Raw material crushing method , coke manufacturing method, and raw material crushing device

Abstract

This raw material crushing method is carried out by a raw material crushing device (14) in a crushing facility having a crusher (2) for crushing a raw material, a conveying line for conveying the crushed raw material, and a measuring device for measuring the particle size of the conveyed raw material. The raw material crushing method includes acquiring the measured particle size from the measurement device, predicting a time at which the crushing strength of the crusher will be changed on the basis of the measured particle size and a predetermined target particle size range, and outputting a signal for changing the crushing strength of the crusher at the predicted time.

Description

Method for crushing raw materials, method for producing coke, and raw material crushing device

[0001] The present disclosure relates to a raw material pulverization method, a coke manufacturing method, and a raw material pulverization device.

[0002] For example, in the ironmaking process, the coke in the blast furnace must be high-strength and have small particle size variations (uniformity) to ensure good gas permeability within the furnace. To produce uniform high-strength coke, the raw material coal must be heated and carbonized in the coke oven, and the bulk density of the coal charged into the coke oven must be increased. Therefore, it is important to optimize the particle size of the coal charged into the coke oven.

[0003] Coarse coal with large particle size undergoes cracking at the contact interface due to differences in contraction rates between adjacent coal particles during heating in a coke oven, reducing its strength. Furthermore, fine coal with small particle size floats in the air when charged into the coke oven, reducing the bulk density of the coal charged. Therefore, in order to produce uniform high-strength coke, it is necessary to select crushing conditions when crushing coal in a crusher to achieve the target particle size and reduce the variation in particle size of the coal after crushing.

[0004] For example, Patent Documents 1 and 2 disclose methods for measuring the particle size of coal after crushing or the particle size of coal before and after crushing, and changing the crushing intensity for each crusher based on the particle size change calculated from the measurement results, so that the particle size of the coal after crushing becomes a target particle size.

[0005] JP 2004-16983 A JP 2018-51425 A

[0006] However, in order to reduce variation in the particle size of the coal after crushing using the methods described in Patent Documents 1 and 2, an operator must constantly check the particle size of the coal after crushing or the particle size of the coal before and after crushing, which places an excessive workload on the operator. Furthermore, frequently changing the crushing strength during operation places a heavy load on the crushing equipment. Furthermore, changing the crushing strength of a crusher requires a certain time (e.g., about 10 minutes) from the time the changed crushing strength is instructed to the crusher until it is reflected. During this certain time, there is a problem of variation in the particle size of the coal after crushing.

[0007] The purpose of the present disclosure, made in consideration of the above circumstances, is to provide a raw material crushing method, a coke manufacturing method, and a raw material crushing device that can reduce variation in particle size of the raw material after crushing by setting the crushing intensity based on predictions.

[0008] (1) A method for crushing raw materials according to one embodiment of the present disclosure is a method for crushing raw materials performed by a raw material crushing device in crushing equipment having a crusher for crushing raw materials, a conveying line for conveying the crushed raw materials, and a measuring device for measuring the particle size of the conveyed raw materials, the method including: acquiring the particle size measured from the measuring device; predicting a time to change the crushing strength of the crusher based on the measured particle size and a predetermined target particle size range; and outputting a signal to change the crushing strength of the crusher at the predicted time.

[0009] (2) As one embodiment of the present disclosure, in (1), the measuring device continuously measures the particle size, and predicting the time is performed by calculating a transition of the measured particle size and calculating the time at which the transition will cause the particle size to fall outside the target particle size range.

[0010] (3) As one embodiment of the present disclosure, in (1) or (2), the predicted time is corrected based on the granularity measured after the time of prediction.

[0011] (4) As an embodiment of the present disclosure, in any one of (1) to (3), the change in the crushing strength of the crusher includes a change in the amount of coal fed into the crusher and a change in the rotation speed of a hammer of the crusher.

[0012] (5) A method for producing coke according to one embodiment of the present disclosure includes changing the crushing strength of the crusher by any one of the raw material crushing methods (1) to (4), wherein the raw material is coal, and producing coke by heating the coal crushed by the crusher in a coke oven.

[0013] (6) A raw material crushing device according to one embodiment of the present disclosure is a raw material crushing device used in a crushing facility having a crusher for crushing raw materials, a conveying line for conveying the crushed raw materials, and a measuring device for measuring the particle size of the conveyed raw materials, and includes: an acquisition unit that acquires the particle size measured from the measuring device; a prediction unit that predicts the time to change the crushing strength of the crusher based on the measured particle size and a predetermined target particle size range; and an output unit that outputs a signal to change the crushing strength of the crusher at the predicted time.

[0014] According to the present disclosure, it is possible to provide a raw material crushing method, a coke manufacturing method, and a raw material crushing device that can reduce variation in particle size of the raw material after crushing by setting the crushing intensity based on prediction.

[0015] FIG. 1 is a diagram showing the overall configuration of a raw material pulverization facility. FIG. 2 is a detailed diagram of a portion of the pulverization facility of FIG. 1. FIG. 3 is a diagram showing an example configuration of a raw material pulverization device according to an embodiment of the present disclosure. FIG. 4 is a flowchart illustrating processing of a raw material pulverization method according to an embodiment of the present disclosure. FIG. 5 is a diagram showing an example of time series data of the proportion of coarse coal particles of 6 mm or more when particle size is continuously measured. FIG. 6 is a diagram showing an example of calculation of particle size transitions using the time series data of FIG. 5.

[0016] Hereinafter, a raw material pulverization method, a coke manufacturing method, and a raw material pulverization device 14 according to an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 shows the overall configuration of the raw material pulverization equipment. FIG. 2 is a detailed view of a portion 10 of the pulverization equipment of FIG. 1, including a measuring device 13 and the raw material pulverization device 14. FIG. 3 is a block diagram showing an example configuration of the raw material pulverization device 14. The raw material pulverization device 14 is used in a pulverization equipment having a pulverizer 2 that pulverizes the raw material, a conveying line that conveys the pulverized raw material, and a measuring device 13 that measures the particle size of the conveyed raw material, and sets the pulverization intensity based on prediction, as described below.

[0017] The raw material crushing equipment shown in FIG. 1 represents a coal crushing line for coke ovens. In this embodiment, the raw material is coal. The raw material is not limited to coal, as long as it can be crushed to minimize particle size variation. Coal stored in a yard 1 by brand is transported to a crusher 2 by brand, crushed to a target particle size range 101 (see FIG. 5), and stored in a blending tank 4. Here, the particle size refers to the ratio of particle sizes within a predetermined range (e.g., 6 mm or more) (see FIG. 5). The target particle size range 101 is the range that the crushed coal 12 must satisfy in order to produce uniformly high-strength coke, and is determined based on the quality required for the coke to be produced. While three crushers 2 are shown in the example of FIG. 1 , the number of crushers 2 is not limited to a specific number; any number greater than one may be used. Coal is transported to each crusher 2, and the crusher 2 crushes the coal in accordance with a signal (control signal) from a raw material crushing device 14. The control signal includes an instruction to change the crushing strength of the pulverizer 2. Changing the crushing strength of the pulverizer 2 includes changing the amount of coal fed into the pulverizer 2 and changing the rotation speed of the hammers of the pulverizer 2. In addition, a measuring device 13 that measures the particle size of the pulverized coal 12 is provided, for example, above the belt conveyor 11 (part of the conveying line) on the outlet side of the pulverizer 2. The measuring device 13 may continuously measure the particle size at a specific position 3 set on the belt conveyor 11 on the outlet side of the pulverizer 2. The coal stored in the blending tank 4 is transported to the coke oven 5, where it is heated and carbonized to produce coke.

[0018] As shown in FIG. 2 , the pulverized coal 12 is transported in the transport direction to the blending tank 4 by the belt conveyor 11. The measuring device 13 measures the pulverized coal 12. The measuring device 13 outputs the measurement results to the raw material pulverizer 14. The measurement results are particle sizes measured by the measuring device 13. In this embodiment, the measuring device 13 includes a camera and captures two-dimensional images of the pulverized coal 12 stacked on the belt conveyor 11. The measuring device 13 identifies the two-dimensional shape of the pulverized coal 12 from the captured two-dimensional image and calculates and obtains the particle size using a known method (image processing). The image processing may include, for example, binarization, contour extraction, etc.

[0019] As shown in FIG. 3 , the raw material crushing device 14 includes an acquisition unit 15, a prediction unit 16, and an output unit 17. The acquisition unit 15 acquires the particle size measured by the measuring device 13. The prediction unit 16 predicts the time to change the crushing strength of the crusher 2 based on the measured particle size and a predetermined target particle size range 101. Details of the time prediction will be described later. The output unit 17 outputs a signal to change the crushing strength of the crusher 2 at the time predicted by the prediction unit 16. Here, the raw material crushing device 14 may be configured as hardware, for example, a computer. The computer may be a server computer or a portable computer such as a laptop or tablet. In this embodiment, the raw material crushing device 14 is a computer used in the raw material crushing equipment. In addition, in this embodiment, the target particle size range 101 is stored in the computer's storage device.

[0020] FIG. 4 is a flowchart illustrating the processing of a raw material grinding method performed by a raw material grinding device 14 in a grinding facility having a grinder 2 that grinds raw materials, a conveying line that conveys the ground raw materials, and a measuring device 13 that measures the particle size of the conveyed raw materials.

[0021] The acquiring unit 15 acquires a predetermined target granularity range 101 from, for example, a storage device (step S1).

[0022] The acquisition unit 15 also acquires the particle size of the raw material measured by the measuring device 13 (step S2).

[0023] The prediction unit 16 predicts the time to change the crushing intensity of the crusher 2 based on the measured particle size and the target particle size range 101 acquired by the acquisition unit 15 (step S3). Here, in this embodiment, the time prediction is performed by calculating the transition of the measured particle size (see FIG. 5) and calculating (predicting) the time when the transition will deviate from the target particle size range 101.

[0024] If there is sufficient time until the predicted time (Yes in step S4), the prediction unit 16 returns to the processing of step S2. For example, "there is sufficient time until the predicted time" may mean that the time from the current time to the predicted time is equal to or greater than a predetermined time (e.g., one hour). The acquisition unit 15 acquires a newly measured particle size of the raw material from the measuring device 13 (step S2). The prediction unit 16 then predicts the time to change the grinding strength of the grinder 2 using the newly measured particle size (step S3). Step S3 from the second time onward corresponds to a process of correcting the predicted time. In other words, the predicted time is corrected based on particle sizes measured after the prediction. This time correction can improve the accuracy of the prediction.

[0025] If there is not enough time until the predicted time (No in step S4), the prediction unit 16 proceeds to the process of step S5. Then, the output unit 17 outputs a signal to change the crushing strength of the crusher 2 when the time predicted by the prediction unit 16 arrives (step S5). The output signal is, for example, a control signal for the crusher 2.

[0026] The effects of the present disclosure will be specifically described below based on examples, but the present disclosure is not limited to these examples.

[0027] FIG. 5 shows time-series data of the proportion of coarse coal particles 6 mm or larger when particle size is continuously measured. Here, coarse coal refers to coal with large particle sizes, as described above. From FIG. 5, it can be seen that the particle size of the coal after pulverization changes from moment to moment. This change is thought to be caused by, for example, changes in the moisture content and other properties of the coal before pulverization, or by some of the coal with high moisture content adhering to the pulverization equipment due to pulverization.

[0028] FIG. 6 shows an example of particle size transition calculation using the time-series data of FIG. 5 and explains the method for calculating the time when the particle size falls outside the target range. Specifically, FIG. 6 shows the measurement results from "3:00" to "3:30" in FIG. 5. The particle size was measured every minute by the measuring device 13, and the average particle size was calculated by averaging 10 consecutive points. A regression equation was calculated from the average particle size value. The resulting regression equation was y = 0.0766x + 5.9808, indicating that the particle size transitions at a rate of 0.0766% per minute. Here, y is the percentage [%] of coarse coal particles 6 mm or larger. Furthermore, x is the time [minutes] elapsed since "3:00." According to the regression equation, the time when the target particle size upper limit 102, which is the upper limit of the target particle size range 101, will be exceeded is predicted 79 minutes later, i.e., at "4:19." In this example, the target particle size upper limit 102 is 12%. For example, in FIG. 5, data exceeding the target granularity upper limit 102 is shown shortly before "5:00."

[0029] Then, at the predicted time (4:19 in this example), taking into account operational conditions such as yield, the amount of coal fed into the pulverizer 2 or the rotation speed of the hammers of the pulverizer 2 is changed. This type of control prevents the particle size from deviating from the target particle size range 101, thereby reducing variation in the particle size of the coal after pulverization. Furthermore, the raw material pulverizer 14 may calculate an improved particle size value for the amount of change in the crushing strength, and further adjust the crushing strength of the pulverizer 2 so that the particle size approaches the center of the target particle size range 101 (8% in the example of FIG. 5 ).

[0030] 5 shows a case where particle size measurement was continued without changing the crushing strength of the crusher 2. If the above-described raw material crushing method is carried out and the crushing strength of the crusher 2 is changed at the predicted time of "4:19", it is considered that the particle size will change within the target particle size range 101 without reaching the target particle size upper limit 102.

[0031] As described above, the raw material pulverization method, coke manufacturing method, and raw material pulverization device 14 according to the present embodiment are configured as described above to reduce variation in the particle size of the pulverized raw material by setting the pulverization intensity based on prediction. That is, the raw material pulverization method, coke manufacturing method, and raw material pulverization device 14 according to the present embodiment determine a target particle size range 101 in advance, predict the time when the particle size of the pulverized raw material will fall outside the target particle size range 101, and change the pulverization intensity at the predicted time. This control reduces variation in the particle size of the raw material. Furthermore, because the time for changing the pulverization intensity is determined in advance, the operator's workload is not excessive. Furthermore, because the pulverization intensity needs to be changed only when the particle size of the pulverized raw material is predicted to fall outside the particle size range, a heavy load is not placed on the pulverization equipment.

[0032] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. For example, functions included in each component or step can be rearranged so as not to cause logical inconsistencies, and multiple components or steps can be combined or divided into one. The embodiments of the present disclosure can also be realized as a program executed by a processor included in an apparatus or a storage medium on which a program is recorded. It should be understood that these are also included within the scope of the present disclosure.

[0033] For example, coal does not have to be crushed by brand. For example, coals may be blended before crushing, and the particle size of the blended coals after crushing may be continuously measured. Then, using the same method as in the above embodiment, the time to change the crushing strength may be predicted, and the crushing strength may be changed at the predicted time.

[0034] In the above embodiment, the pulverized coal 12 is identified from a two-dimensional image captured by a camera. As another example, the measurement device 13 may be a laser rangefinder or the like, which performs three-dimensional measurement, and the obtained three-dimensional data may be used to identify the pulverized coal 12 and calculate the particle size of the pulverized coal 12.

[0035] Furthermore, the raw material crushing device 14 may not be a single device, but may be composed of multiple devices located in multiple locations and capable of transmitting and receiving data to and from each other via a network. In other words, multiple devices connected via a network may function as the raw material crushing device 14 as a whole. Therefore, for example, the raw material crushing device 14 may be composed of a single computer as a hardware configuration, or multiple computers connected via a network. When composed of multiple computers, a shared memory accessible by each computer may be used to share data or programs. For example, the output unit 17 of the raw material crushing device 14 may be a single device (crushing strength instruction device) that outputs an instruction signal (control signal) regarding the crushing strength to the crusher 2. In this case, the parts of the raw material crushing device 14 excluding the output unit 17 may be separate devices (crushing control devices).

[0036] Furthermore, when the raw material crushing device 14 is configured by a computer, one or more programs used to control the operation of the raw material crushing device 14 may be stored in a storage device (e.g., memory) of the computer. When the program stored in the storage device is read by a processor included in the computer, the processor may function as the acquisition unit 15, the prediction unit 16, and the output unit 17. Then, the processing of the raw material crushing method may be executed by the computer.

[0037] DESCRIPTION OF SYMBOLS 1 Yard 2 Crusher 3 Specific position 4 Blending tank 5 Coke oven 10 Part of crushing equipment 11 Belt conveyor 12 Crushed coal 13 Measuring device 14 Raw material crushing device 15 Acquisition unit 16 Prediction unit 17 Output unit 101 Target particle size range 102 Target particle size upper limit

Claims

1. A method for crushing raw materials in crushing equipment having a crusher for crushing raw materials, a conveying line for conveying the crushed raw materials, and a measuring device for measuring the particle size of the conveyed raw materials, the method comprising: acquiring the particle size measured from the measuring device; predicting a time to change the crushing strength of the crusher based on the measured particle size and a predetermined target particle size range; and outputting a signal to change the crushing strength of the crusher at the predicted time.

2. A method for grinding raw materials as described in claim 1, wherein the measuring device continuously measures the particle size, and the time prediction is performed by calculating the trend of the measured particle size and calculating the time at which the particle size will fall outside the target particle size range from the trend.

3. A method for grinding raw materials according to claim 1 or 2, wherein the predicted time is corrected based on the particle size measured after the predicted time.

4. A method for crushing raw materials according to any one of claims 1 to 3, wherein changing the crushing strength of the crusher includes changing the amount of coal being fed into the crusher and changing the rotation speed of the hammers of the crusher.

5. A method for producing coke, in which the crushing strength of the crusher is changed by the method for crushing raw materials described in any one of claims 1 to 3, the raw material is coal, and the coal crushed by the crusher is heated in a coke oven to produce coke.

6. A raw material crushing device used in a crushing facility having a crusher for crushing raw materials, a conveying line for conveying the crushed raw materials, and a measuring device for measuring the particle size of the conveyed raw materials, comprising: an acquisition unit that acquires the particle size measured by the measuring device; a prediction unit that predicts the time to change the crushing strength of the crusher based on the measured particle size and a predetermined target particle size range; and an output unit that outputs a signal to change the crushing strength of the crusher at the predicted time.

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