JPH09151380A - Method for estimating strength of coke for blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the strength of coke with high accuracy, which is useful for the mixing management of coals to be fed to a coke furnace, by using each value of the maximum fluidity and an average reflectivity of each single coal, an average of these values and the degrees of the distributions of the physical properties of mixed coal as parameters. SOLUTION: In order to estimate the strength of coke which is used for the mixing management of coals to be fed to a coke furnace, following values are used as parameters. Each value of the maximum fluidity (MFi ) and an average reflectivity (Romi ) of each single coal (i). Weighted mean values (MFB) and (Rom B) of the maximum fluidity and average mean values of mixed coal in terms of a compounding ratio (fi ) of each single coal (i). Besides these, following values expressing the distributions of the physical properties of the mixed coal: a value expressed by equation I [(v) is a variance; xi is a physical property of a single coal (i) (e.g. Romi ); N=Σfi ; Xav =(1/N)Σfi xi (e.g. Romi ); σ is a standard deviation], a value expressed by equation II [γ1 is a skewness; μ3 =(1/N)Σfi (xi - xav )<3> ] and a value expressed by equation III [γ2 is a kurtosis; μ4 =(1/N)Σfi (xi - xav )<4> ].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blending method of blended coal which is indispensable for designing the strength of coke, and has an object of improving the accuracy of estimating the strength of coke.

[0002]

2. Description of the Related Art In order to estimate the coke strength, generally, an index due to the carbonization degree of coal and an index due to the fluidity are used. For example, in Japanese Patent Application Laid-Open No. 2-20592,
In order to improve the estimation accuracy of the flowability of blended coal, the logarithmic value of each flowability at each constant temperature between the flow start temperature and the solidification temperature of each raw coal is calculated, and the flow of the blended coal is calculated from the weighted average value A method has been proposed in which the maximum value of the fluidity of the coal blend obtained is estimated as the maximum fluidity (MF) of the coal blend and the coke strength is estimated.

Further, an estimation formula of coke strength using the weighted average value of the maximum fluidity of each coking coal, the weighted average value of the solidification temperature, and the variation of the solidification temperature has been proposed (Japanese Patent Publication No. 2-14398). ). However, even with the above-mentioned conventional technique, the present situation is that the estimation accuracy of the coke strength is still insufficient.

That is, the conventional coke strength estimation method has been studied for the case where the mixing ratio of coking coal is relatively high, but in order to reduce the production cost of the coke, the non-liquid coke having a low fluidity is used. Caking coal and slightly coking coal (hereinafter, abbreviated as non-coking coal) have been added more and more, and fluctuations in coke strength that cannot be predicted by conventional estimation methods have become apparent.

Such fluctuations are caused by the fact that the flow temperature range is different between caking coal and non-slightly caking coal, as shown in FIG. It was estimated that the shape of the rate distribution changed.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a technique for accurately estimating fluctuations in coke strength that cannot be predicted by the conventional method.

[0007]

The present invention is directed to coke oven equipment.
How to Estimate Coke Strength Used for Coaling Mixing Control
, The maximum fluidity of each plain coal i (MF_i) And average reflection
Rate (R_0mi) And the blended coal which is the weighted average value of the blending ratio
Maximum fluidity (MF_B) And average reflectance (R _{0 mB})
In addition, the following equations (1), (2) expressing the distribution of physical properties of blended coal
And the variance, skewness, and kurtosis defined in (3).
Estimation of coke strength characterized by being used as data
Is the way.

Dispersion: v (x) = (1 / N) Σf_i(x_i− X_av)^Two= {Σ (x)}^Two(1) Distortion: γ₁(x) = μ_Three/ {Σ (x)}^Three・ ・ ・ ・ ・ (2) Kurtosis: γ_Two(x) ＝ [μ_Four/ {Σ (x)}^Four] -3 ... (3) where μ_r= (1 / N) Σf_i(x_i− X_av)^r, N = Σf
_i, X_av= (1 / N) Σf _ix_i, F_i: Blending ratio of i coal type,
x_i: I Indicates the physical property value of coal species.

Further, in the present invention, the above-mentioned x_iWhen
Then, the average reflectance (R _0mi), X_av
As above (R_0mi) And blending ratio f_iIs the weighted average of
Average reflectance of blended coal (R_{0 mB}) Is preferred
No.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present invention, in order to solve the above problems, in order to reflect the overlapping of the flow temperature of each plain coal of blended coal in the estimation formula of the coke strength, the distribution of physical property values of coal such as average reflectance of coal is newly added. The skewness and kurtosis, which are indices of the shape, are introduced into the strength estimation formula to improve the estimation accuracy.

The average reflectance (R _0mi ) of non-caking coal depends on the type of non-caking coal and the average reflectance (R _0mi ) of caking coal.
There is a lower one and a higher one (Fig. 3), and the distribution profile of the average reflectance of the blended coal is shown in Fig. 2 as the addition of the non-caking coal increases.
As in (a) and (b), the shape is flat or the distribution peaks are skewed to the left and right. For this reason, the overlapping conditions of the flow temperatures of the individual coals in the blended coal change, the coal particle fusion conditions such as the width of the flow temperature region and the occurrence of expansion pressure change, and the coke strength of the blended coal changes. It is thought that.

In the present invention, the physical property values (x
_i), The variance of the distribution v (x), the distortion that represents the deviation from the normal distribution
Degree γ₁(x), kurtosis γ_Two(x) is used in the strength estimation formula. Skewness γ
₁(x), kurtosis γ_Two(x) is expressed by the following equations (2) and (3), and
The distribution shape should be expressed as shown in (a), (b), (c), and (d).
Can be. Variance: v (x) = (1 / N) Σf_i(x_i− X_av)^Two= {Σ (x)}^Two(1) Distortion: γ₁(x) = μ_Three/ {Σ (x)}^Three・ ・ ・ ・ ・ (2) Kurtosis: γ_Two(x) ＝ [μ_Four/ {Σ (x)}^Four] -3 ... (3) where μ_r= (1 / N) Σf_i(x_i− X_av)^r, N = Σf
_i, X_av= (1 / N) Σf _ix_i, F_i: Blending ratio of i coal type,
x_i: I Indicates the physical property value of coal species.

(Note that γ ₁ (x) and γ ₂ (x) in the case of normal distribution
= 0. ) As the physical property value x _i of each brand coal (each plain coal), for example, the average reflectance (R _0mi ) of each plain coal i is used, and as x _av , the (R _0mi ) and the blending ratio f _{i are used.} It is preferable to use the average reflectance (R _0mB ) of the blended coal, which is the weighted average value of
Since the average reflectance of coal has a correlation with the solidification temperature, the variance, skewness, and kurtosis of the average reflectance of blended coal are indicators of the distribution of the solidification temperature.

In the method disclosed in the above Japanese Patent Publication No. 2-14398, the correction is made in consideration of the dispersion of the solidification temperature. However, as the distribution deviates from the normal distribution, the correction accuracy decreases and the strength is estimated. The accuracy decreases. On the other hand, in the estimation method of the present invention, since the distribution shape is also taken into consideration, it is preferably applied as non-slightly caking coal is increased and the variation in the quality of the mixed coal increases.

Although the distribution of the average reflectance in the blended coal has been described above, the variance, the skewness and the kurtosis (hereinafter referred to as the distribution) representing the distribution of the maximum fluidity in the blended coal should be used for estimating the coke strength. Is also preferable. Further, the distribution of the solidification temperature, the distribution of the maximum flow temperature, the distribution of the flow start temperature, and the distribution of the physical property values correlated with these may be used in the coal blend.

Further, it is also preferable to use the distribution of the above-mentioned physical properties such as the distribution of the average reflectance, the distribution of the maximum fluidity and the distribution of the solidification temperature together to estimate the coke strength. In the present invention, as shown in the examples below, the maximum fluidity (MF _B ) and the average reflectance (R
_0mB ), in addition to the above formula expressing the distribution of physical properties of blended coal
Variance defined by (1), (2) and (3): v (x), skewness: γ ₁ (x), and kurtosis: γ ₂ (x) are parameters, and strength is a dependent variable. The coke strength can be predicted by presetting the following equation (4).

Strength = f (MF _B , R _0mB , v (x), γ ₁ (x), γ ₂ (x)) ··· (4) That is, in advance of the above parameters for various blended coals The value is obtained, and the constant (coefficient) in the above equation (4) is obtained by statistical analysis such as multiple regression analysis from the measured values of coke strength obtained from those various blended coals, and the obtained regression equation is used. It is possible to predict the coke strength of the required coal blend.

It is possible to use a linear function, a quadratic function, a fractional function or the like in the above formula (4), and the linear function shown in the embodiment described later is preferable, but it is not particularly limited to the functional form. Absent.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. The five types of blended coal shown in Table 1 were dry-distilled under the dry-distillation conditions shown in Table 2 in a chamber furnace type test furnace (electric furnace) having a coal loading of 40 kg to obtain agglomerated coke. The coke strength was measured by the tumbler strength test method (JIS K2151).

That is, after the lump coke was loaded into the tumbler tester and rotated 400 times, the tumbler strength TI ₆ ⁴⁰⁰ , which is the yield (%) of +6 mm, was measured, and the estimation obtained by the estimation method of the present invention. The relationship with the value was investigated. The tumbler strength TI ₆ ⁴⁰⁰ is an index showing the abrasion resistance of coke. With the measurement result of the tumbler strength of the obtained coke,
Table 3 shows the physical property values shown in Table 1 and the estimated values based on the intensity estimation formulas separately obtained from the statistical analysis (multiple regression analysis) in advance.

The strength estimation formula is as follows:
The average reflectance is used as [A], and the average reflectance variance: v
(R_0m), Skewness: γ₁(R_0m), Kurtosis: γ_Two(R_0m) Consider
The following formula (5) [Example of the present invention], and [B] of the average reflectance
Variance: v (R_0m(6) (Comparative example)
Was used. TI₆ ⁴⁰⁰= A + b × MF_B+ C × R_{0 mB}+ D × v (R_0m) + E × γ₁(R_0m) + F × γ_Two(R_0m) ・ ・ ・ (5) TI₆ ⁴⁰⁰= A '+ b' x MF_B+ C '× R_{0 mB}+ D '× v (R_0m) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (6) Where MF_B: Maximum fluidity of blended coal (blending ratio of plain coal
Weighted average value), R_{0 mB}: Average reflectance of blended coal
(Weighted average value based on blending ratio of plain coal), v (R _0m):
Variance of average reflectance distribution of blended coal, γ₁(R_0m): Blended coal
Skewness of the average reflectance distribution of, γ_Two(R_0m): Average of blended coal
Kurtosis of reflectance distribution, a, b, c, d, e, f, a ',
b ', c', d ': regression coefficients (constants) are shown.

From Table 3, the skewness γ ₁ (R _0m ) and the kurtosis γ
_In the blended coal C in which ₂ (R _0m ) is an almost intermediate value of each blended coal, the measured value and the estimated value of the tumbler strength are the same in the comparative example and the example of the present invention, but the skewness γ ₁ (R _0m ) It can be seen that although the comparative example does not correspond to the change in the kurtosis γ ₂ (R _0m ), the invention example corresponds well. From the above results, it was found that it is possible to improve the estimation accuracy of the tumbler strength by introducing the distribution shape of the physical property values of the blended coal obtained from the physical property values of each plain coal of the blended coal.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

EFFECTS OF THE INVENTION According to the present invention, the tumbler strength of coke can be predicted with high accuracy, which not only contributes to the stability of blast furnace operation, but also increases the degree of freedom in the blending of coking coking coal and increases the amount of inferior coal. Blending is possible, and it can contribute to the reduction of coking coal cost.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the skewness and kurtosis of the distribution of average reflectance of blended coal.

FIG. 2 is a graph showing a distribution pattern of average reflectance of blended coal.

FIG. 3 is a graph showing an average reflectance and a flow temperature region of non-slightly caking coal and caking coal.

Claims (2)

[Claims] 1. A coke used for controlling the composition of a coal charged in a coke oven.
Maximum flow for each plain coal i
Degree (MF_i) And average reflectance (R_0mi) Each
Maximum fluidity (MF) of blended coal, which is a weighted average value of_B)
And average reflectance (R_{0 mB}) In addition to the
The distribution defined by the following equations (1), (2) and (3)
It is special to use dispersion, skewness and kurtosis as parameters.
Method for estimating the strength of coke. Dispersion: v (x) = (1 / N) Σf_i(x_i− X_av)^Two= {Σ (x)}^Two(1) Distortion: γ₁(x) = μ_Three/ {Σ (x)}^Three・ ・ ・ ・ ・ (2) Kurtosis: γ_Two(x) ＝ [μ_Four/ {Σ (x)}^Four] -3 ... (3) where μ_r= (1 / N) Σf_i(x_i− X_av)^r, N = Σf
_i, X_av= (1 / N) Σf _ix_i, F_i: Blending ratio of i coal type,
x_i: I Indicates the physical property value of coal species. 2. x_iAs the average reflectance of each plain coal i
(R_0mi), X _avAs above (R_0mi) And blending ratio
f_iAverage reflectance of blended coal (R_{0 mB})
The method for estimating coke strength according to claim 1, wherein