Method for estimating coke strength and method for producing coke

Abstract

This method estimates the coke strength after volume modification without using a crushing method. [Solution] Coke is produced by varying the volume of molded coal in each of several identical blended coals. Base coke is produced from the base blended coal of each identical blended coal. The coke strength improvement effect is calculated for each coke. Based on the calculated coke strength improvement effect, equation (1) is formulated for each coke, and constants a to c are calculated. The coke strength improvement effect is obtained by substituting the void filling degree (-) of the pulverized coal and the void filling degree (-) of the blended coal of the coke whose coke strength is to be estimated into equation (1), and the multiplicative value is obtained by multiplying this by the mass ratio of molded coal. The coke strength is estimated by adding the multiplicative value to the coke strength of the coke made from the base blended coal as a raw material. Coke strength improvement effect = Void-filling degree of pulverized coal (-) × a + Void-filling degree of molded coal (-) × b + c ... Equation (1)

Description

[Technical Field]

[0001] This invention relates to a method for estimating coke strength, etc. [Background technology]

[0002] In conventional blast furnace coke production methods, various approaches have been explored to maintain good coke strength while increasing the proportion of inferior coal (such as non-coking coal) in the blended coal, which consists of molded coal and pulverized coal, as a countermeasure against the depletion of resources of high-quality, strongly coking coal. To obtain the desired coke strength using blended coal containing inferior coal, a coal pretreatment process may be useful.

[0003] The molded coal blending method, one of the coal pretreatment processes, improves the overall bulk density of the charged coal by blending in high-density molded coal, thereby improving coke strength. Furthermore, by utilizing the high density of the molded coal, it is possible to concentrate lower-grade coal within the molded coal without reducing coke strength. The molded coal blending method can also be combined with other coal pretreatment processes such as drying processes and crushing / particle size adjustment methods.

[0004] In the molded coal blending method, it is known that changing the volume of molded coal while keeping the blending ratio constant alters the bulk density of the blended coal (a mixture of molded coal and pulverized coal), thus changing the coke strength.

[0005] Patent Document 1 focuses on the fact that the relationship between the particle size of molded coal and coke strength changes depending on the degree of void filling (-) of the molded coal, and describes a method for producing coke in which the particle size of the molded coal used in the blend is adjusted according to the degree of void filling (-) of the molded coal. On the other hand, crushed molded coal has been used as the molded coal in many tests, and its particle size has been studied in a range smaller than that of ordinary molded coal.

[0006] In addition, the relationship between the particle size of formed coke and coke strength is organized using an index called the void filling degree (-) of formed coke. The void filling degree (-) of formed coke is calculated from the product of the expansion specific volume SV of formed coke and the bulk density of the blended coal. The void filling degree (-) of formed coke is an index representing the degree of adhesion between coal particles in formed coke during softening and melting. In Patent Document 1, however, the void filling degree (-) of formed coke is obtained using the bulk density of the blended coal instead of the density of formed coke, and formed coke and pulverized coal are treated together. Since the coke strength during the blending of formed coke is obtained from the weighted average of the coke strength of formed coke and the coke strength of pulverized coal, it is not preferable to treat formed coke and pulverized coal together. Furthermore, although the relationship between the particle size of formed coke and coke strength is organized assuming that the bulk density of the blended coal is constant, no organization has been done considering that the bulk density changes depending on the volume of formed coke.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0008]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] It is known that when the volume of formed coke is changed, the bulk density of the blended coal changes and the coke strength also changes. If the influence of the volume of formed coke on coke strength can be clarified, it becomes possible to narrow down the volume of desired formed coke from the viewpoint of coke strength.

[0010] As a prior art technique utilizing the crushing method, which is known as one method for adjusting the particle size of molded coal, there is also a known technique that organizes the relationship between the volume of crushed molded coal and the coke strength. However, the range of study regarding the volume of molded coal is narrow, and the crushing method has challenges such as the need to add crushers or sieving equipment and the difficulty of adjusting the particle size.

[0011] The present invention aims to estimate the coke strength after volume modification without using a crushing method when changing the volume of molded coal. [Means for solving the problem]

[0012] Characteristics of molded coal include its larger volume compared to pulverized coal and the use of binders such as coal tar during its production. A larger volume of molded coal makes it easier for the gases generated during softening and melting to be contained within the coal, increasing the void packing density (-) of the molded coal. When the void packing density (-) of the molded coal increases, the surrounding pulverized coal is compacted, increasing the void packing density (-) of the pulverized coal as well, and thus improving the coke strength. Therefore, it is thought that the void packing density (-) of the molded coal affects the change in coke strength when the volume of the molded coal is changed. Furthermore, the binder used during manufacturing has the effect of improving expansion, and this effect affects the molded coal and the surrounding pulverized coal. If the surrounding pulverized coal has low expansion properties, it is expected that the coke strength will improve due to the improvement in void filling degree (-) caused by the expansion-improving effect of the binder. In addition, when the volume of molded coal changes, the bulk density and void filling degree (-) of the pulverized coal also change. Therefore, it is thought that the void filling degree (-) of the pulverized coal also affects the change in coke strength when the volume of molded coal is changed.

[0013] The inventors have discovered the following method for estimating the coke strength after changing the volume of molded coal without using a crushing method. The coke strength estimation method of the present invention comprises: (1) A first coke production step in which, when a blend of coal having the same blending conditions for pulverized coal, the blending conditions for molded coal, and the mass ratio of molded coal is defined as a "same blended coal", multiple types of the same blended coal are prepared and coke is produced while changing the volume of molded coal within a predetermined range in each of the same blended coals; (2) A second coke production step in which multiple base blended coals are prepared in which the mass ratio of molded coal in each of the same blended coals is changed to 0 mass%, and coke is produced from each of these base blended coals; (3) A coke strength improvement effect calculation step in which the coke strength improvement effect is calculated for each coke produced in the first coke production step by dividing the difference between the coke strength of the coke produced in the first coke production step and the coke strength of the coke produced in the second coke production step by the mass ratio of molded coal; and (4) the coke The method is characterized by comprising: a constant calculation step in which, based on the coke strength improvement effect calculated in the strength improvement effect calculation step, the following equation (1) is formulated for each coke produced in the first coke production step, and constants a to c are calculated by performing regression analysis on these equations (1); and a coke strength estimation step in which, when coke made from blended coal A containing pulverized coal and molded coal is defined as coke A, and coke made from blended coal B in which the mass ratio of molded coal in blended coal A is changed to 0 mass%, the coke strength improvement effect of coke A is determined by substituting the void filling degree (-) of pulverized coal and the void filling degree (-) of molded coal in blended coal A into equation (1), and a multiplicative value is obtained by multiplying the coke strength improvement effect of coke A by the mass ratio of molded coal in blended coal A, and the coke strength of coke A is estimated by adding this multiplicative value to the coke strength of coke B.

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[0014] (2) The method for estimating coke strength as described in (1) above, characterized in that the void packing degree (-) of pulverized coal is the product of the expansion specific volume of pulverized coal and the bulk density of pulverized coal, and the void packing degree (-) of molded coal is the product of the expansion specific volume of molded coal and the apparent density of molded coal.

[0015] (3) The predetermined range is 4 cm 3 More than 130cm 3 The method for estimating coke strength according to (1) or (2) above, characterized in that it is as follows:

[0016] (4) A method for producing coke A using the coke strength estimation method described in any one of (1) to (3) above, wherein when blended coal A is defined as blended coal C which includes pulverized coal and molded coal, the volume of molded coal in blended coal C is changed from volume V1 to volume V2, the method includes a determination step of determining the volume V2 of molded coal in blended coal A and the mass ratio of molded coal so as to satisfy the target coke strength and so as to not be lower than a predetermined amount by which the bulk density of blended coal A is produced compared with the bulk density of blended coal C, and in the determination step, the coke strength estimation step confirms that the target coke strength is satisfied. [Effects of the Invention]

[0017] According to the present invention, the coke strength after changing the volume of molded coal can be estimated without using a crushing method. [Brief explanation of the drawing]

[0018] [Figure 1] This is a flowchart showing the procedure for estimating coke strength. [Figure 2] This graph shows the relationship between measured and estimated values ​​for the coke strength improvement effect. [Figure 3] This graph shows the relationship between measured and estimated coke strength values. [Modes for carrying out the invention]

[0019] One embodiment of the present invention will be described below with reference to the drawings.

[0020] Figure 1 is a flowchart showing the procedure for the coke strength estimation method of the present invention. The coke strength estimation method of the present invention includes "Step S101: First coke production step," "Step S102: Second coke production step," "Step S103: Coke strength improvement effect calculation step," "Step S104: Constant calculation step," and "Step S105: Coke strength estimation step." Each step will be described in detail below.

[0021] (Step S101: First coke production step) Coal blends in which the blending conditions for powdered coal, the blending conditions for molded coal, and the mass ratio of molded coal are all the same are defined as identical blended coals. "The blending conditions of the pulverized coal are identical" means that the blending ratio of each type of coal that makes up the pulverized coal is the same for all of them. "The blending conditions of the molded coals are identical" means that the blending ratios of each type of coal and the blending ratio of the binders that make up the molded coal are identical. If the binders are a mixture of liquid and solid types, the blending ratios of the liquid binders and the solid binders are identical. The "mass ratio of molded coal" refers to the mass of molded coal contained in the blended coal, expressed as a percentage. The blended coal defined in step S101 consists of powdered coal and molded coal.

[0022] In step S101, several types of the same type of coal blend described above are prepared, and coke is produced in each type of the same type of coal blend while varying the volume of molded coal within a predetermined range. At least one of the following differs among the several types of the same type of coal blend: the blending conditions of the pulverized coal, the blending conditions of the molded coal, and the mass ratio of the molded coal. The specified range is 4 cm 3 More than 130cm 3 The following may also be used. This is consistent with the volume range of commonly used molded charcoal. However, 4 cm 3 More than 130cm 3 The following ranges may be exceeded in the amount of molded charcoal included.

[0023] The number of types of charcoal blends prepared can be multiple. In the example described later, five types of charcoal blends (charcoal blends X1 to X5) were prepared, but the present invention is not limited to this.

[0024] The number of times the volume of the molded coal is changed in each of the same type of coal blends may be the same or different. In the examples described later, the number of times the volume of coal blends X1 and X4 is changed is 4, and the number of times the volume of coal blends X2, X3 and X5 is changed is 3, but the present invention is not limited to this. Furthermore, the volume of molded charcoal prepared for each type of charcoal blend may be the same or different.

[0025] (Step S102: Second coke production step) In step S102, multiple base blends are prepared, each with the mass ratio of molded coal changed to 0% by mass, and coke is produced from each of these base blends. The "blended coal with the mass ratio of molded coal changed to 0% by mass" consists only of pulverized coal, and the blending conditions of the pulverized coal are the same as those of the original blend. Therefore, the base blends in step S102 consist only of pulverized coal, and the number of base blends prepared is equal to the number of types of blends.

[0026] For example, in the embodiment described later, base blended coals X01 to X05 corresponding to each of the five types of identical blended coals X1 to X5 were prepared, and coke was produced from each of the base blended coals X01 to X05.

[0027] The terms "first" and "second" in the first coke production step (step S101) and the second coke production step (step S102) are not ordinal numbers indicating order. Therefore, the order of steps S101 and S102 is not particularly limited. For example, steps S101 and S102 may be performed for each type of coal blend.

[0028] (Step S103: Step to calculate the coke strength improvement effect) The coke strength improvement effect is calculated for each batch of coke produced in step S101 by dividing the difference between the coke strength of the coke produced in step S101 and the coke strength of the coke produced in step S102 by the mass ratio of the molded coal. In other words, in step S103, the increase in coke strength per 1% by mass of molten coal is calculated for each coke produced in step S101. In this specification, this increase in coke strength per 1% by mass of molten coal will be referred to as the "coke strength improvement effect".

[0029] For example, in the aforementioned identical blended coal X1, four identical blended coals X1 with different volume values ​​of molded coal are prepared. Coke is produced from each of these identical blended coals X1, and the coke strength is determined for each of these cokes. Then, the difference between the coke strength of each coke and the coke strength of the coke produced from the base blended coal X01 is calculated, and by dividing this difference by the mass ratio of molded coal contained in the identical blended coal X1, the coke strength improvement effect is calculated for each coke. The coke strength improvement effect can be calculated for the same type of coal blend X2 to X5 using the same procedure.

[0030] The coke strength may be a measured value obtained from drum tests or other methods, or it may be an estimated value obtained from a weighted average of the pulverized coal strength and the molded coal strength. The method for calculating this estimated value is disclosed in Patent Document 2, so a detailed explanation is omitted.

[0031] (Step S104: Constant calculation step) Based on the coke strength improvement effect calculated in the coke strength improvement effect calculation step (step S103), the following equation (1) is formulated for each coke produced in the first coke production step (step S101), and constants a to c are calculated by performing regression analysis on these equations (1).

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[0032] The void filling degree (-) of pulverized coal can be determined by "expansion specific volume SV (cm 3 / g) of pulverized coal × bulk density (g / cm 3 )" of pulverized coal. The void filling degree (-) of formed charcoal can be determined by "expansion specific volume SV (cm 3 / g) of formed charcoal × apparent density (g / cm 3 )" of formed charcoal.

[0033] The expansion specific volume SV (cm 3 / g) of pulverized coal can be measured by, for example, a carbonization test using a dilatometer. The same applies to the expansion specific volume SV (cm 3 / g) of formed charcoal. The apparent density (g / cm 3 ) of formed charcoal can be measured by, for example, an apparent specific gravity measuring device.

[0034] The bulk density (g / cm 3 ) of pulverized coal can be calculated from, for example, the following formula (2) described in Non-Patent Document 2.

Equation

[0035] Expansion specific volume SV (cm 3The expansion specific volume SV (cm³) is affected by the blending conditions of powdered coal and molded coal, and even if the volume value of molded coal changes, the specific volume SV (cm³) will not change. 3 The expansion ratio SV (cm³) does not change. Therefore, for identical blended coals with the same blending conditions but different volume values ​​of molded coal, the expansion ratio SV (cm³) remains unchanged. 3 / g) are identical. On the other hand, the bulk density of pulverized coal (g / cm³) depends on the volume of molded coal. 3 ) and the apparent density (g / cm³) of molded charcoal 3 Because this changes, identical blends of coal with different volumes of molded coal will have different degrees of void filling (-) of the pulverized coal. Similarly, identical blends of coal with different volumes of molded coal will have different degrees of void filling (-) of the molded coal.

[0036] Therefore, for the aforementioned identical coal blend X1, it is necessary to determine the void filling degree (-) of the pulverized coal and the void filling degree (-) of the molded coal for each of the four identical coal blends X1 with different volumes of molded coal. The same applies to other identical coal blends.

[0037] Multiple regression analysis can be used for regression analysis. Multiple regression analysis may also be performed using the least squares method. By conducting multiple regression analysis with the coke strength improvement effect as the dependent variable and the void filling degree of pulverized coal (-) and the void filling degree of molded coal (-) as independent variables, constants a to c can be calculated.

[0038] Here, we define coke made from blended coal A, which includes pulverized coal and molded coal, as Coke A, and coke made from blended coal B, which is obtained by changing the mass ratio of molded coal in blended coal A to 0% by mass, as Coke B. Blended coal B consists only of pulverized coal, and the blending conditions for pulverized coal are the same as those for blended coal A. In this invention, the coke strength of coke A is estimated by the following coke strength estimation steps, without using a crushing method.

[0039] (Step S105: Coke strength estimation step) By substituting the void packing degree (-) of the pulverized coal and the void packing degree (-) of the molded coal in blended coal A into equation (1), the coke strength improvement effect of coke A is determined. At the same time, the coke strength improvement effect of coke A is multiplied by the mass ratio of the molded coal in blended coal A to obtain a multiplicative value, and by adding this multiplicative value to the coke strength of coke B, the coke strength of coke A is estimated.

[0040] Needless to say, equation (1) is the equation obtained after the constants a to c have been determined in the constant calculation step (step S104). By substituting the void packing degree (-) of the pulverized coal of blended coal A and the void packing degree (-) of the molded coal of blended coal A into this equation (1), the coke strength improvement effect of coke A is determined. The method for calculating these void packing degrees (-) will not be explained again.

[0041] Since the coke strength improvement effect is the increase in coke strength per 1% by mass of molded coal, the increase in coke strength due to the inclusion of molded coal (corresponding to the multiplicative value mentioned above) can be obtained by multiplying the coke strength improvement effect by the mass ratio of molded coal contained in blended coal A. Therefore, by adding this increase to the coke strength of coke B (coke made from blended coal B without molded coal), the coke strength of coke A can be estimated. The coke strength of coke B may be a measured value or an estimated value. The methods for determining the measured and estimated values ​​will not be repeated.

[0042] According to this embodiment, by using the degree of void filling (-) of pulverized coal and molded coal, the coke strength after changing the volume of molded coal can be estimated without using a crushing method. Therefore, the volume of molded coal that satisfies the desired coke strength can be easily determined.

[0043] By using the coke strength estimation method described above, it is possible to produce coke A that satisfies the desired production volume and target coke strength. Specifically, the above-described coke strength estimation method can be used when producing coke by changing blended coal C to blended coal A. Blended coal C is a blend containing pulverized coal and molded coal, and blended coal A is the blend obtained by changing the volume of molded coal contained in blended coal C from V1 to V2. The volume V2 of molded coal and the blending ratio of molded coal are determined so as to satisfy the target coke strength and so as to ensure that the bulk density of blended coal A does not fall below the bulk density of blended coal C by more than a predetermined amount during coke production. If the target coke strength is confirmed to be satisfied using the coke strength estimation method described above, then coke A that satisfies the desired production volume and target coke strength can be produced. A lower bulk density results in a decrease in coke production. Therefore, the "determined amount" should be determined appropriately based on the desired production volume.

[0044] (Examples) The present invention will be specifically described below with reference to examples. The coke strength improvement effect of blended coal, which was produced by mixing pulverized coal with molded coal, was evaluated by carbonization tests using a test coke oven. Table 1 shows the properties of each coal A to L used, namely the volatile content VM (mass%) and total expansion rate TD (%). The volatile content VM (mass%) was based on the dry basis (the same applies to the volatile content ΣVM (mass%) of pulverized coal and molded coal, as described later). [Table 1]

[0045] Table 2 shows the blending conditions 1-4 for the powdered coal, the properties of the powdered coal (volatile content ΣVM (mass%), total expansion coefficient ΣTD (%), and expansion specific volume SV (cm³). 3 The values ​​shown are per g. Powdered coal blending condition 1 had a moisture content of 4 or 10% by mass, powdered coal blending condition 2 had a moisture content of 4% by mass, powdered coal blending condition 3 had a moisture content of 10% by mass, and powdered coal blending condition 4 had a moisture content of 4% by mass. In all cases, the crushed particle size was 3 mm, with a sieving ratio of 85% by mass. [Table 2]

[0046] Table 3 shows the compounding conditions 1-4 for the molded charcoal, as well as the properties of the molded charcoal: volatile content ΣVM (mass%), total expansion coefficient ΣTD (%), and expansion specific volume SV (cm³). 3 The values ​​shown are per g. Molded charcoal was produced by molding powdered charcoal with a particle size of 3 mm and a sieving ratio of 90% by mass, in a molding machine according to the molding charcoal mixing conditions 1 to 4. A tar-based binder was used as the liquid binder, and asphalt pitch (ASP) was used as the solid binder. The volumes of the molded charcoal were 4, 8, 18, 38, and 130 cm³. 3 (Equivalent to a particle size of 20, 25, 33, 42, or 63 mm) [Table 3]

[0047] The expansion ratio volume SV (cm³) of powdered coal and molded coal shown in Tables 2 and 3. 3 The volume ( / g) was obtained by carbonization test using a dilartometer. Powdered coal, according to the specified blending conditions, was sieved to a 3mm sieve with a 100% mass ratio, then placed in a reaction tube and subjected to carbonization test under heating conditions of 3°C / min. The sample height in the reaction tube was 60mm. The same carbonization test was performed on molded coal. Expansion specific volume SV (cm³) of powdered coal was also obtained. 3 In the measurement, the bulk density was 0.85 g / cm³ on a dry basis. 3 ) and the expansion specific volume SV (cm³) of the molded charcoal. 3 In the measurement, the bulk density was 1.10 g / cm³ on a dry basis. 3 )

[0048] Coke was produced by carbonizing a blend of pulverized coal and molded coal, prepared under the conditions of levels 1 to 22 shown in Table 4, in a test coke oven. Each coke was then subjected to a drum test to determine its coke strength (DI). 150 A reading of 6(-) was measured. [Table 4]

[0049] Apparent density of molded charcoal (g / cm³) 3 The apparent specific gravity was measured using an apparent specific gravity measuring device. Bulk density of powdered coal (g / cm³) 3 ) is determined by a bulk density measurement test, which determines the bulk density ρ (g / cm³) of the blended coal. 3 The following were measured and calculated from equation (2). For the bulk density measurement test machine, an improved machine conforming to ASTM D 291-86 was used, with improvements made to the drop height, hopper shape, and slide valve area.

[0050] The drum test conditions were: rotation speed: 150 rpm, N=3. The bulk density of the blended coal measured with the bulk density measuring machine described above was multiplied by 0.05 (dry-g / cm³). 3 By adding and correcting the charging density (g / cm³), 3 The following was calculated. This correction takes into account the low furnace height of the test furnace and is intended to obtain equivalent coke strength in the test furnace and the actual furnace.

[0051] At each of the following levels, levels 2-5, 7-9, 11-13, 15-18, and 20-22, the expansion ratio volume SV (cm³) of pulverized coal was determined. 3 (g) and bulk density of pulverized coal (g / cm³) 3 The degree of void filling (-) of the pulverized coal is calculated by multiplying by ) and the expansion specific volume SV (cm³) of the molded coal is calculated. 3 (g) and apparent density of molded charcoal (g / cm³) 3 The degree of void filling (-) of the molded coal was calculated by multiplying by ).

[0052] Coke strength (DI) of coke produced from the same type of coal blend 150 6) Coke strength (DI) of coke produced from base blended coal. 150 6) The difference (in other words, the DI due to the composition of the molded charcoal) 150 The improvement (-) for level 6 was determined, and by dividing this difference by the mass ratio of the molded coal, the coke strength improvement effect for each level, levels 2-5, 7-9, 11-13, 15-18, and 20-22, was calculated. The results are shown in Table 5. [Table 5] It can be seen that the degree of void filling (-) in pulverized coal and the degree of void filling (-) in molded coal affect the coke strength improvement effect.

[0053] The above equation (1) is reproduced below.

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[0054] Using the regression coefficient, which is the slope of the obtained regression equation, we derived a relationship between the void packing degree (-) of pulverized coal and molded coal and the coke strength improvement effect. At this time, the significance level was set to 5% (0.05), which is common in multiple regression analysis. When the multiple regression analysis was performed with the intercept significantly different from 0, the p-value of the intercept exceeded the significance level, so the multiple regression analysis was performed again with the intercept not significantly different from 0 (i.e., intercept = 0), and the obtained results were adopted. Substituting the constants a to c into equation (1), the following equation (3) was obtained.

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[0055] The above multiple regression analysis has a significance level of 3.9 × 10 in the analysis of variance. -12 Since the value was less than 0.05, we determined that regression analysis was meaningful. Furthermore, the P-values ​​for the void packing degree (-) of pulverized coal and the void packing degree (-) of molded coal were 0.0082 and 2.1 × 10⁻⁶, respectively. -6 Since all of these values ​​are less than 0.05, we determined that each regression coefficient is significant.

[0056] Furthermore, it was confirmed in advance that there was no strong correlation between the void packing degree (-) of pulverized coal and the void packing degree (-) of molded coal, which were used as explanatory variables, by the following method. Specifically, in the graph showing the relationship between the void packing degree (-) of pulverized coal and the void packing degree (-) of molded coal, a simple linear regression was performed using the least squares method from the plotted values ​​to obtain the regression equation, and the coefficient of determination (R) of the regression equation was calculated. 2 The coefficient of determination was then calculated. Then, the tolerance (=1-R) was calculated using the obtained coefficient of determination. 2 We confirmed that ) is greater than 0.1.

[0057] The void filling degree (-) of pulverized coal and molded coal at levels 2-5, 7-9, 11-13, 15-18, and 20-22 was substituted into equation (3) to determine the estimated coke strength improvement effect. The relationship between the measured coke strength improvement effect and the estimated coke strength improvement effect is summarized in Figure 2. The measured coke strength improvement effect refers to the coke strength improvement effect (- / %) listed in Table 5.

[0058] The coke strength improvement effect (estimated value) is multiplied by the mass ratio of molded coal to obtain a multiplicative value, and this multiplicative value is added to the coke strength of the base blended coal coke to obtain the coke strength (DI) for each level 2-5, level 7-9, level 11-13, level 15-18, and level 20-22. 150 6) was estimated.

[0059] Estimated coke strength (DI) 150 6) and measured coke strength (DI 150 The relationship with 6) is summarized in Figure 3. Measured coke strength (DI) 150 6) refers to the coke strength (DI) shown in Table 4. 150 6) This refers to the fact that, as shown in Figure 3, the coke strength can be estimated with high accuracy using equation (3).

[0060] If equation (3) and the coke strength of coke produced from the base blended coal are determined in advance, the coke strength improvement effect can be calculated by substituting the void packing degree (-) of the pulverized coal and the void packing degree (-) of the molded coal into equation (3) when changing the volume of molded coal. It was found that the calculated coke strength improvement effect can be used to accurately estimate the coke strength after the volume change.

[0061] Although the present invention has been described above with reference to the examples, the present invention is not limited to the above examples. Inventions modified without departing from the spirit of the present invention, and inventions equivalent to the present invention, are also included in the scope of the present invention. For example, in the "coke strength improvement effect calculation step" of the present invention, the increase in coke strength per 1% by mass of molded coal is defined as the "coke strength improvement effect," but the increase in coke strength per K% by mass of molded coal may also be defined as the "coke strength improvement effect" (modification). "K" is a real number (such as a natural number) other than 1. Such modifications are included in the scope of the present invention as equivalent inventions. When K=5, the "coke strength improvement effect" is calculated by dividing the difference between the coke strength of the coke produced in the first coke production step and the coke strength of the coke produced in the second coke production step by the mass ratio of molded coal, and then multiplying by 5.

Claims

1. When a blend of coal having the same blending conditions for pulverized coal, the same blending conditions for molded coal, and the same mass ratio of molded coal is defined as a "same type blended coal," the first coke production step involves preparing multiple types of the same type blended coal and producing coke while varying the volume of molded coal within a predetermined range for each type of blended coal, A second coke production step involves preparing multiple base blends of coal in which the mass ratio of molded coal in each of the same type of blended coal is changed to 0% by mass, and producing coke from each of these base blends. A coke strength improvement effect calculation step is performed to calculate the coke strength improvement effect for each coke produced in the first coke production step, by dividing the difference between the coke strength of the coke produced in the first coke production step and the coke strength of the coke produced in the second coke production step by the mass ratio of molded coal, Based on the coke strength improvement effect calculated in the coke strength improvement effect calculation step, A constant calculation step is performed in which, for each coke produced in the first coke production step, the following equation (1) is formulated, and these equations (1) are subjected to regression analysis to calculate constants a to c. When we define coke made from blended coal A, which includes powdered coal and molded coal, as coke A, and coke made from blended coal B, in which the mass ratio of molded coal in blended coal A is changed to 0% by mass, The coke strength estimation step involves substituting the void filling degree (-) of the pulverized coal and the void filling degree (-) of the molded coal of blended coal A into equation (1) to determine the coke strength improvement effect of coke A, multiplying the coke strength improvement effect of coke A by the mass ratio of the molded coal of blended coal A to determine a multiplicative value, and adding this multiplicative value to the coke strength of coke B to estimate the coke strength of coke A. A method for estimating coke strength, characterized by having [a certain feature]. [Math 1]

2. The void-filling ratio (-) of pulverized coal is the product of the expansion specific volume of the pulverized coal and the bulk density of the pulverized coal. The void-filling ratio (-) of molded coal is the product of the expansion specific volume of the molded coal and the apparent density of the molded coal. The method for estimating coke strength according to feature 1.

3. The aforementioned predetermined range is 4 cm ３ 130cm or more ３ The method for estimating coke strength according to claim 1 or 2, characterized as follows:

4. A method for producing coke A using the coke strength estimation method described in claim 1 or 2, When the blended coal A is defined as a blended coal in which the volume of molded coal in blended coal C, which includes powdered coal and molded coal, is changed from volume V1 to volume V2, The method includes a determination step of determining the volume V2 of molded coal in blended coal A and the mass ratio of molded coal so as to satisfy the target coke strength and so as to ensure that the bulk density of blended coal A during coke production is not lower than the bulk density of blended coal C by a predetermined amount or more. In the aforementioned decision step, the coke strength estimation step confirms that the target coke strength is satisfied. A method for producing coke, characterized by the following features.

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