JP7167744B2 - Control method and control device - Google Patents

Description

The present invention relates to a control method and control device for a reducing furnace.

As one of the processes for producing reduced iron, powdered iron ore and carbonaceous material such as powdered coal and coke are mixed to form agglomerates such as pellets and briquettes, and such agglomerates are produced. There is a method in which the iron oxide in the iron ore is reduced by charging the product into a reducing furnace such as a rotary hearth furnace and heating it to a high temperature to obtain solid metallic iron. A burner is generally used to heat a reducing furnace such as a rotary hearth furnace. heated. After that, the agglomerates are discharged out of the furnace and sent to the melting process.

If the agglomerate is crushed and has a particle size of several millimeters or less, it will be sucked up by a dust collector, leading to a deterioration in yield. Patent Literature 1 discloses a technique capable of simultaneously determining the particle size and temperature of an agglomerate from a photographed image of the agglomerate discharged from a reducing furnace.

JP 2017-72433 A

Scattering loss refers to the percentage of agglomerates transported from the reduction furnace to the next melting process, which scatters and is collected by a dust collector, and does not stay in the melting furnace and contribute to the steel output. . If the scattering loss becomes large, the yield deteriorates and the operation of the reducing furnace becomes unstable.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and apparatus for controlling a reducing furnace so as to suppress scattering loss of agglomerates.

A control method for a reducing furnace according to the present invention includes an imaging step of sequentially imaging agglomerates discharged from a reducing furnace to generate a photographed image; a particle size calculation step of calculating the particle size of the agglomerate; a scattering loss calculation step of calculating the scattering loss of the agglomerate in the next process from the particle size calculated in the particle size calculation step; and discharging from the reducing furnace. A temperature at which the scattering loss is equal to or less than a certain value is obtained from the correlation between the ratio of the agglomerates having a particle size of a predetermined value or less among the agglomerates obtained and the average furnace temperature of the reducing furnace, and the reducing furnace and a control step of setting to the temperature.

A control device for a reducing furnace according to the present invention comprises an imaging device for sequentially imaging agglomerates discharged from a reducing furnace to generate a photographed image; and an arithmetic processing unit for controlling. The arithmetic processing unit includes: a particle size calculation unit for performing image processing on the photographed image generated by the imaging device to calculate the particle size of the agglomerate; a scattering loss calculation unit that calculates the scattering loss of the agglomerates in the reducing furnace; a temperature control unit that obtains a temperature at which the scattering loss is equal to or less than a certain value from the correlation with the average furnace temperature, and sets the reducing furnace to the temperature.

According to the present invention, the temperature of the reducing furnace is set according to the ratio of the agglomerates having a particle size of a predetermined value or less so as to reduce the scattering loss of the agglomerates discharged from the reducing furnace. Furnace operation can be stabilized.

It is a figure which shows typically the whole structure of the control apparatus which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the installation state of the imaging device of this embodiment. It is a figure which shows an example of the picked-up image produced|generated with the imaging device. 3 is a functional block diagram of an image processing unit included in the arithmetic processing device of the embodiment; FIG. 4 is a flow chart showing a method of controlling a rotary hearth furnace executed by the control device of the present embodiment; 10 is a graph showing the correlation between the ratio of powder particles having a predetermined particle size or less and the amount of variation from the standard of scattering loss. 4 is a table showing the correlation between the average furnace temperature of a rotary hearth furnace and the proportion of powder having a predetermined particle size or less.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or similar configurations are denoted by the same reference numerals, and overlapping descriptions are omitted.

<Overall configuration of control device>
First, the configuration of the control device 10 according to the embodiment of the present invention will be described. FIG. 1 is a diagram schematically showing the overall configuration of a control device 10 according to this embodiment.

The control device 10 is a device that determines the scattering loss from the particle size of the agglomerates discharged from the reducing furnace and controls the temperature of the reducing furnace based on the determined scattering loss. The control device 10 mainly includes an imaging device 100 and an arithmetic processing device 200, as shown in FIG.

Here, the reducing furnace is an agglomerate such as pellets and briquettes formed by mixing powdered iron ore (iron oxide) and carbonaceous material (that is, reducing agent) such as powdered coal and coke. Iron oxide in the iron ore is reduced by heating the agglomerate to a high temperature to produce solid metallic iron (that is, reduced iron). In this embodiment, a rotary hearth furnace (RHF) is taken up as an example of a reducing furnace.

The imaging device 100 is installed in the vicinity of the out-of-furnace discharge port 301 of the rotary hearth furnace 300, and is a device that takes an image of the agglomerates falling inside the out-of-furnace discharge port 301 to generate a photographed image.

The imaging device 100 includes various optical elements such as lenses, and an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Here, the imaging device 100 may be capable of generating still images or may be capable of generating moving images. Further, the imaging device 100 may be capable of capturing a monochrome image, or may be capable of capturing a color image. When using an imaging device capable of capturing a color image, a one-channel image may be generated. That is, as means for generating a captured image, only one of the R, G, and B components of the RGB components may be used, or the RGB color space may be converted into the YCbCr color space, and only the Y component may be used. You can use it.

The imaging device 100 is controlled by an arithmetic processing device 200, and imaging is performed by outputting a trigger signal for imaging from the arithmetic processing device 200 at each predetermined frame rate. The imaging device 100 captures the thermal radiation of the agglomerates falling inside the outlet 301 of the rotary hearth furnace 300 in response to a trigger signal output from the processing device 200 to generate a captured image, The generated photographed image is output to the arithmetic processing unit 200 .

FIG. 2 is a schematic diagram for explaining the installation state of the imaging device 100, and FIG. 3 is an example of a captured image generated by the imaging device 100. As shown in FIG. The imaging device 100 is installed near an observation window 302 for observing the state of the out-of-furnace discharge port 301, as shown in FIG. Inside the out-of-furnace discharge port 301, the agglomerate 1 discharged from the rotary hearth furnace 300 drops at any time. The imaging device 100 is installed, for example, at a position separated by about 2 m from the observation window 302, and sequentially images the thermal radiation of the agglomerates 1 falling inside the outlet 301 through the observation window 302, A photographed image (thermal radiation image) as shown in FIG. 3 is generated. Here, the temperature of the agglomerate 1 in the outlet 301 outside the furnace is about 800.degree. C. to 1000.degree.

As shown in FIG. 3, the thermal radiation image generated by the imaging device 100 is inside the field of view corresponding to the observation window 302 (in FIG. 3, a substantially circular field of view with a diameter of about 160 mm) of the furnace discharge port 301. The agglomerate 1 falling inside is reflected. In such a thermal radiation image, the agglomerate 1 having a higher temperature appears whiter in the thermal radiation image, and the agglomerate 1 having a lower temperature appears blacker in the thermal radiation image.

As shown in FIG. 1, the arithmetic processing unit 200 includes an imaging control unit 201, an image processing unit 203, a display control unit 205, a storage unit 207, a scattering loss calculation unit 209, and a temperature control unit 210. Prepare. The arithmetic processing unit 200 includes, for example, a CPU (Central Processing Unit). The CPU executes an imaging control unit 201, an image processing unit 203, a display control unit 205, and a scattering loss calculation according to various programs stored in a storage unit 207. Each function in the unit 209 and the temperature control unit 210 is controlled.

The imaging control unit 201 controls imaging processing by the imaging device 100 . More specifically, the imaging control unit 201 causes the imaging device 100 to perform imaging at each predetermined frame rate when imaging the inside of the furnace outlet 301 of the rotary hearth furnace 300. to send a trigger signal.

The image processing unit 203 acquires a photographed image of the agglomerate 1 from the imaging device 100, performs image processing on the acquired photographed image, detects the agglomerate 1, and determines the particle size of the detected agglomerate 1. (particle size distribution) is calculated. Detailed functions of the image processing unit 203 will be described later (see FIG. 4).

The display control unit 205 displays the captured image generated by the imaging device 100 , the processing result of the image processing unit 203 , the calculation result of the scattering loss calculation unit 209 , and information about temperature control by the temperature control unit 210 on the display unit 206 . to display.

The display unit 206 includes a display such as a liquid crystal display (LCD), a plasma display, or an organic electroluminescence (EL) display. A processing result in the processing device 200 is displayed.

The storage unit 207 includes ROM (Read Only Memory) and RAM (Random Access Memory). The ROM stores various programs such as a control processing program (see FIG. 5) executed by the CPU, and data necessary for executing these programs. Various programs and data stored in the ROM are loaded into the RAM and executed.

Note that the storage unit 207 may include a magnetic memory such as a hard disk drive (HDD) or an optical memory such as an optical disk. Alternatively, various programs and data may be stored in a computer-readable recording medium that is detachable from the processing unit 200 . Alternatively, various programs executed by the arithmetic processing unit 200 may be received via a communication network.

The scattering loss calculation unit 209 calculates the scattering loss of the agglomerate 1 in the next step (dissolving step) from the particle size (particle size distribution) of the agglomerate 1 calculated by the image processing unit 203 . The calculation of scattering loss will be described later (see FIGS. 5 and 6).

The temperature control unit 210 controls the correlation between the ratio (%) of powder having a predetermined particle size or less and the average furnace temperature (°C) of the rotary hearth furnace 300 (Fig. 7 ), the temperature corresponding to the ratio (%) of powder having a predetermined particle size or less, which is correlated with the scattering loss, is obtained, and the inside of the rotary hearth furnace 300 is set to that temperature. The ratio (%) of particles having a particle size equal to or less than a predetermined particle size is the ratio of agglomerates 1 having a particle size equal to or less than a predetermined value to all the agglomerates 1 detected by the image processing unit 203 . The temperature control by the temperature control section 210 will be described later (see FIGS. 5 and 7).

Note that the arithmetic processing unit 200 may be configured with general-purpose hardware, or may be configured with hardware specialized for each function of the processing unit 200 . For example, the functions of the image processing unit 203 may be configured by hardware such as an application specific integrated circuit (ASIC).

Next, functions of the image processing unit 203 will be described with reference to FIG. FIG. 4 is a functional block diagram of the image processing unit 203. As shown in FIG.

The image processing unit 203 has a function of calculating the particle size of the agglomerate 1 from the photographed image of the agglomerate 1 generated by the imaging device 100. As shown in FIG. It has an image generation unit 213 , a linear function calculation unit 215 , a threshold value determination unit 217 , a binarized image generation unit 219 , a composite image generation unit 221 , a labeling unit 223 , and a granularity calculation unit 225 . In this embodiment, the method disclosed in Patent Document 1 is adopted as the method of calculating the particle size of the agglomerated material 1 executed by the image processing unit 203 .

The preprocessing unit 211 performs various preprocessing as necessary on the photographed image (thermal radiation image) of the agglomerated material 1 falling inside the out-of-furnace discharge port 301 output from the imaging device 100. Apply. As such pre-processing, for example, image reduction processing for reducing a captured image to a predetermined image size can be cited. The degree of reduction is not particularly limited as long as the powdery agglomerate 1 exists as at least one pixel in the photographed image after reduction. The preprocessing unit 211 can arbitrarily set the reduction ratio of the captured image, and for example, can execute image reduction processing that reduces the captured image to ⅓ both vertically and horizontally. By executing such image reduction processing, it is possible to further shorten the calculation time of the following image processing.

The filtered image generation unit 213 applies a plurality of normalized Laplacian-Gaussian filters (hereinafter referred to as “normal (referred to as a "simplified LoG filter") to generate a plurality of filtered images.

The functional form of the normalized LoG filter is given by equation (1) below.

The filtered image generation unit 213 sets the coordinates of the center to (0, 0), and the weight of the pixel that is (i, j) pixels away from the center is given by formula (1) as follows: (x, y)=(i, j) is created, and the thermal radiation image is multiplied by the filter to perform filtering.

Specifically, such a filtering process assumes that the thermal radiation image expressed in luminance is f(x, y), and f(x, y) at coordinates (x, y) is multiplied by φ(0, 0) to It is defined as the sum over parameters i,j with respect to f(x+i,y+j) at (x+i,y+i) multiplied by φ(i,j). That is, by calculating g(x, y) represented by the following equation (2), it is possible to obtain a thermal radiation image after applying the normalized LoG filter.

A plurality of normalized LoG filters with different values of standard deviation σ are a first normalized LoG filter group used for detecting agglomerates 1 having a first diameter or less (that is, agglomerates 1 ) and a second normalized LoG filter group used to detect agglomerates 1 of a second diameter or larger (i.e., medium to large grain size agglomerates 1 Normalized LoG filter group for detection). Specific numerical values of the first diameter and the second diameter can be appropriately set by analyzing the particle size distribution of the agglomerate 1 produced in the rotary hearth furnace 300 in advance by a known measurement method. good.

When the first diameter is 3 mm (about 1/5 or less of the average particle size of the agglomerate 1), the first normalized LoG filter group includes, for example, σ=1/3, 2/3, 1, Four normalized LoG filters with a value of 2 can be used. When the second diameter is 8 mm, as the second normalized LoG filter group, for example, four types of normalized LoG filters set with values of σ = 3, 4, ..., 6 can be used. can.

Hereinafter, the filtered image group generated by the action of the first normalized LoG filter group will be referred to as the first filtered image group, and the filtered image group generated by the action of the second normalized LoG filter group will be referred to as the second filter processed image group. It will be called a group of filtered images.

The linear function calculation unit 215 calculates a linear function used for determining a threshold value when binarizing a filtered image in a threshold value determination unit 217, which will be described later. This linear function is a linear function representing the correspondence relationship between the average luminance value of the first filtered image group and the average luminance value of the second filtered image group. More specifically, when the average luminance value of the first filtered image group is X, and the average luminance value of the second filtered image group is Y, the combination of (X, Y) is expressed in the XY plane , and a set of lower limit values of Y at each X position is obtained by linear approximation by a known method such as the least squares method (see FIG. 7 of Patent Document 1). Data of the linear function (Y=AX+B) calculated in this way is stored in the storage unit 207 .

It should be noted that the process of calculating the linear function may be performed at least once as long as the imaging environment of the agglomerated material 1 by the imaging device 100 does not change, and does not need to be performed each time a photographed image is generated by the imaging device 100. do not have.

The threshold determination unit 217 determines a threshold (first threshold) for binarizing the first filtered image group, and determines the second filtered image based on the linear function calculated by the linear function calculation unit 215. A threshold (second threshold) for binarizing the group is determined.

Specifically, the threshold determination unit 217 sets the threshold (first threshold) for detecting agglomerates 1 having a diameter equal to or less than the first diameter to a predetermined fixed value with respect to the average luminance value of the first filtered image group. The value is multiplied by More specifically, the threshold determining unit 217 also detects the agglomeration 1 having a brightness of _Xr or less, considering the brightness variation of the agglomeration 1, with respect to the average brightness value _Xr of the first filtered image group. , the first threshold is obtained by multiplying by one value (for example, 0.5) included in the range of 0.4 to 0.6.

The reason why the first threshold value is obtained by multiplying the average brightness value _Xr by a certain fixed value is that the agglomerates 1 with small particle diameters included in the first filtered image group have less temperature unevenness, This is because binarization is also considered to be easy.

Further, the threshold determination unit 217 sets the threshold (second threshold) for detecting the agglomerates 1 having a second diameter or more to the linear function (Y=AX+B) calculated by the linear function calculation unit 215 as the average brightness. Let the value Y _r be obtained by substituting the value X _r . Thus, the second threshold is not a fixed value, but a value that varies according to the average luminance value of the first filtered image group. This makes it possible to set the threshold value for detecting the agglomerate 1 having medium to large particle diameters to a value that does not cause non-detection or over-detection.

The binarized image generation unit 219 generates a binarized image by binarizing each image included in the first filtered image group using the first threshold, and generates a binarized image using the second threshold. Each image included in the filtered image group is binarized to generate a binarized image.

The composite image generator 221 synthesizes a plurality of binarized images generated by the binarized image generator 219 to generate a composite binarized image.

In addition, in the binarized image obtained from the first filtered image group, it is conceivable that the outer shape of the agglomerates 1 with medium to large particle diameters remains. In this case, the synthesized image generation unit 221 first separately synthesizes the binarized image obtained from the first filtered image and the binarized image obtained from the second filtered image, and An image obtained by subtracting the synthesized image obtained from the second filtered image from the synthesized image obtained from the processed image (difference image) is used as the synthesized image of the first filtered image to be used as the final synthesized image. can be By using such a difference image, it becomes possible to detect the agglomerated material 1 having a small particle size more accurately.

The labeling unit 223 refers to the composite binarized image generated by the composite image generation unit 221, and performs labeling processing on the portion where the luminance value is 1, thereby identifying the agglomerate 1 contained in the binarized image. identify and detect Note that the labeling process executed by the labeling unit 223 is not particularly limited, and a known labeling process can be applied.

The particle size calculator 225 calculates the particle size of each of the agglomerates 1 detected by the labeling unit 223 . The particle size of the agglomerate 1 includes, for example, the area S of the agglomerate 1, the peripheral length (the length along the outer shape of the agglomerate 1) L, the equivalent diameter (0.5×(S/π)), Examples include the length of the major axis, the length of the minor axis, and the like. The length of the major axis is the length of the major axis in the equivalent ellipse of the agglomerate 1 (an ellipse having the same area as the agglomerate 1 and having the same first and second moments), and the length of the minor axis is This is the length of the minor axis of the equivalent ellipse.

<Flow of control method>
Next, the flow of the control method executed by the control device 10 will be described with reference to FIGS. 5 to 7. FIG. FIG. 5 is a flow chart of a control method executed by the control device 10. As shown in FIG.

First, the imaging device 100 sequentially images the agglomerates 1 falling inside the outlet 301 outside the furnace of the rotary hearth furnace 300 under the control of the imaging control unit 201 to generate a photographed image (step S101). , and outputs the generated photographed image to the arithmetic processing unit 200 .

Next, the preprocessing unit 211 acquires the captured image generated by the imaging device 100, and performs preprocessing such as reduction processing as necessary on the acquired captured image (step S103).

Next, the filtered image generation unit 213 applies a plurality of normalized LoG filters having different values of standard deviation σ to the captured image obtained in step S101 or the captured image after preprocessing to perform a plurality of filtering processes. Images (first filtered image group and second filtered image group) are generated (step S105).

The linear function calculation unit 215 uses the first filtered image group and the second filtered image group generated by the filtered image generation unit 213 to calculate the linear function used when the threshold determination unit 217 calculates the second threshold. calculated by The threshold determining unit 217 calculates the average luminance value of the first filtered image group, and multiplies the average luminance value by a predetermined fixed value to obtain the first threshold value for binarizing the first filtered image group. A threshold value is determined, and a second threshold value for binarizing the second filtered image group is determined using the linear function obtained by the linear function calculation unit 215 and the average luminance value of the first filtered image group. (Step S107).

Next, the binarized image generation unit 219 generates a binarized image by binarizing each image included in the first filtered image group using the first threshold, and using the second threshold, Each image included in the second filtered image group is binarized to generate a binarized image (step S109).

Next, the composite image generator 221 composites the binarized images generated by the binarized image generator 219 to generate a composite binarized image (step S111).

Next, the labeling unit 223 detects the agglomerated material 1 by labeling the part having the brightness value=1 in the synthesized binarized image (step S113).

Next, the particle size calculator 225 calculates the particle size (particle size distribution) of the agglomerate 1 detected by the labeling unit 223 (step S115).

Next, the scattering loss calculator 209 calculates the scattering loss of the agglomerate 1 in the next step (dissolving step) from the particle size calculated in step S115 (step S117). Specifically, the storage unit 207 stores calibration curve data indicating the relationship between the particle size of the agglomerates and the scattering loss, and the scattering loss calculation unit 209 calculates the particle size calculated in step S115 as the calibration curve. By applying to , the scattering loss is obtained.

FIG. 6 shows the result of plotting the correlation between the ratio (%) of powders having a predetermined particle size or smaller and the Δ scattering loss (%). In FIG. 6, the ratio (%) of powder having a predetermined particle size or less is the amount (number) of all the agglomerates 1 detected in the labeling section 223. It is the ratio of the amount (number) of the agglomerate 1. The Δ scattering loss (%) is the amount of variation from the scattering loss reference (%) (the amount of variation up to +1.5 (%) in FIG. 6). From FIG. 6, it can be seen that the Δ scattering loss increases as the proportion of powder having a particle size equal to or smaller than a predetermined particle size increases. As a result, it can be seen that there is a clear correlation between the powder ratio of particles having a predetermined particle size or smaller and the Δ scattering loss. Therefore, it can be seen that in order to reduce the Δ scattering loss and improve the yield, the operation should be controlled so as to reduce the proportion of powder having a predetermined particle size or less. Note that once the calibration curve data shown in FIG. 6 is created, it is not necessary to determine the scattering loss each time the operation is controlled, so S117 can be omitted.

Next, the ratio (%) of powder having a predetermined particle size or less corresponding to the target scattering loss is obtained so that the scattering loss is kept below a certain level, and the temperature control unit 210 determines the ratio (%) of powder having a predetermined particle size or less. From the correlation with the average furnace temperature (° C.) of the rotary hearth furnace 300, the temperature corresponding to the powder ratio (%) of the obtained predetermined particle size or less is obtained, and the inside of the rotary hearth furnace 300 is set to that temperature (step S119).

FIG. 7 shows the result of investigating the correlation between the ratio (%) of powder having a predetermined particle size or smaller (the first diameter or smaller) and the average furnace temperature (° C.) of the rotary hearth furnace 300 . Here, the average furnace temperature (° C.) is the average value of the atmospheric temperature of the rotary hearth furnace 300 measured by a thermometer such as a thermocouple thermometer installed in the rotary hearth furnace 300 . Data shown in FIG. 7 are stored in the storage unit 207 . From FIG. 7, for example, if the average furnace temperature of the rotary hearth furnace 300 is set to 1280° C. or higher, the proportion of powder having a predetermined particle size or less is 4% or less, and from FIG. 6, Δ scattering loss is 0.5% or less. can be suppressed. Therefore, for example, the temperature control unit 210 sets the temperature of the rotary hearth furnace 300 to 1280°C. Raising the temperature of the rotary hearth furnace 300 directly leads to an increase in production costs, so it is not preferable to raise the temperature excessively. By finding the optimum temperature conditions, it becomes possible to control to the optimum operating conditions.

As described above, according to the present embodiment, the arithmetic processing device 200 obtains the particle size of the agglomerate 1 from the photographed image obtained by photographing the agglomerate 1 with the imaging device 100, and the scattering loss from the obtained particle size. is calculated, and the furnace temperature is controlled so as to suppress scattering loss. As a result, it is possible to realize stable operation with suppressed scattering loss without excessively increasing the temperature of the rotary hearth furnace 300 .

Note that the contents of description in this embodiment can be changed as appropriate without departing from the gist of the present invention.
For example, in the above-described embodiment, the normalized LoG filter is applied to the captured image to generate a plurality of filtered images, but the type of filter applied to the captured image is not particularly limited.
Further, in the above-described embodiment, the first diameter necessary for the calculation of the scattering loss is about 1/5 of the average particle diameter of the agglomerate 1, but the size of the first diameter is not particularly limited. For example, the first diameter may be about 1/10 of the average particle size of the agglomerate 1 .

1 agglomerate 10 control device 100 imaging device 200 arithmetic processing device 201 imaging control unit 203 image processing unit 205 display control unit 206 display unit 207 storage unit 209 scattering loss calculation unit 210 temperature control unit 211 preprocessing unit 213 filtered image generation Part 215 Linear function calculation part 217 Threshold determination part 219 Binary image generation part 221 Synthetic image generation part 223 Labeling part 225 Particle size calculation part 300 Rotary hearth furnace 301 Out-of-furnace discharge port 302 Observation window

Claims (5)

an imaging step of sequentially imaging the agglomerates discharged from the reduction furnace to generate a photographed image;
a particle size calculation step of performing image processing on the captured image generated in the imaging step to calculate the particle size of the agglomerate;
a scattering loss calculation step of calculating the scattering loss of the agglomerate in the next step from the particle size calculated in the particle size calculating step;
The temperature at which the scattering loss is below a certain level is determined from the correlation between the ratio of the agglomerates having a particle size of a predetermined value or less among the agglomerates discharged from the reducing furnace and the average furnace temperature of the reducing furnace. a control step of obtaining and setting the reducing furnace to the temperature;
A method of controlling the reducing furnace, comprising: 2. The particle size calculation step according to claim 1, wherein at least one of the area, perimeter, equivalent diameter, major axis length, and minor axis length of the agglomerate is calculated as the particle size. control method. 3. The control method according to claim 1 or 2, wherein the ratio of said agglomerates having a particle size equal to or less than a predetermined value is a ratio of said agglomerates having an average particle size of 1/5 or less of the average particle size of said agglomerates. The control method is
a filtered image generating step of performing filter processing on the captured image to generate a filtered image;
a binarized image generating step of binarizing the filtered image to generate a binarized image;
a detection step of detecting the agglomerates from the binarized image;
with
The particle size calculation step includes:
The control method according to any one of claims 1 to 3, wherein the particle size of the agglomerates detected in the detection step is calculated. an imaging device that sequentially images the agglomerate discharged from the reduction furnace to generate a captured image;
an arithmetic processing device that controls the reducing furnace based on the captured image generated by the imaging device;
The arithmetic processing unit is
a particle size calculation unit that performs image processing on the captured image generated by the imaging device to calculate the particle size of the agglomerate;
a scattering loss calculation unit that calculates the scattering loss of the agglomerate in the next step from the particle size calculated by the particle size calculation unit;
Based on the correlation between the ratio of agglomerates having a particle size of a predetermined value or less among the agglomerates discharged from the reducing furnace and the average furnace temperature of the reducing furnace, the temperature at which the scattering loss is below a certain level is determined. a temperature control unit that obtains and sets the reducing furnace to the temperature;
A controller for the reducing furnace, comprising:

Images