Coal crushing method and crushing equipment

Abstract

To quickly and accurately change, when distributing coal by rigidity range into a plurality of lines of compounding vessel lines A for crushing, a crushing condition of coal according to change of a coal blending plan.SOLUTION: A crushing method of coal comprises the steps of: obtaining, when a product of rigidity of coal crushed in each compounding vessel line A and transported coal amount is a throughput rate p, a slope of a regression line r representing a relation between a crushing strength of coal obtained in advance in each compounding vessel line A and a coal grain size after crushing, and obtaining an approximation curve a that draws a relation between the slop and the throughput rate p as a coordinate; obtaining, when the throughput rate p is changed due to change of a blending plan, 'slope em of the regression line' corresponding to a throughput rate pm after change by using the approximation curve a, and measuring, even after changing the blending plan, the coal grain size after crushing while continuously crushing the coal by the crushing strength that is a value before changing the blending plan for a prescribed time to obtain a difference Δd between the measured grain size and a target grain size; and obtaining a change amount Δf with respect to the crushing strength f before changing the blending plan based on 'the slope em of the regression line' and 'the difference Δd between the grain sizes' so as to crush the coal by the crushing strength f+Δf.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coal pulverization technology that can appropriately adjust and manage the pulverized particle size of coal in response to changes in the coal blending plan in a coke manufacturing process or the like. [Background technology]

[0002] Coke used in blast furnaces must be high-strength and of uniform quality (particle size and strength) to ensure good ventilation inside the furnace. To produce high-strength, uniform-quality coke, it is necessary to increase the bulk density of the coal charged into the coke oven so that strong contact occurs between the coal particles when the coal is heated and carbonized in the coke oven. To achieve this, it is important to optimize the particle size of the coal charged into the coke oven. Coarse coal particles with large particle sizes undergo carbonization in a coke oven due to differences in shrinkage rates between adjacent coal particles, resulting in cracks at the contact interface and reduced coke strength. Meanwhile, fine coal particles with small particle sizes become airborne when charged into the coke oven, reducing bulk density. Therefore, to produce high-strength, uniform-quality coke, it is necessary to select grinding conditions to achieve the target particle size when grinding the coal in a grinder and reduce particle size variation.

[0003] The particle size of coal crushed by a pulverizer varies depending on factors such as the gap between the pulverizer's hammer and the repulsion plate (grinding plate), the current value of the pulverizer's motor, and the rotation speed of the pulverizer's hammer.A common method is to adjust these factors to match the coal particle size after crushing to the target particle size. Conventional techniques for crushing coal include a method of measuring the particle size of the coal after crushing and adjusting the gap between the hammer and the repulsion plate of the crusher (Patent Document 1), a method of adjusting the rotation speed of the hammer of the crusher (Patent Document 2), and a method of adjusting the current value of the crusher according to the particle size and moisture content of the coal before crushing, using an equation that shows the relationship between the coal crushing energy and the particle size distribution before and after crushing (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-319663 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-16983 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-159196 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the methods described in Patent Documents 1 and 2, which change the grinding conditions based on the measured particle size of the coal after grinding, it is difficult to adjust the grinding particle size of the coal to a target particle size range when the coal blending plan is changed. In other words, in coke production, the coal blending plan is frequently changed to ensure coke productivity and quality, and each time the blending ratio of coals with different hardness (e.g., HGI) changes depending on the brand. Therefore, simply changing the grinding conditions based on the coal particle size after grinding, as described in Patent Documents 1 and 2, makes it difficult to adjust the grinding particle size of the coal to a target particle size range when the coal blending plan is changed. Therefore, each time the coal blending plan is changed, it is necessary to perform grinding multiple times under different grinding conditions, measure the grinding particle size, and determine the relationship between the grinding conditions and the grinding particle size. This creates a problem in that the coal grinding conditions cannot be changed quickly and accurately. Furthermore, even with the method of adjusting the current value of the pulverizer according to the particle size and moisture content of the coal before pulverization as in Patent Document 3, it is difficult to adjust the particle size of the pulverized coal to a target particle size range when the coal blending plan is changed. Furthermore, with the method of Patent Document 3, it is not possible to know the particle size of the coal after pulverization, and therefore it is not possible to adjust the pulverization conditions based on the particle size of the coal after pulverization.

[0006] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a coal pulverization method and pulverization equipment that can determine the particle size of coal after pulverization and adjust the pulverization conditions, and that can quickly and accurately change the coal pulverization conditions in response to changes in the coal blending plan, thereby appropriately adjusting and managing the pulverized coal particle size. [Means for solving the problem]

[0007] The gist of the present invention for solving the above problems is as follows. [1] A coal pulverization facility having a plurality of blending vessel lines (A) equipped with one or more blending vessels (1) for storing coal, a pulverizer (2) for pulverizing the coal discharged from the blending vessels (1), and a particle size meter (3) for measuring the particle size of the coal pulverized by the pulverizer (2), wherein the coal is sorted into the plurality of blending vessel lines (A) according to hardness range and pulverized; and in each blending vessel line (A), a relationship between the crushing strength of the coal by the pulverizer (2) and the particle size of the coal after crushing is determined in advance, and based on this relationship, the method pulverizes the coal while adjusting the crushing strength of the coal by the pulverizer (2) so that the particle size of the coal after crushing measured by the particle size meter (3) becomes a target particle size, When the product of the hardness of the coal pulverized in each blending tank line (A) and the coal feed rate is defined as the processing rate p, The relationship between the crushing strength of the coal by the crusher (2) in each blending vessel line (A) and the particle size of the coal after crushing is linearly regressed in advance to determine the slope of the regression line r, and an equation for an approximation curve a drawn using the relationship between the slope of the regression line r and the throughput p as a coordinate is determined; Any one or more blending tank lines (A m When the processing amount p is changed due to a change in the coal blending plan in the above-mentioned method, a change amount Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated by the following (i) to (iii), and thereafter the coal is crushed at the crushing strength (f + Δf). (i) Processing volume p after change due to change in coal blending plan m Applying this to the equation for the fitted curve a, the modified processing volume p m The slope of the regression line em " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder (2) is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, the particle size of the coal after grinding is measured by the particle size meter (3), and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The slope of the regression line e obtained in (i) above m " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the processing amount p after the change. m The amount of change in crushing strength Δf relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e m …(1)

[0008] [2] The method for crushing coal according to [1] above, wherein the crusher (2) is a hammer crusher, and the crushing strength of the coal by the crusher (2) is the number of hammer rotations of the crusher (2). [3] The method for crushing coal according to the above [1] or [2], wherein the hardness of the coal is HGI (Hardgrove Grindability Index). [4] In any one of the pulverization methods [1] to [3] above, when each blending vessel line (A) has a plurality of blending vessels (1), coals of different hardness are stored in these plurality of blending vessels (1), and coals discharged from the plurality of blending vessels (1) are pulverized, the processing amount p is the sum of the products of the amounts of coal discharged from each blending vessel (1) and the hardness of the coal. [5] In any one of the above-mentioned [1] to [4] pulverization methods, the granulometer (3) captures an image of the surface of the coal bed that has been pulverized by the pulverizer (2) and is being transported by the transport conveyor, and measures the proportion of coarse particles in the coal based on the image.

[0009] [6] In any of the crushing methods [1] to [5] above, the processing amount p after the change mWhen coal is crushed at a crushing strength (f+Δf) set according to the above, if the coal particle size measured by a particle size meter (3) after crushing becomes larger than a target particle size over time, the crushing method in the crusher (2) is changed. [7] The method for crushing coal according to [6] above, wherein the crusher (2) is a hammer crusher, and the change in the crushing method in the crusher (2) is one or more of the following (i) and (ii): (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2). [8] The method for crushing coal according to [7] above, characterized in that the change in the crushing method in the crusher (2) is carried out with priority given to the following (i), and if the coal particle size measured by the particle size meter (3) after crushing is still larger than the target particle size after the change in the crushing method, the method for crushing coal according to [7] above is carried out with priority given to the following (ii). (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2).

[0010] [9] A coal crushing facility comprising: a plurality of blending vessel lines (A) each including one or more blending vessels (1) for storing coal, a crusher (2) for crushing the coal discharged from the blending vessels (1), a controller (7) for adjusting the crushing strength of the crusher (2), and a particle size meter (3) for measuring the particle size of the coal crushed by the crusher (2); and an arithmetic and control device (6) for controlling the crushing strength of the coal in the crusher (2) via the controller (7) based on a predetermined relationship between the crushing strength of the coal by the crusher (2) in each blending vessel line (A) and the particle size of the coal after crushing and the measured particle size meter (3) so that the particle size of the coal after crushing becomes a target particle size; wherein the coal is crushed by distributing the coal according to hardness ranges among the plurality of blending vessel lines (A), The calculation control device (6) calculates a processing amount p by linearly regressing the relationship between the crushing strength of the coal by the crusher (2) in each blending tank line (A) and the particle size of the coal after crushing, and determines the slope of the regression line r. ... m When a processing amount p is changed due to a change in the coal blending plan, a change amount Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated by the following (i) to (iii), and thereafter the crushing strength of the crusher (2) is controlled via a controller (7) so that the coal is crushed at the crushing strength (f + Δf). (i) Processing volume p after change due to change in coal blending plan m Applying this to the equation for the fitted curve a, the modified processing volume p m The slope of the regression line e m " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder (2) is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, the particle size of the coal after grinding is measured by the particle size meter (3), and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The slope of the regression line e obtained in (i) above m " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the processing amount p after the change. m The amount of change in crushing strength Δf relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e m …(1)

[0011]

[10] The coal crushing facility according to [9] above, wherein the crusher (2) is a hammer crusher, and the crushing strength of the coal by the crusher (2) is the hammer rotation speed of the crusher (2).

[11] The coal crushing equipment according to [9] or

[10] above, wherein the hardness of the coal is HGI (Hardgrove Grindability Index).

[12] In the crushing equipment of any one of [9] to

[11] above, when each blending tank line (A) has a plurality of blending tanks (1), coals of different hardness are stored in these plurality of blending tanks (1), and coals discharged from the plurality of blending tanks (1) are crushed, the processing amount p is the sum of the product of the amount of coal discharged from each blending tank (1) and the hardness of the coal.

[13] In the crushing equipment of any one of the above items [9] to

[12] , the particle size meter (3) takes an image of the surface of the coal bed that has been crushed by the crusher (2) and is being transported by the conveyor, and measures the proportion of coarse particles in the coal based on the image.

[0012]

[14] In any of the crushing equipments [9] to

[13] above, the arithmetic and control device (6) m When coal is crushed at a crushing strength (f+Δf) set according to the above, if the particle size of the crushed coal measured by the particle size meter (3) becomes larger than the target particle size over time, the equipment determines that the crushed particle size is inappropriate due to a factor in the crusher (2) itself, and outputs the determination result or an instruction to change the crushing method of the crusher (2) based on the determination result.

[15] In the crushing facility of

[14] above, the crusher (2) is a hammer crusher, and the crushing method of the changeable crusher (2) is one or more of the following (i) and (ii). (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2). [Effects of the Invention]

[0013] According to the present invention, it is possible to adjust the grinding conditions by grasping the particle size of the crushed coal, and also to quickly and accurately change the coal grinding conditions in response to changes in the coal blending plan, thereby appropriately adjusting and managing the crushed particle size of the coal, thereby enabling the production of high-strength coke of uniform quality. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram showing a coal pulverizing facility for producing coke used in carrying out the method of the present invention, and an embodiment of the method of the present invention using the coal pulverizing facility. [Figure 2] A graph showing the relationship between the crushing strength of coal by a crusher and the particle size of the coal after crushing. [Figure 3] FIG. 2 is an explanatory diagram showing a method for calculating the processing amounts p1 to p3 in the blending vessel lines A1 to A3 in the embodiment of FIG. 1. [Figure 4] In the embodiment of FIG. 1, a diagram showing regression lines r1 to r3 of slopes (absolute values ​​of slopes) e1 to e3 that define the "relationship between the number of hammer revolutions of the pulverizer and the particle size of coal after pulverization" previously determined for each of the blending vessel lines A1 to A3. [Figure 5] Graph showing an approximation curve a plotted as a coordinate representing the relationship between the throughputs p1 to p3 in the blending vessel lines A1 to A3 in the embodiment of FIG. 1 and the slopes (absolute values ​​of the slopes) e1 to e3 of the regression lines in FIG. [Figure 6] FIG. 2 is an explanatory diagram schematically showing a method for calculating the post-change throughputs pm1 to pm3 in the blending vessel lines A1 to A3 when the throughput p is changed due to a change in the coal blending plan in the embodiment of FIG. 1. [Figure 7] 1. FIG. 6 is a diagram showing a schematic diagram of a case where the changed throughputs pm1 to pm3 shown in FIG. 6 are applied to the approximation curve a shown in FIG. 5 to find the "slope of the regression line (absolute value of the slope) em1 to em3" corresponding to the changed throughputs pm1 to pm3 in the embodiment of FIG. [Figure 8] FIG. 2 is a diagram (schematic diagram) for explaining that, in the embodiment of FIG. 1, when the processing amount p is changed due to a change in the coal blending plan, the change amount ΔN of the hammer rotation speed relative to the hammer rotation speed N before the change in the coal blending plan is calculated according to (i) to (iii) defined by the present invention. [Figure 9] FIG. 1 is an explanatory diagram schematically illustrating an embodiment of a particle size meter used in the present invention and its usage situation. [Figure 10] FIG. 10 is an explanatory diagram showing the processing flow of the particle size calculation device when measuring the coal coarse particle ratio (coal particle size) using the particle size meter of FIG. [Figure 11] In the examples, the regression lines r1 to r3, which define the relationship between the hammer rotation speed of the pulverizer and the particle size of the coal after pulverization, are determined in advance for each blending vessel line A1 to A3, and have absolute values ​​of slope of 0.007, 0.0135, and 0.0198, respectively. [Figure 12] 12 is a graph showing an approximate curve a plotted using the relationship between the throughput of the blending vessel lines A1 to A3 and the absolute value of the slope of the regression line in FIG. 11 as a coordinate in the examples. [Figure 13] 12. In the example, the processing amounts pm1 to pm3 changed due to a change in the coal blending plan are applied to the approximation curve a shown in FIG. 12, and the "slope of the regression line (absolute value of the slope) em1 to em3" corresponding to the changed processing amounts pm1 to pm3 are calculated. DETAILED DESCRIPTION OF THE INVENTION

[0015] A coal pulverization facility for producing coke used in the practice of the present invention has multiple blending vessel lines A (n blending vessel lines A1 to An) as a coal pulverization system, and in the present invention, coal is sorted into the multiple blending vessel lines A according to hardness range and pulverized. That is, coals of different hardness ranges are pulverized in each blending vessel line A. Since HGI (Hardgrove Grindability Index) is generally used to measure coal hardness, the following describes the case where coals of different HGI ranges are pulverized in each blending vessel line A. 1 is a schematic diagram showing a coal pulverization facility for coke production used in the practice of the present invention, and one embodiment of the method of the present invention using this coal pulverization facility. In this embodiment, coal is divided into three groups based on HGI (large HGI, medium HGI, small HGI), and the coals in these three groups with different HGI ranges are sorted into three blending vessel lines A1 to A3, and pulverized in each line.

[0016] Below, an overview of the coal pulverization method and equipment that form the basis of the present invention will be described with reference to Figure 1. Each blending vessel line A (A1 to A3) includes a plurality of blending vessels 1 for storing coal, pulverizers 2 (2a to 2c) that pulverize the coal discharged from these blending vessels 1, and particle size meters 3 (3a to 3c) that measure the particle size of the coal pulverized by these pulverizers 2. Coal is stored in a coal yard by brand, and the coal to be used from the stored coal is transported by brand on a transfer conveyor (belt conveyor) and stored in a blending tank 1. As described above, in the present invention, coal is sorted into multiple blending tank lines A according to HGI range and crushed, but typically, different brands of coal (naturally, these different brands of coal also have different HGIs) are stored in multiple blending tanks 1 of each blending tank line A.

[0017] Once a blending plan (plan related to blending ratios) for the coal to be charged into the coke oven has been decided, a predetermined amount (predetermined amount per unit time) of a predetermined brand of coal is extracted from the multiple blending tanks 1 of each blending tank line A in accordance with this blending plan, and is transported by a transfer conveyor 4 (belt conveyor) to a pulverizer 2, where it is pulverized to a predetermined particle size. The coal pulverized by the pulverizer 2 is then transported by a transfer conveyor 5 (belt conveyor) to the coke oven (its inlet facility), and the coal particle size of the coal being transported by this transfer conveyor 5 is continuously measured by a particle size meter 3. The coal pulverized in the multiple rows of blending tank lines A is then joined and mixed, and subjected to any necessary processing (such as humidity control) before being charged into the coke oven.

[0018] While the coal particle size measured by the particle size meter 3 and its measurement method are not particularly limited, the coal particle size measured by the particle size meter 3 can be the proportion of coarse particles in the coal (e.g., the proportion of coarse particles with a particle size of 6 mm or more) rather than the overall particle size distribution. In other words, this coarse particle proportion can represent the particle size distribution of the coal and, as described below, has a high correlation with the crushing strength of the crusher 2. Furthermore, as described above, coarse particles in coal reduce coke strength, so measuring the coarse particle proportion and managing the particle size is also meaningful for ensuring coke strength. The coarse particle proportion of coal can be measured online easily and with high accuracy by capturing an image of the coal layer surface being transported by the conveyor 5 using a CCD camera or the like, processing the image, and calculating the particle size, as described below. The method for measuring the coarse particle proportion of coal will be described in detail later. When measuring the coarse particle proportion of coal using the particle size meter 3, a lower particle size limit (e.g., 6 mm) is typically set in the particle size range of 6 mm to 50 mm, and particles with particle sizes above this limit are considered coarse particles, and their proportion (relative to the total amount of coal) is calculated. The reason for setting the lower limit of the particle size of the coarse particles in the above range is that the particle size can be measured advantageously by a camera-type measuring means, and the proportion of coarse particles is small, so the frequency of coarse particles stacking on each other is low. If the lower limit of the particle size of the coarse particles is set to less than 6 mm, it will be necessary to use a laser diffraction method or the like for measurement. The type of the crusher 2 is not particularly limited, and for example, a hammer crusher, an impact crusher, a roll crusher, etc. can be used, but a hammer crusher is often used. In the following explanation, the case where a hammer crusher is used will be mainly described as an example.

[0019] In the present invention, the basic form of coal pulverization is as follows. In each blending vessel line A (A1-A3), the relationship (correlation) between the pulverization strength when pulverizing coal in pulverizer 2 and the coal particle size after pulverization (preferably the coarse particle ratio; the same applies below)—i.e., the relationship as schematically shown in FIG. 2 —is determined in advance based on the results of a test or actual operation conducted in advance. Then, based on this relationship, the coal is pulverized while adjusting (controlling) the pulverization strength of pulverizer 2 with controller 7 so that the coal particle size measured by particle size meter 3 matches the target particle size (the target particle size after pulverization; the same applies below). Here, the relationship (correlation) between the pulverization strength of pulverizer 2 and the coal particle size after pulverization varies depending on the HGI of the coal. As shown in FIG. 1 , in the present invention, coals with different HGI ranges are pulverized separately in multiple blending vessel lines A, and therefore the relationship between the pulverization strength of pulverizer 2 and the coal particle size after pulverization is determined in advance for each blending vessel line A.

[0020] The crushing strength when crushing coal in the crusher 2 is, for example, the hammer rotation speed in the case of a hammer crusher. Therefore, when the crushing strength is the hammer rotation speed, the relationship between the hammer rotation speed of the crusher 2 in each blending vessel line A and the particle size of the crushed coal is determined in advance, and based on this relationship, the hammer rotation speed of the crusher 2 is adjusted (controlled) as described above by the controller 7. Specifically, the calculation and control device 6 compares the coal particle size measured by the particle size meter 3 with the target particle size, and based on the previously determined relationship described above, determines the hammer rotation speed required to achieve the target particle size.The controller 7 then rotates the hammer of the pulverizer 2 at that hammer rotation speed to pulverize the coal. In addition, examples of the crushing strength in the case of other types of crushers include the roll rotation speed in the case of a roll crusher, and the rotor rotation speed in the case of an impact crusher.

[0021] In the present invention, in the coal pulverization process performed as described above, if the coal blending plan is changed in any one or more blending vessel lines Am, the pulverization conditions (pulverization intensity) are changed as follows to pulverize the coal. Here, the throughput p is defined as the product of the hardness (HGI) of the coal to be pulverized and the coal feed amount in each blending tank line A. Therefore, when each blending tank line A has multiple blending tanks 1, and coals of different HGI are stored in these multiple blending tanks 1 and these are fed to the transfer conveyor 4, the throughput p is the sum of the product of the coal feed amount from each blending tank 1 and the HGI of that coal (the sum of the values ​​calculated for each blending tank 1 (= coal feed amount × coal HGI)).

[0022] In the present invention, the relationship (correlation) between the crushing strength of the coal by the crusher 2 in each blending vessel line A and the particle size of the coal after crushing is linearly regressed to determine the slope of the regression line r, and further determine the equation of an approximation curve a plotted using the relationship between the slope of the regression line r and the throughput p as coordinates. Then, when the throughput p is changed due to a change in the coal blending plan in any one or more blending vessel lines Am, the amount of change Δf in crushing strength relative to the crushing strength f before the change in the coal blending plan is determined using the following (i) to (iii), and thereafter the coal is crushed at that crushing strength (f + Δf). (i) Processing volume p after change due to change in coal blending plan m Applying this to the equation for the fitted curve a, the modified processing volume p m The slope of the regression line e m " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder 2 is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, the particle size of the coal after grinding is measured by the particle size meter 3, and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The slope of the regression line e obtained in (i) above m " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the processing amount p after the change. m The amount of change in crushing strength Δf relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e m …(1) Here, the "certain period of time" in (ii) above may be any period of time until the particle size of the coal after pulverization can be stably measured, and may be set appropriately depending on the situation. The above-described change of the pulverization conditions according to the present invention is usually repeated every time the coal blending plan is changed.

[0023] In addition, the processing volume after the change p m When coal is crushed at a crushing strength (f+Δf) set according to the above, if the "coal particle size after crushing" measured by the particle size meter 3 becomes larger than the target particle size over time, it can be said that the crushed particle size is inappropriate due to factors within the crusher 2 itself (for example, wear of the hammer).For this reason, in this case, it is determined that the previously determined "relationship between the coal crushing strength by the crusher 2 and the coal particle size after crushing" does not hold, and action is taken to change the coal crushing method in the crusher 2. Here, "the coal particle size after crushing becomes larger than the target particle size over time" means that the coal particle size after crushing remains larger than the target particle size for a certain period of time. For example, this could be the case where the coal particle size after crushing remains larger than the target particle size for a period of time longer than the time it takes to break down the coal in the yard pile. Furthermore, changing the coal crushing method could, for example, be changing the rotation direction of the hammers of crusher 2, or changing the gap between the hammers of crusher 2 and the repulsion plate, if crusher 2 is a hammer crusher.

[0024] The embodiment of FIG. 1 will be described in more detail below, but here, the case where the crushing strength of coal is "the number of hammer revolutions of the crusher 2" will be described. In carrying out the present invention, the "relationship between the hammer rotation speed of the pulverizer 2 and the coal particle size after pulverization" (i.e., the "relationship between the hammer rotation speed of the pulverizer 2 and the coal particle size after pulverization" before the coal blending plan, as described below, is changed) is determined in advance for each blending vessel line A1-A3, where coal is sorted by HGI range and pulverized. The target particle size after pulverization is determined for each blending vessel line A, and the arithmetic and control device 6 calculates the hammer rotation speed N0 corresponding to the target particle size based on the previously determined "relationship between the hammer rotation speed of the pulverizer 2 and the coal particle size after pulverization." This hammer rotation speed N0 differs for each blending vessel line A1-A3. The arithmetic and control device 6 controls the pulverizer 2 via the controller 7 to pulverize the coal at the hammer rotation speed N0. The pulverized coal particle size is measured by the particle size meter 3. The arithmetic and control device 6 compares the measured coal particle size with the target particle size, and if there is a difference, calculates the amount of change in the hammer rotation speed to match the target particle size. Then, the controller 7 is given a new hammer rotation speed N1 of the pulverizer 2 (this hammer rotation speed N1 differs for each blending vessel line A1 to A3), and the pulverizer 2 is controlled to pulverize the coal at this hammer rotation speed N1.

[0025] In the coal pulverization process performed as described above, when the coal blending plan for the blending vessel lines A1 to A3 is changed, the pulverization conditions (hammer rotation speed of pulverizer 2) are changed as follows to pulverize the coal. First, the throughput p (throughputs p1 to p3) in each blending vessel line A1 to A3 is the product of the hardness (HGI) of the coal to be pulverized and the coal feed rate, and the calculation method is shown schematically in FIG. 3. For example, assume that blending vessel line A1 pulverizes coal with an HGI of 80 or greater but less than 100, blending vessel line A2 pulverizes coal with an HGI of 60 or greater but less than 80, and blending vessel line A3 pulverizes coal with an HGI of 40 or greater but less than 60. In this case, for example, if the four blending vessels 1 in blending vessel line A1 store coals with HGIs of 82, 96, 92, and 86, respectively, and the coal feed rates from each blending vessel 1 are x1 to x4 (t / h), then the throughput p1 is calculated as p1 = 82*x1 + 96*x2 + 92*x3 + 86*x4. Here, for example, p1 = 90. Furthermore, for example, if the four blending tanks 1 of the blending tank line A2 store coals of HGI: 62, HGI: 76, HGI: 72, and HGI: 66, respectively, and the coal feed rates from each blending tank 1 are y1 to y4 (t / h), then the throughput p2 is p2 = 62 * y1 + 76 * y2 + 72 * y3 + 66 * y4. Here, for example, p2 = 70. Also, for example, if the four blending tanks 1 of the blending tank line A3 store coals of HGI: 42, HGI: 56, HGI: 52, and HGI: 46, respectively, and the coal feed rates from each blending tank 1 are z1 to z4 (t / h), then the throughput p3 is p3 = 42 * z1 + 56 * z2 + 52 * z3 + 46 * z4. Here, for example, p3 = 50.

[0026] The "relationship between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization" previously determined for each blending vessel line A1-A3 (i.e., the "relationship between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization" before the change in the coal blending plan) is then regressed onto a straight line as shown schematically in Figures 4(a)-(c), and the slopes (absolute values ​​of the slope) e1=1, e2=2, and e3=3 of these regression lines r1-r3 are determined. Furthermore, as shown schematically in Figure 5, the equation of an approximation curve a is determined, which is plotted using the relationship between the slopes (absolute values ​​of the slope) e1=1, e2=2, and e3=3 and the throughputs p1=90, p3=70, and p3=50 as coordinates. This approximation curve represents the ease of crushing the coal.

[0027] Figure 6 shows the processing amount p(p m1 ~p m3 ) is calculated. In this example, the coal feed rate from each blending tank 1 of the blending tank lines A1 to A3 is changed, and the processing rate p of the blending tank lines A1 to A3 is changed. Here, in the blending tank line A1, if the coal feed rate from each blending tank 1 is changed to x5 to x8 (t / h), the processing rate p is calculated by p m1 =82*x5+96*x6+92*x7+86*x8. Here, for example, p m1 = 95. In addition, in the blending tank line A2, if the coal sending rate from each blending tank 1 is changed to y5 to y8 (t / h), the processing rate p will be p m2 =62*y5+76*y6+72*y7+66*y8. Here, for example, p m2 = 80. In addition, in the blending tank line A3, if the coal sending rate from each blending tank 1 is changed to z5 to z8 (t / h), the processing rate p will be p m3 =42*z5+56*z6+52*z7+46*z8. Here, for example, p m3 =45.

[0028] Then, the arithmetic and control device 6 calculates the changed throughput p m1 ~p m3 The hammer rotation speed of the pulverizer 2 (= crushing strength of the coal by the pulverizer 2) corresponding to the above is calculated. Specifically, the change amount ΔN of the hammer rotation speed with respect to the hammer rotation speed N of the pulverizer 2 before the change in the coal blending plan (the change amount Δf of the crushing strength with respect to the crushing strength f before the change in the coal blending plan) is calculated using the following (i) to (iii). (i) As shown in FIG. 7, the processing volume p m1 ~p m3 Applying this to the equation for the approximate curve a in Figure 5, the processing volume p m1 ~p m3 The slope of the regression line (absolute value of the slope) e m In the example of Figure 7, the processing amount p m1 = 95, the corresponding slope of the regression line (absolute value of the slope) e m1=0.75 is the processing volume p after the change in the blending tank line A2 m2 = 80, the corresponding slope of the regression line (absolute value of the slope) e m2 = 2.5 is the processing volume p after the change in the blending tank line A3 m3 = 45, the corresponding slope of the regression line (absolute value of the slope) e m3 =3.25 are obtained respectively.

[0029] (ii) The slope of the regression line (absolute value of the slope) e m In addition to calculating "," even after the coal blending plan is changed, the grinding of coal by the grinder 2 is continued for a certain period of time at the hammer rotation speed N (= grinding intensity) that was maintained before the change in the coal blending plan, and the particle size of the coal after grinding is measured by the particle size meter 3 in each blending tank line A, and the difference Δd between this measured particle size and the target particle size is calculated. Figure 8(A) shows a schematic diagram of the coal particle size measured in a certain blending tank line A and the difference Δd between this measured particle size and the target particle size. (iii) The slope of the regression line (absolute value of the slope) e obtained in (i) above m " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1a) is used to calculate the processing amount p after the change. m The change amount ΔN in the hammer rotation speed relative to the hammer rotation speed N before the change in the coal blending plan is calculated, corresponding to the above. Figure 8(B) shows the change amount ΔN in the hammer rotation speed calculated for a certain blending vessel line A. ΔN=Δd / e m …(1a)

[0030] Here, the reason why the "coal particle size after crushing (measured value)" measured while continuing crushing at the hammer rotation speed N before the change in coal blending plan is used to determine the change in hammer rotation speed ΔN (change in crushing strength Δf) as described above is as follows: Coal within a relatively narrow HGI range is allocated to each of the blending tank lines A1 to A3, and changes to the coal blending plan are made within that range, so the range of change in processing volume is not that great. For this reason, it is thought that using the "coal particle size after crushing (measured value)" measured while continuing crushing at the hammer rotation speed before the change in coal blending plan will not result in a significant error.

[0031] In this way, the arithmetic and control device 6 calculates the changed throughput p m1 (=95), p m2 (=80), p m3 The change amount ΔN in the hammer rotation speed relative to the hammer rotation speed N before the change in the coal blending plan, corresponding to (=45), is calculated. Figure 8(C) shows a schematic example of a calculation of the change amount ΔN in the hammer rotation speed for coal in the blending tank line A1. In this example, the measured particle size is 13% compared to the target particle size of 8%, so the difference Δd between the two particle sizes is 5%. The slope of the regression line (absolute value of the slope) e m1 " is 0.75, the change amount ΔN of the hammer rotation speed is as follows: 0.75=5 / ΔN ΔN=5 / 0.75=6.6

[0032] Therefore, after the change amount ΔN in the hammer rotation speed is determined as described above, the coal is pulverized at the hammer rotation speed (N+ΔN) (= pulverization strength (f+Δf)) relative to the hammer rotation speed N before the change in the coal blending plan. That is, the calculation and control device 6 provides the hammer rotation speed (N+ΔN) to the controller 7, and controls the pulverizer 2 so that the coal is pulverized at this hammer rotation speed (N+ΔN). In other words, the coal is pulverized using the hammer rotation speed (N+ΔN) as the initial setting value after the change in the coal blending plan. Even after the coal blending plan is changed, the particle size of the coal after pulverization by the pulverizer 2 is naturally measured by the particle size meter 3. The calculation and control device 6 compares this measured coal particle size with the target particle size, and if there is a difference, calculates the amount of change in the hammer rotation speed to make them match. The controller 7 then provides the amount of hammer change to be changed for the pulverizer 2 (this hammer change amount differs for each blending vessel line A1 to A3), and controls the pulverizer 2 so that the coal is pulverized by this hammer change amount.

[0033] In addition, as described above, the processing volume p m1 ~p m3 When coal is crushed at the hammer rotation speed (N+ΔN) set according to the above, or at a further adjusted hammer rotation speed, if the crushed coal particle size measured by the particle size meter 3 is larger than the target particle size over time (i.e., continuously for a certain period of time), it can be said that the crushed particle size is inappropriate due to a factor within the crusher 2 itself (e.g., wear of the hammer).For this reason, in this case, it is determined that the "relationship between the hammer rotation speed of the crusher 2 and the crushed coal particle size" does not hold, and action is taken to change the coal crushing method in the crusher 2. Therefore, when the particle size of the crushed coal measured by the particle size meter 3 as described above is larger than the target particle size, the arithmetic and control device 6 determines that the crushed particle size is inappropriate due to a factor within the crusher 2 itself, and outputs the determination result or an instruction based on the determination result to change the crushing method of the crusher 2, and displays this on the monitor 8, etc. Based on this, the crushing method of the crusher 2 is changed. Here, the "coal crushing method in a crusher" to be changed refers to the mechanical settings and operating methods for crushing coal, and in the case of a hammer crusher, examples include (i) the rotation direction of the hammer, (ii) the gap between the hammer and the repulsion plate (grinding plate), etc., and one or more of these are changed. In addition, in the case of other types of crushers, examples include the gap between the rolls in the case of a roll crusher, and the gap between the striking plate and the collision plate in the case of an impact crusher.

[0034] Regarding the "gap between the hammer and the repulsion plate," the relationship (correlation) between the particle size of the coal after crushing and the "gap between the hammer and the repulsion plate" is determined in advance under crushing conditions where the hammer rotation speed of the crusher 2 is constant, and the initial setting of the gap between the hammer and the repulsion plate is made based on this relationship, and the above (ii) changes this gap between the hammer and the repulsion plate. The same applies to the gap between the rolls in the case of a roll crusher, and the gap between the striking plate and the collision plate in the case of an impact crusher. Furthermore, when changing the crushing method of a hammer crusher between (i) and (ii) above, it is preferable to first give priority to (i), and then, if the particle size of the crushed coal measured by the particle size meter 3 is still larger than the target particle size even after changing the crushing method, to carry out (ii) above. This is because, as a form of changing the crushing method of the crusher 2, (i) above is simpler than (ii) above and has the advantage of being able to be dealt with quickly, but even among incompatible crushed particle sizes caused by wear of the hammers of the crusher 2, etc., relatively minor wear etc. can often be resolved by taking the measure of (i) above.

[0035] A pulverization facility for carrying out the above-described coal pulverization method of the present invention has the following configuration. Specifically, the pulverization facility includes one or more blending vessels 1 for storing coal, a pulverizer 2 for pulverizing the coal discharged from the blending vessel 1, a controller 7 for adjusting the pulverization strength of the pulverizer 2, and multiple blending vessel lines A equipped with a particle size meter 3 for measuring the particle size of the coal pulverized by the pulverizer 2. The facility also includes an arithmetic and control device 6 for controlling the pulverization strength of the coal in the pulverizer 2 via the controller 7 based on a predetermined relationship between the pulverization strength of the coal in the pulverizer 2 in each blending vessel line A and the particle size of the coal after pulverization, so that the particle size of the coal after pulverization measured by the particle size meter 3 matches a target particle size. The pulverization facility distributes coal according to hardness ranges among the multiple blending vessel lines A and performs pulverization processing.

[0036] When the product of the hardness of the coal to be pulverized in each blending vessel line A and the coal feed rate is defined as the processing rate p, the arithmetic and control device 6 regresses the relationship between the crushing strength of the coal by the pulverizer 2 in each blending vessel line A and the coal particle size after crushing onto a straight line, determines the slope of the regression line r, and determines the equation of an approximation curve a drawn using the relationship between the slope of the regression line r and the processing rate p as coordinates. m When the processing amount p is changed due to a change in the coal blending plan, the amount of change Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated using the following (i) to (iii), and thereafter the crushing strength of the crusher 2 is controlled via the controller 7 so that the coal is crushed at the crushing strength (f + Δf). The details of the configuration, function and usage of such crushing equipment are as described above. (i) Processing volume p after change due to change in coal blending plan m Applying this to the equation for the fitted curve a, the modified processing volume p m The slope of the regression line e m " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder 2 is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, the particle size of the coal after grinding is measured by the particle size meter 3, and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The slope of the regression line e obtained in (i) above m " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the processing amount p after the change. m The amount of change in crushing strength Δf relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e m …(1)

[0037] A method for measuring the coal particle size (coarse particle ratio) using the particle size meter 3 will be described below. 9 is a schematic diagram showing one embodiment of a particle size meter 3 used in the present invention and its usage. This particle size meter 3 is composed of a CCD camera 30 that captures images of coal, and a particle size calculation device 31 (a device that processes images and calculates particle sizes based on the image processing) that processes the images captured by the CCD camera 30 and calculates the coal particle size (coarse particle ratio). The CCD camera 30 is installed above the coal bed being transported by the transport conveyor 5 (at a position close to the coal bed surface) and captures an image of the coal bed surface during transport. There are no particular restrictions on the installation height of the CCD camera 30, and it may be installed at a position where coal particles on the coal bed surface can be sufficiently observed (for example, at a height of about 500 mm from the coal bed surface) depending on the performance of the camera and lens. The shutter speed of the camera may be selected appropriately depending on the speed of the belt conveyor, the brightness of the captured image, etc.

[0038] The surface of the coal bed transported by the transport conveyor 5 is not flat but uneven, and the height is not constant. However, by using a camera lens with a wide range of focal depth for the CCD camera 30 (i.e., by performing an optical design that corresponds to the height variation due to unevenness), shortening the exposure time, and providing a light amount using a strobe light source (not shown) that can emit light instantaneously, a clear image without blurring can be obtained, and the coarse particle ratio can be accurately measured by image processing described below and calculation of the particle size based on that.

[0039] It is known that when vibration is applied to a layer of powder and granular material, coarse particles tend to gather at the surface due to the Brazilian nut effect. After crushing, the coal is loaded onto the conveyor 5 and transported. Initially, the coarse particles are buried in the layer. However, as the coal layer is transported by the conveyor 5, vibrations are applied, causing the coarse particles to move to the surface and become exposed due to the Brazilian nut effect. This coal layer surface is then imaged. There is thought to be a correlation between the particle size distribution of the imaged coal layer surface and the particle size distribution throughout the coal layer, making it possible to estimate the overall particle size distribution from the coal layer surface. To measure particle size after the coarse particles have been moved to the surface due to the Brazilian nut effect, it is preferable to place the particle size meter 3 at a certain distance from the crusher 2 (e.g., approximately 1–2 m away). The image of the coal bed surface obtained by the CCD camera 30 is sent to a particle size calculation device 31. This particle size calculation device 31 has an image processing unit 310 and a calculation unit 311. The image sent from the CCD camera 30 is processed by the image processing unit 310 to extract coarse particles, and the calculation unit 311 calculates the coarse particle ratio based on the extracted coarse particles. This coarse particle ratio is sent to the calculation control device 6 as a measurement value of the coal particle size, and is used to control the pulverizer 2 and to determine whether the pulverized particle size is appropriate.

[0040] FIG. 10 shows an outline of a processing flow for calculating the coarse particle ratio from an image captured by the CCD camera 30 in the particle size calculation device 31. When the image captured by the CCD camera 30 is input into the particle size calculation device 31, it is first subjected to a process to remove brightness variations (brightness correction). This brightness removal process removes brightness variations across the entire image caused by lighting conditions and the imaging angle. A commonly used image processing technique, known as shading correction, can be used. Next, the image is binarized, and then the watershed method is used to emphasize grain boundaries and identify particles from the image (particle separation). Specifically, to identify adjacent particles in the binarized image, watershed processing is performed, focusing on minute brightness differences, to separate adjacent particles. The areas of the particle images obtained through this process are individually calculated, and the particle diameters of the major and minor axes of these areas are calculated when these areas are approximated as ellipses. Next, only particles with a minor axis equal to or greater than a threshold are identified, thereby extracting only large, coarse particles from the coal particles. The weight of each extracted (identified) coarse particle is calculated from its particle size, and the sum of these weights is used to calculate the mass of the coarse particles in the coal. From this result, the coarse particle ratio (coal particle size) is calculated. The coarse particle ratio (coal particle size) calculated as described above is sent to the arithmetic and control device 6 in real time.

[0041] Although the above description has been made on the case where the coarse grain ratio is calculated by processing the image captured by the CCD camera 30, the coarse grain ratio may also be calculated using an optical device such as a 3D camera. The present invention is suitable as a method for crushing coal to produce coke, but is not limited to this. For example, the present invention can also be applied to coal crushing to obtain pulverized coal to be injected through tuyere in blast furnace operation. [Example]

[0042] When the present invention is implemented in a coal pulverization facility equipped with three blending vessel lines A1 to A3 as shown in FIG. 1, the processing amount p m1 ~p m3 The slope of the regression line (absolute value of the slope) e m1 ~e m3The crusher 2 provided in each blending tank A was a hammer crusher, and the particle size meter 3 used was the device for measuring the coarse particle ratio described above. Coal with an HGI of 80 or more and less than 100 was allocated to blending tank line A1, coal with an HGI of 60 or more and less than 80 to blending tank line A2, and coal with an HGI of 40 or more and less than 60 to blending tank line A3, and the coal was crushed on each line.

[0043] In carrying out the present invention, the "relationship between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization" was determined in advance for each blending vessel line A1 to A3. A target particle size after pulverization was determined for each blending vessel line A1 to A3, and the hammer rotation speed corresponding to the target particle size was determined based on the previously determined "correlation between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization." The coal was pulverized at this hammer rotation speed. The particle size of the coal after pulverization was measured using a particle size meter 3, and the coal was pulverized while adjusting the hammer rotation speed so that the particle size of the coal after pulverization would be the target particle size. The previously determined "relationship between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization" was regressed onto a straight line, and the absolute value of the slope of the regression line was determined. Figure 11 shows the "relationship between the hammer rotation speed of the pulverizer 2 and the particle size of the coal after pulverization" that was determined in advance for each blending tank line A1 to A3, and the regression lines r1 to r3 obtained by regressing this relationship onto a straight line, with absolute values ​​of slope e1 = 0.007, e2 = 0.0135, and e3 = 0.0198. In this embodiment, the particle size of the coal after pulverization (proportion of coarse coal particles) in FIG. 11 is the proportion of coarse particles with particle diameters of 6 mm or more.

[0044] The throughput p of each blending tank line A1 to A3 is p1=4.1, p2=3.5, and p3=2.4. As shown in FIG. 12, the absolute values ​​of the slopes e1 to e3 and the throughput p1 to p n The equation for the approximate curve a, which is drawn using the relationship between During operation, the coal blending plan was changed, and the processing volume p of blending tank lines A1 to A3 became p m1 =4, p m2 =3, p m3 = 2. Therefore, as shown in FIG. 13, the processing amount p m1 ~p m3Applying this to the equation for the approximate curve a in Figure 12, the processing volume p m1 ~p m3 The "slope of the regression line (absolute value of the slope)" corresponding to m1 :0.0086, e m2 :0.0159, e m3 :0.0232 was obtained. The throughput p of each blending tank line A1 to A3 may be defined as, for example, "coal hardness (HGI) x coal feed rate (coal cut rate)" as described above. However, other factors (for example, coal properties such as particle size and moisture) also affect the actual throughput. Therefore, the throughput p and p in Figs. 12 and 13 may be calculated by multiplying the actual throughput p by the amount of coal feed rate (HGI) x coal cut rate (coal cut rate). m is expressed as an index (dimensionless quantity) that takes into account these factors (i.e., factors that affect the ease of crushing) into account when calculating "coal hardness (HGI) x coal feed rate (coal cut rate)".

[0045] As explained above, in the present invention, even after the coal blending plan is changed, the coal is continued to be crushed for a certain period of time with the hammer rotation speed N remaining the same as before the change in the coal blending plan, the particle size of the crushed coal is measured, and the difference Δd between this measured particle size and the target particle size is calculated. m " and "the difference Δd between the measured particle size and the target particle size," a change ΔN in the hammer rotation speed relative to the hammer rotation speed N before the change in the coal blending plan is calculated. Thereafter, the coal is pulverized at that hammer rotation speed (N + ΔN). According to the present invention, it is possible to quickly and accurately change the coal pulverization conditions in response to changes in the coal blending plan, appropriately adjust and manage the pulverized coal particle size, and reduce variations in coal particle size and coke quality. [Explanation of symbols]

[0046] 1 Blending tank 2, 2a, 2b, 2c Crusher 3,3a,3b,3c Particle size meter 4,5 Transport conveyor 6. Arithmetic and control unit 7 Controller 8 monitors 30 CCD cameras 31 Particle size calculation device 310 Image Processing Unit 311 Arithmetic unit A, A1, A2, A3 blending tank line

Claims

1. The method for coal pulverization includes a plurality of blending vessel lines (A) including a plurality of blending vessels (1) for storing coal, a pulverizer (2) for pulverizing the coal discharged from the plurality of blending vessels (1), and a particle size meter (3) for measuring the particle size of the coal pulverized by the pulverizer (2), in which coal is sorted into the plurality of blending vessel lines (A) according to hardness range and pulverized, and in each blending vessel line (A), a relationship between the pulverization strength of the coal by the pulverizer (2) and the particle size of the coal after pulverization is determined in advance, and based on this relationship, the method for pulverizing coal is performed while adjusting the pulverization strength of the coal by the pulverizer (2) so that the particle size of the coal after pulverization measured by the particle size meter (3) is a target particle size, In each blending tank line (A), coals having different HGIs (Hardgrove Grindability Index) are stored in a plurality of blending tanks (1), and the coals discharged from these plurality of blending tanks (1) are subjected to a pulverization process. When the total value of the product of the coal cut amount from each blending tank (1) and the HGI of the coal in each blending tank line (A) (here, the total value is the sum of the values ​​calculated for each blending tank (1) (= coal cut amount × coal HGI)) is defined as the processing amount p, The relationship between the crushing strength of the coal by the crusher (2) in each blending vessel line (A) and the particle size of the coal after crushing is linearly regressed in advance to determine the slope of the regression line r, and an equation for an approximation curve a drawn using the relationship between the slope of the regression line r and the throughput p as a coordinate is determined; Any one or more blending tank lines (A ｍ a crushing strength change amount Δf relative to the crushing strength f before the change in the coal blending plan is calculated by the following steps (i) to (iii), and thereafter, the coal is crushed at the crushing strength (f + Δf). (i) Processing volume p after change due to change in coal blending plan ｍ is applied to the equation of the approximation curve a to obtain the changed processing amount p ｍ The slope of the regression line e ｍ " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder (2) is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, and the particle size of the coal after grinding is measured by the particle size meter (3), and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The "slope e of the regression line" obtained in (i) ｍ " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the changed processing amount p ｍ The amount of change Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e ｍ …(1)

2. 2. The method for crushing coal according to claim 1, wherein the crusher (2) is a hammer crusher, and the crushing strength of the coal by the crusher (2) is the number of revolutions of the hammers of the crusher (2).

3. 2. The coal crushing method according to claim 1, wherein the particle size meter (3) captures an image of the surface of the coal bed that has been crushed by the crusher (2) and is being transported by the transport conveyor, and measures the proportion of coarse particles in the coal based on the image.

4. Processing volume after change p ｍ the coal particle size measured by the particle size meter (3) becomes larger than the target particle size over time when the coal is pulverized at a pulverization strength (f+Δf) set according to the above.

5. The method for crushing coal according to claim 4, characterized in that the crusher (2) is a hammer crusher, and the change in the crushing method in the crusher (2) is one or more of the following (i) and (ii): (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2).

6. 6. The coal pulverization method according to claim 5, wherein the change in the pulverization method in the pulverizer (2) is performed by giving priority to the following (i), and if the coal particle size after pulverization measured by the particle size meter (3) is still larger than the target particle size after the change in the pulverization method, the following (ii) is performed. (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2).

7. The coal crushing equipment includes a plurality of blending tank lines (A) including a plurality of blending tanks (1) for storing coal, crushers (2) for crushing the coal discharged from the plurality of blending tanks (1), a controller (7) for adjusting the crushing strength of the crushers (2), and a particle size meter (3) for measuring the particle size of the coal crushed by the crushers (2), and an arithmetic and control device (6) for controlling the crushing strength of the coal in the crushers (2) via the controller (7) based on a predetermined relationship between the crushing strength of the coal by the crushers (2) in each blending tank line (A) and the particle size of the coal after crushing and the crushed coal, so that the particle size of the coal after crushing measured by the particle size meter (3) becomes a target particle size, the coal being sorted into the plurality of blending tank lines (A) according to hardness ranges and crushed, and in each blending tank line (A), coals of different HGIs (Hardgrove Grindability Index) are stored in the plurality of blending tanks (1), and the coal discharged from the plurality of blending tanks (1) is crushed; The arithmetic and control device (6) calculates a processing amount p by linearly regressing the relationship between the crushing strength of the coal by the crusher (2) in each blending tank line (A) and the particle size of the coal after crushing to obtain a slope of the regression line r, and then calculating an equation for an approximation curve a plotted as a coordinate of the relationship between the slope of the regression line r and the processing amount p. The arithmetic and control device (6) calculates a processing amount p by linearly regressing the relationship between the crushing strength of the coal by the crusher (2) in each blending tank line (A) and the particle size of the coal after crushing to obtain a slope of the regression line r, and then calculating an equation for an approximation curve a plotted as a coordinate of the relationship between the slope of the regression line r and the processing amount p. ｍ When a processing amount p is changed due to a change in the coal blending plan, a change amount Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated by the following (i) to (iii), and thereafter the crushing strength of the crusher (2) is controlled via a controller (7) so that the coal is crushed at the crushing strength (f+Δf). (i) Processing volume p after change due to change in coal blending plan ｍ is applied to the equation of the approximation curve a to obtain the changed processing amount p ｍ The slope of the regression line e ｍ " We demand. (ii) Even after the coal blending plan is changed, the grinding of the coal by the grinder (2) is continued for a certain period of time at the same grinding intensity as before the change in the coal blending plan, and the particle size of the coal after grinding is measured by the particle size meter (3), and the difference Δd between this measured particle size and the target particle size is calculated. (iii) The "slope e of the regression line" obtained in (i) ｍ " and the "difference Δd between the measured particle size and the target particle size" calculated in (ii) above, the following formula (1) is used to calculate the changed processing amount p ｍ The amount of change Δf in the crushing strength relative to the crushing strength f before the change in the coal blending plan is calculated. Δf=Δd / e ｍ …(1)

8. 8. The coal crushing facility according to claim 7, wherein the crusher (2) is a hammer crusher, and the crushing strength of the coal by the crusher (2) is the number of revolutions of the hammers of the crusher (2).

9. The coal crushing facility according to claim 7, wherein the particle size meter (3) takes an image of the surface of the coal bed that has been crushed by the crusher (2) and is being transported by the transport conveyor, and measures the proportion of coarse particles in the coal based on the image.

10. The arithmetic and control device (6) changes the processing amount p ｍ 8. The coal crushing equipment according to claim 7, wherein, when coal is crushed at a crushing strength (f+Δf) set according to the above, if the coal particle size after crushing measured by the particle size meter (3) becomes larger than the target particle size over time, the equipment determines that the crushed particle size is inappropriate due to a factor of the crusher (2) itself, and outputs the determination result or an instruction to change the crushing method of the crusher (2) based on the determination result.

11. The coal crushing equipment according to claim 10, characterized in that the crusher (2) is a hammer crusher, and the crushing method of the changeable crusher (2) is one or more of the following (i) and (ii): (i) Changing the rotation direction of the hammer of the crusher (2). (ii) Changing the gap between the hammer and the repulsion plate of the crusher (2).

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