JPH071269B2 - Blast furnace coke strength estimation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for estimating and controlling the strength of blast furnace coke when carbonizing and producing coal in a coke oven.

<Prior Art> The pulverization property of blast furnace coke has a great influence on the operation of the blast furnace. If the pulverization property is increased, the ventilation resistance in the furnace is increased, which leads to an abnormal drop of the charge such as shelf hanging or slip of the charge, which adversely affects the operation of the blast furnace. Therefore, coke dusting property management is an important task in the coke manufacturing department.

The tumbler test is one of the typical methods for evaluating coke dusting characteristics, and it is specified in JIS. For example, a mass of coke is put in a tumbler tester, and a +6 mm yield after 400 rotations is referred to as TI ₆ ⁴⁰⁰ , which is used as an index indicating coke abrasion resistance. Correspondence between the index and the blast furnace ventilation resistance coefficient is often emphasized.

However, the method of predicting the tumbler strength index by controlling the lime property value widely used in the coke manufacturing department within a predetermined range has not been able to perform highly accurate prediction / control. This is natural because the coke oven furnace operating conditions are changing even under the same composition.

For this reason, it has been attempted to predict the relationship between the tumbler strength index and operating conditions by using multiple regression analysis, etc., but the effect of each factor of coal property factor, coke oven structure factor and coke oven operation factor cannot be separated. ,
Prediction accuracy was remarkably low only by analyzing daily data.

Meanwhile tumbler strength index, for example, the components of the TI ₆ ⁴⁰⁰ is in the porosity and pore wall strength are well known in the art.
Thus the porosity and pore wall thickness, respectively coal properties factors, the prediction accuracy of the TI ₆ ⁴⁰⁰ Te by the quantifying the relationship between the coke oven structure factor and coke oven operation factor can be expected. In that case, there is no problem in measuring the porosity, but there is no method for accurately measuring the porosity wall strength. For example, there is a method called micro strength test,
In this method, coke is crushed to a particle size of 1 to 2 mm to remove internal cracks, and the wear strength of particles is measured. However, as can be seen from the particle size composition of -6 mm after the tumbler test (Table 1), there are 50 particles of 0.25 mm or less.
When the particle size is 0.25 mm, the average pore wall thickness is 0.
It is on the order of 1 to 0.2 mm, and the test coke grain size of 1 to 2 mm in the micro strength test has a form in which pores are built in, and the influence of porosity cannot be completely separated. Therefore, when the micro strength index (MSI) is adopted as the pore wall strength index, for example, when the porosity increases and the pore wall strength increases, the change in MSI value is canceled by both, and the apparent pore wall The increase in strength is small. In addition, when the porosity decreases and the pore wall strength increases, the increase in MSI value due to the decrease in porosity is also counted, so the apparent pore wall strength significantly increases. Therefore, the coke tumbler strength index
As long as the MSI value is used as the parameter of the TI estimation formula, the effect of porosity and pore wall strength cannot be separated, and therefore TI ₆ ⁴⁰⁰ cannot be estimated with high accuracy.

<Problems to be Solved by the Invention> The present invention separates the effects of porosity and pore wall strength on the tumbler strength index TI, and provides a more accurate estimation method of blast furnace coke strength, and further operation of the coke oven. It is intended to provide a coke strength control method for a blast furnace that facilitates adjustment of conditions.

<Means for Solving the Problems> In the present invention, when determining the tumbler strength index (TI) of coke, first, the operating conditions of the coke oven are at least the fluidity (MF) of the charging coal, the carbonization rate (HR), and The pore wall embrittlement index (Pai) of coke was estimated from the bulk density (BD) according to a predetermined equation (1), and at least the average reflectance ( ₀ ) and bulk density of the charging coal, which is the operating condition of the coke oven, were estimated. The coke porosity (Por) is estimated from (BD) according to a predetermined equation (2), and using these two values,
This is a method for estimating the blast furnace coke strength by estimating the tumbler strength index (TI) of the coke using the equation (3).

_{Pai = (a 1 · HR +} a 2) × MF + (a 3 · 0 2 + a 4 · 0 +
_{a 5) × 0 + a 6} × BD + a 7 × HR + a 8 × DP + a 9 ...... (1) Por = (b 1 · HR + b 2) × MF + (b 3 · 0 2 + b 4 · 0 +
_{a 5) × 0 + b 6} × BD + b 7 × HR + b 8 × DP + b 9 ...... (2) (1), (2) estimate equation of TI (3) was obtained by the equation.

TI = C ₁ Pai + C ₂ Por + C ₃ (3) where MF: Fluidity of the charging coal defined by the logarithm of Gisler maximum fluidity (ddpm) ₀ : Average reflectance of blended coal (-) HR: Carbonization Speed (mm / hr) BD: Bulk density (kg / m ³ ) DP: Grain size of blended coal −3 mm% a _{1 to} a ₉ , b _{1 to} b ₉ , C ₁ , C ₂ , C ₃ are constants, respectively. .

Further, according to the present invention, the carbonization rate (HR), which is the operating condition of the coke oven, is set so that the tumbler strength index (TI) according to the equation (3) estimated based on the operating condition of the coke oven falls within a predetermined target control value. Flowability of charged coal (MF), bulk density (B
This is a method for controlling the strength of blast furnace coke by adjusting one or more of D) and the average reflectance ( ₀ ).

<Operation> The present invention tumbler strength index useful coke for blast furnace operation, for example, to predict and manage TI ₆ ⁴⁰⁰ with high accuracy, to assess the Kikabe strength of the coke which is a component of TI ₆ ⁴⁰⁰ with high precision A method was discovered, and the coke oven operating conditions were related to the TI prediction formula that incorporated the pore wall strength and porosity.

Generally, as a method for evaluating the pore wall strength of coke, a micro strength test method is well known. However, since the test coke diameter of 1 to 2 mm is used in this method, as shown in Table 1, TI ₆ 0.25mm generated at an efficiency of about 50-60% at ⁴⁰⁰ measurements
Since the effect of pores composed of pore walls of the order of 0.1 to 0.2 mm, which causes powder, cannot be separated, the effect of porosity is mixed in, which is not preferable as a parameter of pore wall strength.

On the other hand, there is an indirect tensile strength test method as a method for evaluating the coke strength as a porous body. This test method is a method in which a core sample of, for example, D ^φ × t ^H is cut out from a lump coke and a tensile strength (σ _f ) is calculated by a crushing test.

ceremony However, W is a breaking load. As shown in FIG. 2, the present inventors have a relatively good correlation between TI ₆ ^{400 and} the logarithmic value (log σ _f ) of this tensile strength, and 10 ^φ × 5 from the coke taken out from the coke oven. A plurality of core samples of ^H mm were cut out, and the coke porosity Por and the tensile strength logarithmic value (log
Results of measurement of sigma _f), logarithm Logshiguma _f and porosity Por tensile strength as in FIG. 3 is that there is a good correlation, and the fourth
As shown in the figure, it was discovered that in coke produced under different manufacturing conditions, the rate of change in logarithmic log σ _f of tensile strength corresponding to the change in porosity Por, that is, the slope θ of both regression lines, was different.

Therefore, the porosity (Por) of multiple core samples obtained from blast furnace coke and the slope of the regression line with the logarithmic value of the tensile strength indirectly obtained from the same core sample by the crushing test were used to determine the pore wall embrittlement index Pai. That is, Pai = −d (logσ _f ) / d (P
or) and attempted to estimate the tumbler strength index TI ₆ ^{400 using} a linear equation together with the porosity Por, and a very good correspondence with the measured value was obtained.

From this, the coke porosity wall embrittlement index Pai obtained from the relationship between the coke porosity Por and the logarithm of tensile strength was obtained as the porosity wall strength index of agglomerated coke. It was found that by quantifying the factor relationships with the coke oven structure factor and the coke oven operation factor in advance, it is possible to predict and manage the variation of coke TI ₆ ⁴⁰⁰ due to the oven operation variation with high accuracy.

That is, the present inventors diligently studied the relationship between the operating conditions of coke and Pai and Por, and as a result, a block diagram as shown in FIG. 7 was obtained, and the marks in the figure indicate significant parameters especially for Pai and Por. It turned out to be Next, these relationships were applied to a predetermined coke oven and quantified by a known statistical method to obtain equations (1) and (2).

_{Pai = (a 1 · HR +} a 2) × MF + (a 3 · 0 2 + a 4 · 0 +
_{a 5) × 0 + a 6} × BD + a 7 × HR + a 8 × DP + a 9 ...... (1) Por = (b 1 · HR + b 2) × MF + (b 3 · 0 2 + b 4 · 0 +
_{a 5) × 0 + b 6} × BD + b 7 × HR + b 8 × DP + b 9 ...... (2) (1), (2) estimate equation of TI (3) was obtained by the equation.

TI = C ₁ Pai + C ₂ Por + C ₃ (3) where MF: Fluidity of the charging coal defined by the logarithm of Gisler maximum fluidity (ddpm) ₀ : Average reflectance of blended coal (-) HR: Carbonization Speed (mm / hr) BD: Bulk density (kg / m ³ ) DP: Grain size of blended coal −3 mm% a _{1 to} a ₉ , b _{1 to} b ₉ , C ₁ , C ₂ , C ₃ are constants, respectively. .

As a parameter of the empirical formula of Pai and Por, both
HR, MF, ₀ , BD, DP are adopted, but not limited to this, and at least HR, MF, B as parameters of Pai.
It has been confirmed that TI can be estimated with higher accuracy than in the conventional method by adopting D and ₀ or BD as the parameter of Por.

<Examples> Under the production conditions of I to V shown in Table (2), the test coal was subjected to dry distillation in an electric furnace of a chamber furnace type of 40 kg to obtain agglomerated coke, and to obtain average characteristics of the coke. Head the coke,
The body and legs are divided into three parts, and 20 core samples (10 ^φ
X 5 ^H mm) was sampled and the porosity and tensile strength were measured. At the same time, a micro strength test and a tumbler test were performed on the remaining sample. Table 3 collectively shows these results including the pore wall embrittlement index according to the present invention. Using the results in Table 3
The results of examining the relationship between TI ₆ ⁴⁰⁰ shown in FIG. 5 and FIG. 6. In FIG. 5 in which the method of the present invention is adopted, the calculated value of TI ₆ ⁴⁰⁰ and the measured value are in good agreement. However, when TI is estimated by the equation (4) using micro strength and porosity as parameters,
As shown in Fig. 6, the effect of porosity seen in Cases III, IV, and V is not completely separated (high MSI), and the pore wall strength is counted as a high value, which corresponds to TI ₆ ^400. It is inferior to FIG. 5 of the present invention.

TI = d ₁ MSI ＋ d ₂ Por ＋ d ₃ …… (4) Next, under the production conditions shown in Table 4 I, when producing agglomerated coke by dry-distilling the test coal in an actual furnace charged with 12 tons, the TI estimation formula ( When the tumbler strength index of the coke produced using 1), (2), and (3) was estimated, it was 1.0 lower than the target control value of TI. Therefore, the estimated value of TI should be the target control value. The coke was manufactured by changing the manufacturing conditions as shown in No. II. The tumbler test result of the coke produced, TI ₆ ^400, was only 0.1 higher than the target control value, which was a level at which there was no practical problem.

Furthermore, Figure 1 shows the estimated and measured values of the 12-charge tumbler strength TI in a specific coking chamber of a coke oven at a specific factory, and it was found that it can be used with considerable accuracy in actual operation.

<Effect of the Invention> As described above, according to the present invention, the tumbler TI of the blast furnace coke is
₆ ⁴⁰⁰ not only stable contribute prediction-manageable and become blast furnace operation with high accuracy, can contribute significantly to the flexibility reduce coking coal costs enables increased formulation of increasing low-quality coal in a coke oven formulation side.

[Brief description of drawings]

FIG. 1 is a diagram showing the effect of the present invention in an actual operation coke oven,
Correlation diagram between logarithmic and TI ₆ ⁴⁰⁰ in FIG. 2 tensile strength, Fig. 3 is a correlation diagram between the logarithm of the tensile strength and porosity, Fig. 4 and tensile porosity showing the basis for the pore walls embrittlement index Correlation diagram with logarithm of intensity, FIG. 5 is a graph showing a comparison between the measured value of TI ₆ ⁴⁰⁰ and the estimated value according to the present invention, and FIG. 6 is a comparison between the measured value of TI ₆ ⁴⁰⁰ and the estimated value according to the conventional method. Fig. 7 is a block diagram of coke oven operating conditions affecting TI.

Claims (2)

[Claims] 1. When estimating the tumbler strength index (TI) of coke, the coke flow rate (MF), carbonization rate (HR), and bulk density (BD), which are operating conditions of the coke oven, are used to estimate the coke. The pore wall embrittlement index (Pai) was estimated according to a predetermined equation (1), and the porosity of coke was calculated from at least the average reflectance ( ₀ ) and bulk density (BD) of the charging coal, which are operating conditions of the coke oven. (Por) is estimated according to a predetermined equation (2), and the tumbler strength index (TI) of the coke is estimated by the equation (3) using these two values, and a method for estimating coke strength for a blast furnace is provided. . _{Pai = (a 1 · HR +} a 2) × MF + (a 3 · 0 2 + a 4 · 0 +
_{a 5) × 0 + a 6} × BD + a 7 × HR + a 8 × DP + a 9 ...... (1) Por = (b 1 · HR + b 2) × MF + (b 3 · 0 2 + b 4 · 0 +
defined Gisura maximum fluidity of logarithm _{(ddpm): b 5) ×} 0 + b 6 × BD + b 7 × HR + b 8 × DP + b 9 ...... (2) TI = C 1 Pai + C 2 Por + C 3 ...... (3) where MF Fluidity of charged coal ₀ : Average reflectance of blended coal (-) HR: Dry distillation rate (mm / hr) BD: Bulk density (kg / m ³ ) DP: Grained grain size of blended coal-3mm% a ₁ ~ a _{9, b 1 ~b 9, C} 1, C 2, C 3 are respectively constant. 2. The carbonization rate (HR), which is the operating condition of the coke oven, and the equipment so that the tumbler strength index (TI) of claim 1 estimated based on the operating condition of the coke oven falls within a predetermined target control value. A method for controlling the strength of blast furnace coke, which comprises adjusting at least one of the fluidity (MF), bulk density (BD) and average reflectance ( ₀ ) of coal feeding.