Method for evaluating the extrusion properties of coke cake and method for manufacturing coke cake

Abstract

To provide a method for evaluating coke cake extrudability that evaluates the coke cake extrudability.SOLUTION: Three-dimensional image data is generated by performing X-ray photography on a coke cake produced by carbonizing coking coal to be evaluated using a test coke oven. Crack surfaces located at a boundary of two adjacent coke lumps contained in the coke cake are extracted through image analysis of three-dimensional image data, and a crack ratio in the coke cake is determined. A Rankine coefficient corresponding to a determined crack ratio is identified using predetermined correlation between the crack ratio and the Rankine coefficient of coke cake. Here, the crack ratio is a ratio of a number of the crack surfaces with a predetermined vector component larger than a threshold value to a total number of crack surfaces of the coke cake. The predetermined vector component is a vector component that indicates a degree to which a crack plane follows a reference plane defined by an extrusion direction of the coke cake and a furnace height direction of a coke oven.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for evaluating the extrudability of coke cake and a method for producing coke cake based on this evaluation.

Background Art

[0002] In Patent Document 1, based on the amount of crack components generated inside the coke cake obtained by carbonizing the blended coal in a test coke oven and having a direction parallel to the wall surface of the test coke oven, the extrudability of the coke cake in a chamber coke oven is estimated. In this estimation, the relationship between the amount of crack components and the extrusion force when the coke cake is extruded is determined in advance, and the extrudability of the coke cake is estimated based on this relationship. Here, the crack components parallel to the wall surface of the test coke oven are the crack components that extend in the furnace height direction among the cracks formed inside the coke cake, and as the amount of crack components, the area obtained from the length and width of the crack components in the furnace height direction is used.

[0003] In Patent Document 2, the shrinkage amount in the furnace width direction of the coke cake carbonized in a test coke oven and the amount of cracks existing inside the coke cake are determined, and the extrudability of the coke cake is estimated based on this shrinkage amount and the amount of cracks. Here, as the shrinkage amount, the average distance in the furnace width direction of the gap generated between the inner surface of the furnace wall of the test coke oven and the side surface of the coke cake is used. Also, as the amount of cracks, the number of cracks, the area of cracks per unit area, or the width of cracks is used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of the present invention have discovered that the extrudeability of coke cake can be evaluated using a method different from that described in Patent Documents 1 and 2, and have completed the present invention. [Means for solving the problem]

[0006] The first invention of this application is a method for evaluating the extrudeability of coke cake. First, three-dimensional image data is generated by performing X-ray imaging on a coke cake produced by carbonizing raw coal to be evaluated using a test coke oven. Next, crack surfaces located at the boundary between two adjacent coke lumps contained in the coke cake are extracted by image analysis of the three-dimensional image data.

[0007] Next, the crack ratio in the coke cake is determined. The crack ratio is the proportion of crack surfaces in the coke cake where a predetermined vector component is greater than a threshold, relative to the total number of crack surfaces. The predetermined vector component is a vector component that indicates the degree to which the crack surface aligns with a reference plane defined by the extrusion direction of the coke cake and the furnace height direction of the coke oven. Next, using the previously determined correlation between the crack ratio and the Rankine coefficient of the coke cake, the Rankine coefficient corresponding to the determined crack ratio is identified.

[0008] The vector component can be the unit normal vector set for the crack surface, specifically the component perpendicular to the reference plane. The threshold for determining the crack ratio can be set to 0.9. That is, the crack ratio can be determined by counting the number of crack surfaces whose vector component is greater than 0.9.

[0009] The correlation described above is a positive correlation. That is, the higher the crack ratio, the larger the Rankine coefficient. In other words, the lower the crack ratio, the smaller the Rankine coefficient.

[0010] In the method for producing coke cake, which is the second invention of this application, at least one of the brand and blending ratio of raw coal used in producing coke cake is changed based on the Rankine coefficient identified by the method for evaluating the extrudeability of coke cake, which is the first invention of this application. [Effects of the Invention]

[0011] According to the present invention, the extrudeability of coke cake can be evaluated by focusing on the number of crack surfaces in which the vector component is greater than a threshold. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of a coke oven viewed from above, showing the process of extruding the coke cake from the carbonization chamber using an extruder. [Figure 2] This is a flowchart illustrating a method for evaluating the extrusion properties of coke cake. [Figure 3] This figure shows a three-dimensional image (one example) of a coke cake. [Figure 4] This figure shows a three-dimensional image (one example) that only shows cracks. [Figure 5] This is a diagram illustrating the method for defining the crack surface. [Figure 6] This figure shows the correlation between the crack ratio Rrz and the Rankine coefficient K, Rrz-K, for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.5). [Figure 7] This figure shows the correlation between the crack ratio Rrz and the Rankine coefficient K, Rrz-K, for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.7). [Figure 8] This figure shows the correlation between the crack ratio Rrz and the Rankine coefficient K, Rrz-K, for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.8). [Figure 9] This figure shows the correlation between the crack ratio Rrz and the Rankine coefficient K, Rrz-K, for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.9).

Mode for Carrying Out the Invention

[0013] (Coke cake) Coke used in a blast furnace or the like is obtained by crushing a coke cake produced by carbonizing raw coal in a coke oven. The raw coal may be coal of one brand, or may be blended coal in which coals of a plurality of brands are blended at a predetermined blending ratio. The coke oven is composed of a carbonization chamber filled with raw coal and a combustion chamber disposed at a position sandwiching the carbonization chamber, and refractory bricks are disposed on the inner wall surface of the carbonization chamber. In the combustion chamber, heat required for carbonizing the raw coal is generated by burning fuel gas, and in the carbonization chamber, the raw coal is carbonized by receiving heat from the combustion chamber. Generally, the carbonization chamber and the combustion chamber are alternately arranged in a predetermined direction, and constitute one coke oven group.

[0014] A coke cake is produced by carbonizing the raw coal in the carbonization chamber, and the coke cake is discharged from the carbonization chamber by the extruder pushing out the coke cake. The coke cake discharged from the carbonization chamber is crushed and then used as coke charged into the blast furnace. The coke cake is an aggregate of a plurality of coke lumps, and cracks exist between two adjacent coke lumps.

[0015] In the present invention, regarding a plurality of crack surfaces generated in the coke cake, attention is paid to the degree along a plane (hereinafter referred to as "reference plane") defined by the extrusion direction of the coke cake and the furnace height direction of the coke oven, and the extrudability of the coke cake is evaluated. The extrudability of the coke cake depends on the frictional resistance at the contact surface between the coke cake and the carbonization chamber (refractory brick), and the Rankine coefficient K (also referred to as the lateral pressure conversion rate) is used as an index for evaluating this frictional resistance. The Rankine coefficient K is a value obtained by dividing the pressure Pw acting on the inner wall surface of the carbonization chamber by the pressure (extrusion force) Pp when pushing out the coke cake. As the pressure Pw becomes higher than the pressure Pp, the Rankine coefficient K becomes larger, and the extrudability of the coke cake deteriorates.

[0016] The inventors focused on the crack surface along the reference plane as the main cause of deteriorating the extrudability of the coke cake. The point that this crack surface has an adverse effect on the extrudability of the coke cake will be described with reference to FIG. 1. FIG. 1 is a schematic view when the coke oven 10 is viewed from above. A carbonization chamber 12 is provided between two combustion chambers 11, and a state where the coke cake produced by carbonization inside this carbonization chamber 12 is extruded by an extruder 13 is shown.

[0017] As shown in FIG. 1, assume that a crack surface (that is, a crack surface along the reference plane) is formed in the coke cake along the extrusion direction of the coke cake (the vertical direction in FIG. 1) and the furnace height direction of the coke oven 10 (the direction perpendicular to the plane of the paper in FIG. 1). In this case, when an extrusion force F1 in the extrusion direction is applied to the coke cake from the extruder 13, the coke mass is likely to be divided at the crack surface. As a result, a part of the extrusion force F1 is likely to be converted into a pressing force F2 with which the coke cake presses against the inner wall surface of the carbonization chamber. Further, the larger the number of crack surfaces along the reference plane, the higher the ratio of the force converted from the extrusion force F1 to the pressing force F2, which deteriorates the extrudability of the coke cake.

[0018] Therefore, if attention is paid to the degree to which the crack surface is along the reference plane, the extrudability of the coke cake can be evaluated. In the present embodiment, a "rz vector" described later is defined as an index indicating the degree to which the crack surface is along the reference plane. Note that since it is only necessary to grasp the degree to which the crack surface is along the reference plane, it is not limited to the "rz vector" described later.

[0019] (Method for evaluating the extrudability of the coke cake) Hereinafter, a method for evaluating the extrudability of the coke cake will be described with reference to the flowchart shown in FIG. 2.

[0020] In step S101, coke cake is produced by filling a test coke oven with raw coal to be produced and carbonizing it. For example, an electric carbonization furnace can be used as the test coke oven. The conditions for carbonizing the raw coal (such as the heating rate and the maximum temperature reached) are the same as those for carbonizing raw coal in an actual coke oven, and the raw coal used is the same as the raw coal to be evaluated.

[0021] In step S102, a three-dimensional image data of the coke cake produced in step S101 is generated using an X-ray radiography apparatus. Figure 3 shows an example of a three-dimensional image of the coke cake. In Figure 3, the X-axis is the axis extending in the extrusion direction of the coke cake, the Y-axis is the axis extending in the furnace height direction of the carbonization chamber, and the Z-axis is the axis extending in the furnace width direction of the carbonization chamber. The X-axis, Y-axis, and Z-axis are mutually orthogonal axes.

[0022] In step S103, image analysis is performed on the three-dimensional image data generated in step S102 to extract rz vectors for each crack surface, as will be described later. First, as mentioned above, a coke cake has multiple coke lumps and cracks formed between two adjacent coke lumps, so the three-dimensional image showing the coke cake is separated into a three-dimensional image showing only the coke lumps and a three-dimensional image showing only the cracks. Figure 4 is an example of a three-dimensional image showing only cracks extracted from the three-dimensional image of the coke cake shown in Figure 3. The X, Y, and Z axes shown in Figure 4 are the same as in Figure 3.

[0023] Next, multiple crack surfaces are extracted from a three-dimensional image showing only cracks. Here, the method for defining crack surfaces will be explained using Figure 5. Figure 5 is a schematic diagram showing a cross-section of a part of a coke cake, and in Figure 5, three coke lumps A, B, and C are shown. As mentioned above, crack surfaces form the boundaries between two adjacent coke lumps, so crack surface CS1 forming the boundary between coke lumps A and B, crack surface CS2 forming the boundary between coke lumps B and C, and crack surface CS3 forming the boundary between coke lumps A and C are extracted.

[0024] Next, after extracting all the crack surfaces contained in the coke cake, the eigenvectors of these crack surfaces are calculated, and the surface with the same direction vector as the eigenvector with the smallest eigenvalue is designated as the crack surface, and a unit normal vector is set for each crack surface. Then, the unit normal vector is separated into X-axis, Y-axis, and Z-axis components. Here, the X, Y, and Z axes that define each component of the unit normal vector are the same axes (X, Y, Z) shown in Figures 3 and 4, and in this embodiment, the Z-axis component is called the "rz vector". In this way, the rz vector can be obtained for each of the crack surfaces contained in the coke cake.

[0025] Depending on the shape of the crack surface, the unit normal vector may not consist of three axis components, but rather one or two. For example, if the crack surface exists only within a plane (reference plane) aligned with the X and Y axes, the unit normal vector will be only the rz vector, and the rz vector will be "1.0". In this embodiment, since a unit normal vector is set, the closer the rz vector is to 1.0, the closer the crack surface is to the plane (reference plane) aligned with the X and Y axes. In this embodiment, a "unit normal vector" is set for the crack surface, but this is not the only option; for example, a "normal vector" can also be set for the crack surface.

[0026] In step S104, shown in Figure 2, the ratio (hereinafter referred to as the "crack ratio") Rrz (Rrz = 100 × Nrz / Nt) of the number of crack surfaces whose rz vector exceeds the threshold rz_th (hereinafter referred to as the "target crack number Nrz") to the total number of crack surfaces in the coke cake (hereinafter referred to as the "total number of cracks Nt") is calculated. As explained in the processing of step S103, the total number of cracks Nt can be determined by extracting crack surfaces from a three-dimensional image of cracks in the coke cake (Figure 4). Furthermore, since an rz vector is obtained for each crack surface, the target crack number Nrz can be determined by determining whether the rz vector exceeds the threshold rz_th for each crack surface and counting the crack surfaces that show an rz vector exceeding the threshold rz_th.

[0027] In step S105, the Rankine coefficient K is determined based on the crack ratio Rrz obtained in step S104. Here, when determining the Rankine coefficient K, the previously determined correlation relationship Rrz-K between the crack ratio Rrz and the Rankine coefficient K is used. As can be seen from the examples described later, a predetermined correlation relationship Rrz-K holds between the crack ratio Rrz and the Rankine coefficient K. Therefore, by using this correlation relationship Rrz-K, the Rankine coefficient K corresponding to the crack ratio Rrz obtained in step S104 can be determined.

[0028] As shown in the examples described later, the correlation Rrz-K has a positive correlation, and the higher the crack ratio Rrz, the larger the Rankine coefficient K. In other words, the lower the crack ratio Rrz, the smaller the Rankine coefficient K. The method for determining the correlation Rrz-K will be described later.

[0029] In step S105, the extrudeability of the coke cake can be evaluated by determining the Rankine coefficient K. Here, a larger Rankine coefficient K indicates worse extrudeability of the coke cake. In other words, a smaller Rankine coefficient K indicates good extrudeability of the coke cake.

[0030] (How to determine the correlation Rrz-K) When determining the correlation Rrz-K, the crack ratio Rrz is first determined by performing the processing described in steps S101 to S104 shown in Figure 2. The threshold value rz_th used when determining the crack ratio Rrz is set to the same value as the threshold value rz_th used in step S104 shown in Figure 2 when evaluating the extrudeability of the coke cake by the processing shown in Figure 2.

[0031] On the other hand, the Rankine coefficient K is determined for the coke cake whose crack ratio Rrz has been determined. The Rankine coefficient K can be determined by known methods. For example, the Rankine coefficient K can be determined using a cold compression test apparatus. Specifically, load cells for measuring pressure are installed on each wall surface of the cold compression test apparatus, and the Rankine coefficient K can be determined based on the measured values ​​(pressure) of the load cells when a compressive force is applied to the coke cake and the compressive force applied to the coke cake.

[0032] By the method described above, a correlation relationship Rrz-K between the crack ratio Rrz and the Rankine coefficient K can be obtained for a single coke cake. In this correlation relationship Rrz-K, the ratio of the crack ratio Rrz to the Rankine coefficient K is 1:1. Here, as shown in the example described later, the Rankine coefficient K can be changed by changing the packing density when raw coal is packed into the test coke oven. Therefore, by determining the correlation relationship Rrz-K between the crack ratio Rrz and the Rankine coefficient K for each of several packing densities, it is possible to understand the change in the Rankine coefficient K in relation to the change in the crack ratio Rrz.

[0033] As shown in the examples described later, the coefficient of determination R of the correlation Rrz-K depends on the setting of the threshold rz_th. 2 This changes. Therefore, the threshold rz_th can be appropriately determined considering the accuracy when evaluating extrudeability. For example, when producing coke cake using a new coke oven, high accuracy may not be required in evaluating extrudeability, so the coefficient of determination R 2 A low correlation coefficient Rrz-K can be used. On the other hand, when producing coke cake using an aging coke oven that has been in operation for a long time, high accuracy may be required in evaluating extrudeability, so the coefficient of determination R 2 A high correlation Rrz-K can be used.

[0034] According to this embodiment, before manufacturing coke cake in an actual coke oven and extruding the coke cake, the Rankine coefficient K can be determined from the crack ratio Rrz using the correlation relationship Rrz-K, thereby evaluating the extrudeability of the coke cake based on the Rankine coefficient K. If the extrudeability of the coke cake can be evaluated in advance in this way, problems such as those described below can be avoided.

[0035] If the extrudeability of the coke cake deteriorates, the coke cake can clog the carbonization chamber, preventing it from being discharged. To process the coke cake that could not be discharged, the carbonization chamber must be kept open for an extended period, which cools the refractory bricks separating the carbonization chamber and the combustion chamber, potentially damaging them. Furthermore, in aging coke ovens that have been in operation for a long time, the binding force between the refractory bricks tends to decrease, and if the extrudeability of the coke cake deteriorates, the refractory bricks may rupture. These problems can be avoided by evaluating the extrudeability of the coke cake in advance.

[0036] On the other hand, based on the extrudeability of the coke cake evaluated by the process shown in Figure 2, the raw coal can be changed, and the coke cake can be manufactured in an actual coke oven using the changed raw coal.

[0037] For example, if the extrudeability of the coke cake is evaluated as deteriorating, when using only one type of coal as the coking coal, the extrudeability of the coke cake can be re-evaluated by changing the type of coal and performing the process shown in Figure 2. Similarly, when using a blend of coals containing multiple types of coal as the coking coal, the extrudeability of the coke cake can be re-evaluated by changing at least one type of coal or changing the blending ratio and performing the process shown in Figure 2. Then, using the coking coal evaluated as not deteriorating in extrudeability, coke cake can be manufactured in an actual coke oven. [Examples]

[0038] Three different types of coal (A coal, B coal, and C coal) were used. After crushing each type of coal, the proportion of particles with a diameter of 3 mm or less was adjusted to 85% by mass or more. Then, a blend of 45% by mass of A coal, 45% by mass of B coal, and 10% by mass of C coal was placed in an electric carbonization furnace (W400mm x L600mm x H420mm) and carbonized over 18.5 hours to produce coke cake.

[0039] Here, four types of coke cake were produced by varying the amount of blended coal packed into the electric carbonization furnace (in other words, the packing density of the blended coal). The properties of three types of coal (coal A, coal B, and coal C) are shown in Table 1 below, and the packing density of the blended coal is shown in Table 2 below. In Table 2 below, each of the four packing densities is designated as Sample 1 to 4.

[0040] [Table 1]

[0041] In Table 1 above, the volatile content VM was measured in accordance with the provisions of JIS M8812, the total expansion coefficient TD and maximum fluidity MF were measured in accordance with the provisions of JIS M8801, and the average maximum reflectance Ro was measured in accordance with the provisions of JIS M8816.

[0042] [Table 2]

[0043] The manufactured coke cake was cooled to room temperature over one day under a nitrogen atmosphere. After cooling, the coke cake was placed in a transmission X-ray imaging system, and three-dimensional image data of the coke cake (see Figure 1) was obtained by X-ray transmission imaging. The imaging conditions for the transmission X-ray imaging system were as follows: tube voltage of 120kV, tube current of 350mA, slice pitch of 0.5mm, image size of 512×512 pixels, and resolution of 1.132mm / pixel.

[0044] Next, image analysis was performed on the obtained three-dimensional image data to evaluate the state of cracks formed in the coke cake. The known software Avizó was used for the image analysis. In the image analysis, the three-dimensional image of the coke cake was first separated into a three-dimensional image showing only the coke lumps and a three-dimensional image showing only the cracks. Figure 2 shows the three-dimensional image obtained by removing the coke lumps from the three-dimensional image of the coke cake, i.e., a three-dimensional image showing only the cracks present in the coke cake.

[0045] In a three-dimensional image showing only cracks, crack surfaces located at the boundary between two adjacent coke blocks were extracted. By identifying each individual coke block, the crack surfaces could be identified. A unit normal vector was set for each extracted crack surface, and by separating this unit normal vector into its X-axis, Y-axis, and Z-axis components, the rz vector of each crack surface was identified.

[0046] In this example, the range of rz vectors from 0.0 to 1.0 was divided equally into 10 sections, and the number of crack surfaces (hereinafter referred to as "crack count") representing the rz vectors belonging to each section was counted. For example, when the rz vector is 0.15, this rz vector belongs to the section where the rz vector is 0.1 to 0.2, and the crack count in this section is incremented. The results of the crack count are shown in Table 3 below.

[0047] [Table 3]

[0048] For each category shown in Table 3 above, the "0.0~0.1" category indicates a range where the value is greater than or equal to 0.0 and less than or equal to 0.1, and the "0.9~1.0" category indicates a range where the value is greater than 0.9 and less than or equal to 1.0. Other categories also indicate a range where the value is greater than the lower limit and less than or equal to the upper limit. For example, the "0.1~0.2" category indicates a range where the value is greater than 0.1 and less than or equal to 0.2.

[0049] In samples 1-4, the total number of cracks (sum of cracks in all sections) Nt differed from one another, but in all of samples 1-4, the total number of cracks Nt exceeded 1000. According to the results shown in Table 3 above, the higher the packing density, the greater the total number of cracks Nt.

[0050] On the other hand, the Rankine coefficient K was measured for each of the coke cakes from samples 1 to 4 using a cold compression test apparatus. Specifically, load cells were placed on each wall of the cold compression test apparatus to measure pressure, and the Rankine coefficient K was determined based on the measured values ​​(pressure) of the load cells and the compressed pressure applied to the coke cake. The results are shown in Table 4 below.

[0051] [Table 4]

[0052] Next, for each of the coke cake samples from samples 1 to 4, the crack ratio Rrz, which represents the number of target cracks Nrz relative to the total number of cracks Nt, was calculated. Here, the threshold values ​​rz_th were set to 0.5, 0.7, 0.8, and 0.9, respectively. The crack ratios Rrz for each threshold value rz_th are shown in Table 5 below.

[0053] [Table 5]

[0054] Figures 6 to 9 show the relationship between each crack ratio Rrz shown in Table 5 above and the Rankine coefficient K obtained as described above. Figure 6 shows the correlation Rrz-K between the crack ratio Rrz and the Rankine coefficient K for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.5). Figure 7 shows the correlation Rrz-K between the crack ratio Rrz and the Rankine coefficient K for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.7). Figure 8 shows the correlation Rrz-K between the crack ratio Rrz and the Rankine coefficient K for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.8). Figure 9 shows the correlation Rrz-K between the crack ratio Rrz and the Rankine coefficient K for crack surfaces where the rz vector exceeds the threshold rz_th (rz_th=0.9).

[0055] Figures 6 to 9 each show an approximate straight line obtained from the plots of the crack ratio Rrz and the Rankine coefficient K. This approximate straight line is used as the correlation Rrz-K when determining the Rankine coefficient K from the crack ratio Rrz. Figures 6 to 9 each also show the correlation coefficient R of the approximate straight line. 2 It also indicates this.

[0056] As can be seen from Figures 6 to 9, regardless of the threshold rz_th, the Rankine coefficient K tends to increase as the crack ratio Rrz increases. In other words, the Rankine coefficient K tends to decrease as the crack ratio Rrz decreases. If this correlation (in this case, a positive correlation) Rrz-K is determined in advance, the Rankine coefficient K (i.e., the extrudeability of the coke cake) can be determined by calculating the crack ratio Rrz from a three-dimensional image of the coke cake whose extrudeability is to be evaluated.

[0057] On the other hand, as can be seen from Figures 6 to 9, the larger the threshold rz_th, the higher the coefficient of determination R in the correlation between the crack ratio Rrz and the Rankine coefficient K, Rrz-K. 2 The coefficient of determination R increases. In this example, when the threshold rz_th is 0.9, the coefficient of determination R 2Since this is the highest value, setting the threshold rz_th to 0.9 and calculating the crack ratio Rrz can improve the estimation accuracy of the Rankine coefficient K.

[0058] Here, when evaluating the extrudeability of coke cake, the threshold value rz_th can be appropriately determined. As shown in Figure 6, even if the threshold value rz_th is 0.5, it is possible to grasp the approximate correlation relationship Rrz-K between the crack ratio Rrz and the Rankine coefficient K. Therefore, if it is not necessary to strictly evaluate the extrudeability of coke cake, the threshold value rz_th can be set to 0.5. On the other hand, if it is necessary to strictly evaluate the extrudeability of coke cake, the threshold value rz_th can be set to 0.9. [Explanation of Symbols]

[0059] 10 Coke oven 11 Combustion chamber 12 Carbonization Chamber 13 Extruder

Claims

1. A method for evaluating the extrusion properties of coke cake, By performing X-ray imaging on coke cake produced by carbonizing the raw coal to be evaluated using a test coke oven, three-dimensional image data is generated. By analyzing the three-dimensional image data, the crack surfaces located at the boundary between two adjacent coke lumps contained in the coke cake are extracted. The crack ratio is determined as the ratio of the number of crack surfaces in the coke cake to the total number of crack surfaces in the coke cake in which the vector component indicating the degree to which the crack surface aligns with a reference plane defined by the extrusion direction of the coke cake and the furnace height direction of the coke oven is greater than a threshold. A method for evaluating the extrudeability of a coke cake, characterized by using a predetermined correlation between the crack ratio and the Rankine coefficient of the coke cake to identify the Rankine coefficient corresponding to the determined crack ratio.

2. The method for evaluating the extrudeability of a coke cake according to claim 1, characterized in that the vector component is a vector component of the unit normal vector set with respect to the crack surface, in a direction perpendicular to the reference plane.

3. The method for evaluating the extrudeability of coke cake according to claim 2, characterized in that the threshold value is 0.

9.

4. The method for evaluating the extrudeability of coke cake according to claim 1, characterized in that the correlation is positive.

5. A method for producing coke cake, characterized by changing at least one of the brand and blending ratio of raw coal used when producing coke cake, based on the Rankine coefficient identified by the method for evaluating the extrudeability of coke cake according to any one of claims 1 to 4.

Images