledge, and has spent a great deal of labor and time.

As described above, whether the finite element method or the boundary element method is used, an erosion line is estimated by an analyst, and even the analyst requires a great deal of correction to correct the element division. He spent his time and effort. Here, an object of the present invention is to simplify and simplify the modification work of element division, greatly reduce the dependence on an analyst in estimating an erosion line, and further facilitate complete automation. It is an object of the present invention to provide a method for estimating a bottom erosion line of a blast furnace.

[0016]

Here SUMMARY OF THE INVENTION, it is an aspect of the present invention, by using the finite element method based on the measured temperature by a plurality of temperature sensors installed in the furnace bottom of a blast furnace analysis
A method of estimating the erosion line of the furnace bottom refractory by a finite element model of the region obtained by element division, said analysis territory
While expanding the range up to the melt region, without the element division is changed, characterized by changing the erosion lines in the finite element model by changing the thermal conductivity of each element in the finite element model This is a method for estimating the bottom erosion line of the blast furnace.

In other words, the present invention provides a finite element simulation (based on the temperature at the temperature sensor position while changing the erosion line in the finite element model) based on the measured temperatures of a plurality of temperature sensors installed at the bottom of the blast furnace. In the method of estimating the erosion line of the furnace bottom refractory of the blast furnace by changing the measured temperature and the calculated temperature until the difference between the measured temperature and the calculated temperature is equal to or less than a certain allowable value, the element division initially set is changed. This is a method for estimating a bottom erosion line of a blast furnace, wherein the thermal conductivity of each element is changed without changing the element division when necessary.

The configuration of the present invention will be described with reference to FIGS. FIGS. 1 and 2 are explanatory views showing examples of element division in the present invention. FIG. 1 shows an initial state, and FIG. 2 shows a state in which wear of refractories has progressed and the erosion line has changed significantly. .

(1) First, the entire region to be analyzed is divided into elements by the finite element method. Although elements divided by the finite element method is the same as the conventional method, the present invention, as shown in FIG. 1, the analysis region than conventional solvent
The entire area to be analyzed is such that it is sufficiently expanded to the hot water area, and the extent to which the solidified layer does not protrude from the analysis area even when the solidified layer is formed. For example, in the case of a blast furnace, the level is set from the bottom plate to the tap hole level or a level slightly higher (about 1000 mm).

(2) Appropriate cooling boundary conditions are applied to the boundary A (furnace bottom) and the boundary B (sidewall). The boundary condition of each of the boundary A and the boundary B may be the same as that for estimating the hearth erosion line by the conventional finite element method.

(3) As for the boundary C, adiabatic or a boundary condition close thereto is given. The boundary condition of the boundary C may be the same as that for estimating the hearth erosion line by the conventional finite element method.

(4) A constant temperature condition is given for the boundary D '. The boundary condition of the boundary D ′ may be the same as the boundary condition (for example, the melting point of pig iron: 1150 ° C.) given to the erosion line at the time of estimating the conventional furnace bottom erosion line.

(5) Higher temperature side than erosion line 5 (boundary D 'side)
Each of the elements 8 (elements in the area where the dot pattern is formed in FIGS. 1 and 2) has a very large thermal conductivity of, for example, about 10 to 1000 times that of steel, and the other elements are made of the corresponding material. Gives thermal conductivity.

(6) When the heat transfer analysis is performed using the finite element method under such conditions, each element 8 having a large thermal conductivity is obtained.
Of the erosion line 5 (or
5 ') The upper temperature is almost the same as the boundary D'. Therefore, the analysis result is almost the same as the conventional analysis in which the condition of the boundary D 'is provided on the erosion line 5 (or 5').

(7) When the erosion line changes and it is necessary to change the initially set element division, for example, when the refractory wear is advanced, the thermal conductivity of the element in that part is changed to the original physical property. Change to a very large value instead of the value. By making such a change, the wear can be easily expressed analytically. When a solidified layer is formed, the thermal conductivity of the element in the portion where the solidified layer is formed may be given the physical property value of the solidified layer itself instead of a very large value, and there is no need to change the element division.

FIG. 2 is an explanatory view showing an example of element division when the wear of the refractory has progressed.
This is exactly the same as the condition shown in FIG. As described above, according to the present invention, in the finite element method, even when the erosion line greatly changes due to, for example, remarkable wear of the refractory, the physical property values of each element (heat conduction The erosion line can be changed simply by changing the rate. In the present invention, "estimation"
Means finding a convergent solution by the finite element method as in the conventional method.

[0027]

In the estimation of the bottom erosion line by the finite element method or the boundary element method which has been conventionally used, only the refractory and the solidified layer at the bottom are divided into elements as an analysis region, and the boundary condition is defined on the outside of the furnace as a boundary condition. Appropriate cooling conditions are applied to the inside of the furnace (that is, the erosion line) at a constant temperature (for example, the melting point of pig iron is 1150 ° C), heat transfer analysis is performed, and the calculated temperature is compared with the measured temperature to determine the erosion line on the model. Was corrected, and the same analysis was performed again. The erosion line was estimated as a convergence solution when the deviation between the calculated temperature and the measured temperature became equal to or less than a predetermined value tc.

However, in such a conventional method of estimating the erosion line, the analysis area changes when the erosion line changes due to wear of the refractory or a new solidified layer is formed. In the method and the boundary element method, it is necessary to change the element division according to these changes. Since the modification of the element division requires a high level of specialized knowledge, an analyst who requires specialized knowledge is required.

On the other hand, in the present invention, a finite element method is used as an analysis method as in the conventional method. After dividing the elements in advance and giving the thermal conductivity of all elements on the higher temperature side than the erosion line as very large values, apply the constant temperature condition to the furnace inner boundary of the entire analysis area as in the conventional method . By giving the element division and the boundary condition in this way, the heat transfer resistance of the element between the boundary D ′ and the erosion line 5 in FIG. In the erosion line, the same result as when the aforementioned constant temperature condition is given can be obtained.

Here, referring to FIG.
The specific operation procedure of the method for estimating the erosion line
And will be further described. That is, in FIG.
Estimation of the food line 5 'is based on the previous estimation line 5 (the first
In this case, heat conduction analysis was conducted using the
The theoretical temperature at the position of the thermometer 4 embedded in the brick
To calculate the T _1. Then the actual temperature _{T 2} and _{T 1} of the thermometer 4
Compare. The previous estimation line is the same as the current erosion line
If they are the same, T ₁ = T ₂ should be satisfied . (In reality |
T ₁ -T ₂ | if ≦ _{t c T} 1 = _{T 2} and regarded) where
In, if when the measured temperature T ₂ is greater than T ₁ is the brick
This is because erosion progressed and the erosion line moved outside the furnace.
Therefore, the erosion line 5 is moved to the outside of the furnace. New
The above procedure is based on the estimated erosion line as the previous estimation line.
repeat. The erosion line when T ₁ = T ₂ is now
This is the estimated erosion line. That is, in FIG.
For the finite element in the area (A), the inside of the furnace of the erosion line
(High temperature side)
Changed to extremely large thermal conductivity of about 1000 times
On the other hand, for the finite element in the area (B),
Very large steel thermal conductivity from brick thermal conductivity (brick
Is changed to the thermal conductivity of the solidified layer).
Actually, a plurality of thermometers (4-a, 4-b, 4-c ...
Perform the above procedure for ()). For example, FIG.
As shown in the figure, the erosion line 5 is
Division (Erosion line part 5-a corresponds to thermometer 4-a)
And if T ₂ > T ₁ for thermometer 4-a , part 5
-A is moved outside the furnace. For thermometer 4-Ha _{T 2}
<T ₁ if part 5-C of the erosion line movement of the to the furnace inside
Let Smoothly connected the moved erosion line
The thing is a new erosion line 5 '. New erosion line
The heat conduction analysis is performed again using 5 ′. Repeat the above procedure
Ri returns, when it becomes _T 2 = _{T 1} for all of the thermometer
Is the current estimated erosion line. The present invention
In the case of, by changing the property value of the finite element method,
It has the same meaning as changing the food line. If the erosion line changes as refractory wear progresses,
The thermal conductivity of the corresponding element may be given as a very large value instead of the original physical property value (thermal conductivity). May be given the physical property value of the solidified layer itself. The erosion line can be easily and quickly changed only by changing the physical property value of the element corresponding to the portion where the change has occurred.

As described above, according to the present invention, it is possible to obviate the need for the analyst to perform geometrical modification of element division, which is required by the conventional estimation method because of the complicated procedure. This also allows for full automation of erosion line estimation.

In the present invention, since the erosion line is formed by connecting predetermined element dividing lines, the eroded portion may not be smooth depending on the state of erosion and the size of the element. However, this can be alleviated to a level that does not pose any problem in practice by making the element division sufficiently fine. Further, the present invention will be described in detail with reference to examples, but this is an exemplification of the present invention, and the present invention is not limited thereto.

[0033]

EXAMPLE The present invention was applied when estimating a low erosion line of an existing large blast furnace shown in FIG. 3 (b) . That is, the entire region to be analyzed is divided into elements by the finite element method so that the solidified layer can completely include the solidified layer even if it is formed on the furnace bottom. In the present invention , a two-dimensional axisymmetric body is divided by the finite element method in a range from the furnace bottom plate to a level slightly higher (about 1000 mm) than the tap hole level.

As described above, the boundary conditions were given for the boundary A (furnace bottom), the boundary B (sidewall), the boundary C, and the boundary D '. The boundary conditions for the boundaries A, B, and C were the same as those used for estimating the hearth erosion line by the conventional finite element method, and the boundary D 'was a constant temperature condition.
The boundary condition of the boundary D ′ was the same as the boundary condition that had been applied to the erosion line when the conventional furnace bottom erosion line was estimated (melting point of pig iron: 1150 ° C.).

Each element 8 on the high temperature side (upper side) of the erosion line (element in the area where the dot pattern is given in FIGS. 1 and 2)
Gives a very large thermal conductivity: 40,000 W / mK, and for other elements, the thermal conductivity of the corresponding material, refractory 1: 30.0 W / mK, refractory 2: 16.3 W / mK, refractory 3: 1.
7 W / mK, solidified layer: given as 14.0 W / mK.

When a heat transfer analysis is performed using the finite element method under such conditions, the heat transfer resistance of each element 8 having a large thermal conductivity becomes extremely small, and the erosion line 5 (or 5 ')
The upper temperature was almost the same as the boundary D '. Therefore, the analysis result was almost the same as the conventional analysis method in which the condition of the boundary D ′ was provided on the erosion line 5 (or 5 ′).

In order to change the erosion line, for example, when wear of the refractory progresses and erosion of the refractory becomes remarkable, the thermal conductivity of the element of the eroded portion is replaced with the above-mentioned original physical property value, Was changed to a large value (40000W / mK). By making such a change, the erosion line can be easily estimated without newly performing element division.

[0038]

As described in detail above, according to the present invention,
Only by changing the thermal conductivity of each element in the finite element method, a change in the erosion line and the generation of a solidified layer can be expressed using a model without redoing the element division. Therefore, the erosion line can be easily changed. Therefore, in estimating the erosion line, the labor and time of the analyst can be reduced or omitted.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of element division in the present invention, showing an initial state.

FIG. 2 is an explanatory diagram showing an example of element division in the present invention, showing a state in which wear of a refractory has progressed and an erosion line has changed significantly.

FIGS. 3A and 3B are explanatory diagrams showing the results of the examples.

FIG. 4 is a flowchart showing the contents of a conventional method of estimating a furnace bottom erosion line proposed in Japanese Patent Laid-Open No. 60-184606.

FIG. 5 is an explanatory view schematically showing an initial state of a blast furnace bottom.

FIG. 6 is an explanatory diagram showing an example in which a furnace bottom erosion line is axisymmetrically modeled by dividing elements by a finite element method when wear of a furnace bottom refractory has not occurred (initial state).

FIG. 7: Erosion line 5 'due to progress of refractory wear
FIG. 7 is an explanatory diagram showing a state of element division in the finite element method when the state changes from the initial state shown in FIG. 6.

FIG. 8 is an explanatory diagram showing an example in which a hearth erosion line is axisymmetrically modeled by the boundary element method when there is no wear of the hearth refractory.

FIG. 9 is an explanatory view showing a case in which a geometric phase change does not occur in a worn portion due to a relatively small amount of wear of a refractory (erosion line: 5 ′) in the boundary element method.

FIG. 10 is an explanatory diagram showing a case where a concave region occurs in an analysis region due to a large amount of wear of a refractory in the boundary element method.

FIG. 11 is an explanatory diagram showing an example in which a new element 6 is added to a concave area to divide the concave area into two convex areas.

FIG. 12: The wear of the refractory further progresses and the erosion line 5 ′
FIG. 4 is an explanatory diagram showing a case where changes have occurred and a geometrical phase change has occurred in a wear portion.

FIG. 13 is an explanatory diagram showing a case where a melt at a furnace bottom partially solidifies and a solidified layer is generated in a worn portion.

[Explanation of symbols]

 1-3: refractory 4: temperature sensor 5, 5 ': erosion line 6: new element 7: solidified layer 8: element

Claims (1)

(57) [Claims] 1. An analysis using a finite element method based on measured temperatures obtained by a plurality of temperature sensors installed at a furnace bottom of a blast furnace.
A method of estimating the erosion line of the furnace bottom refractory by a finite element model of the region obtained by element division, said analysis territory
While expanding the range up to the melt region, without the element division is changed, characterized by changing the erosion lines in the finite element model by changing the thermal conductivity of each element in the finite element model Estimation method of bottom erosion line of blast furnace.