JPH0694367A - Estimating method for depositing shape of material to be chaged in vertical furnace - Google Patents

Abstract

PURPOSE:To contribute to improvement in an accuracy of controlling a distribution of a material to be charged by accurately estimating a depositing shape of the material to be charged at a furnace wall side from a dropping point of the material to be charged when the material is charged in a vertical furnace such as a blast furnace, etc. CONSTITUTION:In a vertical furnace such as a blast furnace, etc., a depositing shape of a material to be charged at a furnace wall part from a dropping point of the material to be charged is presumed as a function of a sum of a Gaussian distribution function and a linear function, coefficients of the function are decided based on previously actually measured data to be estimated.

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 deposit shape of a charge deposited in a vertical furnace such as a blast furnace or when discharged from a hopper.

[0002]

2. Description of the Related Art Conventionally, as a method of estimating the deposit shape of a charge charged by a blast furnace charging apparatus, a deposit shape detecting apparatus (hereinafter referred to as a profile meter) using a microwave type or the like in an actual blast furnace. There is known a method (method A) of actually measuring the deposition shape and creating a regression equation from the measurement result. As a method of theoretically estimating the deposition shape, it is well known that the angle of repose is approximately from the middle of the furnace to the center of the furnace, and that it can be estimated quite accurately by considering the influence of the gas flow velocity. There is. On the other hand, as a method of estimating the deposit shape from the dropping point of the charging material to the furnace wall portion, there is a method using a formula in which the inclination angle from the ridgeline near the dropping point to the furnace wall portion is linearly approximated (B
Method) (for example, Iron and Steel 73 (1987) 1, P91).

[0003]

However, such a conventional estimation method has the following problems. The conventional estimation method A has a good estimation accuracy in the charging method that has been implemented in the past, but the reliability of the estimation accuracy when the charging conditions are largely changed is considerably lowered. Further, in this method, it is difficult to estimate the deposition shape itself in a blast furnace that has no means for detecting the deposition shape.

In the conventional estimation method B, the reliability of the estimation accuracy does not change much even when the charging conditions are largely changed.
In the first place, the estimation accuracy was not necessarily high. The following estimation method was invented in order to solve such a problem and perform estimation with higher accuracy.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problems of the above-mentioned conventional method, and estimates the shape of the deposited charge in the portion closer to the furnace wall from the dropping point from the furnace top hopper. Assuming a summation function of a Gaussian distribution function and a linear function as a deposition shape, the Gaussian distribution function and 1
This is a method for estimating the deposition shape of a charge in a vertical furnace, which is characterized in that the deposition shape is obtained by determining each coefficient of the function of the sum of the following functions.

[0006]

First, when the deposition shape of the furnace wall portion is obtained, one charging is divided into several portions as shown in FIG. 1 and the thick line portion is calculated by the method of the present invention. The deposition shape for each section is calculated by the method described below. FIG. 2 is a schematic diagram of the deposition shape and inclination angle distribution of the furnace wall portion. As in the conventional knowledge, the inclination angle becomes closer to the center of the furnace than the drop point in consideration of the gas flow velocity.

On the other hand, in the part on the furnace wall side from the drop point,
The deposition shape is the Gaussian distribution function (normal distribution function) shown in Equation 1.
It is assumed that the function can be approximated by the function of the sum of the linear function and the linear function.

[Equation 1]

Where A is a coefficient relating to the deposition height B is a coefficient relating to the deposition position C is a coefficient relating to the deposition width D is a coefficient for correcting the influence of the deposition shape of the base E is a coefficient relating to the deposition depth X is a calculation position (origin) Is the center of the furnace, the furnace wall direction is positive)

The tilt angle distribution can be defined by the arctangent of the first derivative of the equation 1, that is, arctan (PF '), and is represented by the equation 2.

[Equation 2]

Here, A, C and D are mainly coefficients relating to the deposition shape, B is a coefficient relating to the deposition position, and these undetermined coefficients are obtained by setting the following three boundary conditions. (1) The arctangent of the slope of PF (X) at the inflection point inside the furnace corresponds to the angle of repose (θ _R ). (2) The arctangent of the inclination of the PF (X) at the inflection point on the furnace wall side corresponds to the maximum inclination (sign is negative) on the furnace wall side, that is, the minimum value (θ _m ) of the inclination angle. (3) The slope of PF (X) at infinity of X becomes a constant value (θ _{M U} ).

If rewritten in the form of the formula, it becomes as follows. PF ″ (X) = 0, X (θ) = θ _R PF ″ (X) = 0, θ (X) = θ _{m When} X is positive infinity, θ (X ) = Θ _{M U}

From the above boundary conditions, A, B, C and D are obtained as follows.

[Equation 3] Or

[Equation 4]

[Equation 5]

[Equation 6]

[Equation 7] Or

[Equation 8]

Where X _R is the point where the inclination angle sharply decreases from the angle of repose (PF
(Inflection point of (X)) X _m ; point at which the inclination angle becomes minimum (inflection point of PF (X)) θ _R ; repose angle (inclination angle at X _R ) θ _m ; minimum value of inclination angle ( Tilt angle at X _m ) θ _{M U} ; Tilt angles at infinity X _R , X _m , θ _R , and θ _m vary depending on the charging method, charging, etc. It is obtained by measuring basic data in measurement, and therefore A, B,
C and D can be estimated. Table 1 shows measurement examples of A, C and D in the blast furnace.

[Table 1]

Θ _R , θ _{M U} , and C are constants that are substantially determined when the charging device and the charging material are determined, and can be regarded as constant values. On the other hand, θ
_m is a function of θ _R and the tilt angle of the turning chute, and was linearly approximated as follows from the measurement results (FIGS. 3 and 4). For coke, θ _m = -1.5 θ _R +50 For ore, θ _m = -1.5 θ _R +40

B and E are coefficients relating to the deposition position and the deposition depth, respectively, which are determined by the charging conditions. In this method, in the case of a blast furnace, a reduction model experiment is performed in advance,
Alternatively, it is possible to estimate the deposition shape of the furnace wall under all charging conditions with high accuracy by measuring basic data during burning and filling, when there is no wind.

[0016]

EXAMPLES Examples of the present invention will be shown below. Conventionally, the blast furnace A was operated by all coke, but it is now operated by blowing pulverized coal (hereinafter referred to as PC). For this reason, the ore / coke (hereinafter referred to as O / C) at the time of charging greatly changes from 3.5 to 4.2. For this reason, an appropriate charge distribution in the process of increasing the injection amount of PC is estimated in advance using this method, and the charge distribution is controlled by focusing on the O / C near the furnace wall. did.

FIG. 5 shows the actual measurement results by the profile meter and the deposition shape estimation results by the conventional method and the method of the present invention. With the conventional method A, the estimation accuracy is good for the charging methods that have been implemented in the past, but the estimation accuracy is considerably lower for the new charging method. In particular, a subtle change in O / C on the furnace wall could not always be accurately estimated. Further, the conventional method B can estimate with almost the same accuracy by any charging method, but the estimation accuracy itself is not so good.

On the other hand, with this method, any charging method can be estimated with high accuracy. Therefore, by this method, the deposit shape was estimated, and the distribution of the charge was controlled based on the result, and the smooth PC injection operation became possible.

[0019]

INDUSTRIAL APPLICABILITY The present invention uses a summation function of a Gaussian distribution function and a linear function in estimating the charge deposition shape of a vertical furnace. , Can be performed more accurately than the method based on linear approximation. This is particularly effective when the accuracy of estimating the deposition shape near the furnace wall is required, and has sufficient reliability as control data for a vertical furnace such as a blast furnace.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a deposition process of a charge.

FIG. 2 is a graph showing a deposition shape and a tilt angle of a charge in a vertical furnace.

FIG. 3 is a graph showing the relationship between θ _m and θ _{R in} coke.

FIG. 4 is a graph showing the relationship between θ _m and θ _{R in} ore.

FIG. 5 is a diagram comparing the measurement result of the profile meter with the conventional estimation method and the estimation method according to the present invention.

Claims (1)

[Claims] 1. When estimating the deposit deposition shape of the portion near the furnace wall from the drop point from the furnace top hopper, a summation function of a Gaussian distribution function and a linear function is assumed as the deposition shape,
Based on the data measured in advance by the charging device and the charging material, the deposition shape is determined by determining each coefficient of the function of the sum of the Gaussian distribution function and the linear function, and the loading in the vertical furnace is characterized. A method for estimating the shape of deposit accumulation.