Particle size estimation method and particle size estimation device

Abstract

A particle size estimation device 10 includes a sound sensor 14 and an information processing unit 15. The sound sensor 14 is positioned near a prescribed piece of equipment 11. The prescribed piece of equipment 11 handles particles to be measured. The sound sensor 14 collects collision sounds when particles containing a plurality of particles are caused to collide with the prescribed piece of equipment 11. The information processing unit 15 executes estimation related to the size of the particles, on the basis of the sound collected by the sound sensor 14.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Patent Application No. 2022-007397, filed in Japan on January 10, 2022, the entire disclosure of which is incorporated herein by reference. [Technical field]

[0002] The present invention relates to a particle size estimation method and a particle size estimation device. [Background technology]

[0003] In the steelmaking process, the coke in the blast furnace is required to be high strength and uniform to ensure gas permeability in the furnace. To produce uniform high strength coke, the coal particle size is adjusted to an ideal particle size ratio so that the particles will come into strong contact when the coal is heated and carbonized in the coke oven and the bulk density of the coal charged into the coke oven is increased.

[0004] Larger particles are more likely to crack at the contact interface due to the difference in shrinkage rate between adjacent coal particles during heat treatment, resulting in a decrease in coke strength. On the other hand, smaller fine particles are more likely to fly into the air when charged into a coke oven, lowering the bulk density. Therefore, in order to produce high-strength, uniform coke, it is necessary to adjust the grinding conditions so that the particle size of the crushed coal for coke production falls within the target particle size range. Furthermore, although the grinding conditions can be changed based on the coal properties, such as the particle size before and after grinding, it is important to measure the particle size of the coal before and after grinding.

[0005] Conventionally, in measuring the particle size of coal, it has been proposed to identify images of coal in a two-dimensional image taken of the coal using a camera, and calculate the particle size distribution by calculating the particle size of each identified coal (see Patent Document 1).Also, a particle size measurement method has been proposed in which a laser is irradiated onto coal, and the particle size is calculated from the angle of the scattered laser light (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-016983 A [Patent Document 2] JP 2012-173241 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the particle size distribution calculation method proposed in Patent Document 1 does not include information on the depth direction of the image, in other words, the height direction, so when two or more particles are stacked, the particle in the lower layer cannot be identified. This makes it difficult to measure the particle size accurately. In addition, in the particle size measurement method proposed in Patent Document 2, the particle size is calculated from the diffraction angle of the laser irradiated onto the coal, so the diffraction angle increases as the particle size increases. This makes it difficult to measure particles with a large particle size, such as coal before crushing.

[0008] Therefore, an object of the present disclosure, made in consideration of the above-mentioned problems in the conventional technology, is to provide a particle-size estimation method and a particle-size estimation device that can accurately estimate particle sizes. [Means for solving the problem]

[0009] In order to solve the above problems, a particle size estimation method according to a first aspect includes the steps of: Multiple particles are collided with a specified facility, A sound of the particles colliding with the predetermined equipment is collected by an acoustic sensor; An estimation is made regarding the particle size of the particles based on the sound collected by the acoustic sensor.

[0010] A particle size estimation device according to a second aspect comprises: an acoustic sensor that is located near a predetermined facility that handles the particles to be measured and collects collision sounds generated when particles including a plurality of the particles collide with the predetermined facility; and an information processing unit that performs an estimation regarding the particle size of the particles based on the sound collected by the acoustic sensor. Effect of the Invention

[0011] According to the particle size estimation method and particle size estimation device according to the present disclosure configured as described above, accurate estimation of particle sizes can be performed. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a layout diagram of a particle size estimation device according to the present embodiment with respect to a specific facility. [Diagram 2] 2 is a functional block diagram showing a schematic configuration of an information processing unit in FIG. 1. [Diagram 3] 3 is a flowchart for explaining a pre-sampling process executed by a control unit in FIG. 2. [Figure 4] 3 is a flowchart for explaining a particle size estimation process executed by a control unit in FIG. 2. [Diagram 5] 11A to 11C are first, second and third graphs showing the change over time in sound pressure in the 0.5 kHz band when coal with particle sizes of 31.5 to 45 mm, coal with particle sizes of 16 to 31.5 mm, and coal with particle sizes of 16 to 45 mm are collided against a hopper. [Figure 6] 4A and 4B are fourth and fifth graphs showing time changes in sound pressure in the 0.5 kHz and 14 kHz bands, respectively, when coal having a particle size of 9 to 16 mm is collided against a hopper. [Figure 7] 6A and 6B are sixth and seventh graphs showing the time change in sound pressure in the 14 kHz band when coal having particle sizes of 31.5 to 45 mm and coal having particle sizes of 16 to 31.5 mm are collided against a hopper. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] FIG. 1 is a schematic diagram of a particle size estimation device 10 according to an embodiment of the present disclosure. The particle size estimation device 10 is provided in a predetermined facility 11 that handles an aggregate of a plurality of particles 13 to be measured. The plurality of particles includes, for example, coal of 5 mm or more. The predetermined facility 11 is a facility that causes collisions with the particles 13. The predetermined facility 11 is, for example, a storage hopper. A plurality of particles 13 conveyed by a conveyor 12 are fed into the predetermined facility 11 from above vertically, and collide with the side of the predetermined facility 11. The particle size estimation device 10 estimates the particle size of the plurality of particles 13 based on the collision sound between the predetermined facility 11 and the plurality of particles 13.

[0015] The particle size estimation device 10 includes an acoustic sensor 14 and an information processing unit 15.

[0016] The acoustic sensor 14 is located near a predetermined facility. The acoustic sensor 14 is, for example, a microphone. The acoustic sensor 14 collects collision sounds generated when a plurality of particles 13 collide with the predetermined facility 11. More specifically, the acoustic sensor 14 collects sounds including the collision sounds. The acoustic sensor 14 is expected to collect sounds in an audible range of 20 kHz or less, and a sensor capable of detecting the sounds may be selected.

[0017] The information processing unit 15 may be a server device or a personal computer. The information processing unit 15 estimates the particle size of the particles based on the sound collected by the acoustic sensor 14. As shown in Fig. 2, the information processing unit 15 includes, for example, an interface 16, an input unit 17, an output unit 18, a storage unit 19, and a control unit 20.

[0018] The interface 16 communicates information with external devices. For example, the interface 16 acquires, as a signal, sound collected by the acoustic sensor 14. The interface 16 may transmit and receive information to and from external devices other than the acoustic sensor 14.

[0019] The input unit 17 includes one or more interfaces for detecting user input. For example, the input unit 17 may be, but is not limited to, a physical key, a capacitive key, a touch screen integrated with the display of the output unit 18, a microphone for receiving voice input, or a camera for capturing an image of a subject.

[0020] The output unit 18 includes one or more interfaces that output information to notify the user. For example, the output unit 18 is a display that outputs information as a video, or a speaker that outputs information as a sound, but is not limited to these.

[0021] The storage unit 19 is, but is not limited to, a semiconductor memory, a magnetic memory, an optical memory, or the like. The storage unit 19 may function as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 19 stores any information used in the operation of the information processing unit 15. The storage unit 19 may store, for example, a system program, an application program, or the like. The storage unit 19 may store sound corresponding to the environmental sound of the specified facility 11, as described later. The environmental sound of the specified facility 11 is the surrounding sound generated when the multiple particles 13 are input into the specified facility 11, excluding the collision sound when the multiple particles 13 collide with the specified facility 11.

[0022] The control unit 20 includes one or more processors. The processor may be, but is not limited to, a general-purpose processor or a dedicated processor specialized for a specific process. The dedicated processor may include an application specific integrated circuit (ASIC). The control unit 20 may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The control unit 20 controls each part of the information processing unit 15.

[0023] The control unit 20 may have an advance sample mode and a particle size estimation mode as operation modes. In the advance sample mode, the control unit 20 may collect environmental sounds of a given facility 11. In the particle size estimation mode, the control unit 20 may perform estimation regarding particle size. Switching between the advance sample mode and the particle size estimation mode may be based on an operation input to the input unit 17.

[0024] In the pre-sample mode, the user of the particle size estimation device 10 is instructed to collect environmental sounds of a given facility 11 before estimating particle size without causing collision of particles 13. For example, the user is instructed to input an operation input to the input unit 17 to cause the acoustic sensor 14 to collect sound while the conveyor 12 is operating with nothing placed on it.

[0025] In the pre-sample mode, the control unit 20 may recognize the sound collected by the acoustic sensor 14 as environmental sound and store it in the memory unit 19. Furthermore, the control unit 20 may separate the sound into multiple frequency bands by FFT analysis. The control unit 20 may store in the memory unit 19, in each of the separated frequency bands, a frequency band having a sound pressure equal to or higher than a threshold, as a frequency band of environmental sound.

[0026] In the particle size estimation mode, a user of the particle size estimation device 10 is instructed to cause the acoustic sensor 14 to collect sound while a particle 13 is colliding with a predetermined facility 11. In the particle size estimation mode, the control unit 20 performs an estimation regarding the particle size of the particle based on the sound collected by the acoustic sensor 14, as described below.

[0027] For the purpose of estimation, the control unit 20 may extract the particle collision sound from the sound collected by the acoustic sensor 14. The control unit 20 may extract the particle collision sound by canceling the sound corresponding to the environmental sound of the predetermined facility 11 stored in the storage unit 19 from the sound collected in the particle size estimation mode.

[0028] More specifically, in the particle size estimation mode, the control unit 20 may separate the collected sound into a plurality of frequency bands, for example, by FFT analysis. The control unit 20 may cancel and extract, for example, environmental sound collected in the pre-sampling mode from the separated plurality of frequency bands, or may extract frequency bands other than the sound frequency band as particle collision sound.

[0029] The control unit 20 may separate the collected sound into a plurality of frequency bands and estimate the particle size of the particles based on the collision sounds of the plurality of frequency bands. As described above, the control unit 20 may estimate the particle size of the particles based on the extracted collision sounds of the particles, in other words, on the collision sounds of the plurality of frequency bands excluding the environmental sounds.

[0030] For example, the control unit 20 may determine whether or not the sound pressure of a first band among the separated frequency bands exceeds a first threshold value. When the sound pressure of the first band exceeds the first threshold value, the control unit 20 may estimate that the particles 13 having a first particle size or larger corresponding to the first band are included in the plurality of particles.

[0031] The first particle size may be determined arbitrarily. The first particle size may be, for example, the upper limit of a desired particle size range in a given facility 11. The first particle size is, for example, 31.5 mm. The first band may be a frequency band in which a change in sound pressure becomes clear depending on whether the particle 13 to be measured exceeds the determined first particle size. In a configuration in which the first particle size is 31.5 mm, the first band is a 0.5 kHz band. Also, the first threshold value is 0.05 m / s 2 The 0.5 kHz band is, for example, a band of a predetermined width centered at 0.5 kHz. The predetermined width may be zero, in other words, 0.5 kHz itself, or may have a width.

[0032] Furthermore, the control unit 20 may, for example, calculate a ratio of the maximum sound pressure of the impact sound in a third band to the maximum sound pressure of the impact sound in a second band among the multiple separated frequency bands. The third band is a frequency range larger than the second band. The control unit 20 may determine whether the ratio exceeds a second threshold value. If the ratio exceeds the second threshold value, the control unit 20 may estimate that the multiple particles include only particles 13 having a particle size equal to or smaller than the second particle size corresponding to the second band and the third band.

[0033] The second particle size may be arbitrarily determined. The second particle size may be, for example, the lower limit of a desired particle size range in a given facility 11. The second particle size is, for example, 16 mm. The second and third frequency bands may be determined as frequency bands in which the change in the ratio of sound pressures becomes clear depending on whether the particles 13 to be measured exceed the determined second particle size. The second band may be the same as the first band, or may be different. In a configuration in which the second particle size is 16 mm, the second and third bands are 0.5 kHz and 14 kHz, respectively. The second threshold value is 3. The 14 kHz band is, for example, a band of a given width centered on 14 kHz. The given width may be zero, in other words, 0.5 kHz itself, or may have a width.

[0034] After estimating the particle size of the particle, the control unit 20 may cause the output unit 18 to output the estimation result. Alternatively, the control unit 20 may provide the estimation result to an external device that performs a predetermined process on the particle 13 based on the estimated particle size.

[0035] Next, the pre-sampling process executed by the control unit 20 in this embodiment will be described with reference to the flowchart of Fig. 3. The pre-sampling process starts when the operation mode of the control unit 20 is switched to the pre-sampling mode.

[0036] In step S100, the control unit 20 determines whether or not the input unit 17 detects an operation input that starts sound collection by the acoustic sensor 14. If not, the process returns to step S100. If detected, the process proceeds to step S101.

[0037] In step S101, the control unit 20 starts acquiring sound. The control unit 20 starts storing the acquired sound, for example, in the storage unit 19. After the start of acquisition, the process proceeds to step S102.

[0038] In step S102, the control unit 20 determines whether or not the input unit 17 detects an operation input for terminating sound collection by the acoustic sensor 14. If not, the process repeats step S102. If detected, the process proceeds to step S103.

[0039] In step S103, the control unit 20 stops acquiring the sound. After stopping, the process proceeds to step S104.

[0040] In step S104, the control unit 20 separates the sound acquired from step S101 to step S103 into a plurality of frequency bands by FFT analysis. After the separation, the process proceeds to step S105.

[0041] In step S105, the control unit 20 recognizes, from among the multiple frequency bands separated in step S104, a frequency band that includes a sound pressure equal to or greater than a threshold as an amplitude, as a frequency band of environmental sound. After the recognition, the process proceeds to step S106.

[0042] In step S106, the control unit 20 stores the frequency band determined in step S105 as the frequency band of the environmental sound in the storage unit 19. After storing, the pre-sampling process ends.

[0043] Next, the particle size estimation process executed by the control unit 20 in this embodiment will be described with reference to the flowchart of Fig. 4. The particle size estimation process starts when the operation mode of the control unit 20 is switched to the particle size estimation mode.

[0044] In step S200, the control unit 20 determines whether or not the input unit 17 detects an operation input that starts sound collection by the acoustic sensor 14. If not, the process returns to step S200. If detected, the process proceeds to step S201.

[0045] In step S201, the control unit 20 starts acquiring sound. The control unit 20 starts storing the acquired sound, for example, in the storage unit 19. After starting acquisition, the process proceeds to step S202.

[0046] In step S202, the control unit 20 separates the sound that has started to be acquired in step S201 into a plurality of frequency bands by FFT analysis. After the separation, the process proceeds to step S203.

[0047] In step S203, the control unit 20 cancels, from among the frequency bands separated in step S202, the frequency band of the environmental sound stored in the storage unit 19. After the cancellation, the process proceeds to step S204.

[0048] In step S204, the control unit 20 estimates the particle size of the particles based on the sounds of the multiple frequency bands from which the environmental sound was cancelled in step S203. Furthermore, the control unit 20 causes the output unit 18 to output the estimation result. Alternatively, the control unit 20 provides the estimation result to an external device. After the estimation of the particle size, the particle size estimation process ends.

[0049] The particle size estimation device 10 of the present embodiment configured as described above estimates the particle size based on the acoustic sensor 14 located near a predetermined facility 11 and collecting the collision sound when a plurality of particles 13 collide with the predetermined facility 11, and the sound collected by the acoustic sensor 14. It is known that the frequency band of the particle collision sound becomes higher and the sound pressure becomes lower as the particle size of the particle becomes smaller. Therefore, with the above-mentioned configuration, the particle size estimation device 10 can accurately estimate the particle size of the particle.

[0050] Moreover, in the particle size estimation device 10 of this embodiment, the particle collision sound is extracted from the sound collected by the acoustic sensor 14. With this configuration, the particle size estimation device 10 extracts the particle collision sound from the sound including the sound that does not contribute to the estimation of the particle size, and therefore the accuracy of the particle size estimation can be improved.

[0051] In addition, in the particle size estimation device 10 of this embodiment, the acoustic sensor 14 separates the collected sound into multiple frequency bands, and estimates the particle size of the particles based on the collision sounds in each of the multiple separated frequency bands. Since the sound pressure in each frequency band differs depending on the particle size, the particle size estimation device 10 can perform estimations corresponding to various particle sizes with the above-mentioned configuration.

[0052] In addition, when the sound pressure of a first band among the separated frequency bands exceeds a first threshold, the particle size estimation device 10 of this embodiment estimates that the particles include particles 13 having a first particle size or larger corresponding to the first band. Specifically, the effect of the above configuration will be explained using actual measurement values ​​of sound pressure in the 0.5 kHz band around a particle size of 31.5 mm. As shown in FIG. 5, in a first graph 21 of the time change in sound pressure in the 0.5 kHz band in the sound when coal with particle sizes of 31.5 to 45 mm is collided with a hopper, the peak value of the sound pressure exceeded 0.05. In addition, in a second graph 22 of the time change in sound pressure in the 0.5 kHz band in the sound when coal with particle sizes of 16 to 31.5 mm is collided with a hopper, the peak value of the sound pressure never exceeded 0.05. In addition, in the third graph 23 showing the time change in sound pressure in the 0.5 kHz band when coal with particle sizes of 16 to 45 mm is collided against a hopper, the peak value of the sound pressure exceeded 0.05. Based on such actual measurement values, when the sound pressure in the 0.5 kHz band exceeds 0.05, it can be estimated that the particle size of the coal to be measured exceeds 31.5 mm. Therefore, the particle size estimation device 10 having the above-mentioned configuration can estimate with high accuracy that the plurality of particles includes particles 13 having a first particle size or larger by setting the first band and the first threshold value according to the actual measurement values ​​for a specific facility 11.

[0053] In addition, when the ratio of the maximum sound pressure of the impact sound in a second band among the separated frequency bands to the maximum sound pressure of the impact sound in a third band larger than the second band exceeds a second threshold value, the particle size estimation device 10 of this embodiment estimates that the particles include only particles 13 having a particle size equal to or smaller than the second particle size corresponding to the second band and the third band. Specifically, the effect of the above configuration will be explained using actual measured values ​​of sound pressure in the 0.5 kHz band and the 14 kHz band around a particle size of 16 mm. As shown in FIG. 6, in the fourth graph 24 of the time change in sound pressure in the 0.5 kHz band when coal with a particle size of 9 to 16 mm is collided with a hopper, the peak value of the sound pressure was about 0.02. In addition, in the fifth graph 25 of the time change in sound pressure in the 14 kHz band when coal with a particle size of 9 to 16 mm is collided with a hopper, the peak value of the sound pressure was close to 0.1. As shown in FIG. 7, in the sixth graph 26 showing the time change of the sound pressure in the 14 kHz band when coal with a particle size of 31.5 to 45 mm is collided with the hopper, the peak value of the sound pressure was about 0.05. Also, in the seventh graph 27 showing the time change of the sound pressure in the 14 kHz band when coal with a particle size of 16 to 31.5 mm is collided with the hopper, the peak value of the sound pressure was about 0.05. As can be seen from the first graph 21 to the seventh graph 27, the ratio of the peak of the sound pressure in the high frequency band to the low frequency band increases as the particle size decreases. Therefore, the particle size estimation device 10 having the above-mentioned configuration can estimate with high accuracy that the plurality of particles includes only particles 13 having a particle size equal to or smaller than the second particle size by setting the second band, the third band, and the second threshold value according to the actual measurement value for the specified equipment 11.

[0054] The above describes an embodiment of the particle size estimation device 10. However, the embodiment of the present disclosure can also be implemented as a method or program for implementing the device, or as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card, etc.).

[0055] The form of implementation of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may be a program module incorporated into an operating system, etc. Furthermore, the program may or may not be configured so that all processing is performed only by the CPU on the control board. The program may be configured so that a part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as necessary.

[0056] The drawings for explaining the embodiments according to the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0057] 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 can make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions, etc. included in each component, etc. can be rearranged so as not to cause logical inconsistencies, and multiple components, etc. can be combined into one or divided.

[0058] All of the features described in this disclosure and / or all steps of any method or process disclosed herein may be combined in any combination except those combinations in which the features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is merely one example of a generic series of the same or equivalent features.

[0059] Furthermore, the embodiments of the present disclosure are not limited to any of the specific configurations of the embodiments described above, but rather extend to any novel feature or combination of features described herein, or any novel method or process step or combination of features described herein.

[0060] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. Configurations distinguished by descriptions such as "first" and "second" in this disclosure may have their numbers exchanged. For example, the first band may exchange identifiers "first" and "second" with the second band. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the exchange of identifiers. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a code. Descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of identifiers with smaller numbers. [Explanation of symbols]

[0061] 10 Particle size estimation device 11 Hopper 12 Conveyor 13 Multiple Particles 14 Acoustic Sensor 15 Information Processing Section 16 Interface 17 Input section 18 Output section 19 Memory section 20 Control section 21 First graph 22 Second Graph 23 Third Graph 24 Fourth Graph 25 5th graph 26 6th graph 27 Seventh Graph

Claims

1. In a pre-sample mode, The sound collected by the acoustic sensor is separated into multiple frequency bands, storing the plurality of frequency bands in a storage unit as frequency bands of environmental sounds; In particle size estimation mode, Multiple particles are collided with a specified facility, A sound of the particles colliding with the predetermined equipment is collected by the acoustic sensor; performing an estimation regarding a particle size of the particle based on the sound collected by the acoustic sensor; The estimation of the particle size of the particle includes extracting a collision sound of the particle from the sound collected by the acoustic sensor; The particle impact sound is extracted by canceling the sound in the frequency band of the environmental sound from among a plurality of frequency bands obtained by separating the sound collected by the acoustic sensor, The estimate of the particle size is: and estimating that the plurality of particles includes only particles having a second particle size or smaller corresponding to the second band and the third band when a ratio of a maximum sound pressure of the impact sound in a second band among the plurality of separated frequency bands to a maximum sound pressure of the impact sound in a third band larger than the second band exceeds a second threshold value. Particle size estimation method.

2. The estimate of the particle size is: Separating the sound collected by the acoustic sensor into a plurality of frequency bands; and performing an estimation of the particle size of the particles based on the impact sound obtained by canceling the environmental sound separated into the plurality of frequency bands in each of the plurality of frequency bands. The method for estimating particle size according to claim 1 .

3. The estimate of the particle size is: and estimating that the plurality of particles includes particles having a first particle size or larger corresponding to a first band among the plurality of separated frequency bands when the sound pressure of the first band exceeds a first threshold. The method for estimating particle size according to claim 2 .

4. The sound collected by the acoustic sensor is in the audible range of 20 kHz or less. The method for estimating particle size according to any one of claims 1 to 3.

5. The plurality of particles includes coal of 5 mm or larger. The method for estimating particle size according to any one of claims 1 to 3.

6. The method includes: an acoustic sensor that is located near a predetermined facility that handles particles to be measured and that collects collision sounds generated when a plurality of particles collide with the predetermined facility; and an information processing unit; The information processing unit includes: In pre-sample mode, Separating the sound collected by the acoustic sensor into a plurality of frequency bands and storing the plurality of frequency bands in a storage unit as frequency bands of environmental sounds; In a particle size estimation mode, the sound corresponding to the environmental sound is separated into sounds of a plurality of frequency bands from the sound collected by the acoustic sensor, and the collision sound of the particles is extracted by canceling the sounds, and an estimation is made regarding the particle size of the particles based on the collision sound. If a ratio of a maximum value of the sound pressure of the collision sound in a second band among the separated plurality of frequency bands to a maximum value of the sound pressure of the collision sound in a third band larger than the second band exceeds a second threshold value, it is estimated that the plurality of particles include only particles having a second particle size or less corresponding to the second band and the third band. Particle size estimation device.

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